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

The large difference in thermal expansion between dissimilar materials present in any electronic package is the source of a major problem to be solved in order to achieve improved reliability. In this paper, simplified thermal and mechanical finite element models are presented for the analysis of thermal stress derived problems. The problems investigated here include, thermal stresses in adhesive backbonds in surface mounted structures and effects of thermal fatigue in soft solder interfaces in conventional power modules such as insulated gate bipolar transistors modules. Full multi-dimensional mechanical and thermal analysis is made by using the commercial engineering computer package . Validation of the thermal simulation is achieved by comparison between simulation and experimental test results, whereas a simple analytical model based upon the lap joint theory is used to verify the structural simulation.