| It is a certain tendency that the lead-free solder is used in the electronics package. Especially, for China, it falls behind the developed countries in the lead-free solder development. For us, it is very important to possess patent with the lead-free solder content for our electrical product going in international market. The purpose of this research is to develop a new and low-cost lead-free solder. Therefore, the Sn0.7Cu solder alloy was investigated in the paper by the addition of Ni and Re, to get a better solder than Sn0.7Cu.In the research, the microstructure of the alloys and solder interface are observed, and some properties including conductivity property, melting, oxidization, corrosive, mechanical properties, wetting, shearing are tested. The relationships between the characteristic of the solder alloy and the concentration of Ni and Re are further analyzed theoretically.The results indicated that, with the addition of Ni, the microstructure of the solder alloys gets finer, the thickness of the solder interface gets thinner, the hardness and tensile strength are enhanced. The conductivity decreases, the melting point increase and the melting interval is wider. With the addition of Ni, oxidization and corrosive are not changed. Below 0.3wt% with the addition of Ni, the wetting and shearing properties are better. Above 0.3wt%, they are worse. With the addition of Re, the crystal grain of the solder alloys gets finer, the thickness of the solder interface gets thinner, the hardness and tensile strength are enhanced, the anti-oxidization and the anti-corrosive are better. The melting point increase, the melting interval is wider, Below 0.05wt% with the addition of Re, the wetting, the conductivity and the shearing are better. Above 0.05wt%, they are worse. For this research, the best content of the lead-free solder is Sn0.7Cu0.3Ni0.05Re, it has best mechanical properties and wetting properties for these solders.
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