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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Mar. 08, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	ACMR
Entity Registrant Name	ACM RESEARCH, INC.
Entity Central Index Key	0001680062
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		14,176,690
Entity Public Float			$ 0

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 27,124	$ 17,681
Accounts receivable, less allowance for doubtful accounts of $0 and $0 as of December 31, 2018 and 2017, respectively (note 3)	24,608	26,762
Other receivables	3,547	2,491
Inventory (note 4)	38,764	15,388
Prepaid expenses	1,985	546
Other current assets	0	46
Total current assets	96,028	62,914
Property, plant and equipment, net (note 5)	3,708	2,340
Intangible assets, net	274	106
Deferred tax assets (note 15)	1,637	1,294
Investment in affiliates, equity method (note 10)	1,360	1,237
Other long-term assets	40	0
Total assets	103,047	67,891
Current liabilities:
Short-term borrowings (note 6)	9,447	5,095
Warrant liability (note 8)	0	3,079
Accounts payable	16,673	7,419
Advances from customers	8,417	143
Income tax payable	1,193	44
Other payables and accrued expenses (note 7))	10,410	6,037
Total current liabilities	46,140	21,817
Other long-term liabilities (note 9)	4,583	6,217
Total liabilities	50,723	28,034
Commitments and contingencies (Note 16)
Stockholders' equity:
Additional paid in capital	56,567	49,695
Accumulated deficit	(3,387)	(9,961)
Accumulated other comprehensive income (loss)	(857)	122
Total stockholders' equity	52,324	39,857
Total liabilities and stockholders' equity	103,047	67,891
Common Class A [Member]
Stockholders' equity:
Common stock	1	1
Common Class B [Member]
Stockholders' equity:
Common stock	$ 0	$ 0

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts receivable, allowance for doubtful accounts	$ 0	$ 0
Common Class A [Member]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	14,110,315	12,935,546
Common stock, shares outstanding	14,110,315	12,935,546
Common Class B [Member]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	7,303,533	7,303,533
Common stock, shares issued	1,898,423	2,409,738
Common stock, shares outstanding	1,898,423	2,409,738

Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 74,643	$ 36,506
Cost of revenue	40,194	19,281
Gross profit	34,449	17,225
Operating expenses, net:
Sales and marketing	9,611	5,500
Research and development	10,380	5,138
General and administrative	7,987	5,887
Total operating expenses, net	27,978	16,525
Income from operations	6,471	700
Interest income	29	9
Interest expense	(498)	(277)
Other? income (expense),? net	1,255	(794)
Equity in net income of affiliates	123	37
Income (loss) before income taxes	7,380	(325)
Income tax expense (note 17)	(806)	(547)
Net income (loss)	6,574	(872)
Less: Net income (loss) attributable to non-controlling interests	0	(554)
Net income (loss) attributable to ACM Research, Inc.	6,574	(318)
Comprehensive income (loss):
Net income (loss)	6,574	(872)
Foreign currency translation adjustment	(979)	472
Comprehensive income (loss)	5,595	(400)
Less: Comprehensive income (loss) attributable to non-controlling interests	0	(369)
Total comprehensive income (loss) attributable to ACM Research, Inc.	$ 5,595	$ (31)
Net income (loss) per common shares (note 2)
Basic	$ 0.42	$ (0.05)
Diluted	$ 0.37	$ (0.05)
Weighted average common stocks outstanding used in computing per share amounts (note 2)
Basic	15,788,460	6,865,390
Diluted	17,912,105	6,865,390

Consolidated Statement of Changes in Redeemable Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Preferred Stock Series A	Preferred Stock Series B	Preferred Stock Series C	Preferred Stock Series D	Preferred Stock Series E	Preferred Stock Series F	Preferred Stock Total	Common Stock	Common Stock Class A	Common Stock Class B	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Noncontrolling Interest	Total
Beginning balance, shares at Dec. 31, 2016	385,000	1,572,000	1,360,962	1,326,642	0	3,663,254		0	2,228,740	2,409,738
Beginning balance, amount at Dec. 31, 2016	$ 288	$ 1,572	$ 2,041	$ 4,975	$ 0	$ 9,158	$ 18,034	$ 0	$ 1	$ 1	$ 7,620	$ (9,643)	$ (413)	$ 4,919	$ 2,485
Net income (loss)												(318)		(554)	(872)
Foreign currency translation adjustment													535	185	720
Exercise of stock option, shares									472,887
Exercise of stock option, amount											396				396
Stock-based compensation											1,622				1,622
Purchase of non-controlling interest											(16,258)			(4,550)	20,808
Issuance of Series E Preferred Stock, shares					4,998,508
Issuance of Series E Preferred Stock, amount					$ 5,800		5,800
Issuance of Common Stock to Ninebell, shares									133,334
Issuance of Common Stock to Ninebell, amount											1,000				1,000
Issuance of Common Stock to Shanghai and Pudong VC, shares									1,906,674
Issuance of Common Stock to Shanghai and Pudong VC, amount											14,299				14,299
Convertible preferred shares converted to common shares in connection with initial public offering, shares	(385,000)	(1,572,000)	(1,360,962)	(1,326,642)	(4,998,508)	(3,663,254)			4,627,577
Convertible preferred shares converted to common shares in connection with initial public offering, amount	$ (288)	$ (1,572)	$ (2,041)	$ (4,975)	$ (5,800)	$ (9,158)	$ (23,834)				23,834				23,834
Issuance of Class A common stock in connection with inital public offering and concurrent private placement, net of issuance costs of $2,791 and underwriter's warrant of $137, shares									3,566,334
Issuance of Class A common stock in connection with inital public offering and concurrent private placement, net of issuance costs of $2,791 and underwriter's warrant of $137, amount											17,044				17,044
Issuance of underwriter's warrant, amount											137				137
Reclassification of reverse split par value										$ (1)	1
Ending balance, shares at Dec. 31, 2017	0	0	0	0	0	0	0	0	12,935,546	2,409,738
Ending balance, amount at Dec. 31, 2017	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 1	$ 0	49,695	(9,961)	122	0	39,857
Net income (loss)												6,574			6,574
Foreign currency translation adjustment													(979)		(979)
Exercise of stock option, shares									265,952
Exercise of stock option, amount											528				528
Stock-based compensation											3,363				3,363
Purchase of non-controlling interest															0
Convertible preferred shares converted to common shares in connection with initial public offering, amount															0
Conversion of class B common shares to Class A common shares									511,315	(511,315)
Exercise of common stock warrant issued to SMC									397,502
Exercise of common stock warrant issued to SMC, amount											2,981				2,981
Ending balance, shares at Dec. 31, 2018	0	0	0	0	0	0	0	0	14,110,315	1,898,423
Ending balance, amount at Dec. 31, 2018	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 1	$ 0	$ 56,567	$ (3,387)	$ (857)	$ 0	$ 52,324

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ 6,574	$ (872)
Adjustments to reconcile net loss from operations to net cash provided by operating activities:
Depreciation and amortization	417	271
Equity income in net income of affiliates	(123)	(37)
Deferred income taxes	(405)	659
Stock-based compensation	3,363	1,622
Loss on disposals of fixed assets, intangible assets and other long-term assets	0	1
Net changes in operating assets and liabilities:
Accounts receivable	883	(9,757)
Other receivables	(1,171)	332
Inventory	(24,083)	(3,073)
Prepaid expenses	(1,494)	256
Other current assets	44	8
Accounts payable	9,825	1,905
Advances from customers	8,316	(127)
Income tax payable	1,149	0
Other payables and accrued expenses	4,954	1,789
Other long-term liabilities	(1,340)	(1,078)
Net cash provided by (used in) operating activities	6,909	(8,101)
Cash flows from investing activities:
Purchase of property and equipment	(1,830)	(651)
Purchase of intangible assets	(241)	(115)
Loan to related party	0	(946)
Purchase of non-controlling interest	0	(20,808)
Investments in unconsolidated equity method affiliates	0	(1,200)
Net cash used in investing activities	(2,071)	(23,720)
Cash flows from financing activities:
Proceeds from short-term borrowings	17,726	11,154
Repayments of short-term borrowings	(13,131)	(11,110)
Proceeds from stock option exercise to common stock	528	396
Proceed from issuance of Series E convertible preferred stock	0	5,800
Proceeds from issuance of common stock in connection with initial public offering and concurrent private placement	0	18,717
Payment of inital public offering expenses	0	(1,537)
Investment in affiliates	0	1,000
Proceeds from issuance of common stock for non-controlling interest purchase	0	14,300
Net cash provided by financing activities	5,123	38,720
Effect of exchange rate changes on cash and cash equivalents	(518)	663
Net increase in cash and cash equivalents	9,443	7,562
Cash and cash equivalents at beginning of period	17,681	10,119
Cash and cash equivalents at end of period	27,124	17,681
Supplemental disclosure of cash flow information:
Interest paid	498	277
Non-cash financing activities:
Preferred stock conversion to common stock in connection with initial public offering	0	23,834
Warrant conversion to common stock	$ 3,079	$ 0

Description of Business

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Description of Business

ACM Research, Inc. (“ACM”) and its subsidiaries (collectively with ACM, the “Company”) develop, manufacture and sell single-wafer wet cleaning equipment used to improve the manufacturing process and yield for advanced integrated chips. The Company markets and sells its single-wafer wet-cleaning equipment, under the brand name “Ultra C,” based on the Company’s proprietary Space Alternated Phase Shift (“SAPS”) and Timely Energized Bubble Oscillation (“TEBO”) technologies. These tools are designed to remove random defects from a wafer surface efficiently, without damaging the wafer or its features, even at increasingly advanced process nodes.

ACM was incorporated in California in 1998, and it initially focused on developing tools for manufacturing process steps involving the integration of ultra low-K materials and copper. The Company’s early efforts focused on stress-free copper-polishing technology, and it sold tools based on that technology in the early 2000s.

In 2006 the Company established its operational center in Shanghai in the People’s Republic of China (the “PRC”), where it operates through ACM’s subsidiary ACM Research (Shanghai), Inc. (“ACM Shanghai”). ACM Shanghai was formed to help establish and build relationships with integrated circuit manufacturers in the PRC, and the Company initially financed its Shanghai operations in part through sales of non-controlling equity interests in ACM Shanghai.

In 2007 the Company began to focus its development efforts on single-wafer wet-cleaning solutions for the front-end chip fabrication process. The Company introduced its SAPS megasonic technology, which can be applied in wet wafer cleaning at numerous steps during the chip fabrication process, in 2009. It introduced its TEBO technology, which can be applied at numerous steps during the fabrication of small node two-dimensional conventional and three-dimensional patterned wafers, in March 2016. The Company has designed its equipment models for SAPS and TEBO solutions using a modular configuration that enables it to create a wet-cleaning tool meeting the specific requirements of a customer, while using pre-existing designs for chamber, electrical, chemical delivery and other modules. In August 2018, the Company introduced its Ultra-C Tahoe wafer cleaning tool, which can deliver high cleaning performance with significantly less sulfuric acid than typically consumed by conventional high-temperature single-wafer cleaning tools. The Company also offers a range of custom-made equipment, including cleaners, coaters and developers, to back-end wafer assembly and packaging factories, principally in the PRC.

In 2011 ACM Shanghai formed a wholly owned subsidiary in the PRC, ACM Research (Wuxi), Inc. (“ACM Wuxi”), to manage sales and service operations.

In November 2016 ACM redomesticated from California to Delaware pursuant to a merger in which ACM Research, Inc., a California corporation, was merged into a newly formed, wholly owned Delaware subsidiary, also named ACM Research, Inc.

In June 2017 ACM formed a wholly owned subsidiary in Hong Kong, CleanChip Technologies Limited (“CleanChip”), to act on the Company’s behalf in Asian markets outside the PRC by, for example, serving as a trading partner between ACM Shanghai and its customers, procuring raw materials and components, performing sales and marketing activities, and making strategic investments.

In August 2017 ACM purchased 18.77% of ACM Shanghai’s equity interests held by Shanghai Science and Technology Venture Capital Co., Ltd. On November 8, 2017, ACM purchased the remaining 18.36% of ACM Shanghai’s equity interest held by third parties, Shanghai Pudong High-Tech Investment Co., Ltd. (“PDHTI”) and Shanghai Zhangjiang Science & Technology Venture Capital Co., Ltd. (“ZSTVC”). At December 31, 2017, ACM owned all of the outstanding equity interests of ACM Shanghai, and indirectly through ACM Shanghai, owned all of the outstanding equity interests of ACM Wuxi..

On September 13, 2017, ACM effectuated a 1-for-3 reverse stock split of Class A and Class B common stock. Unless otherwise indicated, all share numbers, per share amount, share prices, exercise prices and conversion rates set forth in these notes and the accompanying condensed consolidated financial statements have been adjusted retrospectively to reflect the reverse stock split.

On November 2, 2017, the Registration Statement on Form S-1 (File No. 333- 220451) for ACM’s initial public offering of Class A common stock (the “IPO”) was declared effective by the U.S. Securities and Exchange Commission. Shares of Class A common stock began trading on the Nasdaq Global Market on November 3, 2017, and the closing for the IPO was held on November 7, 2017.

In December 2017 ACM formed a wholly owned subsidiary in the Republic of Korea, ACM Research Korea CO., LTD. (“ACM Korea”), to serve customers based in Republic of Korea and perform sales, marketing, research and development activities for new products and solutions.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The consolidated accounts include ACM and its subsidiaries, ACM Shanghai, ACM Wuxi, CleanChip and ACM Korea. Subsidiaries are those entities in which ACM, directly and indirectly, controls more than one half of the voting power. All significant intercompany transactions and balances have been eliminated upon consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the balance sheet date and the reported revenues and expenses during the reported period in the consolidated financial statements and accompanying notes. The Company’s significant accounting estimates and assumptions include, but are not limited to, those used for the valuation and recognition of stock-based compensation arrangements and warrant liability, realization of deferred tax assets, assessment for impairment of long-lived assets, allowance for doubtful accounts, inventory valuation for excess and obsolete inventories, lower of cost and market value or net realizable value of inventories, depreciable lives of property and equipment, accrued warranty, and useful life of intangible assets.

Management evaluates these estimates and assumptions on a regular basis. Actual results could differ from those estimates and assumptions.

Cash and Cash Equivalents

Cash and cash equivalents consist of cash on hand, bank deposits that are unrestricted as to withdrawal and use, and highly liquid investments with an original maturity date of three months or less at the date of purchase. At times, cash deposits may exceed government-insured limits.

Accounts Receivable

Accounts receivable are presented net of an allowance for doubtful accounts. The Company reviews its accounts receivable on a periodic basis and makes general and specific allowances when there is doubt as to the collectability of individual balances. In evaluating the collectability of individual receivable balances, the Company considers many factors, including the age of the balance, a customer’s historical payment history and credit worthiness, and current economic trends. Accounts are written off after all collection efforts have been exhausted. At December 31, 2018 and 2017, the Company, based on a review of its outstanding balances and its customers, determined the allowance for doubtful accounts in the amount of $0 and $0 respectively.

Inventory

Inventory consists of raw materials and related goods, work-in-progress, finished goods, and other consumable materials such as spare parts. Finished goods typically are shipped from the Company’s warehouse within one month of completion.

Inventory was recorded at the lower of cost or net realizable value at December 31, 2018 and 2017.

●

The cost of a general inventory item is determined using the weighted moving average method. Under the weighted moving average method, the Company calculates the new average price of all items of a particular inventory stock each time one or more items of that stock are purchased. The then-current average price of the stock is used for purposes of determining cost of inventory or cost of revenue. The cost of an inventory item purchased specifically for a customized product is determined using the specific identification method. Low-cost consumable materials and packaging materials are expensed as incurred.

●	Market value is determined as the lower of replacement cost or net realizable value.

●	Net realizable value is the estimated selling price, in the ordinary course of business, less estimated costs to complete or dispose.

The Company assesses the recoverability of all inventories quarterly to determine if any adjustments are required. Potential excess or obsolete inventory is written off based on management’s analysis of inventory levels and estimates of future 12-month demand and market conditions.

Property, Plant and Equipment, Net

Property, plant and equipment are recorded at cost less accumulated depreciation and any provision for impairment in value. Depreciation begins when the asset is placed in service and is calculated by using the straight-line method over the estimated useful life of an asset (or, if shorter, over the lease term). Betterments or renewals are capitalized when incurred. Plant, property and equipment is reviewed each year to determine whether any events or circumstances indicate that the carrying amount of the assets may not be recoverable.

Estimated useful lives of assets in the United States are as follows:

Computer and office equipment	3 to 5 years
Furniture and fixtures	5 years
Leasehold improvements	shorter of lease term or estimated useful life

ACM’s subsidiaries follow regulations for depreciation of fixed assets implemented under the PRC’s Enterprise Income Tax Law, which state that the minimum useful lives used for calculating depreciation for fixed assets are as follows:

Manufacturing equipment	for small to medium-sized equipment, 5 years; for large equipment, estimated by purchasing department at time of acceptance
Furniture and fixtures	5 years
Transportation equipment	4 to 5 years
Electronic equipment	3 years
Leasehold improvements	remaining lease term for improvements on leased fixed assets or, for large improvements, estimated useful life; not less than 3 years for non-fixed asset repairs

Expenditures for maintenance and repairs that neither materially add to the value of the property nor appreciably prolong the life of the property are charged to expense as incurred. Upon retirement or sale of an asset, the cost of the asset and the related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is credited or charged to income.

Intangible Assets, Net

Intangible assets consist of software used for finance, manufacturing, and research and development purposes. Assets are valued at cost at the time of acquisition and are amortized over their beneficial periods. If a contract specifies a beneficial period, then the intangible asset is amortized over a term not exceeding the beneficial period. If the contract does not specify a beneficial period, then the intangible asset is amortized over a term not exceeding the valid period specified by local law. If neither the contract nor local law specifies a beneficial period, then the intangible asset is amortized over a period of up to 10 years. Currently, the software that the Company uses is amortized over a two-year period in accordance with the policy described above.

Valuation of Long-Lived Assets

Long-lived assets are evaluated for impairment whenever events or changes in circumstance indicate that the carrying value of the assets may not be fully recoverable or that the useful life of the assets is shorter than the Company had originally estimated. When these events or changes occur, the Company evaluates the impairment of the long-lived assets by comparing the carrying value of the assets to an estimate of future undiscounted cash flows expected to be generated from the use of the assets and their eventual disposition. If the sum of the expected future undiscounted cash flow is less than the carrying value of the assets, the Company recognizes an impairment loss based on the excess of the carrying value over the fair value. No impairment charge was recognized for either of the periods presented.

Leases

Each lease is classified at the inception date as either a capital lease or an operating lease. For the lessee, a lease is a capital lease if any of the following conditions exist: (a) ownership is transferred to the lessee by the end of the lease term; (b) there is a bargain purchase option; (c) the lease term is at least 75% of the property’s estimated remaining economic life; or (d) the present value of the minimum lease payments at the beginning of the lease term is 90% or more of the fair value of the leased property to the leasor at the inception date. A capital lease is accounted for as if there was an acquisition of an asset and an incurrence of an obligation at the inception of the lease. All other leases are accounted for as operating leases. Payments made under operating leases are charged to the consolidated statements of operations and comprehensive income on a straight-line basis over the terms of the underlying lease. The Company had no capital lease for either of the periods presented.

Redeemable Convertible Preferred Stock

The Company recorded each series of convertible preferred stock at fair value on the date of issuance, net of issuance costs. The convertible preferred stock is recorded outside of stockholders’ equity (deficit) because, in the event of certain deemed liquidation events considered not solely within the Company’s control (such as a merger, acquisition, or sale of all or substantially all of the Company’s assets), the convertible preferred stock will become redeemable at the option of the holders. The Company has not adjusted the carrying value of any series of convertible preferred stock to the liquidation preference of such series because it is uncertain whether or when an event would occur that would obligate the Company to pay the liquidation preferences to holders of convertible preferred stock. Subsequent adjustments to the carrying values to the liquidation preferences will be made only when it becomes probable that such a liquidation event will occur.

Revenue Recognition

On January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers, and all the related amendments (the “New Revenue Standard”) to all contracts which were not completed as of January 1, 2018 using the modified retrospective method. The Company does not have open contracts that may result in any changes to revenues applying the New Revenue Standard.

The Company derives revenue principally from the sale of single-wafer wet cleaning equipment. Revenue from contracts with customers is recognized using the following five steps pursuant to the New Revenue Standard:

1. Identify the contract(s) with a customer;

2. Identify the performance obligations in the contract;

3. Determine the transaction price;

4. Allocate the transaction price to the performance obligations in the contract; and

5. Recognize revenue when (or as) the entity satisfies a performance obligation.

A contract contains a promise (or promises) to transfer goods or services to a customer. A performance obligation is a promise (or a group of promises) that is distinct. The transaction price is the amount of consideration a company expects to be entitled from a customer in exchange for providing the goods or services.

The unit of account for revenue recognition is a performance obligation (a good or service). A contract may contain one or more performance obligations. Performance obligations are accounted for separately if they are distinct. A good or service is distinct if the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer, and the good or service is distinct in the context of the contract. Otherwise performance obligations are combined with other promised goods or services until the Company identifies a bundle of goods or services that is distinct. Promises in contracts which do not result in the transfer of a good or service are not performance obligations, as well as those promises that are administrative in nature, or are immaterial in the context of the contract. The Company has addressed whether various goods and services promised to the customer represent distinct performance obligations. The Company applied the guidance of ASC Topic 606-10-25-16 through 18 in order to verify which promises should be assessed for classification as distinct performance obligations. The Company’s contracts with customers include more than one performance obligation. For example, the delivery of a piece of equipment generally includes the promise to install the equipment in the customer’s facility. The Company’s performance obligations in connection with a sale of equipment generally include production, delivery and installation, together with the provision of a warranty.

The transaction price is allocated to all the separate performance obligations in an arrangement. It reflects the amount of consideration to which the Company expects to be entitled in exchange for transferring goods or services, which may include an estimate of variable consideration to the extent that it is probable of not being subject to significant reversals in the future based on the Company’s experience with similar arrangements. The transaction price excludes amounts collected on behalf of third parties, such as sales taxes. This is done on a relative selling price basis using standalone selling prices (“SSP”). The SSP represents the price at which the Company would sell that good or service on a standalone basis at the inception of the contract. Given the requirement for establishing SSP for all performance obligations, if the SSP is directly observable through standalone sales, then such sales should be considered in the establishment of the SSP for the performance obligation. All of the Company’s products were sold in stand-alone arrangements. The Company does not have observable SSPs for most performance obligations as the obligations are not regularly sold on a standalone basis. Production, delivery and installation of a product, together with provision of a warranty, are a single unit of accounting.

Revenue is recognized when the Company satisfies each performance obligation by transferring control of the promised goods or services to the customer. Goods or services can transfer at a point in time (upon the acceptance of the products or upon the arrival at the destination as stipulated in the shipment terms) in a sale arrangement. In general, the Company recognizes revenue when a tool has been demonstrated to meet the customer’s predetermined specifications and is accepted by the customer. If terms of the sale provide for a lapsing customer acceptance period, the Company recognizes revenue as of the earlier of the expiration of the lapsing acceptance period and customer acceptance. In the following circumstances, however, the Company recognizes revenue upon shipment or delivery, when legal title to the tool is passed to a customer as follows:

●	When the customer has previously accepted the same tool with the same specifications and the Company can objectively demonstrate that the tool meets all of the required acceptance criteria;

●	When the sales contract or purchase order contains no acceptance agreement or lapsing acceptance provision and the Company can objectively demonstrate that the tool meets all of the required acceptance criteria;

●	When the customer withholds acceptance due to issues unrelated to product performance, in which case revenue is recognized when the system is performing as intended and meets predetermined specifications; or

●	When the Company’s sales arrangements do not include a general right of return.

The Company offers post-warranty period services, which consist principally of the installation and replacement of parts and small-scale modifications to the equipment. The related revenue and costs of revenue are recognized when parts have been delivered and installed, risk of loss has passed to the customer, and collection is probable. The Company does not expect revenue from extended maintenance service contracts to represent a material portion of its revenue in the future. As such, the Company has concluded that its revenue recognition under the adoption of the New Revenue Standard will remain the same as previously reported and will not have material impacts to its consolidated financial statements.

The Company incurs costs related to the acquisition of its contracts with customers in the form of sales commissions. Sales commissions are paid to third party representatives and distributors. Contractual agreements with these parties outline commission structures and rates to be paid. Generally speaking, the contracts are all individual procurement decisions by the customers and are not for significant periods of time, nor do they include renewal provisions. As such, all contracts have an economic life of significantly less than a year. Accordingly, the Company expenses sales commissions when incurred in accordance with the practical expedient in the New Revenue Standard when the underlying contract asset is less than one year. These costs are recorded within sales and marketing expenses.

Generally, all contracts have expected durations of one year or less. Accordingly, the Company applies the practical expedient allowed in the New Revenue Standard and does not disclose information about remaining performance obligations that have original expected durations of one year or less.

The Company does not incur any costs to fulfill the contracts with customers that are not already reported in compliance with another applicable standard (for example, inventory or plant, property and equipment).

Cost of Revenue

Cost of revenue primarily consists of: direct materials, comprised principally of parts used in assembling equipment, together with crating and shipping costs; direct labor, including salaries and other labor related expenses attributable to the Company’s manufacturing department; and allocated overhead cost, such as personnel cost, depreciation expense, and allocated administrative costs associated with supply chain management and quality assurance activities, as well as shipping insurance premiums.

Research and Development Costs

Research and development costs relating to the development of new products and processes, including significant improvements and refinements to existing products or to the process of supporting customer evaluations of tools, including the development of new tools for evaluation by customers during the product demonstration process, are expensed as incurred.

Shipping and Handling Costs

Shipping and handling costs, which relate to transportation of products to customer locations, are charged to selling and marketing expense. For the year ended December 31, 2018 and 2017, shipping and handling costs included in sales and marketing expenses were $146 and $139 respectively.

Borrowing Costs

Borrowing costs attributable directly to the acquisition, construction or production of qualifying assets that require a substantial period of time to be ready for their intended use or sale are capitalized as part of the cost of those assets. Income earned on temporary investments of specific borrowings pending their expenditure on those assets is deducted from borrowing costs capitalized. All other borrowing costs are recognized in interest expenses in the consolidated statements of operations and comprehensive income in the period in which they are incurred. No borrowing costs were capitalized for the year ended December 31, 2018 or 2017.

Warranty

For each of its products, the Company generally provides a warranty ranging from 12 to 36 months and covering replacement of the product during the warranty period. The Company accounts for the estimated warranty costs as sales and marketing expenses at the time revenue is recognized. Warranty obligations are affected by historical failure rates and associated replacement costs. Utilizing historical warranty cost records, the Company calculates a rate of warranty expenses to revenue to determine the estimated warranty charge. The Company updates these estimated charges on a regular basis. The following table shows changes in the Company’s warranty obligations for the year ended December 31, 2018 and 2017, respectively.

	Year Ended December 31,
	2018			2017
Balance at beginning of period	$	839		$	290
Additions		1,412			736
Utilized		(541	)		(187	)
Balance at end of period	$	1,710		$	839

Government Subsidies

ACM Shanghai has been awarded four subsidies from local and central governmental authorities in the PRC. The first subsidy, which was awarded in October 2008, relates to the development and commercialization of 65-45 nanometer Stress Free Polishing technology. The second subsidy was awarded in April 2009 to fund interest expenses for short-term borrowings. The third subsidy was awarded in January 2014 and relates to the development of Electro Copper Plating technology. The fourth subsidy was awarded in June of 2018, and related to development of Polytetrafluoroethylene. The PRC governmental authorities will provide the majority of the funding, although ACM Shanghai is also required to invest certain amounts in the projects.

The government subsidies contain certain operating conditions and therefore are recorded as long-term liabilities upon receipt. The grant amounts are recognized in the statements of operations and comprehensive income:

●

Government subsidies relating to current expenses are recorded as reductions of those expenses in the periods in which the current expenses are recorded. For the years ended December 31, 2018 and 2017, related government subsidies recognized as reductions of relevant expenses in the consolidated statements of operations and comprehensive income were $1,486 and $3,421 respectively.

●

Government subsidies related to depreciable assets are credited to income over the useful lives of the related assets for which the grant was received. For the years ended December 31, 2018 and 2017, related government subsidies recognized as other income in the consolidated statements of operations and comprehensive income were $144 and $135, respectively.

Unearned government subsidies received are deferred for recognition and recorded as other long-term liabilities (note 9) in the balance sheet until the criteria for such recognition are satisfied.

Stock-based Compensation

ACM grants stock options to employees and non-employee consultants and directors and accounts for those stock-based awards in accordance with FASB ASC Topic 718, Compensation – Stock Compensation, and FASB ASC Subtopic 505-50, Equity-Based Payments to Non-Employees.

Stock-based awards granted to employees are measured at the fair value of the awards on the grant date and are recognized as expenses either (a) immediately on grant, if no vesting conditions are required or (b) using the graded vesting method, net of estimated forfeitures, over the requisite service period. The fair value of stock options is determined using the Black-Scholes valuation model. Stock-based compensation expense, when recognized, is charged to the category of operating expense corresponding to the employee’s service function.

Stock-based awards granted to non-employees are accounted for at the fair value of the awards at the earlier of (a) the date at which a commitment for performance by the non-employee to earn the awards is reached and (b) the date at which the non-employee’s performance is complete. The fair value of such non-employee awards is re-measured at each reporting date using the fair value at each period end until the vesting date. Changes in fair value between the reporting dates are recognized by the graded vesting method.

Operating and Financial Risks

Concentration of Credit Risk

Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents and accounts receivable. The Company deposits and invests its cash with financial institutions that management believes are creditworthy.

The Company is potentially subject to concentrations of credit risks in its accounts receivable. Three customers individually accounted for greater than ten percent of the Company’s revenue for the year ended 2018 and two of those customers individually accounted for greater than ten percent of the Company’s revenue in 2017:

	Year Ended December 31
	2018			2017
Customer A		24.17	%		*
Customer B		23.83			18.10
Customer C		*			12.77
Customer D		*			14.12
Customer E		39.63			10.23

*	Customer accounted for less than 10% of revenue in the period.

Interest Rate Risk

As of December 31, 2018 and 2017, the balance of bank borrowings (note 6) was short-term in nature, matured at various dates within the following year and did not expose the Company to interest rate risk.

Liquidity Risk

The Company’s working capital at December 31, 2018 and 2017 was sufficient to meet its then-current requirements. The Company may, however, require additional cash due to changing business conditions or other future developments, including any investments or acquisitions the Company decides to pursue. In the long run, the Company intends to rely primarily on cash flows from operations and additional borrowings from financial institutions in order to meet its cash needs. If those sources are insufficient to meet cash requirements, the Company may seek to issue additional debt or equity.

Country Risk

The Company has significant investments in the PRC. The operating results of the Company may be adversely affected by changes in the political and social conditions in the PRC and by changes in Chinese government policies with respect to laws and regulations, anti-inflationary measures, currency conversion and remittance abroad, and rates and methods of taxation, among other things.

Foreign Currency Risk and Translation

The Company’s consolidated financial statements are presented in U.S. dollars, which is the Company’s reporting currency, while the functional currency of ACM’s subsidiaries is the Chinese Renminbi (“RMB”), and the Korean Won. Changes in the relative values of U.S. dollars and Chinese RMB affect the Company’s reported levels of revenues and profitability as the results of its operations are translated from RMB into U.S. dollars for reporting purposes. Because the Company has not engaged in any hedging activities, it cannot predict the impact of future exchange rate fluctuations on the results of its operations and it may experience economic losses as a result of foreign currency exchange rate fluctuations.

Transactions of ACM’s subsidiaries involving foreign currencies are recorded in functional currency according to the rate of exchange prevailing on the date when the transaction occurs. The ending balances of the Company’s foreign currency accounts are converted into functional currency using the rate of exchange prevailing at the end of each reporting period. Net gains and losses resulting from foreign exchange transactions are included in the consolidated statements of operations and comprehensive income. Total exchange gain (loss) was ($979) and $1,052 for the years ended December 31, 2018 and 2017.

In accordance with FASB ASC Topic 830, Foreign Currency Matters, the Company translates assets and liabilities into U.S. dollars from RMB or Korean Won using the rate of exchange prevailing at the applicable balance sheet date and the consolidated statements of operations and comprehensive income and consolidated statements of cash flows are translated at an average rate during the reporting period. Adjustments resulting from the translation are recorded in stockholders’ (deficit) equity as part of accumulated other comprehensive income (loss). Any differences between the initially recorded amount and the settlement amount are recorded as a gain or loss on foreign currency transaction in the consolidated statements of operations and comprehensive income.

Translations of amounts from RMB and Korean Won into U.S. dollars were made at the following exchange rates for the respective dates and periods:

Consolidated balance sheets:
At December 31, 2018	RMB 6.8634 to $1.00
At December 31, 2017	RMB 6.5359 to $1.00
At December 31, 2018	KRW 1,114.83 to $1.00
At December 31, 2017	No transactions in Korean Won

Consolidated statements of operations and comprehensive income:
Year ended December 31, 2018	RMB 6.6181 to $1.00
Year ended December 31, 2017	RMB 6.7522 to $1.00
Year ended December 31, 2018	KRW 1,100.11 to $1.00
Year ended December 31, 2017	No transactions in Korean Won

Income Taxes

The Company accounts for income taxes using the liability method whereby deferred tax asset and liability account balances are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company provides a valuation allowance, if necessary, to reduce deferred tax assets to their estimated realizable values.

In evaluating the ability to recover its deferred income tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. In the event the Company determines that it would be able to realize its deferred income tax assets in the future in excess of their net recorded amount, it would make an adjustment to the valuation allowance that would reduce the provision for income taxes. Conversely, in the event that all or part of the net deferred tax assets are determined not to be realizable in the future, an adjustment to the valuation allowance would be charged to earnings in the period such determination is made.

Tax benefits related to uncertain tax positions are recognized when it is more likely than not that a tax position will be sustained during an audit. Interest and penalties related to unrecognized tax benefits are included within the provision for income tax.

Basic and Diluted Net Income (Loss) per Common Share

Basic and diluted net income (loss) per common share is calculated as follows:

	For the Year Ended December 31
	2018		2017
Numerator:
Net income (loss)	$	6,574	$	(872	)
Net loss attributable to non-controlling interest		-		(554	)
Net income (loss) attributable to ACM, basic and diluted		6,574	$	(318	)
Denominator:
Weighted average shares outstanding, basic		15,788,460		6,865,390
Effect of dilutive securities		2,123,645		-
Weighted average shares outstanding, diluted		17,912,105		6,865,390
Net income (loss) attributable to ACM per common share:
Basic	$	0.42	$	(0.05	)
Diluted	$	0.37	$	(0.05	)

Basic and diluted net income (loss) per common share is presented using the two-class method, which allocates undistributed earnings to common stock and any participating securities according to dividend rights and participation rights on a proportionate basis. Under the two-class method, basic net income (loss) per common share is computed by dividing the sum of distributed and undistributed earnings attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Shares of ACM’s Series A, B, C, D, E and F convertible preferred stock are participating securities, as the holders are entitled to participate in and receive the same dividends as may be declared for common stockholders on a pro-rata, if-converted basis.

ACM has been authorized to issue Class A and Class B common stock since redomesticating in Delaware in November 2016. The two classes of common stock are substantially identical in all material respects, except for voting rights. Since ACM did not declare any dividends during the years ended December 31, 2018 and 2017, the net income (loss) per common share attributable to each class is the same under the “two-class” method. As such, the two classes of common stock have been presented on a combined basis in the consolidated statements of operations and comprehensive income (loss) and in the above computation of net income (loss) per common share.

Diluted net income (loss) per common share reflects the potential dilution from securities that could share in ACM’s earnings. All potential dilutive securities, including potentially dilutive convertible preferred stocks and stock options, if any, were excluded from the computation of dilutive net loss per common share for the years ended December 31, 2018 and 2017, as their effects are antidilutive due to our net loss for those periods. The potentially dilutive securities that were not included in the calculation of diluted net income per share in the periods presented where their inclusion would be anti-dilutive are as follows:

	Year Ended December 31
	2018		2017
Stock options		3,715,779		3,372,292
Warrant		80,000		477,502
		3,795,779		3,849,794

Comprehensive Income (Loss) Attributable to the Company

The Company applies FASB ASC Topic 220, Comprehensive Income, which establishes standards for the reporting and display of comprehensive income or loss, requiring its components to be reported in a financial statement with the same prominence as other financial statements. The comprehensive income (loss) attributable to the Company was $5,595 and $(31) for the years ended December 31, 2018 and 2017, respectively.

Appropriated Retained Earnings

The income of ACM’s PRC subsidiaries is distributable to their shareholders after transfers to reserves as required under relevant PRC laws and regulations and the subsidiaries’ Articles of Association. As stipulated by the relevant laws and regulations in the PRC, the PRC subsidiaries are required to maintain reserves, including reserves for statutory surpluses and public welfare funds that are not distributable to shareholders. A PRC subsidiary’s appropriations to the reserves are approved by its board of directors. At least 10% of annual statutory after-tax profits, as determined in accordance with PRC accounting standards and regulations, is required to be allocated to the statutory surplus reserves. If the cumulative total of the statutory surplus reserves reaches 50% of a PRC subsidiary’s registered capital, any further appropriation is optional.

Statutory surplus reserves may be used to offset accumulated losses or to increase the registered capital of a PRC subsidiary, subject to approval from the relevant PRC authorities, and are not available for dividend distribution to the subsidiary’s shareholders. The PRC subsidiaries are prohibited from distributing dividends unless any losses from prior years have been offset. Except for offsetting prior years’ losses, however, statutory surplus reserves must be maintained at a minimum of 25% of share capital after such usage. No retained earnings of either PRC subsidiary had been appropriated to statutory surplus reserves as the PRC subsidiaries recorded accumulated losses as of December 31, 2018 and 2017.

Fair Value of Financial Instruments

Under the FASB’s authoritative guidance on fair value measurements, fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. In determining the fair value, the Company uses various methods including market, income and cost approaches. Based on these approaches, the Company often utilizes certain assumptions that market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs can be readily observable, market corroborated or generally unobservable inputs. The Company uses valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Based on observability of the inputs used in the valuation techniques, the Company is required to provide the following information according to the fair value hierarchy. The fair value hierarchy ranks the quality and reliability of the information used to determine fair values. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three categories:

Level 1: Valuations for assets and liabilities traded in active exchange markets. Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities.

Level 2: Valuations for assets and liabilities traded in less active dealer or broker markets. Valuations are obtained from third party pricing services for identical or similar assets or liabilities.

Level 3: Valuations for assets and liabilities that are derived from other valuation methodologies, including option pricing models, discounted cash flow models and similar techniques, and not based on market exchange, dealer or broker traded transactions. Level 3 valuations incorporate certain unobservable assumptions and projections in determining the fair value assigned to such assets.

All transfers between fair value hierarchy levels are recognized by the Company at the end of each reporting period. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. The inputs or methodology used for valuing financial instruments are not necessarily an indication of the risks associated with investment in those instruments.

Fair Value Measured or Disclosed on a Recurring Basis

Short-term borrowings—Interest rates under the borrowing agreements with the lending parties were determined based on the prevailing interest rates in the market. The Company classifies the valuation techniques that use these inputs as Level 2 fair value measurement.

Warrant liability—The fair value of the warrant liability derives from the Black-Scholes valuation model which incorporates certain unobservable assumptions (Note 8). The Company classifies the valuation techniques that use these inputs as Level 3 fair value measurement.

Other financial items for disclosure purpose—The fair value of other financial items of the Company for disclosure purpose, including cash and cash equivalents, accounts receivable, other receivables, other current assets, accounts payable, advances from customers, and other payables and accrued expenses, approximate their carrying value due to their short-term nature.

As of December 31, 2018 and 2017, information about inputs into the fair value measurement of the Company’s liabilities that are measured and recorded at fair value on a recurring basis in periods subsequent to their initial recognition is as follows:

	Fair Value Measurement at Reporting Date Using
	Quoted Prices in Active Markets for Identical Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
	(in thousands)
As of December 31, 2018:
Liabilities:
Short-term borrowings	$	-	$	9,447	$	-	$	9,447
	$	-	$	9,447	$	-	$	9,447

As of December 31, 2017:
Liabilities:
Short-term borrowings	$	-	$	5,095	$	-	$	5,095
Warrant liability		-		-		3,079		3,079
	$	-	$	5,095	$	3,079	$	8,174

Fair Value Measured on a Non-Recurring Basis

The Company reviews long-lived assets for impairment annually or more frequently if events or changes in circumstances indicate the possibility of impairment. Long-lived assets are measured at fair value on a nonrecurring basis when there is an indicator of impairment, and they are recorded at fair value only when impairment is recognized. In determining the fair value, the Company used projections of cash flows directly associated with, and which are expected to arise as a direct result of, the use and eventual disposition of the assets. This approach required significant judgments including the Company’s projected net cash flows, which were derived using the most recent available estimate for the reporting unit containing the assets tested. Several key assumptions included periods of operation, projections of product pricing, production levels, product costs, market supply and demand, and inflation.

Reclassification of Accounts

Certain prior year’s amounts have been reclassified to conform to current year presentations. There was no change to previously reported stockholders’ deficit or net income.

Recently Adopted Accounting Pronouncements

In May 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”), which provides guidance on determining which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting under Topic 718. The amendments in this ASU are effective for all entities for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted, including adoption in any interim period, for (1) public business entities for reporting periods for which financial statements have not yet been issued and (2) all other entities for reporting periods for which financial statements have not yet been made available for issuance. The amendments in this ASU should be applied prospectively to an award modified on or after the adoption date. The adoption of ASU 2017-09 did not have a material impact on the Company’s consolidated financial statements.

In February 2017, the FASB issued ASU No. 2017-05, Other Income—Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (“ASU 2017-05”), which clarifies the scope of nonfinancial asset guidance in Subtopic 610-20. This ASU also clarifies that derecognition of all businesses and nonprofit activities (except those related to conveyances of oil and gas mineral rights or contracts with customers) should be accounted for in accordance with the derecognition and deconsolidation guidance in Subtopic 810-10. The amendments in this ASU also provide guidance on the accounting for so-called “partial sales” of nonfinancial assets within the scope of Subtopic 610-20 and contributions of nonfinancial assets to a joint venture or other noncontrolled investee. The amendments in this ASU are effective for annual reporting reports beginning after December 15, 2017, including interim reporting periods within that reporting period. The adoption of ASU 2017-05 did not have a material impact on the Company’s consolidated financial statements.

In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”), which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The amendments in this ASU do not provide a definition of restricted cash or restricted cash equivalents. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The adoption of ASU 2016-18 did not have a material impact on the Company’s consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”), which addresses the following cash flow issues: (1) debt prepayment or debt extinguishment costs; (2) settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; (3) contingent consideration payments made after a business combination; (4) proceeds from the settlement of insurance claims; (5) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; (6) distributions received from equity method investees; (7) beneficial interests in securitization transactions; and (8) separately identifiable cash flows and application of the predominance principle. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years and are effective for all other entities for fiscal years beginning after December 15, 2018 and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted, including adoption in an interim period. The adoption of ASU 2016-15 did not have material impact on the Company’s consolidated financial statements.

In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” (“ASU 2016-01”). The amendments in this update require all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under the equity method of accounting or those that result in consolidation of the investee). The amendments in this update also require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. In addition, the amendments in this update eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet for public entities. For public business entities, the amendments in ASU 2016-01 are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Except for the early application guidance discussed in ASU 2016-01, early adoption of the amendments in this update is not permitted. The adoption of the ASU 2016-01 did not have a material impact on the Company’s consolidated financial statements.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), which amended the existing accounting standards for revenue recognition. ASU 2014-09 establishes principles for recognizing revenue upon the transfer of promised goods or services to customers, in an amount that reflects the expected consideration received in exchange for those goods or services. ASU 2014-09 and its related clarifying ASUs are effective for annual reporting periods beginning after December 15, 2017 and interim periods within those annual periods.

On January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers, and all the related amendments (the “New Revenue Standard”) to all contracts which were not completed as of January 1, 2018 using the modified retrospective method. The Company does not have open contracts that may result in any changes to revenues applying the New Revenue Standard.

Recent Accounting Pronouncements Not Yet Adopted

In June 2018, the FASB issued ASU 2018-07, Compensation — Stock Compensation (Topic 718) — Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), which simplifies several aspects of the accounting for nonemployee share-based payment transactions resulting from expanding the scope of Topic 718, Compensation--Stock Compensation, to include share-based payment transactions for acquiring goods and services from nonemployees. Some of the areas for simplification apply only to nonpublic entities. ASU 2018-07 specifies that Topic 718 applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. ASU 2018-07 also clarify that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under the New Revenue Standard. ASU 2018-07 is effective for public business entities for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted. The Company does not expect the adoption of ASU 2018-07 to have a material impact on its consolidated financial statements and related disclosures.

In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”), which provides financial statement preparers with an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. The amendments in ASU 2018-02 are effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption of ASU 2018-02 is permitted, including adoption in any interim period for the public business entities for reporting periods for which financial statements have not yet been issued. The amendments in ASU 2018-02 should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. The Company does not expect the adoption of ASU 2018-02 to have a material impact on its consolidated financial statements.

In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”), which addresses the complexity of accounting for certain financial instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. Current accounting guidance creates cost and complexity for entities that issue financial instruments (such as warrants and convertible instruments) with down round features that require fair value measurement of the entire instrument or conversion option. For public business entities, the amendments in Part I of ASU 2017-11 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. For all other entities, the amendments in Part I of ASU 2017-11 are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. The Company is evaluating the impact of the adoption of ASU 2017-11 on its consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which removes Step 2 from the goodwill impairment test. An entity will apply a one-step quantitative test and record the amount of goodwill impairment as the excess of a reporting unit’s carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. ASU 2017-04 does not amend the optional qualitative assessment of goodwill impairment. A business entity that is an SEC filer must adopt the amendments in ASU 2017-04 for its annual or any interim goodwill impairment test in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company is evaluating the impact of the adoption of ASU 2017-04 on its consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”). The amendments in ASU 2016-02 create Topic 842, Leases, and supersede the leases requirements in Topic 840, Leases. Topic 842 specifies the accounting for leases. The objective of Topic 842 is to establish the principles that lessees and lessors shall apply to report useful information to users of financial statements about the amount, timing, and uncertainty of cash flows arising from a lease. The main difference between Topic 842 and Topic 840 is the recognition of lease assets and lease liabilities for those leases classified as operating leases under Topic 840. Topic 842 retains a distinction between finance leases and operating leases. The classification criteria for distinguishing between finance leases and operating leases are substantially similar to the classification criteria for distinguishing between capital leases and operating leases in the previous lease guidance. The result of retaining a distinction between finance leases and operating leases is that under the lessee accounting model in Topic 842, the effect of leases in the statement of comprehensive income and the statement of cash flows is largely unchanged from previous GAAP. The amendments in ASU No. 2016-02 are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years for public business entities. Early application of the amendments in ASU No. 2016-02 is permitted. We will adopt Topic 842 effective January 1, 2019 using a modified retrospective method and will not restate comparative periods. As permitted under the transition guidance, we will carry forward the assessment of whether our contracts contain or are leases, classification of our leases and remaining lease terms. Based on our portfolio of leases as of December 31, 2018, approximately $5 million of lease assets and liabilities will be recognized on our balance sheet upon adoption, primarily relating to real estate. We are substantially complete with our implementation efforts.

Accounts Receivable

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Accounts Receivable

At December 31, 2018 and 2017, accounts receivable consisted of the following:

	December 31,
	2018		2017
Accounts receivable	$	24,608	$	26,762
Less: Allowance for doubtful accounts		-
Total	$	24,608	$	26,762

The Company reviews accounts receivable on a periodic basis and makes general and specific allowances when there is doubt as to the collectability of individual balances. No allowance for doubtful accounts was considered necessary at December 31, 2018 and 2017. At December 31, 2018 and 2017, accounts receivable of $1,457 (RMB 10,000) and $1,805 (RMB 11,800), respectively, were pledged as collateral for borrowings from financial institutions (note 6).

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventory

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Inventory

At December 31, 2018 and 2017, inventory consisted of the following:

	December 31,
	2018		2017
Raw materials	$	12,646	$	6,181
Work in process		9,631		4,328
Finished goods		16,487		4,879
Total inventory, gross		38,764		15,388
Inventory reserve		-		-
Total inventory, net	$	38,764	$	15,388

The Company did not set up any inventory reserve as of December 31, 2018 or 2017 and no inventory was pledged as collateral for borrowings from financial institutions. System shipments of first-tools to an existing or prospective customer, for which ownership does not transfer until customer acceptance, are classified as finished goods inventory and carried at cost until ownership is transferred.

Property, Plant and Equipment, Net

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment, Net

At December 31, 2018 and 2017, property, plant and equipment consisted of the following:

	December 31,
	2018			2017
Manufacturing equipment	$	9,703		$	9,660
Office equipment		512			463
Transportation equipment		184			203
Leasehold improvement		1,379			277
Total cost		11,778			10,603
Less: Total accumulated depreciation		(8,102	)		(8,263	)
Construction in progress		32			-
Total property, plant and equipment, net	$	3,708		$	2,340

Depreciation expense was $350 and $243 for the years ended December 31, 2018 and 2017, respectively.

Short-Term Borrowings

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Short-Term Borrowings

At December 31, 2018 and 2017, short-term borrowings consisted of the following:

	December 31,
	2018		2017
Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on March 5, 2018 with annual interest rate of 5.69%, secured by certain of the Company’s intellectual property and fully repaid on March 5, 2018 .	$	-	$	2,219
Line of credit up to RMB 25,000 from Bank of Shanghai Pudong Branch, due on Various dates of October 2018 with an annual interest rate of 5.66%, guaranteed by the Company’s CEO and fully repaid on May 8, 2018.		-		2,111
Line of credit up to RMB 50,000 from Bank of Shanghai Pudong Branch, due on April 17, 2019 with an annual interest rate of 4.99%, guaranteed by the Company’s CEO.		3,133		-
Line of credit up to RMB 50,000 from Bank of Shanghai Pudong Branch, due on February 14, 2019 with an annual interest rate of 5.15%, guaranteed by the Company’s CEO.		485		-
Line of credit up to RMB 5,000 from Shanghai Rural Commercial Bank, due on November 21, 2018 with an annual interest rate of 5.44%, guaranteed by the Company’s CEO and pledged by accounts receivable (Note 3).		-		765
Line of credit up to RMB 10,000 from Shanghai Rural Commercial Bank, due on January 23, 2019 with an annual interest rate of 5.44%, guaranteed by the Company’s CEO and pledged by accounts receivable (Note 3).		1,457		-
Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on June 6, 2019 with annual interest rate of 5.22%, secured by certain of the Company’s intellectual property and the Company’s CEO.		2,186		-
Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on June 13, 2019 with annual interest rate of 5.22%, secured by certain of the Company’s intellectual property and the Company’s CEO.		2,186
Total	$	9,447	$	5,095

For the years ended December 31, 2018 and 2017, interest expense related to short-term borrowings amounted to $498 and $272 respectively.

Other Payable and Accrued Expenses

12 Months Ended

Dec. 31, 2018

Payables and Accruals [Abstract]

Other Payable and Accrued Expenses

At December 31, 2018 and 2017, other payable and accrued expenses consisted of the following:

	December 31,
	2018		2017
Lease expenses and payable for leasehold improvement due to a related party (note 11)	$	53	$	2,024
Accrued commissions		2,931		836
Accrued warranty		1,710		839
Accrued payroll		626		745
Accrued professional fees		64		60
Accrued machine testing fees		3,076		684
Others		1,950		849
Total	$	10,410	$	6,037

Warrant Liability

12 Months Ended

Dec. 31, 2018

Text Block [Abstract]

Warrant Liability

On December 9, 2016, Shengxin (Shanghai) Management Consulting Limited Partnership (“SMC”), a related party (note 11), delivered RMB 20,124 (approximately $2,981 as of the close of business on such date) in cash (the “SMC Investment”) to ACM Shanghai for potential investment pursuant to terms to be subsequently negotiated

On March 14, 2017, ACM, ACM Shanghai and SMC entered into a securities purchase agreement (the “SMC Agreement”) pursuant to which, in exchange for the SMC Investment, ACM issued to SMC a warrant exercisable, for cash or on a cashless basis, to purchase, at any time on or before May 17, 2023, all, but not less than all, of 397,502 shares of Class A common stock at a price of $7.50 per share.

The warrant issued to SMC, while outstanding as of December 31, 2017, was classified as a liability as it was conditionally puttable in accordance with FASB ASC 480, Distinguishing Liabilities from Equity. The fair value of the warrant was adjusted for changes in fair value at each reporting period but could not be lower than the proceeds of the SMC Investment. The corresponding non-cash gain or loss of the changes in fair value was recorded in earnings. The methodology used to value the warrant was the Black-Scholes valuation model.

On March 30, 2018, ACM entered into a warrant exercise agreement with ACM Shanghai and SMC pursuant to which SMC exercised its warrant in full by issuing to ACM a senior secured promissory note in the principal amount of approximately $3,000. ACM then transferred the SMC note to ACM Shanghai in exchange for an intercompany promissory note of ACM Shanghai in the principal amount of approximately $3,000. Each of the two notes bears interest at a rate of 3.01% per annum and matures on August 17, 2023. As security for its performance of its obligations under its note, SMC granted to ACM Shanghai a security interest in the 397,502 shares of Class A common stock issued to SMC upon its exercise of the warrant. Upon the issuance of 397,502 shares of Class A common stock to SMC, the senior secured promissory note issued to AMC by SMC was offset against the SMC investment.

Other Long-Term Liabilities

12 Months Ended

Dec. 31, 2018

Other Liabilities Disclosure [Abstract]

Other Long-Term Liabilities

Other long-term liabilities represent government subsidies received from PRC governmental authorities for development and commercialization of certain technology but not yet recognized (note 2). As of December 31, 2018 and 2017, other long-term liabilities consisted of the following unearned government subsidies:

	December 31
	2018		2017
Subsidies to Stress Free Polishing project, commenced in 2008 and 2017	$	1,483	$	1,952
Subsidies to Electro Copper Plating project, commenced in 2014		2,860		4,265
Subsidies to Polytetrafluoroethylene, commenced in 2018		178		-
Other		62		-
Total	$	4,583	$	6,217

Equity Method Investment

12 Months Ended

Dec. 31, 2018

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investment

On September 6, 2017, ACM and Ninebell Co., Ltd. (“Ninebell”), a Korean company that is one of the Company’s principal materials suppliers, entered into an ordinary share purchase agreement, effective as of September 11, 2017, pursuant to which Ninebell issued to ACM ordinary shares representing 20% of Ninebell’s post-closing equity for a purchase price of $1,200, and a common stock purchase agreement, effective as of September 11, 2017, pursuant to which ACM issued 133,334 shares of Class A common stock to Ninebell for a purchase price of $1,000 at $7.50 per share. The investment in Ninebell is accounted for under the equity method. Undistributed earnings attributable to ACM’s equity method investment represented $123 and $37 of the consolidated retained earnings at December 31, 2018 and 2017, respectively.

Related Party Balances and Transactions

12 Months Ended

Dec. 31, 2018

Related Party Balances and Transactions

On August 18, 2017, ACM and Ninebell, its equity method investment affiliate (note 10), entered into a loan agreement pursuant to which ACM made an interest-free loan of $946 to Ninebell, payable in 180 days or automatically extended another 180 days if in default. The loan was secured by a pledge of Ninebell’s accounts receivable due from ACM and all money that Ninebell received from ACM. Ninebell repaid the loan in March 2018. ACM purchased materials from Ninebell amounting to $7,785 and $3,704 during the years ended December 31, 2018 and 2017, respectively. As of December 31, 2018 and 2017, accounts payable due to Ninebell were $1,477 and $2,118, respectively, and prepaid to Ninebell for material purchases were $572 and $229, respectively.

In 2007 ACM Shanghai entered into an operating lease agreement with Shanghai Zhangjiang Group Co., Ltd. (“Zhangjiang Group”) to lease manufacturing and office space located in Shanghai, China. An affiliate of Zhangjiang Group holds 787,098 shares of Class A common stock that it acquired in September 2017 for $5,903. Pursuant to the lease agreement, Zhangjiang Group provided $771 to ACM Shanghai for leasehold improvements. In September 2016 the lease agreement was amended to modify payment terms and extend the lease through December 31, 2017. From January 1 to April 25, 2018, ACM Shanghai leased the property on a month-to-month basis. On April 26, 2018, ACM Shanghai entered into a renewed lease with Zhangjiang Group for the period from January 1, 2018 through December 31, 2022. Under the lease, ACM Shanghai would pay a monthly rental fee of approximately RMB 366 (equivalent to $55). The required security deposit is RMB 1,077 (equivalent to $163). The Company incurred leasing expenses under the lease agreement of $620 and $638 during the years ended December 31, 2018 and 2017, respectively. As of December 31, 2018 and 2017, payables to Zhangjiang Group for lease expenses and leasehold improvements recorded as other payables and accrued expenses amounted to $53 and $2,024, respectively (note 7).

On December 9, 2016, ACM Shanghai received the SMC Investment from SMC for potential investment pursuant to terms to be subsequently negotiated (note 8). SMC is a limited partnership incorporated in the PRC, whose partners consist of employees of ACM Shanghai. On March 14, 2017, ACM, ACM Shanghai and SMC entered into a securities purchase agreement (the “SMC Agreement”) pursuant to which, in exchange for the SMC Investment, ACM issued to SMC a warrant exercisable, for cash or on a cashless basis, to purchase, at any time on or before May 17, 2023, all, but not less than all, of 397,502 shares of Class A common stock at a price of $7.50 per share, for a total exercise price of $2,981. On March 30, 2018, SMC exercised the warrant and purchased 397,502 shares of Class A common stock (note 8).

Leases

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Leases

ACM entered into a two-year lease agreement in March 2015 for office and warehouse space of approximately 3,000 square feet for its headquarters in Fremont, California, at a rate of $2 per month. On February 4, 2019, ACM amended the lease agreement to extend the lease term through March 31, 2020 and increase the base rent to $3.3 per month from April 1, 2019 to March 31, 2020 and $3.4 per month from April 1, 2020 to March 31, 2021.

ACM Shanghai entered into an operating lease agreement with Zhangjiang Group (a related party, see Note 11) in 2007 for manufacturing and office space of approximately 63,510 square feet in Shanghai, China. The lease terms and its payment terms are subject to modification and extension with Zhangjiang Group from time to time. The lease with Zhangjiang Group expired on December 31, 2017 and from January 1, 2018 to April 25, 2018 we leased the property on a month-to-month basis. On April 26, 2018, ACM Shanghai entered into a renewed lease with Zhangjiang Group for the period from January 1, 2018 through December 31, 2022. Under the lease, ACM Shanghai would pay a monthly rental fee of approximately RMB 366 (equivalent to $55). The required security deposit is RMB 1,077 (equivalent to $163).

ACM Wuxi leases office space in Wuxi, China, at a rate of less than $1 per month.

In January 2018, ACM Shanghai entered into an operating lease agreement for the second factory in the Pudong region of Shanghai from January 2018 to January 2023. The new facility has a total of 50,000 square feet of available floor space. The monthly rent varies during the term of the lease.

ACM leases its administrative, research and development and manufacturing facilities under various operating leases. Future minimum lease payments under non-cancelable lease agreements as of December 31, 2018 were as follows:

	December 31, 2018
2019	$	1,391
2020		1,371
2021		1,403
2022		1,441
Total	$	5,606

Rent expense was $1867 and $670 for the years ended December 31, 2018 and 2017, respectively.

Common Stock

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Common Stock

ACM is authorized to issue 100,000,000 shares of Class A common stock and 7,303,533 shares of Class B common stock, each with a par value of $0.0001. Each share of Class A common stock is entitled to one vote, and each share of Class B common stock is entitled to twenty votes and is convertible at any time into one share of Class A common stock. Shares of Class A common stock and Class B common stock are treated equally, identically and ratably with respect to any dividends declared by the Board of Directors unless the Board of Directors declares different dividends to the Class A common stock and Class B common stock by getting approval from a majority of common stock holders.

In August 2017 ACM entered into a securities purchase agreement with PDHTI and its subsidiary Pudong Science and Technology (Cayman) Co., Ltd. (“PST”), in which ACM agreed to bid, in an auction process mandated by PRC regulations, to purchase PDHTI’s 10.78% equity interest in ACM Shanghai and to sell shares of Class A common stock to PST. On September 8, 2017, ACM issued 1,119,576 shares of Class A common stock to PST for a purchase price of $7.50 per share, representing an aggregate purchase price of $8,397.

In August 2017 ACM entered into a securities purchase agreement with ZSTVC and its subsidiary Zhangjiang AJ Company Limited (“ZJAJ”), in which ACM agreed to bid, in an auction process mandated by PRC regulations, to purchase ZSTVC’s 7.58% equity interest in ACM Shanghai and to sell shares of Class A common stock to ZJAJ. On September 8, 2017, ACM issued 787,098 shares of Class A common stock to ZJAJ for a purchase price of $7.50 per share, or an aggregate purchase price of $5,903.

In September 2017 ACM issued 133,334 shares of Class A common stock to Ninebell for a purchase price of $7.50 per share, or an aggregate purchase price of $1,000 (note 10).

In November 2017 ACM issued 2,233,000 shares of Class A common stock and received net proceeds of $11,664 from the IPO and concurrently ACM issued an additional 1,333,334 shares of Class A common stock in a private placement for net proceeds of $7,053.

Upon the completion of the IPO on November 2, 2017, the Company issued a five-year warrant (the “Underwriter's Warrant”) to Roth Capital Partners, LLC, the lead underwriter of the IPO, for the purchase of up to 80,000 shares of Class A common stock at an exercise price of $6.16 per share. The Underwriter’s Warrant was immediately exercisable and expires on November 1, 2022. The Underwriter's Warrant is equity classified and its fair value was $137 at the IPO closing date, using the Black Scholes model with the following assumptions: volatility of 28.26%, a dividend rate of 0%, and a risk-free discount rate of 2%.

In September 2017 ACM issued 133,334 shares of Class A common stock to Ninebell for a purchase price of $7.50 per share, or an aggregate purchase price of $1,000 (note 10).

At various dates during 2017, ACM issued 472,889 shares of Class A common stock upon options exercises by certain employees and non-employees. During the year ended December 31, 2018, the Company issued 265,952 shares of Class A common stock upon options exercises by certain employees and non-employees.

On March 30, 2018, SMC exercised its warrant (note 8) and purchased 397,502 shares of Class A common stock.

At December 31, 2018 and 2017, the number of shares of Class A common stock issued and outstanding was 14,110,315 and 12,935,546, respectively. At December 31, 2018 and 2017, the number of shares of Class B common stock issued and outstanding was 1,898,423 and 2,409,738, respectively. During the year ended December 31, 2018, 511,315 shares of Class B common stock were converted into Class A common stock.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

On April 29, 1998, ACM adopted the 1998 Stock Option Plan (the “1998 Plan”). The options issued under the Plan consisted of incentive stock options (“ISOs”) and nonstatutory stock options (“NSOs”) that should be determined at the time of grant. ISOs could be granted only to employees. NSOs could be granted to employees, directors and consultants. The option price of each ISO and each NSO could not be less than 100% or less than 85% of the fair market value of stock price at the time of grant, respectively. The vesting period was to be determined by the Board of Directors for each grant. The total number of shares of common stock reserved under the 1998 Plan, as amended, was 766,667. If any option granted under the 1998 Plan expires or otherwise terminates without having been exercised in full, the shares of common stock subject to that option would become available for re-grant. At March 3, 2014, the 1998 Plan terminated and no further grants under the 1998 Plan could be made thereunder, although certain previously granted options remained outstanding in accordance with their terms.

On December 28, 2016, ACM adopted the 2016 Omnibus Incentive Plan (the “2016 Plan”). Under the 2016 Plan, the aggregate number of shares of Class A common stock that may be issued shall equal the sum of (a) 2,333,334 and (b) an annual increase on the first day of each year beginning in 2018 and ending in 2026 equal to the lesser of (i) 4% of the shares of Class A and Class B common stock outstanding (on an as-converted basis) on the last day of the immediately preceding year and (ii) such smaller number of shares as may be determined by the Board. A maximum of 2,333,334 shares is available for issuance as ISOs under the 2016 Plan. Besides the stock options, the 2016 Plan also authorizes issuance of stock appreciation rights, restricted stock, restricted stock units, and other share-based and cash awards. The 2016 Plan will terminate on December 27, 2026.

Employee Awards

The following table summarizes the Company’s employee share option activities during the year ended December 31, 2018:

	Number of Option Shares			Weighted Average Grant Date Fair Value		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term
Outstanding at December 31, 2016		2,100,377		$	0.54	$	2.03	7.83 years
Granted		140,002			2.28		6.75
Exercised		(174,334	)		0.45		0.75
Expired		(3,752	)		0.54		3.00
Forfeited		(16,677	)		0.54		3.00
Outstanding at December 31, 2017		2,045,616			0.66		2.46	7.57 years
Granted		745,700			1.52		8.12
Exercised		(151,650	)		0.53		2.06
Expired		(4,622	)		0.55		3.00
Forfeited		(131,639	)		0.97		3.87
Outstanding at December 31, 2018		2,503,405			0.91		4.09	7.30 years
Vested and exercisable at December 31, 2018		1,327,189

During the years ended December 31, 2018 and 2017, ACM recognized employee stock-based compensation expense of $712 and $271, respectively. As of December 31, 2018 and 2017, $2,424 and $729, respectively, of total unrecognized employee stock-based compensation expense, net of estimated forfeitures, related to stock-based awards were expected to be recognized over a weighted-average period of 1.62 years and 1.77 years, respectively. Total unrecognized compensation cost may be adjusted for future changes in estimated forfeitures.

The fair value of each option granted to employee is estimated on the grant date using the Black-Scholes valuation model with the following assumptions.

	December 31,
	2018	2017
Fair value of common share(1)	$5.31-13.85	$5.60-7.59
Expected term in years(2)	6.25	6.25
Volatility(3)	39.14% -43.00%	28.62% -29.18%
Risk-free interest rate(4)	2.55%-2.96%	2.21%-2.22%
Expected dividend(5)	0%	0%

(1)	Common stock value was the close market value on December 31, 2018.

(2)	Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110.

(3)	Volatility is calculated based on the historical volatility of ACM’s comparable companies in the period equal to the expected term of each grant.

(4)	Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant.

(5)	Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock.

Non-employee Awards

The following table summarizes the Company’s non-employee share option activities during the year ended December 31, 2018:

	Number of Option Shares			Weighted Average Grant Date Fair Value		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term
Outstanding at December 31, 2016		1,578,565		$	0.51	$	1.58	6.81 years
Granted		196,669			2.25		6.90
Exercised		(298,555	)		0.39		0.93
Expired		(133,336	)		0.45		0.75
Forfeited		(16,667	)		2.58		7.50
Outstanding at December 31, 2017		1,326,676			0.78		2.52	7.54 years
Granted		-			-		-		-
Exercised		(114,302	)		0.43		1.92		-
Expired		-			-		-		-
Forfeited		-			-		-		-
Outstanding at December 31, 2018		1,212,374		$	0.78		2.57	6.66 years
Vested and exercisable at December 31, 2018		946,691

During the years ended December 31, 2018 and 2017, the Company recognized non-employee stock-based compensation expense of $2,651 and $1,351, respectively.

The fair value of each option granted to non-employees is re-measured at each period end until the vesting date using the Black-Scholes valuation model with the following assumptions:

	December 31,
	2018	2017
Fair value of common share(1)	$10.88	$5.25-7.59
Expected term in years(2)	2.58-5.36	3.58-6.25
Volatility(3)	40.24%-45.48%	28.71-29.41 %
Risk-free interest rate(4)	2.39%-2.94%	1.62%-2.43 %
Expected dividend(5)	0%	0%

(1)	Common stock value was the close market value on December 31, 2018.

(2)	Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110.

(3)	Volatility is calculated based on the historical volatility of ACM’s comparable companies in the period equal to the expected term of each grant.

(4)	Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant.

(5)	Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

The following represent components of the income tax expense (benefit) for the years ended December 31, 2018 and 2017:

	Year Ended December 31,
	2018			2017
Current:
U.S. federal	$	-		$	-
U.S. state		-			-
Foreign		(1,149	)		-
Total current tax expense		(1,149	)		-
Deferred:
U.S. federal		-			-
U.S. state		-			-
Foreign		343			(547	)
Total deferred tax income (expense)		343			(547	)
Total income tax expense	$	(806	)	$	(547	)

Tax effects of temporary differences that give rise to significant portions of the Company’s deferred tax assets at December 31, 2018 and 2017 are presented below:

	December 31,
	2018			2017
Deferred tax assets:
Net operating loss carry forwards (offshore)	$	16		$	4,418
Net operating loss carry forwards (U.S.) and credit		4,105			683
Deferred revenue (offshore)		558			656
Accruals (U.S.)		11			18
Reserves and other (offshore)		1,080			495
Stock-based compensation (U.S.)		1,021			453
Property and equipment (U.S.)		1			2
Total gross deferred tax assets		6,792			6,725
Less: valuation allowance		(5,155	)		(5,431	)
Total deferred tax assets		1,637			1,294
Total deferred tax liabilities		-			-
Translation difference		-			-
Deferred tax assets, net	$	1,637		$	1,294

The Company considers all available evidence to determine whether it is more likely than not that some portion or all of the deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become realizable. Management considers the scheduled reversal of deferred tax liabilities (including the impact of available carryback and carry-forward periods), and projected taxable income in assessing the realizability of deferred tax assets. In making such judgments, significant weight is given to evidence that can be objectively verified. Based on all available evidence, a partial valuation allowance has been established against some net deferred tax assets as of December 31, 2018 and 2017, based on estimates of recoverability. While the Company has optimistic plans for its business strategy, it determined that such a valuation allowance was necessary given its historical losses and the uncertainty with respect to its ability to generate sufficient profits from its business model from all tax jurisdictions. In order to fully realize the U.S. deferred tax assets, the Company must generate sufficient taxable income in future periods before the expiration of the deferred tax assets governed by the tax code. The valuation allowance in the U.S. decreased by $278 for the year ended December 31, 2018 and increased $760 for the year ended December 31, 2017. The valuation allowance in China decreased by $2 and decreased by $58 during the years ended December 31, 2018 and 2017, respectively.

The Company did not have any significant temporary differences relating to deferred tax liabilities as of December 31, 2018 or 2017.

As of December 31, 2018 and 2017, the Company had net operating loss carry-forwards of respectively, $15,867 and $20,116 for U.S federal purposes, $714 and $536 for U.S. state purposes and $6,411 for Chinese income tax purposes. Such losses are set to expire in 2019, 2032, and 2019 for U.S. federal, U.S. state and Chinese income tax purposes, respectively.

As of December 31, 2018 and 2017, the Company had research credit carry-forwards of $606 for U.S. federal purposes, and $377 for U.S. state purposes. Such credits are set to expire in 2025 for U.S. federal carry-forwards. There is no expiration date for U.S. state carry-forwards.

A limitation may apply to the use of the U.S. net operating loss and credit carry-forwards, under provisions of the U.S. Internal Revenue Code that would be applicable if ACM experiences an “ownership change.” Should these limitations apply, the carry-forwards would be subject to an annual limitation, resulting in a substantial reduction in the gross deferred tax assets before considering the valuation allowance. As of December 31, 2018 and 2017, the Company had not performed an analysis to determine if its net operating loss and credit carry-forwards would be subject to such limitations.

The Company’s effective tax rate differs from statutory rates of 21% for U.S. federal income tax purposes and 15%-25% for Chinese income tax purpose due to the effects of the valuation allowance and certain permanent differences as it pertains to book-tax differences in the value of client shares received for services. Pursuant to the Corporate Income Tax Law of the PRC, all of the Company’s PRC subsidiaries are liable to PRC Corporate Income Taxes at a rate of 25% except for ACM Shanghai. According to Guoshuihan 2009 No. 203, if an entity is certified as an “advanced and new technology enterprise,” it is entitled to a preferential income tax rate of 15%. ACM Shanghai obtained the certificate of “advanced and new technology enterprise” in 2012 and again in 2016 with an effective period of three years, and the provision for PRC corporate income tax for ACM Shanghai is calculated by applying the income tax rate of 15% for the years ended December 31, 2018 and 2017.

Income tax expense (benefit) for the years ended December 31, 2018 and 2017 differed from the amounts computed by applying the statutory federal income tax rate of 21% and 34%, respectively, to pretax income (loss) as a result of the following:

	Year Ended December 31,
	2018			2017
Effective tax rate reconciliation:
Income tax provision at statutory rate		21.00	%		34.00	%
State taxes, net of Federal benefit		-			-
Foreign rate differential		(20.88	)		6.80
Other permanent difference		15.59			197.7
Effect of tax reform		-			(757	)
Change in valuation allowance		(4.78	)		349.9
Total income tax expense (benefit)		(10.93	%)		(168.65	%)

Tax positions are evaluated in a two-step process. The Company first determines whether it is more likely than not that a tax position will be sustained upon examination. If a tax position meets the more-likely-than-not recognition threshold it is then measured to determine the amount of benefit to recognize in the financial statements. The tax position is measured as the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement. The aggregate changes in the balance of gross unrecognized tax benefits, which excludes interest and penalties, for the years ended December 31, 2018 and 2017, are as follows:

	December 31,
	2018		2017
Beginning balance	$	44	$	44
Increase/(Decrease) of unrecognized tax benefits taken in prior years		-		-
Increase/(Decrease) of unrecognized tax benefits related to current year		-		-
Increase/(Decreases) of unrecognized tax benefits related to settlements		-		-
Reductions to unrecognized tax benefits related to lapsing statute of limitations		-		-
Ending balance	$	44	$	44

The Company files income tax returns in the United States, and state and foreign jurisdictions. The federal, state and foreign income tax returns are under the statute of limitations subject to tax examinations for the tax years ended December 31, 2009 through December 31, 2017. To the extent the Company has tax attribute carry-forwards, the tax years in which the attribute was generated may still be adjusted upon examination by the U.S. Internal Revenue Service, state or foreign tax authorities to the extent utilized in a future period.

The Company had $44 of unrecognized tax benefits as of December 31, 2018 and 2017.

The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2018 and 2017, the Company had $44 of accrued penalties and $44 of accrued penalties related to uncertain tax positions, none of which has been recognized in the Company’s consolidated statements of operations and comprehensive income for the years ended December 31, 2018 and 2017. There were no ongoing examinations by taxing authorities as of December 31, 2018 and 2017.

The Company intends to indefinitely reinvest the PRC earnings outside of the U.S. as of December 31, 2018 and 2017. Thus, deferred taxes are not provided in the U.S. for unremitted earnings in the PRC.

On December 22, 2017, the 2017 Tax Cuts and Jobs Act was enacted into law and the new legislation contains several key tax provisions that affect us, including a one-time mandatory transition tax on accumulated foreign earnings and a reduction of the corporate income tax rate to 21% effective January 1, 2018, among others. We are required to recognize the effect of the tax law changes in the period of enactment, such as determining the transition tax, remeasuring our U.S. deferred tax assets and liabilities as well as reassessing the net realizability of our deferred tax assets and liabilities.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

The Company leases offices under non-cancelable operating lease agreements. The rental expenses were $1,867 and $670 for the years ended December 31, 2018 and 2017, respectively. See note 12 for future minimum lease payments under non-cancelable operating lease agreements with initial terms of one year or more.

The Company did not have any capital commitments during the reported periods.

From time to time the Company is subject to legal proceedings, including claims in the ordinary course of business and claims with respect to patent infringements.

Restricted Net Assets

12 Months Ended

Dec. 31, 2018

Restricted Net Assets

Restricted Net Assets

In accordance with the PRC’s Foreign Enterprise Law, ACM Shanghai and ACM Wuxi are required to make contributions to a statutory surplus reserve (note 2).

As a result of PRC laws and regulations that require annual appropriations of 10% of net after-tax profits to be set aside prior to payment of dividends as a general reserve fund or statutory surplus fund, ACM Shanghai is restricted in its ability to transfer a portion of its net assets to ACM (including any assets received as distributions from ACM Wuxi). Amounts restricted included paid-in capital and statutory reserve funds, as determined pursuant to PRC accounting standards and regulations, were $32,076 and $29,927 as of December 31, 2018 and 2017.

Parent Company Only Condensed Financial Information

12 Months Ended

Dec. 31, 2018

Parent Company Only Condensed Financial Information

Parent Company Only Condensed Financial Information

The Company performed a test on the restricted net assets of consolidated subsidiaries in accordance with Rule 4-08(e)(3) of Regulation S-X of the SEC and concluded that it was applicable for the Company to disclose the financial information for ACM only. Certain information and footnote disclosures generally included in financial statements prepared in accordance with GAAP have been condensed or omitted. The footnote disclosure contains supplemental information relating to the operations of ACM separately.

ACM’s subsidiaries did not pay any dividends to ACM during the periods presented.

ACM did not have significant capital or other commitments, long-term obligations, or guarantees as of December 31, 2018 and 2017.

The following represents condensed unconsolidated financial information of ACM only as of and for the years ended December 31, 2018 and 2017:

CONDENSED BALANCE SHEET

	December 31,
	2018		2017
Assets
Current assets:
Cash and cash equivalents	$	13,161	$	10,874
Accounts Receivable		983		118
Inventory		720		565
Due from intercompany		14,494		12,669
Other receivable		175		50
Total current assets		29,533		24,276
Investment in unconsolidated subsidiaries		26,861		15,476
Due from related party		-		946
Total assets		56,394		40,698
Liabilities and Stockholders’ Equity
Notes payable		-		11
Accounts payable		2,818		739
Other payable		58		47
Income taxes payable		1,193		44
Total liabilities		4,069		841
Total redeemable convertible preferred stocks		-		-
Total stockholders’ equity		52,325		39,857
Total liabilities and stockholders’ equity	$	56,394	$	40,698

CONDENSED STATEMENT OF OPERATIONS

	Year Ended December 31,
	2018			2017
Revenue	$	25,506		$	6,985
Cost of revenue		(23,927	)		(6,394	)
Gross profit		1,579			591
Operating expenses:
Sales and marketing expenses		(301	)		(368	)
General and administrative expenses		(5,083	)		(3,961	)
Research and development expenses		(255	)		(50	)
Loss from operations		(4,060	)		(3,788	)
Equity in earnings of unconsolidated subsidiaries		10,360			3,475
Other income (expense), net		108			-
Interest expense, net		166			(5	)
Income (loss) before income taxes		6,574			(318	)
Income tax expense (benefit)		-			-
Net income (loss)	$	6,574		$	(318	)

CONDENSED STATEMENT OF CASH FLOWS

	Year Ended December 31,
	2018			2017
Net cash used in operating activities	$	(1,189	)	$	(13,848	)
Net cash provided by (used in) investing activities		946			(21,754	)
Net cash provided by financing activities		3,510			38,676
Net increase in cash and cash equivalents		3,267			3,074
Cash and cash equivalents, beginning of year		10,874			7,264
Effect of exchange rate changes on cash and cash equivalents		(980	)		536
Cash and cash equivalents, end of year	$	13,161		$	10,874

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation and Principles of Consolidation

Use of Estimates

Management evaluates these estimates and assumptions on a regular basis. Actual results could differ from those estimates and assumptions.

Cash and cash equivalents

Accounts receivable

Inventory

Inventory was recorded at the lower of cost or net realizable value at December 31, 2018 and 2017.

●

●	Market value is determined as the lower of replacement cost or net realizable value.

●	Net realizable value is the estimated selling price, in the ordinary course of business, less estimated costs to complete or dispose.

Property, Plant and Equipment, Net

Estimated useful lives of assets in the United States are as follows:

Computer and office equipment	3 to 5 years
Furniture and fixtures	5 years
Leasehold improvements	shorter of lease term or estimated useful life

Manufacturing equipment	for small to medium-sized equipment, 5 years; for large equipment, estimated by purchasing department at time of acceptance
Furniture and fixtures	5 years
Transportation equipment	4 to 5 years
Electronic equipment	3 years
Leasehold improvements	remaining lease term for improvements on leased fixed assets or, for large improvements, estimated useful life; not less than 3 years for non-fixed asset repairs

Intangible Assets, Net

Valuation of Long-Lived Assets

Leases

Redeemable Convertible Preferred Stock

Revenue Recognition

1. Identify the contract(s) with a customer;

2. Identify the performance obligations in the contract;

3. Determine the transaction price;

4. Allocate the transaction price to the performance obligations in the contract; and

5. Recognize revenue when (or as) the entity satisfies a performance obligation.

●	When the customer has previously accepted the same tool with the same specifications and the Company can objectively demonstrate that the tool meets all of the required acceptance criteria;

●	When the sales contract or purchase order contains no acceptance agreement or lapsing acceptance provision and the Company can objectively demonstrate that the tool meets all of the required acceptance criteria;

●	When the customer withholds acceptance due to issues unrelated to product performance, in which case revenue is recognized when the system is performing as intended and meets predetermined specifications; or

●	When the Company’s sales arrangements do not include a general right of return.

Cost of Revenue

Research and Development Costs

Shipping and Handling Costs

Borrowing Costs

Warranty

	Year Ended December 31,
	2018			2017
Balance at beginning of period	$	839		$	290
Additions		1,412			736
Utilized		(541	)		(187	)
Balance at end of period	$	1,710		$	839

Government Subsidies

●

Unearned government subsidies received are deferred for recognition and recorded as other long-term liabilities (note 9) in the balance sheet until the criteria for such recognition are satisfied.

Stock-based Compensation

Operating and Financial Risks

Concentration of Credit Risk

	Year Ended December 31
	2018			2017
Customer A		24.17	%		*
Customer B		23.83			18.10
Customer C		*			12.77
Customer D		*			14.12
Customer E		39.63			10.23

*	Customer accounted for less than 10% of revenue in the period.

Interest Rate Risk

Liquidity Risk

Country Risk

Foreign Currency Risk and Translation

Translations of amounts from RMB and Korean Won into U.S. dollars were made at the following exchange rates for the respective dates and periods:

Consolidated balance sheets:
At December 31, 2018	RMB 6.8634 to $1.00
At December 31, 2017	RMB 6.5359 to $1.00
At December 31, 2018	KRW 1,114.83 to $1.00
At December 31, 2017	No transactions in Korean Won

Consolidated statements of operations and comprehensive income:
Year ended December 31, 2018	RMB 6.6181 to $1.00
Year ended December 31, 2017	RMB 6.7522 to $1.00
Year ended December 31, 2018	KRW 1,100.11 to $1.00
Year ended December 31, 2017	No transactions in Korean Won

Income Taxes

Basic and Diluted Net Income (Loss) per Common Share

Basic and diluted net income (loss) per common share is calculated as follows:

	For the Year Ended December 31
	2018		2017
Numerator:
Net income (loss)	$	6,574	$	(872	)
Net loss attributable to non-controlling interest		-		(554	)
Net income (loss) attributable to ACM, basic and diluted		6,574	$	(318	)
Denominator:
Weighted average shares outstanding, basic		15,788,460		6,865,390
Effect of dilutive securities		2,123,645		-
Weighted average shares outstanding, diluted		17,912,105		6,865,390
Net income (loss) attributable to ACM per common share:
Basic	$	0.42	$	(0.05	)
Diluted	$	0.37	$	(0.05	)

	Year Ended December 31
	2018		2017
Stock options		3,715,779		3,372,292
Warrant		80,000		477,502
		3,795,779		3,849,794

Comprehensive Income (Loss) Attributable to the Company

Appropriated Retained Earnings

Fair Value of Financial Instruments

Fair Value Measured or Disclosed on a Recurring Basis

	Fair Value Measurement at Reporting Date Using
	Quoted Prices in Active Markets for Identical Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
	(in thousands)
As of December 31, 2018:
Liabilities:
Short-term borrowings	$	-	$	9,447	$	-	$	9,447
	$	-	$	9,447	$	-	$	9,447

As of December 31, 2017:
Liabilities:
Short-term borrowings	$	-	$	5,095	$	-	$	5,095
Warrant liability		-		-		3,079		3,079
	$	-	$	5,095	$	3,079	$	8,174

Fair Value Measured on a Non-Recurring Basis

Reclassification of Accounts

Certain prior year’s amounts have been reclassified to conform to current year presentations. There was no change to previously reported stockholders’ deficit or net income.

Recent Accounting Pronouncements

Recent Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Property, plant, and equipment, net

Computer and office equipment	3 to 5 years
Furniture and fixtures	5 years
Leasehold improvements	shorter of lease term or estimated useful life

Manufacturing equipment	for small to medium-sized equipment, 5 years; for large equipment, estimated by purchasing department at time of acceptance
Furniture and fixtures	5 years
Transportation equipment	4 to 5 years
Electronic equipment	3 years
Leasehold improvements	remaining lease term for improvements on leased fixed assets or, for large improvements, estimated useful life; not less than 3 years for non-fixed asset repairs

Warranty obligations

	Year Ended December 31,
	2018			2017
Balance at beginning of period	$	839		$	290
Additions		1,412			736
Utilized		(541	)		(187	)
Balance at end of period	$	1,710		$	839

Concentration of credit risks

	Year Ended December 31
	2018			2017
Customer A		24.17	%		*
Customer B		23.83			18.10
Customer C		*			12.77
Customer D		*			14.12
Customer E		39.63			10.23

*	Customer accounted for less than 10% of revenue in the period.

Foreign Currency Risk and Translation

Consolidated balance sheets:
At December 31, 2018	RMB 6.8634 to $1.00
At December 31, 2017	RMB 6.5359 to $1.00
At December 31, 2018	KRW 1,114.83 to $1.00
At December 31, 2017	No transactions in Korean Won

Consolidated statements of operations and comprehensive income:
Year ended December 31, 2018	RMB 6.6181 to $1.00
Year ended December 31, 2017	RMB 6.7522 to $1.00
Year ended December 31, 2018	KRW 1,100.11 to $1.00
Year ended December 31, 2017	No transactions in Korean Won

Calculation of Basic and Diluted Net Income (Loss) per Common Share

	For the Year Ended December 31
	2018		2017
Numerator:
Net income (loss)	$	6,574	$	(872	)
Net loss attributable to non-controlling interest		-		(554	)
Net income (loss) attributable to ACM, basic and diluted		6,574	$	(318	)
Denominator:
Weighted average shares outstanding, basic		15,788,460		6,865,390
Effect of dilutive securities		2,123,645		-
Weighted average shares outstanding, diluted		17,912,105		6,865,390
Net income (loss) attributable to ACM per common share:
Basic	$	0.42	$	(0.05	)
Diluted	$	0.37	$	(0.05	)

Antidilutive securities

	Year Ended December 31
	2018		2017
Stock options		3,715,779		3,372,292
Warrant		80,000		477,502
		3,795,779		3,849,794

Fair Value Measured or Disclosed on a Recurring Basis

	Fair Value Measurement at Reporting Date Using
	Quoted Prices in Active Markets for Identical Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
	(in thousands)
As of December 31, 2018:
Liabilities:
Short-term borrowings	$	-	$	9,447	$	-	$	9,447
	$	-	$	9,447	$	-	$	9,447

As of December 31, 2017:
Liabilities:
Short-term borrowings	$	-	$	5,095	$	-	$	5,095
Warrant liability		-		-		3,079		3,079
	$	-	$	5,095	$	3,079	$	8,174

- Definition

Tabular disclosure of all significant concentrations of risk, including credit risk and market risk, arising from all financial instruments (as defined), whether from an individual counterparty or groups of counterparties. The disclosure concerning concentrations of risk may consist of the following information: (1) for concentrations of credit risk disclosure may include: (a) information about the (shared) activity, region, or economic characteristic that identifies the concentration, (b) the maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity, (c) the policy of requiring collateral or other security to support financial instruments subject to credit risk, information about the entity's access to that collateral or other security, and the nature and a brief description of the collateral or other security supporting those financial instruments, and (d) the policy of entering into master netting arrangements to mitigate the credit risk of financial instruments, information about the arrangements for which the entity is a party, and a brief description of the terms of those arrangements, including the extent to which they would reduce the entity's maximum amount of loss due to credit risk and (2) for disclosure of quantitative information about the market risks of financial instruments that is consistent with the way the company manages or adjusts those risks, disclosure may include: (a) more details about current positions and perhaps activity during the period, (b) the hypothetical effects on comprehensive income (or net assets), or annual income, of several possible changes in market prices, (c) a gap analysis of interest rate re-pricing or maturity dates, (d) the duration of the financial instruments, (e) the entity's value at risk from derivatives and from other positions at the end of the reporting period and the average value at risk during the year, or (f) other ways of reporting quantitative information as internally developed.

+ References + Details

Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Accounts Receivable

	December 31,
	2018		2017
Accounts receivable	$	24,608	$	26,762
Less: Allowance for doubtful accounts		-
Total	$	24,608	$	26,762

Inventory (Tables)

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Inventory

	December 31,
	2018		2017
Raw materials	$	12,646	$	6,181
Work in process		9,631		4,328
Finished goods		16,487		4,879
Total inventory, gross		38,764		15,388
Inventory reserve		-		-
Total inventory, net	$	38,764	$	15,388

Property, Plant and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, plant and equipment

	December 31,
	2018			2017
Manufacturing equipment	$	9,703		$	9,660
Office equipment		512			463
Transportation equipment		184			203
Leasehold improvement		1,379			277
Total cost		11,778			10,603
Less: Total accumulated depreciation		(8,102	)		(8,263	)
Construction in progress		32			-
Total property, plant and equipment, net	$	3,708		$	2,340

Short-Term Borrowings (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Short-term borrowing

	December 31,
	2018		2017
Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on March 5, 2018 with annual interest rate of 5.69%, secured by certain of the Company’s intellectual property and fully repaid on March 5, 2018 .	$	-	$	2,219
Line of credit up to RMB 25,000 from Bank of Shanghai Pudong Branch, due on Various dates of October 2018 with an annual interest rate of 5.66%, guaranteed by the Company’s CEO and fully repaid on May 8, 2018.		-		2,111
Line of credit up to RMB 50,000 from Bank of Shanghai Pudong Branch, due on April 17, 2019 with an annual interest rate of 4.99%, guaranteed by the Company’s CEO.		3,133		-
Line of credit up to RMB 50,000 from Bank of Shanghai Pudong Branch, due on February 14, 2019 with an annual interest rate of 5.15%, guaranteed by the Company’s CEO.		485		-
Line of credit up to RMB 5,000 from Shanghai Rural Commercial Bank, due on November 21, 2018 with an annual interest rate of 5.44%, guaranteed by the Company’s CEO and pledged by accounts receivable (Note 3).		-		765
Line of credit up to RMB 10,000 from Shanghai Rural Commercial Bank, due on January 23, 2019 with an annual interest rate of 5.44%, guaranteed by the Company’s CEO and pledged by accounts receivable (Note 3).		1,457		-
Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on June 6, 2019 with annual interest rate of 5.22%, secured by certain of the Company’s intellectual property and the Company’s CEO.		2,186		-
Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on June 13, 2019 with annual interest rate of 5.22%, secured by certain of the Company’s intellectual property and the Company’s CEO.		2,186
Total	$	9,447	$	5,095

Other Payable and Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2018

Payables and Accruals [Abstract]

Other payable and accrued expenses

	December 31,
	2018		2017
Lease expenses and payable for leasehold improvement due to a related party (note 11)	$	53	$	2,024
Accrued commissions		2,931		836
Accrued warranty		1,710		839
Accrued payroll		626		745
Accrued professional fees		64		60
Accrued machine testing fees		3,076		684
Others		1,950		849
Total	$	10,410	$	6,037

Other Long-Term Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Other Liabilities Disclosure [Abstract]

Other long-term liabilities

	December 31
	2018		2017
Subsidies to Stress Free Polishing project, commenced in 2008 and 2017	$	1,483	$	1,952
Subsidies to Electro Copper Plating project, commenced in 2014		2,860		4,265
Subsidies to Polytetrafluoroethylene, commenced in 2018		178		-
Other		62		-
Total	$	4,583	$	6,217

Leases (Tables)

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Summary of Future Minimum Lease Payments under Non-cancelable Lease Agreements

	December 31, 2018
2019	$	1,391
2020		1,371
2021		1,403
2022		1,441
Total	$	5,606

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Employee Stock Option [Member]

Summary of Share Option Activities

	Number of Option Shares			Weighted Average Grant Date Fair Value		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term
Outstanding at December 31, 2016		2,100,377		$	0.54	$	2.03	7.83 years
Granted		140,002			2.28		6.75
Exercised		(174,334	)		0.45		0.75
Expired		(3,752	)		0.54		3.00
Forfeited		(16,677	)		0.54		3.00
Outstanding at December 31, 2017		2,045,616			0.66		2.46	7.57 years
Granted		745,700			1.52		8.12
Exercised		(151,650	)		0.53		2.06
Expired		(4,622	)		0.55		3.00
Forfeited		(131,639	)		0.97		3.87
Outstanding at December 31, 2018		2,503,405			0.91		4.09	7.30 years
Vested and exercisable at December 31, 2018		1,327,189

Summary of Assumptions used to Determine Fair Value of Share Options Granted

	December 31,
	2018	2017
Fair value of common share(1)	$5.31-13.85	$5.60-7.59
Expected term in years(2)	6.25	6.25
Volatility(3)	39.14% -43.00%	28.62% -29.18%
Risk-free interest rate(4)	2.55%-2.96%	2.21%-2.22%
Expected dividend(5)	0%	0%

Non Employee Awards [Member]

Summary of Share Option Activities

	Number of Option Shares			Weighted Average Grant Date Fair Value		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term
Outstanding at December 31, 2016		1,578,565		$	0.51	$	1.58	6.81 years
Granted		196,669			2.25		6.90
Exercised		(298,555	)		0.39		0.93
Expired		(133,336	)		0.45		0.75
Forfeited		(16,667	)		2.58		7.50
Outstanding at December 31, 2017		1,326,676			0.78		2.52	7.54 years
Granted		-			-		-		-
Exercised		(114,302	)		0.43		1.92		-
Expired		-			-		-		-
Forfeited		-			-		-		-
Outstanding at December 31, 2018		1,212,374		$	0.78		2.57	6.66 years
Vested and exercisable at December 31, 2018		946,691

Summary of Assumptions used to Determine Fair Value of Share Options Granted

	December 31,
	2018	2017
Fair value of common share(1)	$10.88	$5.25-7.59
Expected term in years(2)	2.58-5.36	3.58-6.25
Volatility(3)	40.24%-45.48%	28.71-29.41 %
Risk-free interest rate(4)	2.39%-2.94%	1.62%-2.43 %
Expected dividend(5)	0%	0%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Taxes Tables Abstract

Components of the income tax benefit (expense)

	Year Ended December 31,
	2018			2017
Current:
U.S. federal	$	-		$	-
U.S. state		-			-
Foreign		(1,149	)		-
Total current tax expense		(1,149	)		-
Deferred:
U.S. federal		-			-
U.S. state		-			-
Foreign		343			(547	)
Total deferred tax income (expense)		343			(547	)
Total income tax expense	$	(806	)	$	(547	)

Deferred tax assets

	December 31,
	2018			2017
Deferred tax assets:
Net operating loss carry forwards (offshore)	$	16		$	4,418
Net operating loss carry forwards (U.S.) and credit		4,105			683
Deferred revenue (offshore)		558			656
Accruals (U.S.)		11			18
Reserves and other (offshore)		1,080			495
Stock-based compensation (U.S.)		1,021			453
Property and equipment (U.S.)		1			2
Total gross deferred tax assets		6,792			6,725
Less: valuation allowance		(5,155	)		(5,431	)
Total deferred tax assets		1,637			1,294
Total deferred tax liabilities		-			-
Translation difference		-			-
Deferred tax assets, net	$	1,637		$	1,294

Income tax rate

	Year Ended December 31,

	2018			2017
Effective tax rate reconciliation:
Income tax provision at statutory rate		21.00	%		34.00	%
State taxes, net of Federal benefit		-			-
Foreign rate differential		(20.88	)		6.80
Other permanent difference		15.59			197.7
Effect of tax reform		-			(757	)
Change in valuation allowance		(4.78	)		349.9
Total income tax expense (benefit)		(10.93	%)		(168.65	%)

Aggregate changes in the balance of gross unrecognized tax benefits

	December 31,
	2018		2017
Beginning balance	$	44	$	44
Increase/(Decrease) of unrecognized tax benefits taken in prior years		-		-
Increase/(Decrease) of unrecognized tax benefits related to current year		-		-
Increase/(Decreases) of unrecognized tax benefits related to settlements		-		-
Reductions to unrecognized tax benefits related to lapsing statute of limitations		-		-
Ending balance	$	44	$	44

Parent Company Only Condensed Financial Information (Tables)

12 Months Ended

Dec. 31, 2018

Parent Company Only Condensed Financial Information Tables Abstract

Condensed balance sheet

	December 31,
	2018		2017
Assets
Current assets:
Cash and cash equivalents	$	13,161	$	10,874
Accounts Receivable		983		118
Inventory		720		565
Due from intercompany		14,494		12,669
Other receivable		175		50
Total current assets		29,533		24,276
Investment in unconsolidated subsidiaries		26,861		15,476
Due from related party		-		946
Total assets		56,394		40,698
Liabilities and Stockholders’ Equity
Notes payable		-		11
Accounts payable		2,818		739
Other payable		58		47
Income taxes payable		1,193		44
Total liabilities		4,069		841
Total redeemable convertible preferred stocks		-		-
Total stockholders’ equity		52,325		39,857
Total liabilities and stockholders’ equity	$	56,394	$	40,698

Condensed statement of operations

	Year Ended December 31,
	2018			2017
Revenue	$	25,506		$	6,985
Cost of revenue		(23,927	)		(6,394	)
Gross profit		1,579			591
Operating expenses:
Sales and marketing expenses		(301	)		(368	)
General and administrative expenses		(5,083	)		(3,961	)
Research and development expenses		(255	)		(50	)
Loss from operations		(4,060	)		(3,788	)
Equity in earnings of unconsolidated subsidiaries		10,360			3,475
Other income (expense), net		108			-
Interest expense, net		166			(5	)
Income (loss) before income taxes		6,574			(318	)
Income tax expense (benefit)		-			-
Net income (loss)	$	6,574		$	(318	)

Condensed statement of cash flows

	Year Ended December 31,
	2018			2017
Net cash used in operating activities	$	(1,189	)	$	(13,848	)
Net cash provided by (used in) investing activities		946			(21,754	)
Net cash provided by financing activities		3,510			38,676
Net increase in cash and cash equivalents		3,267			3,074
Cash and cash equivalents, beginning of year		10,874			7,264
Effect of exchange rate changes on cash and cash equivalents		(980	)		536
Cash and cash equivalents, end of year	$	13,161		$	10,874

Description of Business (Details Narrative)	Dec. 31, 2017
ACM Shanghai [Member]
Outstanding equity interest	100.00%

Summary of Significant Accounting Policies (Details)	12 Months Ended
Summary of Significant Accounting Policies (Details)	Dec. 31, 2018
Computer and office equipment [Member]
Useful lives	3 to 5 years
Computer and office equipment [Member] \| ACM Subsidiaries
Useful lives	for small to medium-sized equipment, 5 years; for large equipment, estimated by purchasing department at time of acceptance
Furniture and fixtures
Useful lives	5 years
Furniture and fixtures \| ACM Subsidiaries
Useful lives	5 years
Leasehold improvements
Useful lives	shorter of lease term or estimated useful life
Leasehold improvements \| ACM Subsidiaries
Useful lives	remaining lease term for improvements on leased fixed assets or, for large improvements, estimated useful life; not less than 3 years for non-fixed asset repairs
Transportation equipment \| ACM Subsidiaries
Useful lives	4 to 5 years
Electronic equipment \| ACM Subsidiaries
Useful lives	3 years

Summary of Significant Accounting Policies (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies
Beginning	$ 839	$ 290
Additions	1,412	736
Utilized	(541)	(187)
Ending	$ 1,710	$ 839

Summary of Significant Accounting Policies (Details 2)	12 Months Ended
Summary of Significant Accounting Policies (Details 2)	Dec. 31, 2018	Dec. 31, 2017
Customer A
Concentration of credit risk	24.17%	0.00%
Customer B
Concentration of credit risk	23.83%	18.10%
Customer C
Concentration of credit risk	0.00%	12.77%
Customer D
Concentration of credit risk	0.00%	14.12%
Customer E
Concentration of credit risk	39.63%	10.23%

Summary of Significant Accounting Policies (Details 3)	12 Months Ended
Summary of Significant Accounting Policies (Details 3)	Dec. 31, 2018	Dec. 31, 2017
Consolidated Balance Sheets
Gain loss on foreign currency transaction	RMB 6.8634 to $1.00	RMB 6.5359 to $1.00
Consolidated Statements of Operations and Comrpehensive Income
Gain loss on foreign currency transaction	RMB 6.6181 to $1.00	RMB 6.7522 to $1.00

Summary of Significant Accounting Policies (Details 4) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income (loss)	$ 6,574	$ (872)
Net income (loss) attributable to non-controlling interest	0	(554)
Net income (loss) available to common stockholders, basic and diluted	$ 6,574	$ (318)
Denominator:
Weighted average shares outstanding, basic	15,788,460	6,865,390
Effect of dilutive securities	2,123,645	0
Weighted average shares outstanding, diluted	17,912,105	6,865,390
Net income (loss) per common share:
Basic	$ 0.42	$ (0.05)
Diluted	$ 0.37	$ (0.05)

Summary of Significant Accounting Policies (Details 5) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Antidilutive securities	3,795,779	3,849,794
Stock Options
Antidilutive securities	3,715,779	3,372,292
Warrants
Antidilutive securities	80,000	477,502

Summary of Significant Accounting Policies (Details 6) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Liabilities:
Short-term borrowings	$ 9,447	$ 5,095
Warrant liability	0	3,079
Financial and Nonfinancial Liabilities, Fair Value Disclosure, Total	9,447	8,174
Fair Value, Inputs, Level 1 [Member]
Liabilities:
Short-term borrowings	0	0
Warrant liability	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure, Total	0	0
Fair Value, Inputs, Level 2 [Member]
Liabilities:
Short-term borrowings	9,447	5,095
Warrant liability	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure, Total	9,447	5,095
Fair Value, Inputs, Level 3 [Member]
Liabilities:
Short-term borrowings	0	0
Warrant liability	0	3,079
Financial and Nonfinancial Liabilities, Fair Value Disclosure, Total	$ 0	$ 3,079

Summary of Significant Accounting Policies (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Shipping and handling charged to Selling and marketing expenses	$ 146	$ 139
Other Shipping and handling charged to Selling and marketing expenses	$ 144	$ 135

Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Accounts receivable	$ 24,608	$ 26,762
Less: Allowance for doubtful accounts	0	0
Total	$ 24,608	$ 26,762

Accounts Receivable (Details Narrative) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Allowance for doubtful accounts	$ 0	$ 0
Accounts receivable were pledged as collateral for borrowings	$ 1,457	$ 1,805

Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 12,646	$ 6,181
Work in process	9,631	4,328
Finished goods	16,487	4,879
Total inventory, gross	38,764	15,388
Inventory reserve	0	0
Total inventory, net	$ 38,764	$ 15,388

Inventory (Details Narrative) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventory reserve	$ 0	$ 0

Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Total cost	$ 11,778	$ 10,603
Less: Total accumulated depreciation	(8,102)	(8,263)
Construction in progress	32	0
Total property, plant and equipment, net	3,708	2,340
Tools, Dies and Molds [Member]
Total cost	9,703	9,660
Total property, plant and equipment, net		9,660
Office Equipment [Member]
Total cost	512	463
Total property, plant and equipment, net		463
Transportation Equipment [Member]
Total cost	184	203
Total property, plant and equipment, net		203
Leasehold Improvements [Member]
Total cost	$ 1,379	277
Total property, plant and equipment, net		$ 277

Property, Plant and Equipment, Net (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment Capitalized Interest Costs [Abstract]
Depreciation expense	$ 350	$ 243

Short-Term Borrowing (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Short-term borrowings	$ 9,447	$ 5,095
Borrowings One
Short-term borrowings	0	2,219
Borrowings Two
Short-term borrowings	0	2,111
Borrowings Three
Short-term borrowings	3,133	0
Line of Credit One
Short-term borrowings	485	0
Line of Credit Two
Short-term borrowings	0	765
Line of Credit Three
Short-term borrowings	1,457	0
Line of Credit Four
Short-term borrowings	2,186	0
Line of Credit Five
Short-term borrowings	$ 2,186	$ 0

Short-Term Borrowings (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Interest expense related to short-term borrowings	$ 498	$ 272

Other Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Lease expenses and payable for leasehold improvement due to a related party (note 11)	$ 53	$ 2,024
Commissions	2,931	836
Accrued warranty	1,710	839	$ 290
Accrued payroll	626	745
Accrued professional fees	64	60
Accrued machine testing fee	3,076	684
Others	1,950	849
Total	$ 10,410	$ 6,037

Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other long-term liabilities	$ 4,583	$ 6,217
Subsidies to Stress Free Polishing project [Member]
Other long-term liabilities	1,483	1,952
Subsidies to Electro Copper Plating project [Member]
Other long-term liabilities	2,860	4,265
Subsidies to Polytetrafluoroethylene [Member]
Other long-term liabilities	178	0
Other [Member]
Other long-term liabilities	$ 62	$ 0

Equity Method Investment (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Post-closing equity purchase price	$ 0	$ 1,200
Ninebell [Member]
Undistributed earnings attributable to ACM's equity method investment	$ 123	$ 37

Related Party Balances and Transactions (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounts payable-related party	$ 1,477	$ 2,118
Operating Lease Agreement [Member] \| Shanghai Zhangjiang Group Co., Ltd. [Member]
Leasing expense under lease agreement	620	638
Lease expenses and payable for leasehold improvement due to a related party	$ 53	$ 2,024

Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
2019	$ 1,391
2020	1,371
2021	1,403
2022	1,441
Total	$ 5,606

Leases (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
Leases (Details Narrative) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Rent expense	$ 1,867	$ 670
Rent expense	$ 1,867	$ 670

Common Stock (Details Narrative) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Common Class A [Member]
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares issued	14,110,315	12,935,546
Common stock, shares outstanding	14,110,315	12,935,546
Common Class B [Member]
Common stock, shares authorized	7,303,533	7,303,533
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares issued	1,898,423	2,409,738
Common stock, shares outstanding	1,898,423	2,409,738

Stock-Based Compensation (Details) - $ / shares	12 Months Ended
Stock-Based Compensation (Details) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Employee Stock Option [Member]
Number of Option Shares, Outstanding, Beginning balance	2,045,616	2,100,377
Number of Option Shares, Outstanding, Granted	745,700	140,002
Number of Option Shares, Outstanding, Exercised	(151,650)	(174,334)
Number of Option Shares, Outstanding, Expired	(4,622)	(3,752)
Number of Option Shares, Outstanding, Forfeited	(131,639)	(16,677)
Number of Option Shares, Outstanding, Ending balance	2,503,405	2,045,616
Vested and exercisable	1,327,189
Weighted Average Grant Date Fair Value, Outstanding, Beginning balance	$ 0.66	$ 0.54
Weighted Average Grant Date Fair Value, Granted	1.52	2.28
Weighted Average Grant Date Fair Value, Exercised	0.53	0.45
Weighted Average Grant Date Fair Value, Expired	0.55	0.54
Weighted Average Grant Date Fair Value, Forfeited	0.97	0.54
Weighted Average Grant Date Fair Value, Outstanding, Ending balance	0.91	0.66
Weighted Average Exercise Price, Outstanding, Beginning balance	2.46	2.03
Weighted Average Exercise Price, Granted	8.12	6.75
Weighted Average Exercise Price, Exercised	2.06	0.75
Weighted Average Exercise Price, Expired	3.00	3.00
Weighted Average Exercise Price, Forfeited	3.87	3.00
Weighted Average Exercise Price, Outstanding, Ending balance	$ 4.09	$ 2.46
Weighted Average Remaining Contractual Term, Outstanding	7 years 3 months 18 days	7 years 6 months 25 days
Non Employee Awards [Member]
Number of Option Shares, Outstanding, Beginning balance	1,326,676	1,578,565
Number of Option Shares, Outstanding, Granted	0	196,669
Number of Option Shares, Outstanding, Exercised	(114,302)	(298,555)
Number of Option Shares, Outstanding, Expired	0	(133,336)
Number of Option Shares, Outstanding, Forfeited	0	(16,667)
Number of Option Shares, Outstanding, Ending balance	1,212,374	1,326,676
Vested and exercisable	946,691
Weighted Average Grant Date Fair Value, Outstanding, Beginning balance	$ 0.78	$ 0.51
Weighted Average Grant Date Fair Value, Granted	0.00	2.25
Weighted Average Grant Date Fair Value, Exercised	0.43	0.39
Weighted Average Grant Date Fair Value, Expired	0.00	0.45
Weighted Average Grant Date Fair Value, Forfeited	0.00	2.58
Weighted Average Grant Date Fair Value, Outstanding, Ending balance	0.78	0.78
Weighted Average Exercise Price, Outstanding, Beginning balance	2.52	1.58
Weighted Average Exercise Price, Granted	0.00	6.90
Weighted Average Exercise Price, Exercised	1.92	0.93
Weighted Average Exercise Price, Expired	0.00	0.75
Weighted Average Exercise Price, Forfeited	0.00	7.5
Weighted Average Exercise Price, Outstanding, Ending balance	$ 2.57	$ 2.52
Weighted Average Remaining Contractual Term, Outstanding	6 years 7 months 28 days	7 years 6 months 14 days

Stock-Based Compensation (Details 1) - $ / shares	12 Months Ended
Stock-Based Compensation (Details 1) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Employee Stock Option [Member]
Expected term in years	6 years 3 months	6 years 3 months
Expected dividend	0.00%	0.00%
Employee Stock Option [Member] \| Minimum [Member]
Fair value of common share	$ 5.31	$ 5.60
Volatility	39.14%	28.62%
Risk-free interest rate	2.55%	2.21%
Employee Stock Option [Member] \| Maximum [Member]
Fair value of common share	$ 13.85	$ 7.59
Volatility	43.00%	29.18%
Risk-free interest rate	2.96%	2.22%
Non Employee Awards [Member]
Fair value of common share	$ 10.88
Expected dividend		0.00%
Non Employee Awards [Member] \| Minimum [Member]
Fair value of common share		$ 5.25
Expected term in years	2 years 6 months 29 days	3 years 6 months 29 days
Volatility	40.24%	28.71%
Risk-free interest rate	2.39%	1.62%
Expected dividend	0.00%
Non Employee Awards [Member] \| Maximum [Member]
Fair value of common share		$ 7.59
Expected term in years	5 years 4 months 10 days	6 years 3 months
Volatility	45.48%	29.41%
Risk-free interest rate	2.94%	2.43%

Stock-Based Compensation (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Non Employee Awards [Member]
Stock-based compensation expense	$ 2,651	$ 1,351
Number of options granted	0	196,669
Employee Stock Option [Member]
Stock-based compensation expense	$ 712	$ 271
Unrecognized employee stock-based compensation expense, net of estimated forfeitures	$ 2,424	$ 729
Weighted-average period over which unrecognized compensation is expected to be recognized	1 year 7 months 13 days	1 year 9 months 7 days
Number of options granted	745,700	140,002

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current:
U.S. federal	$ 0	$ 0
U.S. state	0	0
Foreign	(1,149)	0
Total current tax expense	(1,149)	0
Deferred:
U.S. federal	0	0
U.S. state	0	0
Foreign	343	(547)
Total deferred tax expense	343	(547)
Total income tax expense	$ (806)	$ (547)

Income Taxes (Details 1) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carry forwards (offshore)	$ 16	$ 4,418
Net operating loss carry forwards (U.S.) and credit	4,105	683
Deferred revenue (offshore)	558	656
Accruals (U.S.)	11	18
Reserves and other (offshore)	1,080	495
Stock-based compensation (U.S.)	1,021	453
Property and equipment (U.S.)	1	2
Total gross deferred tax assets	6,792	6,725
Less: valuation allowance	(5,155)	(5,431)
Total deferred tax assets	1,637	1,294
Total deferred tax liabilities	0	0
Translation difference	0	0
Deferred tax assets, net	$ 1,637	$ 1,294

Income Taxes (Details 2)	12 Months Ended
Income Taxes (Details 2)	Dec. 31, 2018	Dec. 31, 2017
Effective tax rate reconciliation:
Income tax provision at statutory rate	21.00%	34.00%
State taxes, net of Federal benefit	0.00%	0.00%
Foreign rate differential	(20.88%)	6.80%
Other permanent difference	15.59%	197.70%
Effect of Tax Reform	0.00%	(757.00%)
Change in valuation allowance	(4.78%)	349.90%
Total income tax (expense) benefit	(10.93%)	(168.60%)

Income Taxes (Details 3) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details 3) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Taxes Details 3Abstract
Beginning balance	$ 44	$ 44
Increase/(Decrease) of unrecognized tax benefits taken in prior years	0	0
Increase/(Decrease) of unrecognized tax benefits related to current year	0	0
Increase/(Decreases) of unrecognized tax benefits related to settlements	0	0
Reductions to unrecognized tax benefits related to lapsing statute of limitations	0	0
Ending balance	$ 1,193	$ 44

Income Taxes (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details Narrative) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory U.S federal income tax rate	21.00%	34.00%
Statutory Chinese income tax rate	(20.88%)	6.80%
Income tax provision (benefit)	$ 806	$ 547
Unrecognized tax benefits	$ 44	$ 44

Commitments and Contingencies (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Rental expenses	$ 1,867	$ 670

Parent Company Only Condensed Financial Information (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 27,124	$ 17,681	$ 10,119
Accounts Receivable	24,608	26,762
Inventory	38,764	15,388
Total current assets	96,028	62,914
Total assets	103,047	67,891
Liabilities, Redeemable Convertible Preferred Stock and Stockholders’ Equity
Total liabilities	50,723	28,034
Total stockholders’ equity	52,324	39,857
Total liabilities, redeemable convertible preferred stock and stockholders’ equity	103,047	67,891
Parent
Current assets:
Cash and cash equivalents	13,161	10,874	$ 7,264
Accounts Receivable	983	118
Inventory	720	565
Due from intercompany	14,494	12,669
Other receivable	175	50
Total current assets	29,533	24,276
Investment in unconsolidated subsidiaries	26,861	15,476
Due from related party	0	946
Total assets	56,394	40,698
Liabilities, Redeemable Convertible Preferred Stock and Stockholders’ Equity
Notes payable	0	11
Accounts payable	2,818	739
Other payable	58	47
Income taxes payable	1,193	44
Total liabilities	4,069	841
Total redeemable convertible preferred stocks	0	0
Total stockholders’ equity	52,325	39,857
Total liabilities, redeemable convertible preferred stock and stockholders’ equity	$ 56,394	$ 40,698

Parent Company Only Condensed Financial Information (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 74,643	$ 36,506
Cost of revenue	40,194	19,281
Gross profit	34,449	17,225
Operating expenses:
General and administrative expenses	7,987	5,887
Research and development expenses	10,380	5,138
Other income (expense), net	1,255	(794)
Interest expense, net	498	277
Income (loss) before income taxes	7,380	(325)
Income tax expense (benefit)	806	547
Net income (loss)	6,574	(318)
Parent
Revenue	25,506	6,985
Cost of revenue	(23,927)	(6,394)
Gross profit	1,579	591
Operating expenses:
Sales and marketing expenses	(301)	(368)
General and administrative expenses	(5,083)	(3,961)
Research and development expenses	(255)	(50)
Loss from operations	(4,060)	(3,788)
Equity in earnings of unconsolidated subsidiaries	10,360	3,475
Other income (expense), net	108	0
Interest expense, net	166	(5)
Income (loss) before income taxes	6,574	(318)
Income tax expense (benefit)	0	0
Net income (loss)	$ 6,574	$ (318)

Parent Company Only Condensed Financial Information (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Net increase in cash and cash equivalents	$ 9,443	$ 7,562
Cash and cash equivalents at beginning of period	17,681	10,119
Effect of exchange rate changes on cash and cash equivalents	(518)	663
Cash and cash equivalents at end of period	27,124	17,681
Parent
Net cash used in operating activities	(1,189)	(13,848)
Net cash used in investing activities	946	(21,754)
Net cash provided by financing activities	3,510	38,676
Net increase in cash and cash equivalents	3,267	3,074
Cash and cash equivalents at beginning of period	10,874	7,264
Effect of exchange rate changes on cash and cash equivalents	(980)	536
Cash and cash equivalents at end of period	$ 13,161	$ 10,874