Prediction of IGBT power module remaining lifetime using the aging state approach

Abstract

Insulated Gate Bipolar Transistor (IGBT) is the core power device in the fields of railways, new energy sources, and automobiles. The safe and reliable operation of IGBT is the basis to ensure the sustained and steady development of all walks of life. The junction-to-case thermal resistance of the IGBT power modules can manifest the fatigue degree of the solder layer. The saturation voltage drop manifests the aging degree of the IGBT bonding wire. Therefore, the IGBT reliability can be judged by a certain rule along with the external parameters such as the junction-to-case thermal resistance Rth and the saturation voltage drop Vce. In order to grasp this rule, this study illustrates the correlations between the external parameters of IGBT and the number of power cycles. As a result, the functional relationships between the average change rate of junction-to-case thermal resistance and the number of power cycles (ΔR¯th—n) as well as the average saturation voltage drop rate of change and the number of power cycles (ΔV¯ce—n) have been gained from IGBT test samples. After obtaining these functional relationships, for any IGBT of the same model in working condition, a proposition of judging the aging degree can be obtained. Here, the aging degree of the IGBT is represented by a real number in the interval [0, 1] and the reliability of the above proposition is calculated from the standard deviation of the working lifetime of each test sample. The method proposed in this study can not only be used to judge the aging degree of IGBT, but also to estimate the remaining lifetime.