Development of high-thermal conductive Ag@diamond composite sintering paste and its application in power modules

Diamond, known for its exceptional thermal conductivity and low coefficient of thermal expansion, offers significant advantages as a filler in composite solder pastes for high-power electronic devices. This study investigates Ag@diamond composite sintering pastes with varying diamond doping concentrations (2%, 5%, 8%, and 10%). The Ag@5%diamond paste achieved the highest thermal conductivity of 96.59 W/m K, a 43.05% increase compared to undoped paste. The shear strength was highest for Ag@2%diamond at 92.25 MPa. However, at higher doping levels (8% and 10%), both thermal conductivity and shear strength decreased due to diamond particle agglomeration. Microstructural analysis showed that agglomeration weakened the bonding, leading to interfacial detachment during fracture. A finite element analysis-based silicon carbide chip packaging model demonstrated a 3.09 °C reduction in maximum junction temperature compared to the sintered pure Ag. These results suggest that Ag@diamond composite sintering pastes offer an optimal balance of high shear strength and enhanced thermal conductivity, making them promising for thermal management in high-power devices.