The invention relates to a lead-free
solder alloy for
welding the electronic elements and its manufacturing method. The lead-free
solder alloy is characterized in that the main components are Sn, Ag, Cu, and Ni, and In, Bi, Pd, P, Ge, Ga, Se, Te, La, Ce, Pr, Nd, Pm, Sm, Eu, Tm are added selectively. The preparation method is characterized by taking Sn, Ag, Cu, Ni and the additional elements in proportion and
smelting them at the temperature of 1300 C. to 1500 C. to obtain the intermediate
alloy by using water glass covering process; melting the residual Sn and the intermediate
alloy at the temperature of 300 C. to 350 C. by using water glass covering process, and
casting the molten materials into
alloy pig and
soldering tin rod at the temperature of between 250 C. and 350 C.. The lead-free
solder alloy provided by the invention can be used for
welding the Ag and Pd
noble metal electronic element.