Patent ID: 8119516

Claim:
A method for forming a bump structure for conductive interconnection with another element that has at least one of microelectronic devices or wiring thereon, wherein the bump structure is used as an electric connection in an electronic circuit, comprising the steps of: forming a mandrel by steps including: forming at least one opening extending through a bump-forming die body in a thickness direction thereof, the bump-forming die body being comprised of a metal sheet; and positioning a bump-forming die lid on a surface of the bump-forming die body so as to cover one end of the opening to form the mandrel that includes the bump forming die body and the bump-forming die lid and to thereby define a bump-forming recess in the mandrel; forming a metal layer at least on an inner surface of the bump-forming die lid exposed within the bump-forming recess; and removing the mandrel so as to expose the metal layer and form the bump structure.