In-situ Detection of Degradation in Power Electronic Modules During Lifetime Testing using Lock-in Thermography

Within the scope of this work lock-in thermography is applied for the detection of the development of degradations during the lifetime testing of power electronic modules. For this purpose, the measurement technique has been implemen ted in a test bench for active power cycling of power electronic modules. This avoids interrupting the test for the data acquisition phase and the lifetime tests can be executed as usual. Metallographic cross-sections, scanning acoustic microscopy (SAM) and X-ray micro tomography were carried out for the verification of the failure mechanism. From the observations it is concluded that lock-in thermography is suitable for in-situ non-destructive detection of crack propagation in the metallisation of in power electronic semiconductors. Furthermore, the presented method is also suited for illustration of the development of the failure mechanism. Therefore it is a valuable tool to obtain an understanding of the examined failure mechanisms.