content: <PAGE>   1
  
      As filed with the Securities and Exchange Commission on January 14, 2000
                                                               FILE NO. 333-
  ================================================================================
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 20549
  
                                --------------------
  
                                      FORM S-8
                               REGISTRATION STATEMENT
                                        UNDER
                             THE SECURITIES ACT OF 1933
  
                                --------------------
  
                               BTU INTERNATIONAL, INC.
               (Exact name of registrant as specified in its charter)
  
                DELAWARE                                       04-2781248
      (State or other jurisdiction                          (I.R.S. Employer
    of incorporation or organization)                    Identification Number)
  
                                   23 ESQUIRE ROAD
                        NORTH BILLERICA, MASSACHUSETTS 01862
                                   (978) 667-4111
            (Address of principal executive offices, including zip code)
  
                 BTU INTERNATIONAL, INC. 1993 EQUITY INCENTIVE PLAN
      BTU INTERNATIONAL, INC. 1998 STOCK OPTION PLAN FOR NON-EMPLOYEE DIRECTORS
                              (Full title of the plans)
  
                             ---------------------------
  
                               PAUL J. VAN DER WANSEM
                        CHAIRMAN AND CHIEF EXECUTIVE OFFICER
                               BTU INTERNATIONAL, INC.
                        NORTH BILLERICA, MASSACHUSETTS 01862
                                   (978) 667-4111
                (Name and address, including zip code, and telephone
                 number, including area code, of agent for service)
  
                                --------------------
  
                           CALCULATION OF REGISTRATION FEE
  <TABLE>
  <CAPTION>
  ===================================================================================================================
                                                Amount       Proposed maximum      Proposed maximum        Amount of
              Title of each class of             to be        offering price      aggregate offering     registration
            securities to be registered       registered         per share               price                fee
  -------------------------------------------------------------------------------------------------------------------
  
  <S>                                        <C>                <C>                  <C>                    <C>
  Common Stock, $.01 par value               550,000 shs.       $5.4688(1)           $3,007,840(1)          $794.07
  
  ===================================================================================================================
  </TABLE>
  
  (1) FOR PURPOSES OF DETERMINING THE REGISTRATION FEE, THE MAXIMUM PER SHARE AND
  AGGREGATE OFFERING PRICES HAVE BEEN DETERMINED, PURSUANT TO RULE 457(h) OF THE
  SECURITIES ACT OF 1933, ON THE BASIS OF THE AVERAGE OF HIGH AND LOW PRICES OF
  THE COMMON STOCK REPORTED IN THE NASDAQ NATIONAL MARKET SYSTEM ON JANUARY 10,
  2000.
  
  ================================================================================
                              EXHIBIT INDEX ON PAGE 7;
                                 PAGE 1 OF 7 PAGES.
  
  
  
  
  <PAGE>   2
  
  
  
  PART I
  
  INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS
  
  Note: The document(s) containing the information required by Item 1 of this Form
  S-8 and the statement of availability of information of BTU International, Inc.
  (the "Registrant"), and other information required by Item 2 of this Form will
  be sent or given to employees as specified by Rule 428 under the Securities Act
  of 1933, as amended (the "Securities Act"). In accordance with Rule 428 and the
  requirements of Part I of Form S-8, such documents are not being filed with the
  Securities and Exchange Commission (the "Commission") either as part of this
  Registration Statement or as prospectuses or prospectus supplements pursuant to
  Rule 424. The Registrant shall maintain a file of such documents in accordance
  with the provisions of Rule 428. Upon request, the Registrant shall furnish to
  the Commission or its staff a copy or copies of any or all of the documents
  included in such file.
  
  
  
  
                                         -2-
  
  
  <PAGE>   3
  
  
  
  PART II
  
  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  Item 3.  INCORPORATION DOCUMENTS BY REFERENCE.
  
           The following documents previously filed by the Registrant with the
  Commission pursuant to the Securities Exchange Act of 1934, as amended (the
  "Exchange Act") are hereby incorporated by reference:
  
           (a)      The Registrant's Annual Report on Form 10-K for the year ended
  December 31, 1998.
  
           (b)      The Registrant's Quarterly Reports on Form 10-Q for the
  quarters ended March 28, 1999, June 27, 1999 and September 26, 1999.
  
           (c)      Description of the Registrant's Common Stock contained in the
  Registrant's Registration Statement on Form 8-A (File No. 0-17297) and all
  amendments or reports filed for the purpose of updating such description.
  
           All other reports and other documents filed by the Registrant pursuant
  to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this
  Registration Statement and prior to the termination of this offering shall be
  incorporated by reference into this Registration Statement and shall be deemed
  to be a part of this Registration Statement from the date of filing of such
  reports and documents. Any statement contained herein or in a document
  incorporated by reference shall be deemed to be modified or superseded for
  purposes of this Registration Statement to the extent that a statement contained
  in this Registration Statement or in any other subsequently filed document which
  also is or is deemed to be incorporated by reference herein modifies or
  supersedes such statement. Any such statement so modified or superseded shall
  not be deemed, except as so modified or superseded, to constitute a part of this
  Registration Statement.
  
  Item 4.  DESCRIPTION OF SECURITIES.
  
           Not applicable.
  
  Item 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.
  
           Not applicable.
  
  Item 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.
  
           Section 145 of the Delaware General Corporation Law, as amended,
  provides that a corporation may indemnify any person who was or is a party or is
  threatened to be made a party to any threatened, pending or completed action,
  suit or proceeding, whether civil, criminal or investigative (other than an
  action by or in the right of the corporation) by reason of the fact that he or
  she is or was a director, officer, employee or agent of the corporation, or is
  or was serving at the request of the corporation as a director, officer,
  employee or agent of another corporation, partnership, joint venture, trust or
  other enterprise, against expenses (including attorneys' fees), judgments, fines
  and amounts paid in settlement actually and reasonably incurred by him or her in
  connection with such action, suit or proceeding if he or she acted in good faith
  and in a manner he or she reasonably believed to be in or not opposed to the
  best interests of the corporation, and, with respect to any criminal action or
  proceeding, had no reasonable cause to believe his or her conduct was unlawful.
  Section 145 further provides that a corporation similarly may indemnify any such
  person serving in any such capacity who was or is a party or is threatened to be
  made a party to any threatened, pending or completed action or suit by or in the
  right of the corporation to procure a judgment in its favor, against expenses
  (including attorneys' fees) actually and reasonably incurred in connection with
  the defense or settlement of such action or suit if he or she acted in good
  faith and in a manner he or she reasonably believed to be in or not opposed to
  the best interests of the corporation, except that no indemnification shall be
  made
  
  
  
                                         -3-
  
  
  <PAGE>   4
  
  
  
  in respect of any claim, issue or matter as to which such person shall have been
  adjudged to be liable to the corporation unless and only to the extent that the
  Delaware Court Chancery or such other court in which such action or suit was
  brought shall determine upon application that, despite the adjudication of
  liability but in view of all the circumstances of the case, such person is
  fairly and reasonably entitled to indemnity for such expenses which the Court of
  Chancery or such other court shall deem proper.
  
           Section 102(b)(7) of the Delaware General Corporation Law, as amended,
  permits a corporation to include in its certificate of incorporation a provision
  eliminating or limiting personal liability of a director to the corporation or
  its stockholders for monetary damages for breach of fiduciary duty as a
  director, provided that such provision 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 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 the Delaware General Corporation Law, as amended
  (relating to unlawful payment of dividends and unlawful stock purchase and
  redemption) or (iv) for any transaction from which the director derived an
  improper personal benefit.
  
           The Registrant's Restated Certificate of Incorporation provides that
  the Registrant's Directors shall not be liable to the Registrant or its
  stockholders for monetary damages for breach of fiduciary duty as a director,
  except to the extent that exculpation from liability is not permitted under
  Delaware General Corporate Law as in effect at the time such liability is
  determined. The Registrant's By-laws provide that the Registrant shall indemnify
  its directors and officers to the extent permitted by the General Corporate Law
  of the State of Delaware.
  
           The Registrant has obtained an insurance policy that insures its
  directors and officers against certain liabilities.
  
  Item 7.  EXEMPTION FROM REGISTRATION CLAIMED.
  
           Not applicable.
  
  Item 8.  EXHIBITS.
  
  Exhibit
  
  4.1      Restated Certificate of Incorporation of the Registrant (incorporated
           by reference to Exhibit 3.2 of the Registrant's Registration Form on
           S-1, File No. 33-24882).
  
  4.2      By-Laws of the Registrant, as amended (incorporated by reference to
           Exhibit 3.3 of the Registrant's Registration Statement on Form S-1,
           File No. 33-24882).
  
  5.1      Opinion of Ropes & Gray.
  
  23.1     Consent of Arthur Andersen LLP.
  
  23.2     Consent of Ropes & Gray (contained in the opinion filed as Exhibit 5.1
           to this Registration Statement).
  
  24       Powers of Attorney (included on the signature page of this Registration
           Statement under the caption "Power of Attorney").
  
  Item 9.  UNDERTAKINGS.
  
           (a)      The undersigned Registrant hereby undertakes:
  
  
  
                                         -4-
  
  
  <PAGE>   5
  
  
  
                    (1) To file, during any period in which offers or sales are
           being made, a post-effective amendment to this Registration Statement:
           (i) To include any prospectus required by Section 10(a)(3) of the
           Securities Act of 1933; (ii) To reflect in the prospectus any facts or
           events arising after the effective date of the Registration Statement
           (or the most recent post-effective amendment thereof) which,
           individually or in the aggregate, represent a fundamental change in the
           information set forth in the Registration Statement. Notwithstanding
           the foregoing, any increase or decrease in volume of securities offered
           (if the total dollar value of securities offered would not exceed that
           which was registered) and any deviation from the low or high end of the
           estimated maximum offering range may be reflected in the form of
           prospectus filed with the Commission pursuant to Rule 424(b) if, in the
           aggregate, the changes in volume and price represent no more than 20%
           change in the maximum aggregate offering price set forth in the
           "Calculation of Registration Fee" table in the effective Registration
           Statement; and (iii) To include any material information with respect
           to the plan of distribution not previously disclosed in the
           Registration Statement or any material change to such information in
           the Registration Statement; PROVIDED, HOWEVER, that paragraphs
           (a)(1)(i) and (a)(1)(ii) of this section do not apply if the
           Registration Statement is on Form S-3, Form S-8 or Form F-3, and the
           information required to be included in a post-effective amendment by
           those paragraphs is contained in periodic reports filed with or
           furnished to the Commission by the Registrant pursuant to Section 13 or
           Section 15(d) of the Securities Exchange Act of 1934 that are
           incorporated by reference in the Registration Statement.
  
                    (2) That, for the purpose of determining any liability under
           the Securities Act of 1933, each such post-effective amendment shall be
           deemed to be a new Registration Statement relating to the securities
           offered therein, and the offering of such securities at that time shall
           be deemed to be the initial bona fide offering thereof.
  
                    (3) To remove from registration by means of a post-effective
           amendment any of the securities being registered which remain unsold at
           the termination of the offering.
  
           (b)      The undersigned Registrant hereby undertakes that, for
  purposes of determining any liability under the Securities Act of 1933, each
  filing of the Registrant's annual report pursuant to section 13(a) or section
  15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing
  of an employee benefit plan's annual report pursuant to Section 15(d) of the
  Securities Exchange Act of 1934) that is incorporated by reference in the
  Registration Statement shall be deemed to be a new Registration Statement
  relating to the securities offered therein, and the offering of such securities
  at that time shall be deemed to be the initial bona fide offering thereof.
  
           (h)      Insofar as indemnification for liabilities arising under the
  Securities Act of 1933 may be permitted to directors, officers and controlling
  persons of the Registrant pursuant to the foregoing provisions, or otherwise,
  the Registrant has been advised that in the opinion of the Securities and
  Exchange Commission such indemnification is against public policy as expressed
  in the Act and is, therefore, unenforceable. In the event that a claim for
  indemnification against such liabilities (other than the payment by the
  Registrant of expenses incurred or paid by a director, officer or controlling
  person of the Registrant in the successful defense of any action, suit or
  proceeding) is asserted by such director, officer or controlling person in
  connection with the securities being registered, the Registrant will, unless in
  the opinion of its counsel the matter has been settled by controlling precedent,
  submit to a court of appropriate jurisdiction the question whether such
  indemnification by it is against public policy as expressed in the Act and will
  be governed by the final adjudication of such issue.
  
  
  
                                         -5-
  
  
  <PAGE>   6
  
  
  
  
                                     SIGNATURES
  
           Pursuant to the requirements of the Securities Act of 1933, the
  Registrant certifies that it has reasonable grounds to believe that it meets all
  of the requirements for filing on Form S-8 and has duly caused this Registration
  Statement on Form S-8 to be signed on its behalf by the undersigned, thereunto
  duly authorized, in North Billerica, Massachusetts, on this 10th day of January,
  2000.
  
                                      BTU INTERNATIONAL, INC.
  
  
  
                                      By /s/Paul J. Van der Wansem
                                         -----------------------------------------
                                         Paul J. Van der Wansem
                                         Chief Executive Officer
  
  
  
                                  POWER OF ATTORNEY
  
           Pursuant to the requirement of the Securities Act of 1933, this
  Registration Statement has been signed by the following persons in the
  capacities and on the dates indicated. Each person whose signature appears below
  hereby authorizes and constitutes Paul J. Van der Wansem and Thomas P. Kealy,
  and each of them singly, his true and lawful attorneys with full power to them,
  and each of them singly, to sign for him and in his name in the capacities
  indicated below any and all amendments (including post-effective amendments) to
  this Registration Statement and to file the same, with exhibits thereto, and
  other documents in connection therewith, and he hereby ratifies and confirms his
  signature as it may be signed by said attorneys, or any of them, to any and all
  such amendments.
  
  <TABLE>
  <CAPTION>
  Signature                                 Capacity in Which Signed                     Date
  ---------                                 ------------------------                     ----
  
  <S>                                 <C>                                          <C>
  /s/ Paul J. Van der Wansem          Chairman of the Board, Chief                 January 10, 2000
  ------------------------------      Executive Officer, President and
  Paul J. Van der Wansem              Director (principal executive officer)
  
  /s/ Thomas P. Kealy                 Vice President, Corporate Controller         January 10, 2000
  ------------------------------      and Chief Accounting Officer
  Thomas P. Kealy                     (principal financial and accounting
                                      officer)
  
  /s/ David A.B. Brown                Director                                     January 10, 2000
  ------------------------------
  David A.B. Brown
  
  /s/ J. Chuan Chu                    Director                                     January 10, 2000
  ------------------------------
  J. Chuan Chu
  
  /s/ Joseph F. Wrinn                 Director                                     January 10, 2000
  ------------------------------
  Joseph F. Wrinn
  </TABLE>
  
  
  
                                         -6-
  
  
  <PAGE>   7
  
  
  
  
                                    EXHIBIT INDEX
  
  
  Number                             Title of Exhibit
  ------                             ----------------
  
    4.1             Restated Certificate of Incorporation of the Registrant
                    (incorporated by reference to Exhibit 3.2 of the Registrant's
                    Registration Form on S-1, File No. 33-24882).
  
    4.2             By-Laws of the Registrant, as amended (incorporated by
                    reference to Exhibit 3.3 of the Registrant's Registration
                    Statement on Form S-1, File No. 33-24882).
  
    5.1             Opinion of Ropes & Gray.
  
   23.1             Consent of Arthur Andersen LLP.
  
   23.2             Consent of Ropes & Gray (contained in the opinion filed as
                    Exhibit 5.1 to this Registration Statement).
  
   24               Powers of Attorney (included on the signature page of this
                    Registration Statement under the caption "Power of Attorney").
  
  
  
                                         -7-
metadata_documents: [{"type": "S-8", "sequence": "1", "description": "BTU INTERNATIONAL, INC.", "secsgml_size_bytes": 19790}]
metadata_filer: {"company-data": {"conformed-name": "BTU INTERNATIONAL INC", "cik": "0000840883", "assigned-sic": "3559", "irs-number": "042781248", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-94713", "film-number": "507705"}, "business-address": {"street1": "23 ESQUIRE ROAD", "city": "NORTH BILLERICA", "state": "MA", "zip": "01862", "phone": "5086674111"}, "mail-address": {"street1": "23 ESQUIRE ROAD", "city": "NORTH BILLERICA", "state": "MA", "zip": "01862"}, "former-company": {"former-conformed-name": "BTU CORP", "date-changed": "19881109"}}
text: 1
  
      As filed with the Securities and Exchange Commission on January 14, 2000
                                                               FILE NO. 333-
  ================================================================================
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 20549
  
                                --------------------
  
                                      FORM S-8
                               REGISTRATION STATEMENT
                                        UNDER
                             THE SECURITIES ACT OF 1933
  
                                --------------------
  
                               BTU INTERNATIONAL, INC.
               (Exact name of registrant as specified in its charter)
  
                DELAWARE                                       04-2781248
      (State or other jurisdiction                          (I.R.S. Employer
    of incorporation or organization)                    Identification Number)
  
                                   23 ESQUIRE ROAD
                        NORTH BILLERICA, MASSACHUSETTS 01862
                                   (978) 667-4111
            (Address of principal executive offices, including zip code)
  
                 BTU INTERNATIONAL, INC. 1993 EQUITY INCENTIVE PLAN
      BTU INTERNATIONAL, INC. 1998 STOCK OPTION PLAN FOR NON-EMPLOYEE DIRECTORS
                              (Full title of the plans)
  
                             ---------------------------
  
                               PAUL J. VAN DER WANSEM
                        CHAIRMAN AND CHIEF EXECUTIVE OFFICER
                               BTU INTERNATIONAL, INC.
                        NORTH BILLERICA, MASSACHUSETTS 01862
                                   (978) 667-4111
                (Name and address, including zip code, and telephone
                 number, including area code, of agent for service)
  
                                --------------------
  
                           CALCULATION OF REGISTRATION FEE
  ===================================================================================================================
                                                Amount       Proposed maximum      Proposed maximum        Amount of
              Title of each class of             to be        offering price      aggregate offering     registration
            securities to be registered       registered         per share               price                fee
  -------------------------------------------------------------------------------------------------------------------
  Common Stock, $.01 par value               550,000 shs.       $5.4688(1)           $3,007,840(1)          $794.07
  
  ===================================================================================================================
  (1) FOR PURPOSES OF DETERMINING THE REGISTRATION FEE, THE MAXIMUM PER SHARE AND
  AGGREGATE OFFERING PRICES HAVE BEEN DETERMINED, PURSUANT TO RULE 457(h) OF THE
  SECURITIES ACT OF 1933, ON THE BASIS OF THE AVERAGE OF HIGH AND LOW PRICES OF
  THE COMMON STOCK REPORTED IN THE NASDAQ NATIONAL MARKET SYSTEM ON JANUARY 10,
  2000.
  
  ================================================================================
                              EXHIBIT INDEX ON PAGE 7;
                                 PAGE 1 OF 7 PAGES.
  2
  
  PART I
  
  INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS
  
  Note: The document(s) containing the information required by Item 1 of this Form
  S-8 and the statement of availability of information of BTU International, Inc.
  (the "Registrant"), and other information required by Item 2 of this Form will
  be sent or given to employees as specified by Rule 428 under the Securities Act
  of 1933, as amended (the "Securities Act"). In accordance with Rule 428 and the
  requirements of Part I of Form S-8, such documents are not being filed with the
  Securities and Exchange Commission (the "Commission") either as part of this
  Registration Statement or as prospectuses or prospectus supplements pursuant to
  Rule 424. The Registrant shall maintain a file of such documents in accordance
  with the provisions of Rule 428. Upon request, the Registrant shall furnish to
  the Commission or its staff a copy or copies of any or all of the documents
  included in such file.
  
                                         -2-
  3
  
  PART II
  
  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  Item 3.  INCORPORATION DOCUMENTS BY REFERENCE.
  
           The following documents previously filed by the Registrant with the
  Commission pursuant to the Securities Exchange Act of 1934, as amended (the
  "Exchange Act") are hereby incorporated by reference:
  
           (a)      The Registrant's Annual Report on Form 10-K for the year ended
  December 31, 1998.
  
           (b)      The Registrant's Quarterly Reports on Form 10-Q for the
  quarters ended March 28, 1999, June 27, 1999 and September 26, 1999.
  
           (c)      Description of the Registrant's Common Stock contained in the
  Registrant's Registration Statement on Form 8-A (File No. 0-17297) and all
  amendments or reports filed for the purpose of updating such description.
  
           All other reports and other documents filed by the Registrant pursuant
  to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this
  Registration Statement and prior to the termination of this offering shall be
  incorporated by reference into this Registration Statement and shall be deemed
  to be a part of this Registration Statement from the date of filing of such
  reports and documents. Any statement contained herein or in a document
  incorporated by reference shall be deemed to be modified or superseded for
  purposes of this Registration Statement to the extent that a statement contained
  in this Registration Statement or in any other subsequently filed document which
  also is or is deemed to be incorporated by reference herein modifies or
  supersedes such statement. Any such statement so modified or superseded shall
  not be deemed, except as so modified or superseded, to constitute a part of this
  Registration Statement.
  
  Item 4.  DESCRIPTION OF SECURITIES.
  
           Not applicable.
  
  Item 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.
  
           Not applicable.
  
  Item 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.
  
           Section 145 of the Delaware General Corporation Law, as amended,
  provides that a corporation may indemnify any person who was or is a party or is
  threatened to be made a party to any threatened, pending or completed action,
  suit or proceeding, whether civil, criminal or investigative (other than an
  action by or in the right of the corporation) by reason of the fact that he or
  she is or was a director, officer, employee or agent of the corporation, or is
  or was serving at the request of the corporation as a director, officer,
  employee or agent of another corporation, partnership, joint venture, trust or
  other enterprise, against expenses (including attorneys' fees), judgments, fines
  and amounts paid in settlement actually and reasonably incurred by him or her in
  connection with such action, suit or proceeding if he or she acted in good faith
  and in a manner he or she reasonably believed to be in or not opposed to the
  best interests of the corporation, and, with respect to any criminal action or
  proceeding, had no reasonable cause to believe his or her conduct was unlawful.
  Section 145 further provides that a corporation similarly may indemnify any such
  person serving in any such capacity who was or is a party or is threatened to be
  made a party to any threatened, pending or completed action or suit by or in the
  right of the corporation to procure a judgment in its favor, against expenses
  (including attorneys' fees) actually and reasonably incurred in connection with
  the defense or settlement of such action or suit if he or she acted in good
  faith and in a manner he or she reasonably believed to be in or not opposed to
  the best interests of the corporation, except that no indemnification shall be
  made
  
                                         -3-
  4
  
  in respect of any claim, issue or matter as to which such person shall have been
  adjudged to be liable to the corporation unless and only to the extent that the
  Delaware Court Chancery or such other court in which such action or suit was
  brought shall determine upon application that, despite the adjudication of
  liability but in view of all the circumstances of the case, such person is
  fairly and reasonably entitled to indemnity for such expenses which the Court of
  Chancery or such other court shall deem proper.
  
           Section 102(b)(7) of the Delaware General Corporation Law, as amended,
  permits a corporation to include in its certificate of incorporation a provision
  eliminating or limiting personal liability of a director to the corporation or
  its stockholders for monetary damages for breach of fiduciary duty as a
  director, provided that such provision 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 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 the Delaware General Corporation Law, as amended
  (relating to unlawful payment of dividends and unlawful stock purchase and
  redemption) or (iv) for any transaction from which the director derived an
  improper personal benefit.
  
           The Registrant's Restated Certificate of Incorporation provides that
  the Registrant's Directors shall not be liable to the Registrant or its
  stockholders for monetary damages for breach of fiduciary duty as a director,
  except to the extent that exculpation from liability is not permitted under
  Delaware General Corporate Law as in effect at the time such liability is
  determined. The Registrant's By-laws provide that the Registrant shall indemnify
  its directors and officers to the extent permitted by the General Corporate Law
  of the State of Delaware.
  
           The Registrant has obtained an insurance policy that insures its
  directors and officers against certain liabilities.
  
  Item 7.  EXEMPTION FROM REGISTRATION CLAIMED.
  
           Not applicable.
  
  Item 8.  EXHIBITS.
  
  Exhibit
  
  4.1      Restated Certificate of Incorporation of the Registrant (incorporated
           by reference to Exhibit 3.2 of the Registrant's Registration Form on
           S-1, File No. 33-24882).
  
  4.2      By-Laws of the Registrant, as amended (incorporated by reference to
           Exhibit 3.3 of the Registrant's Registration Statement on Form S-1,
           File No. 33-24882).
  
  5.1      Opinion of Ropes & Gray.
  
  23.1     Consent of Arthur Andersen LLP.
  
  23.2     Consent of Ropes & Gray (contained in the opinion filed as Exhibit 5.1
           to this Registration Statement).
  
  24       Powers of Attorney (included on the signature page of this Registration
           Statement under the caption "Power of Attorney").
  
  Item 9.  UNDERTAKINGS.
  
           (a)      The undersigned Registrant hereby undertakes:
  
                                         -4-
  5
  
                    (1) To file, during any period in which offers or sales are
           being made, a post-effective amendment to this Registration Statement:
           (i) To include any prospectus required by Section 10(a)(3) of the
           Securities Act of 1933; (ii) To reflect in the prospectus any facts or
           events arising after the effective date of the Registration Statement
           (or the most recent post-effective amendment thereof) which,
           individually or in the aggregate, represent a fundamental change in the
           information set forth in the Registration Statement. Notwithstanding
           the foregoing, any increase or decrease in volume of securities offered
           (if the total dollar value of securities offered would not exceed that
           which was registered) and any deviation from the low or high end of the
           estimated maximum offering range may be reflected in the form of
           prospectus filed with the Commission pursuant to Rule 424(b) if, in the
           aggregate, the changes in volume and price represent no more than 20%
           change in the maximum aggregate offering price set forth in the
           "Calculation of Registration Fee" table in the effective Registration
           Statement; and (iii) To include any material information with respect
           to the plan of distribution not previously disclosed in the
           Registration Statement or any material change to such information in
           the Registration Statement; PROVIDED, HOWEVER, that paragraphs
           (a)(1)(i) and (a)(1)(ii) of this section do not apply if the
           Registration Statement is on Form S-3, Form S-8 or Form F-3, and the
           information required to be included in a post-effective amendment by
           those paragraphs is contained in periodic reports filed with or
           furnished to the Commission by the Registrant pursuant to Section 13 or
           Section 15(d) of the Securities Exchange Act of 1934 that are
           incorporated by reference in the Registration Statement.
  
                    (2) That, for the purpose of determining any liability under
           the Securities Act of 1933, each such post-effective amendment shall be
           deemed to be a new Registration Statement relating to the securities
           offered therein, and the offering of such securities at that time shall
           be deemed to be the initial bona fide offering thereof.
  
                    (3) To remove from registration by means of a post-effective
           amendment any of the securities being registered which remain unsold at
           the termination of the offering.
  
           (b)      The undersigned Registrant hereby undertakes that, for
  purposes of determining any liability under the Securities Act of 1933, each
  filing of the Registrant's annual report pursuant to section 13(a) or section
  15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing
  of an employee benefit plan's annual report pursuant to Section 15(d) of the
  Securities Exchange Act of 1934) that is incorporated by reference in the
  Registration Statement shall be deemed to be a new Registration Statement
  relating to the securities offered therein, and the offering of such securities
  at that time shall be deemed to be the initial bona fide offering thereof.
  
           (h)      Insofar as indemnification for liabilities arising under the
  Securities Act of 1933 may be permitted to directors, officers and controlling
  persons of the Registrant pursuant to the foregoing provisions, or otherwise,
  the Registrant has been advised that in the opinion of the Securities and
  Exchange Commission such indemnification is against public policy as expressed
  in the Act and is, therefore, unenforceable. In the event that a claim for
  indemnification against such liabilities (other than the payment by the
  Registrant of expenses incurred or paid by a director, officer or controlling
  person of the Registrant in the successful defense of any action, suit or
  proceeding) is asserted by such director, officer or controlling person in
  connection with the securities being registered, the Registrant will, unless in
  the opinion of its counsel the matter has been settled by controlling precedent,
  submit to a court of appropriate jurisdiction the question whether such
  indemnification by it is against public policy as expressed in the Act and will
  be governed by the final adjudication of such issue.
  
                                         -5-
  6
  
                                     SIGNATURES
  
           Pursuant to the requirements of the Securities Act of 1933, the
  Registrant certifies that it has reasonable grounds to believe that it meets all
  of the requirements for filing on Form S-8 and has duly caused this Registration
  Statement on Form S-8 to be signed on its behalf by the undersigned, thereunto
  duly authorized, in North Billerica, Massachusetts, on this 10th day of January,
  2000.
  
                                      BTU INTERNATIONAL, INC.
  
                                      By /s/Paul J. Van der Wansem
                                         -----------------------------------------
                                         Paul J. Van der Wansem
                                         Chief Executive Officer
  
                                  POWER OF ATTORNEY
  
           Pursuant to the requirement of the Securities Act of 1933, this
  Registration Statement has been signed by the following persons in the
  capacities and on the dates indicated. Each person whose signature appears below
  hereby authorizes and constitutes Paul J. Van der Wansem and Thomas P. Kealy,
  and each of them singly, his true and lawful attorneys with full power to them,
  and each of them singly, to sign for him and in his name in the capacities
  indicated below any and all amendments (including post-effective amendments) to
  this Registration Statement and to file the same, with exhibits thereto, and
  other documents in connection therewith, and he hereby ratifies and confirms his
  signature as it may be signed by said attorneys, or any of them, to any and all
  such amendments.
  Signature                                 Capacity in Which Signed                     Date
  ---------                                 ------------------------                     ----
  /s/ Paul J. Van der Wansem          Chairman of the Board, Chief                 January 10, 2000
  ------------------------------      Executive Officer, President and
  Paul J. Van der Wansem              Director (principal executive officer)
  
  /s/ Thomas P. Kealy                 Vice President, Corporate Controller         January 10, 2000
  ------------------------------      and Chief Accounting Officer
  Thomas P. Kealy                     (principal financial and accounting
                                      officer)
  
  /s/ David A.B. Brown                Director                                     January 10, 2000
  ------------------------------
  David A.B. Brown
  
  /s/ J. Chuan Chu                    Director                                     January 10, 2000
  ------------------------------
  J. Chuan Chu
  
  /s/ Joseph F. Wrinn                 Director                                     January 10, 2000
  ------------------------------
  Joseph F. Wrinn
  -6-
  7
  
                                    EXHIBIT INDEX
  
  Number                             Title of Exhibit
  ------                             ----------------
  
    4.1             Restated Certificate of Incorporation of the Registrant
                    (incorporated by reference to Exhibit 3.2 of the Registrant's
                    Registration Form on S-1, File No. 33-24882).
  
    4.2             By-Laws of the Registrant, as amended (incorporated by
                    reference to Exhibit 3.3 of the Registrant's Registration
                    Statement on Form S-1, File No. 33-24882).
  
    5.1             Opinion of Ropes & Gray.
  
   23.1             Consent of Arthur Andersen LLP.
  
   23.2             Consent of Ropes & Gray (contained in the opinion filed as
                    Exhibit 5.1 to this Registration Statement).
  
   24               Powers of Attorney (included on the signature page of this
                    Registration Statement under the caption "Power of Attorney").
  
                                         -7-