Effect of the cross-linking of polyorganosiloxane on highly thermally conductive silicone rubber's mechanical, dielectric, and thermally conductive properties and thermal reliability

With the rapid development of thermal management techniques, there is an urgent need for thermally conductive silicone rubber (TCSR) which has high softness, high electrical insulation, high thermal conductivity, and high reliability. Currently, the reliability problem has received little attention in the academic reports. Herein, the effect of the cross-linking of polyorganosiloxane on TCSR's mechanical, dielectric, and thermal properties and thermal reliability has been studied. It is found that the cross-linking has great impacts on the thermal reliability of mechanical and oil bleeding properties, and slight impacts on the thermal reliability of dielectric and thermally conductive properties. When the content of hydrogen-terminated silicone oil is 2–4 phr and the content of hydrogen-side silicone oil is 1.5–1.8 phr, the resultant TCSR has high properties, including high softness (Shore OO hardness 55−68), high compression ratio (20−40 % @ 20 psi), high dielectric strength (5.3−5.7 kV/mm), high thermal conductivity (4.3−4.8 W/mK), and high thermal reliability (less than 10 % variation for most properties after thermal aging). Possible mechanisms have been discussed.