Evaluation of Thermal Resistance Degradation of SiC Power Module Corresponding to Thermal Cycle Test

In this paper, we demonstrate that thermal degradation of silicon carbide (SiC) power modules corresponding to thermal cycles can be detected and tracked non-destructively by transient thermal analysis. The purpose of this evaluation is to analyze the distribution of the thermal resistance in the power module and to identify the structure deterioration part. As a target for evaluation power modules using a SiC-MOSFET for high-temperature operation were assembled with Zn-5Al eutectic solder. The junction to case thermal resistance was successfully evaluated as 0.85 K/W by using transient thermal analysis, and the thermal resistance of the Zn-5Al die-attachment was also evaluated as 0.13 K/W. A series of thermal cycle test between −40 and 250°C was conducted, and the power modules were evaluated their thermal resistance taken out from thermal cycle test machine at 100, 200, 500 and 1000 cycles. We identified the increase of thermal resistance each thermal cycle in specific modules. It was successfully shown that thermal resistance deterioration of SiC power module corresponding to thermal cycles can be traced non-destructively by this transient thermal analysis method.