压接型IGBT器件接触电阻计算及影响因素分析

Calculation and Analysis of Influence Factors of Electrical Contact Resistances Inside Press-pack IGBT Device

压接型IGBT器件封装材料间的接触电阻大小及分布规律直接影响其电热分布特性与运行可靠性,然而现有接触电阻计算的方法大都依赖于半经验模型,未能考虑表面形貌参数影响,难以准确表征,该文提出考虑材料表面形貌参数及接触压力影响的压接型IGBT器件接触电阻模型及影响规律研究。首先,基于电接触理论,建立考虑材料电阻率、接触面接触压力、粗糙度及微硬度参数的接触电阻数学模型。其次,通过分析材料表面特性选定接触电阻模型参数,建立单芯片压接型IGBT器件有限元仿真模型计算接触压力,获取器件内部接触电阻分布规律,并通过器件导通电阻测量,间接验证所建接触电阻模型的有效性。最后,分析接触压力、芯片电阻率及表面粗糙度对压接型IGBT器件接触电阻的影响规律。结果表明,相对COMSOL软件内置模型,所建接触电阻模型可更加准确地表征器件内部接触电阻变化规律。相比其他接触面,芯片与钼片间的接触电阻最大,且当接触压力较小时,接触电阻受电阻率、粗糙度及压力的影响更明显。

Electrical contact resistances of the press-pack insulated gate bipolar transistor(IGBT)device directly affect electro-thermal distribution characteristics and operational reliability of the device.However,the existing contact resistance calculation methods rely on the semi-empirical model or the built-in model of the finite element software and fail to consider the influence of surface topography parameters.The electrical contact resistances cannot be calculated accurately.An electrical contact resistance model and influence laws of the press-pack IGBT device considering the influence of material surface morphology parameters and contact pressure were proposed.Firstly,a mathematical model of electrical contact resistance that takes into account material resistivity,contact pressure,roughness and microhardness parameters was established based on the electrical contact theory.Secondly,the parameters of the electrical contact resistance model were selected by analyzing the surface characteristics of the material.A finite element simulation model of a single-chip press-pack IGBT device was established.The contact pressure and electrical contact resistances of the device were calculated.The validity of the proposed model was indirectly verified by measuring the on-resistance of the device.Finally,the effects of contact pressure,chip resistivity and surface roughness on the electrical contact resistances were analyzed.The results show that the proposed electrical contact resistance model can accurately characterize the electrical contact resistances of the device compared with the built-in model of COMSOL software.The electrical contact resistances between the chip and the upper and lower molybdenum in the press-pack IGBT device are the largest.When the pressure is small,the electrical contact resistances change significantly due to the resistivity,roughness and pressure.