Optical in situ analysis of power electronic devices under power cycling conditions
For the visualization and analysis of thermo-mechanical (damage) processes in power electronic devices under active power cycling conditions, an in situ investigation methodology was realized. It is based on an in-plane deformation measurement, for which the structures to be examined are prepared up to the desired grinding level by ensuring at the same time their electrical functionality. In the next step, (microscopic) images are captured under different power cycling loading conditions, both in the loaded and unloaded (initial) state. Based on these images, displacement fields and mechanical strains can be derived by means of digital image correlation. This allows, for example, the analysis of the interaction between chip connections and mold compound for different load scenarios. Furthermore, the approach enables the investigation of thermal transient processes in the cross sectioned device by using an IR camera. However, challenge is the translation of the investigation results back to the unprepared conditions. For this purpose, it is necessary to combine these investigations with FE methods in the future.