Aluminum nitride filled thermally conductive silicone composition

A thermally conductive composition comprising:

• a. a curable silicone composition comprising:
• i. a vinyldimethylsiloxy-terminated polydimethylpolysiloxane having a viscosity in a range of 30 to 400 milliPascal*seconds;
• ii. a silicon-hydride functional crosslinker;
• and
• iii. a hydrosilylation catalyst;
• where the molar ratio of silicon-hydride functionality from the crosslinker to vinyl functionality is in a range of 0.5:1 to 1:1;
• b. a filler treating agent comprising one or both of an alkyl trialkoxysilane and a mono-trialkoxysiloxy terminated dimethylpolysiloxane;
• c. a thermally conductive filler mix comprising:
• i. 40 weight-percent or more aluminum nitride fillers comprising a blend of spherical and irregular shaped aluminum nitride particles, both the spherical and irregular shaped particles having an average particle size of 30 micrometers or more and where the spherical aluminum nitride fillers with a particle size of 30 micrometers or more are present at a concentration of 40 to 60 weight-percent of the total weight of aluminum nitride fillers having a particle size of 30 micrometers or more;
• ii. 25 weight-percent to 35 weight-percent spherical aluminum oxide particles having an average particle size of one to 5 micrometers;
• iii. 10 weight-percent to 15 weight-percent of an additional thermally conductive filler having an average particle size of 0.1 to 0.5 micrometers;
• and
• iv. optionally, boron nitride fillers having an average particle size of more than 20 micrometers;
• where the weight-percent of each thermally conductive filler is relative to composition weight unless otherwise stated and the total amount of thermally conductive filler mix is 90-97 weight-percent of the composition weight.