Evolution of nano-Ag₃Sn particle formation on Cu–Sn intermetallic compounds of Sn3.5Ag0.5Cu composite solder/Cu during soldering

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• 作者：L.C. Tsao ; ^a ; ^{tlclung@mail.npust.edu.tw}
• 关键词：Ag₃Sn ; Sn3.5Ag0.5Cu ; Cu₆Sn₅
• 刊名：Journal of Alloys and Compounds
• 出版年：2011
• 出版时间：3 February 2011
• 年：2011
• 卷：509
• 期：5
• 页码：2326-2333
• 全文大小：2008 K

文摘

A Sn3.5Ag0.5Cu–0.5nano-TiO₂ composite lead-free solder was prepared by adding 20 nm TiO₂ to Sn3.5Ag0.5Cu (wt. % ) solder. This study investigates the morphology of the intermetallic compounds (IMCs) formed during the soldering reactions between Sn3.5Ag0.5Cu–0.5nano-TiO₂ solder and Cu substrates at various temperatures ranging from 250 to 325 °C. The Cu₆Sn₅ grains formed in all soldering below 300 °C were scallop-type, while those formed at both 300 °C and 325 °C were prism-type in the early stage of soldering (less than 30 min). Also, Cu₆Sn₅ grains that formed at both 300 °C and 325 °C changed from prism-type to scallop-type with increasing soldering time. It is quite interesting that the morphology of Cu₆Sn₅ grains affects absorption by nano-Ag₃Sn particles. Especially, the scallop-type Cu₆Sn₅ grains formed by the ripening process are likely to be “captured” by the large amount of nano-Ag₃Sn particles.

These nanoparticles apparently decrease the surface energy and hinder the growth of the Cu₆Sn₅ IMC layer. In addition, the grain size of the nano-Ag₃Sn compounds increased with increasing soldering temperature and time. All these results indicate that Gibbs absorption theory can be used to explain the formation of these nanoparticles and their effects on the surface energy of the IMCs.