Nanoindentation study on micromechanical behaviors of Au-Ni-Sn intermetallic layers in Au-20Sn/Ni solder joints

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• 作者：Wensheng Liu ; Yikai Wang ; Yunzhu Ma ; ^{zhuzipm@csu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Qiang Yu ; Yufeng Huang
• 关键词：Micromechanical properties ; Nanoindentation ; Au&ndash ; 20Sn ; Intermetallics
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：20 January 2016
• 年：2016
• 卷：653
• 期：Complete
• 页码：13-22
• 全文大小：4367 K

文摘

Micromechanical behavior of interfacial intermetallics is closely related to the reliability of micro solder joints. Nanoindentation was employed to investigate the micromechanical behavior of the (Au,Ni)Sn and (Ni,Au)3Sn2 intermetallic layers in Au–20Sn/Ni solder joints. The indentation size effect (ISE) of both intermetallics was quantitatively analyzed. Based on the ISE parameters, the average Burger's vectors of (Au,Ni)Sn and (Ni,Au)3Sn2 were determined to be 2.38×10⁻¹⁰ nm and 4.09×10⁻¹⁰ nm, respectively. The first pop-in event is associated with the elastic–plastic deformation transition and shows an obvious rate-dependent: both the first pop-in load and the maximum shear stress increased with the loading rate. The apparent activation volumes of pop-in were calculated to be 0.11b³ and 0.02b³ for (Au,Ni)Sn and (Ni,Au)3Sn2, respectively. The apparent activation volume determined from the stress relaxation increased with the loading rate because of the preferential activation of preexisting dislocations and the longer average distance that dislocations have to travel under high loading rate. From nanoindentation creep tests, the average stress exponent of (Au,Ni)Sn and (Ni,Au)3Sn2 were determined to be 0.86 and 1.42, respectively.