LEAD-FREE WELD HAVING A LOW MELTING POINT AND ADDITIONS OF SILVER AND RARE EARTH FOR THE ELECTRONIC

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The present invention is intended to provide a lead-free welding alloy to the electronic industry for replacing the traditional Lead (Pb) 37%-Tin (Sn) 63% alloy, due to the lead toxicity for living beings and pollution produced by said element in soils and the phreatic surface. The present invention uses non-toxic elements or pollutants such as : Bismuth (bi) in a ratio of from about 57.2% to about 57.6%, Silver (Ag) in a ratio of from about 0.3% to about 0.7%, an element from rare earths selected from Pr and Nd in a ratio of from about 0.1% to about 0.001% and Tin (Sn) in a ratio completing a 100%. Said ratios are fixed; the alloys thereof have a melting point of 146.8°C when the selected rare earth element is Pr, and a melting point of 147.5°C when the selected rare earth element is Nd. Moreover, the contact angles are 7° when the selected rare earth element is Pr and 9° when the selected rare earth element is Nd.