Patent ID: 10354944

Abstract:
A method for soldering a surface-mount component onto a circuit board. The melting of die-bonding solder material is prevented by using a mounting solder material when soldering a surface-mount component formed using the die-bonding solder material onto a printed circuit board. The surface-mount component, formed using (Sn—Sb)-based solder material having high melting point, the (Sn—Sb)-based solder material containing Cu but not more than a predetermined quantity of Cu constituent and a main ingredient thereof being Sn, is soldered on a board terminal portion of a circuit board using (Sn—Ag—Cu—Bi)-based solder material or (Sn—Ag—Cu—Bi—In)-based solder material as the mounting solder material and with the solder material being applied on the terminal portion. Since solidus temperature of the die-bonding solder material is 243 degrees C. and liquidus temperature of the mounting solder material is about 215 through 220 degrees C., the melting of die-bonding solder material is prevented even at the heating temperature (240 degrees C. or less) of a reflow furnace.