Accelerated lifetime testing of power modules is time consuming and expensive due to the destructive nature of these tests. Therefore, it makes sense to extract as much data as possible from each consumed component. Traditional power cycling methods, however, monitor a single parameter and stop the test after this parameter reaches a predefined threshold. This leaves little data available for real-time analysis of the aging process, which instead must take place post-failure. In this paper, we present full results from a power cycling test on SiC MOSFETs which uses a novel method to extract both the semiconductor die resistance and bondwire resistance separately. Using this method, we are able to observe degradation phenomena that has previously been hidden when using conventional monitoring methods. We hope that the presentation of this data will demonstrate the incentive to incorporate smart monitoring functions during accelerated lifetime testing of power semiconductors. In essence, we aspire to advance the techniques in this area to provide a ‘window’ into the module, which allows the failure process to be accurately observed in real time. In turn, we hope these methods will allow more targeted improvements to module design from a reliability perspective.
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