The Effects of Small Additions Ga and Al on the Microstructure and Tensile Properties of Sn-Zn Based Lead-Free Solders

Abstract:

The melting temperature, microstructures, and mechanical properties of the Sn-Zn-0.5Ag-0.5Ga, Sn-Zn-0.5Ag-0.45Al and Sn-Zn-0.5Ga-0.45Al lead-free solders were investigated. The results indicate that the addition of 0.5 wt% Ag to the Sn-Zn based alloys destroy the eutectic structure and results in the formation of Ag-Zn compound and hypoeutectic structure. The variation in the microstructure lowers the UTS. By the addition of Al the UTS and elongation of the 0.5Ag-0.45Al alloy can be decreased due to the Al diffused to the interface of the Ag-Zn compound/Sn-Zn eutectic structure to form Al-Zn compound. The 0.5Ga-0.45Al alloy shows a typical eutectic structure with the light contract β-Sn and the darker needle-like phase, as well as a small amount of Al-Zn phase with a near diamond shape. Gallium uniformly distributes in the Sn matrix and Zn rich phases. The 0.5Ga-0.45Al solder had the highest UTS and elongation, while 0.5Ag-0.45Al had the lowest UTS and elongation. The results indicate that Ga and Al exhibits prominent influence on the microstructure as well as the mechanical properties of the solders.

• Periodical: Advanced Materials Research (Volume 800)
• Pages: 265-270
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.800.265
• Online since: September 2013
• Authors: Kang I Chen, Shou Chang Cheng, Chin Hsiang Cheng
• Keywords: Lead-Free Solder, Microstructure, Sn-Zn, Tensile Properties

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