<PAGE>

                                                                     Exhibit 2.2

                             CERTIFICATE OF MERGER

                                    MERGING

                             EAST ACQUISITION CORP.

                                 WITH AND INTO

                              CMC INDUSTRIES, INC.

                    _______________________________________

           Pursuant to Section 251 of the General Corporation Law of
                             the State of Delaware

                    _______________________________________


       East Acquisition Corp., a Delaware corporation ("Merger Sub"), and CMC
Industries, Inc., a Delaware corporation ("Target"), DO HEREBY CERTIFY AS
FOLLOWS:

       FIRST: That Merger Sub was incorporated on May 6, 1999, pursuant to the
Delaware General Corporation Law (the "Delaware Law"), and that Target was
incorporated on May 23, 1990, under the name "Cortelco Acquisition Corporation",
pursuant to the Delaware Law.

       SECOND: That an Agreement and Plan of Merger and Reorganization (the
"Merger Agreement"), dated as of May 10, 1999, among ACT Manufacturing, Inc., a
Massachusetts corporation, Merger Sub and Target, setting forth the terms and
conditions of the merger of Merger Sub with and into Target (the "Merger"), has
been approved, adopted, certified, executed and acknowledged by each of the
constituent corporations in accordance with Section 251(c) of the Delaware Law.

       THIRD: That the name of the surviving corporation (the "Surviving
Corporation") shall be CMC Industries, Inc., a Delaware corporation.

       FOURTH: That pursuant to the Merger Agreement, the Certificate of
Incorporation of the Surviving Corporation shall be amended and restated as
attached hereto as Exhibit A.
<PAGE>

       FIFTH: That an executed copy of the Merger Agreement is on file at the
principal place of business of the Surviving Corporation at the following
address:
               CMC Industries, Inc.
               4950 Patrick Henry Drive
               Santa Clara, California 95054

       SIXTH: That a copy of the Merger Agreement will be furnished by the
Surviving Corporation, on request and without cost, to any stockholder of any
constituent corporation.

       SEVENTH: That the Merger shall become effective upon the filing of this
Certificate of Merger with the Secretary of State of the State of Delaware.



                  [Remainder of Page Intentionally Left Blank]
<PAGE>

       IN WITNESS WHEREOF: each of Merger Sub and Target has caused this
Certificate of Merger to be executed in its corporate name this 29th day of
July, 1999.

                                                    EAST ACQUISITION CORP.



                                                    By: /s/ John A. Pino
                                                        ----------------
                                                       John A. Pino, President



                                                    CMC INDUSTRIES, INC.



                                                    By: /s/ Matthew G. Landa
                                                       --------------------
                                                       Matthew G. Landa,
                                                       President and
                                                       Chief Executive Officer


                                                                       EXHIBIT A

                             AMENDED AND RESTATED
                         CERTIFICATE OF INCORPORATION

                                      OF

                             CMC INDUSTRIES, INC.
                                    ******


     FIRST.     The name of the corporation is CMC Industries, Inc. (the
"Corporation").

     SECOND.    The address of the registered office of the Corporation in the
State of Delaware is 1209 Orange Street, in the City of Wilmington, New Castle
County, Delaware 19801. The name of its registered agent at such address is The
Corporation Trust Company.

     THIRD.     The nature of the business or purposes to be conducted or
promoted by the Corporation is to engage in any lawful act or activity for which
corporations may be organized under the General Corporation Law of the State of
Delaware.

     FOURTH.    The total number of shares of stock which the Corporation shall
have authority to issue is 1,000 shares of Common Stock, $.01 par value per
share.

     FIFTH.     The Corporation is to have perpetual existence.

     SIXTH.     In furtherance and not in limitation of the powers conferred by
the laws of the State of Delaware:

     A.    The Board of Directors of the Corporation is expressly authorized to
     adopt, amend or repeal the By-laws of the Corporation.

     B.    Elections of Directors need not be by written ballot unless the
     By-laws of the Corporation shall so provide.

     C.    The books of the Corporation may be kept at such place within or
without the State of Delaware as the By-laws of the Corporation may provide or
as may be designated from time to time by the Board of Directors of the
Corporation.

     SEVENTH.   The Corporation eliminates the personal liability of each
member of its Board of Directors to the Corporation or its stockholders for
monetary damages for breach of fiduciary duty as a director, provided, however,
that, to the extent provided by applicable law, the foregoing shall not
eliminate the liability of a director (i) for any breach of such director's duty
of loyalty to the Corporation or its stockholders, (ii) for acts or omissions
not in good faith or which involve intentional misconduct or a knowing violation
of law, (iii) under Section 174 of Title 8 of the Delaware Code or (iv) for any
transaction from which such director derived an improper personal benefit. No
amendment to or repeal of this provision shall apply to or have any effect on
the liability or alleged liability of any director for or with respect to any
acts or omissions of such director occurring prior to such amendment or repeal.

     EIGHTH.    The Corporation reserves the right to amend or repeal any
provision contained in this Certificate of Incorporation, in the manner now or
hereafter prescribed by statute, and all rights conferred upon a stockholder
herein are granted subject to this reservation.