Fatigue failure of insulated gate bipolar transistor modules (IGBTs) packages under low-amplitude temperature swings is of great significance for the reliability evaluation of IGBTs operating in actual power electronic devices. In this article, failure mechanism of die-attach joints in IGBTs under normal operating and accelerated aging was comparably investigated by a three-dimensional electro-thermal-mechanical coupled model. Results indicated that local viscoplastic deformation of solder alloys around stress concentrated areas caused by material microdefects is the root cause of fatigue of die-attach joints under low-amplitude temperature swings. Fatigue cracks can only initiate and propagate at those plastically deformed areas (activation points). Fatigue of die-attach joints is co-determined by the number of activation points and crack growth rate. Comparably, the whole die-attach solder is in viscoplastic deformation under accelerated aging and the number of activation points has reached its saturation. Fatigue of die-attach joints under accelerated aging is only determined by the crack growth rate. Due to the difference in failure mechanism, it is questionable to directly extend conventional life models to normal operating conditions. Accordingly, an energy-based physical life model for die-attach joints in IGBTs under low-amplitude temperature swings was proposed.

中文翻译：

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基于 3D 电热机械有限元模拟的低幅度温度摆幅下 IGBT 芯片连接点的疲劳机制

绝缘栅双极晶体管模块（IGBTs）封装在低幅度温度摆幅下的疲劳失效对于IGBTs在实际电力电子器件中运行的可靠性评估具有重要意义。本文通过三维电-热-机械耦合模型，对比研究了IGBT在正常工作和加速老化条件下贴片接头的失效机理。结果表明，材料微缺陷引起的应力集中区域周围焊料合金的局部粘塑性变形是低幅度温度波动下贴片接头疲劳的根本原因。疲劳裂纹只能在那些塑性变形区域（激活点）处产生和扩展。芯片连接点的疲劳由激活点的数量和裂纹扩展速率共同决定。相比之下，整个贴片焊料在加速老化下处于粘塑性变形，激活点的数量已达到饱和。加速时效下芯片连接的疲劳仅由裂纹扩展速率决定。由于故障机制的不同，将常规寿命模型直接扩展到正常运行条件是值得怀疑的。因此，提出了一种基于能量的低幅度温度波动下 IGBT 芯片连接点的物理寿命模型。加速时效下芯片连接的疲劳仅由裂纹扩展速率决定。由于失效机制的不同，将常规寿命模型直接扩展到正常运行条件是值得怀疑的。因此，提出了一种基于能量的低幅度温度波动下 IGBT 芯片连接点的物理寿命模型。加速时效下芯片连接的疲劳仅由裂纹扩展速率决定。由于失效机制的不同，将常规寿命模型直接扩展到正常运行条件是值得怀疑的。因此，提出了一种基于能量的低幅度温度波动下 IGBT 芯片连接点的物理寿命模型。