Thermal resistance evaluation by high-temperature transient thermal analysis method for SiC power modules

Abstract

Thermal resistance evaluation of silicon carbide (SiC) power module for high-temperature operation has been performed in order to define the precise thermal resistance in real package structure. Transient thermal analysis method using SiC-Schottky barrier diode (SBD) is applied to measure the thermal structure function in wide temperature range from 50°C to 250°C. The module structure consists of a SBD, a silicon nitride-active metal brazed copper (SiN-AMC) and Cu baseplate which are bonded each other by Gold Germanium (AuGe) solder. We found that it is difficult to define the thermal resistance components of the SiN-AMC and baseplate in the thermal structure function. The reference module structure without SiN-AMC is prepared for isolation of thermal resistances. The thermal resistance of SiN-AMC is successfully defined by comparing the structure functions without and with SiN-AMC. This phenomenon is attributed to thermal spreading effect in the high thermal conductivity material (Cu baseplate) based on present experiment. The thermal resistance in the module structure are successfully defined into 4 components. Furthermore, temperature dependency of the thermal resistances is also measured even in the middle of the package structure in wide temperature range from 50°C to 250°C.