Lead-free solder balls and method for the production thereof
AssigneeSenju Metal Industry Co., Ltd.
InventorsRikiya Kato, Shinichi Nomoto, Hiroshi Okada
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Abstract
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.
Claims7
Lead-free solder balls for forming solder bumps on a substrate, the composition of the solder balls consisting of 4.0% to 6.0% by weight of Ag, 1.0% to 2.0% by weight of Cu, and a balance of Sn, the solder balls having a diameter of from about 0.05 mm to about 1.0 mm.
A method for producing lead-free solder balls comprising the step of forming a molten alloy composition which consists of 4.0% to 6.0% by weight of Ag, 1.0% to 2.0% by weight of Cu, and a balance of Sn into solidified balls having a diameter of from about 0.05 mm to about 1.0 mm using the surface tension of the molten alloy.
Dependencies are inferred from the claim text.