Thermal Properties of Low-Temperature-Sintered Graphene/Nano-silver Paste for Insulated Gate Bipolar Transistor Packages

Although high-power devices have experienced rapid development, they still suffer from several limitations in terms of traditional interconnecting materials. This paper describes the preparation of nano-silver paste through liquid-phase chemical reduction using PVP/12-3-12 type gemini quaternary ammonium salt as the mixed stabilizing agent. The high-thermal-conductivity multilayer graphene was mixed into the nano-silver paste to improve the interfacial heat-transfer performance of power devices. The nano-silver paste was sintered at a low temperature (270°C), and its thermal properties were tested. The experimental results show that the thermal resistance of the sintered layers of different pastes decreases linearly with an increase in the loading of multilayer graphene under no-pressure sintering. When the loading of the multilayer graphene was 1%, the silver nanoparticles were adsorbed uniformly on the graphene nanosheets owing to the van der Waals force. Further, in comparison to pure nano-silver paste, the thermal resistance decreased by 60%. This shows that the uniform dispersion of multilayer graphene in the paste and its high thermal conductivity reduced the thermal resistance of the paste sintering layer, allowing the heat generated by the insulated gate bipolar transistor power chip to dissipate rapidly, improving the heat-transfer performance at the interface.