Patent ID: 11628519

Abstract:
A solder joint, for bonding an electrode of a circuit board to an electrode of an electronic component, that includes: an Sn—Bi-based solder deposited on the electrode of the circuit board; and a solder alloy deposited on the electrode of the electronic component. The Sn—Bi-based solder alloy has a lower melting point than the solder alloy deposited on the electrode of the electronic component. Fine Bi phases in the solder joint each have an area of less than or equal to 0.5 μm2. Coarse Bi phases in the solder joint each have an area of greater than 0.5 μm2 and less than or equal to 5 μm2. A proportion of the fine Bi phases among the fine Bi phases and the coarse Bi phases is greater than or equal to 60%.