Thermal Design and Characterization of High Power SiC Inverter with Low Profile and Enhanced Thermal Performance

A single phase high power package is designed and developed in this study. The developed power package achieves significant thermal performance improvement as compared with the conventional wire-bonded power package. The improvement is attributed to two features of the package design. Firstly, the SiC chips are embedded into the active metal brazed (AMB) substrates with specially designed cavities, as such the heat transfer path from the embedded SiC chips to the liquid cooled heat sink attached to the bottom side of AMB substrate is shortened. Moreover, customized copper clips are introduced as the interconnections between the SiC chips and top metal layer of the substrate in the same level, and the top surface of the power package remains flat. As such another heat sink can be added to the top side of the package to improve the power package thermal performance further by implementing this double side cooling (DSC) Scheme. Results of the modeling and simulation show that the proposed package junction to case thermal resistance is ~50% less than the junction to case thermal resistance of the conventional wire bonded power package with same size and same power rate. Further utilizing two heat sinks on the both sides of the proposed power package which is not suitable to the conventional wire bonded power package, the junction to case thermal resistance of the proposed power package reduces another 20%. In addition, the effects of the core and metal layers of the AMB substrate on the thermal resistance of the proposed power package are investigated systematically. Finally, the thermally optimized power package is fabricated and assembled. Thermal characterization has been conducted and thermal performance of the developed power package has been evaluated. The simulation results and characterization results match well with each other.