| 摘要 |
PROBLEM TO BE SOLVED: To form solder bumps having a uniform height, when the arranging pitch of pads and the diameters of the pads are narrow and small and to accurately supply solder balls to the pads even if the solder balls have very small diameters of about 105 μm. SOLUTION: In a method for forming solder bump, a metal mask 52, having openings in each of which one solder ball 66 can be put at the positions corresponding to pads, is placed on a holding base 64 and many solder balls having prescribed diameters are put on the mask 52 and respectively dropped in the openings 62 by rubbing the surface of the mask 52 with a squeegee 68. Then the mask 52 is closely adhered to the holding base 64 and a printed wiring board is placed on the mask 52, by aligning the pads of the printed wiring board with the openings 62 of the mask 52. After the wiring board is placed on the mask 52, the solder balls are press-contacted with the pads, by uniformly pressing the wiring board toward the holding base 64 from the wiring board side, and after flux is adhered, solder bumps are formed on the pads by melting the solder balls through the heating of the balls in a reflow furnace. |
