The Properties Of New Lead-free Solder Sn-Sb-Cu-Ni

Demands of using lead-free solder will become a tendency with the concept of Green Earth in the whole world. Now, it is generally considered that Sn-Ag-Cu solder is the most potential alternative to Sn-Pb solder. However, Sn-Ag-Cu solder is expensive as silver is rare, which limits its extensive application. In order to decrease the costs, in this paper, a new solder is researched, which is based on Sn-Ag-Cu solder and uses element Sb as a replacement for Ag. In addition, a certain proportion of Ni is also joined. Compared with Sn-Ag-Cu system and Sn-Pb system, Determine the best ratio. The main contents of the paper is as follows:melting point, resistivity,wettability,thermal conductivity, Tin melting rate, dryness,tensile strength, shear strength.Considering lots of electronic products and solders will suffer from low temperature when they are exported by ship. So the low temperature condition is simulated and properties of this new solder are studied in this condition, such as electric conductivity, mechanical property.The results show that:Either before or after welding,the electrical conductivity of Sn-Sb-Cu-Ni alloys increased with increasing Sb content, when the Content of Sb increased to 4.5%, The conductivity is best, then began to decline; New solder thermal conductivity and electrical conductivity have a similar variation.Compared with Sn-Ag-Cu system, the wettability and solder joints shear strength of Sn-Sb-Cu-Ni system significantly improved, slightly higher tensile strength of solder joints, However, slightly higher melting point.The electrical conductivity of SnSb4.5Cu1.5Ni under low and normal temperature was greater than that of Sn63Pb37.The tensile and shear strength of them decreased when the temperate decreased, however the strength then improved when the temperature dropped to -20℃. In addition, SnSb4.5Cul.5Ni was ductile fracture, Sn63Pb37 was brittle fracture and SnAg3.0Cu0.5 was mixed fracture at low temperature. Therefore,the abOve analysis,containing Sb3%-6% range,when the Sb 4.5%,the overall performance is relatively good,which is the best ratio of required.