Tensile properties and microstructural characterization of Sn–0.7Cu–0.4Co bulk solder alloy for electronics applications

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• 作者：Cristina Andersson ; Peng Sun ; Johan Liu
• 关键词：Tensile properties ; Lead-free ; Solder alloy ; Sn&#x2013 ; Cu&#x2013 ; Co ; Strain rate
• 刊名：Journal of Alloys and Compounds
• 出版年：2008
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：12 June 2008
• 卷：457
• 期：1-2
• 页码：97-105
• 文件大小：1928 K

摘要

The ternary Sn–Cu–Co system eutectic composition was obtained by means of CALPHAD (CALculation of PHAse Diagram) methodology and it was found to be 0.4%Co and 0.7%Cu (wt%) with a melting point of 224 °C. The tensile behavior of this alloy was investigated at different strain rates (10⁻⁵, 10⁻⁴ and 10⁻³ s⁻¹) and compared to both Sn–37Pb and Sn–4.0Ag–0.5Cu. The Sn–4.0Ag–0.5Cu alloy depicts the highest ultimate tensile strength (UTS) followed by the Sn–37P and finally the Sn–0.7Cu–0.4Co system. The elastic modulus was also higher for the Sn–4.0Ag–0.5Cu followed by the Sn–0.7Cu–0.4Co and last the Sn–37Pb. The microstructure of the Sn–0.7Cu–0.4Co alloy is composed of two types of intermetallic phases, (Cu,Co)₆Sn₅ and (Co,Cu)Sn₂ dispersed in a Sn-rich matrix. The microstructure of this alloy proved to be very stable, after aging at 150 °C for 24 h. The eutectic Sn–0.7Cu–0.4Co solder alloy can therefore be a very good alternative for the SAC alloys for surface mount technology applications.