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A Novel Multi-Physical Coupled Model of Press-Pack IGBT in Steady Conducting State Considering Fretting Wear

The finite element model of press-pack IGBT (PPI) in steady conducting state is significant for its reliability improvement research. The models in the previous literature are not able to realize the fully coupled relationship in the consideration of device aging status and the chip surface roughness. In this paper, a novel multi-physical filed coupled model of PPI considering fretting wear is proposed. This model realizes the coupled of the electrical, thermal and mechanical model through contact resistance. The influence of contact pressure is not necessary to be taken into consideration in the coupled model so that contact resistance only determinates by the surface roughness. Under the utilization of the empirical formula of the contact thermal and electrical resistance in the multi-physical filed coupled model, it is more correct to obtain the junction temperature and pressure distribution under various surface roughness. The observed cracks and the fretting wear phenomenon on the chip surface after power cycling test verify the correctness of the coupled model. The proposed model is meaningful in researching the reliability improvement of PPI.