Prediction of Chip Solder Fatigue in IGBTs

Abstract

Chip solder degradation is one of the main factors affecting the reliable operation of insulated gate bipolar transistor (IGBT) modules. However, there are still many challenges to get the real lifetime of chip solder. This paper proposes a lifetime consumption prediction method based on chip solder failure. First, the constant high junction temperature fluctuations are applied to IGBT modules for the power cycling tests. The transient thermal resistance is measured to monitor the degradation process of IGBT modules for every 1000 times of aging tests. And the failure degree of chip solder is analyzed by the integral structure function. With the help of scanning acoustic microscope, the failure analysis of aging modules is carried out. The finite element simulation model is established to analyze the transient thermomechanical characteristics of chip solder. Then, the influences of different power cycling conditions on the viscoplastic strain of chip solder are analyzed quantitatively. The average value of the viscoplastic strain increment is obtained by the integral method under large thermal loading. Meanwhile, the method is also applicable to the low thermal loading. Finally, a study case of IGBT modules in a 1.5 MW grid‐side wind power converter is given to demonstrate the validity of the proposed method. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.