Effect of electroplating layer structure on shear property and microstructure of multilayer electroplated Sn-3.5Ag solder bumps

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• 作者：Qinghua Zhao^a ; ^{zhaoqinghua6708@163.com} ; ^{zhaoqinghua6708@gmail.com} ; Anmin Hu^a ; Ming Li^a ; ^b ; ^{mingli90@sjtu.edu.cn} ; Jiangyan Sun^c
• 刊名：Microelectronics Reliability
• 出版年：2013
• 出版时间：February, 2013
• 年：2013
• 卷：53
• 期：2
• 页码：321-326
• 全文大小：1324 K

文摘

In this paper, Sn-3.5Ag solder bumps were prepared using multilayer electroplating method. The effect of electroplating layer structure (Sn/Ag, Ag/Sn, Ag/Sn/Ag) on shear property and microstructure of solder bumps was investigated.

Shear test revealed that Sn/Ag bumps displayed the highest shear strength among different electroplating layer structures, which was 89.3 % higher than that of pure Sn bumps, and 43.5 % higher than that of Ag/Sn bumps. The interfacial microstructure evolution during reflowing process was also observed. It was found that Cu₆Sn₅ intermetallic compound formed at the interface between solder and Cu and its grain size increased as reflow time increased for all three electroplating structures. When there was Ag electroplated between Sn and Cu (Ag/Sn/Ag and Ag/Sn structures), the morphology of Cu₆Sn₅ was thin, hexagonal and scattered, which could be attributed to the adsorption of Ag₃Sn on the surface of Cu₆Sn₅. In contrast, when Sn was electroplated on Cu directly (Sn/Ag structure), the morphology of Cu₆Sn₅ was thick, rod-like and continuous, which displayed high shear strength.