摘要
纳米银的热膨胀系数与模块中其他组件存在较大差异,导致在严苛环境下工作时发生热疲劳失效.因此,预测纳米银烧结层的热疲劳寿命成为关键问题.以SiC功率模块为对象,利用有限元仿真和修正的Coffin-Manson寿命预测模型,分析了纳米银烧结层在热循环载荷下的最大等效应力和疲劳寿命.进一步通过响应面法分析,以疲劳寿命为优化目标,选取了 SiC芯片和纳米银烧结层最佳参数组合,并探究铜基板镀镍对疲劳寿命的影响.研究结果显示:在累积的热循环下,纳米银烧结层边角处的等效应力最大,最容易发生热疲劳失效.通过优化设计,当SiC芯片厚度取0.15 mm,纳米银烧结层厚度取0.1 mm时,最大等效应力降低了 1.36％,疲劳寿命增加了 1.57倍.此外,铜基板上的镍层与纳米银烧结层具有相适应的材料属性,能够降低纳米银烧结层的等效应力,并增加其疲劳寿命.
Abstract
The coefficient of thermal expansion of nano-silver differs significantly from that of other components in the module,leading to thermal fatigue failure in harsh environments.Therefore,it is a critical to predict the thermal fatigue life of nano-silver sintering layer.For SiC power module,finite element analysis and the modified Coffin-Manson life prediction model were used to analyze the maximum equivalent stress and fatigue life of nano-silver sintering layer under thermal cycling loading.Through response surface method analysis,the optimal combination between SiC chip and nano-silver sintering layer was determined with fatigue life as the optimization objective,and the effect of nickel plating on fatigue life of copper substrate was explored as well.The research results indicate that under accumulated thermal cycles the maximum equivalent stress occurs at the corner of the nano-silver sintering layer,making it more susceptible to thermal fatigue failure.The optimized thickness of SiC chip and nanosilver sintering layer are 0.15 mm and 0.1 mm,respectively,which reduce the maximum equivalent stress by 1.36％and increase the fatigue life by 1.57 times.Additionally,the nickel layer on the substrate is compatible with the nano-silver sintering layer,which can reduce the equivalent stress of the nano-silver sintering layer and increase its fatigue life.
基金项目
广西壮族自治区创新驱动重大专项(桂科AA21077015)
维普
万方数据