Sn60Pb40, Sn63Pb37, Sn55Pb45, Sn50Pb50, Sn45Pb55, Sn40Pb60, Sn35Pb65, Sn30Pb70, Sn25P75 Even and bright welding spot, favorable diffusion performance, no corrosion, no pungent smell, and no harm for integrate circuit or sensitive electronic elements; applied to frontier technologies in the fields of aviation, electronics, military industry, communication, and computer, etc.