パワーモジュール用Alワイヤ接合部の遷移クリープ熱疲労評価における破壊パラメータの検討

抄録

A power module is a key product for energy saving, and an important part of it is the junction between wires and semiconductor chips. At this joint, damage occurs due to repeated thermal loads due to shortperiod operation of power devices. One of the Al-Si junction damages due to thermal fatigue is the wire-liftoff phenomenon in which the Al wire separates from the Si chip. It is known that the thermal fatigue life of Al tends to saturate at high temperatures above 200°C due to the wire-liftoff phenomenon. To clarify this phenomenon exactly, it is necessary to perform a thermo-elastic-plastic creep analysis. One of the purposes of this study is to confirm the relationship between the fracture parameter and the thermal load cycle pattern that can analytically reproduce this saturation tendency. Thermo-elastic-plastic creep analysis was carried out by modeling the delamination phenomenon. As a result, it was found that the initial temperature at the start of the thermal load cycle has a large effect on the temperature characteristics of the fracture parameters.