The bulk alloy microstructure and tensile properties of Sn‐1Ag‐0.5Cu‐xAl lead‐free solder alloys (x=0, 1, 1.5 and 2 wt.%)

Abstract

Purpose -The purpose of this paper is to investigate the effect of Al addition on the bulk alloy microstructure and tensile properties of the low Ag-content Sn-1Ag-0.5Cu (SAC105) solder alloy. Design/methodology/approach -The Sn-1Ag-0.5Cu-xAl (x ¼ 0, 1, 1.5 and 2 wt.%) bulk solder specimens with flat dog-bone shape were used for tensile testing in this work. The specimens were prepared by melting purity ingots of Sn, Ag, Cu and Al in an induction furnace. Subsequently, the molten alloys were poured into pre-heated stainless steel molds, and the molds were naturally air-cooled to room temperature. Finally, the molds were disassembled, and the dog-bone samples were removed. The solder specimens were subjected to tensile testing on an INSTRON tester with loading rate 10 2 3 s 2 1 . The microstructural analysis was carried out using scanning electron microscopy/Energy dispersive X-ray spectroscopy. Electron Backscatter Diffraction (EBSD) analysis was used to identify the IMC phases. To obtain the microstructure, the solder samples were prepared by dicing, molding, grinding and polishing processes.Findings -The addition of Al to the SAC105 solder alloy suppresses the formation of Ag 3 Sn and Cu 6 Sn 5 IMC particles and leads to the formation of larger Al-rich and Al-Cu IMC particles and a large amount of fine Al-Ag IMC particles. The addition of Al also leads to refining of the primary b-Sn grains. The addition of Al results in a significant increase on the elastic modulus and yield strength. On the other hand, the addition of Al drastically deteriorates the total elongation. Originality/value -The addition of Al to the low Ag-content SAC105 solder alloy has been discussed for the first time. This work provides a starting-point to study the effect of Al addition on the drop impact and thermal cycling reliability of the SAC105 alloy.

Effect of Al addition on microstructure and wetting properties of quinary lead-free solder alloy systems

“…The literature has reported that the primary CuSn phases related to Al-added SAC solder alloys are inhibited, and the groups of Al content suppress the CuSn steps It was observed that β-Sn, CuAl, and SnCu phases were formed in regions close to the Cu 6 Sn 5 phase. When the SEM analyses were examined, the intermetallic components formed at the interface became more prominent as the temperature value increased for each lead-free solder alloy [33][34][35].…”