摘要
研究了Sn37Pb,Sn3.0Ag0.5Cu和Sn0.7Cu三种焊料BGA焊点在电迁移作用下界面的微观组织结构.在60℃,1×103A/cm2电流密度条件下通电187h后,Sn37Pb焊点阴极界面已经出现了空洞,同时在阳极有Pb的富集带;Sn3.0Ag0.5Cu焊点的阴极界面Cu基体大量溶解,阳极金属间化合物层明显比阴极厚;对于Sn0.7Cu焊料,仅发现阳极金属间化合物层厚度比阴极厚,阴极Cu基体的溶解不如SnAgCu明显,电迁移破坏明显滞后.
The cross-sectional microstructures of joints with Sn37 Pb, Sn3.0 Ag0.5 Cu, and Sn0.7 Cu under electromigration were investigated. At a temperature of 60℃ and current density of 1 × 10^3 A/cm^2 ,after 187h, micro-voids form at the electron entrance of the Sn37 Pb solder/Cu interface, and strip-like Pb enriches the anode side. For Sn3.0 Ag0.5 Cu, electromigration only results in the dissolution of the substrate Cu at the cathode side, and the thicknesses of the Cu6Sn5 and Cu3Sn intermetallic layers at the anode side are markedly bigger than the counterparts at the cathode. Likewise, the Cu6Sn5 and Cu3Sn intermetallic layers at the anode side are thicker than the counterparts at the cathode, indicating that EM also occurs in the Sn0.7CU joint, but little Cu dissolves into the solder at the cathode side.
