Thermo mechanical Fatigue of Connections in Semiconductor Power Modules

Partners : LMGC (UM)

Researchers : G. Pellecuer (PHD student), F. Forest (Professor), J-J. Huselstein (Assistant professor), A. Chrysochoos (Professor – LMGC UM)

Duration : 3 years (2016-2019)

The subject is the aging of power semiconductor modules. In operation, these modules undergo a clean heating, which can vary cyclically over time when the application imposes a variable electrical regime. This is called thermal cycling, a mechanism that imposes significant thermo mechanical stresses on the internal connections and can lead to their damage. This problem is the heart of the thesis work. It relies on the integration of adapted constitutive laws in software tools of the "finite element" type to lead the study of a module representative of the current technology. From an experimental point of view, the implementation of tests on "classical" modules is relatively complex and the exploitation of results by imaging techniques requires significant prior work. To overcome these drawbacks, the work presented here proposes a procedure for making specific samples focusing on the aging of a bonding wire. The use of these new test vehicles makes it easier to follow the damage and facilitates post-aging analysis. In addition, aging studies on generic modules for different values ​​of cycling speeds make it possible to evaluate the hypothesis of the independence of fatigue with respect to this cycling speed.