Improving the impact toughness of Sn-Ag-Cu/Cu-Zn Pb-free solder joints under high speed shear testing

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• 作者：Chi-Yang Yu ; Wei-Yu Chen ; Jenq-Gong Duh
• 关键词：Intermetallics ; Metals and alloys ; Surfaces and interfaces ; Mechanical properties ; Microstructure
• 刊名：Journal of Alloys and Compounds
• 出版年：15 February, 2014
• 年：2014
• 卷：586
• 期：Complete
• 页码：633-638
• 全文大小：2364 K

文摘

This study aims to investigate the interfacial reaction and the impact reliability of Sn-3.0Ag-0.5Cu/Cu-15Zn (wt.%; SAC/Cu-Zn) solder joints. The Cu-Zn under bump metallization (UBM) was developed to replace the traditional Cu UBM in the Pb-free solder joints. In the Sn-Ag-Cu/Cu solder joint, thick Cu₆Sn₅ and Cu₃Sn intermetallic compounds (IMCs) formed at the interface after thermal aging at 150 掳C for 1000 h. In contrast, the SAC/Cu-Zn solder joint shows a thinner Cu₆(Sn,Zn)₅ layer, and the growth of Cu₃Sn IMC was absolutely suppressed at the SAC/Cu-Zn interface. To evaluate the bonding energy, the high speed shear testing was carried out to correlate the microstructure of solder joints. It is noteworthy that the SAC/Cu-Zn solder joint can enhance the impact toughness. The higher impact toughness of SAC/Cu-Zn is attributed to the thinner and tougher Cu₆(Sn,Zn)₅ IMC at the joint interface. Accordingly, Cu-Zn alloy is a potential UBM material for Pb-free solder joints to improve the impact reliability.