Lifetime Prediction Method for IGBT Modules Under Combined Power Cycling–Vibration Conditions

Certain insulated gate bipolar transistor (IGBT) modules, such as automotive-grade IGBT modules, are often subjected to harsh service environments. Generally, two factors, temperature variation and vibration, exist simultaneously. Under the combined effects of thermal stress and dynamic mechanical stress, the process of crack extension in Al bonding wires accelerates, leading to the premature failure of IGBT modules. However, little is known about the lifetime prediction method that can be used for IGBT modules under combined power cycling–vibration loading conditions. First, this paper establishes a lifetime prediction method that is applicable for predicting the lifetime of IGBT modules under power cycling conditions; this method includes a power loss model, an RC thermal network model and a collector–emitter on-resistance $(r_{\mathrm { ce}})$ degradation model. Then, the effect of vibration on the lifetime of the IGBT module is considered in the lifetime prediction method by equating the vibration stress with the thermal stress via finite element (FE) analysis. The method considers the service conditions under combined power cycling–vibration conditions and the self-acceleration effect of Al bond wire damage accumulation on the lifetime of IGBT modules. Using comparisons with experimental results, it is verified that the lifetime prediction method can accurately and efficiently predict the life of an IGBT module under both power cycling conditions and combined power cycling–vibration conditions.