Long Term Transformation Of Cu / Sn Intermetallic Compounds in Large Solder Joints

Overview & Synopsis

Good thermal performance and thermomechanical stability is required for baseplate solder layers in power modules. Intermetallic compounds, which are formed during the solder process, ensure a strong interconnection. Diffusion, induced by high temperature, in solid state of certain elements into structures of other elements can result in the formation of voids or changes in the mechanical properties. In this work the effect of long term high temperature storage on the baseplate solder layer is evaluated using non-destructive and destructive methods. Parameters for accelerated testing were identified within this study. Variations of temperatures, storage durations and materials were investigated. Furthermore, the influence of structural change to thermal resistance is examined by comparing different species of aged and damaged structures.