Insulated Gate Bipolar Transistors (IGBTs) are used in applications such as the switching of automobile and train traction motors, high voltage power supplies, and in aerospace applications such as switch mode power supplies (SMPS) to regulate DC voltage. The failure of these switches can reduce the efficiency of the system or lead to system failure. By identifying failure precursor parameters in IGBTs and monitoring them, a prognostics methodology can be developed to predict and avert failures. In this study, IGBTs aged by thermal-electrical stresses were evaluated in comparison with new components to determine the electrical parameters that change with stressing. Three potential precursor parameter candidates, threshold voltage, transconductance, and collector-emitter (ON) voltage, were evaluated by comparing aged and new IGBTs under a temperature range of 25-200oC. The trends in the three electrical parameters with temperature were correlated to device degradation. A methodology is presented for validating these precursor parameters for IGBT prognostics.

Index Terms: Failure precursor parameters, IGBTs, prognostics

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