[FACE OF SECURITY]

Exhibit 4.2

[FACE OF SECURITY]

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN. THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF THE DEPOSITARY OR A NOMINEE THEREOF. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE AND, UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN DEFINITIVE FORM, THIS SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY.

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HUTCHINSON TECHNOLOGY INCORPORATED

8.50% Convertible Senior Notes due 2026

Hutchinson Technology Incorporated, a Minnesota corporation, promises to pay to Cede & Co. or registered assigns the principal amount of Forty Million Dollars ($40,000,000) on January 15, 2026.

This Security shall bear interest as specified on the other side of this Security. This Security is convertible as specified on the other side of this Security.

Additional provisions of this Security are set forth on the other side of this Security.

Dated: February 11, 2011

[SIGNATURE PAGE FOLLOWS]

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IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed.

Dated: February 11, 2011

Trustee’s Certificate of Authentication: This is one of the

Securities referred to in the within-mentioned Indenture.

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[REVERSE SIDE OF SECURITY]

HUTCHINSON TECHNOLOGY INCORPORATED

CONVERTIBLE SENIOR NOTES DUE 2026

Hutchinson Technology Incorporated, a Minnesota corporation (the “Company”, which term shall include any successor corporation under the Indenture hereinafter referred to), promises to pay interest on the principal amount of this Security at the rate of 8.50% per annum. The Company shall pay interest semiannually on January 15 and July 15 of each year (each an “Interest Payment Date”), commencing July 15, 2011. Each payment of interest will include interest accrued through the day before the relevant Interest Payment Date (or purchase or redemption date, as the case may be). Cash interest will be computed on the basis of a 360-day year comprised of twelve 30-day months.

No sinking fund is provided for the Securities.

The Company shall pay interest on this Security (except defaulted interest) to the person who is the Holder of this Security at the close of business on January 1 or July 1, as the case may be (each, a “Regular Record Date”), next preceding the related Interest Payment Date. The Holder must surrender this Security to a Paying Agent to collect payment of principal. The Company will pay principal and interest in money of the United States that at the time of payment is legal tender for payment of public and private debts. The Company may pay principal and interest in respect of any Certificated Security through the Paying Agent by check or wire payable in such money; provided, however, that a Holder with an aggregate principal amount in excess of $2,000,000 will be paid by wire transfer in immediately available funds at the election of such Holder if such Holder has provided wire transfer instructions to the Trustee at least 10 Business Days prior to the Interest Payment Date. The Company may mail an interest check to the Holder’s registered address. Notwithstanding the foregoing, so long as this Security is registered in the name of a Depositary or its nominee, all payments hereon shall be made by wire transfer of immediately available funds to the account of the Depositary or its nominee.

Any wire transfer instructions received by the Trustee will remain in effect until revoked by the Holder.

Initially, Wells Fargo Bank, National Association (the “Trustee”, which term shall include any successor trustee under the Indenture hereinafter referred to) will act as Paying Agent, Registrar and Conversion Agent. The Company may change any Paying Agent, Registrar or Conversion Agent without notice to the Holder. The Company or any of its Subsidiaries may, subject to certain limitations set forth in the Indenture, act as Paying Agent or Registrar.

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This Security is one of a duly authorized issue of Securities of the Company designated as its 8.50% Convertible Senior Notes Due 2026 (the “Securities”), issued under an Indenture dated as of February 11, 2011 (together with any supplemental indentures thereto, the “Indenture”), between the Company and the Trustee. The terms of this Security include those stated in the Indenture and those required by or made part of the Indenture by reference to the Trust Indenture Act of 1939, as amended, as in effect on the date of the Indenture. This Security is subject to all such terms, and the Holder of this Security is referred to the Indenture and said Act for a statement of them.

The Securities are senior unsecured obligations of the Company. The Indenture does not limit debt of the Company, secured or unsecured.

Prior to January 15, 2013, the Securities shall not be redeemable. The Company may, at its option, redeem the Securities for cash at the Redemption Price, in whole or in part, on any Redemption Date (or in the case of multiple redemptions, Redemption Dates) fixed by the Company (i) from time to time on or after January 15, 2013 to, but excluding, January 15, 2015, if the Closing Price of the Common Stock equals or exceeds 150% of the Conversion Price in effect for at least 20 Trading Days during the 30 consecutive Trading Day period ending on the Trading Day immediately prior to the date the Company delivers the redemption notice specified in Section 3.03 of the Indenture, and (ii) on and after January 15, 2015, at any time and from time to time. The Redemption Price shall equal 100% of the principal amount of the Securities to be redeemed, plus any accrued and unpaid interest to, but excluding, the Redemption Date; provided, however, that if the Redemption Date falls after a Regular Record Date but on or prior to the corresponding Interest Payment Date, the interest on the Securities payable on such Redemption Date will be payable to the Holders in whose names the Securities are registered at the close of business on the applicable Regular Record Date. Securities or portions of Securities called for redemption shall be convertible by the Holder until the close of business on the second Business Day prior to the relevant Redemption Date.

Notice of redemption, as set forth in Section 3.03 of the Indenture, will be mailed by first-class mail at least 30 days but not more than 60 days before a Redemption Date to each Holder of Securities to be redeemed at its registered address. Securities in denominations larger than $1,000 may be redeemed in part, but only in whole multiples of $1,000. On and after the Redemption Date, subject to the deposit with the Paying Agent of funds sufficient to pay the Redemption Price, such Securities or portions of them called for redemption will cease to be outstanding, whether or not the Security is delivered to the Paying Agent, and the rights of the Holder in respect thereof shall cease (other than the right to receive the Redemption Price).

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At the option of the Holder and subject to the terms and conditions of the Indenture, the Company shall become obligated to purchase for cash, subject to certain exceptions described in the Indenture, all or any part specified by the Holder (so long as the principal amount of such part is $1,000 or an integral multiple of $1,000) of the Securities held by such Holder on a date specified by the Company that is not less than 30 nor more than 45 days after the date of the Fundamental Change Company Notice, at a purchase price equal to 100% of the principal amount thereof together with accrued and unpaid interest, if any, to, but excluding, the Fundamental Change Repurchase Date. The Holder shall have the right to withdraw any Fundamental Change Repurchase Notice (in whole or in a portion thereof that is $1,000 or an integral multiple of $1,000) at any time prior to the close of business on the Business Day next preceding the Fundamental Change Repurchase Date by delivering a written notice of withdrawal to the Paying Agent in accordance with the terms of the Indenture.

At the option of the Holder and subject to the terms and conditions of the Indenture, the Company shall become obligated to purchase for cash all or any part specified by the Holder (so long as the principal amount of such part is $1,000 or an integral multiple of $1,000) of the Securities held by such Holder on the applicable Put Right Purchase Date at the applicable Put Right Purchase Price. The Holder shall have the right to withdraw any Put Right Purchase Notice (in whole or in a portion thereof that is $1,000 or an integral multiple of $1,000) at any time prior to the close of business on the Business Day next preceding the Put Right Purchase Date by delivering a written notice of withdrawal to the Paying Agent in accordance with the terms of the Indenture.

Subject to and upon compliance with the provisions of the Indenture, a Holder may surrender for conversion any Security that is $1,000 principal amount or integral multiples thereof. Upon conversion of a Security, the Holder of such Security shall receive a number of shares of Common Stock equal to the product of (i) the number obtained by dividing the principal amount of the Security converted by $1,000 and (ii) the Conversion Rate in effect on the applicable Conversion Date; provided, however, that in lieu of any fractional share of Common Stock, the Company shall deliver an amount of cash equal to the product of (i) such fraction of a share and (ii) the Closing Price of the Common Stock on the applicable Conversion Date (or, if the applicable Conversion Date is not a Trading Day, the Trading Day immediately preceding such Conversion Date).

The Securities are in registered form, without coupons, in denominations of $1,000 principal amount and integral multiples of $1,000 principal amount. A Holder may register the transfer of or exchange Securities in accordance with the Indenture. The Registrar may require a

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Holder, among other things, to furnish appropriate endorsements and transfer documents and to pay any taxes or other governmental charges that may be imposed in relation thereto by law or permitted by the Indenture.

The Holder of a Security may be treated as the owner of it for all purposes.

If money for the payment of principal or interest remains unclaimed for two years, the Trustee and any Paying Agent will pay the money back to the Company at its written request, subject to applicable unclaimed property law and the provisions of the Indenture. After that, Holders entitled to money must look to the Company for payment as general creditors unless an applicable abandoned property law designates another person.

Subject to certain exceptions, the Indenture or the Securities may be amended or supplemented with the consent of the Holders of at least a majority in aggregate principal amount of the Securities then outstanding, and an existing Default or Event of Default and its consequence or compliance with any provision of the Indenture or the Securities may be waived in a particular instance with the consent of the Holders of a majority in aggregate principal amount of the Securities then outstanding. Without the consent of or notice to any Holder, the Company and the Trustee may amend or supplement the Indenture or the Securities to, among other things, cure any ambiguity, defect or inconsistency or make any other change that does not adversely affect the rights of the Holders in any material respect.

When a successor corporation assumes all the obligations of its predecessor under the Securities and the Indenture in accordance with the terms and conditions of the Indenture, the predecessor corporation (except in certain circumstances specified in the Indenture) shall be released from those obligations.

Under the Indenture, an Event of Default shall occur if:

(1) the Company shall fail to pay when due the Principal or any Redemption Price, Put Right Purchase Price or Fundamental Change Repurchase Price of any Security, when the same becomes due and payable whether at the Final Maturity Date, upon redemption, repurchase, acceleration or otherwise; or

(2) the Company shall fail to pay an installment of cash interest on any of the Securities, which failure continues for 30 days after the date when due; or

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(3) the Company shall fail to deliver when due any consideration payable upon conversion of the Securities, which failure continues for 15 days; or

(4) the Company shall fail to perform or observe (or obtain a waiver with respect to) any other term, covenant or agreement contained in the Securities or the Indenture for a period of 60 days after receipt by the Company of a Notice of Default specifying such failure; or

(5) default in the payment of principal by the end of any applicable grace period or resulting in acceleration of other indebtedness of the Company for borrowed money where the aggregate principal amount with respect to which the default or acceleration has occurred exceeds $25 million and such acceleration has not been rescinded or annulled or such indebtedness repaid within a period of 30 days after receipt of a Notice of Default, provided that if any such default is cured, waived, rescinded or annulled, then the Event of Default by reason thereof would be deemed not to have occurred; or

(6) the Company pursuant to or within the meaning of any Bankruptcy Law:

(A) commences as a debtor a voluntary case or proceeding; or

(B) consents to the entry of an order for relief against it in an involuntary case or proceeding or the commencement of any case against it; or

(C) consents to the appointment of a Receiver of it or for all or substantially all of its property; or

(D) makes a general assignment for the benefit of its creditors; or

(E) files a petition in bankruptcy or answer or consent seeking reorganization or relief; or

(F) consents to the filing of such a petition or the appointment of or taking possession by a Receiver; or

(7) a court of competent jurisdiction enters an order or decree under any Bankruptcy Law that:

(A) grants relief against the Company in an involuntary case or proceeding or adjudicates the Company insolvent or bankrupt;

(B) appoints a Receiver of the Company or for all or substantially all of the property of the Company; or

(C) orders the winding up or liquidation of the Company;

and in each case the order or decree remains unstayed and in effect for 60 consecutive days.

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The term “Bankruptcy Law” means Title 11 of the United States Code (or any successor thereto) or any similar federal or state law for the relief of debtors. The term “Receiver” means any receiver, trustee, assignee, liquidator, sequestrator or similar official under any Bankruptcy Law.

Notwithstanding the above, no Event of Default under clauses (4) or (5) above shall occur until the Trustee notifies the Company in writing, or the Holders of at least 25% in aggregate principal amount of the Securities then outstanding notify the Company and the Trustee in writing, of the Default (a “Notice of Default”), and the Company does not cure the Default within the time specified in clause (4) or (5), as applicable, after receipt of such notice.

If an Event of Default (other than an Event of Default specified in clauses (6) or (7) above) occurs and is continuing with respect to the Company, the Trustee may, by notice to the Company, or the Holders of at least 25% in aggregate principal amount of the Securities then outstanding may, by notice to the Company and the Trustee, declare the principal amount and accrued and unpaid interest, if any, through the date of declaration on all the Securities to be immediately due and payable. Upon such a declaration, such principal amount and such accrued and unpaid interest, if any, shall be due and payable immediately. If an Event of Default specified in clauses (6) or (7) occurs in respect of the Company and is continuing, the principal amount and accrued but unpaid interest, if any, on all the Securities shall become and be immediately due and payable without any declaration or other act on the part of the Trustee or any Holders of Securities. The Holders of a majority in aggregate principal amount of the Securities then outstanding by notice to the Trustee may rescind an acceleration and its consequences if (a) all existing Events of Default, other than the nonpayment of the principal of the Securities which have become due solely by such declaration of acceleration, have been cured or waived; (b) the rescission would not conflict with any judgment or decree of a court of competent jurisdiction; and (c) all payments due to the Trustee and any predecessor Trustee under the Indenture have been made. No such rescission shall affect any subsequent Default or impair any right consequent thereto. Holders may not enforce the Indenture or the Securities except as provided in the Indenture. The Trustee may require indemnity satisfactory to it before it enforces the Indenture or the Securities. Subject to certain limitations, Holders of a majority in aggregate principal amount of the Securities then outstanding may direct the Trustee in its exercise of any trust or power. The Trustee may withhold from Holders notice of any continuing Default (except a Default in payment of principal or interest) if and so long as it determines that withholding notice is in their interests. The Company is required to file periodic certificates with the Trustee as to the Company’s compliance with the Indenture and knowledge or status of any Default.

Wells Fargo Bank, National Association, the initial Trustee under the Indenture, in its individual or any other capacity, may make loans to, accept deposits from and perform services for the Company or an Affiliate of the Company, and may otherwise deal with the Company or an Affiliate of the Company, as if it were not the Trustee.

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A director, officer, employee or shareholder, as such, of the Company shall not have any liability for any obligations of the Company under the Securities or the Indenture nor for any claim based on, in respect of or by reason of such obligations or their creation. The Holder of this Security by accepting this Security waives and releases all such liability. The waiver and release are part of the consideration for the issuance of this Security.

This Security shall not be valid until the Trustee or an authenticating agent manually signs the certificate of authentication on the other side of this Security.

Customary abbreviations may be used in the name of the Holder or an assignee, such as: TEN COM (= tenants in common), TEN ENT (= tenants by the entireties), JT TEN (= joint tenants with right of survivorship and not as tenants in common), CUST (= Custodian) and UGMA (= Uniform Gifts to Minors Act).

All terms defined in the Indenture and used in this Security but not specifically defined herein are defined in the Indenture and are used herein as so defined.

In the case of any conflict between the provisions of this Security and the Indenture, the provisions of the Indenture shall control. This Security and the Indenture shall be governed by, and construed in accordance with, the laws of the State of New York.

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ASSIGNMENT FORM

To assign this Security, fill in the form below:

I or we assign and transfer this Security to

(Insert assignee’s social security or tax I.D. number)

(Print or type assignee’s name, address and zip code)

and irrevocably appoint

agent to transfer this Security on the books of the Company. The agent may substitute another to act for him or her.

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CONVERSION NOTICE

To convert this Security into Common Stock of the Company, check the box:  ¨

To convert only part of this Security, state the principal amount to be converted (must be $1,000 or an integral multiple of $1,000): $            .

If you want the stock certificate made out in another person’s name, fill in the form below:

(Insert assignee’s social security or tax I.D. number)

(Print or type assignee’s name, address and zip code)

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FUNDAMENTAL CHANGE REPURCHASE NOTICE

To: Hutchinson Technology Incorporated

The undersigned registered owner of this Security hereby irrevocably acknowledges receipt of a notice from Hutchinson Technology Incorporated (the “Company”) as to the occurrence of a Fundamental Change with respect to the Company and requests and instructs the Company to purchase the entire principal amount of this Security, or the portion thereof (which is $1,000 or an integral multiple thereof) below designated, in accordance with the terms of the Security and the Indenture referred to in the Security at the Fundamental Change Repurchase Price, together with accrued and unpaid interest, to, but excluding, such date, to the registered Holder hereof.

Principal amount to be purchased (in an

integral multiple of $1,000, if less than all):

NOTICE: The signature to the foregoing Election must correspond to the Name as written upon the face of this Security in every particular, without any alteration or change whatsoever.

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OPTION TO ELECT PURCHASE

ON SPECIFIED DATES

To: Hutchinson Technology Incorporated

The undersigned hereby requests and instructs Hutchinson Technology Incorporated to purchase the entire principal amount of this Security, or the portion thereof (which is $1,000 or an integral multiple thereof) below designated, on                      in accordance with the terms of the Indenture referred to in this Security at the Put Right Purchase Price for the next occurring Put Right Purchase Date to the registered Holder hereof.

Principal amount to be purchased (in an

integral multiple of $1,000, if less than all):

NOTICE: The signature to the foregoing Election must correspond to the Name as written upon the face of this Security in every particular, without any alteration or change whatsoever.

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SCHEDULE OF EXCHANGES OF SECURITIES

The following exchanges, purchase, redemptions, purchases or conversions of a part of this Global Security have been made:

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