Flexible epoxy-resin substrate based 1.2 kV SiC half bridge module with ultra-low parasitics and high functionality

To take full advantages of Wide Bandgap power semiconductor devices, breakthroughs on power module development are heavily explored nowadays. This paper introduces a 1.2kV SiC half bridge intelligent power module utilizing 80μm flexible epoxy-resin as substrates instead of traditional Direct-bonded Copper, for better thermal-stress management and lower cost. The investigation on the flexible epoxy-resin material indicates that it has low leakage current even at 250 °C, and high thermal conductivity up to 8 W/mK. No bonding wires are applied in the half bridge power module, instead, double-side solderable SiC MOSFET and diodes are fabricated and utilized for low parasitics and double-side cooling function. To further decrease the entire parasitic inductance on the power loop, a “Stack Structure” is proposed in this work to vertically connect highside and lowside switches with lower interconnection path than traditional power module technology. Simulation indicates that the parasitic inductance on the power loop is less than 1.5 nH. More functionality is achieved by integrating the main power stage with gate driver circuits. Digital isolations are also included in the half bridge module, together with a Low Dropout regulator to eliminate the numbers of auxiliary power supply required by the power module. The size of the entire module is about 35mm × 15mm ×7mm. Electrical simulations and measurements, including leakage current, parasitic extractions, device characteristics, verified that the designed module can work properly with no degradation on the SiC devices, with 12ns turn-off and 48ns turn-on at 800V bus voltage, and 0.63 mJ, 0.23 mJ as turn-on and turn-off loss, respectively.