Chip and Board Scale Transient Thermal Simulations for Power MOS Devices Reliability Analysis

The paper is a part of a larger study regarding reliability aspects of high power DMOS (Double-diffused MOS) transistors, as part of automotive integrated electronics. When submitted to high transient loads, the junction temperature of these devices suffers large excursion from ambient to 350°C, strongly influencing the reliability. Authors present in the paper the results of thermal transient analysis of a PCB (Printed Circuit Board) test structure containing 8 CERDIP (CERamic Dual In line Package) components on the board. The investigations are performed using FEM (Finite Element Method) analysis, the main results being the time evolutions of temperature in different locations of the board, including the chip active area. These time results are used as input data for thermal impedance calculations and for further simulations based on SPICE type programs.