Solder bonding method and solder joint

• Main Authors: Kosuga, Tadashi, Inaba, Ko, Takemasa, Tetsu
• Format: Patent
• Language: English
• Published: 24.08.2021
• 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 solder bonding method that bonds, using a solder joint, an electrode of a circuit board to an electrode of an electronic component includes: depositing, on the electrode of the circuit board, an Sn-Bi-based solder alloy with a lower melting point than a solder alloy deposited on the electrode of the electronic component; mounting the electronic component on the circuit board such that the Sn-Bi-based solder alloy contacts the solder alloy on the electrode of the electronic component; heating the circuit board to a peak temperature of heating of 150° C. to 180° C.; holding the peak temperature of heating at a holding time of greater than 60 seconds and less than or equal to 150 seconds; and cooling, after the heating and to form the solder joint, the circuit board at a cooling rate greater than or equal to 3° C./sec.