板级跌落冲击载荷下无铅焊点形状对BGA封装可靠性的影响

焊点高度和焊盘尺寸相同情况下，分析焊点形状（桶形、柱形、沙漏形）对BGA封装在板级跌落冲击载荷下可靠性的影响。根据不同焊点形状建立3种3D有限元模型，采用Input-G方法将加速度曲线作为数值模型的载荷输入，对BGA封装件在板级跌落冲击载荷下的可靠性进行分析。结果表明：在跌落冲击过程中，在0.1ms左右PCB板出现最大弯曲变形；焊点形状对BGA封装件在跌落冲击过程中的可靠性有较大的影响；以最大剥离应力作为失效准则对三种焊点进行寿命预测, 沙漏形焊点的平均碰撞寿命值最大，其次是柱形焊点，桶形焊点最小，表明沙漏形焊点在跌落测试中表现出较好的抗跌落碰撞性能。

Effects of solder joint shapes on reliability of BGA packages under board level drop impact loads

Under Board Level Drop Test，the effects of solder joint shape (barrel, cylinder, hourglass) on Reliability of BGA Packages were analyzed for the same joint height and the same copper pad size. According different solder joint shape, three of 3D finite element model of BGA packages were created. With conducting reliable analysis of BGA packaging in board-level drop condition, impact acceleration curve is applied to numerical simulation in Input-G method. The results showed that：The maximum bending deformation of PCB board arrived at about 0.1ms during the process of drop test; The solder joint shape has greater effect on reliability of BGA packages under board level drop test; The lifetime of three kinds of solder joint were predicted based on the maximum peeling stress, and it showed that the hourglass solder joint had maximum fatigue life, the next was cylinder solder joint and the least was barrel solder joint, therefore, the hourglass solder joint had excellent properties resistance against drop impact.