Difficulty and solution in transient thermal resistance measurement for wide band gap power semiconductor device

The junction temperature of power device must be suppressed lower than maximum operating temperature to avoid device failure. The heat radiation performance of packaged power device in power module is expressed by thermal resistance from junction to ambient. The thermal capacitance of component in package have an effect on transient temperature elevation resulting from over current and fault current. Then, the thermal performance should be expressed as a combination of thermal resistance and capacitance, which is expressed as structure function. The structure function is identified from measured transient thermal resistance. The conventional transient thermal resistance characterization method, which is standardized as JEDEC JESD51-1 is established for Si device. This paper indicates that the characterization setup for conventional standardized method cannot correctly estimate transient junction temperature for wide band gap power device; e.g. SiC MOSFET and GaN GIT. Therefore, this paper develops setup to accurately estimate transient junction temperature for transient thermal resistance characterization of SiC MOSFET and GaN GIT. The developed setup utilizes the structural feature of these power device. The measured transient thermal resistance with developed setup makes it possible to extract structure function of packaged SiC MOSFET and GaN GIT. The extracted structure function is useful in designing and validating thermal design of power electronics system with packaged wide band gap power semiconductor device.