Dear Sir or Madam:

I am looking for a polyimide backing for heating resistors with the following
functional requirements:

Must allow the etching of part of Constantan Foil or CuNi Foil
Must resist continuously to a temperature of > or equal to 250 degrees C
during 1000 hours during which time the bonding force must keep a min. peel
forces of 0.7 N/mm
Dielectrical value after 1000 hours at 250 degrees C: 1400 V

We have tried both Kapton and Upilex and both have exhibited a structural
deterioration and / or melting after the 1000 hours at 250 degrees C.

Any suggestions of an alternate material would be greatly appreciated.

Best regards,
John A. Kochanski
Product Development
Desmond International
Tel:  609-730-0445
Fax:  609-737-7333
e-mail: desmondint@aol.com