Thermo-mechanical analysis of 3-D multilayer structures for power electronic devices

An integrated simulation tool for multilayer stepped pyramidal structures, able to calculate the temperature distributions and thermal stresses at the interfaces between the layers and based on a semi-analytical mathematical strategy is presented. The core of the thermal solver is the analytical simulator DJOSER for power electronic devices. DJOSER is then integrated with a mechanical solver based on the finite element method. A new element is proposed whose geometry is defined by its mean surface and thickness, just like in a plate, and whose mechanical behaviour is fully three-dimensional, in the sense that the deformability in the direction orthogonal to the mean surface is taken into account. The dedicated finite element code developed for solving the equilibrium problem of structures made up of two or more superimposed plates subjected to thermal loads is applied to some two-layer samples made of silicon and copper. The comparisons with the results of standard finite element analyses using a large number of brick elements are presented and discussed.