基于电热模型的IGBT结温预测与失效分析

摘要

Aiming at the difficulty of measuring junction temperature of insulated gate bipolar transistor (IGBT) in work, a method of forecasting junction temperature based on electro-thermal model was present. Moreover, failure caused by over-high junction temperature was analyzed experimentally. Based on the characteristic of IGBT structure, on-state voltage drop modei was set up. And considering the relationship between the internal parameters and semiconductor physical constant and temperature, the electro-thermal model of power dissipation related to junction temperature was also established. The application of the junction-case conduct equation and the power dissipation model has led to the solutions to the steady junction temperature. The experiment results show that the simulated junction temperature is accordant to actual measured value, and over-high junction temperature could lead to pole root solder melt and bonding wire of surface joint breakdown. Therefore, this method of forecasting junction temperature by inspecting case temperature has merit of convenience and rapidness.%针对绝缘栅双极型晶体管(IGBT)工作过程中结温难以测量的问题,提出一种基于IGBT电热模型的结温预测方法,并对由结温过高引起的失效进行实验分析.根据IGBT结构特点建立通态压降模型,考虑到器件内部参数和半导体物理常数与温度的关系,建立IGBT导通功耗与结温关系的电热模型.通过联立IGBT结-壳传热方程和电热模型进行热平衡分析,从而得到稳态时的结温.实验结果表明,通过仿真得到的结温基本与实际测量得到的结温值相吻合,结温过大会导致电极根部焊料熔化和表面连接键丝断裂.所提方法通过监测壳温可实时预测IGBT结温,具有方便快捷的优点.