Abstract:

The key problem of the current Sn-Ag-Cu lead-free solders is that their melting points are 34℃-38℃ higher than that of the traditional Sn-37Pb, both the soldering equipment and technology process have to be replaced. A novel low welting point solder is fabricated by adding microelements and using a  rapid solidification method based on the Sn-20Bi sold- er. The cost of the solder is much lower than that of Sn-Ag-Cu. Its mechanical and thermal properties, solderability and welting point are equivalent or superior to Sn-37Pb.

Key words: lead-free solder, low welting point, Sn-Bi-X, segregation, rapid solidification