수치해석을 이용한 전동차용 IGBT 모듈의 피로 수명 예측

In this study, the thermomechanical stress and fatigue analysis of a high voltage and high current (3,300 V/ 1200 A) insulated gate bipolar transistor (IGBT) module used for electric locomotive applications were performed under thermal cycling condition. Especially, the reliability of the copper wire and the ribbon wire were compared with that of the conventional aluminum wire. The copper wire showed three times higher stress than the aluminum wire. The ribbon type wire showed a higher stress than the circular type wire, and the copper ribbon wire showed the highest stress. The fatigue analysis results of the chip solder connecting the chip and the direct bond copper (DBC) indicated that the crack of the solder mainly occurred at the outer edge of the solder. In case of the circular wire, cracking of the solder occurred at 35,000 thermal cycles, and the crack area in the copper wire was larger than that of the aluminum wire. On the other hand, when the ribbon wire was used, the crack area was smaller than that of the circular wire. In case of the solder existing between DBC and base plate, the crack growth rate was similar regardless of the material and shape of the wire. However, cracking occurred earlier than chip solder, and more than half of the solder was failed at 40,000 cycles. Therefore, it is expected that the reliability of the solder between DBC and base plate would be worse than the chip solder.