Silver-copper hybrid nanocomposite thermal interface materials for power electronic device packaging
摘要
Thermal interface materials (TIMs) play a crucial role in the thermal management of power electronic devices. In this study, a new class of silver-copper micro-nano hybrid composite pastes (AgCuMNHs) was developed as die-attach TIMs by exploiting the size and shape characteristics of copper microparticles (CuMPs), silver nanoflakes (AgNFs), and silver nanoparticles (AgNPs). The AgCuMNHs form Ag-Cu hybrid nanocomposites through low-temperature sintering achieved a high thermal conductivity of up to 330.0 W/(m·K), with a corresponding electrical conductivity of 5.6 × 107 S/m, under the optimized processing conditions of 220 ℃ and 0.7 MPa. It was found that the solvent choices play a significant role in the paste formulation since the polarity of solvent would highly affect the disperse and distribution of the silver nanoparticles and nanoflakes in the pastes, which dictated the degree of sintering in the hybrid nanocomposites and hence showed large differences in material thermal and electrical conductivities. To further validate the AgCuMNH as high performance TIMs for power electronic device packaging, they were used as the die-attach pastes for a model LED chip packaging structure. The effective die-attach thermal resistance of the AgCuMNH-based device was 0.56 K/W. Compared with the best commercially available low-temperature sintered silver paste from Kyocera (CT2700R7S), whose effective die-attach thermal resistance in the same device was measured to be 1.00 K/W in the parallel tests, the AgCuMNH composites demonstrated a more than 40% improvement in performance as the TIMs for packaged devices.