Effect of Ag and Ni on melting temperature and spreadability of Sn-SbCu solder alloy

In order to improve the properties of the Sn-10Sb-8Cu solder alloy, two new lead-free solders(Sn-Sb-Cu-Ag and Sn-Sb-Cu-Ni) were made by adding small amounts of Ag and Ni into Sn-10Sb-8Cu solder alloy.Results show that the melting temperatures of the Sn-Sb-Cu-Ag solder alloys decrease and the spreading areas increase compared with those of the matrix solders, which are related to the increase of the superheat degree, the dispersed distribution of SnAg phase with low melting point and the decrease of the surface tension of the melting solder.The melting temperatures of the Sn-Sb-Cu-Ni solder alloys decrease and the spreading areas of the Sn-Sb-Cu-Ni solder alloys are slightly less than those of the matrix solders. It is because the viscous and the surface tension of the Sn-Sb-Cu-Ni melting solder increase and the Cu₆Sn₅ is covered by the polyhedron-shape(Cu,Ni)₆Sn₅ which is adverse to the spreadability of the solder by adding small amount of Ni.