A Low-Thermal-Stress Double-Sided Cooling Wire-Bondless Package Structure of SiC Power Modules for High-Temperature Applications

To leverage the outstanding high-temperature resistance of silicon carbide (SiC), theoretically up to 500 °C, conventional packaging materials, and structures have become inadequate to meet the requirements. The double-sided cooling (DSC) package structure can eliminate power bond wires, which are the reliability weak points in the conventional package, and has low parasitic inductance and low thermal resistance. However, it still faces severe high-temperature thermal stress, which hinders its high-temperature applications. Hence, this study proposes a high-temperature resistant DSC wire-bondless package structure called “Island,” which retains the conventional DSC package's excellent electrical and thermal performance and has lower thermal stress at high temperatures. The high-temperature stress concentration at the substrates' copper pattern gaps in the conventional DSC package is solved by splitting substrates. High-temperature co-fired ceramic (HTTC) substrates are introduced as monolithic spacers to provide adequate mechanical strength for the split-substrate structure. Besides, the island structure's thermal resistance is lower than the conventional DSC structure's because the HTCC-based interposer provides new heat conduction paths. Finally, a high-temperature-resistant SiC power module based on the island structure is designed and fabricated. Its static and dynamic characteristics were tested, and a prototype converter was assembled to verify its high-temperature continuous operation capacity.