FormFactor (FORM) 10-Q 4 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 27, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 27, 2021
Document Transition Report	false
Entity File Number	000-50307
Entity Registrant Name	FormFactor, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3711155
Entity Address, Address Line One	7005 Southfront Road
Entity Address, City or Town	Livermore
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94551
City Area Code	925
Local Phone Number	290-4000
Title of 12(b) Security	Common stock, $0.001 par value
Trading Symbol	FORM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		77,622,717
Amendment Flag	false
Entity Central Index Key	0001039399
Current Fiscal Year End Date	--12-25
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Current assets:
Cash and cash equivalents	$ 173,616	$ 187,225
Marketable securities	94,093	67,810
Accounts receivable, net of allowance for doubtful accounts of $232 and $248	103,500	107,603
Inventories, net	104,727	99,229
Restricted cash	2,798	1,904
Prepaid expenses and other current assets	19,371	23,303
Total current assets	498,105	487,074
Restricted cash	1,894	1,969
Operating lease, right-of-use-assets	37,208	30,756
Property, plant and equipment, net of accumulated depreciation	112,312	104,103
Goodwill	214,218	212,761
Intangibles, net	48,786	59,147
Deferred tax assets	65,821	66,242
Other assets	1,867	1,165
Total assets	980,211	963,217
Current liabilities:
Accounts payable	67,720	62,045
Accrued liabilities	43,468	55,342
Current portion of term loans, net of unamortized issuance costs	9,260	9,516
Deferred revenue	18,644	20,964
Operating lease liabilities	7,557	6,704
Total current liabilities	146,649	154,571
Term loans, less current portion, net of unamortized issuance costs	22,390	24,978
Deferred tax liabilities	4,965	5,346
Long-term operating lease liabilities	33,485	27,996
Other liabilities	6,189	6,242
Total liabilities	213,678	219,133
Stockholders’ equity:
Common stock, $0.001 par value	78	78
Treasury stock, at cost, 136,402 and — shares	(5,738)	0
Additional paid-in capital	915,136	903,838
Accumulated other comprehensive income	3,150	5,886
Accumulated deficit	(146,093)	(165,718)
Total stockholders’ equity	766,533	744,084
Total liabilities and stockholders’ equity	$ 980,211	$ 963,217
Common stock, shares outstanding (in shares)	77,758,530	77,437,997

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 232	$ 248
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	77,758,530	77,437,997
Common stock, shares outstanding (in shares)	77,758,530	77,437,997
Treasury stock (in shares)	136,402	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Income Statement [Abstract]
Revenues	$ 186,636	$ 160,753
Cost of revenues	109,930	93,363
Gross profit	76,706	67,390
Operating expenses:
Research and development	24,046	21,267
Selling, general and administrative	30,015	27,693
Total operating expenses	54,061	48,960
Operating income	22,645	18,430
Interest income	194	685
Interest expense	(180)	(318)
Other income (expense), net	172	(91)
Income before income taxes	22,831	18,706
Provision for income taxes	3,206	2,816
Net income	$ 19,625	$ 15,890
Net income per share:
Basic (In dollars per share)	$ 0.25	$ 0.21
Diluted (In dollars per share)	$ 0.25	$ 0.20
Weighted-average number of shares used in per share calculations:
Basic (in shares)	77,598	76,005
Diluted (in shares)	79,988	78,510

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 19,625	$ 15,890
Other comprehensive loss, net of tax:
Translation adjustments and other	(2,379)	(399)
Unrealized losses on available-for-sale marketable securities	(131)	(27)
Unrealized gains (losses) on derivative instruments	(226)	176
Other comprehensive loss, net of tax	(2,736)	(250)
Comprehensive income	$ 16,889	$ 15,640

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 28, 2019		75,764,990	0
Beginning balance at Dec. 28, 2019	$ 640,997	$ 76	$ 0	$ 885,821	$ (659)	$ (244,241)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under the Employee Stock Purchase Plan (in shares)		311,591
Issuance of common stock under the Employee Stock Purchase Plan	4,066			4,066
Issuance of common stock pursuant to exercise of options (in shares)		55,769
Issuance of common stock pursuant to exercise of options	447	$ 1		446
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		25,901
Issuance of common stock pursuant to exercise of options	(385)	$ 0		(385)
Stock-based compensation	5,652			5,652
Other comprehensive loss	(250)				(250)
Net income	15,890					15,890
Ending balance (in shares) at Mar. 28, 2020		76,158,251	0
Ending balance at Mar. 28, 2020	666,417	$ 77	$ 0	895,600	(909)	(228,351)
Beginning balance (in shares) at Dec. 26, 2020		77,437,997	0
Beginning balance at Dec. 26, 2020	744,084	$ 78	$ 0	903,838	5,886	(165,718)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under the Employee Stock Purchase Plan (in shares)		228,784
Issuance of common stock under the Employee Stock Purchase Plan	5,065			5,065
Issuance of common stock pursuant to exercise of options (in shares)		50,000
Issuance of common stock pursuant to exercise of options	422	$ 0		422
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		41,749
Issuance of common stock pursuant to exercise of options	(1,141)	$ 0		(1,141)
Purchase of common stock through repurchase program (in shares)			(136,402)
Purchase of common stock through repurchase program	(5,738)		$ (5,738)
Stock-based compensation	6,952			6,952
Other comprehensive loss	(2,736)				(2,736)
Net income	19,625					19,625
Ending balance (in shares) at Mar. 27, 2021		77,758,530	(136,402)
Ending balance at Mar. 27, 2021	$ 766,533	$ 78	$ (5,738)	$ 915,136	$ 3,150	$ (146,093)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Cash flows from operating activities:
Net income	$ 19,625	$ 15,890
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	6,130	4,561
Amortization	6,805	7,263
Reduction in the carrying amount of right-of-use assets	1,811	1,511
Stock-based compensation expense	7,077	5,623
Provision for excess and obsolete inventories	3,394	3,287
Other adjustments to reconcile net income to net cash provided by operating activities	2,140	407
Changes in assets and liabilities:
Accounts receivable	3,576	7,803
Inventories	(9,911)	928
Prepaid expenses and other current assets	3,011	(240)
Other assets	(50)	194
Accounts payable	5,722	763
Accrued liabilities	(12,732)	(6,970)
Other liabilities	114	33
Deferred revenues	(2,411)	(123)
Operating lease liabilities	(1,945)	(1,591)
Net cash provided by operating activities	32,356	39,339
Cash flows from investing activities:
Acquisition of property, plant and equipment	(13,470)	(12,050)
Proceeds from sale of a subsidiary	0	40
Purchases of marketable securities	(41,062)	(16,441)
Proceeds from maturities and sales of marketable securities	14,610	23,009
Net cash used in investing activities	(39,922)	(5,442)
Cash flows from financing activities:
Proceeds from issuances of common stock	5,487	4,513
Purchase of common stock through stock repurchase program	(5,738)	0
Tax withholdings related to net share settlements of equity awards	(1,141)	(385)
Principal repayments on term loans	(2,376)	(13,199)
Net cash used in financing activities	(3,768)	(9,071)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(1,456)	312
Net increase (decrease) in cash, cash equivalents and restricted cash	(12,790)	25,138
Cash, cash equivalents and restricted cash, beginning of period	191,098	147,937
Cash, cash equivalents and restricted cash, end of period	178,308	173,075
Non-cash investing and financing activities:
Change in accounts payable and accrued liabilities related to property, plant and equipment purchases	1,087	(2,116)
Operating lease, right-of-use assets obtained in exchange for lease obligations	8,572	6,307
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net	1,034	2,419
Cash paid for interest	173	291
Reconciliation of cash, cash equivalents and restricted cash:
Total cash, cash equivalents and restricted cash	$ 178,308	$ 173,075

Basis of Presentation and New A

Basis of Presentation and New Accounting Pronouncements	3 Months Ended
	Mar. 27, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and New Accounting Pronouncements	Basis of Presentation and New Accounting Pronouncements Basis of Presentation The accompanying condensed consolidated financial information of FormFactor, Inc. is unaudited and has been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). However, such information reflects all adjustments, consisting only of normal recurring adjustments, which are, in the opinion of management, necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods. The condensed consolidated financial statements included herein should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2020 Annual Report on Form 10-K filed with the SEC on February 22, 2021. The results of operations for the interim periods presented are not necessarily indicative of the results to be expected for the full year. Fiscal Year We operate on a 52/53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2021 and 2020 each contain 52 weeks and the three months ended March 27, 2021 and March 28, 2020 each contained 13 weeks. Fiscal 2021 will end on December 25, 2021. Significant Accounting Policies Our significant accounting policies have not changed during the three months ended March 27, 2021 from those disclosed in our Annual Report on Form 10-K for the year ended December 26, 2020. Reclassifications Certain immaterial reclassifications were made to the prior year financial statements to conform to the current year presentation. New Accounting Pronouncements ASU 2019-12 In December 2019, the Financial Accounting Standard Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, “Income Taxes (Topic 740),” which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU 2019-12 on a prospective basis on December 27, 2020, the first day of fiscal 2021. The adoption did not have a material effect on our consolidated financial position, results of operations or cash flows. ASU 2020-04 In March 2020, the FASB issued ASU 2020-04, “Referenced Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The ASU provides temporary optional expedients and exceptions for applying generally accepted accounting principles to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. In January 2021, the FASB issued ASU 2021-01, “Reference Rate Reform (Topic 848),” which permits entities to apply optional expedients in Topic 848 to derivative instruments modified because of discounting transition resulting from reference rate reform. ASU 2020-04 became effective upon issuance and may be applied prospectively to contract modifications made on or before December 31, 2022. ASU 2021-01 became effective upon issuance and may be applied on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020 or prospectively for contract modifications made on or before December 31, 2022. The Company has not yet applied the relief afforded by these standard amendments and is currently assessing contracts that will require modification due to reference rate reform to which these standard amendments may be applied.

Concentration of Credit and Oth

Concentration of Credit and Other Risks	3 Months Ended
	Mar. 27, 2021
Risks and Uncertainties [Abstract]
Concentration of Credit and Other Risks	Concentration of Credit and Other Risks Each of the following customers accounted for 10% or more of our revenues for the periods indicated: Three Months Ended March 27, March 28, Intel Corporation 28.1 % 36.2 % Taiwan Semiconductor Manufacturing Co., LTD. 11.5 % * 39.6 % 36.2 % *Represents less than 10% of total revenues.

Inventories, net

Inventories, net	3 Months Ended
	Mar. 27, 2021
Inventory Disclosure [Abstract]
Inventories, net	Inventories, net Inventories are stated at the lower of cost (principally standard cost, which approximates actual cost on a first in, first out basis) or net realizable value. Inventories, net, consisted of the following (in thousands): March 27, December 26, Raw materials $ 52,320 $ 48,122 Work-in-progress 35,466 30,806 Finished goods 16,941 20,301 $ 104,727 $ 99,229

Acquisition

Acquisition	3 Months Ended
	Mar. 27, 2021
Business Combinations [Abstract]
Acquisition	Acquisition High Precision Devices, Inc. Acquisition On October 19, 2020, we acquired 100% of the shares of HPD for total consideration of $16.9 million, net of cash acquired of $1.7 million, which included an estimated adjustment for changes in working capital, which is not yet finalized. This acquisition brings highly specialized skills and know-how to address the unique test challenges within the emerging quantum computing, superconducting computing, and ultra-sensitive sensor markets which operate at temperatures as low as 30 millikelvin. The acquisition was accounted for using the acquisition method of accounting, with FormFactor treated as the acquirer. The acquired assets and liabilities of HPD were recorded at their respective fair values including an amount for goodwill representing the difference between the acquisition consideration and the fair value of the identifiable net assets. Our Condensed Consolidated Statements of Income include the financial results of HPD subsequent to the acquisition date of October 19, 2020. Revenue in fiscal 2020 related to HPD subsequent to the acquisition date that was included in our Condensed Consolidated Statements of Income was not material. The acquisition price was allocated to the tangible and identified intangible assets acquired and liabilities assumed as of the closing date of the acquisition based upon their respective fair values. The fair values assigned to assets acquired and liabilities assumed were based on management’s assumptions as of the reporting date. We estimated the acquisition price and the allocation of fair value to assets acquired and liabilities assumed as of the acquisition date, October 19, 2020. We subsequently made certain immaterial adjustments within the measurement period to the preliminary acquisition price allocation. See Note 5, Goodwill and Intangible Assets , for changes in identified intangible values and goodwill. Our purchase accounting remains open at March 27, 2021, subject to finalization of the fair value of consideration and certain deferred tax items. The estimated fair value of assets acquired, including goodwill and intangibles, and liabilities assumed is as follows (in thousands): Amount Cash and cash equivalents $ 1,680 Accounts receivable 1,017 Inventory 3,047 Property, plant and equipment 669 Operating lease, right of use assets 2,554 Prepaid expenses and other current assets 599 Tangible assets acquired 9,566 Deferred revenue (2,529) Accounts payable and accrued liabilities (1,268) Operating lease liabilities (2,554) Deferred tax liabilities (2,840) Total tangible assets acquired and liabilities assumed 375 Intangible assets 11,520 Goodwill 6,665 Net Assets Acquired $ 18,560 The intangible assets as of the closing date of the acquisition included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 7,500 10.0 Customer relationships 3,600 5.0 Order backlog 200 0.5 Trade names 220 5.0 Total intangible assets $ 11,520 8.2 The fair value of the intangible assets acquired in connection with the acquisition was determined using either the income, market or replacement cost methodologies. The intangible assets are being amortized over periods which reflect the pattern in which economic benefits of the assets are expected to be realized. Identifiable Intangible Assets Valuation of intangible assets involves multiple assumptions. The key assumptions are described below. Developed technology acquired primarily consists of existing technology related to cryogenic probe stations, Adiabatic Demagnetization Refrigerator (“ADR”), and continuous ADR cryostats and similar tools, and technology related to other cryogenic applications. We valued the developed technology using the multi-period excess earnings method under the income approach. Using this approach, the estimated fair values were calculated using expected future cash flows from specific products discounted to their net present values at an appropriate risk-adjusted rate of return. The value of customer relationships represents the fair value of future projected revenues that will be derived from the sale of products to HPD's existing customers. We valued customer relationships using the incremental cash flow method. This method estimates value based on the incremental cash flow afforded by having the customers relationships in place on the acquisition date versus having no relationships in place and needing to replicate or replace those relationships. The incremental cash flows are then discounted to a present value to arrive at an estimate of fair value for this asset class. Order backlog represents the value of future sales under existing contracts as of the acquisition date. Expected cash flow from order backlog was valued on a discounted direct cash flow basis, net of returns on contributory assets such as working capital, property and equipment, trade name and assembled workforce. The identified trade names intangibles relate to the estimated fair value of future cash flows related to the HPD brand. We valued trade names by applying the relief-from-royalty method under the income approach. This method is based on the application of a royalty rate to forecasted revenue under the trade name. Goodwill The excess of purchase price over the fair value assigned to the assets acquired and liabilities assumed represents the amount of goodwill resulting from the acquisition. We believe the factors that contributed to goodwill include synergies that are specific to our consolidated business, such as cost savings and operational efficiencies, and the acquisition of a talented workforce that expands our expertise in business development and commercializing semiconductor test products, none of which qualify for recognition as a separate intangible asset. We do not expect any portion of this goodwill to be deductible for tax purposes. The goodwill attributable to the acquisition was recorded as a non-current asset and is not amortized, but is subject to an annual review for impairment. The goodwill arising from the acquisition was allocated to the HPD reporting unit within the Systems reportable segment. We have not presented unaudited combined pro forma financial information as the HPD acquisition was not significant to our consolidated results of operations and financial position. Baldwin Park Acquisition On July 30, 2020, we acquired the probe card assets of Advantest Corporation for total cash consideration of $35.0 million. This acquisition brings important enabling technologies and capabilities for designing and manufacturing advanced probe cards, and adds a complementary 3D-NAND Flash probe-card product that is qualified and in production at one of the world's leading NAND Flash manufacturers. The acquisition was accounted for using the acquisition method of accounting, with FormFactor treated as the acquirer. The acquired assets and liabilities of Baldwin Park were recorded at their respective fair values including an amount for goodwill representing the difference between the acquisition consideration and the fair value of the identifiable net assets. Our Condensed Consolidated Statements of Income include the financial results of Baldwin Park subsequent to the acquisition date of July 30, 2020. Revenue related to Baldwin Park since the acquisition date that was included in our Condensed Consolidated Statements of Income for fiscal 2020 was not material. We estimated the acquisition price and the allocation of fair value to assets acquired and liabilities assumed as of the acquisition date, July 30, 2020. We subsequently made certain immaterial adjustments within the measurement period to the acquisition price allocation as a result of finalization of our valuation of identifiable assets and liabilities. See Note 5, Goodwill and Intangible Assets, for changes in identified intangible values and goodwill. In the current quarter ended March 27, 2021, we finalized our allocation of the assets acquired, including goodwill and intangibles, and liabilities assumed for the purchase as follows (in thousands): Amount Accounts receivable $ 4,365 Inventory 2,727 Property, plant and equipment 9,053 Operating lease, right of use assets 519 Prepaid expenses and other current assets 56 Tangible assets acquired 16,720 Accounts payable and accrued liabilities (743) Operating lease liabilities (519) Total net tangible assets acquired and liabilities assumed 15,458 Intangible assets 13,600 Goodwill 5,942 Net assets acquired $ 35,000 The intangible assets as of July 30, 2020 included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 8,800 10.0 Customer relationships 4,400 3.0 In-process research and development 400 N/A Total intangible assets $ 13,600 7.7 Indications of fair value of the intangible assets acquired in connection with the acquisition were determined using either the income, market or replacement cost methodologies. The intangible assets are being amortized over periods which reflect the pattern in which economic benefits of the assets are expected to be realized. Identifiable Intangible Assets Valuation of intangible assets involves multiple assumptions. The key assumptions are described below. Developed technology acquired consists of existing technology related to 3D NAND Flash probe cards and the value expected to be derived from interconnect technology. We valued the developed technology related to 3D NAND Flash using the multi-period excess earnings method under the income approach. Using this approach, the estimated fair values were calculated using expected future cash flows from specific products discounted to their net present values at an appropriate risk-adjusted rate of return. We valued the interconnect developed technology asset using the incremental cash flow method. This method estimates value based on the incremental cash flow afforded by having the interconnect capability in place on the acquisition date versus having no capability in place and needing to replicate or replace that capability. The incremental cash flows are then discounted to a present value to arrive at an estimate of fair value for this asset class. In-process research and development (“IPR&D”) acquired primarily consists of research and development projects that were in process at the time of acquisition related to technologies used in DRAM probe cards. Once these projects are complete they will be amortized over their useful life. We valued the IPR&D using the multi-period excess earnings method under the income approach. Using this approach, the estimated fair values were calculated using expected future cash flows from specific products discounted to their net present values at an appropriate risk-adjusted rate of return. The value of customer relationships represents the fair value of future projected revenues that will be derived from the sale of products to Baldwin Park's existing customers. We valued customer relationships using the incremental cash flow method. This method estimates value based on the incremental cash flow afforded by having the customers relationships in place on the acquisition date versus having no relationships in place and needing to replicate or replace those relationships. The incremental cash flows are then discounted to a present value to arrive at an estimate of fair value for this asset class. Goodwill The excess of purchase price over the fair value assigned to the assets acquired and liabilities assumed represents the amount of goodwill resulting from the acquisition. We believe the factors that contributed to goodwill include synergies that are specific to our consolidated business, such as cost savings and operational efficiencies, and the acquisition of a talented workforce that expands our expertise in business development, none of which qualify for recognition as a separate intangible asset. We expect this goodwill to be deductible for tax purposes. The goodwill attributable to the acquisition was recorded as a non-current asset and is not amortized, but is subject to an annual review for impairment. The goodwill arising from the acquisition was allocated to the Probe Cards reporting unit within the Probe Cards reportable segment. We have not presented unaudited combined pro forma financial information as the Baldwin Park acquisition was not significant to our consolidated results of operations and financial position.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 27, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill by reportable segment was as follows (in thousands): Probe Cards Systems Total Goodwill, gross, as of December 28, 2019 $ 172,482 $ 26,714 $ 199,196 Addition - FRT GmbH Acquisition — 975 975 Addition - Baldwin Park Acquisition 5,590 — 5,590 Addition - HPD Acquisition — 4,654 4,654 Foreign currency translation — 2,346 2,346 Goodwill, gross, as of December 26, 2020 178,072 34,689 212,761 Addition - Baldwin Park Acquisition 352 352 Addition - HPD Acquisition — 2,011 2,011 Foreign currency translation — (906) (906) Goodwill, gross, as of March 27, 2021 $ 178,424 $ 35,794 $ 214,218 We have not recorded goodwill impairments for the three months ended March 27, 2021. Intangible assets were as follows (in thousands): March 27, 2021 December 26, 2020 Intangible Assets Gross Accumulated Net Gross Accumulated Net Developed technologies $ 173,318 $ 142,344 $ 30,974 $ 176,265 $ 137,754 $ 38,511 Trade names 8,100 7,418 682 8,162 7,363 799 Customer relationships 51,557 34,899 16,658 52,488 33,378 19,110 Backlog 1,969 1,897 72 2,227 1,900 327 In-process research and development 400 — 400 400 — 400 $ 235,344 $ 186,558 $ 48,786 $ 239,542 $ 180,395 $ 59,147 Amortization expense was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended March 27, March 28, Cost of revenues $ 5,090 $ 5,750 Selling, general and administrative 1,715 1,513 $ 6,805 $ 7,263 The estimated future amortization of definite-lived intangible assets, excluding in-process research and development, is as follows (in thousands): Fiscal Year Amount Remainder of 2021 $ 11,933 2022 9,591 2023 7,240 2024 4,625 2025 4,364 Thereafter 10,633 $ 48,386

Accrued Liabilities

Accrued Liabilities	3 Months Ended
	Mar. 27, 2021
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consisted of the following (in thousands): March 27, December 26, Accrued compensation and benefits $ 28,092 $ 33,110 Accrued income and other taxes 3,008 6,976 Accrued warranty 3,719 3,918 Employee stock purchase plan contributions withheld 2,109 4,240 Accrued contingent consideration 3,884 4,012 Other accrued expenses 2,656 3,086 $ 43,468 $ 55,342

Fair Value and Derivative Instr

Fair Value and Derivative Instruments	3 Months Ended
	Mar. 27, 2021
Fair Value Disclosures [Abstract]
Fair Value and Derivative Instruments	Fair Value and Derivative Instruments Whenever possible, the fair values of our financial assets and liabilities are determined using quoted market prices of identical securities or quoted market prices of similar securities from active markets. The three levels of inputs that may be used to measure fair value are as follows: • Level 1 valuations are obtained from real-time quotes for transactions in active exchange markets involving identical securities; • Level 2 valuations utilize significant observable inputs, such as quoted prices for similar assets or liabilities, quoted prices near the reporting date in markets that are less active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and • Level 3 valuations utilize unobservable inputs to the valuation methodology and include our own data about assumptions market participants would use in pricing the asset or liability based on the best information available under the circumstances. We did not have any transfers of assets or liabilities measured at fair value on a recurring basis to or from Level 1, Level 2 or Level 3 during the three months ended March 27, 2021 or the year ended December 26, 2020. The carrying values of Cash, Accounts receivable, net, Restricted cash, Prepaid expenses and other current assets, Accounts payable, Accrued liabilities, and term loans, net of unamortized issuance costs, approximate fair value due to their short maturities. No changes were made to our valuation techniques during the first three months of fiscal 2021. Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets and liabilities measured at fair value on a recurring basis were as follows (in thousands): March 27, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 34,254 $ — $ — $ 34,254 Commercial paper 5,500 — — 5,500 39,754 — — 39,754 Marketable securities: U.S. treasuries 32,669 — — 32,669 Certificates of deposit — 1,212 — 1,212 U.S. agency securities — 575 — 575 Corporate bonds — 44,146 — 44,146 Commercial paper — 15,491 — 15,491 32,669 61,424 — 94,093 Foreign exchange derivative contracts (Designated) — 144 — 144 Interest rate swap derivative contracts — 745 — 745 Total assets $ 72,423 $ 62,313 $ — $ 134,736 Liabilities: Foreign exchange derivative contracts (Designated) $ — $ (100) $ — $ (100) Interest rate swap derivative contracts — (113) — (113) Contingent consideration — — (3,884) (3,884) Total liabilities $ — $ (213) $ (3,884) $ (4,097) December 26, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 43,019 $ — $ — $ 43,019 Marketable securities: U.S. treasuries 40,726 — — 40,726 Certificates of deposit — 2,179 — 2,179 U.S. agency securities — 575 — 575 Corporate bonds — 24,330 — 24,330 40,726 27,084 — 67,810 Foreign exchange derivative contracts — 1,057 — 1,057 Interest rate swap derivative contracts — 57 — 57 Total assets $ 83,745 $ 28,198 $ — $ 111,943 Liabilities: Interest rate swap derivative contracts $ — $ (87) $ — $ (87) Contingent consideration — — (4,012) (4,012) Total liabilities $ — $ (87) $ (4,012) $ (4,099) Cash Equivalents The fair value of our cash equivalents is determined based on quoted market prices for similar or identical securities. Marketable Securities We classify our marketable securities as available-for-sale and value them utilizing a market approach. Our investments are priced by pricing vendors who provide observable inputs for their pricing without applying significant judgment. Broker pricing is used mainly when a quoted price is not available, the investment is not priced by our pricing vendors or when a broker price is more reflective of fair value. Our broker-priced investments are categorized as Level 2 investments because fair value is based on similar assets without applying significant judgments. In addition, all investments have a sufficient trading volume to demonstrate that the fair value is appropriate. Unrealized gains and losses were immaterial and were recorded as a component of Accumulated other comprehensive income in our Condensed Consolidated Balance Sheets. We did not have any other-than-temporary unrealized gains or losses at either period end included in these financial statements. Contingent Consideration Contingent consideration, arising from the acquisition of FRT, is a cash amount equal to 1.5x EBIT as defined in the purchase agreement, up to a maximum of €10.3 million, payable subject to the performance of the acquired business in calendar 2020. We estimated the fair value of contingent consideration using a probability weighted approach. Key assumptions in determining the fair value of contingent consideration included estimating EBIT levels that we believed as of the acquisition date were likely to be achieved during the performance period and discounting at an appropriate discount rate. Contingent consideration as of March 27, 2021 was estimated to be $3.9 million, with the change from December 26, 2020 resulting from foreign currency translation. Interest Rate Swaps The fair value of our interest rate swap contracts is determined at the end of each reporting period based on valuation models that use interest rate yield curves as inputs. For accounting purposes, our interest rate swap contracts qualify for, and are designated as, cash flow hedges. The cash flows associated with the interest rate swaps are reported in Net cash provided by operating activities in our Condensed Consolidated Statements of Cash Flows and the fair value of the interest rate swap contracts are recorded within Accrued liabilities and Other liabilities in our Condensed Consolidated Balance Sheets. The impact of the interest rate swaps on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Three Months Ended March 27, 2021 $ 624 Interest expense $ (38) Interest expense $ — Three Months Ended March 28, 2020 $ (96) Interest expense $ 22 Interest expense $ — Foreign Exchange Derivative Contracts We operate and sell our products in various global markets. As a result, we are exposed to changes in foreign currency exchange rates. We utilize foreign currency forward contracts to hedge against future movements in foreign exchange rates that affect certain existing foreign currency denominated assets and liabilities and forecasted foreign currency revenue and expense transactions. Under this program, our strategy is to have increases or decreases in our foreign currency exposures mitigated by gains or losses on the foreign currency forward contracts in order to mitigate the risks and volatility associated with foreign currency transaction gains or losses. We do not use derivative financial instruments for speculative or trading purposes. For accounting purposes, certain of our foreign currency forward contracts are not designated as hedging instruments and, accordingly, we record the fair value of these contracts as of the end of our reporting period in our Condensed Consolidated Balance Sheets with changes in fair value recorded within Other income (expense), net in our Condensed Consolidated Statement of Income for both realized and unrealized gains and losses. Certain of our foreign currency forward contracts are designated as cash flow hedges, and, accordingly, we record the fair value of these contracts as of the end of our reporting period in our Condensed Consolidated Balance Sheets with changes in fair value recorded as a component of Accumulated other comprehensive income and reclassified into earnings in the same period in which the hedged transaction affects earnings, and in the same line item on the Condensed Consolidated Statements of Income as the impact of the hedge transaction. The fair value of our foreign exchange derivative contracts was determined based on current foreign currency exchange rates and forward points. All of our foreign exchange derivative contracts outstanding at March 27, 2021 will mature by the first quarter of fiscal 2022. The following table provides information about our foreign currency forward contracts outstanding as of March 27, 2021 (in thousands): Currency Contract Position Contract Amount Contract Amount Euro Dollar Buy (10,141) $ (12,025) Euro Dollar Sell 11,043 13,026 Japanese Yen Buy (1,971,765) (17,977) Korean Won Sell 3,129,743 2,767 Taiwan Dollar Sell 7,972 279 Total USD notional amount of outstanding foreign exchange contracts $ (13,930) Our foreign currency contracts are classified within Level 2 of the fair value hierarchy as they are valued using pricing models that utilize observable market inputs. The impact of foreign exchange derivative contracts not designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized on Derivatives Three Months Ended Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized on Derivatives March 27, March 28, Foreign exchange forward contracts Other income (expense), net $ 1,288 $ (115) The impact of foreign exchange derivative contracts designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized in Accumulated OCI on Derivative Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Three Months Ended March 27, 2021 $ (526) Cost of revenues $ 250 Research and development 30 Selling, general and administrative 82 $ 362 Three Months Ended March 28, 2020 $ (3) Cost of revenues $ (120) Research and development (18) Selling, general and administrative (43) $ (181) Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis We measure and report our non-financial assets such as Property, plant and equipment, Goodwill and Intangible assets at fair value on a non-recurring basis if we determine these assets to be impaired or in the period when we make a business acquisition. Other than as discussed in Note 4, Acquisition

Warranty

Warranty	3 Months Ended
	Mar. 27, 2021
Product Warranties Disclosures [Abstract]
Warranty	Warranty We offer warranties on certain products and record a liability for the estimated future costs associated with warranty claims at the time revenue is recognized. The warranty liability is based upon historical experience and our estimate of the level of future costs. While we engage in product quality programs and processes, our warranty obligation is affected by product failure rates, material usage and service delivery costs. We continuously monitor product returns for warranty and maintain a reserve for the related expenses based upon our historical experience and any specifically identified failures. As we sell new products to our customers, we must exercise considerable judgment in estimating the expected failure rates. This estimating process is based on historical experience of similar products, as well as various other assumptions that we believe to be reasonable under the circumstances. We provide for the estimated cost of product warranties at the time revenue is recognized as a component of Cost of revenues in our Condensed Consolidated Statement of Income. Changes in our warranty liability were as follows (in thousands): Three Months Ended March 27, March 28, Balance at beginning of period $ 3,918 $ 1,942 Accruals 1,374 660 Settlements (1,573) (684) Balance at end of period $ 3,719 $ 1,918

Property, Plant, and Equipment,

Property, Plant, and Equipment, net	3 Months Ended
	Mar. 27, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	Property, Plant and Equipment, net Property, plant and equipment, net consisted of the following (in thousands): March 27, December 26, Land $ 4,751 $ 4,751 Machinery and equipment 233,357 226,185 Computer equipment and software 43,839 36,361 Furniture and fixtures 6,925 6,894 Leasehold improvements 80,011 79,144 Sub-total 368,883 353,335 Less: Accumulated depreciation and amortization (298,865) (294,468) Net, property, plant and equipment 70,018 58,867 Construction-in-process 42,294 45,236 Total $ 112,312 $ 104,103

Stockholders_ Equity and Stock-

Stockholders’ Equity and Stock-Based Compensation	3 Months Ended
	Mar. 27, 2021
Equity [Abstract]
Stockholders’ Equity and Stock-Based Compensation	Stockholders’ Equity and Stock-Based Compensation Common Stock Repurchase Program On October 26, 2020, our Board of Directors authorized a program to repurchase up to $50 million of outstanding common stock to offset potential dilution from issuances of common stock under our stock-based compensation plans. The share repurchase program will expire on October 28, 2022. During the three months ended March 27, 2021, we repurchased 136,402 shares of common stock for $5.7 million and, as of March 27, 2021, $44.3 million remained available for future repurchases. Our policy related to repurchases of our common stock is to charge the excess of cost over par value to additional paid-in capital once the shares are retired. All repurchases were made in compliance with Rule 10b-18 under the Securities Exchange Act of 1934, as amended. Restricted Stock Units Restricted stock unit (“RSU”) activity under our equity incentive plan was as follows: Units Weighted Average Grant Date Fair Value RSUs at December 26, 2020 2,840,922 $ 19.80 Awards granted 8,765 46.25 Awards vested (67,635) 16.38 Awards forfeited (11,140) 21.21 RSUs at March 27, 2021 2,770,912 19.96 Performance Restricted Stock Units We may grant Performance RSUs (“PRSUs”) to certain executives, which vest based upon us achieving certain market performance criteria. There were no PRSUs granted during the three months ended March 27, 2021. PRSUs are included as part of the RSU activity above. Stock Options Stock option activity under our equity incentive plan was as follows: Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Aggregate Intrinsic Value Outstanding at December 26, 2020 106,000 $ 8.35 Options exercised (50,000) 8.44 Outstanding at March 27, 2021 56,000 $ 8.28 0.92 $ 2,078,820 Vested and expected to vest at March 27, 2021 56,000 $ 8.28 0.92 $ 2,078,820 Exercisable at March 27, 2021 56,000 $ 8.28 0.92 $ 2,078,820 Employee Stock Purchase Plan Information related to activity under our Employee Stock Purchase Plan (“ESPP”) was as follows: Three Months Ended March 27, 2021 Shares issued 228,784 Weighted average per share purchase price $ 22.14 Weighted average per share discount from the fair value of our common stock on the date of issuance $ (18.73) Stock-Based Compensation Stock-based compensation was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended March 27, March 28, Cost of revenues $ 1,335 $ 937 Research and development 1,689 1,439 Selling, general and administrative 4,053 3,247 Total stock-based compensation $ 7,077 $ 5,623 Unrecognized Compensation Costs At March 27, 2021, the unrecognized stock-based compensation was as follows (dollars in thousands): Unrecognized Expense Average Expected Recognition Period in Years Restricted stock units $ 27,429 2.03 Performance restricted stock units 7,719 1.93 Employee stock purchase plan 973 0.86 Total unrecognized stock-based compensation expense $ 36,121 1.99

Net Income per Share

Net Income per Share	3 Months Ended
	Mar. 27, 2021
Earnings Per Share [Abstract]
Net Income per Share	Net Income per Share The following table reconciles the shares used in calculating basic net income per share and diluted net income per share (in thousands): Three Months Ended March 27, March 28, Weighted-average shares used in computing basic net income per share 77,598 76,005 Add potentially dilutive securities 2,390 2,505 Weighted-average shares used in computing diluted net income per share 79,988 78,510 Securities not included as they would have been antidilutive 3 9

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 27, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases See Note 13, Leases . Contractual Obligations and Commitments Our contractual obligations and commitments have not materially changed as of March 27, 2021 from those disclosed in our Annual Report on Form 10-K for the year ended December 26, 2020. Legal Matters

Leases

Leases	3 Months Ended
	Mar. 27, 2021
Leases [Abstract]
Leases	LeasesWe lease real estate space under non-cancelable operating lease agreements for commercial and industrial space, as well as for our corporate headquarters located in Livermore, California. Our leases have remaining terms of 1 to 8 years, and some leases include options to extend up to 20 years. We also have operating leases for automobiles with remaining lease terms of 1 to 4 years. We did not include any of our renewal options in our lease terms for calculating our lease liability as the renewal options allow us to maintain operational flexibility and we are not reasonably certain we will exercise these options at this time. The weighted-average remaining lease term for our operating leases was 6 years as of March 27, 2021 and the weighted-average discount rate was 3.85%. The components of lease expense were as follows (in thousands): Three Months Ended March 27, March 28, Lease expense: Operating lease expense $ 2,123 $ 1,924 Short-term lease expense 37 40 Variable lease expense 537 383 $ 2,697 $ 2,347 Future minimum payments under our non-cancelable operating leases were as follows as of March 27, 2021 (in thousands): Fiscal Year Amount Remainder of 2021 $ 6,747 2022 8,040 2023 6,710 2024 6,297 2025 7,814 Thereafter 14,416 Total minimum lease payments 50,024 Less: interest (8,982) Present value of net minimum lease payments 41,042 Less: current portion (7,557) Total long-term operating lease liabilities $ 33,485

Revenue

Revenue	3 Months Ended
	Mar. 27, 2021
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Transaction price allocated to the remaining performance obligations: On March 27, 2021, we had $6.3 million of remaining performance obligations, which were comprised of deferred service contracts and extended warranty contracts and contracts with overtime revenue recognition that are not yet delivered. We expect to recognize approximately 74.5% of our remaining performance obligations as revenue in the remainder of fiscal 2021, approximately 16.6% in fiscal 2022, and approximately 8.9% in fiscal 2023 and thereafter. The foregoing excludes the value of other remaining performance obligations as they have original durations of one year or less, and also excludes information about variable consideration allocated entirely to a wholly unsatisfied performance obligation. Contract balances: The timing of revenue recognition may differ from the timing of invoicing to customers. Accounts receivable is recorded at the invoiced amount, net of an allowance for doubtful accounts. A receivable is recognized in the period we deliver goods or provide services or when our right to consideration is unconditional. A contract asset is recorded when we have performed under the contract but our right to consideration is conditional on something other than the passage of time. Contract assets as of March 27, 2021 and December 26, 2020 were $4.8 million and $3.7 million, respectively, and are reported on the Condensed Consolidated Balance Sheets as a component of Prepaid expenses and other current assets. Contract liabilities include payments received in advance of performance under a contract and are satisfied as the associated revenue is recognized. Contract liabilities are reported on the Condensed Consolidated Balance Sheets at the end of each reporting period as a component of Deferred revenue and Other liabilities. Contract liabilities as of March 27, 2021 and December 26, 2020 were $19.9 million and $22.2 million, respectively. During the three months ended March 27, 2021, we recognized $9.3 million of revenue, that was included in contract liabilities as of December 26, 2020. Costs to obtain a contract: We generally expense sales commissions when incurred as a component of Selling, general and administrative expense, as the amortization period is typically less than one year. Revenue by Category: Refer to Note 15, Operating Segments and Enterprise-Wide Information

Operating Segments and Enterpri

Operating Segments and Enterprise-Wide Information	3 Months Ended
	Mar. 27, 2021
Segment Reporting [Abstract]
Operating Segments and Enterprise-Wide Information	Operating Segments and Enterprise-Wide Information Our chief operating decision maker (“CODM”) is our Chief Executive Officer, who reviews operating results to make decisions about allocating resources and assessing performance for the entire company. We operate in two reportable segments consisting of the Probe Cards segment and the Systems segment. The following table summarizes the operating results by reportable segment (dollars in thousands): Three Months Ended March 27, 2021 March 28, 2020 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 158,898 $ 27,738 $ — $ 186,636 $ 134,715 $ 26,038 $ — $ 160,753 Gross profit $ 70,315 $ 13,599 $ (7,208) $ 76,706 $ 60,743 $ 13,334 $ (6,687) $ 67,390 Gross margin 44.3 % 49.0 % — % 41.1 % 45.1 % 51.2 % — % 41.9 % Operating results provide useful information to our management for assessment of our performance and results of operations. Certain components of our operating results are utilized to determine executive compensation along with other measures. Corporate and Other includes unallocated expenses relating to amortization of intangible assets, inventory and fixed asset fair value adjustments due to acquisitions and share-based compensation, which are not used in evaluating the results of, or in allocating resources to, our reportable segments. Certain revenue category information by reportable segment was as follows (in thousands): Three Months Ended March 27, 2021 March 28, 2020 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 113,410 $ — $ 113,410 $ 105,745 $ — $ 105,745 DRAM 33,898 — 33,898 24,696 — 24,696 Flash 11,590 — 11,590 4,274 — 4,274 Systems — 27,738 27,738 — 26,038 26,038 Total $ 158,898 $ 27,738 $ 186,636 $ 134,715 $ 26,038 $ 160,753 Timing of revenue recognition: Products transferred at a point in time $ 158,476 $ 24,671 $ 183,147 $ 134,069 $ 24,858 $ 158,927 Products and services transferred over time 422 3,067 3,489 646 1,180 1,826 Total $ 158,898 $ 27,738 $ 186,636 $ 134,715 $ 26,038 $ 160,753 Geographical region: Taiwan $ 44,734 $ 846 $ 45,580 $ 30,439 $ 1,341 $ 31,780 China 37,831 4,794 42,625 37,280 6,362 43,642 United States 21,308 8,178 29,486 25,611 6,305 31,916 Asia-Pacific 1 27,878 1,080 28,958 4,455 3,408 7,863 South Korea 18,001 1,084 19,085 13,692 396 14,088 Europe 2,833 7,166 9,999 16,210 4,833 21,043 Japan 5,249 4,072 9,321 5,535 2,835 8,370 Rest of the world 1,064 518 1,582 1,493 558 2,051 Total $ 158,898 $ 27,738 $ 186,636 $ 134,715 $ 26,038 $ 160,753 1 Asia-Pacific includes all countries in the region except China, Japan, South Korea, and Taiwan, which are disclosed separately.

Basis of Presentation and New_2

Basis of Presentation and New Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 27, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying condensed consolidated financial information of FormFactor, Inc. is unaudited and has been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). However, such information reflects all adjustments, consisting only of normal recurring adjustments, which are, in the opinion of management, necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods. The condensed consolidated financial statements included herein should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2020 Annual Report on Form 10-K filed with the SEC on February 22, 2021. The results of operations for the interim periods presented are not necessarily indicative of the results to be expected for the full year.
Fiscal Year	Fiscal Year We operate on a 52/53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2021 and 2020 each contain 52 weeks and the three months ended March 27, 2021 and March 28, 2020 each contained 13 weeks. Fiscal 2021 will end on December 25, 2021.
Reclassifications	Reclassifications Certain immaterial reclassifications were made to the prior year financial statements to conform to the current year presentation.
New Accounting Pronouncements	New Accounting Pronouncements ASU 2019-12 In December 2019, the Financial Accounting Standard Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, “Income Taxes (Topic 740),” which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU 2019-12 on a prospective basis on December 27, 2020, the first day of fiscal 2021. The adoption did not have a material effect on our consolidated financial position, results of operations or cash flows. ASU 2020-04 In March 2020, the FASB issued ASU 2020-04, “Referenced Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The ASU provides temporary optional expedients and exceptions for applying generally accepted accounting principles to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. In January 2021, the FASB issued ASU 2021-01, “Reference Rate Reform (Topic 848),” which permits entities to apply optional expedients in Topic 848 to derivative instruments modified because of discounting transition resulting from reference rate reform. ASU 2020-04 became effective upon issuance and may be applied prospectively to contract modifications made on or before December 31, 2022. ASU 2021-01 became effective upon issuance and may be applied on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020 or prospectively for contract modifications made on or before December 31, 2022. The Company has not yet applied the relief afforded by these standard amendments and is currently assessing contracts that will require modification due to reference rate reform to which these standard amendments may be applied.
Fair Value	Whenever possible, the fair values of our financial assets and liabilities are determined using quoted market prices of identical securities or quoted market prices of similar securities from active markets. The three levels of inputs that may be used to measure fair value are as follows: • Level 1 valuations are obtained from real-time quotes for transactions in active exchange markets involving identical securities; • Level 2 valuations utilize significant observable inputs, such as quoted prices for similar assets or liabilities, quoted prices near the reporting date in markets that are less active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and • Level 3 valuations utilize unobservable inputs to the valuation methodology and include our own data about assumptions market participants would use in pricing the asset or liability based on the best information available under the circumstances. We did not have any transfers of assets or liabilities measured at fair value on a recurring basis to or from Level 1, Level 2 or Level 3 during the three months ended March 27, 2021 or the year ended December 26, 2020. The carrying values of Cash, Accounts receivable, net, Restricted cash, Prepaid expenses and other current assets, Accounts payable, Accrued liabilities, and term loans, net of unamortized issuance costs, approximate fair value due to their short maturities. No changes were made to our valuation techniques during the first three months of fiscal 2021.

Concentration of Credit and O_2

Concentration of Credit and Other Risks (Tables)	3 Months Ended
	Mar. 27, 2021
Risks and Uncertainties [Abstract]
Schedule of Customer Percentage of Revenue	Each of the following customers accounted for 10% or more of our revenues for the periods indicated: Three Months Ended March 27, March 28, Intel Corporation 28.1 % 36.2 % Taiwan Semiconductor Manufacturing Co., LTD. 11.5 % * 39.6 % 36.2 % *Represents less than 10% of total revenues.

Inventories, net (Tables)

Inventories, net (Tables)	3 Months Ended
	Mar. 27, 2021
Inventory Disclosure [Abstract]
Schedule of Inventory Components	Inventories, net, consisted of the following (in thousands): March 27, December 26, Raw materials $ 52,320 $ 48,122 Work-in-progress 35,466 30,806 Finished goods 16,941 20,301 $ 104,727 $ 99,229

Acquisition (Tables)

Acquisition (Tables)	3 Months Ended
	Mar. 27, 2021
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The estimated fair value of assets acquired, including goodwill and intangibles, and liabilities assumed is as follows (in thousands): Amount Cash and cash equivalents $ 1,680 Accounts receivable 1,017 Inventory 3,047 Property, plant and equipment 669 Operating lease, right of use assets 2,554 Prepaid expenses and other current assets 599 Tangible assets acquired 9,566 Deferred revenue (2,529) Accounts payable and accrued liabilities (1,268) Operating lease liabilities (2,554) Deferred tax liabilities (2,840) Total tangible assets acquired and liabilities assumed 375 Intangible assets 11,520 Goodwill 6,665 Net Assets Acquired $ 18,560 Amount Accounts receivable $ 4,365 Inventory 2,727 Property, plant and equipment 9,053 Operating lease, right of use assets 519 Prepaid expenses and other current assets 56 Tangible assets acquired 16,720 Accounts payable and accrued liabilities (743) Operating lease liabilities (519) Total net tangible assets acquired and liabilities assumed 15,458 Intangible assets 13,600 Goodwill 5,942 Net assets acquired $ 35,000
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The intangible assets as of the closing date of the acquisition included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 7,500 10.0 Customer relationships 3,600 5.0 Order backlog 200 0.5 Trade names 220 5.0 Total intangible assets $ 11,520 8.2 The intangible assets as of July 30, 2020 included (in thousands): Amount Weighted Average Useful Life (in years) Developed technologies $ 8,800 10.0 Customer relationships 4,400 3.0 In-process research and development 400 N/A Total intangible assets $ 13,600 7.7

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 27, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by Reportable Segments	Goodwill by reportable segment was as follows (in thousands): Probe Cards Systems Total Goodwill, gross, as of December 28, 2019 $ 172,482 $ 26,714 $ 199,196 Addition - FRT GmbH Acquisition — 975 975 Addition - Baldwin Park Acquisition 5,590 — 5,590 Addition - HPD Acquisition — 4,654 4,654 Foreign currency translation — 2,346 2,346 Goodwill, gross, as of December 26, 2020 178,072 34,689 212,761 Addition - Baldwin Park Acquisition 352 352 Addition - HPD Acquisition — 2,011 2,011 Foreign currency translation — (906) (906) Goodwill, gross, as of March 27, 2021 $ 178,424 $ 35,794 $ 214,218
Schedule of Intangible Assets	Intangible assets were as follows (in thousands): March 27, 2021 December 26, 2020 Intangible Assets Gross Accumulated Net Gross Accumulated Net Developed technologies $ 173,318 $ 142,344 $ 30,974 $ 176,265 $ 137,754 $ 38,511 Trade names 8,100 7,418 682 8,162 7,363 799 Customer relationships 51,557 34,899 16,658 52,488 33,378 19,110 Backlog 1,969 1,897 72 2,227 1,900 327 In-process research and development 400 — 400 400 — 400 $ 235,344 $ 186,558 $ 48,786 $ 239,542 $ 180,395 $ 59,147
Schedule of Amortization Expense	Amortization expense was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended March 27, March 28, Cost of revenues $ 5,090 $ 5,750 Selling, general and administrative 1,715 1,513 $ 6,805 $ 7,263
Schedule of Estimated Amortization of Intangible Assets	The estimated future amortization of definite-lived intangible assets, excluding in-process research and development, is as follows (in thousands): Fiscal Year Amount Remainder of 2021 $ 11,933 2022 9,591 2023 7,240 2024 4,625 2025 4,364 Thereafter 10,633 $ 48,386

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	3 Months Ended
	Mar. 27, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): March 27, December 26, Accrued compensation and benefits $ 28,092 $ 33,110 Accrued income and other taxes 3,008 6,976 Accrued warranty 3,719 3,918 Employee stock purchase plan contributions withheld 2,109 4,240 Accrued contingent consideration 3,884 4,012 Other accrued expenses 2,656 3,086 $ 43,468 $ 55,342

Fair Value and Derivative Ins_2

Fair Value and Derivative Instruments (Tables)	3 Months Ended
	Mar. 27, 2021
Fair Value Disclosures [Abstract]
Fair Value Assets Measured on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis were as follows (in thousands): March 27, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 34,254 $ — $ — $ 34,254 Commercial paper 5,500 — — 5,500 39,754 — — 39,754 Marketable securities: U.S. treasuries 32,669 — — 32,669 Certificates of deposit — 1,212 — 1,212 U.S. agency securities — 575 — 575 Corporate bonds — 44,146 — 44,146 Commercial paper — 15,491 — 15,491 32,669 61,424 — 94,093 Foreign exchange derivative contracts (Designated) — 144 — 144 Interest rate swap derivative contracts — 745 — 745 Total assets $ 72,423 $ 62,313 $ — $ 134,736 Liabilities: Foreign exchange derivative contracts (Designated) $ — $ (100) $ — $ (100) Interest rate swap derivative contracts — (113) — (113) Contingent consideration — — (3,884) (3,884) Total liabilities $ — $ (213) $ (3,884) $ (4,097) December 26, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 43,019 $ — $ — $ 43,019 Marketable securities: U.S. treasuries 40,726 — — 40,726 Certificates of deposit — 2,179 — 2,179 U.S. agency securities — 575 — 575 Corporate bonds — 24,330 — 24,330 40,726 27,084 — 67,810 Foreign exchange derivative contracts — 1,057 — 1,057 Interest rate swap derivative contracts — 57 — 57 Total assets $ 83,745 $ 28,198 $ — $ 111,943 Liabilities: Interest rate swap derivative contracts $ — $ (87) $ — $ (87) Contingent consideration — — (4,012) (4,012) Total liabilities $ — $ (87) $ (4,012) $ (4,099)
Schedule of the Impact of Cash Flow Hedges on Consolidated Financial Statements	The impact of the interest rate swaps on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion) Three Months Ended March 27, 2021 $ 624 Interest expense $ (38) Interest expense $ — Three Months Ended March 28, 2020 $ (96) Interest expense $ 22 Interest expense $ —
Schedule of Foreign Currency Forward Contracts	The following table provides information about our foreign currency forward contracts outstanding as of March 27, 2021 (in thousands): Currency Contract Position Contract Amount Contract Amount Euro Dollar Buy (10,141) $ (12,025) Euro Dollar Sell 11,043 13,026 Japanese Yen Buy (1,971,765) (17,977) Korean Won Sell 3,129,743 2,767 Taiwan Dollar Sell 7,972 279 Total USD notional amount of outstanding foreign exchange contracts $ (13,930) The impact of foreign exchange derivative contracts designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized in Accumulated OCI on Derivative Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Three Months Ended March 27, 2021 $ (526) Cost of revenues $ 250 Research and development 30 Selling, general and administrative 82 $ 362 Three Months Ended March 28, 2020 $ (3) Cost of revenues $ (120) Research and development (18) Selling, general and administrative (43) $ (181)
Schedule of Gains and Losses Related to Non-designated Derivative Instruments	The impact of foreign exchange derivative contracts not designated as cash flow hedges on our Condensed Consolidated Statements of Income was as follows (in thousands): Amount of Gain (Loss) Recognized on Derivatives Three Months Ended Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized on Derivatives March 27, March 28, Foreign exchange forward contracts Other income (expense), net $ 1,288 $ (115)

Warranty (Tables)

Warranty (Tables)	3 Months Ended
	Mar. 27, 2021
Product Warranties Disclosures [Abstract]
Reconciliation of Changes in Warranty Liability	Changes in our warranty liability were as follows (in thousands): Three Months Ended March 27, March 28, Balance at beginning of period $ 3,918 $ 1,942 Accruals 1,374 660 Settlements (1,573) (684) Balance at end of period $ 3,719 $ 1,918

Property, Plant, and Equipmen_2

Property, Plant, and Equipment, net (Tables)	3 Months Ended
	Mar. 27, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment, net consisted of the following (in thousands): March 27, December 26, Land $ 4,751 $ 4,751 Machinery and equipment 233,357 226,185 Computer equipment and software 43,839 36,361 Furniture and fixtures 6,925 6,894 Leasehold improvements 80,011 79,144 Sub-total 368,883 353,335 Less: Accumulated depreciation and amortization (298,865) (294,468) Net, property, plant and equipment 70,018 58,867 Construction-in-process 42,294 45,236 Total $ 112,312 $ 104,103

Stockholders_ Equity and Stoc_2

Stockholders’ Equity and Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 27, 2021
Equity [Abstract]
Schedule of Restricted Stock Unit Activity	Restricted stock unit (“RSU”) activity under our equity incentive plan was as follows: Units Weighted Average Grant Date Fair Value RSUs at December 26, 2020 2,840,922 $ 19.80 Awards granted 8,765 46.25 Awards vested (67,635) 16.38 Awards forfeited (11,140) 21.21 RSUs at March 27, 2021 2,770,912 19.96
Schedule of Stock Option Activity	Stock option activity under our equity incentive plan was as follows: Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Aggregate Intrinsic Value Outstanding at December 26, 2020 106,000 $ 8.35 Options exercised (50,000) 8.44 Outstanding at March 27, 2021 56,000 $ 8.28 0.92 $ 2,078,820 Vested and expected to vest at March 27, 2021 56,000 $ 8.28 0.92 $ 2,078,820 Exercisable at March 27, 2021 56,000 $ 8.28 0.92 $ 2,078,820
Schedule of ESPP Activity	Information related to activity under our Employee Stock Purchase Plan (“ESPP”) was as follows: Three Months Ended March 27, 2021 Shares issued 228,784 Weighted average per share purchase price $ 22.14 Weighted average per share discount from the fair value of our common stock on the date of issuance $ (18.73)
Schedule of Stock-based Compensation	Stock-based compensation was included in our Condensed Consolidated Statements of Income as follows (in thousands): Three Months Ended March 27, March 28, Cost of revenues $ 1,335 $ 937 Research and development 1,689 1,439 Selling, general and administrative 4,053 3,247 Total stock-based compensation $ 7,077 $ 5,623
Schedule of Unrecognized Stock-based Compensation	At March 27, 2021, the unrecognized stock-based compensation was as follows (dollars in thousands): Unrecognized Expense Average Expected Recognition Period in Years Restricted stock units $ 27,429 2.03 Performance restricted stock units 7,719 1.93 Employee stock purchase plan 973 0.86 Total unrecognized stock-based compensation expense $ 36,121 1.99

Net Income per Share (Tables)

Net Income per Share (Tables)	3 Months Ended
	Mar. 27, 2021
Earnings Per Share [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share	The following table reconciles the shares used in calculating basic net income per share and diluted net income per share (in thousands): Three Months Ended March 27, March 28, Weighted-average shares used in computing basic net income per share 77,598 76,005 Add potentially dilutive securities 2,390 2,505 Weighted-average shares used in computing diluted net income per share 79,988 78,510 Securities not included as they would have been antidilutive 3 9

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 27, 2021
Leases [Abstract]
Components of Lease Expense	The components of lease expense were as follows (in thousands): Three Months Ended March 27, March 28, Lease expense: Operating lease expense $ 2,123 $ 1,924 Short-term lease expense 37 40 Variable lease expense 537 383 $ 2,697 $ 2,347
Schedule of Future Minimum Payments Under Leases	Future minimum payments under our non-cancelable operating leases were as follows as of March 27, 2021 (in thousands): Fiscal Year Amount Remainder of 2021 $ 6,747 2022 8,040 2023 6,710 2024 6,297 2025 7,814 Thereafter 14,416 Total minimum lease payments 50,024 Less: interest (8,982) Present value of net minimum lease payments 41,042 Less: current portion (7,557) Total long-term operating lease liabilities $ 33,485

Operating Segments and Enterp_2

Operating Segments and Enterprise-Wide Information (Tables)	3 Months Ended
	Mar. 27, 2021
Segment Reporting [Abstract]
Schedule of Operating Results by Segment	The following table summarizes the operating results by reportable segment (dollars in thousands): Three Months Ended March 27, 2021 March 28, 2020 Probe Cards Systems Corporate and Other Total Probe Cards Systems Corporate and Other Total Revenues $ 158,898 $ 27,738 $ — $ 186,636 $ 134,715 $ 26,038 $ — $ 160,753 Gross profit $ 70,315 $ 13,599 $ (7,208) $ 76,706 $ 60,743 $ 13,334 $ (6,687) $ 67,390 Gross margin 44.3 % 49.0 % — % 41.1 % 45.1 % 51.2 % — % 41.9 %
Disaggregation of Revenue by Segment	Certain revenue category information by reportable segment was as follows (in thousands): Three Months Ended March 27, 2021 March 28, 2020 Probe Cards Systems Total Probe Cards Systems Total Market: Foundry & Logic $ 113,410 $ — $ 113,410 $ 105,745 $ — $ 105,745 DRAM 33,898 — 33,898 24,696 — 24,696 Flash 11,590 — 11,590 4,274 — 4,274 Systems — 27,738 27,738 — 26,038 26,038 Total $ 158,898 $ 27,738 $ 186,636 $ 134,715 $ 26,038 $ 160,753 Timing of revenue recognition: Products transferred at a point in time $ 158,476 $ 24,671 $ 183,147 $ 134,069 $ 24,858 $ 158,927 Products and services transferred over time 422 3,067 3,489 646 1,180 1,826 Total $ 158,898 $ 27,738 $ 186,636 $ 134,715 $ 26,038 $ 160,753 Geographical region: Taiwan $ 44,734 $ 846 $ 45,580 $ 30,439 $ 1,341 $ 31,780 China 37,831 4,794 42,625 37,280 6,362 43,642 United States 21,308 8,178 29,486 25,611 6,305 31,916 Asia-Pacific 1 27,878 1,080 28,958 4,455 3,408 7,863 South Korea 18,001 1,084 19,085 13,692 396 14,088 Europe 2,833 7,166 9,999 16,210 4,833 21,043 Japan 5,249 4,072 9,321 5,535 2,835 8,370 Rest of the world 1,064 518 1,582 1,493 558 2,051 Total $ 158,898 $ 27,738 $ 186,636 $ 134,715 $ 26,038 $ 160,753 1 Asia-Pacific includes all countries in the region except China, Japan, South Korea, and Taiwan, which are disclosed separately.

Concentration of Credit and O_3

Concentration of Credit and Other Risks (Details) - Customer Concentration Risk	3 Months Ended		12 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Dec. 26, 2020
Revenue from Contract with Customer Benchmark
Concentration Risk [Line Items]
Concentration risk percentage	39.60%	36.20%
Revenue from Contract with Customer Benchmark | Intel Corporation
Concentration Risk [Line Items]
Concentration risk percentage	28.10%	36.20%
Revenue from Contract with Customer Benchmark | Taiwan Semiconductor Manufacturing Co., LTD.
Concentration Risk [Line Items]
Concentration risk percentage	11.50%
Accounts Receivable | Major Customer 1
Concentration Risk [Line Items]
Concentration risk percentage	22.80%		15.30%
Accounts Receivable | Major Customer 2
Concentration Risk [Line Items]
Concentration risk percentage			13.70%

Inventories, net (Details)

Inventories, net (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Inventory Disclosure [Abstract]
Raw materials	$ 52,320	$ 48,122
Work-in-progress	35,466	30,806
Finished goods	16,941	20,301
Inventories	$ 104,727	$ 99,229

Acquisition - Additional Inform

Acquisition - Additional Information (Details) $ in Thousands	Oct. 19, 2020USD ($)millikelvin	Jul. 30, 2020USD ($)
Baldwin Park
Business Acquisition [Line Items]
Consideration transferred		$ 35,000
High Precision Devices, Inc.
Business Acquisition [Line Items]
Business acquisition, percentage acquired	100.00%
Consideration transferred	$ 16,900
Cash and cash equivalents	$ 1,680
High Precision Devices, Inc. | Minimum
Business Acquisition [Line Items]
Sensor markets, operating temperature | millikelvin	30

Acquisition - Assets Acquired a

Acquisition - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020	Oct. 19, 2020	Jul. 30, 2020	Dec. 28, 2019
Business Acquisition [Line Items]
Goodwill	$ 214,218	$ 212,761			$ 199,196
Baldwin Park
Business Acquisition [Line Items]
Accounts receivable				$ 4,365
Inventory				2,727
Property, plant and equipment				9,053
Operating lease, right of use assets				519
Prepaid expenses and other current assets				56
Tangible assets acquired				16,720
Accounts payable and accrued liabilities				(743)
Operating lease liabilities				(519)
Total tangible assets acquired and liabilities assumed				15,458
Intangible assets				13,600
Goodwill				5,942
Net Assets Acquired				$ 35,000
High Precision Devices, Inc.
Business Acquisition [Line Items]
Cash and cash equivalents			$ 1,680
Accounts receivable			1,017
Inventory			3,047
Property, plant and equipment			669
Operating lease, right of use assets			2,554
Prepaid expenses and other current assets			599
Tangible assets acquired			9,566
Deferred revenue			(2,529)
Accounts payable and accrued liabilities			(1,268)
Operating lease liabilities			(2,554)
Deferred tax liabilities			(2,840)
Total tangible assets acquired and liabilities assumed			375
Intangible assets			11,520
Goodwill			6,665
Net Assets Acquired			$ 18,560

Acquisition - Intangible Assets

Acquisition - Intangible Assets Acquired (Details) - USD ($) $ in Thousands	Oct. 19, 2020	Jul. 30, 2020
High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 11,520
Weighted Average Useful Life (in years)	8 years 2 months 12 days
Baldwin Park
Business Acquisition [Line Items]
Amount		$ 13,600
Weighted Average Useful Life (in years)		7 years 8 months 12 days
Baldwin Park | In-process research and development
Business Acquisition [Line Items]
Amount		$ 400
Developed technologies | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 7,500
Weighted Average Useful Life (in years)	10 years
Developed technologies | Baldwin Park
Business Acquisition [Line Items]
Amount		$ 8,800
Weighted Average Useful Life (in years)		10 years
Customer relationships | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 3,600
Weighted Average Useful Life (in years)	5 years
Customer relationships | Baldwin Park
Business Acquisition [Line Items]
Amount		$ 4,400
Weighted Average Useful Life (in years)		3 years
Order backlog | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 200
Weighted Average Useful Life (in years)	6 months
Trade names | High Precision Devices, Inc.
Business Acquisition [Line Items]
Amount	$ 220
Weighted Average Useful Life (in years)	5 years

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 27, 2021	Dec. 26, 2020
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 212,761	$ 199,196
Foreign currency translation	(906)	2,346
Goodwill, ending balance	214,218	212,761
FRT GmbH
Goodwill [Roll Forward]
Goodwill, acquired during period		975
Baldwin Park
Goodwill [Roll Forward]
Goodwill, acquired during period	352	5,590
High Precision Devices, Inc.
Goodwill [Roll Forward]
Goodwill, acquired during period	2,011	4,654
Probe Cards
Goodwill [Roll Forward]
Goodwill, beginning balance	178,072	172,482
Foreign currency translation	0	0
Goodwill, ending balance	178,424	178,072
Probe Cards | FRT GmbH
Goodwill [Roll Forward]
Goodwill, acquired during period		0
Probe Cards | Baldwin Park
Goodwill [Roll Forward]
Goodwill, acquired during period	352	5,590
Probe Cards | High Precision Devices, Inc.
Goodwill [Roll Forward]
Goodwill, acquired during period	0	0
Systems
Goodwill [Roll Forward]
Goodwill, beginning balance	34,689	26,714
Foreign currency translation	(906)	2,346
Goodwill, ending balance	35,794	34,689
Systems | FRT GmbH
Goodwill [Roll Forward]
Goodwill, acquired during period		975
Systems | Baldwin Park
Goodwill [Roll Forward]
Goodwill, acquired during period		0
Systems | High Precision Devices, Inc.
Goodwill [Roll Forward]
Goodwill, acquired during period	$ 2,011	$ 4,654

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Additional information (Details)	3 Months Ended
	Mar. 27, 2021USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, impairment loss	$ 0

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Finite-Lived Intangible Assets [Line Items]
Gross	$ 235,344	$ 239,542
Accumulated Amortization	186,558	180,395
Net	48,786	59,147
Developed technologies
Finite-Lived Intangible Assets [Line Items]
Gross	173,318	176,265
Accumulated Amortization	142,344	137,754
Net	30,974	38,511
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross	8,100	8,162
Accumulated Amortization	7,418	7,363
Net	682	799
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross	51,557	52,488
Accumulated Amortization	34,899	33,378
Net	16,658	19,110
Order backlog
Finite-Lived Intangible Assets [Line Items]
Gross	1,969	2,227
Accumulated Amortization	1,897	1,900
Net	72	327
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Gross	400	400
Accumulated Amortization	0	0
Net	$ 400	$ 400

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 6,805	$ 7,263
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]
Remainder of 2021	11,933
2022	9,591
2023	7,240
2024	4,625
2025	4,364
Thereafter	10,633
Net	48,386
Cost of revenues
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	5,090	5,750
Selling, general and administrative
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 1,715	$ 1,513

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 28,092	$ 33,110
Accrued income and other taxes	3,008	6,976
Accrued warranty	3,719	3,918
Employee stock purchase plan contributions withheld	2,109	4,240
Accrued contingent consideration	3,884	4,012
Other accrued expenses	2,656	3,086
Accrued liabilities	$ 43,468	$ 55,342

Fair Value and Derivative Ins_3

Fair Value and Derivative Instruments - Fair Value Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	$ 39,754
Marketable securities	94,093	$ 67,810
Total assets	134,736	111,943
Contingent consideration	(3,884)	(4,012)
Total liabilities	(4,097)	(4,099)
Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	(100)
Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	144	1,057
Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	745	57
Derivative liability	(113)	(87)
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	34,254	43,019
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	5,500
Marketable securities	15,491
U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	32,669	40,726
Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	1,212	2,179
U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	575	575
Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	44,146	24,330
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	39,754
Marketable securities	32,669	40,726
Total assets	72,423	83,745
Contingent consideration	0	0
Total liabilities	0	0
Level 1 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	0
Level 1 | Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Level 1 | Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Derivative liability	0	0
Level 1 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	34,254	43,019
Level 1 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	5,500
Marketable securities	0
Level 1 | U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	32,669	40,726
Level 1 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 1 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 1 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0
Marketable securities	61,424	27,084
Total assets	62,313	28,198
Contingent consideration	0	0
Total liabilities	(213)	(87)
Level 2 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	(100)
Level 2 | Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	144	1,057
Level 2 | Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	745	57
Derivative liability	(113)	(87)
Level 2 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Level 2 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0
Marketable securities	15,491
Level 2 | U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 2 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	1,212	2,179
Level 2 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	575	575
Level 2 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	44,146	24,330
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0
Marketable securities	0	0
Total assets	0	0
Contingent consideration	(3,884)	(4,012)
Total liabilities	(3,884)	(4,012)
Level 3 | Foreign exchange derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	0
Level 3 | Foreign exchange derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Level 3 | Interest rate swap derivative contracts | Designated as hedging instrument
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative contracts	0	0
Derivative liability	0	0
Level 3 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Level 3 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0
Marketable securities	0
Level 3 | U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 3 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 3 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
Level 3 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	$ 0	$ 0

Fair Value and Derivative Ins_4

Fair Value and Derivative Instruments - Additional Information (Details) $ in Thousands, € in Millions	Oct. 09, 2019EUR (€)	Mar. 27, 2021USD ($)	Dec. 26, 2020USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration | $		$ 3,884	$ 4,012
FRT
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration, calculation amount, multiple of EBIT	150.00%
FRT | Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration | €	€ 10.3

Fair Value and Derivative Ins_5

Fair Value and Derivative Instruments - Impact of Cash Flow Hedges and Derivatives (Details) - Designated as hedging instrument - Interest rate contracts - Cash flow hedging - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 624	$ (96)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ (38)	$ 22

Fair Value and Derivative Ins_6

Fair Value and Derivative Instruments - Foreign Currency Forward Contracts (Details) - Mar. 27, 2021 - Foreign exchange forward contracts € in Thousands, ₩ in Thousands, ¥ in Thousands, $ in Thousands, $ in Thousands	EUR (€)	USD ($)	JPY (¥)	KRW (₩)	TWD ($)
Derivative [Line Items]
Derivative, notional amount		$ (13,930)
Buy | Euro Dollar
Derivative [Line Items]
Derivative, notional amount	€ (10,141)	(12,025)
Buy | Japanese Yen
Derivative [Line Items]
Derivative, notional amount		(17,977)	¥ (1,971,765)
Sell | Euro Dollar
Derivative [Line Items]
Derivative, notional amount	€ (11,043)	(13,026)
Sell | Korean Won
Derivative [Line Items]
Derivative, notional amount		(2,767)		₩ (3,129,743)
Sell | Taiwan Dollar
Derivative [Line Items]
Derivative, notional amount		$ (279)			$ (7,972)

Fair Value and Derivative Ins_7

Fair Value and Derivative Instruments - Gains and Losses Related to Non-designated Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Derivatives Not Designated as Hedging Instruments | Foreign exchange forward contracts | Location of Gain (Loss) Recognized on Derivatives
Derivatives, Fair Value [Line Items]
Derivatives Not Designated as Hedging Instruments	$ 1,288	$ (115)

Fair Value and Derivative Ins_8

Fair Value and Derivative Instruments - Impact of Foreign Exchange Derivattive Contracts Designated as Cash Flow Hedges (Details) - Foreign exchange forward contracts - Designated as hedging instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated OCI on Derivative	$ (526)	$ (3)
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	362	(181)
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	250	(120)
Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	30	(18)
Selling, general and administrative
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	$ 82	$ (43)

Fair Value and Derivative Ins_9

Fair Value and Derivative Instruments - Assets Measured at Fair Value on a Non-Recurring Basis (Details) - USD ($)	Mar. 27, 2021	Dec. 26, 2020	Mar. 28, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on non-recurring basis	$ 134,736,000	$ 111,943,000
Liabilities measured at fair value on non-recurring basis	4,097,000	$ 4,099,000
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on non-recurring basis	0		$ 0
Liabilities measured at fair value on non-recurring basis	$ 0		$ 0

Warranty (Details)

Warranty (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance at beginning of period	$ 3,918	$ 1,942
Accruals	1,374	660
Settlements	(1,573)	(684)
Balance at end of period	$ 3,719	$ 1,918

Property, Plant, and Equipmen_3

Property, Plant, and Equipment, net (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Property, Plant and Equipment [Line Items]
Sub-total	$ 368,883	$ 353,335
Less: Accumulated depreciation and amortization	(298,865)	(294,468)
Net, property, plant and equipment	70,018	58,867
Construction-in-process	42,294	45,236
Total	112,312	104,103
Land
Property, Plant and Equipment [Line Items]
Sub-total	4,751	4,751
Machinery and equipment
Property, Plant and Equipment [Line Items]
Sub-total	233,357	226,185
Computer equipment and software
Property, Plant and Equipment [Line Items]
Sub-total	43,839	36,361
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Sub-total	6,925	6,894
Leasehold improvements
Property, Plant and Equipment [Line Items]
Sub-total	$ 80,011	$ 79,144

Stockholders_ Equity and Stoc_3

Stockholders’ Equity and Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 27, 2021	Oct. 26, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase of common stock through repurchase program	$ (5,738,000)
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program authorized amount		$ 50,000,000
Purchase of common stock through repurchase program (in shares)	(136,402)
Amount remaining for future repurchases	$ 44,300,000
Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	0

Stockholders_ Equity and Stoc_4

Stockholders’ Equity and Stock-Based Compensation - Restricted Stock Unit Activity (Details) - Equity Incentive Plan	3 Months Ended
	Mar. 27, 2021$ / sharesshares
Units
Awards granted (in shares)	0
Restricted Stock Units
Units
Beginning balance (in shares)	2,840,922
Awards granted (in shares)	8,765
Awards vested (in shares)	(67,635)
Awards canceled (in shares)	(11,140)
Ending balance (in shares)	2,770,912
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 19.80
Awards granted (in dollars per share) | $ / shares	46.25
Awards vested (in dollars per share) | $ / shares	16.38
Awards canceled (in dollars per share) | $ / shares	21.21
Ending balance (in dollars per share) | $ / shares	$ 19.96

Stockholders_ Equity and Stoc_5

Stockholders’ Equity and Stock-Based Compensation - Stock Option Activity (Details) - Equity Incentive Plan $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 27, 2021USD ($)$ / sharesshares
Options Outstanding
Outstanding, beginning of period (in shares) | shares	106,000
Options exercised (in shares) | shares	(50,000)
Outstanding, end of period (in shares) | shares	56,000
Vested and expected to vest (in shares) | shares	56,000
Exercisable (in shares) | shares	56,000
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 8.35
Options exercised (in dollars per share) | $ / shares	8.44
Outstanding, end of period (in dollars per share) | $ / shares	8.28
Vested and expected to vest (in dollars per share) | $ / shares	8.28
Exercisable (in dollars per share) | $ / shares	$ 8.28
Additional Disclosures
Outstanding, weighted average remaining contractual life	11 months 1 day
Vested and expected to vest, weighted average remaining contractual life	11 months 1 day
Exercisable, weighted average remaining contractual life	11 months 1 day
Outstanding, aggregate intrinsic value | $	$ 2,078,820
Vested end expected to vest, aggregate intrinsic value | $	2,078,820
Exercisable, aggregate intrinsic value | $	$ 2,078,820

Stockholders_ Equity and Stoc_6

Stockholders’ Equity and Stock-Based Compensation - ESPP Activity (Details) - Employee stock purchase plan	3 Months Ended
	Mar. 27, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares) | shares	228,784
Weighted average per share purchase price (in dollars per share)	$ 22.14
Weighted average per share discount from the fair value of our common stock on the date of issuance (in dollars per share)	$ (18.73)

Stockholders_ Equity and Stoc_7

Stockholders’ Equity and Stock-Based Compensation - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 7,077	$ 5,623
Cost of revenues
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,335	937
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,689	1,439
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 4,053	$ 3,247

Stockholders_ Equity and Stoc_8

Stockholders’ Equity and Stock-Based Compensation - Unrecognized Compensation Costs (Details) $ in Thousands	3 Months Ended
	Mar. 27, 2021USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 36,121
Average Expected Recognition Period in Years	1 year 11 months 26 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 27,429
Average Expected Recognition Period in Years	2 years 10 days
Performance restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 7,719
Average Expected Recognition Period in Years	1 year 11 months 4 days
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 973
Average Expected Recognition Period in Years	10 months 9 days

Net Income per Share (Details)

Net Income per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Earnings Per Share [Abstract]
Weighted-average shares used in computing basic net income per share (in shares)	77,598	76,005
Add potentially dilutive securities (in shares)	2,390	2,505
Weighted-average shares used in computing diluted net income per share (in shares)	79,988	78,510
Securities not included as they would have been antidilutive (in shares)	3	9

Leases - Narrative (Details)

Leases - Narrative (Details)	Mar. 27, 2021
Lessee, Lease, Description [Line Items]
Operating lease, renewal term	20 years
Operating lease, weighted average remaining lease term	6 years
Operating lease, weighted average discount rate	3.85%
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	8 years
Automobiles | Minimum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	1 year
Automobiles | Maximum
Lessee, Lease, Description [Line Items]
Operating lease, term of contract	4 years

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Leases [Abstract]
Operating lease expense	$ 2,123	$ 1,924
Short-term lease expense	37	40
Variable lease expense	537	383
Total lease expense	$ 2,697	$ 2,347

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Payments Under Leases (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Leases [Abstract]
Remainder of 2021	$ 6,747
2022	8,040
2023	6,710
2024	6,297
2025	7,814
Thereafter	14,416
Total minimum lease payments	50,024
Less: interest	(8,982)
Present value of net minimum lease payments	41,042
Less: current portion	(7,557)	$ (6,704)
Long-term operating lease liabilities	$ 33,485	$ 27,996

Revenue - Additional Informatio

Revenue - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 27, 2021	Dec. 26, 2020
Revenue from Contract with Customer [Abstract]
Performance obligations	$ 6.3
Contract assets	4.8	$ 3.7
Contract liabilities	19.9	$ 22.2
Revenue recognized included in contracts	$ 9.3

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details)	Mar. 27, 2021
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-03-28
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	74.50%
Revenue, remaining performance obligation, expected timing of satisfaction, period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-12-26
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	16.60%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	8.90%
Revenue, remaining performance obligation, expected timing of satisfaction, period

Operating Segments and Enterp_3

Operating Segments and Enterprise-Wide Information - Additional Information (Details)	3 Months Ended
	Mar. 27, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	2

Operating Segments and Enterp_4

Operating Segments and Enterprise-Wide Information - Operating Results by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Segment Reporting Information [Line Items]
Revenues	$ 186,636	$ 160,753
Gross profit	$ 76,706	$ 67,390
Gross margin	41.10%	41.90%
Probe Cards
Segment Reporting Information [Line Items]
Revenues	$ 158,898	$ 134,715
Systems
Segment Reporting Information [Line Items]
Revenues	27,738	26,038
Operating segments | Probe Cards
Segment Reporting Information [Line Items]
Revenues	158,898	134,715
Gross profit	$ 70,315	$ 60,743
Gross margin	44.30%	45.10%
Operating segments | Systems
Segment Reporting Information [Line Items]
Revenues	$ 27,738	$ 26,038
Gross profit	$ 13,599	$ 13,334
Gross margin	49.00%	51.20%
Operating segments | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0
Gross profit	$ (7,208)	$ (6,687)
Gross margin	0.00%	0.00%

Operating Segments and Enterp_5

Operating Segments and Enterprise-Wide Information - Revenue by Segment, Recognition Type, and Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 186,636	$ 160,753
Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	158,898	134,715
Systems
Disaggregation of Revenue [Line Items]
Revenues	27,738	26,038
Taiwan
Disaggregation of Revenue [Line Items]
Revenues	45,580	31,780
Taiwan | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	44,734	30,439
Taiwan | Systems
Disaggregation of Revenue [Line Items]
Revenues	846	1,341
China
Disaggregation of Revenue [Line Items]
Revenues	42,625	43,642
China | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	37,831	37,280
China | Systems
Disaggregation of Revenue [Line Items]
Revenues	4,794	6,362
United States
Disaggregation of Revenue [Line Items]
Revenues	29,486	31,916
United States | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	21,308	25,611
United States | Systems
Disaggregation of Revenue [Line Items]
Revenues	8,178	6,305
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	28,958	7,863
Asia-Pacific | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	27,878	4,455
Asia-Pacific | Systems
Disaggregation of Revenue [Line Items]
Revenues	1,080	3,408
South Korea
Disaggregation of Revenue [Line Items]
Revenues	19,085	14,088
South Korea | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	18,001	13,692
South Korea | Systems
Disaggregation of Revenue [Line Items]
Revenues	1,084	396
Europe
Disaggregation of Revenue [Line Items]
Revenues	9,999	21,043
Europe | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	2,833	16,210
Europe | Systems
Disaggregation of Revenue [Line Items]
Revenues	7,166	4,833
Japan
Disaggregation of Revenue [Line Items]
Revenues	9,321	8,370
Japan | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	5,249	5,535
Japan | Systems
Disaggregation of Revenue [Line Items]
Revenues	4,072	2,835
Rest of the world
Disaggregation of Revenue [Line Items]
Revenues	1,582	2,051
Rest of the world | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	1,064	1,493
Rest of the world | Systems
Disaggregation of Revenue [Line Items]
Revenues	518	558
Products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenues	183,147	158,927
Products transferred at a point in time | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	158,476	134,069
Products transferred at a point in time | Systems
Disaggregation of Revenue [Line Items]
Revenues	24,671	24,858
Products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenues	3,489	1,826
Products and services transferred over time | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	422	646
Products and services transferred over time | Systems
Disaggregation of Revenue [Line Items]
Revenues	3,067	1,180
Foundry & Logic
Disaggregation of Revenue [Line Items]
Revenues	113,410	105,745
Foundry & Logic | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	113,410	105,745
Foundry & Logic | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0
DRAM
Disaggregation of Revenue [Line Items]
Revenues	33,898	24,696
DRAM | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	33,898	24,696
DRAM | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0
Flash
Disaggregation of Revenue [Line Items]
Revenues	11,590	4,274
Flash | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	11,590	4,274
Flash | Systems
Disaggregation of Revenue [Line Items]
Revenues	0	0
Systems
Disaggregation of Revenue [Line Items]
Revenues	27,738	26,038
Systems | Probe Cards
Disaggregation of Revenue [Line Items]
Revenues	0	0
Systems | Systems
Disaggregation of Revenue [Line Items]
Revenues	$ 27,738	$ 26,038

Uncategorized Items - form-2021

Label	Element	Value
Restricted Cash, Noncurrent	us-gaap_RestrictedCashNoncurrent	$ 1,894,000
Restricted Cash, Noncurrent	us-gaap_RestrictedCashNoncurrent	1,361,000
Restricted Cash, Current	us-gaap_RestrictedCashCurrent	2,798,000
Restricted Cash, Current	us-gaap_RestrictedCashCurrent	$ 2,107,000