Prediction of electronic component-board transient conjugate heat transfer

Abstract

Numerical analysis of electronic component transient heat transfer has generally been confined to nonconjugate methods. This study discusses the need for conjugate (conduction/convection) analysis, both for component temperature and thermo-mechanical behavior prediction in operational, assembly and reliability qualification environments. The capability of computational fluid dynamics (CFD) analysis to predict component transient conjugate heat transfer is investigated using an industry-standard CFD code for the thermal analysis of electronics. The test cases are based on a single board-mounted, 160-lead plastic quad flat pack (PQFP) component, subjected to dynamic power- and air temperature conditions, in still-air and forced airflows. Benchmark criteria are based on component junction temperature and component-printed circuit board (PCB) surface temperature, measured using thermal test dies and infrared thermography respectively. Using both nominal component/PCB geometry dimensions and material properties, component junction temperature is found to be accurately predicted. The results suggest that CFD analysis could play an important role in providing critical boundary conditions for component electrical performance and thermo-mechanical behavior analyses, optimizing accelerated life test (ALT) parameters and convective assembly processes.