内部压力不均对压接式IGBT器件电热特性的影响分析

Simulation of Influence of Unbalanced Clamping Force on Electro-Thermal Characteristics of Press-Pack IGBT Devices

大规模多芯内部并联的压接式IGBT(PPI)器件是柔性直流输电装备的关键部件,针对器件设计和工艺等因素可能导致并联芯片内部压力不均、压接式封装结构难以直接提取内部压力不均状况及其影响的问题,提出一种基于单芯压接式器件并联,模拟研究多芯器件内部压力不均影响的方法。首先,基于压力对单芯器件的影响规律,建立两个独立PPI器件并联的有限元模型,模拟分析不同压力对多芯并联器件电热特性的影响。然后,建立两个单芯PPI器件并联运行的模拟实验平台,验证并联仿真模型的有效性。最后,将并联模型拓展至3300V/1500A实际PPI模块的特性仿真,分析了多芯并联模组内部压力不均对电热特性的影响规律。结果表明,内部压力不均影响多芯并联器件内部的电、热特性分布,其中压力对热阻的影响是器件温度分布的决定性因素,而且随着压力不均程度的增加,芯片间的电热特性差异更明显。压力不均导致的温度差异随着老化程度的增加而增加,并将进一步加速芯片老化,严重影响器件的可靠性。

Press-pack IGBT(PPI)devices,which have large-scale parallel multi-chip,are the key components of flexible DC transmission equipment.Due to the design and manufacture of the PPI devices,the internal clamping force on the parallel chips may be unbalanced,while the unbalanced internal clamping force cannot be tested directly.In this paper,a method to simulate the influence of the unbalanced internal clamping force on multi-chip module by a parallel finite element model of single-chip devices is proposed.Firstly,based on the effect of pressure on single-chip devices,a parallel finite element model of PPI is established.The distribution of the electro-thermal characteristics in parallel multi-chip devices under different internal clamping force is then simulated.Secondly,a test experiment platform with two single PPI devices running in parallel was established to verify the parallel simulation model.Finally,the parallel model was used in the simulation of the actual PPI module of 3 300V/1 500A,and the influence of the unbalanced clamping force of the multi-chip parallel module on the electro-thermal characteristics was analyzed.The results show that the unbalanced clamping force affects the electrical and thermal characteristics of the multi-chip parallel device.The thermal resistance changing with the clamping force is a significant factor in the temperature distribution of the parallel device.With the increase of the pressure inhomogeneity,the difference in electro-thermal characteristics among the parallel multi-chips becomes more obvious.Furthermore,the temperature difference caused by the unbalanced clamping force increases with the aging of the device,which affects the reliability of the device seriously.