| EU Rolls (Restriction on Hazardous Substance) legislation comes into effect in July1st 2006,which forbids using Pb,Hg,Ge, Cr6+, PBB,PBDE in Electron product,and compelthe study of lead-free solder come into application. SnAgCu lead-free solder which haseximious comprehensive performance is deemed to the promising of solder in the substitut:of SnPb.Comparing with SnPb solder,SnAgCu has the high melting point, bad wetting property,high cost and so on, which affecting the development of SnAgCu. In this book,we addGa,Bi in SnAgCu, and optimize the Ag content and analyze their melting temperature,wetting property, mechanical property and microstructure, and educe the followingconclusion:(1) Adding Ga into SnAgCu can reduce the melting temperature, with increasing content ofGa, the solidus and liquidus of alloys reduce unceasingly, especially the solidus.This canincrease the solder melting range, and make against the solder flow. With increasing contentof Ga, the wetting property reduces unceasingly. When the content of Ga increase 1％, thespreading area reduces 10～15％.(2) Adding Bi into SnAgCuGa can reduce the lead-free solder melting temperature.When the content of Bi exceeds 2％, the liquidus of alloy lessening is not very obvious. Andadding Bi can improve the wetting property. When the content of Bi is less than 2％, thewetting property is improved unceasingly. Whereas, when the content of Bi is more than 2％, the wetting property is reduced.(3) Changing the content of Ag on the basis of SnAgCuGaBi,When the content of Ag is lessthan 2.5％,with the increasing content of Ag,the melting temperature is reduced. And themelting temperature will increase with the increasing of the Ag content under the condition ofthe Ag content more than2.5％.And the wetting property of lead-free solder is the best whenthe content of Ag is 2.5％.(4) The mechanical property of New Lead-free Solder is prior to SnAgCu.and the price ofnew lead-free solder is less than SnAgCu.
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