2014 Volume 86 Issue 3 Pages 216-222
In this study, lead-free Zn-Al-Sn solders for high-temperature applications were proposed using s-orbital energy level (ΔMk) in order to satisfy both the tensile strength of 200MPa and elongation of 5%. Promising compositions of alloys were Zn-4Al-7Sn, Zn-10Al-0.5Sn, and Zn-10Al-2Sn in mass% and their ΔMk values were 0.079, 0.080 and 0.089, respectively. Their ingots were produced and tensile tested at 293K in air. The proposed alloys showed tensile strength of 195 - 225MPa depending on the increment of ΔMk values, and elongation of 4.5 - 5.1%. Optimization of compositions on Zn alloys was found to be speedy and precisely achieved using the ΔMk parameter. The proposed alloys also showed liquidus temperatures of 645-700K, indicating that the high temperature lead-free solders can be applied for power semiconductor device packages, etc. In addition, contact angles of 33.8° and 73.5° at 973K in Ar stream were seen between Cu plate and the proposed alloys Zn-4Al-7Sn and Zn-10Al-0.5Sn, respectively, suggesting that the proposed alloys can be practically applied at high temperatures.
