SCHEDULE 14A

(Rule 14A-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  x☒                             Filed by a Party other than the Registrant  ¨☐

Check the appropriate box:

ULTRA CLEAN HOLDINGS, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if Other Than the Registrant)

Payment of Filing Fee (Check the appropriate box):

ULTRA CLEAN HOLDINGS, INC.

26462 Corporate Avenue

Hayward, CA 94545

NOTICE OF 20152018 ANNUAL MEETING OF STOCKHOLDERS OF

ULTRA CLEAN HOLDINGS, INC.

Meeting begins at 12:30 p.m. Pacific time

1600 El Camino Real

Menlo Park, CA 94025

Sincerely,

/s/ James P. Scholhamer

James P. Scholhamer

Chief Executive Officer

April 27, 201519, 2018

ULTRA CLEAN HOLDINGS, INC.

20152018 ANNUAL MEETING OF STOCKHOLDERS

NOTICE OF ANNUAL MEETING AND PROXY STATEMENT

TABLE OF CONTENTS

ULTRA CLEAN HOLDINGS, INC.

26462 Corporate Avenue

Hayward, CA 94545

PROXY STATEMENT FOR 20152018 ANNUAL MEETING OF STOCKHOLDERS

June 4, 2015May 15, 2018

INFORMATION CONCERNING SOLICITATION AND VOTING

Your vote is very important. For this reason our Board of Directors is requesting that you permit your shares of common stock to be represented at our 20152018 Annual Meeting of Stockholders by the proxies named on the enclosed proxy card. This proxy statement contains important information for you to consider in deciding how to vote on the matters brought before the meeting. The date of this proxy statement is April 27, 2015.19, 2018. The proxy statement and form of proxy are first being mailed to our stockholders on or about May 5, 2015.April 20, 2018.

Important Notice Regarding The Availability Of Proxy Materials For The Stockholder Meeting To Be Held On June 4, 2015:May 15, 2018: This Proxy Statement, along with our 20142017 Annual Report to Stockholders, areis available on the following website: http://materials.proxyvote.com/90385V.

General Information

Ultra Clean Holdings, Inc., referred to in this proxy statement as “Ultra Clean,” the “Company” or “we,” is soliciting the enclosed proxy for use at our Annual Meeting of Stockholders to be held on June 4, 2015May 15, 2018 at 12:30 p.m., Pacific time or at any adjournment thereof for the purposes set forth in this proxy statement. Our annual meeting will be held at the offices of Davis Polk & Wardwell LLP, 1600 El Camino Real, Menlo Park, California 94025.

Who May Attend and Vote at Our Annual Meeting

All holders of our common stock, as reflected in our records at the close of business on April 2, 2015,March 21, 2018, the record date for voting, may attend and vote at the meeting. To attend the annual meeting, you must present photo identification for admittance. If you are not a stockholder of record but hold shares as a beneficial owner in street name, you must also provide proof of beneficial ownership as of the record date, such as your most recent account statement prior to the record date, a copy of the voting instruction card provided by your broker, bank, trustee, or nominee, or other similar evidence of ownership.

Each share of common stock that you owned on the record date entitles you to one vote on each matter properly brought before the meeting. As of the record date, there were issued and outstanding 31,615,18538,718,173 shares of our common stock, $0.001 par value.

Holding Shares as a “Beneficial Owner” (or in “Street Name”)

Most stockholders are considered the “beneficial owners” of their shares, that is, they hold their shares through a broker, bank or nominee rather than directly in their own names. As summarized below, there are some distinctions between shares held of record and those owned beneficially or in “street name.”

Stockholder of Record. If your shares are registered directly in your name with our transfer agent, you are considered the stockholder of record with respect to those shares. If you are a stockholder of record, we are sending paper copies of the proxy materials directly to you. As our stockholder of record, you have the right to grant your voting proxy directly to us by signing and mailing the enclosed proxy card to voteor by voting on the Internet, by telephone, or in person at the annual meeting.

Beneficial Owner. If your shares are held in a stock brokerage account or by a bank or nominee, you are considered the beneficial owner of shares held in street name, and the proxy statement is being forwarded to you by or on behalf of your broker, bank or nominee (who is considered the stockholder of record with respect to those shares). As the beneficial owner, you have the right to direct your broker, bank, or nominee how to vote by following the instructions you receive from your broker, bank or nominee. You are also invited to attend the annual meeting. However, since you are not the stockholder of record, you may not vote these shares in person at the annual meeting unless you request, complete and deliver a proxy from your broker, bank or nominee.

How to Vote

You may vote in person at the meeting or by proxy. You

Voting by Proxy.If you are a stockholder of record, you may vote by proxy over the Internet, by telephone or by mail if you complete and return the enclosed proxy card by following the instructions on the proxy card. If your shares are held in street name, you have the right to direct your broker, bank, or nominee how to vote by following the instructions you receive from your broker, bank or nominee. The shares voted electronically, telephonically, or represented by the proxy cards received, properly marked, dated, signed and not revoked, will be voted at the annual meeting. We recommend that you vote by proxy even if you plan to attend the meeting. You may change your vote at the meeting even if you have previously submitted a proxy.

Voting at the Annual Meeting. The method or timing of your vote will not limit your right to vote at the annual meeting if you attend the annual meeting and vote in person. However, if your shares are held in the name of a bank, broker or other nominee, you must obtain a legal proxy, executed in your favor, from the holder of record to be able to vote at the annual meeting. You should allow yourself enough time prior to the annual meeting to obtain this proxy from the holder of record.

How Proxies Work

This proxy statement is furnished in connection with the solicitation of proxies by us for use at the annual meeting and at any adjournment of that meeting. If you give us your proxy you authorize us to vote your shares at the meeting in the manner you direct. You may vote for all, some or none of our director candidates. You may also vote for or against the other proposals, or you may abstain from voting.

If you give us your proxy but do not specify how your shares shall be voted on a particular matter, your shares will be voted:

Changing or Revoking Your Vote

You have the right to revoke your previously submitted proxy at any time before your proxy is exercised at the annual meeting.

YouIf you are the stockholder of record, you may revoke your proxy by resubmitting your vote on a later date on the Internet or by telephone (only your latest Internet or telephone proxy submitted prior to the annual meeting will be counted), by signing and returning a new proxy card with a later date, by attending the annual meeting and voting in person or by giving written notice to our Secretary that you wish to revoke your previously submitted proxy.

If you hold shares beneficially in street name, you may revoke your proxy by submitting new voting instructions to your broker, bank or nominee by following the instructions they provided or, if you have obtained a legal proxy from your broker, bank or nominee giving you the right to vote your shares, by attending the annual meeting and voting in person.

Note that for both stockholders of record and beneficial owners, attendance at the annual meeting will not cause your previously granted proxy to be revoked unless you specifically so request or vote in person at the annual meeting.

Important Notice Regarding Delivery of Stockholder Documents

Only one proxy statement, annual report and set of accompanying materials, if applicable, are being delivered by us to multiple stockholders sharing an address, who have consented to receiving one set of such materials, until we receive contrary instructions from any such stockholders. We will deliver, promptly upon written or oral request, a separate copy of such materials to a stockholder at a shared address to which a single copy of such materials was delivered. A stockholder who wishes to receive a separate copy of the proxy statement and accompanying materials now or in the future, or stockholders sharing an address who are receiving multiple copies of the proxy statement and accompanying materials and wish to receive a single copy of such materials, should submit a request to Broadridge, c/o Householding Department, 51 Mercedes Way, Edgewood, NY 11717 or call800-542-1061.

Attending in Person

Any stockholder of record may vote in person at the annual meeting of our stockholders. All meeting attendees will be required to present a valid, government-issued photo identification, such as a driver’s license or passport, in order to enter the meeting.

If you are a beneficial owner and your shares are held in the name of your broker, bank or nominee, you must bring a proxy from your broker, bank or nominee in order to vote in person.

Votes Needed to Hold the Meeting and Approve Proposals

In order to carry on the business of the annual meeting, stockholders entitled to cast a majority of the votes at a meeting of stockholders must be represented at the meeting, either in person or by proxy. In accordance with Delaware law, only votes cast “for” a matter constitute affirmative votes. A properly executed proxy marked “abstain” with respect to any matter will not be voted, although it will be counted for purposes of determining whether there is a quorum. Since abstentions will not be votes cast for a particular proposal, they will have the same effect as negative votes or votes against that proposal. Brokernon-votes are also counted for the purpose of determining the presence of a quorum. Brokernon-votes occur when shares held by a broker on behalf of a beneficial owner are not voted with respect to a particular proposal, which generally occurs when the broker has not received voting instructions from the beneficial owner and lacks the discretionary authority to vote the shares itself.

Election of Directors. The election of directors requiresOur Amended and Restated Bylaws provides that a pluralitydirector nominee must receive a majority of the votes cast with respect to such nominee in uncontested director elections (i.e., the number of shares voted “for” a director nominee must exceed the number of shares voted “against” such nominee). If an incumbent director nominee fails to receive a majority of the votes cast in an uncontested election, the director shall immediately tender his or her resignation to the Board. The Nominating and Corporate Governance Committee of the Board, or such other committee designated by the Board, shall make a recommendation to the Board as to whether to accept or reject the resignation of such incumbent director, or whether other action should be taken. The Board shall act on the resignation, taking into account the committee’s recommendation, and publicly disclose its decision regarding the resignation within 90 days following certification of the election

results. If the Board accepts a director’s resignation, or if a nominee for director is not elected and the nominee is not an incumbent director, the remaining members of directors. “Plurality” means that the seven nominees who receiveBoard may fill the highest numberresulting vacancy or may decrease the size of votes will be elected as directors. In the election of directors, votes may be cast in favor of or withheld from any or all nominees. Board.

Brokers do not have discretionary authority to vote shares without instructions from beneficial owners in the election of directors. Therefore, beneficial owners who are not stockholders of record and who want their votes to be counted in the election of directors must give voting instructions to their bank, broker or nominee before the date of the annual meeting.

Ratification of the appointment of our independent registered public accounting firm. The affirmative vote of the holders of a majority of the shares of common stock present in person or represented by proxy and entitled to vote on the proposal will be required to ratify the appointment of our independent registered public accounting firm for the current fiscal year. We believe that the ratification of our independent registered public accounting firm is a routine proposal for which brokers may vote shares held on behalf of beneficial owners who have not given voting instructions with respect to that proposal.

Advisory vote on the compensation of our named executive officers. The affirmative vote of the holders of a majority of the shares of common stock present in person or represented by proxy and entitled to vote on the proposal will be requiredsufficient to approve, by an advisory,non-binding vote, the compensation of our named executive officers for fiscal 2014.2017. The advisory vote on the compensation of our named executive officers, while held annually, is not considered a routine proposal; therefore, brokers lack the discretionary authority to vote shares without instructions from beneficial owners for this proposal.

Approval of any other matter properly submitted to the stockholders at the annual meeting generally will require the affirmative vote of the holders of a majority of the shares of common stock present in person or represented by proxy and entitled to vote on that matter.

Security Ownership of Certain Beneficial Owners and Management

The table below sets forth information as of March 27, 201521, 2018 (the record date for our 2018 Annual Meeting) regarding the beneficial ownership (as defined by Rule13d-3(d)(1) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) of our common stock by:

In accordance with applicable rules of the Securities and Exchange Commission (the “SEC”), beneficial ownership includes voting or investment power with respect to securities and includes the shares issuable pursuant to stock options that are exercisable, and shares of restricted stock andsubject to restricted stock units that vest and are delivered, within 60 days of March 27, 2015.21, 2018. Shares issuable pursuant to the exercise of stock options, and shares of restricted stock and restricted stock units that vest, in the 60 days following March 27, 2015,21, 2018, are deemed outstanding for the purpose of computing the ownership percentage of the person holding such options, or shares of restricted stock orsubject to restricted stock units, but are not deemed outstanding for computing the ownership percentage of any other person. The percentage of beneficial ownership for the following table is based on 31,485,45938,718,173 shares of common stock outstanding as of March 27, 2015.21, 2018.

The address of each of the named individuals in the table below is c/o Ultra Clean Holdings, Inc., 26462 Corporate Avenue, Hayward, CA 94545 unless otherwise indicated below. To our knowledge, except as indicated in the footnotes to this table and pursuant to applicable community property laws, the persons named in the table have sole voting and investment power with respect to all shares of common stock.

(1)	Based on a Schedule 13G/A filed with the SEC on January 21, 2015.February 9, 2018.

(10)	Includes 7,500 restricted stock awards that vest on May 14, 2018. Also includes 15,000 shares held by the Revocable Trust of Leonid Mezhvinsky and Inna Mezhvinsky, dated April 26, 1988, for which Mr. Mezhvinsky is deemed a beneficial owner.

At the close of business on April 2, 2015,March 21, 2018, the record date, we had 31,615,18538,718,173 shares of common stock outstanding. Each share of our common stock is entitled to one vote on all matters properly submitted for a stockholder vote.

Section 16(a) Beneficial Ownership Reporting Compliance

Section 16(a) requires our directors, executive officers and beneficial holders of 10% or more of a registered class of our equity securities to file certain reports with the SEC regarding ownership of, and transactions in, our equity securities. We have reviewed copiesBased solely on a review of the reports we receivedForms 3, 4 and 5 and amendments thereto furnished to us and written representations we received from our directors and officers required to file the reports.

Based solely on our review of such reports, and representations, except as described in the following paragraph, we believe that all of our directors, executive officers and beneficial holders of 10% or more of a registered class of our equity securities, filed, on a timely basis, all reports required by Section 16(a) of the Exchange Act for the year ended December 26, 2014.29, 2017, except:

One

Cost of Proxy Solicitation

We will pay the cost of this proxy solicitation. Some of our employees may also solicit proxies, without any additional compensation. We may also reimburse banks, brokerage firms and nominees for their expenses in forwarding proxy materials to their customers who are beneficial owners of our common stock and obtaining their voting instructions.

Deadline for Receipt of Stockholder Proposals

If you wish to submit a proposal for inclusion in the proxy statement for our 20162019 Annual Meeting of Stockholders, you must follow the procedures outlined in Rule14a-8 of the Exchange Act, and we must receive your proposal at the address below no later than January 6, 2016.December 21, 2018. Stockholders intending to present a proposal at the next annual meeting without the inclusion of such proposal in the Company’s proxy materials, including for the election of director nominees, must comply with the requirements set forth in our bylaws.Amended and Restated Bylaws. The bylawsAmended and Restated Bylaws require, among other things, that a stockholder must submit a written notice of intent to present such a proposal at the address below not less than 90 days nor more than 120 days prior to the first anniversary of the preceding year’s annual meeting of stockholders (as long as the date of the annual meeting is not advanced more than 30 days prior to such anniversary date or delayed more than 70 days after such anniversary date, in which case notice must be received no earlier than 120 days prior to such meeting and no later than the later of 70 days prior to such meeting or the 10th day following the public announcement of the date of such meeting). Therefore, we must receive notice of such proposal for the 20162019 Annual Meeting of Stockholders no earlier than February 5, 2016January 15, 2019, and no later than March 6, 2016,February 14, 2019, otherwise such notice will be considered untimely and we will not be required to present it at the 20162019 Annual Meeting of

Stockholders. The Company reserves the right to reject, rule out of order or take other appropriate action with respect to any proposal that does not comply with these and other applicable requirements.

Contacting Ultra Clean

If you have questions or would like more information about the annual meeting, you can contact us in either of the following ways:

PROPOSAL 1: ELECTION OF DIRECTORS

Our Amended and Restated Bylaws provide that our Board of Directors shall be elected at the annual meeting of our stockholders, and each director so elected shall hold office until such director’s successor is elected and qualified or until such director’s earlier death, resignation or removal. Our Board of Directors, at the recommendation of the Nominating and Corporate Governance Committee, has recommended for nomination the nominees for director named below. All of these nominees other than Thomas T. Edman and Barbara V. Scherer, currently serve as our directors. Each nominee has consented to serve as a nominee, to serve as a director if elected, and to being named a nominee in this Proxy Statement. Susan Billat will not stand for reelection at the 2015 Annual Meeting of Stockholders. If a director nominee becomes unavailable before the election, your proxy authorizes the people named as proxies to vote for a replacement nominee if our Board of Directors names one.

Our Amended and Restated Bylaws provide that a director nominee must receive a majority of the votes cast with respect to such nominee in uncontested director elections (i.e., the number of shares voted “for” a director nominee must exceed the number of shares voted “against” such nominee). If an incumbent director nominee fails to receive a majority of the votes cast in an uncontested election, the director shall immediately tender his or her resignation to the Board. The Nominating and Corporate Governance Committee names one.of the Board, or such other committee designated by the Board, shall make a recommendation to the Board as to whether to accept or reject the resignation of such incumbent director, or whether other action should be taken. The Board shall act on the resignation, taking into account the committee’s recommendation, and publicly disclose its decision regarding the resignation within 90 days following certification of the election results. If the Board accepts a director’s resignation, or if a nominee for director is not elected and the nominee is not an incumbent director, the remaining members of the Board may fill the resulting vacancy or may decrease the size of the Board.

Set forth below is information about each of our nominees for director:

Clarence L. Granger has served as our Chairman since October 2006 and has been a member of our Board of Directors since May 2002 and as our Chairman Since October 2006.2002. Mr. Granger alsoformerly served as our Chief Executive Officer from November 2002 to January 2015 and, as our Chief Operating Officer from March 1999 to November 2002,2015. Mr. Granger served as our Executive Vice President and Chief Operating Officer from January 1998 to March 1999 and as our Executive Vice President of Operations from April 1996 to January 1998. Prior to joining Ultra Clean in April 1996, he served as vice president of Media Operations for Seagate Technology, which designs, manufactures, markets and sells hard disk drives, from 1994 to 1996. Prior to that, Mr. Granger worked for HMT Technology, a supplier of high-performance thin-film disks, as chief executive officer from 1993 to 1994, as chief operating officer from 1991 to 1993 and as president from 1989 to 1994. Prior to that, Mr. Granger worked for Xidex as vice president and general manager, Thin Film Disk Division, from 1988 to 1989, as vice president, Santa Clara Oxide Disk Operations, from 1987 to 1988, as vice president, U.S. Tape Operations, from 1986 to 1987 and as director of engineering from 1983 to 1986. Mr. Granger holds a mastermaster’s of science degree in industrial engineering from Stanford University and a bachelor of science degree in industrial engineering from the University of California at Berkeley. Our Board of Directors values Mr. Granger’s perspective as our former chief executive officer and his intimate knowledge of our employee base, operations, customers, suppliers and competitive position in the semiconductor capital equipment industry.

James P. Scholhamerjoined Ultra CleanUCT as Chief Executive Officer and a member of theour Board of Directors in January 2015.Prior to joining Ultra Clean, Mr. Scholhamer served as Corporate Vice President and General Manager of Applied Materials, Inc., leading the Equipment Products Group and Display Services Group of its Global Service Division from February 2011 to January 2015. Mr. Scholhamer joined Applied Materials, Inc. in 2006, where, prior to his most recent position, he served as Vice President of Operations-Energy for the Environmental and Display Products Division from July 2006 to December 2008 and Corporate Vice President and General Manager of the Display Business Group from December 2008 to February 2011. Prior to that,

Mr. Scholhamer worked for Applied Films Corporation as Vice President of Operations, Engineering and Research Development in the company’s GermanyGerman office from September 2002 to July 2006 and as Vice President of Thin Film Coating Division and Thin Film Equipment Division in the company’s Colorado office from July 2000 to September 2002. Mr. Scholhamer holds a Bachelor of Science degree in materials and metallurgical engineering from the University of Michigan. Our Board of Directors believes that Mr. Scholhamer brings strong engineering and operations experience to our Board of Directors and will provideprovides the Board of Directors with a unique perspective as our chief executive and leader of our strategic planning process.

John Chenault has served as a director of Ultra Clean since June 2009. Mr. Chenault served as chief financial officer of Novellus Systems, a semiconductor company, from April 2005 to September 2005, at which point he retired. Prior to that, he served as vice president of Corporate Development from February 2005 to April 2005, vice president of operation and administration from September 2003 to February 2005, executive vice president of worldwide sales and service from February 2002 to September 2003 and executive vice president of business operations from July 1997 to January 2002. Mr. Chenault has also been a director and a member of the audit committee of Tessera Technologies, Inc. since March 2013 and he was a director of Synos Technology, Inc. until it was acquired by Veeco Instruments, Inc. in October 2013. Mr. Chenault holds a bachelor of business degree in economics and a masters degree in business administration from Western Illinois University. Our Board of Directors values Mr. Chenault’s extensive management and operations experience in the semiconductor industry. As a former executive officer in various capacities at one of our major customers, Mr. Chenault brings a valuable customer facing perspective to our Board of Directors. Mr. Chenault qualifies as a financial expert and chairs the Audit Committee.

David T. ibnAlehas served as a director of Ultra Clean since November 2002 and served as our lead director from February 2005 to February 2007. Mr. ibnAle has been a technology investor since 1996, and is a managing partnerFounding and Managing Partner of Reticle Equity Investors, LLC, a technology-focused investment firm. From January 2012Advance Venture Partners, LLC. He has over twenty years of experience as an investor in small andmid-sized growth companies in the technology, media and communications sectors. Prior to July 2013,co-founding AVP in 2014, Mr. ibnAle was a managing partnerManaging Partner of Augusta Columbia Capital Group from 2011 to 2013, and a technology-focused private equity firm. From March 2008 to December 2011, Mr. ibnAle was a managing directorManaging Director of TPG Growth, LLC, the small-capgrowth equity and growth investing armmiddle market investment platform of TPG, a global private equity firm. From December 1999from 2008 to March 2008, Mr. ibnAle2011. Prior to joining TPG Growth, he was an investment professional withand a Partner at Francisco Partners a technology-focused private equity firm,from 1999 to 2008, and prior to joining Francisco Partners, was an investment professional withhe began his investing career at Summit Partners L.P., a private equity and venture capital firm.Partners. Mr. ibnAle has previously served ason the chairman or as a member of the boardboards of directors of severala number of public and private technology firms, including PowerPlan, Inc., Artel, LLC, Metrologic Instruments, Inc., Mitel Networks Corp.,companies, and Electrical Components International, Inc.he currently serves on the boards of directors of Above Average Productions, Hytrust, Nativo, Unified and UrbanSitter. Mr. ibnAle holds an A.B.a B.A. in Public Policy and an A.M.a M.A. in International Development Policy from Stanford University, and a masters degree in business administrationM.B.A. from the Stanford University Graduate School of Business. Our Board of Directors values Mr. ibnAle’s experience as an investment professional, as well his experience in strategic planning and mergers and acquisitions, as he brings significant quantitative and qualitative financial experience to our Board of Directors. Mr. ibnAle qualifies as a financial expert and provides important support as a member of our Audit Committee.

Leonid Mezhvinsky has served as a director of Ultra Clean since February 2007. Mr. Mezhvinsky served as our president from June 2006 to December 2007, following our acquisition of Sieger Engineering, Inc. He has more than two decades of management experience andin-depth knowledge of machine shop, electro mechanical assemblies and system integration utilized in semiconductor, medical and biotech OEM products. Prior to joining Ultra Clean, Mr. Mezhvinsky was president and chief executive officer of Sieger Engineering, Inc. which he joined in 1982. Mr. Mezhvinsky holds the equivalent of a bachelor of science in Industrial Automation from The College of Industrial Automation, Odessa, Ukraine. Mr. Mezhvinsky brings to our Board of Directors substantial operational experience. As the former president of Sieger Engineering, which is now a part of our company,Company, he has a deep understanding of our competitors, suppliers, products and customers.

Emily M. Liggett has served as a director of Ultra Clean since May 2014. Ms. Liggett served as president and chief executive officer of NovaTorque, Inc., a manufacturer of high-efficiency electric motor systems, sincefrom 2009 anduntil late 2016, when it was acquired by Regal Beloit. She previously served as president and chief executive officer

of Apexon, Inc., a provider of supply chain optimization software solutions for global manufacturers, from 2004 to 2007. Ms. Liggett served as president and chief executive officer of Capstone Turbine Corporation (provider of microturbine systems for clean, continuous distributed energy generation) from 2002 to 2003 and, prior to that, held various management and executive roles at Raychem Corporation (acquired by Tyco International in 1999) from 1984 to 2001, including corporate vice president of Raychem and managing director of Tyco Ventures. Ms. Liggett has beenwas a director of MTS Systems Corporation sincefrom 2010 to 2016 and was a director of Immersion Corporation from 2005 to 2011. She also currently serves on the board of directors of the Purdue University School of Engineering Advisory Board. Ms. Liggett holds a bachelor of science in chemical engineering from Purdue

University, a mastersmaster’s of science in engineering and manufacturing systems from Stanford University and a mastersmaster’s degree in business administration from the Stanford University Graduate School of Business. Ms. Liggett’s qualifications to serve on our Board of Directors include her chief executive officer and management experience in a variety of technical industrial companies. She has managed worldwide businesses, partnerships, and international joint ventures. She also has public company and private company operating and board experience, and expertise in strategy, operations, new product development, sales, marketing, and business development for highly technical businesses.

Thomas T. Edman has served as a director of Ultra Clean since June 2015. Mr. Edman has served as the Chief Executive Officer of TTM Technologies, Inc. since January 2014, as its President since January 2013 and as a member of its board of directors since September 2004. From early 2011 to December 2012, Mr. Edman served as Group Vice President and General Manager of the AKT Display Business Group, which is a division of Applied Materials Inc., a publicly held provider of nanomanufacturing technology solutions. From 2006 to 2011, Mr. Edman served as Corporate Vice President of Corporate Business Development of Applied Materials, Inc. Prior to that, Mr. Edman served as President and Chief Executive Officer of Applied Films Corporation from May 1998 until Applied Materials, Inc. acquired Applied Films Corporation in July 2006. From June 1996 until May 1998, Mr. Edman served as Chief Operating Officer and Executive Vice President of Applied Films Corporation. From 1993 until joining Applied Films, Mr. Edman served as General Manager of the High Performance Materials Division of Marubeni Specialty Chemicals, Inc., a subsidiary of a major Japanese trading corporation. Mr. Edman presently serves on the board of directors of the IPC, an electronic industry association. Mr. Edman previously served as Chairman and as a member of the board of directors of FlexTech, formerly the United States Display Consortium and the AeA (American Electronics Association). Mr. Edman holds a Bachelor of Arts degree in East Asian studies (Japan) from Yale University and a Master’s degree in Business Administration from The Wharton School at the University of Pennsylvania. Mr. Edman was nominated to the board of directors because of his business acumen and experience in the technology industry, having served in numerous senior executive roles with sizeable technology companies, including as the chief executive officer of a public company. Mr. Edman also has extensive experience in Asia and with compensation-related matters.

Barbara V. Scherer has served as a director of Ultra Clean since June 2015. Ms. Scherer has served as a member of the board of directors of NETGEAR, Inc., a global networking company that delivers innovative products to consumers, businesses and service providers, since August 2011 and as a member of the board of directors of ANSYS, Inc., a publicly traded engineering simulation software and services company, since April 2013. Ms. Scherer currently is a private investor. Ms. Scherer was Senior Vice President, finance and administration and chief financial officer of Plantronics, Inc., a global leader in audio communication devices for businesses and consumers, from 1998 to 2012. In this position, she was responsible for all aspects of the company’s financial management, as well as information technology, legal and investor relations. She was Vice President, finance and administration and chief financial officer of Plantronics from 1997 to 1998. Prior to Plantronics, Ms. Scherer held various executive management positions spanning eleven years in the disk drive industry, was an associate with The Boston Consulting Group, and was a member of the corporate finance team at ARCO in Los Angeles. From 2004 through 2010, she served as a director of Keithley Instruments, Inc., a publicly traded test and measurement company, until its acquisition by Danaher Corporation. She also has experience serving on the boards ofnon-profit organizations. Ms. Scherer received B.A. degrees from the University of California at Santa Barbara and her M.B.A. from the School of Management at Yale University. With a career spanning more than 30 years including 25 in senior financial leadership roles in the technology industry, Ms. Scherer provides the Company with practical and strategic insight into complex financial reporting and management issues as well as significant operational expertise.

There are no family relationships among any of our directors and executive officers. There are no arrangements or understandings between any of our directors and us pursuant to which such director was or is to be selected as a director or nominee. Information related to the compensation of our Board of Directors can be found under “—Director Compensation” below.

Board Recommendation

Our Board of Directors recommends that you vote “FOR” each of the nominees to the Board of Directors set forth in this Proposal 1.

Structure of Board of Directors and Corporate Governance Information

Director Independence. We are required to comply with the director independence rules of the NASDAQNasdaq Stock Market (“NASDAQ”Nasdaq”) and the SEC. These rules require that the board of directors of a listed company be composed of a majority of independent directors and that the audit committee, compensation committee and nominating and corporate governance committee be composed solely of independent directors.

Our Board of Directors has determined that each of our directors and director nominees areis independent in accordance with applicable NASDAQNasdaq and SEC rules other than Messrs. Granger, Mezhvinsky and Scholhamer. Accordingly, a majority of our current Board of Directors is independent as required by NASDAQNasdaq rules and, upon election of each of our director nominees at the 20152018 Annual Meeting of Stockholders, a majority of our Board of Directors will be independent as required by NASDAQNasdaq rules.

Director Responsibilities. We are governed by our Board of Directors and its various committees that meet throughout the year. Our Board of Directors currently consists of seven directors. In accordance with our bylaws, our Board of Directors approved an increase in the size of the Board of Directors to seven directors to accommodate the appointment of our Chief Executive Officer, James P. Scholhamer, as a director in January 2015 and to eight directors in April 2015 to accommodate the election of our full slate of director nominees for the 2015 Annual meeting of Stockholders. After serving eleven terms on our Board of Directors, Susan H. Billat will not stand for reelection at the 2015 Annual Meeting of Stockholders. During 2014,2017, there were seven13 meetings of our Board of Directors. We expect directors to attend and prepare for all meetings of the Board of Directors and the meetings of the committees on which they serve. Each of our directors attended more than 75% of the aggregate number of meetings of the Board of Directors and the committees on which he or she served during 2014.2017.

Board Leadership Structure. Our corporate governance guidelines allow for the flexibility to combine or separate the offices of chairman and the chief executive officer to best serve the interests of the Company and its stockholders. In January 2015,Mr. Scholhamer serves as the chief executive officer of the Company and Mr. Granger serves as the chairman of our Chairman, retired as our Chief Executive Officer but remained as our non-executive ChairmanBoard of the Board.Directors. Our Board of Directors believes our current board leadership structure to be an efficient and successful leadership model for the Company, promoting clear accountability and effective decision-making. The roles of our Chairman and Chief Executive Officer are separated to allow Mr. Scholhamer to develop and execute on our corporate strategy and focus onday-to-day operations and company performance. Our Board of Directors believes that our stockholders benefit from Mr. Granger has conducted,Granger’s service as Chairman due to his deep background and will conductexperience in our industry and his dutiesknowledge of our operations as non-executive Chairman effectively.our former chief executive officer. Our Board of Directors recognizes that a different leadership model may be warranted under different circumstances. Accordingly, our Board of Directors periodically reviews its leadership structure.

The Board also continually reviews the need for effective independent oversight. Each member of each of our Board of Director’s standing committees is an independent director, and each independent director is actively involved in independent oversight. Our independent directors meet in executive session during each regularly scheduled quarterly meeting of our Board of Directors and periodically evaluate both our Chairman and our Chief Executive Officer. All directors have unrestricted access to management at all times and frequently communicate with the Chairman, the Chief Executive Officer and other members of management on a variety of topics. Given the above factors, our Board of Directors has historically determined that our leadership structure

was appropriate and has not deemed it necessary to appoint an independent lead director. However, our Board of Directors anticipates appointing one of our independent directors as our lead independent director following the 2015 Annual Meeting of Stockholders. is appropriate.

Corporate Governance. Our Board of Directors has adopted corporate governance guidelines. These guidelines address items such as the qualifications and responsibilities of our directors and director candidates and the corporate governance policies and standards applicable to us in general. In addition, we have adopted a code of business conduct and ethics that applies to all officers, directors and employees. Our corporate governance guidelines and our code of business conduct and ethics as well as the charters of the Nominating and Corporate Governance Committee, Audit Committee and Compensation Committee are available on our website at http://uct.com/investors/corporate-governance/.

Communicating with our Board of Directors. Any stockholder wishing to communicate with our Board of Directors may send a letter to our Secretary at 26462 Corporate Avenue, Hayward, CA 94545. Communications intended specifically fornon-employee directors should be sent to the attention of the chair of the Nominating and Corporate Governance Committee.

Annual Meeting Attendance. Our Board of Directors has adopted a policy that all members should attend each annual meeting of stockholders when practical. AllSix of our seven incumbent directors attended the 20142017 Annual Meeting of Stockholders.

Risk Oversight

Our Board of Directors plays an active role, as a whole and also at the committee level, in overseeing the management of our risks. Our Board of Directors regularly reviews reports from the management team on areas of material risk to the Company, including operational, financial, legal and strategic risks. Each of the committees of our Board of Directors also oversees the management of company risks that fall within the committee’s areas of responsibility. The Audit Committee periodically reviews risks associated with financial reporting and internal controls, as well as risks associated with liquidity, customer credit, inventory reserves and insurance coverage. The Nominating and Corporate Governance Committee assists the Board in overseeing risks associated with board organization, membership, structure and corporate governance. The Compensation Committee assists the Board in reviewing whether any material risks arise from our compensation programs and in overseeing risks associated with succession planning for our executives.

Committees of our Board of Directors

Our Board of Directors has three principal committees. The following describes each committee’s current membership, the number of meetings held during 20142017 and its mission:

Audit Committee. Among other matters, the Audit Committee:Committee is responsible for:

A copy of the Audit Committee’s charter is available on our website at http://uct.com/investors/corporate-governance/.

The current members of the Audit Committee are John ChenaultBarbara V. Scherer (chair), Susan H. BillatThomas T. Edman and David T. ibnAle. On the recommendation of the Nominating and Corporate Governance Committee of our Board of Directors, our Board of Directors expects that our Audit Committee will consist of Ms. Scherer (chair), Mr. Chenault and Mr. ibnAle following the 2015 Annual Meeting of Stockholders. Our Board of Directors has determined that each member of the committee satisfies both the SEC’s

additional independence requirement for members of audit committees and the other requirements of NASDAQNasdaq for members of audit committees. The Board of Directors has also concluded that each member of the Audit Committee qualifies as an audit committee financial expert as defined by SEC rules and has the financial sophistication required by NASDAQ.Nasdaq. The Audit Committee met five times in 2014.2017.

Compensation Committee. Among other matters, our Compensation Committee:

A copy of the Compensation Committee’s charter is available on our website at http://uct.com/investors/corporate-governance/. The Compensation Committee’s process for deliberations on executive compensation is described below under “Compensation Discussion and Analysis.”

As part of our oversight of our executive compensation program and in conjunction with the Compensation Committee, we consider the impact of our executive compensation program and the incentives created by different elements of the executive compensation program on our risk profile. In addition, we review all of our compensation policies and procedures, including the incentives that they create and factors that affect the likelihood of excessive risk taking,risk-taking, to determine whether they present a significant risk to the Company. Based on this review, we have concluded that our compensation policies and procedures are not reasonably likely to have a material adverse effect on the Company.

The current members of the Compensation Committee are Susan H. Billat (chair), John Chenault and David T. ibnAle. On the recommendation of the Nominating and Corporate Governance Committee of our Board of Directors, our Board of Directors expects that our Compensation Committee will consist of Mr. ibnAle (chair), Mr.Thomas T. Edman and Ms. Liggett following the 2015 Annual Meeting of Stockholders.Emily M. Liggett. Our Board of Directors has determined each member of the committee is independent as defined under NASDAQNasdaq and SEC rules. The Compensation Committee met six times in 2014.2017.

Nominating and Corporate Governance Committee. Among other matters, our Nominating and Corporate Governance Committee:

A copy of the Nominating and Corporate Governance Committee’s charter is available on our website at http://uct.com/investors/corporate-governance/.

The current members of the Nominating and Corporate Governance Committee are David T. ibnAle (chair), Susan H. Billat and Emily M. Liggett. On the recommendation of the Nominating and Corporate Governance Committee of our Board of Directors, our Board of Directors expects that our Nominating and Corporate Governance Committee will consist of Ms. Liggett (chair), Mr.Thomas T. Edman and Mr. ibnAle following the 2015 Annual Meeting of Stockholders.Barbara V. Scherer. Our Board of Directors has determined that each member of the Nominating and Corporate Governance Committee is independent as defined under NASDAQ.Nasdaq. The Nominating and Corporate Governance Committee met sevenfour times in 2014.2017.

Consideration of Director Nominees

Director Qualifications. The Nominating and Corporate Governance Committee of the Board operates pursuant to a written charter specifiesand establishes membership criteria for the criteria appliedBoard and each committee of the Board and recommends to director nominees. Candidatesthe Board individuals for membership on the Board and its committees. There is no fixed set of qualifications that must be satisfied before a candidate will be considered. Rather, candidates for director nominees are reviewed in the context of the current composition of our Board of Directors, our operating requirements and the interests of our stockholders. In conducting its assessment, the committee considers issues of judgment, diversity, age, skills, background, experience and such other factors as it deems appropriate given the needs of the Company and our Board of Directors. Although we do not have a formal policy with regard to the consideration of diversity, when identifying and selecting director nominees, the Nominating and Corporate Governance Committee also considers the impact a nominee would have in terms of increasing the diversity of our Board of Directors with respect to professional experience, skills, backgrounds, viewpoints and areas of expertise. The Nominating and Corporate Governance Committee also considers the independence, financial literacy and financial expertise standards required by our committee charters and applicable laws, rules and regulations, and the ability of the candidate to devote the time and attention necessary to serve as a director and a committee member.

Identifying and Evaluating Nominees for Director. In the event that vacancies are anticipated or otherwise arise, the Nominating and Corporate Governance Committee (or, if the Nominating and Corporate Governance Committee is not comprised solely of independent directors, our independent directors) considers various potential candidates for director. Candidates may come to the attention of the Nominating and Corporate Governance Committee (or our independent directors) through current directors, professional search firms engaged by us, stockholders or other persons. Candidates are evaluated at regular or special meetings of the Nominating and Corporate Governance Committee (or our independent directors) and may be considered at any point during the year.

Stockholder Nominees. Candidates for director recommended by stockholders will be considered by the Nominating and Corporate Governance Committee (or our independent directors). Such recommendations should include the candidate’s name, home and business contact information, detailed biographical data, relevant qualifications for membership on our Board of Directors, information regarding any relationships between the candidate and our Company within the last three years and a written indication by the recommended candidate of the candidate’s willingness to serve on our Board of Directors. Stockholder recommendations, with such accompanying information, should be sent to the attention of the Chair of the Nominating and Corporate Governance Committee at the address listed under “Information Concerning Solicitation and Voting—Contacting Ultra Clean.”

Stockholders also may nominate directors for election at our annual meeting of stockholders by following the provisions set forth in our bylaws.Amended and Restated Bylaws. The deadline and procedures for stockholder nominations are disclosed elsewhere in this proxy statement under the caption “Information Concerning Solicitation and Voting—Deadline for Receipt of Stockholder Proposals.”

Director Compensation

For fiscal 2014,2017, eachnon-employee director was paid a $35,000$50,000 annual cash retainer fee, as well as, if applicable, a $12,000 annual cash fee for serving on the Audit Committee, a $7,500 annual cash fee for serving

on the Compensation Committee, a $5,000 annual cash fee per committee for serving on the Compensation and the Nominating and Corporate Governance Committees,Committee, a $20,000 annual cash fee for serving as

chair of the Audit Committee (which includes the fee to serve on the Audit Committee) andsuch committee), a $10,000$15,000 annual cash fee for serving as chair of the Compensation and Nominating and Corporate Governance CommitteesCommittee (which includes the fee to serve on eachsuch committee). In fiscal 2014,, a $10,000 annual cash fee for serving as chair of the Nominating and Corporate Governance Committee (which includes the fee to serve on such committee), and a $30,000 annual cash fee for serving as Chairman of the Board. On the date of our 2017 annual meeting of stockholders, eachnon-employee director was granted 8,000a restricted stock unitsaward for 7,500 shares of our common stock that fully vestvests on the earlier of (i) the day before the 20152018 Annual Meeting of Stockholders and (ii) May 21, 2015.24, 2018.

In February 2015, the Board of Directors approved that, for fiscal 2015, each non-employee director would receive a cash retainer and equity award consistent with that received for fiscal 2014, to be paid/granted at the date of the 2015 Annual Meeting of Stockholders. Annual fees for serving on the Board of Directors and on or as chair of committees were not changed. In addition, the Board determined that the Company will continue to pay the lease amount and insurance premiums due on the Company car Mr. Granger used as our Chief Executive Officer, from his retirement date through the 2015 Annual Meeting of Stockholders.

The following table sets forth compensation for ournon-employee directors for fiscal 2014:2017:

Mr. Granger is not included in the table above because he received no separate compensation for services as a director during 2014. Mr. Granger retired as our Chief Executive Officer in January 2015 but remains as the Chairman of our Board of Directors. His compensation is set forth under “Executive Officer Compensation—Summary Compensation Table.” Mr. Scholhamer became a member of our Board of Directors in January 2015 and does not receive separate compensation for services as a director.

Director Stock Ownership Guidelines; Policy against Hedging Transactions and Pledges

The Board of Directors has adopted stock ownership guidelines for our directors to more closely align the interests of our directors with those of our stockholders. The guidelines provide that each director should hold at least 10,000 shares of our common stock, and that each director be allowed three years from the date such director joined our Board of Directors to accumulate such number of shares of our common stock. All of our directors are currently meetin compliance with our stock ownership guidelines.

The Company’s Insider Trading Policy, which can be found on our website, provides that shares of Ultra Clean stockour securities shall not be made subject to a hedge transactiontransactions or puts and calls. The Insider Trading Policy further prohibits any pledges of shares of Ultra Clean stockour securities by our directors and executive officers.

Payments to Compensation Consultant and its Affiliates

In April 2016, the Compensation Committee determined to engage Radford (“Radford”), a part of Aon plc, with respect to fiscal 2017 executive officer andnon-employee director compensation matters. Radford was retained by our Compensation Committee to provide an independent review of the Company’s executive compensation programs, including an analysis of both the competitive market and the design of the programs for

2017. In addition, during 2017, Radford assisted the Compensation Committee with its evaluation of the risks associated with our compensation programs and provided our Compensation Committee with a director compensation assessment and assistance in developing our Compensation Discussion and Analysis in this proxy statement. Radford also furnished the Compensation Committee with reports on peer company practices relating to the following matters: short-term and long-term compensation program design; equity compensation; retention value of current equity holdings; target incentive opportunities; and compensation trends for board and committee members. We incurred $34,000 and $60,000 in fees for Radford’s work in fiscal years 2016 and 2017, respectively. For further discussion of the work conducted by Radford as our compensation consultant, see “Compensation Discussion and Analysis—Process for Determining Executive Compensation.”

Certain Relationships and Related Party Transactions

Transactions with Directors. The Company leases a facility from an entity controlled by Leonid Mezhvinsky, one of our directors. In the year ended December 26, 2014,29, 2017, we incurred rent and other expenses resulting from the lease of this facility of approximately $297,000.$322,000.

Related Person Transaction Policy. Our written Related Person Transaction Policy requires our Board of Directors or the Nominating and Corporate Governance Committee to review and approve all related person transactions. Our directors and officers are required to promptly notify our Chief Compliance Officer (which is currently the Chief Financial Officer) of any transaction which potentially involves a related person. Our Board of Directors or the Nominating and Corporate Governance Committee then considers all relevant facts and circumstances, including without limitation the commercial reasonableness of the terms of the transaction, the benefit and perceived benefit, or lack thereof, to the Company, opportunity costs of alternate transactions, the materiality and character of the related person’s direct or indirect interest, and the actual or apparent conflict of interest of the related person. Our Board of Directors or the Nominating and Corporate Governance Committee will not approve or ratify a related person transaction unless it has determined that, upon consideration of all relevant information, the transaction is in, or not inconsistent with, the best interests of the Company and its stockholders.

PROPOSAL 2: RATIFICATION OF THE APPOINTMENT OF OUR

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Audit Committee has appointed Moss Adams LLP (“Moss Adams”) to serve as our independent registered public accounting firm for fiscal 2015.2018. We are asking you to ratify this appointment. Ratification of the appointment although yourof Moss Adams as our independent registered public accounting firm for fiscal 2018 requires the affirmative vote of the holders of a majority of our common stock present in person or represented by proxy at the annual meeting and entitled to vote thereon. Abstentions will have the same effect as negative votes for this proposal. Although ratification is not required. Inrequired for us to retain Moss Adams, in the event of a majority vote against ratification, the Audit Committee may reconsider its selection. Even if the appointment is ratified, the Audit Committee may, in its discretion, direct the appointment of a different independent registered public accounting firm at any time during the year if the Audit Committee determines that such a change would be in the Company’s and its stockholders’ best interests. A representative of each of Deloitte & Touche LLP and Moss Adams is expected to be present at the annual meeting of stockholders, will have the opportunity to make a statement if he/she desires to do so and is expected to be available to respond to appropriate questions.

Dismissal of Deloitte & Touche LLP (“Deloitte)

During fiscal 2014, Deloitte served as our independent auditors and also provided tax services. On March 30, 2015, we dismissed Deloitte as our independent registered public accountant.

The report of Deloitte on our consolidated financial statements for the fiscal years ended December 26, 2014 and December 27, 2013 did not contain any adverse opinion or disclaimer of opinion, and was not qualified or modified as to uncertainty, audit scope or accounting principles.

As it relates to the fiscal years ended December 26, 2014 and December 27, 2013, and through March 30, 2015, the effective date of Deloitte’s dismissal, (i) there were no disagreements (as that term is defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions) between the company and Deloitte on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which, if not resolved to the satisfaction of Deloitte would have caused Deloitte to make reference to the subject matter of the disagreement in connection with its report, and (ii) there were no “reportable events” (as that term is defined in Item 304(a)(1)(v) of Regulation S-K).

A representative of Deloitte & Touche LLP is expected to be present at the annual meeting of stockholders, will have the opportunity to make a statement if he/she desires to do so and is expected to be available to respond to appropriate questions.

Appointment of Independent Registered Public Accounting Firm Moss Adams LLP (“Moss Adams”)

On April 1, 2015, we appointed Moss Adams as the company’s independent registered public accounting firm to perform independent audit services beginning with fiscal year 2015. Through April 1, 2015, neither the company, nor anyone on its behalf, consulted Moss Adams regarding either (i) the application of accounting principles to a specified transaction, either completed or proposed, or the type of audit opinion that might be rendered with respect to our consolidated financial statements, in any case where a written report or oral advice was provided to the company by Moss Adams that Moss Adams concluded was an important factor considered by the company in reaching a decision as to any accounting, auditing or financial reporting issue; or (ii) any matter that was the subject of a disagreement (as that term is defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions) or a “reportable event” (as that term is defined in Item 304(a)(1)(v) of Regulation S-K).

A representative of Moss Adams is expected to be present at the annual meeting of stockholders, will have the opportunity to make a statement if he/she desires to do so and is expected to be available to respond to appropriate questions.

Audit Fees and Tax Fees

Set forth below are the aggregate audit fees incurred for the professional services provided by our independent registered public accounting firm, Deloitte & Touche LLP, the member firms of Deloitte Touche Tohmatsu Limited,Moss Adams and their respectiveits affiliates (collectively, “Deloitte & Touche”), in fiscal 20142017 and 2013.fiscal 2016.

Audit fees consist of fees billed, or to be billed, for services rendered to us and our subsidiaries for the audit of our annual financial statements and internal control over financial reporting, reviews of our quarterly financial statements included in our quarterly reports on Form10-Q and audit services provided in connection with other statutory and regulatory filings.

Tax fees consist of fees billed for professional services for assistance regarding worldwide transfer pricing analysis and documentation.

Preapproval Policy of Audit Committee of Services Performed by Independent Auditors

The Audit Committee’s policy requires that the committee preapprove audit andnon-audit services to be provided by our independent auditors before the auditors are engaged to render services. The Audit Committee may delegate its authority topre-approve services to one or more Audit Committee members; provided that such designees present any such approvals to the full Audit Committee at the next Audit Committee meeting.

All services described above werepre-approved in accordance with the Audit Committee’spre-approval policies.

Board Recommendation

Our Board of Directors recommends that you vote “FOR” ratification of the appointment of Moss Adams LLP as our independent registered public accounting firm for fiscal 2015.2018.

REPORT OF THE AUDIT COMMITTEE

REPORT OF THE AUDIT COMMITTEE OF THE BOARD OF DIRECTORS

The following ReportNotwithstanding any statement to the contrary in any of our previous or future filings with the Securities and Exchange Commission, this report of the Audit Committee of theour Board of Directors shall not be deemed to be “soliciting material” or to be “filed” with the SEC norSecurities and Exchange Commission or “soliciting material” under the Securities Exchange Act of 1934, as amended, and shall this informationnot be incorporated by reference into any future filing under the Securities Act of 1933 (the “Securities Act”) or the Securities Exchange Act of 1934 (the “Exchange Act”), each as amended, except to the extent that Ultra Clean specifically incorporates it by reference into such filing.filings.

The Audit Committee, serves in an oversight capacitywhich currently consists of Barbara V. Scherer, Thomas T. Edman and is not intended to be part of our operational or managerial decision-making process. Our management is responsible for preparing our consolidated financial statements, andDavid T. ibnAle, evaluates audit performance, manages relations with our independent registered public accounting firm is responsible for auditing those statements. The Audit Committee’s principal purpose isand evaluates policies and procedures relating to monitor these processes.

The Audit Committee is currently composed of three directors, each of whom meets the requirements of applicable NASDAQ Stock Marketinternal accounting functions and Securities and Exchange Commission rules for audit committee independence.controls. The key responsibilities of our Audit Committee are set forth in our Audit Committee’s charter, which is available on our website athttp://uct.com/investors/corporate-governance/. This report relates to the activities undertaken by the Audit Committee in fulfilling such responsibilities.

The Audit Committee regularly metmembers are not professional auditors, and held discussions withtheir functions are not intended to duplicate or to certify the activities of management and our independent registered public accounting firm in 2014. Management represented to the Audit Committee that Ultra Clean’s consolidated financial statements were prepared in accordance with generally accepted accounting principles applied on a consistent basis, and the Audit Committee has reviewed and discussed the quarterly and annual earnings press releases and audited consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 26, 2014 with management and our independent registered public accounting firm. The Audit Committee oversees our financial reporting process on behalf of our Board of Directors. Our management has the primary responsibility for the financial statements and reporting process, including our systems of internal controls over financial reporting. In fulfilling its oversight responsibilities, the Audit Committee reviewed and discussed with management the audited financial statements included in the Annual Report on Form10-K for the year ended December 29, 2017. This review included a discussion of the quality and the acceptability of our financial reporting and internal control over financial reporting, including the clarity of disclosures in the financial statements.

The Audit Committee also discussedreviewed with our independent registered public accounting firm, who is responsible for expressing an opinion on the conformity of our audited financial statements with generally accepted accounting principles, their judgments as to the quality and the acceptability of our financial reporting and such other matters required to be discussed bywith the statement onAudit Committee under generally accepted auditing standards in the United States including Auditing StandardsStandard No. 16,Communications with Audit Committees, as amended, issuedadopted by the Public Company Accounting Oversight Board (PCAOB)(the “PCAOB”).

The Audit Committee has discussed with ourreceived the written disclosures and the letter from the independent registered public accounting firm its independence from us and our management, including the matters, if any, in the written disclosures pursuant torequired by applicable requirements of the Public Company Accounting Oversight BoardPCAOB regarding anthe independent accountant’s communications with the Audit Committee concerning independence. The Audit Committee also considered whetherdiscussed with the independent registered public accounting firm such auditors’ independence from management and Ultra Clean, including the matters in such written disclosures required by applicable requirements of the PCAOB regarding the independent accountant’s communications with the Audit Committee concerning independence.

The Audit Committee further discussed with our independent registered public accounting firm’s provision of audit and non-audit services to us is compatible with maintaining the independence of our independent registered public accounting firm from us.

The Audit Committee discussed with our internal and independent auditors the overall scope and plans for their respective audits. The CompensationAudit Committee meets periodically with the internal and independent auditors,registered public accounting firm, with and without management present, to discuss any significant matters regarding internal control over financial reporting that have come to their attention during the results of their examinations, their evaluations of our internal controlsaudit, and to discuss the overall quality of our financial reporting. To avoid certain potential conflicts of interest, the law prohibits a publicly traded company from obtaining certain non-audit services from its independent audit firm. We obtain these services from other service providers as needed.

BasedIn reliance on the reviews and discussions referred to above, the Audit Committee recommended to our Board of Directors and our Board of Directors approved that the audited consolidated financial statements and disclosures under “Management’s Discussion and Analysis of Financial Condition and Results of Operations” be included in ourthe Annual Report on Form10-K for the year ended December 26, 2014, for filing29, 2017, as filed with the Securities and Exchange Commission.Commission on March 14, 2018.

The Audit Committee has appointed Moss Adams LLP as our independent auditors for 2015.

Members of the Audit Committee

John Chenault,Barbara V. Scherer, Chair

Susan H. BillatThomas T. Edman

David T. ibnAle

PROPOSAL 3: ADVISORY VOTE APPROVING THE COMPENSATION OF THE NAMED EXECUTIVE OFFICERS

This proposal provides you with an opportunity to cast anon-binding, advisory vote approving the fiscal 20142017 compensation of our named executive officers as disclosed pursuant to the compensation disclosure rules of the SEC in this proxy statement, including the “Compensation Discussion and Analysis,” the compensation tables and other narrative executive compensation disclosures. Consistent with the non-binding advisory voteAt our 2017 Annual Meeting of our stockholders at our 2011 annual meeting,Stockholders, we willadopted a proposal to hold anon-binding, advisory vote on executive compensation annually and are required to do so until our nextnon-binding, advisory vote on the frequency of stockholder advisory votes on executive compensation, which is required to occur no later than our 20172023 Annual Meeting of Stockholders. Although, as an advisory vote, this proposal is not binding on us or our Board of Directors, the Compensation Committee and our Board of Directors value the opinions of the stockholders and will consider the outcome of the vote when making future compensation decisions.

As described in detail under the heading “Compensation Discussion and Analysis,” our executive compensation programs are designed to attract, motivate and retain our named executive officers, who are critical to our success. Under these programs, our named executive officers are rewarded for the achievement of specific short-term and long-term goals. We believe our 20142017 executive compensation is appropriate. Please see the “Compensation Discussion and Analysis” beginning on page 2018 for additional details about our executive compensation philosophy and programs, including information about the fiscal 20142017 compensation of our named executive officers. This advisory vote is not intended to address any specific item of compensation, but rather the overall compensation principles and practices and the fiscal 20142017 compensation of our named executive officers.

The affirmative vote of a majority of the shares of common stock present in person or represented by proxy and entitled to vote on this item will be required to approve, byAs an advisory vote, this proposal is not binding on us or our Board of Directors. The Compensation Committee and our Board of Directors value the opinions of the stockholders and will consider the outcome of the vote when making future compensation of our named executive officers. Abstentions will have the same effect as negative votes for this proposal.decisions.

Board Recommendation

Our Board of Directors recommends that you vote “FOR” the approval of the compensation of the named executive officers for fiscal 20142017 as disclosed pursuant to the compensation disclosure rules of the SEC, which disclosure includes the “Compensation Discussion and Analysis,” the compensation tables and other narrative executive compensation disclosures in this proxy statement.

EXECUTIVE OFFICER COMPENSATION

Compensation Discussion and Analysis

The Compensation Discussion and Analysis, or CD&A, describes and analyzes our executive compensation philosophy and program in the context of the compensation paid during 2017, the last fiscal year, to our chief executive officer, our chief financial officer, and each of our three other highest paid executive officers (collectively referred to as our named executive officers). Our named executive officers for fiscal 2017 are:

Biographical information regarding these officers is set forth in our Annual Report on Form10-K filed with the SEC on March 14, 2018. Mr. Scholhamer’s biography is also set forth above with our other directors.

Fiscal 2017 Key Financial and Share Performance Highlights

As a general principle, it is the Company’s goal to tie the Company’s performance closely with executive compensation. Therefore, in order to provide proper context regarding the Company’s compensation practices and their correlation to the Company’s overall performance, the table below provides a summary of the Company’s financial and share performance for fiscal year 2017.

These financial highlights demonstrate significant improvements in the Company’s performance for 2017. As a result, we believe that the compensation paid to our named executive officers in 2017 as described below was aligned with the Company’s significantly improving performance.

Overview of Compensation Program and Philosophy

Our compensation program, which is established by our Compensation Committee, is intended to meet three principal long-term objectives:

To meet these objectives, we have historically adopted the following overriding long-term compensation policies:

Our Compensation Committee considers these policies in determining the appropriate allocation of long-term compensation, base salaries, annual bonuscash incentive compensation, long-term equity-based compensation and other benefits. Other considerations include our business objectives and environment, fiduciary and corporate responsibilities (including internal equity considerations and affordability), competitive practices and trends, regulatory requirements, and regulatory requirements.the mitigation of risks associated with these policies. Like most companies, we use a combination of fixed and variable compensation programs to reward and incentivize strong performance, as well as to align the interests of our executive officers with those of our stockholders. In determining the particular elements of compensation that will be used to implement our overall compensation policies, the Compensation Committee takes into consideration a number of factors related to corporate performance, as further described below, as well as competitive practices among our peer groupgroup.

In 2017, after comparing the revenue, profitability, operating income, market capitalization and certain other metrics of our Company relative to other members of the practices2017 Peer Group (described below), our compensation committee determined to revise its long-term compensation philosophy to generally target, on a long-term basis, compensation at the 50th percentile of comparable companies for each element of our compensation program. Our long-term goal in prior years was to target total compensation, including base salaries, cash incentive awards and equity awards near the 50th percentile among similar companies, noted in industry surveys.

Fiscal 2014 Key Considerations

Similar to fiscal 2014,of which total cash compensation (including base pay and as discussed further below under “—Process for Determining Executive Compensation,” we did not benchmarkannual cash incentives) was targeted between the compensation25th and 50th percentile of our named executive officers for fiscal 2014 on an executive-by-executive basis against our peer group. In addition, the Compensation Committee determined not to engage an independent compensation consultant to review the competitivenesssuch companies, and structure of the Company’s 2014 cashtime and equity incentive programs or to provide the Compensation Committee with recommendations regarding changes to such plans in connection with the Compensation Committee’s decisions on executive compensation for fiscal 2014. In making this determination, the Compensation Committee considered that it engaged an independent compensation consultant for such purpose in 2013. Moreover, the Compensation Committee utilized data from industry surveys on executive compensation to assist it in its determination of executive compensation for fiscal 2014.

Our fiscal 2014 compensation decisions, on an aggregate basis, primarily reflected the state of our business (and in particular, the state of the semiconductor industry), our share price, the state of the global economy and the demand for our products in the industries we served during fiscal 2014. Our sales were $514.0 million for fiscal 2014, representing an increase of 15.8% compared to $444.0 million in sales for fiscal 2013. Our gross profit also improved in fiscal 2014 as compared to fiscal 2013, as did our stock price, which, at the time of the

Compensation Committee’s compensation deliberations for 2014 executive compensation, was approximately 85% higher than the Company’s average stock price in 2013. Overall, our Compensation Committee believes that our results and stock price for fiscal 2014 reflect an improvement in overall business conditions, particularly in the semiconductor industry, from 2013 and from the recent, extended period of depressed demand and uncertainty. Based on the above, and as reflected in the “Summary Compensation Table” below, our Compensation Committee determined to increase fiscal 2014 compensation for our named executive officers as compared to fiscal 2013.

On an individual basis, our fiscal 2014 compensation decisions primarily reflected the importance of our top executives (i.e., our chief executive officer, our executive vice president and chief financial officer and our senior vice president of Asia) to our business and their roles in the improvement in the Company’s operating and stock price performance during fiscal 2014. The Compensation Committee considers these executives, particularly our chief executive officer and executive vice president and chief financial officer, to be primarily responsible for the improvement in our overall performance. Moreover, the Compensation Committee recognized that these executives were our primary strategic decision makers during fiscal 2014.

Consistent with prior years, each of our named executive officers were eligible for increased cash incentive compensation and earned performance-based equity awards based on our resultshistorically was targeted between the 50th and 75th percentile among such companies. We believe that targeting overall, and each element of, operations, thus tying compensation very closely with our performance. Theat the 50th percentile will enable us to remain competitive in attracting and retaining qualified executive officers while avoiding paying amounts in excess of what we believe is necessary to attract and retain such executive officers. Our Compensation Committee also considers thatretains the valuediscretion to our executive officerstarget compensation for specific individuals based on a variety of their long-term equity incentive awards increases with our stock price, providing our executives with further opportunity to increase the value of the compensation they ultimately realize, while aligning their incentives more closely with stockholder value.additional factors, including Company and individual performance.

Stockholder Votes

At our 2014 annual meeting of stockholders, the stockholders approved our non-binding advisory vote on our fiscal 2013 executive compensation program (“say-on-pay”). After considering our say-on-pay voting results and other factors addressed in the subsequent discussion, the Compensation Committee determined not to make changes to our executive compensation policies and practices as a result of the vote. At our fiscal 2011 annual meeting of stockholders, a majority of the stockholders voted to have the non-binding say-on-pay advisory vote appear annually in our proxy statement. Our Board of Directors considered the results of the vote and agreed with the results. Therefore, we are including the non-binding say-on-pay advisory vote on our executive compensation in this year’s proxy, and will have annual votes at least until the next stockholder vote on frequency. Executive compensation decisions for fiscal 2014 and other details are discussed below in this compensation discussion and analysis.

Process for Determining Executive Compensation

Each year, our Compensation Committee, together with our senior management team, establishes performance targets for short-term and long-term incentive plans that require the achievement of significant financial results. Each year, our Compensation Committee determines compensation by assessing prior year performance against these established financial targets, as well as other factors such as the compensation paid by comparable companies (which may include comparisons to companies in broad-based compensation surveys or, for fiscal 2017, our 2017 Peer Group), achievement of strategic objectives, improvements in market share and the professional development and potential of individual officers. Ultimately, the amount of compensation awarded to our executive officers is determined based on performance and what our Compensation Committee believes is in the best interests of our stockholders.

The Compensation Committee meets with our chief executive officer who was Mr. Granger in fiscal 2014, and other executives, including our senior vice president of human resources, as necessary, to obtain recommendations with respect to Company compensation programs, practices and packages. The chief executive officer, in consultation with our senior vice president of human resources, develops recommendations that he makes recommendations to the Compensation Committee on executive performance, base salary, annual bonus targets and equity compensation for the executive team and other employees, other than himself. Our senior vice president of human resources also meets directly with the Compensation Committee (including outside the presence of our chief executive officer) to assist the Compensation Committee in its decision-making process, including its analysis of broad-based data from third-party industry surveys and other data on executive compensation. Although the Compensation Committee considers management’s recommendations with respect to executive compensation, the Compensation Committee makes all final decisions on executive compensation matters.

TheOur chief executive officer attendsand senior vice president of human resources attend most of the Compensation Committee’s meetings, but the Compensation Committee also holds executive sessions not attended by any members of management ornon-independent directors. The Compensation Committee deliberates and makes decisions with respect to performance and compensation without the chief executive officer and the Company’s other executives present. The Compensation Committee has the ultimate authority to make decisions with respect to the compensation of our executive officers, but may, if it chooses, delegate some of its responsibilities to subcommittees. The

Compensation Committee has not in the past delegated authority with respect to the compensation of executive officers. The Compensation Committee has delegated to the chief executive officer the authority to grant equity awards to employees below the level of corporate vice president under guidelines approved by the Compensation Committee and to make salary adjustments and short-term bonus decisions for employees (other than executive officers) under guidelines approved by the Compensation Committee.

The Compensation Committee also periodically seeks input fromengaged Radford as its outside compensation consultant in April 2016 to provide an independent compensation consultants prior to making determinations onreview the Company’s executive compensation though no suchprogram and recommend a course of action for fiscal year 2017, including an analysis of both the competitive market and the design of our compensation programs. More specifically, Radford advised the Compensation Committee on the designation of peer group companies, evaluated the final list of peer companies approved by the Compensation Committee and provided competitive compensation data and analysis relating to the compensation of our chief executive officer and our other executive officers. Radford also furnished the Compensation Committee with reports on peer company practices relating to the following matters: short-term and long-term compensation program design; equity compensation; retention value of current equity holdings; target incentive opportunities; and compensation trends for board and committee members. In addition, the Compensation Consultant assisted the Compensation Committee with its evaluation of the risks associated with our compensation programs and provided our Compensation Committee with an assessment of our directors’ compensation. Radford attended meetings of the Compensation Committee regarding executive compensation and also communicated with the chair of the Compensation Committee outside of meetings. The consultant was engagedreported to the Committee rather than to management, although the consultant met with management from time to time for such purpose with respectpurposes of gathering information on proposals that management made or may make to fiscal 2014 compensation.the Compensation Committee. The Compensation Committee has the sole authority to retainreplace the compensation consultant or hire additional consultants at any time.

Radford provides analyses and terminaterecommendations that inform the Compensation Committee’s decisions, but it does not decide or approve any compensation decisions. Except for the Company’s subscription to certain broad-based compensation survey data, Radford has not provided any services to the Company other than to the Compensation Committee and receives compensation from the Company only for services provided to the Compensation Committee. Our Compensation Committee assessed the independence of Radford pursuant to SEC and NASDAQ rules and concluded that Radford is independent legal, financial, accounting or other advisors as it determines necessaryand that Radford’s work has not raised any conflict of interest. For a discussion of amounts paid to carry out its duties, without conferring with or obtaining the approval of management or the full Board of Directors, including the sole authority to approve the feesRadford for executive and director compensation consulting and other retention terms of any such firm. Theservices, please see “Payments to Compensation Committee also utilizes data from industry surveys on executive compensation to assist it inConsultant and its determination of executive compensation.Affiliates” above.

Elements of Compensation Structure

The following are the primary elements of our executive compensation program:

Pay Mix.We have selected thesethe foregoing compensation elements because each is considered useful and/or necessary to meet one or more of the principal objectives of our compensation policy. For example, base salary and bonuscash incentive target percentages are set with the goal of attracting employees and adequately compensating and rewarding them for their individual performance, level of responsibility, time spent with the Companyexperience and the Company’s annual financial results, while our equity compensation programs are geared toward providing incentivelong-term incentives and rewardrewards for the achievement of long-term business objectives and retaining key talent. We believe that these elements of compensation, when combined, are effective, and will continue to be effective, in achieving the objectives of our compensation program.

The Compensation Committee reviews base salary, cash incentive programs and long-term incentive programs on at least an annual basis. Other programs are reviewed from time to time to ensure that benefit levels remain competitive but are not included in the annual determination of an executive’s compensation package. In setting compensation levels for a particular executive, the Compensation Committee takes into consideration the proposed compensation package as a whole and each element individually, as well as the executive’s past and expected future contributions to our business.

Although we did not benchmark our executive compensation for fiscal 2014 against our peer group, our long-term goal has been to target total compensation, including base salaries, cash incentive awards and equity awards near the 50th percentile among our peer group. To achieve this, our goal has been to allocate total compensation such that cash compensation (including base pay and annual bonus) falls between the 25th and 50th percentile among the peer group, and time and performance based equity awards, which provide our executives with long-term incentives, fall between the 50th and 75th percentile of the peer group, consistent with our pay-for-performance objectives and focusing on creation of long-term stockholder value. Notwithstanding these long-term compensation objectives, theOur Compensation Committee considers uncertaintybelieves that the particular elements of compensation identified above produce a well-balanced mix of both fixed andat-risk compensation that collectively promote retention value and provide each executive officer with both short-term and long-term performance incentives. Base pay provides the executive officer with a measure of security as to the minimum level of compensation he or she will receive while the annual and long-term incentive components motivate the executive officer to focus on the business metrics that will maximize company performance over the long term. Our Compensation Committee believes that this approach will yield increases in the macro-economy and cyclicality in the industries we serve, among other factors, in determining compensation packagesstockholder value, provide an appropriate reward for our executive officers, and reduce the risk of loss of executive officers to competitors.

While each element of our compensation program is intended to motivate and encourage employees at all levels to drive performance and achieve superior results for our stockholders, each element is weighted differently for each of our named executive officers based on the employee’s position and ability to impact our financial results. In general, the percentage of performance-based pay, orat-risk pay, increases with job responsibility. This balance is intended to offer an opportunity for gain in recent years, these considerations have resulted inthe event of successful performance, matched with the prospect of less compensation that our Compensation Committee believed werewhen performance falls short of established financial and/or stockholder return targets. The table below our long-term target percentiles within our peer group. In

addition,depicts the Compensation Committee has considered our stock price, which was relatively depressed in recent years, in determining to grant equity incentive awards that the Compensation Committee believed werelower-than-market in termsallocation of value in fiscal years 2012 and 2013, so as to avoid excess dilution and conserve the number of shares available for future grant under our stock incentive plan. At the time our Compensation Committee determined fiscal 2014 executive compensation, our stock price was significantly higher than our stock pricefixed versus “at risk” pay for the corresponding period in fiscal 2013, contributing to the increase in the grant date fair value of our equity awards tototal target compensation for our named executive officers in 2017:

In fiscal 2014,2017, consistent with recent years, we granted our named executive officers a combination of time-based and performance-based restricted stock units, or RSUs, which we believe are effective in retaining and motivating employees because they provide a predictable, tangible value to employees while also serving as an incentive to increase the value of our stock. RSUs are also an efficient way for us to reduce the dilutive effects of equity awards. We grant both time-based and performance-based RSUs to our executive officers. The Compensation Committee believes this combination provides a balance between awards that provide high incentive value (in the form of performance-based RSUs,PSUs, which will only vest if we meet performance criteria described under “—Mix of Performance versus Time-based ‘Refresh’ Grants” below, combined with service requirements) and awards that provide high retention value (in the form of time-based RSUs, which will have at least some value over time while imposing continued service requirements, and requiring time-based vesting of the earned performance units). In April of 2017, the Compensation Committee granted the following long-term equity awards to our named executive officers:

The number of equity awards the Compensation Committee granted to each executive officer in fiscal 2014April 2017 was determined based on a variety of factors. In deciding the awards for fiscal 2014, the Compensation Committee (in consultation with Mr. Granger) consideredfactors, including each individual executive’s job performance but primarilyand his or her level of job responsibility. The Compensation Committee also considered that we had seen some continued recovery in overall business conditions and an improved stock price from our average stock price over fiscal 2013 and 2012. Mr. Granger and the Compensation Committee discussed the use of long-term equity awards as a means to retain and incentivize executivesexecutives. The number of equity awards granted is also influenced by our stock price at the time the awards are granted, as well as our long-term, overall compensation targets. Following such discussion, the Compensation Committee decided to grant additional long-term equity awards to named executives officers as follows:new hires and promotions.

The number and target value of RSUs granted to Messrs. Granger, Eichler and Lev increasedMr. Scholhamer in fiscal 20142017 was set at a target value of $1.5 million as comparedpart of the Compensation Committee’s long-term goal of better aligning our chief executive officer’s equity awards with market levels, and also to recognize Mr. Scholhamer’s strong performance and significant contributions to our organization. The dollar value of Ms. Savage’s RSUs granted in April 2017 was set at a value lower than fiscal 2013, primarily2016 due to the fact that Ms. Savage had received a significant promotional grant of RSUs in fiscal 2016 when she was promoted to our chief financial officer. The Compensation Committee’s recognitionCommittee also considered its long-term goal of setting grants at a level consistent with the market 50^th percentile of our peer group in determining grants for ournon-CEO named executive officers for fiscal 2017, while at the same time considering the relative positions of each such officer’s rolenamed executive officer within our global organization and past grant practices. The 2017 equity awards granted in the improvement in our operating results and stock price during fiscal 2013, the significance of their roles in our overall managementApril 2017 for fiscal 2014, and the Compensation Committee’s determination of the correlation of their responsibilities with our overall corporate operating performance, as well as their anticipated increased responsibilities given the departure of our former President and Chief Operating Officer announced in February of 2014. The grant date fair value of fiscal 2014 RSUs granted to our named executive officers also increased as compared to fiscal 2013 grants, primarily due to the increaseshow in the numbertable above were all generally within targeted levels, as adjusted to maintain internal equity for named executive officers with similar levels of grants as described above, as well asresponsibility within our increased stock price.Company.

Following the Compensation Committee’s April 2017 meeting, the Compensation Committee subsequently determined to make the following additional awards of RSUs in fiscal 2017:

The additional grants to Ms. Savage and Mr. Lev shown in the table above where made in July and August of 2017, respectively, in connection with their additional responsibilities during our CEO’s leave of absence discussed above. The additional grant to Mr. Williams was made in July 2017 and was recommended to our Compensation Committee by our chief executive officer to recognize Mr. Williams outstanding performance in fiscal 2017 against his personal goals and key performance indicators.

The equity awards granted during fiscal 20142017 to our named executive officers are set forth in detail under “Grants of Plan-Based Awards” below. All time-based RSUs granted to our named executive officers in fiscal 2014,2017, and all performance-based RSUsPSUs earned based on fiscal 20142017 performance, vest over a period of 3 years from the grant date in equal annual installments.

Promotional and New Hire Grants. The Compensation Committee’s policy has been to make promotional grants on solely a time-based vesting schedule to enhance retention.

Mix of Performance versus Time-based “Refresh” Grants.The mix of time-based and performance-based awards for grants made in April of 2017 described above was consistent with prior years. In allocating equity awards between time-based and performance-based awards, the Compensation Committee consideredconsiders each named executive officer’s level of responsibility, and the relationship between that named executive officer’s performance and our publiccommon share price. TheConsistent with prior years, the Compensation Committee determined that 50 percent50% of the annual “refresh” equity awards that were granted to our chief executive officer and executive vice president andour chief financial officer would consist of performance-based awards because their roles focus more on overall corporate performance and 25 percent of the equity awards tothan our other named executive officers. For our other named executive officers, the Compensation Committee determined that 25% of the equity awards would consist of performance-based awards. Performance-based awards granted in fiscal 20142017 to our named executive officers are earned according to the following performance criteria.criteria (determined based on performance in fiscal 2017). For fiscal 2014,2017, for purposes of our performance-based awards, operating income is calculated consistent with our Management Bonus Plan. Consistent with our Management Bonus Plan, for purposes of determining achievement levels for performance-based RSUs for fiscal 2014 grants, the impact on the Company’s results associated with the GTAT bankruptcy were excluded as an extraordinary event out of the control of our management.

The Compensation Committee determined, based our actual results for fiscal 2013,2017, that 91%100% of the performance-based awards granted to oureligible named executive officers in fiscal 20142017 were earned. The remaining 9% of such performance-based awards for each applicable executive officer were cancelled.

Grant Practices. We have implemented procedures to regularize our equity award grant process, such asby making new hire grants and annual executive grants on the same day each month. The Compensation Committee has not granted, nor does it intend in the future to grant, equity compensation awards to executives in anticipation of the release of material nonpublic information that is likely to result in changes to the price of our common stock, such as a significant positive or negative earnings announcement. Similarly, the Compensation Committee has not timed, nor does it intend in the future to time, the release of material nonpublic information based on equity award grant dates. Because our equity awards typically vest over multiple years, we believe recipients are motivated to see our stock price rise in the long-term rather than benefit from an immediate but short-term increase in the price of our stock following a grant.

Other Benefit Plans

Deferred Compensation. We maintain anon-qualified deferred compensation plan, which allows eligible employees, including executive officers and directors, to voluntarily defer receipt of the portion of his/her salary above a specified amount and all or a portion of a bonus payment until the date or dates elected by the participant, thereby allowing the participating employee to defer taxation on such amounts. This plan gives highly compensated employees the opportunity to defer more compensation than they would otherwise be permitted to defer under atax-qualified retirement plan, such as our 401(k) plan. We believe that deferred compensation is a competitive practice to enable us to attract and retain top talent. We do not make matching or other employer contributions to the deferred compensation plan because we believe the deferral opportunity is enough of a benefit on its own.

Executive Perquisites. We offer limited perquisites to our executive officers. In addition to health care coverage that is generally available to our other employees, our executive officers are eligible for annual physical examinations more extensive than under the Company’s standard plans. Our Chief Executive Officer and employees in sales and marketingIn connection with Mr. Lev’s assignment to our Asian facilities at our request, we also received a car allowance. Because Mr. Lev relocated to Singapore to serve as our senior vice president of Asia, we agreed to provide

Mr. Lev with a housing and car allowance. In addition, we agreed to make Mr. Lev whole for any income taxes for which he is responsible above that which he would be responsible for if he received a comparable salary as a resident the United States. No such tax equalization payments were made to Mr. Lev for fiscal 2014.2017. See “—Summary Compensation Table” below for more information.

Other Benefits. We also offer a number of other benefits to the executive officers pursuant to benefit programs that provide for broad-based employee participation. For example, our retirement plan is atax-qualified 401(k) plan, which is a broad-based employee plan. Under the 401(k) plan, all participating employees (including executive officers) are eligible to receive limited matching contributions that are subject to vesting over time.

The main objectives of our benefits programs are to give our employees access to quality healthcare, financial protection from unforeseen events, assistance in achieving retirement financial goals, enhanced health and productivity and to provide support for global workforce mobility, in full compliance with applicable legal requirements. These generally available benefits typically do not specifically factor into decisions regarding an individual executive’s total compensation or equity award package.

Post-Termination Arrangements

Our post-termination arrangements with our named executive officers are described in this proxy statement below. We believe the severance benefits under these agreements or policies are reasonable in amount, and provide a protection to key executive officers who would be likely to receive similar benefits from our competitors. The Compensation Committee reviews the potential costs and triggering events of employment and severance agreements and policies before approving them and will continue to consider appropriate and reasonable measures to encourage retention.

Accounting and Tax Considerations

In designing itsour executive compensation programs, the Compensation Committee generally considers the accounting and tax effects as well as direct costs. For example, we intend to limit the accounting expense for our equity compensation programs in an amount determined by the Compensation Committee from time to time. When determining how to apportion between differing elements of compensation, the goal is to meet our compensation objectives while maintaining cost neutrality. For example, if we increase benefits under one program resulting in higher compensation expense, we may seek to decrease costs under another program based on our determination of the affordability level. We recognize a charge to earnings for accounting purposes when equity awards are granted. The Compensation Committee considers the impact to dilution and overhang when making decisions pertaining to equity instruments.

We do not require executive compensation to be tax deductible for the Company, but instead balance the cost and benefits of tax deductibility to comply with our executive compensation goals.

Compensation Committee Report

The Compensation Committee of the Board of Directors of Ultra Clean Holdings, Inc. has reviewed and discussed the Compensation Discussion and Analysis, which appears in this proxy statement, with the

management of Ultra Clean Holdings, Inc. Based on this review and discussion, the Compensation Committee recommended to the Board of Directors that the Compensation Discussion and Analysis be included in Ultra Clean Holding,Holdings, Inc.’s proxy statement.

Members of the Compensation Committee

Susan H. Billat, Chair

John Chenault

David T. ibnAle,

Thomas T. Edman

Emily M. Liggett

Summary Compensation Table

The following table shows compensation information for the three most recently completed fiscal years for our principal executive officer, our principal financial officer and our other three most highly compensated executive officers as of December 26, 201429, 2017 (collectively, our “named executive officers”):

Grants of Plan-Based Awards

The following table shows all plan-based awards granted to the named executive officers during fiscal 2014:2017: