Noncured Graphene Thermal Interface Materials for High-Power Electronics: Minimizing the Thermal Contact Resistance

We report on experimental investigation of thermal contact resistance, R-C, of the noncuring graphene thermal interface materials with the surfaces characterized by different degree of roughness, S-q. It is found that the thermal contact resistance depends on the graphene loading, xi, non-monotonically, achieving its minimum at the loading fraction of xi similar to 15 wt%. Decreasing the surface roughness by S-q similar to 1 mu m results in approximately the factor of x2 decrease in the thermal contact resistance for this graphene loading. The obtained dependences of the thermal conductivity, K-TIM, thermal contact resistance, R-C, and the total thermal resistance of the thermal interface material layer on xi and S-q can be utilized for optimization of the loading fraction of graphene for specific materials and roughness of the connecting surfaces. Our results are important for the thermal management of high-power-density electronics implemented with diamond and other wide-band-gap semiconductors.