| 摘要 |
PROBLEM TO BE SOLVED: To provide a multilayer wiring board having high reliability by forming a through-hole for connecting a laminated second wiring pattern with a first wiring pattern on the board in a satisfactory shape. SOLUTION: An insulating layer 1 is formed on a board 10 on which a first wiring pattern 4 is formed so that the first wiring pattern 4 can be covered. Next, a conductive layer 6 is formed on the whole face of the insulating layer 1, and the conductive layer 6 above the first wiring pattern 4 is removed so that an opening 7 can be formed. Then, the insulating layer 1 is removed for making the first wiring pattern 4 visible from the opening 7 so that a continuity hole can be formed. Then, a second wiring pattern is formed while the conductive layer 6 in the surrounding of the opening 7 is left in the insulating layer 1, and a connection layer for connecting the first wiring pattern 4 with the second wiring pattern by plating or the like is formed in the continuity hole. A process for forming the continuity hole is executed by using a laser beam, and an opening diameterϕB is made larger than a laser beam diameterϕL. |
