Finite element simulation of thermal fatigue in multilayer structures: thermal and mechanical approach

The large difference in thermal expansion between dissimilar materials pres ent in any electronic package is the source of a major problem to be solved in order to achieve improved reliability. In this paper, simplified therma l and mechanical finite element models are presented for the analysis of th ermal stress derived problems. The problems investigated here include, ther mal stresses in adhesive backbonds in surface mounted structures and effect s of thermal fatigue in soft solder interfaces in conventional power module s such as insulated gate bipolar transistors modules. Full multidimensional mechanical and thermal analysis is made by using the commercial engine:rin g computer package ANSYS. Validation of the thermal simulation is achieved by comparison between simulation and experimental test results, whereas a s imple analytical model based upon the lap joint theory is used to verify th e structural simulation. (C) 2001 Elsevier Science Ltd. All rights reserved .