Papers by Keyword: Sn-Zn

Abstract: In this paper, the effect of thermal aging to the Sn-Zn and Sn-Zn-Bi solders on Cu substrate was studied. Sn-Zn was chosen and the effect of addition of Bi was investigated in this work. In this research, Sn-9Zn and Sn-6Zn-4Bi were subjected to thermal aging for 24h, 72h, 120h at 75°C and 100°C respectively. Both solder shown increased of thickness intermetallic layer with increasing time. However, Sn-9Zn recorded higher increment of intermetallic layer compared to Sn-6Zn-4Bi. The hardness of solder joint on Cu substrate was decreased for both solders with increasing aging time.

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.

Abstract: This work presents the studies of wettability Sn-6Zn-4Bi lead-free solder alloy in electronic applications. A reference solder Sn-3.1Ag-0.9 Cu lead-free solder alloy is used to compare the properties of both solders. Differential Scanning Calorimeter (DSC) profile, wettability and the microstructure of the solder were investigated. The melting temperature of Sn-Zn-Bi (Tm=194.97°C) is lower than Sn-Ag-Cu (Tm=220.40°C). Further, the wettability between molten solder and copper substrate was measured at different reflow temperature. The contact angle for Sn-Ag-Cu was decreasing from 28.23º to 24.97º and for Sn-Zn-Bi solder alloys were decreasing from 48.92º to 29.78º as the temperature increased from 230°C to 250°C. A significant increment of contact angle for Sn-Zn-Bi at 270°C and the contact angle did not change at 270°C for Sn-Ag-Cu. The result of spreading area is inversed with the contact angle. The layers of intermetallic compound were examined by energy-dispersive X-ray. The Sn-Zn-Bi solder exhibits a mixture of Cu-Sn+Cu-Zn phase and ϒ-Cu₅Zn₈ phase. The Sn-Ag-Cu solder exhibits Cu6Sn5 (η-phase) and Cu3Sn (ε-phase). As a conclusion, Sn-Zn-Bi is a potential lead-free solder to develop based on its wettability properties than previous available solder materials.

Abstract: A new process, melts dispersion technique, was developed to fabricate the solder powder in oil surroundings by forming molten metal’s droplets. The main parameters of the technique on shape and size of powders were investigated in the present paper. It is shown that a cooling rate of the melts and viscosity of oil for isolation of droplets affect the shape and the size. The cooling rate is a very important parameter, and there is a critical cooling rate at given conditions. Although the melts were dispersed perfectly in oil, fine droplets were merged and coalesced during solidification without rapid cooling. The shape of powder has an influence mainly on oil viscosity and was altered into a sphere from an irregular shape with increasing oil viscosity.