计及内部材料疲劳的压接型IGBT器件 可靠性建模与分析

大功率压接型IGBT器件更适合柔性直流输电装备应用工况，必然对压接型绝缘栅极晶体管（IGBT）器件可靠性评估提出要求。提出计及内部材料疲劳的压接型IGBT器件可靠性建模方法，首先，建立单芯片压接型IGBT器件电-热-机械多物理场仿真模型，通过实验验证IGBT仿真模型的有效性；其次，考虑器件内部各层材料的疲劳寿命，建立单芯片压接型IGBT器件可靠性模型，分析了单芯片器件各层材料薄弱点；最后针对多芯片压接型IGBT器件实际结构，建立多芯片压接型IGBT器件多物理场仿真模型，分析器件应力分布，并对各芯片及多芯片器件故障率进行计算。结果表明，压接型IGBT器件内部的温度、von Mises 应力分布不均，最大值分别位于IGBT芯片和发射极钼层接触的轮廓线边缘；多芯片器件内应力分布不均会导致各芯片可靠性有所差异，边角位置处芯片表面应力最大，可靠性最低。

Reliability Modeling and Analysis of Press-Pack IGBTs Considering Internal Material Fatigue

The high power press-pack IGBTs (Insulated Gate Bipolar Transistor) devices are more suitable for flexible HVDC high power system. It is inevitable to meet the requirements for reliability evaluation of press-pack IGBTs. In this paper, a reliability modeling of press-pack IGBTs considering material fatigue is proposed. Firstly, the electro-thermal-mechanical multi-physics simulation model of single-chip press-pack IGBT device is established and the effectiveness of the IGBT simulation model is verified by experiments. Secondly, the reliability model of single-chip press-pack IGBT device is established considering the fatigue life of materials and the weak points of each layer of single-chip device are analyzed. Finally, the multi-physics simulation model of multi-chip press-pack IGBTs is established based on the actual structure. The stress distribution of the devices is analyzed, and the failure rates of each chip and multi-chip devices are calculated. The results show that the temperature and von Mises stress distribution inside the press-pack IGBTs are uneven. The maximum values are located at the edge of the contour of the contact between the IGBT chip and the emitter molybdenum layer. The chip current, temperature and thermal-mechanical stress distribution are uneven in the multi-chip device. The reliability level of the internal chip is obviously different because of uneven stress distribution in multi-chip devices. The chip at the corner of the device bears the maximum stress and the reliability is the lowest.