IGBT薄层电极脱落机理分析与寿命预测方法  

Analysis on the Lift-off of IGBT Thin Electrode and Prediction Method of the Life

作　　者：李磊 麻长胜 王晓宝[1] 赵善麒[1] LI Lei;MA Chang-sheng;WANG Xiao-bao;ZHAO Shan-qi(MA CMIC Science and Technology Corporation,Changzhou 213000,China)

机构地区：[1]江苏宏微科技股份有限公司,江苏常州213000

出　　处：《电力电子技术》2020年第3期127-129,共3页Power Electronics

基　　金：江苏省科技专项基金(BA2016091)。

摘　　要：芯片表面电极薄层脱落是绝缘栅双极型晶体管(IGBT)封装模块的一种常见失效现象,因此对其失效机理分析与寿命的有效预测是整体器件可靠性评估中的一个研究要点。首先通过仿真分析了芯片表面电极的应力应变随功率循环载荷的变化情况,发现芯片表面铝电极薄层与引线的键合位置附近区域存在应力集中情况,且应力集中的位置与实验中失效样品的断裂位置一致。此外还发现应力集中区仅在起初的短时间内存在一个逐渐减小的塑性应变幅,随后由于材料硬化,塑性屈服点上移,直至失效塑性应变都不再变化,因此可以推测材料的断裂失效是由于稳定后的塑性应变和循环应力综合导致的,鉴于上述分析,提出了一种同时考虑材料硬化和应力疲劳的寿命预测公式,并采用其他两种条件下的实验寿命值评估了此公式的准确性,总体平均误差为1%。Lift-off of the thin chip electrode is a common problem of insulated gate bipolar transistor(IGBT)modules,therefore,analysis on the failure mode and effective life prediction is a vital ingredient of the reliability assessment of IGBT modules.The stress and strain of a thin chip electrode changing with a periodic power load are studied by simulation method,and the result shows that there are some areas of concentrated stress in the thin chip electrode near the bonding joint which is consist with the experimental result.In addition,the decreasing plastic strain amplitude of the stress concentration areas only exists in a short time at first,and then due to the rise of the yield strength of the hardened material,the plastic strain stops changing and keeps on a steady value.Therefore,the lift-off of the electrode is formed by steady plastic strain and stress fatigue of the aluminum material together.Based on the analysis above,a prediction equation considering both material hardening and stress fatigue is proposed.Finally,the accuracy of the prediction equation is also studied by using the other two groups of experimental life values and the average error is 1%.

关 键 词：绝缘栅双极型晶体管 薄层电极 寿命预测 

分 类 号：TN32[电子电信—物理电子学]