PURPOSE: To prevent solder bumps and electronic components from being excessively stressed at the time of mounting the electronic components on a circuit board by arranging the solder bumps containing elastic cores on the electrodes of the circuit board.

CONSTITUTION: After forming aluminum electrode pads 12 on a semiconductor substrate 11, the substrate 11 is coated with an insulating layer 14 composed of a silicon nitride film and electrode sections 70, each of which is composed of a barrier metal 71 of titanium, chrome, etc., and a copper layer 72 formed on the metal 71, are formed on the pads 12. A solder bump 80 formed on each electrode section 70 is constituted of a core composed of a polyimide resin ball 81, nickel 82 coating the ball 81, and solder (S) coating the entire surface of the ball 81. The ball 81 has elasticity and can stand 200-300°C, because the ball 81 is formed of a polyimide resin.