3D封装微尺度CSP焊点随机振动应力应变分析

Analysis of stress strain and shape size optimization of 3D micro-scale CSP solder joints in random vibration

基于ANSYS软件建立了3D芯片尺寸封装有限元模型,对模型中微尺度CSP焊点在随机振动载荷条件下进行有限元分析,获得了CSP焊点应力应变分布情况;分析了不同焊点材料、焊盘直径和焊点体积对应力应变的影响;并以焊点体积、焊点高度、焊盘直径为设计参数,以随机振动条件下CSP焊点应力值作为目标值,设计17组试验仿真计算,采用响应曲面法对17组应力值与微尺度CSP焊点形态参数间关系进行拟合,结合遗传算法对拟合函数进行优化.结果表明,随机振动环境下应力值最小的CSP焊点组合参数为焊点最大径向尺寸0.093mm、焊点高度0.077mm、焊盘半径0.068mm,并对最优组合参数仿真验证,最优组合仿真结果优于17组试验仿真结果,实现了随机振动环境下微尺度CSP焊点的结构优化.

Three-dimensional finite analysis models of micro-scale chip-scale package were set up in ANSYS.Microscale chip-scale package (CSP) solder joints were analyzed in the random vibration of loads,then stress and strain distribution of micro-scale CSP were obtained.And the effects of different solder materials,pad diameter,and solder joint volume to stress and strain of micro-scale CSP solder joints were analyzed.The size of the solder joint,solder joint height,the diameter of pad size as design parameters,the value of stress of the micro-scale CSP solder joints as the target value are applied to design and calculation of 17 sets of experiments using computational simulation.The stresses and shape parameters of micro-scale CSP solder joints are fitted by the response surface method and genetic algorithm for fitting function optimization.The results show: the CSP solder joint parameters with the minimum value of stress in the random vibration is,the maximum size of 0.093 mm solder joint,the height of solder joint is 0.077 mm,the radius of the pad is 0.068 mm.Finally,the optimal combination is verified by simulation experiments: the result of optimal combination is better than 17 sets of experimental results,and the optimization of the micro-scale CSP solder joint structure in the random vibration is realized.