<PAGE>

COMMON SHARES                                                      COMMON SHARES

PIII-                      [LOGO OF PECO II, INC.]

                                                               -----------------
                                                               CUSIP 705221 10 9
                                                               -----------------
INCORPORATED UNDER THE
LAWS OF THE STATE OF OHIO

THIS CERTIFIES THAT




is the owner of

   the above stated number of fully paid and non-assessable Common Shares,
                             without par value, of

                                 PECO II, Inc.

transferable on the books of the Company by the holder hereof in person or by
duly authorized attorney upon surrender of this certificate properly endorsed.
This certificate is not valid unless countersigned by the Transfer Agent and
Registrar.

     WITNESS the facsimile signature of the duly authorized officer of the
Company.

Dated:

/s/ Sandra C. Frankhouse                   /s/ Matthew P. Smith

       Secretary                    President and Chief Executive Officer

COUNTERSIGNED AND REGISTERED:
                     NATIONAL CITY BANK
                                            TRANSFER AGENT
                                             AND REGISTRAR
BY:
                                         AUTHORIZED SIGNATURE
<PAGE>

                                 PECO II, Inc.

     THE CORPORATION WILL FURNISH WITHOUT CHARGE TO EACH SHAREHOLDER WHO SO
REQUESTS WITHIN FIVE DAYS AFTER RECEIPT OF SUCH REQUEST, A STATEMENT OF THE
EXPRESS TERMS OF EACH CLASS AND EACH SERIES OF EACH CLASS OF SHARES WHICH THE
CORPORATION IS AUTHORIZED TO ISSUE. SUCH REQUEST SHOULD BE IN WRITING AND
ADDRESSED TO THE SECRETARY OF THE CORPORATION AT 1376 STATE ROUTE 598, GALION,
OHIO 44833.

     The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

     TEN COM -- as tenant in common
     TEN ENT -- as tenants by the entireties
     JT TEN  -- as joint tenants with right of survivorship and not as tenants
                in common

     UNIF GIFT MIN ACT -- __________ Custodian __________
                            (Cust)              (Minor)
                          under Uniform Gift to Minors
                          Act ___________________________
                                       (State)

     For Value Received, ______________________ HEREBY SELL, ASSIGN AND TRANSFER
UNTO

PLEASE PRINT OR INSERT SOCIAL SECURITY OR OTHER
      IDENTIFYING NUMBER OF ASSIGNEE
--------------------------------------

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                  PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS

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                                                                         SHARES
-------------------------------------------------------------------------
REPRESENTED BY THE WITHIN CERTIFICATE, AND DO HEREBY IRREVOCABLY CONSTITUTE AND
APPOINT                                                                ATTORNEY,
       ----------------------------------------------------------------
TO TRANSFER THE SAID SHARES ON THE BOOKS OF THE WITHIN-NAMED CORPORATION WITH
FULL POWER OF SUBSTITUTION IN THE PREMISES.

Dated:                         Signatures(s):
      ----------------------                 -----------------------------------



                        --------------------------------------------------------
                        NOTICE: THE SIGNATURE(S) TO THIS ASSIGNMENT MUST
                        CORRESPOND WITH THE NAME(S) AS WRITTEN UPON THE FACE OF
                        THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION
                        OR ENLARGEMENT OR ANY CHANGE WHATEVER.


Signature(s) Guaranteed:
                        --------------------------------------------------------
                        THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE
                        GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND
                        LOAN ASSOCIATIONS AND CREDIT UNIONS) WITH MEMBERSHIP BY
                        AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM
                        PURSUANT TO S.E.C. RULE 17AO-15