Interfacing for heat sinks

Abstract

Withdrawal and dissipation of heat from an electronic solid-state device by an associated heat-sink structure are promoted by a relatively thin broad-area dielectric interfacing composed of dual filled layers of compliant silicone rubber in sandwiching relation to a porous glass-cloth carrier, one of the layers being pre-vulcanized and the other being subsequently cured and bonded in place once the composite interfacing has been applied to heat-sink surfaces adapted for abutment with the device for the intended heat transfer. The soft rubber interfacing offers good dielectric and insulating and voltage-breakdown characteristics even when well loaded with thermally-conductive oxides, and intimate voidless surface contacts and high-quality thermal matching are fostered both along abutting compliant surfaces of the pre-cured portion of the interfacing and along fully bonded surfaces of the portion cured in situ. Processing which makes such interfacing eminently practical and particularly advantageous to the user includes initial application of filled uncured rubber to one side of the sheet of the porous carrier, followed by its vulcanization and then by application of a further uncured amount to the opposite side of the carrier, with a protective peel-off plastic covering being used to facilitate handling and release-cutting of desired smaller wafer configurations from the large-area composite; uncured sides of the smaller peeled wafers are than mated with appropriate parts of heat sinks and cured, thereby producing heat sinks integrated with securely-bonded thermally-matching dielectric interfacing in readiness for unions with devices from which heat must be dissipated efficiently.