A Direct Bond Fabrication Process for Compact GaN Intelligent Power Modules on Liquid Coolers for EV Applications

Compact liquid cooled gallium nitride (GaN) intelligent power modules (IPMs) are fabricated using direct bonding methods. A half bridge module with 15 A GaN high electron mobility transistors (HEMTs) is flip-chip bonded on active metal brazed (AMB) substrates using pressureless nanosilver sintering. The AMB substrates are pre-brazed on a copper liquid cooler. The geometries of the AMB substrates and the GaN IPMs are determined based on thermal simulations using finite element analysis (FEA). The prototype GaN IPMs are tested in a buck converter configuration. The module temperatures are below 35 degrees C for up to 35 W of output power. The proposed process flow offers a simple IPM packaging solution to power semiconductor companies using prefabricated liquid coolers with brazed AMB substrates from automotive parts manufacturers.