<PAGE>
                                                                    EXHIBIT 4.12

THIS SECURITY IS A GLOBAL NOTE WITHIN THE MEANING OF THE INDENTURE HEREINAFTER
REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE THEREOF,
WHICH MAY BE TREATED BY THE COMPANY, THE TRUSTEE OR ANY AGENT THEREOF AS OWNER
AND HOLDER OF THIS SECURITY FOR ALL PURPOSES. THIS GLOBAL NOTE MAY NOT BE
EXCHANGED, IN WHOLE OR IN PART, FOR A SECURITY REGISTERED, AND NO TRANSFER OF
THIS GLOBAL NOTE IN WHOLE OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY
PERSON OTHER THAN THE DEPOSITARY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED
CIRCUMSTANCES SET FORTH IN THE INDENTURE.

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY ("DTC") TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IN EXCHANGE FOR THIS
CERTIFICATE OR ANY PORTION HEREOF 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 IS MADE TO CEDE & CO. OR TO SUCH OTHER
ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER,
PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON OTHER THAN
DTC OR A NOMINEE THEREOF IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF,
CEDE & CO., HAS AN INTEREST HEREIN.

NONE OF THE CONVERTIBLE NOTES IN RESPECT OF WHICH THIS CERTIFICATE IS ISSUED NOR
THE ORDINARY SHARES OF THE COMPANY ISSUABLE UPON CONVERSION THEREOF HAVE BEEN OR
WILL BE REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED
(THE "SECURITIES ACT") OR WITH ANY REGULATORY AUTHORITY OF ANY STATE OR OTHER
JURISDICTION OF THE UNITED STATES AND MAY NOT BE OFFERED, SOLD OR PLEDGED OR
OTHERWISE TRANSFERRED IN THE UNITED STATES OR TO, OR FOR, THE ACCOUNT OR BENEFIT
OF, ANY U.S. PERSON EXCEPT PURSUANT TO AN AVAILABLE EXEMPTION FROM THE
REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND ALL APPLICABLE STATE LAWS.
TERMS USED ABOVE HAVE THE MEANING GIVEN TO THEM IN REGULATION S UNDER THE
SECURITIES ACT.

THE CONVERTIBLE NOTES HAVE BEEN ISSUED WITH ORIGINAL ISSUE DISCOUNT ("OID") FOR
UNITED STATES FEDERAL INCOME TAX PURPOSES. UPON WRITTEN REQUEST, A
REPRESENTATIVE OF THE COMPANY WILL, BEGINNING NO LATER THAN 10 DAYS AFTER THE
CLOSING DATE, PROMPTLY INFORM A HOLDER OF THE AMOUNT OF OID AS WELL AS THE ISSUE
PRICE, THE ISSUE DATE AND THE YIELD TO MATURITY OF THE CONVERTIBLE NOTES.
HOLDERS MAY CONTACT A REPRESENTATIVE OF THE COMPANY (INITIALLY THE CHIEF
FINANCIAL OFFICER) AT 5 YISHUN STREET 23, SINGAPORE 768442.

                                REG S GLOBAL NOTE

                          ST ASSEMBLY TEST SERVICES LTD

                         1.75% CONVERTIBLE NOTE DUE 2007

<TABLE>
<S>                                                         <C>

No. S-2                                                     US$25,000,000
CUSIP No. Y8161GAA3
ISIN No. US8161GAA3
Common Code 014428593

</TABLE>

     ST Assembly Test Services Ltd, a corporation duly organized and existing
under the laws of the Republic of Singapore (herein called the "Company", which
term includes any successor Person under the Indenture referred to on the
reverse hereof), for value received, hereby promises to pay to CEDE & CO., or
registered assigns, 117.665% of the principal sum of TWENTY FIVE MILLION UNITED
STATES DOLLARS (US$25,000,000) on March 18, 2007, and to pay interest thereon in
arrears from March 18, 2002, or from the most recent Interest Payment Date to
which interest has been paid or duly provided for on the basis of a 360-day year
of twelve 30-day months, semi-annually on September 18 and March 18 in each
year, commencing September 18, 2002 at the rate of 1.75% per annum, until the
principal hereof is paid or made available for payment. The interest so payable,
and punctually paid or duly provided for, on any Interest Payment Date will, as
provided in such Indenture, be paid to the Person in whose name this Convertible
Note (or one or more Predecessor Securities) is registered at the close of
business on the Regular Record Date for such interest, which shall be March 3 or
September 3 of each year (whether or not a Business Day), as the case may be,
immediately preceding such Interest

                                       1
<PAGE>
Payment Date. Any such interest not so punctually paid or duly provided for
will forthwith cease to be payable to the Holder on such Regular Record Date and
may either be paid to the Person in whose name this Convertible Note (or one or
more Predecessor Securities) is registered at the close of business on a Special
Record Date for the payment of such Defaulted Interest to be fixed by the
Trustee, notice whereof shall be given to Holders of Convertible Notes not less
than 10 days prior to such Special Record Date, or be paid at any time in any
other lawful manner not inconsistent with the requirements of any securities
exchange on which the Convertible Notes may be listed, and upon such notice as
may be required by such exchange, all as more fully provided in such Indenture.
Payment of the principal of (and premium, if any) and interest on this
Convertible Note will be made at the office or agency of the Company maintained
for that purpose in the Borough of Manhattan, The City of New York or at such
other office or agency of the Company as may be maintained for such purpose, in
such coin or currency of the United States of America as at the time of payment
is legal tender for payment of public and private debts; provided, however, that
                                                         --------- --------
payment of interest may be made at the option of the Company (i) by check mailed
to the address of the Person entitled thereto as such address shall appear on
the Security Register or (ii) by transfer to an account maintained by the payee
located in the United States.

     The statements set forth in the legends set forth above are an integral
part of the terms of this Global Note and by acceptance hereof each holder of
this Global Note agrees to be subject to and bound by the terms and provisions
set forth in such legends.

     Reference is hereby made to the further provisions of this Convertible Note
set forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof by manual signature, this Convertible
Note shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

             [The remainder of this page intentionally left blank.]

                                       2
<PAGE>

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


Dated: March 25, 2002


                                               ST ASSEMBLY TEST SERVICES LTD


                                               By:
                                                   -----------------------------
                                                   Name:
                                                   Title:


                          Certificate of Authentication

     This is one of the 1.75% Convertible Notes Due 2007 of ST ASSEMBLY TEST
SERVICES LTD referred to in the within-mentioned Indenture.

Dated: March 25, 2002


                                               The Bank of New York
                                               as Trustee

                                               By:
                                                   -----------------------------
                                                        Authorized Signatory


<PAGE>
                          [Reverse of Convertible Note]

     This Convertible Note is one of a duly authorized issue of Convertible
Notes of the Company designated as its 1.75% Convertible Note Due 2007 (herein
called the "Convertible Notes"), unlimited in principal amount, to be issued
under an Indenture, dated as of March 18, 2002 (herein called the "Indenture"),
between the Company and The Bank of New York, as Trustee (herein called the
"Trustee"), which term includes any successor trustee under the Indenture), to
which the Indenture and all indentures supplemental thereto reference is hereby
made for a statement of the respective rights, limitations of rights, duties and
immunities thereunder of the Company, the Trustee and the Holders of the
Convertible Notes and of the terms upon which the Convertible Notes are, and are
to be, authenticated and delivered.

     This Convertible Note is redeemable at the option of the Company, as a
whole but not in part, on any date at a Redemption Price equal to the Accreted
Value, plus any accrued and unpaid interest to the Redemption Date, if the
Company determines that, as a result of any change in or amendment to the laws
or any regulations or rulings promulgated thereunder of Singapore or any
official or judicial authority thereof or therein having power to tax, or any
change in the general application or official or judicial interpretation of such
laws, regulations or rulings, or any change in the official application or
interpretation of, or any execution or amendment to, any treaty or treaties
affecting taxation to which Singapore is a party, which change, execution or
amendment becomes effective on or after the original issue date of the
Convertible Notes, the Company has been or shall be required to pay Additional
Amounts with respect to the Convertible Notes.

     This Convertible Note is redeemable at the option of the Company, in whole
or in part, at any time on or after March 18, 2004, at a Redemption Price equal
to the Accreted Value, plus any accrued and unpaid interest to the Redemption
Date; provided, however, that no such redemption may be made unless the Closing
Price per Ordinary Share on the Singapore Exchange (translated into U.S. dollars
at the Prevailing Exchange Rate on such Trading Day) or the ADSs on the Nasdaq
National Market for any 20 Trading Days in a 30 consecutive Trading Day period
ending not more than five days prior to the date on which notice of such
redemption is given, is at least 125% of the Share Conversion Price (translated
into U.S. dollars at the Fixed Exchange Rate) or of the Share Conversion Price
per ADS (translated into U.S. dollars at the Fixed Exchange Rate and taking into
account the current 10:1 Ordinary Share-to-ADS ratio), in each case as adjusted
through, and effective on, such notice date.

     Notwithstanding the foregoing, the Company may redeem all of the
Outstanding Convertible Notes, including this Convertible Note, at a Redemption
Price equal to the Accreted Value, plus any accrued and unpaid interest to the
Redemption Date if at any time the aggregate principal amount of the Convertible
Notes Outstanding is less than 5% of the aggregate principal amount of the
Convertible Notes issued pursuant to the Indenture.

     This Convertible Note, or a portion thereof equal to US$1,000 or any
integral multiple thereof, may be redeemed at the option of the Holder hereof,
unless notice of redemption of all or any portion this Convertible Note shall
have been given by the Company on or prior to the date of deposit of a demand of
redemption by the Holder hereof under this paragraph, on March 18, 2005 at a
Redemption Price equal to 110.081% of the principal amount

                                       4
<PAGE>

being redeemed, plus accrued and unpaid interest to the Redemption Date by
completing, signing and depositing at the specified office of the Paying Agent a
demand of redemption not less than 60 or more than 75 days prior to March 18,
2005.

     This Convertible Note, or a portion thereof equal to US$1,000 or any
integral multiple thereof, is subject to repayment by the Company at the option
of the Holder hereof upon the occurrence of certain Repayment Events described
in the Indenture (including events relating to a Change of Control of the
Company or a Delisting of the Ordinary Shares), at a Repayment Price equal to
the Accreted Value, plus any accrued and unpaid interest to the Repayment Date.
In order to be repaid at the option of the Holder, this Convertible Note, with
the "Repayment Acceptance Notice" form duly completed by the Holder hereof (or
the Holder's attorney duly authorized in writing), must be received by the
Company during normal business hours at its office or agency maintained for that
purpose in the Borough of Manhattan, The City of New York or Singapore, not
later than the date specified by the Company in its notice of the Repayment
Event in accordance with Section 1202 of the Indenture. Exercise of such option
by the Holder of this Convertible Note shall be irrevocable unless waived by the
Company.

     In the case of any redemption or repayment of Convertible Notes, interest
installments whose Stated Maturity is on or prior to the Redemption Date or
Repayment Date will be payable to the Holders of such Convertible Notes, or one
or more Predecessor Securities, of record at the close of business on the
relevant Regular Record Date referred to on the face hereof, as provided in
Section 1107 and Section 1205 of the Indenture. Convertible Notes (or portions
thereof) for whose redemption or repayment provision is made in accordance with
the Indenture shall cease to bear interest from and after the Redemption Date or
Repayment Date (as applicable).

     This Convertible Note is convertible into Ordinary Shares of the Company
or, subject to the limitations set forth below, ADSs at any time on or after
April 17, 2002 and before the close of business on the seventh day preceding the
earlier of March 18, 2007 and the Redemption Date fixed for any early
redemption, at the Share Conversion Price then in effect; provided, however,
that, if this Convertible Note is called for redemption pursuant to Section 1101
of the Indenture, such conversion right shall terminate at the close of business
on the seventh day preceding the Redemption Date for this Convertible Note
(unless the Company shall default in making the redemption payment when due, in
which case the conversion right shall terminate at the close of business on the
date such default is cured and such Convertible Note is redeemed). A Holder may
convert a portion of this Convertible Note equal to US$1,000 or any integral
multiple thereof.

     The number of Ordinary Shares issuable upon conversion of this Convertible
Note (or a portion hereof equal to US$1,000 or any integral multiple thereof)
shall be determined by dividing the principal amount (translated into Singapore
dollars at the Fixed Exchange Rate specified in the Indenture) of this
Convertible Note or portion hereof surrendered for conversion by the Share
Conversion Price per Ordinary Share in effect on the Conversion Date. The
initial Share Conversion Price is S$3.408 per Ordinary Share, subject to
adjustment for certain anti-dilution events as provided in Section 1405 of the
Indenture. The Ordinary Shares issuable upon conversion will be duly authorized,
validly issued, fully paid and nonassessable and will rank equally with all
other Ordinary Shares.

                                       5
<PAGE>

     No Holder will be entitled to receive physical share certificates in
respect of the Ordinary Shares arising from the conversion of the Convertible
Notes. Delivery of the Ordinary Shares shall be made by crediting such Ordinary
Shares to a Holder's securities account or the securities account of a Holder's
depository agent with CDP. The Company shall allot and issue the Ordinary Shares
arising from the conversion of the Convertible Notes in accordance with
instructions as set out in the conversion notice and shall deliver to CDP the
share certificate(s) relating to such Ordinary Shares in the name of CDP for the
credit of the Holder's securities account or the securities account of Holder's
depository agent as specified in the Conversion Notice as soon as practicable,
and in any event not later than 14 days, after the Conversion Date, subject to
all applicable laws and in accordance with the Indenture. The Company will
register the Person or Persons designated for the purpose in the Conversion
Notice as Holder(s) of the relevant number of Ordinary Shares in its share
register. The Person or Persons specified for that purpose will become the
Holder of record of the number of Ordinary Shares issuable upon conversion with
effect from the date he is or they are registered as such in the Company's share
register (the "Registration Date").

     Subject to the limitations set out in the Indenture and the ability to
provide the representations and agreements set out in the Conversion Notice, the
form of which set forth in Section 206 of the Indenture, a Holder may elect to
receive Ordinary Shares upon conversion in the form of ADSs. In such event, the
Company agrees to, on behalf of such Holder, as soon as practicable, deliver to
and deposit with the ADS Depositary or its custodian, in accordance with the
terms of the ADS Deposit Agreement, such number of Ordinary Shares as the Holder
would have received upon conversion had he not elected to receive such Ordinary
Shares in the form of ADSs. Such Ordinary Shares will be registered in the name
of the ADS Depositary or its nominee. Subject to compliance with the terms of
the ADS Deposit Agreement, including payment of the fees and expenses of the ADS
Depositary by such Holder, the ADS Depositary will issue such number of ADSs
representing the deposited Ordinary Shares to such Holder based on the
applicable Ordinary Share-to-ADS ratio then in effect.

     All calculations relating to redemption and conversion, including
adjustment of the Share Conversion Price, will be made to the nearest 0.01 of an
Ordinary Share or other property or the nearest cent. However, fractions of
Ordinary Shares will not be issued on conversion or deposited with the ADS
Depositary, and no cash adjustments will be made in respect of any such
fraction. Under the ADS Deposit Agreement, the ADS Depositary will not issue
fractions of ADSs.

     To convert this Convertible Note, a Holder must, during the normal business
hours at the office of the Conversion Agent, in the Borough of Manhattan, The
City of New York, (a) complete and manually sign a "Conversion Notice"
substantially in the form included herein, including an election on whether to
receive Ordinary Shares or ADSs upon conversion, and deliver such notice to the
Conversion Agent, and (b) surrender this Convertible Note to the Conversion
Agent duly endorsed or assigned to the Company or in blank (such date of receipt
by the Conversion Agent, the "Conversion Notice Date); provided, that
appropriate endorsements and transfer documents, if any, required by the
Registrar or the Conversion Agent must be furnished and any required transfer or
similar tax and other required payments must be paid.

                                       6
<PAGE>
     The Indenture contains various provisions concerning circumstances where
the record date set for a dividend on the Ordinary Shares or an Adjustment
Effective Date for the adjustment of the Share Conversion Price falls between
the Conversion Date and the Registration Date.

     Notwithstanding the conversion rights referred to above, at any time when a
Conversion Notice has been properly deposited with the Conversion Agent, the
Company shall have the option to pay to the relevant Holder an amount of cash in
US dollars equal to the Cash Settlement Amount in order to satisfy such
conversion right in full. The Company is required to provide notice of its
exercise of the cash settlement option in the form provided in the Indenture
(the "Cash Settlement Notice") to the relevant Holder as soon as practicable but
no later than the fifth Business Day following the Conversion Notice Date (the
"Cash Settlement Notice Date"). The Cash Settlement Notice must specify the
number of Ordinary Shares or ADSs in respect of which the Company will make such
a cash payment. The Company will pay the Cash Settlement Amount not less than
five Trading Days but no later than the tenth Trading Day following the Cash
Settlement Notice Date.

     No payment or adjustment will be made for accrued and unpaid interest on
this Convertible Note when delivered for conversion. The delivery of the fixed
number of Ordinary Shares or ADSs upon conversion will be deemed to satisfy the
Company's obligation to apply the principal amount and any accrued and unpaid
premium and interest on this Convertible Note from the Interest Payment Date
immediately preceding the Conversion Date to the Conversion Date.

     If the Holder hereof surrenders this Convertible Note for conversion after
the close of business on the Regular Record Date for the payment of an
installment of interest and before the opening of business on the related
Interest Payment Date, then, notwithstanding such conversion, the interest
payable on such Interest Payment Date shall be paid to the Holder of this
Convertible Note on such Regular Record Date. In such event, unless this
Convertible Note has been called for redemption on a Redemption Date prior to
that Interest Payment Date, this Convertible Note, when surrendered for
conversion, must be accompanied by delivery of a check or draft payable to the
Company in an amount equal to the interest payable on such Interest Payment Date
on the portion so converted. If such payment does not accompany this Convertible
Note, this Convertible Note shall not be converted.

     A Conversion Notice once given will be irrevocable and may not be withdrawn
without the prior written consent of the Company. The Company or the Conversion
Agent on its behalf may reject any incomplete or incorrect Conversion Notice.
All costs and expenses incurred by an incomplete or incorrect conversion notice
will be for the account of the relevant Holder.

     As conditions precedent to conversion, the Holder must pay to the
Conversion Agent any taxes and capital, stamp, issue and registration duties
arising on conversion, other than any taxes or capital or stamp duties payable
in Singapore in respect of the allotment and issuance of the Ordinary Shares and
listing of the Ordinary Shares upon conversion. In addition, the Holder will be
required to pay any tax or duty relating to any disposal or any deemed disposal
relating to conversion and transfer involved in the issue or delivery of the
Ordinary Shares upon

                                       7
<PAGE>
conversion in a name other than such Holder's. The Company will pay all other
expenses arising on the issue, allotment and delivery of the Ordinary Shares
issuable upon conversion. The Holder will be required to pay applicable fees and
expenses of the Depositary upon conversion to ADSs.

     In the event of conversion or repayment of this Convertible Note in part
only, a new Convertible Note or Convertible Notes for the unpaid portion hereof
shall be issued in the name of the Holder hereof upon the cancellation hereof.

     If an Event of Default shall occur and be continuing, the principal of all
the Convertible Notes may be declared due and payable in the manner and with the
effect provided in the Indenture.

     The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders under the Indenture at any time by the
Company and the Trustee with the consent of the Holders of a majority in
aggregate principal amount of the Convertible Notes at the time Outstanding. The
Indenture also contains provisions permitting the Holders of specified
percentages in aggregate principal amount of the Convertible Notes at the time
Outstanding, on behalf of the Holders of all the Convertible Notes, to waive
compliance by the Company with certain provisions of the Indenture and certain
past defaults under the Indenture and their consequences. Any such consent or
waiver by or on behalf of the Holder of this Convertible Note shall be
conclusive and binding upon such Holder and upon all future Holders of this
Convertible Note and of any Convertible Note issued upon the registration of
transfer hereof or in exchange herefor or in lieu hereof, whether or not
notation of such consent or waiver is made upon this Convertible Note.

     As provided in and subject to the provisions of the Indenture, the Holder
of this Convertible Note shall not have the right to institute any proceeding
with respect to the Indenture or for the appointment of a receiver or trustee or
for any other remedy thereunder, unless such Holder shall have previously given
the Trustee written notice of a continuing Event of Default with respect to the
Convertible Notes, the Holders of not less than 25% in principal amount of the
Convertible Notes at the time Outstanding shall have made written request to the
Trustee to institute proceedings in respect of such Event of Default as Trustee
and offered the Trustee indemnity, and the Trustee shall not have received from
the Holders of a majority in principal amount of Convertible Notes at the time
Outstanding a direction inconsistent with such request, and shall have failed to
institute any such proceeding, for 60 days after receipt of such notice, request
and offer of indemnity. The foregoing shall not apply to any suit instituted by
the Holder of this Convertible Note for the enforcement of any payment of
principal hereof or interest hereon on or after the respective due dates
expressed herein.

     No reference herein to the Indenture and no provision of this Convertible
Note or of the Indenture shall alter or impair the obligation of the Company,
which is absolute and unconditional, to pay the principal of and interest on
this Convertible Note at the times, place, and rate, and in the coin or
currency, herein prescribed.

                                       8
<PAGE>

     As provided in the Indenture and subject to certain limitations therein set
forth, the transfer of this Convertible Note is registrable in the Security
Register, upon surrender of this Convertible Note for registration of transfer
at the office or agency of the Company in New York and Singapore, duly endorsed
by, or accompanied by a written instrument of transfer in form satisfactory to
the Company and the Security Registrar duly executed by the Holder hereof or his
attorney duly authorized in writing, and thereupon one or more new Convertible
Notes, of authorized denominations and for the same aggregate principal amount,
will be issued to the designated transferee or transferees.

     The Convertible Notes are issuable only in registered form without coupons
in denominations of US$1,000 and any integral multiple thereof. As provided in
the Indenture and subject to certain limitations therein set forth, Convertible
Notes are exchangeable for a like aggregate principal amount of Convertible
Notes of a different authorized denomination, as requested by the Holder
surrendering the same.

     No service charge shall be made for any such registration of transfer or
exchange, but the Company may require payment from the Holder of a sum
sufficient to cover any tax or other governmental charge payable in connection
therewith.

     Prior to due presentment of this Convertible Note for registration of
transfer the Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name this Convertible Note is registered as the
owner hereof for all purposes, whether or not this Convertible Note be overdue,
and neither the Company, the Trustee nor any such agent shall be affected by
notice to the contrary.

     All capitalized terms used but not defined in this Convertible Note shall
have the meanings assigned to them in the Indenture.

                                       9
<PAGE>
                    SCHEDULE OF EXCHANGES OF DEFINITIVE NOTES

     The following exchanges of a part of this Global Note for Definitive Notes
have been made:

<TABLE>
<CAPTION>

                                                                   Principal Amount of
                    Amount of decrease    Amount of increase in      this Global Note         Signature of
                    in Principal Amount    Principal Amount of        following such       authorized officer
Date of Exchange    of this Global Note      this Global Note     decrease (or increase)       of Trustee
----------------    -------------------   ---------------------   ----------------------   ------------------
<S>                 <C>                   <C>                     <C>                      <C>

</TABLE>


<PAGE>
                 Form of Trustee's Certificate of Authentication

     This is one of the 1.75% Convertible Notes Due 2007 of ST Assembly Test
Services Ltd referred to in the within-mentioned Indenture.


Dated:
       -------------------------



                                                The Bank of New York, as Trustee


                                                By
                                                   -----------------------------
                                                        Authorized Signatory


<PAGE>
                       Form of Holder's Redemption Notice

                           HOLDER'S REDEMPTION NOTICE

Pursuant to Section 1101(c) of the Indenture, the undersigned hereby elects to
have this Convertible Note, or any portion of the principal amount hereof (which
is US$1,000 or any integral multiple thereof, provided that the unredeemed
portion of such principal amount is US$1,000 or any integral multiple thereof)
redeemed by the Company.

The undersigned hereby directs the Paying Agent or the Company to pay it or
____________ an amount in cash equal to the Redemption Price as provided in the
Indenture.

                        [set forth payment instructions]

                                               Dated:
                                                      --------------------------


                                                      --------------------------
                                                               Signature

Principal amount to be redeemed
(US$1,000 or any integral multiple thereof):
                                                      --------------------------

Remaining principal amount following
such redemption (US$1,000 or any integral multiple
thereof):
                                                      --------------------------

NOTICE: The signature to the foregoing Holder's Redemption Notice must
correspond to the Name as written upon the face of this Convertible Note in
every particular, without alteration or any change whatsoever.


<PAGE>
                            Form of Conversion Notice

                                CONVERSION NOTICE

     The undersigned registered Holder of the within Convertible Note hereby
irrevocably exercises the option to convert this Convertible Note (or the
portion thereof specified below) into Ordinary Shares of the Company and elects
to receive such Ordinary Shares in the form of:

     [ ]  Ordinary Shares, for the principal amount of the Convertible Note of
          US$__________, or

     [ ]  ADSs, for the principal amount of the Convertible Note of
          US$__________,

pursuant to the terms of the Indenture referred to in this Convertible Note, and
directs that Ordinary Shares or ADSs, as the case may be, issuable upon
conversion and any Convertible Note representing any unconverted principal
amount hereof, be issued and delivered to the registered Holder hereof unless a
different name has been provided below:


              -----------------------------------------------------
               (Name, Address and Taxpayer Identification Number.)

     If Ordinary Shares are to be issued upon conversion of this Convertible
Note, the details of the Holder's securities account, or the securities account
of the Holder's depository agent, with The Central Depository (Pte) Limited is
as follows:

              -----------------------------------------------------

              -----------------------------------------------------

              -----------------------------------------------------

              -----------------------------------------------------

     If ADSs are to be issued upon conversion of this Convertible Note, the
details of the Holder's participant account, or the participant account of the
Holder's agent, with The Depository Trust Company is as follows:

              -----------------------------------------------------

              -----------------------------------------------------

              -----------------------------------------------------

              -----------------------------------------------------


<PAGE>

     If less than the entire principal amount of this Convertible Note is to be
converted, specify the denomination(s) of the Convertible Note(s) to be issued
for the unconverted amount (US$1,000 or any integral multiple of US$1,000):
US$__________.

     If Ordinary Shares or any portion of this Convertible Note not converted
are to be issued in the name of a person other than the undersigned, the
undersigned will pay all transfer taxes payable with respect thereto and is
delivering herewith a certificate in proper form certifying that the applicable
restrictions on transfer have been complied with.

     The undersigned hereby acknowledges that fractions of Ordinary Shares will
not be issued on conversion and no cash adjustments will be made in respect of
any such fraction. The undersigned hereby agrees that, promptly after request of
the Company or the Conversion Agent, it will furnish such proof in support of
this certificate as the Company or the Conversion Agent may request.

     As of the time of signing and delivery of this Conversion Notice, the
Holder hereby certifies for the benefit of the Company, the Trustee, the
Conversion Agent and the ADS Depositary that:

                [check one of (a), (b) or (c) only if applicable]

     [ ]  (a)  In the case of conversion to Ordinary Shares or ADSs by the
               Holder of a beneficial interest in the Reg S Global Notes, the
               undersigned represents and agrees for the benefit of the Company,
               the Trustee, the Conversion Agent and the ADS Depositary (i) that
               it or the Person who has a beneficial interest in the Convertible
               Notes is not a U.S. Person and is located outside the United
               States (within the meaning of Regulation S under the Securities
               Act) and that it or the Person who has a beneficial interest in
               the Convertible Note purchased such Convertible Note in an
               offshore transaction made in accordance with Rule 903 or Rule 904
               of Regulation S, or (ii) if it or the Person who has a beneficial
               interest in the Convertible Notes is a U.S. Person, that the
               relevant Convertible Notes and the Ordinary Shares or ADSs issued
               upon conversion are not subject to the registration requirements
               of the Securities Act.

     [ ]  (b)  In the case of conversion to Ordinary Shares by the Holder of the
               beneficial interest in the Restricted Global Notes, the
               undersigned represents and agrees for the benefit of the Company,
               the Trustee, the Conversion Agent and the ADS Depositary that it
               or the Person who has a beneficial interest in the Convertible
               Notes (I) will not offer or sell, pledge or otherwise transfer
               any of the Ordinary Shares to be delivered upon conversion except
               (i) pursuant to Rule 144A under the Securities Act to a Person it
               or the beneficial owner reasonably believes is a qualified
               institutional buyer within

                                       14
<PAGE>

               the meaning of Rule 144A under the Securities Act, purchasing of
               its own account or for the account of a qualified institutional
               buyer in a transaction meeting the requirements of Rule 144A,
               (ii) in an offshore transaction in accordance with Regulation S
               under the Securities Act, (iii) pursuant to an effective
               registration statement under the Securities Act or (iv) pursuant
               to an exemption from registration under the Securities Act
               provided by Rule 144 thereunder (if available) and (II) will not
               deposit the Ordinary Shares received upon conversion with the ADS
               Depositary in exchange for ADSs for so long as the Ordinary
               Shares are "restricted securities" within the meaning of Rule 144
               under the Securities Act.

     [ ]  (c)  In the case of conversion to ADSs by the Holder of a beneficial
               interest in the Restricted Global Notes, the undersigned
               represents and agrees for the benefit of the Company, the
               Trustee, the Conversion Agent and the ADS Depositary that it or
               the person who has a beneficial interest in the Convertible Notes
               has satisfied the holding period for restricted securities and
               other criteria provided by Rule 144 under the Securities Act such
               that none of the Ordinary Shares deposited with the ADS
               Depositary in exchange for ADSs upon conversion of the Restricted
               Global Notes will be "restricted securities" under the Securities
               Act.

     Terms used and not defined in this Conversion Notice are used with the same
meanings ascribed thereto in the Indenture pursuant to which the attached
Convertible Note is issued.


Dated:


                                              By:
                                                  ------------------------------
                                              Signature of Registered Holder

For Conversion Agent's Use only:

(A)      Conversion Date: _______________
(B)      Conversion Price on Conversion Date: ________________
(C)      Number of Ordinary Shares or ADSs (as applicable) issuable:________

                                       15
<PAGE>
                  Form of Holder's Repayment Acceptance Notice

                      HOLDER'S REPAYMENT ACCEPTANCE NOTICE

Pursuant to Section 1201 of the Indenture, the undersigned hereby elects to have
this Convertible Note, or any portion of the principal amount hereof (which is
US$1,000 or any integral multiple thereof, provided that the portion not so
repurchased of such principal amount is US$1,000 or any integral multiple
thereof) repurchased by the Company.

The undersigned hereby directs the Trustee or the Company to pay it or
____________ an amount in cash equal to the Redemption Price as provided in the
Indenture.

                        [set forth payment instructions]

                                               Dated;
                                                      --------------------------



                                                      --------------------------
                                                               Signature

Principal amount to be repurchased
(US$1,000 or any integral multiple thereof):
                                                      --------------------------

Remaining principal amount following
such repayment (US$1,000 or any integral multiple
thereof):
                                                      --------------------------


<PAGE>
                         Form of Cash Settlement Notice

                             CASH SETTLEMENT NOTICE

     Pursuant to Section 1404 of the Indenture, we hereby acknowledge receipt of
your Conversion Notice and notify you of our exercise of our cash settlement
option with respect to your conversion. The number of Ordinary Shares or ADSs
which you are entitled to receive and in respect of which we shall provide you
with the Cash Settlement Amount in order to satisfy such conversion right is set
forth below. Please use the form below to provide us with your payment
instructions if you have not done so already.

                                               Dated:
                                                      --------------------------


                                                      --------------------------
                                                               Signature

Number of Ordinary Shares: __________________________

Number of ADSs:            __________________________

The undersigned hereby directs the Trustee or the Company to pay it or
____________ the Cash Settlement Amount as provided in the Indenture.

                        [set forth payment instructions]

                                               Dated:
                                                      --------------------------


                                                      -------------------------
                                                               Signature

                                       17
<PAGE>
     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.


                                             ST ASSEMBLY TEST SERVICES LTD


                                             By: /s/ Tan Lay Koon
                                                 ------------------------------
                                                 Name: Tan Lay Koon
                                                 Title: Chief Financial Officer




                         Certificate of Authentication

     This is one of the 1.75% Convertible Notes Due 2007 of ST Assembly Test
Services Ltd referred to in the within-mentioned Indenture.

Dated March 25, 2002


                                             The Bank of New York
                                             as Trustee

                                             By:  /s/ Kelvyn Ee
                                                 --------------------------
                                                    Authorized Signatory