Abstract
The thesis topic is the aging of semiconductor power modules. During operation, these modules undergo a specific heating which can vary cyclically over time when the application requires a variable electric mode. This is referred to as thermal cycling, a mechanism that imposes significant thermomechanical stresses developed by the internal connections and can lead to their damage. This problem constitutes the core of the thesis work. It will rely on the integration of adapted constitutive behavioural laws into "finite element" software tools to study a module representative of current technology. From an experimental standpoint, the implementation of tests on "classical" modules is relatively complex and the exploitation of the results by imaging techniques requires significant preliminary work. To overcome these drawbacks, the work presented here proposes a specific sample production approach focusing on the ageing of a bonding wire. The use of these new test vehicles makes the monitor damage easier as well as post-ageing analysis. In addition, ageing studies on generic modules for different cycling frequencies should help us to better understand the hypothesis of the independence of fatigue with respect to cycling speed.