<PAGE>

                                                                     Exhibit 3.1

             One Ashburton Place, Boston, Massachusetts  02108-1512

                             ARTICLES OF AMENDMENT
                    (General Laws, Chapter 156B, Section 72)

We,    John A. Pino                                            , *
    -------------------------------------------------------------
President


and    Jeffrey B. Lavin                                        , * Clerk
    -------------------------------------------------------------

of    ACT Manufacturing, Inc.          ,
    -------------------------------------------------------------


                          (Exact name of corporation)

 located at:     2 Cabot Road, Hudson,  MA 01749
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                (Street address of corporation in Massachusetts)

 certify that these Articles of Amendment affecting articles numbered:

                    3
--------------------------------------------------------------------------------
         (Number those articles 1, 2, 3, 4, 5, and/or 6 being amended)

 of the Articles of Organization were duly adopted at a meeting held on July 29,
 1999, by vote of:

7,821,702 shares of Common Stock, $.01 par value  of 9,091,600 shares
---------           ----------------------------    ----------
outstanding

                     (type, class & series, if any)

          shares of                               of           shares
----------          ----------------------------    ----------
outstanding

                     (type, class & series, if any)

          shares of                               of           shares
----------          ----------------------------    ----------
outstanding

                     (type, class & series, if any)




 1**being at least a majority of each type, class or series outstanding and
 entitled to vote thereon



 *Delete the inapplicable words.  ** Delete the inapplicable clause.
 1For amendments adopted pursuant to Chapter 156B, Section 70.
 2For amendments adopted pursuant to Chapter 156B, Section 71.
<PAGE>

 Note: If the space provided under any article or item on this form is
 insufficient, additions shall be set forth on one side only of separate 8 1/2 x
 11 sheets of paper with a left margin of at least 1 inch.  Additions to more
 than one article may be made on a single sheet so long as each article
 requiring each addition is clearly indicated.
<PAGE>

To change the number of shares and the par value (if any) of any type, class or
series of stock which the corporation is authorized to issue, fill in the
following:

The total presently authorized is:


<TABLE>
<CAPTION>

        WITHOUT PAR VALUE STOCKS                              WITH PAR VALUE STOCKS
--------------------------------------------------------------------------------------------------------
    TYPE           NUMBER OF SHARES           TYPE             NUMBER OF SHARES            PAR VALUE
--------------------------------------------------------------------------------------------------------
<S>           <C>                         <C>            <C>                           <C>
Common:                0                     Common:           30,000,000                    $.01
--------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------
Preferred:             0                    Preferred:         5,000,000                     $.01
--------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------
</TABLE>


Change the total authorized to:

<TABLE>
<CAPTION>
        WITHOUT PAR VALUE STOCKS                              WITH PAR VALUE STOCKS
--------------------------------------------------------------------------------------------------------
    TYPE           NUMBER OF SHARES           TYPE             NUMBER OF SHARES            PAR VALUE
--------------------------------------------------------------------------------------------------------
<S>           <C>                         <C>            <C>                           <C>
Common:                0                     Common:           50,000,000                    $.01
--------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------
Preferred:             0                    Preferred:         5,000,000                     $.01
--------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

The foregoing amendment(s) will become effective when these Articles of
Amendment are filed in accordance with General Laws, Chapter 156B, Section 6
unless these articles specify, in accordance with the vote adopting the
amendment, a later effective date not more than thirty days after such filing,
in which event the amendment will become effective on such later date.

Later effective date:


SIGNED UNDER THE PENALTIES OF PERJURY, this  29th day of July , 1999  .

/s/ John A. Pino                                                  , *President
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/s/ Jeffrey Lavin                                                 , *Clerk
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*Delete the inapplicable words.
<PAGE>

                       THE COMMONWEALTH OF MASSACHUSETTS

                             ARTICLES OF AMENDMENT

                    (General Laws, Chapter 156B, Section 72)



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

          I hereby approve the within Articles of Amendment, and the filing fee
          in the amount of $20,000 having been paid, said article is deemed
          to have been filed with me this 29th day of July 1999.


          Effective date: July 29,1999
          ______________________________________________________________________



                           /s/ William Francis Galvin

                             WILLIAM FRANCIS GALVIN

                         Secretary of the Commonwealth



                         TO BE FILLED IN BY CORPORATION

                      PHOTOCOPY OF DOCUMENT TO BE SENT TO:



                         Kelly R. Whiting, Esq.
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                         Testa, Hurwitz & Thibeault, LLP
                         -------------------------------
                         High Street Tower
                         -----------------
                         125 High Street
                         ---------------
                         Boston, MA  02110
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