1


                                                                     Exhibit 5.1


                                   June 29, 2001



Sheldahl, Inc.
1150 Sheldahl Road
Northfield, Minnesota  55057

         Re:      Opinion of Counsel as to Legality of 2,306,588 Shares of
                  Common Stock to be registered under the Securities Act of 1933

Ladies and Gentlemen:

             This opinion is furnished in connection with the registration under
the Securities Act of 1933 on Form S-8 of 2,306,588 shares of Common Stock,
$0.25 par value, of Sheldahl, Inc. (the "Company") offered to officers, other
key employees and non-employee directors pursuant to the Sheldahl, Inc. 1994
Stock Plan (the "Plan").

             We advise you that it is our opinion, based on our familiarity with
the affairs of the Company and upon our examination of pertinent documents, that
the 2,306,588 shares of Common Stock to be issued by the Company under the Plan,
will, when paid for and issued, be validly issued and lawfully outstanding,
fully paid and nonassessable shares of Common Stock of the Company.

             The undersigned hereby consent to the filing of this opinion with
the Securities and Exchange Commission as an Exhibit to the Registration
Statement with respect to said shares of Common Stock under the Securities Act
of 1933.

                                       Very truly yours,

                                       LINDQUIST & VENNUM P.L.L.P.

                                       /s/ Lindquist & Vennum P.L.L.P.




                                       20