Effect of Cu&lt;inf&gt;6&lt;/inf&gt;Sn&lt;inf&gt;5&lt;/inf&gt; particles on microstructure formation and mechanical properties of Sn-58Bi solder

Xiaoying Liu,Ning Zhao,Mingliang Huang

doi:10.1109/icept-hdp.2012.6474649

Abstract

With the development of surface mount technology, solders are required for applications that require high reliability and dimensional stability. Composite solders, reinforced with particles in a conventional solder alloy, is an attractive and potential method. This study presents series results on the binary eutectic Sn-Bi composite solders reinforced with Cu 6 Sn 5 particles (0.5wt.% and 1wt.%). With this process, the wettability of composite solders was accepted although they were worse than that of Sn-58Bi. Compared with the spread area of Sn-58Bi, that of Sn-58Bi-1wt.% Cu 6 Sn 5 was reduced about 10% after reflowing for 30min. The reinforcement particles were well dispersed in the solder matrix and refined the grain size of β-Sn and Bi-rich phase. During the liquid interfacial reaction, the size of interfacial IMC was increased with reflowing time and it got larger for the addition of Cu 6 Sn 5 . The shear strength of composite solder joints was higher than that of Sn-58Bi/Cu. The fracture modes of composite solder were mainly ductile while that of Sn-58Bi/Cu was brittle when ε̇ =9×10 -3 s -1 .

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