Research about Thermal Fatigue Characteristic of IGBT Module in Considering of Electro-Thermal-Mechanism Coupling and Crack

焊料层缺陷是引起功率器件失效的主要诱因之一，分析不同焊料层缺陷作用下功率器件的热力特性是提高功率器件可靠性的有效手段。本文首先建立了IGBT模块热-力特性分析的电-热-力多物理场全尺寸模型，该模型基于测量参数考虑了材料温度依赖性和力学特性；其次，分析了焊料层空洞和焊料层脱落分层在功率循环以及小载荷下对模块热力特性的影响规律。结果表明所建立的电-热-力多物理场模型能够较好表征焊料层空洞和焊料层脱落时功率器件热力特性的影响规律。当焊料层中出现空洞后，芯片表面温度分布发生了明显改变，高温主要集中在空洞边缘区域；当焊料层疲劳累积到一定程度后将进入非线性扩展阶段，模块热阻和结温呈指数函数增大，直至失效。 Solder defect is one of the main causes of failure in power module, and the thermal stress analysis is an effective way to improve its reliability. In the paper, an electro-thermal-mechanical coupling model is built, which considers the temperature dependent of material and mechanical characte-ristic based on measurement parameters, and the built model is verified by experimental results. In addition, the influence of solder crack on the damage accumulation, as well as the fatigue damage under power cycling and small thermal loading cases is investigated. Finally, the condition as-sessment model is proposed in considering of the effect of crack damage. Results show that the built model can well characterize the influence of the solder layer void and the solder layer shedding on the thermal characteristics of the device. When the voids in the solder appear, the temperature distribution of the chip changes obviously, and the high temperature is mainly concentrated in the hollow edge region. When the fatigue layer of the solder accumulates to a certain extent, it will enter the nonlinear expansion stage. The module thermal resistance and junction temperature exponentially increase until failure.