Thermal Design of Power Semiconductor Modules for Mobile Communication System (Optimization of Distance between Heat-dissipating Cells)

We will describe the thermal performance of power semiconductor module, which consists of heterojunction bipolar transistors (HBTs), for mobile communication systems. We calculate the thermal resistance between the HBT fingers and the bottom surface of a multi-layer circuit board using a finite element method (FEM). We applied a steady state analysis to optimize the distance between each HBT finger and reduce the thermal resistance of the module. We found that the thermal resistance of the unequally spaced finger layout module could be 10% lower than that of the equally spaced finger layout module.