THERMALLY CONDUCTIVE ORGANOSILOXANE COMPOSITIONS

The combination of known thermally conductive fillers having an average particle size of from about 10 to about 100 microns with aluminum nitride having an average particle size of less than one micron improves the thermal conductivity of organosiloxane compositions. The thermal conductivity values achieved using this combination of fillers is higher than can be achieved using the maximum loading of either filler alone that can be present without adversely affecting the ability of the organosiloxane composition to cure or to serve as useful coatings and encapsulants for electronic solid state devices and other substrates.