Thermal modeling and characterization of SiC power module under both air cooling and liquid cooling conditions

Silicon carbide based power modules are receiving more attention due to their performance advantages over traditional silicon power modules. The demanding operation requirements such as higher power output, faster switching speed, and higher working temperature present great thermal management challenge, which necessitates the analysis and characterization of various thermal interface and bonding layers and cooling technologies. In the present work, a new 3-phase SiC DMOSFET power module is developed with six SiC dies and copper clips, and corresponding cooling technologies are examined under liquid cooling and air cooling conditions. Different thermal assembly layers including flip chip attach, clip attach, direct bonding copper (DBC), heat sink thermal interface materials are examined. It is found that the die attach and clip attach, formed with sintering silver, have the most significant effects on the power module thermal performance than the outer heat sink thermal interface materials. In addition, the die metallization size should be enlarged as much as possible to minimize the internal thermal resistance at flip chip bonding layer. A module thermal resistance is found to be 0.184 K/W under dual side liquid cooling and 0.254 K/W under air cooling condition. A liquid cooled heat sink is fabricated with ceramic based copper fins. A power cycling simulation is also conducted, which indicate that a junction temperature change (ΔT) of 150°C could be attained with 1.5S/1.5S on/off condition and 960 W power input.