PB-FREE SOLDER-CONNECTED STRUCTURE AND ELECTRONIC DEVICE

• Main Authors: NISHIMURA, ASAO, SOGA, TASAO, INABA, YOSHIHARU, OKUDAIRA, HIROAKI, NAKATSUKA, TETSUYA, SHIMOKAWA, HANAE, ISHIDA, TOSHIHARU
• Format: Patent
• Language: English; French
• Published: 01.08.2006
• Subjects: ALLOYS; BASIC ELECTRIC ELEMENTS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CHEMISTRY; 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; FERROUS OR NON-FERROUS ALLOYS; MACHINE TOOLS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; PERFORMING OPERATIONS; PRINTED CIRCUITS; SEMICONDUCTOR DEVICES; SOLDERING OR UNSOLDERING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WELDING; WORKING BY LASER BEAM

A Pb-free solder-connected structure having a sufficiently large connection strength, featuring an interface that remains stable even after the passage of time, and maintaining sufficient wettability and resistance against whiskers, and an electronic device. Specifically, a Pb-free solder, characterized in that an Sn-Ag-Bi solder which is a representative Pb-free solder is connected to an electrode that has an Sn-Bi layer formed on the surface thereof. Bi concentration in the Sb-Bi layer is preferably 1 to 20 % by weight to obtain a sufficient degree of wettability. When a more reliable joint is required, the Cu layer is formed under the Sn-Bi layer to obtain a connection portion having a sufficiently large interfacial strength.