Lead-free solder balls having a good surface appearance with no appreciable surface defects such as seams and shrinkage cavities comprises an alloy having a composition consisting essentially of about 4.0% to about 6.0% by weight of Ag, about 1.0% to about 2.0% by weight of Cu, and a balance of Sn, and they have a diameter of from 0.05 mm to 1.0 mm. The solder balls can be produced by forming a molten alloy having the above-described composition into solidified balls having a diameter of from 0.05 mm to 1.0 mm using the surface tension of the molten alloy.