| 摘要 |
PROBLEM TO BE SOLVED: To improve wiring efficiency and reduce wiring length, by a method wherein, after a wiring layer is covered with an insulating resin layer, a viahole is formed, a plating block is grown in the viahole, and a viapad is formed. SOLUTION: An insulating resin layer 2 is formed on a resin board 10 on which a wiring pattern containing a viapad 3 is formed. A viahole reaching the viapad 3 on the surface layer of the resin board 10 is bored. The viahole is plated with electrolytic copper, and the viahole is filled with a plating block 5. The forming process of the plating block 5 is performed until the plating block 5 protrudes from the insulating resin layer 2. Then polishing is performed until the surface layer height of the plating block 5 becomes equal to the wiring pattern on the insulating resin layer 2, the viahole pad 3 is formed, and a build up layer 1' is formed. By repeating the similar processes, a plurality of build up layers 1, 1" can be formed. |
