Stress distribution of bonding wire of IGBT module under DC power cycling condition

Abstract

The Insulated Gate Bipolar Transistor (IGBT) has been applied in more and more fields because of its advantages of small driving power, low saturation voltage, fast switching speed and strong current processing power. In service, the IGBT module will produce power losses, which leads to the rise of the chip ’ s junction temperature. Temperature and thermal stress have great influence on the reliability of IGBT module. In this paper, the temperature distribution, current density distribution and chip stress distribution of IGBT module under DC power cycling condition were obtained by finite element numerical simulation. The results of electro-thermal analysis show that the main heating area of IGBT module are IGBT chips, the temperature distribution of the module is not uniform. During the power cycling, the current density of the chip changes synchronously with the current load. Thermal-mechanical finite element analysis shows that the maximum stress on the chip surface occurs at the center of the interface between the Al metallization layer and the IGBT chip, and the stress at the corner of the Al metallization layer far from the center is small. The maximum stress value on the Al bonding wire appears at the interface, and the stress in the middle of the bonding wire away from the chip is small. The maximum stress of the interface appears at the corner, and the variation of the stress value in the power cycling is synchronous with the change of the junction temperature of the chip.