Thermo-Mechanical Constraints for Packaging of Diamond Components

In this work a Finite Element Simulation thermal and mechanical study of a power SOT-227 package with a diamond die is performed in order to assess the impact of its mechanical properties when compared to the standard silicon dies. Furthermore, the simulations are carried using silver sintering as die-attach material, and different conditions and parameters that affect its mechanical behaviour are explained and quantified in order to illustrate the variation in results and the need for reliable modelisation and material parameters identification. Mechanical behavioural data is also extracted for the sintered silver simulating a lap shear test, which is used to validate a non-linear identification method of the Anand model parameters. The results show that the inclusion of a diamond die increases significantly the amount of stress and plastic deformation in the die-attach layer, which will lead to reliability problems and shorter life cycle. In addition, when using silver sintering as die-attach, the model parameters should be extracted for each particular material, owing to the fact that the mechanical properties of the die-attach layer strongly depend on its processing conditions. Finally, the Anand model parameter identification routine was validated, obtaining minimum deviation from the original values used to simulate the pseudo-experimental data.