| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of a solder ball by removing the position part of inner wall face plating on a side opposite to a part linked with the pads of a pair of build-up layer via holes which are adjacent to respective facing sides of the rectangular pads and whose part in inner walls are linked with the pads. SOLUTION: A part of copper plating in via holes 5 linked with pads 4 is remold and via hole inner wall parts where resin is exposed are formed. Solder paste sticking out of the pads 4 of a printed wiring board 1 is accumulated in the via holes 5 adjacent to pads. At the time of reflow heating, solder in the via holes 5, which is changed from solder paste into melting solder, is not bonded o resin walls 7 since a part of the via hole inner walls is resin. The necessary quantify of solder can be supplied for the soldering of the pads 4 of the printed wiring board 1 and the electrodes 6 of a chip 2. Remaining melting solder 3 can be attracted to the conductors of the via holes 5 and the occurrence of a solder ball can be prevented.
|
