A compact insulated gate bipolar transistor (IGBT) module with low thermal resistance and direct liquid cooling, system has been developed to contribute to reducing the size of user systems. Thermal fl uid simulations were used to optimize the liquid cooling fi n shape. Square pin fi ns were selected because of their overall outstanding performance, including heat dissipation performance, cooling liquid fl ow velocity, and pressure loss. Under optimized liquid fl ow conditions, measured values of chip temperature were within 2% of simulation values, confi rming the accuracy of the simulations. From these results, this IGBT module for direct liquid cooling realizes a 30% reduction in thermal resistance and allow a 40% reduction in size compared to the conventional confi guration.