PURPOSE: To easily and collectively form metal balls having a steep distribution of grain size by heating a supporting base material and melting an alloy with a low melting point or a metal paste having metal as a main composition which is filled in the recessed part of the material.
CONSTITUTION: At first, the alloy with a low melting point or the metal paste 2 with metal as the main composition is filled in the recessed part provided on the face of the supporting base material 1 by sliding a squeegee 3. Then, the supporting base material 1 is heated to 230°C by means of a heating head 4, the filled metal paste 2a is melted, and metal balls 2b are collectively formed. Also, by adding ultrasonic wave or a mechanical minute vibration while the supporting base material 1 is heated, the metal grains in the recessed part can all be aggregated, and the uniform metal balls 2b are obtained highly efficiently.
HATAKEYAMA AKIHITO
HORIO YASUHIKO
