Development ofPb-free SolderAlloys Using the Melting Temperature Estimation Method for Sn Alloys

Sn-Pb合金目前在电气和电子工业中用作焊料。然而，近年来，有人声称焊料中含有的有毒Pb可能污染环境。无铅钎料合金的开发已引起各国的重视。本研究的目的是利用目前研究者发现的熔化温度与合金成分之间的有趣关系来开发一些无铅焊料合金，在第一年中，设计了17种含有Ag、Bi、Zn和In的Sn基合金作为第一步候选合金。所有这些都被设计为具有与Sn-Pb焊料相同的熔化温度，456 K。实验测得的这些合金的熔化温度在453- 466 K之间，这一结果支持了熔化温度估算方法的有效性。 关于我们 这对于第二步候选合金的设计是必要的。研究了合金元素Zn、Ag、Cd、In、Sb、Pb和Bi对锡基合金硬度、电阻率、晶格常数和润湿性的影响。结果表明，所有合金元素的加入都提高了锡合金的硬度和电阻率。在这些元素中，由于Sn晶格的大畸变，Bi具有最大的硬化效果。研究发现，Pb、Ag、Bi的加入可改善Sn合金与铜板的润湿性。利用所获得的半定量信息，设计了6种含Ag和In的Sn-Zn和Sn-Bi基合金。结果表明，Sn-Zn基第二候选合金具有与Sn-3.5Ag-0.7Bi合金相似的力学性能，Sn-3.5Ag-0.7Bi合金是下一代无铅焊料最有前途的合金。此外，锡铋基候选合金具有与铜板相当的润湿性。基于这些实验，它表明，无铅焊料合金可以有效地开发采用本熔化温度估计方法。少

Sn-Pb alloys are used currently as a solder in electrical and electronic industries. In recent years, however, it has been claimed that there is a possibility of polluting the environment with toxic Pb contained in the solder. Much attention has been paid to the development of Pb-free solder alloys in various countries. In this study, it was aimed to develop some Pb-free solder alloys utilizing an interesting relation between the melting temperature and the alloy composition which was discovered by present investigator.In the first year, 17-types Sn-based alloys containing Ag, Bi, Zn and In were designed as the first step candidate alloys. All of them were designed so as to have the same melting temperature as that of Sn-Pb solder, 456K. Measured melting temperatures of these alloys were within the range of 453-466K, and this results supported the usefulness of the melting temperature estimation method.In the second year, some fundamental experiments were made in order to obtain inform … More ation which is necessary for the design of second step candidate alloys. The effect of alloying elements, Zn, Ag, Cd, In, Sb, Pb and Bi on the hardness, electrical resistivity, lattice constant and wettability of Sn based alloy was measured. It was shown that the addition of all alloying elements increased the hardness and resistivity of Sn alloys. Among these elements, Bi has the largest hardening effect due to the large distortion of Sn crystal lattice. The addition of Pb, Ag, Bi was found to improve the wettability of Sn alloys with copper plate. By using obtained semi-quantitative information, 6-types of Sn-Zn and Sn-Bi based alloys containing Ag and In were designed. It was found that Sn-Zn based sencond candidate alloys had similar mechanical properties to those of Sn-3.5Ag-0.7Bi, the most promising alloy as Pb-free solder for the next generation. Also, Sn-Bi based candidate alloys had equal wet-ability with Cu plate. Based on these experiments, it was demonstrated that Pb-free solder alloys could be developed efficiently by employing the present melting temperature estimation method. Less