Thermal and electrical reliability analysis of TO-247 for bonding method, substrate structure and heat dissipation bonding material

Abstract

In this study, a 1700V/58A SiC MOSFET was used as the TO-247 module instead of the existing Si TO-247 module to analyze the thermal and electrical characteristics of a high-power module. The TO-247 module was manufactured to measure the electrical characteristics under thermal cycle testing (−40 to 125°C). The substrates used in the fabrication were standard TO-247 substrates, AlN DBC with high thermal conductivity, and Si3N4 AMB with high mechanical properties. The PbSn preform of the conventional solder base and a highly reliable Ag sintering paste were used as the bonding materials. For interconnection, wire bonding, which is most used in modules, and Cu clips attached using heterogeneous bonding materials were used in the TO-247 module. A total of 100 cycles were carried out, and Trr and RDS(on) were measured every 50 cycles to assess the electrical characteristics. The thermal analysis of the maximum temperature difference between the substrates, bonding materials, and interconnections was performed by adding a Cu clip bonding. The electrical properties were measured during the thermal cycling. all samples performed better than the 1700V/58A SiC MOSFET datasheet and operated normally after 100 cycles. Additionally, the maximum temperature difference between the Al wire and Cu clip bonding was not significant in the standard TO-247 module. However, using Cu clip bonding is more effective in reducing temperature when high heat is generated using substrates with low thermal conductivity.