Application of graphite nanoplatelet-based and nanoparticle composites to thermal interface materials

Thermal interface materials (TIMs) are of crucial importance in improving and enhancing heat transfer in electronic packages, particularly in high-density electronics at regions of exceedingly high temperatures. Commercial TIMs are generally composed of highly conductive particle fillers such as highly thermally conductive graphite and a matrix so that efficient heat transfer and good compliance of the interface material can be achieved during application. Two types of TIMs are tested based on the hybridisation of graphite nanoplatelets (GNPs) and nanoparticles (NPs). The hybrid materials are fabricated via screen printing process to ensure conformal uniformity of NPs spreading on the GNPs. The performance of fabricated materials such as temperature, applied pressure, heat flux and TIM thickness are concurrently tested in the temperature range 40-80°C and the pressure range 0-5.6 kgf/cm² using a standard TIM tester. The steady-state heat flow technique of American Society for Testing and Materials (ASTM) D5470-06 is fully adopted. For a thickness of 160 μm composite with three-layer GNPs and two-layer NPs, thermal conductivity is measured at ~0.2 W/m K. In addition, the measured trend in the change of specific thermal conductivity with pressure corresponds well with the data presented in the literature.