Sn-Ag-Cu无铅球栅阵列焊点塑性表征

Plastic characterization and performance of Sn-Ag-Cu lead-free BGA solder joint

通过纳米压痕的方法,采用塑性应变与总应变的比值表征塑性,对SAC305/Cu、SAC0307/Cu和SAC0705Bi Ni/Cu这3种无铅焊点的动态硬度、抗蠕变性能及塑性进行了对比。3种焊点的动态硬度随深度变化趋势相同,随着压入深度的增加而降低。SAC0705Bi Ni/Cu的最终动态硬度最高,压痕深度最小,SAC305/Cu表现出应变硬化现象。3种焊点的抗蠕变能力由大到小依次为SAC0705Bi Ni/Cu、SAC305/Cu、SAC0307/Cu。SAC0705Bi Ni/Cu焊点的塑性与SAC305/Cu焊点的相当。与SAC305和SAC0307两种钎料相比,无铅钎料SAC0705Bi Ni通过Bi和Ni元素的加入,提高钎料的硬度和抗蠕变性能,并且保持较好的塑性。

The nanoindentation was performed on the plasticity of Sn-Ag-Cu(SAC) lead-free ball grid array(BGA) solder joint. The ratio of plastic strain to total strain was used to characterize the solder plasticity. SAC305/Cu, SAC0307 /Cu and SAC0705BiNi/Cu component solder joints were compared in terms of dynamic hardness, creep resistance and plasticity. The dynamic hardness of three kinds of solder decreases with increasing the penetration depth. For SAC0705BiNi/Cu, the ultimate dynamic hardness is the highest, and the indentation depth is the smallest. Then, the strain hardening phenomenon of SAC305/Cu is more obvious than that of the others. Thus, the order of creep resistance from big to small is SAC0705BiNi/Cu, SAC305/Cu and SAC0307/Cu. The plasticities of SAC0705BiNi/Cu and SAC305/Cu solder joints are similar. Compared with the other two types of solder, through adding Bi and Ni elements, the hardness and solder creep resistance of SAC0705BiNi solder are improved, and the good plasticity is still maintained.