Development of SiC power module for high-speed switching operation

In this work, SiC power module with sandwich structure is fabricated for high-speed switching operation at high temperature. A module structure of SiC power devices are sandwiched between two silicon nitride-active metal brazed copper circuit boards. To make a precise position and height control of the chip bonding, the top side (gate/source or anode pad side) of SiC power devices are flip-chip bonded to circuit electrodes using sub-micron Au particle with low temperature (250°C) and pressure-less sintering. The accuracy of the bonding position of chips was less than 10 μm and the accuracy of the height after bonding chips was less than 15 μm. The flip-chip bonding of SiC-JFET is successfully realized on the substrate without short or open failure electrically. Finally we joint the backside of the SiC-JFET (drain side) and the SiC-SBD (cathode side) to each circuit electrodes at once by means of reflow process with Au-12%Ge solder. Since the sandwitch module showed no fatigue afetr 500 times thermal cycle test between -40°C and 250°C and showed properly operation. The circuit operation of the module is confirmed by a double pulse-switching test.