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                                                                    EXHIBIT 3.15


                          CERTIFICATE OF INCORPORATION
                                       OF
                            PLEXUS ENTERPRISES, INC.


      FIRST:  The name of the corporation is Plexus Enterprises, Inc.

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

      THIRD:  The purpose of 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 one thousand (1,000) shares of Common Stock, par
value $.01 per share.

      FIFTH:  The period of duration of the corporation is perpetual.

      SIXTH:  The business and affairs of the corporation shall be managed by
or under the direction of the Board of Directors.  The directors may be
removed, for cause or without cause, in accordance with the by-laws of the
corporation.

      SEVENTH: In furtherance and not in limitation of the powers conferred by
the laws of the State of Delaware, the Board of Directors is expressly
authorized to make, alter, adopt, amend, change or repeal the by-laws of the
corporation.

      EIGHTH: The corporation reserves the right to amend, alter, change or
repeal any provision contained in this Certificate of Incorporation in the
manner now or hereafter prescribed by the laws of the State of Delaware. All
rights herein conferred are granted subject to this reservation.
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      NINTH: Each owner or holder of any shares of stock or other securities of
the corporation shall be entitled as such to the number of votes per share
allocated in this Certificate of Incorporation and shall not have the right to
cumulate such votes in any election for directors.

      TENTH: The corporation shall indemnify to the fullest extent permitted by,
and in the manner permissible under, the laws of the State of Delaware any
person (and heirs, executors, administrators and estate of such person) made, or
threatened to be made, a party to any threatened, pending or completed action,
suit or proceeding, whether criminal, civil, administrative or investigative, by
reason of the fact that he is or was a director or officer of the corporation,
or served another corporation, partnership, joint venture, trust or other
enterprise as a director, advisory director, officer, employee or agent at the
request of the corporation, against expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement actually and reasonably incurred
by such person in connection with such action, suit or proceeding. The Board of
Directors in its discretion shall have the power on behalf of the corporation to
indemnify similarly any person, other than a director or officer, made a party
to any threatened, pending or completed action, suit or proceeding by reason of
the fact that he is or was an advisory director, employee or agent of the
corporation. The provisions of this Article Tenth shall be applicable to persons
who have ceased to be directors, advisory directors, officers, employees or
agents of the corporation and shall inure to the benefit of their heirs,
executors and administrators.

      Pursuant to section 102(b)(7) (or any successor statute) of the General
Corporation Law of the State of Delaware, the personal liability of a director
to the corporation or the stockholders of the corporation for monetary damages
for breach of fiduciary duty is hereby eliminated. The terms of the preceding
sentence, however, shall not eliminate or limit the liability of a director (i)
for any breach of the director's duty of loyalty to the corporation or the
stockholders of the corporation, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 (or a successor statute) of the General Corporation Law of the State
of Delaware, or (iv) for any transaction from which the director derived an
improper personal benefit.

      ELEVENTH:  The incorporator is K. A. Widdoes, whose mailing address is
c/o The Corporation Trust Company, 1209 Orange Street, Wilmington, Delaware
19801.

      The undersigned, being the incorporator named above, for the purposes of
organizing a corporation pursuant to the General Corporation Law of the State of
Delaware, does make this certificate, hereby declaring and certifying that this
is her act and deed and the facts herein stated are true, and accordingly has
hereunto set his hand this 18th day of December, 1995.


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                                    /s/ K. A. Widdoes
                                    ---------------------------------
                                    K. A. Widdoes, Incorporator


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