电场作用下CSP的失效行为

Failure behavior of CSP induced byelectrical field

主要研究95.5Sn3.8Ag0.7Cu焊球电迁移过程和焊点的失效行为,发现焊点的电迁移过程主要分为3个阶段:微孔洞的孕育与形成、孔洞的聚集和快速失效阶段。Cu6Sn5生长速率随着环境温度的升高而增大,Cu3Sn在UBM和Cu6Sn5的界面处也随着Cu6Sn5的长大而生成并生长,PCB侧的Cu焊盘在电子风的作用下溶解。焊点的失效模式主要为焊盘的溶解、焊球两个界面的裂纹生长断裂和焊球的熔化。

The electromigration process and failure behaviors of 95.5 Sn3.8 Ag0.7 Cu solder bumps were in-vestigated. And it was found that the electromigration of bumps had three main stages：the incubation and formation of micro-hole,the assemblyof holesand therapid failure. Cu6 Sn5 grew faster with the elevated tem-perature. Cu3 Sn generated and grew at the interface between UBM and Cu6 Sn5 as Cu6 Sn5 grew. The copper pad dissolved under the electron wind at PCB side. The three failure models of solder bump were identified as the copper pad dissolution,the crack propagation at two sides of solder bumps’interface and the meltingof solder.