Document:

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                                                                   Exhibit 10.46

                       FIRST AMENDMENT TO CREDIT AGREEMENT

     AGREEMENT AND AMENDMENT made as of the 16th day of December, 1999, by and
between USTrust ("Lender") and BTU International, Inc. ("Borrower").

     WHEREAS, Lender and Borrower are parties to a Credit Agreement dated
September 5, 1997 (the "Credit Agreement") and certain other Loan Documents (as
defined in the Credit Agreement) under which Lender has made loans and extended
credit, form time to time, to Borrower;

     WHEREAS, the Borrowers have requested that Lender agree to amend the Credit
Agreement to, among other things, extend the Termination Date under the Credit
Agreement and modify the Debt Service Coverage Ratio;

     WHEREAS, Lender is prepared to agree to the foregoing amendments but only
on the terms and subject to the conditions set forth herein,

     NOW, THEREFORE, based on these premises, and in consideration of the mutual
promises herein contained, and other good and valuable consideration the receipt
and sufficiency of which are hereby acknowledged, Lender and Borrowers hereby
agree:

SECTION 1.  DEFINITIONS.

     Capitalized terms not defined herein shall have the meanings ascribed to
them in the Credit Agreement.

SECTION 2. AMENDMENTS TO CREDIT AGREEMENT. Borrower and Lender agree that the
Credit Agreement is amended as follows:

     2.1       Section 5.5(d) of the Credit Agreement is deleted and replaced
          with the following:

          "(d) Debt Service Coverage Ratio. Allow the ratio of (i) EBITDA of
          Borrower minus unfinanced Capital Expenditures minus cash income taxes
          paid that apply to the current year's Earnings minus Dividends and
          Distributions, to (ii) Borrower's interest expense plus Current
          Maturities of Long Term Debt, calculated retrospectively for the
          period of the immediately preceding four fiscal quarters, to be less
          than 1.20 to 1.00 on the last day of any fiscal quarter, provided that
          for purposes of determining the Debt Service Coverage Ratio,
          unfinanced Capital Expenditures shall not be deducted from the
          numerator of the ratio, so long as any Loans or Letters of Credit
          outstanding under this Agreement do not exceed $2,000,000 in the
          aggregate."

     2.2       Schedule I of the Credit Agreement is amended to delete the
          definition of "Termination Date" and to replace it with the following:

          "Termination Date" - the earlier of (a) April 30, 2004, and (b) the
          date the Lender's Commitment to make Loans is terminated pursuant to
          Section 7.2 of Article 7."

SECTION 3.  ACKNOWLEDGMENT OF OBLIGATIONS AND COLLATERAL.

     3.1  Borrower hereby acknowledges and agrees that it is unconditionally
          liable to Lender for the prompt and punctual performance of all
          Obligations under the Credit Agreement and other

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          Loan Documents, and that Borrower has no defenses, counterclaims or
          offsets with respect to the full payment and performance of all
          Obligations.

     3.2  Borrower hereby acknowledge and agree that Lender has and shall
          continue to have valid and enforceable and duly perfected security
          interests in and to all Collateral to secure the Obligations.

SECTION 4.  REPRESENTATIONS AND WARRANTIES.

     Borrower represents and warrants that each of the warranties and
representations contained in the Credit Agreement and each other Loan Document
is accurate and complete as of the date hereof.

SECTION 5.  CONTINUING EFFECT OF CREDIT AGREEMENT.

     Except as expressly set forth herein, or in any other documents to be
executed and delivered in connection herewith, the Loan Documents shall remain
in full force and effect in accordance with their terms.

SECTION 6.  MISCELLANEOUS.

     This Amendment, together with the Loan Documents, contains the entire
agreement of the parties with respect to the subject matter and supersedes all
prior negotiations, offers and discussions relating thereto. This Amendment may
be amended, modified, waived, discharges or terminated only by a writing signed
by the party to be charged with such amendment, modification, discharge or
termination. This Amendment shall be governed by Massachusetts law. This
Amendment may be executed by one or more of the parties in separate
counterparts, and all of such counterparts taken together shall be deemed to
constitute one and the same instrument.

     Executed under seal as of date set forth above.

                                           BTU INTERNATIONAL, INC.

                                           By:  T. Kealy
                                                --------
                                            Name:  T. Kealy
                                            Title  Vice President

                                           USTRUST

                                           By:  John E. Bukala
                                                --------------
                                            Name:  John E. Bukala
                                            Title  Vice President<PAGE>   1
                                                            Exhibit 10.47

                               Amendment No. 1 to
                       1988 Employee Stock Purchase Plan

       This amendment, dated as of June 15, 1989, amends the BTU International,
Inc. 1988 Employee Stock Purchase Plan (the "Plan"). Terms defined in the Plan
and not otherwise defined herein are used herein as so defined.

                                   WITNESSETH

         WHEREAS, the Board of Directors of BTU International, Inc. (the
"Company") has authorized the Plan;

         WHEREAS, the Board of Directors of the Company has reserved shares of
the Company's Common Stock to be issued in accordance with the Plan; and

         WHEREAS, pursuant to Section 17 of the Plan, the Board of Directors now
desires to amend certain provisions of the Plan in order to clarify the intent
of the Board of Directors in approving the Plan;

         NOW, THEREFORE, the Plan is hereby amended by striking the paragraph in
Section 12 of the Plan and by inserting in its place the words "INTENTIONALLY
OMITTED".

         IN WITNESS WHEREOF, the Board of Directors has caused this Amendment
No. 1 to the Plan to be filed with the Plan and has caused the Plan to be
amended hereby.<PAGE>   1
                                                                   Exhibit 10.48

                            BTU INTERNATIONAL, INC.

                       1988 Employee Stock Purchase Plan

                                   Amendment

         By unanimous resolution of the Board of Directors of BTU International,
Inc. (the "Company") dated February 20, 1991, which resolution was approved by
the shareholders of the Company on May 10, 1991, the number of shares of the
Company's Common Stock, $.01 par value per share, authorized for issuance under
the 1988 Employee Stock Purchase Plan (the "Plan") was increased by 200,000,
raising the total from 100,000 to 300,000 shares.

         As amended, Paragraph 2 of the Plan reads in its entirety as follows:

         "2. OPTIONS TO PURCHASE STOCK

                  Under the Plan, there is available an aggregate of not more
         than 300,000 shares of Stock (subject to adjustment as provided in
         Section 15) for sale pursuant to the exercise of options ("options")
         granted under the Plan to employees (within the meaning of Section
         3401(c) of the Internal Revenue Code of 1986 (the "Code")) of the
         Company ("employees") who meet the eligibility requirements set forth
         in Section 3 hereof ("eligible employees"). The Stock to be delivered
         upon exercise of options under the Plan may be either shares of BTU
         authorized but unissued Stock or shares of reacquired Stock, as the
         Board shall determine."<PAGE>   1
                                                                  Exhibit 10.49

                                AMENDMENT NO. 2
                            BTU INTERNATIONAL, INC.
                           1993 EQUITY INCENTIVE PLAN

         1. REFERENCE TO THE PLAN.

         Reference is hereby made to the BTU International, Inc. (the "Company")
1993 Equity Incentive Plan as amended by Amendment No. 1 to the BTU
International, Inc. 1993 Equity Incentive Plan (as amended, the "Plan"). Terms
defined in the Plan and not otherwise defined herein are used herein with the
meanings so defined.

         2. AMENDMENT TO THE PLAN.

         Subject to the approval of the stockholders of the Company, Section 4
of the Plan is hereby amended by deleting the first sentence thereof and
replacing it with the following sentence:

                  "Subject to the adjustment as provided in Section 8.6 below,
         the aggregate number of shares of Stock that may be delivered under the
         Plan will be 1,041,183."<PAGE>

                                                                     Exhibit 4.1

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED
(THE "ACT"), OR THE SECURITIES LAWS OF ANY STATE. THE SECURITIES MAY NOT BE
TRANSFERRED EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH
ACT AND APPLICABLE STATE SECURITIES LAWS OR PURSUANT TO AN APPLICABLE EXEMPTION
FROM THE REGISTRATION REQUIREMENTS OF SUCH ACT AND SUCH LAWS.

                                  BLUEFLY, INC.

                             SENIOR CONVERTIBLE NOTE

$
 ---------------
New York, New York                                                March 28, 2000

         FOR VALUE RECEIVED, the undersigned, BLUEFLY, INC., a New York
corporation (the "Payor" or the "Company"), promises to pay to the order of
_________ or its registered assign (the "Payee"), the principal sum of _________
DOLLARS ($_________) and interest on the outstanding principal balance as set
forth herein.

         1. Securities Purchase Agreement. This Senior Convertible Note is the
Senior Convertible Note issued pursuant to the Note and Warrant Purchase
Agreement, dated as of March 28, 2000, among the Payor, the Payee and _________
(the "Securities Purchase Agreement"). The Payee is entitled to the benefits of
(and subject to the obligations expressly contained in) this Senior Convertible
Note and the Securities Purchase Agreement and may enforce the agreements of the
Payor contained herein and therein and exercise the remedies provided for hereby
and thereby or otherwise available in respect hereto and thereto. Capitalized
terms used herein without definition shall have the meaning ascribed to such
terms in the Securities Purchase Agreement.

         2. Interest Rate; Payment.

            (a) The outstanding principal balance of this Senior Convertible
Note shall bear interest at an annual rate equal to 8% per annum, with interest
accruing, from and including the date hereof, on a cumulative, compounding
basis. Interest shall be computed on the basis of a 365- or 366-day year, as the
case may be, and the actual number of days elapsed, and shall be payable only
upon repayment of the principal on any Repayment Date (as defined below).

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            (b) The outstanding balance of any amount owed under this Senior
Convertible Note which is not paid when due shall bear interest at the rate of
2% per annum (the "Default Interest") above the rate that would otherwise be in
effect under this Senior Convertible Note with the Default Interest accruing,
from and including such due date, on a cumulative, compounding basis.

            (c) The outstanding principal and all accrued and unpaid interest
shall be paid in full no later than January 2, 2002 (the "Maturity Date"),
unless repaid earlier pursuant to the provisions of Section 3 (the date of any
payment pursuant to Section 3 and the Maturity Date, collectively referred to as
a "Repayment Date"). On a Repayment Date, the Payor shall pay the applicable
amount of principal and interest in lawful money of the United States of America
by wire or bank transfer of immediately available funds to an account designated
by the Payee in writing from time to time.

         (3) Prepayment.

            (a) Mandatory Prepayment.

                (i) Upon the occurrence of an Event of Default (as defined in
Section 5), the outstanding principal of and all accrued interest on this Senior
Convertible Note shall be accelerated and shall automatically become immediately
due and payable, without presentment, demand, protest or notice of any kind, all
of which are expressly waived by the Payor, notwithstanding anything contained
herein to the contrary.

                (ii) The Payee shall, at its sole option, have the right to
require the Payor to pay the outstanding principal of and all accrued interest
on this Senior Convertible Note upon the occurrence of any of the following
events: (1) Payor entering into an agreement to effectuate any sale or other
disposition of all or substantially all of its assets, in one transaction or in
a series of transactions, (2) the Company entering into an agreement to
effectuate any consolidation or merger into another entity, or (3) any sale of a
majority of the outstanding equity of the Company (or any other event that
constitutes a Change of Control of the Payor), in one transaction or in a series
of transactions. Immediately upon the occurrence of either of the events set
forth in clauses (1) or (2) above, or immediately upon obtaining knowledge that
any person has entered into an agreement to effectuate, the event set forth in
clause (3) above, the Payor shall give written notice of such event to the
Payee. Change of Control means any Person or "group" (within the meaning of
Section 13(d)(3) of the Exchange Act) other than a Principal Shareholder,
becoming the beneficial owner, directly or indirectly, of outstanding shares of
stock of the Company entitling such Person or Persons to exercise 50% or more of
the total votes entitled to be cast at a regular or special meeting, or by
action by written consent, of the stockholders of the Company in the election of
directors (the term "beneficial owner" shall be determined in accordance with
Rule 13d-3 of the Exchange Act).

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                (iii) Any mandatory prepayment under this Section 3(a) shall
include payment of reasonable costs and expenses, if any, associated with such
prepayment.

            (b) Optional Prepayment. The Payor may prepay all or any portion of
this Senior Convertible Note, at any time, by paying an amount equal to the
outstanding principal amount of this Senior Convertible Note, or the portion of
this Senior Convertible Note called for prepayment, together with interest
accrued and unpaid thereon to the date of prepayment and any other amounts due
under this Senior Convertible Note and the Securities Purchase Agreement,
without penalty or premium.

         4. Mandatory Conversion.

            (a) This Senior Convertible Note plus interest accrued and unpaid
thereon shall be automatically converted simultaneously with the Next Round
Financing (the "Triggering Event') into that number of fully paid and
non-assessable Next Round Securities which is equal to the quotient obtained by
dividing the then outstanding principal amount of this Senior Convertible Note
plus interest accrued and unpaid thereon to the date of conversion by the price
per Next Round Security paid in the Next Round Financing.

            (b) Promptly after the Triggering Event the Company shall deliver or
cause to be delivered to the holder of this Senior Convertible Note a
certificate or certificates representing the number of fully paid and
non-assessable shares of Next Round Securities into which this Senior
Convertible Note may be converted. Such conversion shall be deemed to have been
made simultaneously with the conclusion of the Next Round Financing, so that the
rights of the holder as a holder of this Senior Convertible Note shall cease
with respect to this Senior Convertible Note at such time (including, without
limitation, the right to receive the principal of this Senior Convertible Note
other than in the form of Next Round Securities), interest shall cease to accrue
hereon and the person or persons entitled to receive the Next Round Securities
deliverable upon conversion of this Senior Convertible Note shall be treated for
all purposes as having become the record holders of such Next Round Securities
at such time, and such conversion shall be at the conversion rate in effect at
such time.

            (c) The Company covenants that it will at all times reserve and keep
available out of its authorized Next Round Securities (at such time as such
Securities are authorized) solely for the purpose of issue or delivery upon
conversion of this Senior Convertible Note as herein provided, such number of
Next Round Securities as shall then be issuable or deliverable upon the
conversion of this Senior Convertible Note. The Company covenants that all Next
Round Securities which shall be so issuable or deliverable shall, when issued or
delivered, be duly and validly issued and fully paid and non-assessable.

<PAGE>

         5. Events of Default. An "Event of Default" shall occur if:

            (a) the Payor shall default in the payment of the principal of or
interest payable on this Senior Convertible Note, when and as the same shall
become due and payable, whether at maturity or at a date fixed for prepayment or
by acceleration or otherwise and such default with respect to the payment of
interest shall continue unremedied for two days;

            (b) the Payor shall fail to observe or perform any covenant or
agreement contained in this Senior Convertible Note, the Securities Purchase
Agreement or the Warrants and such failure shall continue for five business days
after Payor receives notice of such failure;

            (c) any representation, warranty, certification or statement made by
or on behalf of the Payor in this Senior Convertible Note or the Securities
Purchase Agreement or in any certificate, writing or other document delivered
pursuant hereto shall prove to have been incorrect in any material respect when
made;

            (d) an involuntary proceeding shall be commenced or an involuntary
petition shall be filed in a court of competent jurisdiction seeking (A) relief
in respect of Payor or of a substantial part of Payor's respective property or
assets, under Title 11 of the United States Code, as now constituted or
hereafter amended, or any other Federal or state bankruptcy, insolvency,
receivership or similar law (any such law, a "Bankruptcy Law"), (B) the
appointment of a receiver, trustee, custodian, sequestrator, conservator or
similar official for a substantial part of the property or assets of any Payor,
(C) the winding up or liquidation of any Payor; and such proceeding or petition
shall continue undismissed for 60 days, or an order or decree approving or
ordering any of the foregoing shall be entered;

            (e) the Payor shall (A) voluntarily commence any proceeding or file
any petition seeking relief under a Bankruptcy Law, (B) consent to the
institution of or the entry of an order for relief against it, or fail to
contest in a timely and appropriate manner, any proceeding or the filing of any
petition described in clause d, (C) apply for or consent to the appointment of a
receiver, trustee, custodian, sequestrator, conservator or similar official for
a substantial part of the property or assets of the Payor, (D) file an answer
admitting the material allegations of a petition filed against it in any such
proceeding, (E) make a general assignment for the benefit of creditors, (F)
become unable, admit in writing its inability or fail generally to pay its debts
as they become due or (G) take any action for the purpose of effecting any of
the foregoing;

            (f) one or more judgments or orders for the payment of money in
excess of $250,000 in the aggregate shall be rendered against the Payor and such
judgment(s) or order(s) shall continue unsatisfied and unstayed for a period of
30 days;

            (g) the Payor shall default in the payment of any principal,
interest or premium, or any observance or performance of any covenants or
agreements, with respect to indebtedness (excluding trade payables and other
indebtedness entered

<PAGE>

into in the ordinary course of business) in excess of $50,000 in the aggregate
for borrowed money or any obligation which is the substantive equivalent thereof
and such default shall continue for more than the period of grace, if any, or of
any such Indebtedness or obligation shall be declared due and payable prior to
the stated maturity thereof;

            (h) the Payor shall incur any indebtedness senior to this Senior
Convertible Note; or

            (i) any material provisions of this Senior Convertible Note, the
Securities Purchase Agreement, or the Warrants shall terminate or become void or
unenforceable or the Payor shall so assert in writing.

         6. Senior Status. The indebtedness evidenced by this Senior Convertible
Note is senior in right of payment to all other indebtedness of the Payor and
Payor agrees not to incur any indebtedness, which by its terms is senior in
right of payment to this Senior Convertible Note.

         7. Suits for Enforcement.

            (a) Upon the occurrence of any one or more Events of Default, the
holder of this Senior Convertible Note may proceed to protect and enforce its
rights by suit in equity, action at law or by other appropriate proceeding,
whether for the specific performance of any covenant or agreement contained in
the Securities Purchase Agreement or in aid of the exercise of any power granted
in this Senior Convertible Note, or may proceed to enforce the payment of this
Senior Convertible Note, or to enforce any other legal or equitable right it may
have as a holder of this Senior Convertible Note.

            (b) The holder of this Senior Convertible Note may direct the time,
method and place of conducting any proceeding for any remedy available to
itself.

            (c) In case of any Event of Default under the Securities Purchase
Agreement, the Payor will pay to the holder of this Senior Convertible Note such
amounts as shall be sufficient to cover the reasonable costs and expenses of
such holder due to such Event of Default, including without limitation, costs of
collection and reasonable fees, disbursements and other charges of counsel
incurred in connection with any action in which the holder prevails.

                  8. Notices. All notices, demands and other communications
provided for or permitted hereunder shall be made in the manner and to the
addresses set forth in Section 11.2 of the Securities Purchase Agreement.

                  9. Successors and Assigns. This Senior Convertible Note shall
inure to the benefit of and be binding upon the successors and permitted assigns
of the parties hereto. The Payor may not assign any of its rights under this
Senior Convertible Note without the prior written consent of Payee. The Payee
may assign all or a portion of their rights or obligations under this Senior
Convertible Note to an Affiliate without the prior written consent of the Payor.

<PAGE>

         10. Amendment and Waiver.

            (a) No failure or delay on the part of the Payor or Payee in
exercising any right, power or remedy hereunder shall operate as a waiver
thereof, nor shall any single or partial exercise of any such right, power or
remedy preclude any other or further exercise thereof or the exercise of any
other right, power or remedy. The remedies provided for herein are cumulative
and are not exclusive of any remedies that may be available to the Payor or
Payee at law, in equity or otherwise.

            (b) Any amendment, supplement or modification of or to any provision
of this Senior Convertible Note, any waiver of any provision of this Senior
Convertible Note and any consent to any departure by the Payor from the terms of
any provision of this Senior Convertible Note, shall be effective (i) only if it
is made or given in writing and signed by the Payor and the Payee and (ii) only
in the specific instance and for the specific purpose for which made or given.

         11. Headings. The headings in this Senior Convertible Note are for
convenience of reference only and shall not limit or otherwise affect the
meaning hereof.

         12. GOVERNING LAW. THIS SENIOR CONVERTIBLE NOTE SHALL BE GOVERNED BY
AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, WITHOUT
REGARD TO THE CONFLICTS OF LAW PRINCIPLES THEREOF.

         13. Costs and Expenses. The Payor hereby agrees to pay on demand all
reasonable out-of-pocket costs, fees, expenses, disbursements and other charges
(including but not limited to the fees, expenses, disbursements and other
charges of Paul, Weiss, Rifkind, Wharton & Garrison, special counsel to the
Payee) of the Payee arising in connection with any consent or waiver granted or
requested hereunder or in connection herewith, and any renegotiation, amendment,
work-out or settlements of this Senior Convertible Note or the indebtedness
arising hereunder.

         14. Waiver of Jury Trial and Setoff. The Payor hereby waives trial by
jury in any litigation in any court with respect to, in connection with, or
arising out of this Senior Convertible Note or any instrument or document
delivered pursuant to this Senior Convertible Note, or the validity, protection,
interpretation, collection or enforcement thereof, or any other claim or dispute
howsoever arising, between any Payor and the Payee; and the Payor hereby waives
the right to interpose any setoff or counterclaim or cross-claim in connection
with any such litigation, irrespective of the nature of such setoff,
counterclaim or cross-claim except to the extent that the failure so to assert
any such setoff, counterclaim or cross-claim would permanently preclude the
prosecution of the same.

         15. Consent to Jurisdiction. The Payor hereby irrevocably consents to
the nonexclusive jurisdiction of the courts of the State of New York and of any
federal court located in such State in connection with any action or proceeding
arising out of or

<PAGE>

relating to this Senior Convertible Note or any document or instrument delivered
pursuant to this Agreement.

         16. Severability. If any one or more of the provisions contained
herein, or the application thereof in any circumstance, is held invalid, illegal
or unenforceable in any respect for any reason, the validity, legality and
enforceability of any such provisions hereof shall not be in any way impaired,
unless the provisions held invalid, illegal or unenforceable shall substantially
impair the benefits of the remaining provisions hereof.

         17. Entire Agreement. This Senior Convertible Note, the Warrants and
the Securities Purchase Agreement is intended by the parties as a final
expression of their agreement and intended to be a complete and exclusive
statement of the agreement and understanding of the parties hereto in respect of
the subject matter hereof. There are no restrictions, promises, warranties or
undertakings, other than those set forth or referred to herein. This Senior
Convertible Note supersedes all prior agreements and understandings between the
parties with respect to such subject matter.

         18. Further Assurances. The Payor shall execute such documents and
perform such further acts (including, without limitation, obtaining any
consents, exemptions, authorizations or other actions by, or giving any notices
to, or making any filings with, any governmental authority or any other Person)
as may be reasonably required or desirable to carry out or to perform the
provisions of this Senior Convertible Note.

                                       BLUEFLY, INC.

                                       By:
                                           ----------------------------
                                           Name:
                                           Title:

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