Solder composition and method of bump formation therewith

• Main Authors: FURUNO MASAHIKO, ONOZAKI JUNICHI, HIRATSUKA ATSUSHI, SHIRAI MASARU, SAITO HIROSHI, SAKAMOTO ISAO, ANDO HARUHIKO
• Format: Patent
• Language: English
• Published: 09.08.2007
• Subjects: BASIC ELECTRIC ELEMENTS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; MACHINE TOOLS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; PERFORMING OPERATIONS; PRINTED CIRCUITS; SEMICONDUCTOR DEVICES; SOLDERING OR UNSOLDERING; TRANSPORTING; WELDING; WORKING BY LASER BEAM

A solder composition capable of in the bump formation on a substrate, simplifying the coating operation. There is provided solder composition ( 10 ) comprising a mixture of liquid substance ( 12 ) and solder particles ( 11 ), wherein the liquid substance ( 12 ) contains a flux component of organic acid whose reaction temperature for oxide film removal is in the vicinity of the melting point of the solder particles and has such a viscosity that the liquid substance flows at ordinary temperature and accumulates in the form of a layer on substrate ( 20 ). The solder particles ( 11 ) consist of a particulate agent that settles in the liquid substance ( 12 ) toward a solder base material, having a particle diameter and mixing ratio enabling uniform dispersion in the liquid substance ( 12 ). By application of this solder composition onto substrate ( 20 ) with pad electrode ( 22 ) followed by heating, solder particles ( 11 ) adhere to the pad electrode ( 22 ) having its surface oxide film removed through reaction with the flux component to thereby promote soldering between any solder film formed on the base material and the solder particles ( 11 ), and further, aggregation of the solder particles ( 11 ) can be inhibited by a reaction product of the flux component to thereby form unbridged solder bumps ( 23 ).