降温速率对SnPb焊点微观组织及力学性能的影响

摘要

以BGA植球模拟回流焊焊点形成过程,控制冷却方式以调节植球过程中的降温速率,进而研究降温速率对SnPb共晶焊点微观结构及力学性能的影响.试验结果表明,降温速率对共晶焊点微观组织结构和力学性能均具有较大影响.随着降温速率由0.45℃/s增加至1.05℃/s,焊点内部靠近焊盘侧以枝晶形态存在的富铅相尺寸减小,且远离焊盘侧焊球内部相偏析程度降低,相应的焊球与本体焊盘之间结合强度由7.52 N增加到9.02 N.%Formation of solder joint during reflow process was simulated using attachment of solder balls for BGA device. The cooling rates, which could influence the microstructures and mechanical properties of eutectic SnPb solder joints conspicuously, were adjusted by controlling the cooling mode of the equipment. The dimensions of the Pb-rich dendritic phase nearby the BGA body pads decreased with the cooling rate changing from 0.45℃/s to 1.05℃/s. Moreover, the phase segregation weakened away from the body pads and the shear strength between the solder balls and the pads increased from 7.52 N to 9.02 N.