Method for Removal of SYLGARD Top Seal
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
SYLGARD* top seal is applied over MC/CERMET substrates to protect the resistor from moisture. Occasionally, it is necessary to remove the Sylgard to perform failure analysis. A method of removal which uses liquid FREON** is described in the following. Any source of liquid FREON (a chlorofluorocarbon, designated as refrigerant-12) may be used. The liquid refrigerant-12 is sprayed onto the surface of the substrate containing the SYLGARD coating. The liquid stream cools the SYLGARD, causing it to become more viscous, and the force of the spray readily removes the SYLGARD. It is necessary to spray from several directions to assure complete removal of the SYLGARD from around the pin heads and solder. The substrate is warmed with a hot air gun to remove the frost that forms when spraying is stopped.