Prediction of mechanical properties on zinc system alloys and their application to high temperature lead-free solder

The effectiveness of the electronic parameter was evaluated in order to predict the mechanical properties of zinc system alloys for high temperature application. Firstly, the relation of ultimate tensile strength or elongation and s-orbital energy level (Δ Mk) of already reported Zn system multicomponent alloys were investigated. According to this relation, the lead-free Zn-Al-Sn system alloys have been proposed in order to satisfy both the tensile strength of 200 MPa and elongation of 5 %. Promising compositions of alloys were Zn-4Al-7Sn, Zn-10Al-0.5Sn and Zn-10Al-2Sn in mass % and their Δ Mk values were 0.079, 0.080 and 0.089, respectively. Proposed alloys showed tensile strength of 195-225 MPa depending on increment of Δ Mk values, and elongation of 4.5-5.1 %. The optimization of compositions on Zn alloys was found to be speedy and precisely achieved using the Δ Mk 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 devices packages, etc. In addition, the contact angles between Cu plate and the proposed alloys Zn-4Al-7Sn, Zn-10Al-0.5Sn and Zn-10Al-2Sn at 973 K in the Ar stream are 33.8°, 73.5°and 50.1°, respectively.