Pb/Sn凸剪切性能研究

Study on Shear Strength Characters of Pb/Sn Bump

在实际使用条件下,Pb/Sn凸点会由于承受温度循环而产生剪切应力,剪切应力导致的主要失效方式是开裂.通过对倒装焊后Pb/Sn凸点剪切强度的测量及对剪切后断口的分析,发现破坏主要发生在凸点下金属(UBM)层内部或UBM与Al焊盘之间,平均剪切强度受凸点尺寸影响很小,范围在21～24MPa。

Because of excellent property and low cost, Pb/Sn bump plays a key role in chip level packaging. In practice, its shear strength is induced by temperature recycle and the main failure model is cracking. In this paper, we measured the shear strength of Pb/Sn bumps after bonding and analyzed the fracture positions by SEM. The results of the experiment indicate that most fracture happened in UBM or between UBM and Al pad, and the average shear strength is about 21～24 MPa.