Thermal characterizations of Cu nanoparticle joints for power semiconductor devices

• We found a way to measure thermal conductivity of joint at steady heat conduction.
• The Cu nanoparticle joint showed the much higher thermal conductivity than solders.
• The Cu nanoparticle joint was not deteriorated for 3000 power cycles up to 200 °C.

The Cu nanoparticles capped by fatty acids and amines were synthesized. The thermal resistances of the Cu nanoparticle joints between Al2O3 heater chips and Cu–65Mo baseplates were measured. The thermal conductivities of the Cu nanoparticle joints were estimated from the thermal resistances using finite element method. The Cu nanoparticle joint exhibited the much higher thermal conductivity (>125 W/m K) than ordinary solders. The thermal resistance of the Cu nanoparticle joint was almost constant after the power cycling for 3000 cycles up to 200 °C even though that of the solder joint was rapidly increased.