An Improved Stress-strain Model Considering the Aging Effect of Solder Layers

Insulated gate bipolar transistor (IGBT) modules are widely used in the power electronic system. It is necessary to monitor the aging process of power modules and do further lifetime prediction to ensure the safety and reliability of the system. In this paper, an improved stress-strain model used by Clech algorithm is proposed, which considers the aging effect of solder layer. In the improved model, correlation terms that characterize the aging of solder layers are added and solved by using the finite element analysis. Then the stress-strain relationship in any aging stage can be obtained more quickly by the improved stress-strain model, instead of re-simulating after changing the model parameters, which greatly reduces the cost of time. The proposed improvement can provide a powerful tool for accurate lifetime prediction.