COPPER BALL AND METHOD FOR PRODUCING THE SAME

摘要

A Cu ball superior in mass productivity which is effective as a bump for packaging a semiconductor of a BGA (Ball Grid Array) type and having a high dimensional precision, and a method for producing the same ball. In order words, Cu wires are cut to a standard size and obtained Cu pieces each having predetermined diameter and length are degreased, and then they are disposed in a plurality of holes having predetermined diameter, depth, and surface roughness and formed in a flat individual piece disposing fixture. Then, both the individual piece disposing fixture and individual Cu pieces are heated to be fused in an electric furnace, and then they are cooled at a predetermined cooling speed so that the Cu pieces are solidified into a ball due to the surface tension of fused metal itself, whereby in the case of Cu balls having a final diameter of 2mm or less which is obtained after having been fused and solidified, the sphericity of 90 % or more of Cu balls obtained at the same time is within 3 % of the diameter, and a solder layer or a silver solder layer is applied and formed on the outer circumferential surface of the Cu balls as required.