计及内部材料疲劳的压接型IGBT器件可靠性建模与分析

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

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。

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 multichip 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.