Etude de la fatigue thermo-mécanique de modules électroniques de puissance en ambiance de températures élevées pour des applications de traction de véhicules électriques et hybrides

The work presented in this thesis focused on the study of thermo-mechanical fatigue of IGBT power modules inverters integrated 600V-200A for electric and hybrid traction applications. We sought to evaluate the holding of these modules to thermal cycling constraints (power and thermal) under high ambient temperatures. Thus, the first part of this thesis presents the experimental tests conducted under power cycling during which we sought to assess the reliability of IGBT modules (600V-200A) operating at different ambient temperatures (case temperatures) and different temperatures junction (chips temperature). To try to understand the physical mechanisms involved in the degradation of the assembly, testing were stopped when a failure criterion indicate a possible initiation of degradation processes. In the second part, we focused on the reliability of substrate/case solders under the same conditions of thermal cycles. Given the usual acceleration factor chosen for the ageing of these solders is the amplitude of thermal cycles, we sought in this part to evaluate not only the effect of the amplitude of thermal cycles but also the effects of levels of the high and low dwells on the initiation of cracks in these solders and their propagation rate during the cycling. Finally, to understand and analyze the behavior of soldering and assembly under thermal constraints, we perform numerical simulation which is presented in the last part. We applied the same temperatures conditions as those imposed in the experimental part and then locate and evaluate the constraints undergone by the assembly. Above all, we give some answers to establish a link between the parameters of thermal cycling liabilities and the physical quantities that are affecting the lifetime of solders. Finally, we present a numerical study in which we sought to simulate the combined effect of power and thermal conditions on thermo-mechanical constraints in IGBT modules to reflect the constraints imposed in a real application.