Development of a lead‐free solder: Sn‐4.0Bi‐3.7Ag‐0.9Zn
Abstract
Purpose
The purpose of this paper is to study the relationship between microstructure and mechanical properties of Sn‐4.0Bi‐3.7Ag‐0.9Zn (in wt%) solder, and the structural evolution of the soldered interfaces.
Design/methodology/approach
The solder was prepared by a vacuum arc furnace. Scanning electron microscopy (SEM) and X‐ray diffraction were used to identify the microstructure and composition. The melting temperature, microhardness and tensile strength were measured. Solder joints were prepared by reflowing at 250°C for 1 min in a vacuum oven and the soldered interfaces were observed by using SEM.
Findings
The microstructure of the slowly cooled Sn‐4.0Bi‐3.7Ag‐0.9Zn specimen is composed of bulk Ag3Sn, AgZn intermetallic compounds (IMCs), Bi precipitates and a β‐Sn phase. The developed solder exhibits good comprehensive properties, such as low‐melting temperature, high microhardness and ultimate tensile strength. A complicated IMC layer forms at the interface with Cu pads and it turns into a thinner Ni3Sn4 layer with Ni/Cu substrates.
Originality/value
The paper shows how a high performance, lead‐free solder was developed.
Keywords
Citation
Wang, X., Liu, Y., Yu, L., Dong, Z. and Gao, Z. (2011), "Development of a lead‐free solder: Sn‐4.0Bi‐3.7Ag‐0.9Zn", Soldering & Surface Mount Technology, Vol. 23 No. 1, pp. 15-21. https://doi.org/10.1108/09540911111099668
Publisher
:Emerald Group Publishing Limited
Copyright © 2011, Emerald Group Publishing Limited