Hybrid Nanocomposite Thermal Interface Materials: The Thermal Conductivity and the Packing Density

We have investigated a novel hybrid nanocomposite thermal interface material (TIM) that consists of silver nanoparticles (AgNPs), silver nanofiakes (AgNFs), and copper microparticles (CuMPs). Continuous metallic network form while AgNPs and AgNFs fuse to join bigger CuMPs upon hot compression, resulting in superior thermal and mechanical performances. The assembly temperature is as low as 125 degrees C due to the size effect of silver nanoparticulates. The thermal conductivity, k, of the hybrid nanocomposite TIMs is found to be in the range of 15-140 W/mK, exceeding best-performing commerical thermal greases, while comparable to high-end solder TIMs. The dependence o f k on the solid packing density and the volume fraction of voids is discussed through comparing to model predictions.