Thermal Design of Power Semiconductor Modules for Mobile Communication System

Numerical Estimation of Module Thermal Resistance

Abstract

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 both steady state and transient analyses to determine the power module structure suitable for cell phones. We found that the thermal performance in periodic heating condition should be considered to reduce the number of module components and the production cost, even if the thermal resistance of the module was the most important design parameter for the module structure.