BGA器件无铅焊点剪切性能模拟

Simulation on the shear strength for BGA Lead-free solder joint

针对BGA无铅焊点的抗剪切性能问题，基于Anand粘塑性本构方程，利用数值模拟方法研究了试验参数对焊点剪切强度的影响。研究结果表明在不同的剪切速率下，焊点的力学行为是类似的，但是力学响应表现出时间相关性：经过弹性变形阶段、屈服阶段、塑性变形阶段，出现了加工硬化现象，最终在靠近焊球／焊盘界面处断裂失效。在150～350μm／s的剪切速率范围内，随着剪切速率的增加，焊点的剪切力增大了12．6％；当剪切高度在50～200μm范围内变化时，剪切力随着剪切高度的增大降低了2．9％。在高密度细间距焊点的情况下，焊合面积彳较小，此时剪切高度对剪切力大小的影响减弱。研究结果证实了在焊点的剪切试验中存在着“尺寸效应”，焊点的剪切强度与焊球直径成反比例关系。此方法可为焊点剪切试验的参数优化、焊点强度的快速评估等提供参考。

Based on finite element analysis,effects of the shear test parameters on the shear strength of Ball Grid Array(BGA) Lead-free solder joint are investigated,modeled by Anand visco-plastic equations.Both elastic and plastic deformation occurs during the shear test,and yield deformation and work hardening are clearly observed.Fracture grows through the whole solder ball and failure occurs near the interface of the solder joint.In the range of 150-350μm/s,the shear force increased as the shear speed rise by 12.6%.Meanwhile,in the range of 50-200μm for shear height,the shear force is slightly reduced as the height increased.Additionally,the size-effect also exists in the shear test of solder ball and the shear force is inversely proportional to the diameter of solder ball.The study can be applied to the parameter optimization in BGA shear test and also may provide an efficient method to evaluate the reliability of micro BGA solder joint.