<PAGE>

                                                                     Exhibit 4.9

                          SECOND AMENDED AND RESTATED
                               SECURITY AGREEMENT


          This SECOND AMENDED AND RESTATED SECURITY AGREEMENT, dated as of June
30, 1999, is between AEROVOX INCORPORATED, a Delaware corporation (the
"Borrower"), and BANKBOSTON, N.A., a national banking association with its
principal place of business at 100 Federal Street, Boston, Massachusetts 02110
(the "Bank").

(S) 1.    GRANT OF SECURITY INTEREST, ETC.
          --------------------------------

          The Borrower hereby grants to the Bank a continuing first priority
security interest in and lien on all accounts, contract rights, rights to the
payment of money, insurance refund claims and all other insurance claims and
proceeds, tort claims, all inventory (including, without limitation, raw
materials, work in progress, and finished goods inventory), chattel paper,
documents, instruments, general intangibles, tax refund claims, license fees,
patents, patent applications, trademarks, trademark applications, trade names,
copyrights, copyright applications, rights to sue and recover for past
infringements of patents trademarks and copyrights, computer programs, computer
software, customer lists, goodwill, engineering drawings, service marks, all
licenses, permits and agreements of any kind or nature pursuant to which the
Borrower possesses, uses, or has authority to possess or use property (whether
tangible or intangible) of others or others possess, use or have authority to
possess or use property (whether tangible or intangible) of the Borrower, all
recorded data of every kind or nature, including without limitation software,
writings, plans, specifications and schematics, of every kind and nature,
wherever located, whether now owned or hereafter acquired or arising, and all
proceeds and products thereof (hereinafter, the "Collateral").

(S) 2.    OBLIGATIONS SECURED
          -------------------

          The Collateral hereunder constitutes and will constitute continuing
security for all the Obligations of the Borrower to the Bank and any
institutional lender who becomes a participant in or holder of any of the
Obligations (as defined below) now existing or hereafter arising, direct or
indirect, absolute or contingent, due or to become due, matured or unmatured,
liquidated or unliquidated, arising by contract, operation of law or otherwise,
including without limitation all obligations now existing or hereafter arising
under the Second Amended and Restated Revolving Credit Agreement, dated June 30,
1999, among the Borrower and the Bank (the "Credit Agreement"), the promissory
note executed and delivered by the Borrower to the Bank in connection therewith
(the "Note"), or any of the other Loan Documents, in each case as such
instrument is modified, amended, supplemented or extended, and all obligations
of the Borrower to the Bank, arising out of any extension, refinancing or
refunding of any of the foregoing obligations (all the foregoing hereinafter
collectively referred to as the "Obligations").

(S) 3.    PRO-RATA SECURITY, APPLICATION OF PROCEEDS OF COLLATERAL
          --------------------------------------------------------
<PAGE>

                                                                     Exhibit 4.9


     All amounts owing with respect to the Obligations shall be secured pro rata
by the Collateral without distinction as to whether some Obligations or are then
due and payable and other Obligations are not then due and payable.  Upon any
realization upon the Collateral by the Bank, whether by receipt of insurance
proceeds pursuant to (S)4(e) or upon foreclosure and sale of all or part of the
Collateral pursuant to (S)6 or otherwise, the Borrower and the Bank agree that
the proceeds thereof shall be applied (a) first, to the payment of expenses
reasonably incurred with respect to maintenance and protection of the Collateral
pursuant to (S)4 and of expenses incurred pursuant to (S)10 with respect to the
sale of or realization upon, any of the Collateral or the perfection,
enforcement or protection of the rights of the Bank (including reasonable
attorney's fees and expenses of every kind, including, without limitation,
reasonable attorney's fees outstanding which constitute the Obligations; and (c)
third, to the payment of principal of the Obligations.  The Borrower and the
Bank agree that all amounts received with respect to any of the Obligations,
whether by realization on the Collateral or otherwise, shall be applied to the
payment of the Obligations in accordance with the provisions of this (S) 3.

(S)4.     REPRESENTATIONS AND COVENANTS OF THE BORROWER
          ---------------------------------------------

          (a)  Location of Chief Executive Office. The Borrower represents to
               the Bank that the location of the chief executive office of the
               Borrower and the location where the books and records of the
               Borrower are kept is as set forth in the Perfection Certificate
               attached as Exhibit A hereto. All property comprising a part of
               the Collateral is located at such addresses or at such other
               addresses given in Exhibit A hereto. The Borrower agrees that it
               will not change the location of its chief executive office or
               principal place of business or the location where its books and
               records are kept and will advise the Bank as to any change in the
               location (except for temporary changes in the normal and
               customary use thereof) of any property comprising a part of the
               Collateral.

          (b)  Ownership of Collateral.
               ------------------------

               (i)  The Borrower represents that it is the owner of the
                    Collateral free from any adverse lien, security interest or
                    encumbrance, except as permitted by (S)7.2 of the Credit
                    Agreement.

               (ii) Except for the security interests herein granted and except
                    as permitted in (S)7.2 of the Credit Agreement, the Borrower
                    shall be the owner of the Collateral free of any lien,
                    security interest or encumbrance and the Borrower shall
                    defend the same against all claims and demand of all persons
                    at any time claiming the same or any interest therein
                    adverse to the Bank. Except as otherwise permitted in (S)7.2
                    of the Credit Agreement, the Borrower shall not pledge,
                    mortgage or create or suffer to exist a security interest in
                    the Collateral in favor of any person other than the bank.
<PAGE>

                                                                     Exhibit 4.9


     (d)  Sale or Disposition of Collateral. Except for sales of inventory in
          ---------------------------------
          the ordinary course of business and sales or dispositions of other
          assets having an aggregate fair market value of less than $500,000 in
          any fiscal year, the Borrower will not sell or offer to sell or
          otherwise transfer the Collateral or any interest therein.


     (e)  Insurance. The Borrower shall have and maintain at all times with
          ---------
          respect to the Collateral such insurance as is required by the Credit
          Agreement, such insurance to be payable to the Borrower and to the
          Bank as their interests may appear. All policies of insurance shall
          provide for thirty day's written minimum cancellation notice to the
          Bank. In the event of failure to provide and maintain insurance as
          herein provided, after notice and demand, the Bank, at its option, may
          provide such insurance, and the Borrower hereby promises to pay to the
          Bank on demand the amount of any disbursements made by the Bank for
          such purpose. The Borrower shall furnish to the Bank certificates of
          other evidence satisfactory to the Bank of compliance with the
          foregoing insurance provisions. The Bank may act as attorney for the
          Borrower in obtaining, adjusting, settling and canceling such
          insurance and endorsing any drafts. Any amounts collected or received
          under any policies insuring equipment shall be applied by the Bank to
          the Obligations in accordance with the provisions of (S)3, or at the
          option of the Bank, the same may be released to the Borrower, but such
          application or release shall not cure or waive any default hereunder
          and no amount so released shall be deemed a payment on any Obligation
          secured hereby.

     (f)  Maintenance of Collateral. The Borrower will keep the Collateral in
          -------------------------
          good order and repair and will not use the same in violation of law or
          any policy of insurance thereon. The Bank may inspect the Collateral
          at any reasonable time, wherever located. Except as otherwise provided
          in (S)6.8 of the Credit Agreement, the Borrower will pay promptly when
          due all taxes and assessments upon the Collateral or for its use or
          operation or upon this agreement. In its discretion, the Bank may
          discharge taxes and other encumbrances at any time levied or placed on
          the Collateral which remain unpaid in violation of (S)6.8 of the
          Credit Agreement, make repairs thereof and pay any necessary filing
          fees. The Borrower agrees to reimburse the Bank on demand for any and
          all expenditures so made, and until paid the amount thereof shall be a
          debt secured by the Collateral. The Bank shall have no obligation to
          the Borrower to make any such expenditures, nor shall the making
          thereof relieve the Borrower of any default.

     (g)  Further Assurances By the Borrower. The Borrower agrees to execute and
          ----------------------------------
          deliver to the Bank from time to time at its request all documents and

<PAGE>

                                                                     Exhibit 4.9


               instruments, including financing statements, and to take all
               action as the Bank may reasonably deem necessary or proper to
               perfect or, otherwise protect the security interest and lien
               created hereby.

(S)5.  CONCERNING FINANCING STATEMENTS, ETC.
       -------------------------------------

          The Borrower shall do, make, execute and deliver all such additional
and further acts, things, deeds, assurances and instruments the Bank may
reasonably require more completely to vest in and assure to the Bank its rights
under or in any of the Collateral, including, without limitation, execution and
delivery of financing statements which the bank deems appropriate to perfect and
continue the security interests hereby granted; and the Borrower irrevocably
authorizes the Bank or its designee, at the expense of the Borrower, to file
such financing statements with respect hereto, with or without the signature of
the Borrower, as the Bank may deem appropriate, and appoints the Bank as the
attorney-in-fact of the Borrower to execute such financing statements.

(S)6.  REMEDIES.
       ---------

          Upon the occurrence of any Event of Default as defined in the Credit
Agreement and acceleration of the maturity of the Obligations to the fullest
extent permitted by applicable law:

          (a)  The Bank shall have, in addition to all other rights and remedies
               given it by any instrument or other agreement evidencing, or
               executed and delivered in connection with, any of the Obligations
               and otherwise allowed by law, the rights and remedies of a
               secured party under the Uniform Commercial Code as enacted in any
               jurisdiction in which the Collateral may be located, and with
               limiting the generality of the foregoing, the Bank may, without
               (to the fullest extent permitted by law) demand of performance or
               advertisement or notice of intention to sell or of time or place
               of sale or of redemption or other notice or demand whatsoever all
               of which are hereby expressly waived to the fullest extent
               permitted by law (except that the Bank shall give to the Borrower
               at least five (5) Business Days' notice of the time and place of
               any proposed sale or other disposition), sell at public or
               private sale or otherwise realize upon, in the City of Boston,
               Massachusetts, or elsewhere, the whole of from time to time any
               part of the Collateral in or upon which the Bank shall have a
               security interest or lien hereunder, or any interest which the
               Borrower may have therein, and after deducting from the proceeds
               of sale or other disposition of the Collateral all expenses
               (including all reasonable expenses for legal services, including
               without limitation reasonable allocated costs of staff counsel)
               as provided in (S)10, shall apply the residue of such proceeds
               toward the payment of the Obligations in accordance with (S)3 of
               this Agreement, the Borrower remaining liable for any deficiency
               remaining unpaid after such application. If notice of any sale or
               other disposition is required by law to be given to the Borrower,
               the
<PAGE>

                                                                     Exhibit 4.9


               Borrower hereby agrees that a notice given as provided herein
               shall be reasonable notice of such sale or disposition. The
               Borrower also agrees to assemble the Collateral at such place or
               places as the Bank reasonably designates by written notice. At
               such sale or other disposition, the Bank may itself, and any
               other Person or entity owed any Obligation may itself, purchase
               the whole or any part of the Collateral sold, free from any right
               of redemption on the part of the Borrower, which right is hereby
               waived and released to the fullest extent permitted by law.

          (b)  Furthermore, without limiting the generality of any of the rights
               and remedies conferred upon the Bank under (S)6(a) hereof, the
               Bank to the fullest extent permitted by law, may enter upon the
               premises of the Borrower, exclude the Borrower therefrom and take
               immediate possession of the Collateral, either personally or by
               means of a receiver appointed by a court therefor, using all
               necessary force to do so, and may, at its option, use, operate,
               manage and control the Collateral in any lawful manner and may
               collect and receive all rents, income, revenue, earnings, issues
               and profits therefrom, and may determine in its discretion, and
               any such moneys so collected or received by the Bank shall be
               applied to, or may be accumulated for application upon, the
               Obligations in accordance with this Agreement.

               The Bank agrees that it will give notice to the Borrower of any
               enforcement action taken by it pursuant to this (S)6 promptly
               after commencing such action.


(S)7.  MARSHALING.
       -----------

          The Bank shall not be required to marshal any present or future
security for (including but not limited to this Agreement and the Collateral
subject to the security interest created hereby), or guaranties of, the
Obligations, or to resort to such security or guaranties in any particular
order; and all of its rights hereunder and in respect of such securities and
guaranties shall be cumulative and in addition to all other rights, however
existing or arising. To the extent that it lawfully may, the Borrower hereby
agrees that it will not invoke any law relating to the marshaling of collateral
which might cause delay in or impede the enforcement of the Bank's rights under
this Agreement or under any other instrument evidencing any of the Obligations
under which any of the Obligations are outstanding or by which any of the
Obligations are secured or guaranteed, and to the extent that it lawfully may,
the Borrower hereby irrevocably waives the benefits of all such laws.


(S)8.  OBLIGATIONS NOT AFFECTED.
       -------------------------
<PAGE>

                                                                     Exhibit 4.9


          To the extent permitted by law, the obligations of the Borrower under
this Security Agreement shall remain in full force and effect without regard to,
and shall not be impaired by (a) any bankruptcy, insolvency, reorganization,
arrangement, readjustment, composition, liquidation or the like of the Borrower;
(b) any exercise or nonexercise, or any waiver, by the Bank of any right,
remedy, power or privilege under or in respect of any of the Obligations, or any
security therefor (including this Agreement); (c) any amendment to or
modification of this Agreement or any instrument evidencing any of the
Obligations or pursuant to which any of them were issued; (d) any amendment to
or modification of any instrument or agreement (other than this Agreement)
securing any of the Obligations; or (e) the taking of additional security for or
any guaranty of any of the Obligations or the release or discharge or
termination of any security or guaranty for any of the Obligations; and whether
or not the Borrower shall have notice or knowledge of any of the foregoing.

(S)9.  NO WAIVER.
       ----------

          No failure on the part of the Bank to exercise, and no delay in
exercising, any right, remedy or power hereunder shall operate as a waiver
thereof, nor shall any single or partial exercise by the Bank of any right,
remedy or power hereunder preclude any other or future exercise of any other
right, remedy or power. Each and every right, remedy and power hereby granted to
the Bank or the future holders of any of the Obligations or allowed to any of
them by law or other agreement, including without limitation the Credit
Agreement, the Note, or any other document evidencing security therefor, shall
be cumulative and not exclusive of any other, and subject to the provisions of
this Agreement, may be exercised by the Bank or the future holders of any of the
Obligations from time to time.

(S)10. EXPENSES.
       ---------

          The Borrower agrees to pay, on demand, all reasonable costs and
expenses (including reasonable attorneys' fees and expenses for legal services
of every kind, including without limitation reasonable allocated costs of staff
counsel) of the Bank incidental to the sale of, or realization upon, any of the
Collateral or other such reasonable expenses in any way relating to the
perfection, enforcement or protection of the rights of the Bank hereunder.  The
Bank may at any time apply to the payment of all such costs and expenses all
moneys of the Borrower or other proceeds arising from its possession or
disposition of all or any portion of the Collateral.

(S)11. CONSENTS, AMENDMENTS, WAIVERS, ETC.
       -----------------------------------

          Any term of this Agreement may be amended, and the performance or
observance by the Borrower of any term of this Agreement may be waived (either
generally or in a particular instance and either retroactively or prospectively)
only by a written instrument signed by the Borrower and the Bank.

(S)12.  GOVERNING LAW.
        --------------
<PAGE>

                                                                     Exhibit 4.9


          Except as otherwise required by the laws of any jurisdiction in which
any Collateral is located, this Agreement shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts.

(S)13.  PARTIES IN INTEREST.
        --------------------

          All Terms of this Agreement shall be binding upon and inure to the
benefit of and be enforceable by the respective successors and assigns of the
parties hereto, including without limitation any future holder of the Note and
any institutional lender who becomes a participant in or holder of any of the
Obligations, by amendment to the Credit Agreement or otherwise, provided that
the Borrower may not assign or transfer its rights hereunder without the prior
written consent of the Bank and the Bank may not assign or transfer its rights
hereunder unless the assignee confirms in writing its agreement to be bound by
the provisions of this Agreement.

(S)14.  TERMINATION.
        ------------

          Upon payment in full of the Obligations in accordance with their
terms, this Agreement shall terminate and the Borrower shall be entitled to the
return, at the expense of the Borrower, of such Collateral in the possession or
control of the Bank as has not theretofore been disposed of pursuant to the
provisions hereof.

(S)15.  NOTICES.
        --------

          Except as otherwise expressly provided herein, all notices and other
communications made or required to be given pursuant to this Agreement shall be
in writing and mailed by first-class mail, postage pre-paid, or sent by
telegraph, telecopy, or telex and confirmed by letter, addressed as follows:

          (a)  if to the Borrower:

               Aerovox Incorporated
               740 Belleville Avenue
               New Bedford, MA  02745
               Attention: Jeffrey Templer

          (b)  if to the Bank, at:

               BankBoston, N.A.
               100 Federal Street
               Boston, MA  02110
               Attention: Mark Evitts

or at such other address for notice as shall last have been furnished in writing
to the Person giving the notice.
<PAGE>

                                                                     Exhibit 4.9


     Any such notice or demand shall be deemed to have been duly given or made
and to have become effective (i) if delivered by hand to a responsible officer
of the party to which it is directed, at time of the receipt thereof by such
officer, (ii) if sent by registered or certified first-class mail, postage pre-
paid, five Business Days after the posting thereof and (iii) if sent by telex,
telecopy, or cable, at the time of dispatch thereof, if in normal business hours
in the state where received or otherwise at the opening of business on the
following Business Day.

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly
executed as an instrument under seal by their authorized representatives as of
June 30, 1999.


                                                  AEROVOX INCORPORATED

                                                  By: Robert D. Elliott
                                                  Title: President and CEO

                                                  BANKBOSTON, N.A.

                                                  By: Mark Evitts
                                                  Title: Vice President