Approach of a physically based lifetime model for solder layers in power modules

• A physic-based approach for life-time estimation in power cycling tests is presented.
• The presented approach is supported by numerical simulations.
• The simulation data is updated in each crack propagation step.

For the calculation of the lifetime of power modules only empirical lifetime models are available. These models represent a best-fit of a large number of results from power cycling tests, and are not derived from a physical model. In this paper a physic-based approach will be presented. Crack propagation in a solder layer, the increase of the thermal resistance and therewith the expected lifetime is calculated.