| 摘要 |
PROBLEM TO BE SOLVED: To increase the area of a circuit pattern by successively repeating the lamination of an insulating layer, filling up holes with conductive paste, and the formation of a circuit pattern. SOLUTION: After a circuit pattern 3 is formed on a first insulating layer 2, a sheet-like second insulating layer 6 made of the same material as that of the layer 2 and having previously bored holes 6a is laminated upon the layer 2 and pattern 3 and conductive paste 7 is put and hardened in the holes 6a. The holes 6a are formed through the layer 6 at the locations where the circuit pattern 3 on the layer 5 is electrically connected to a circuit pattern 8 formed on the layer 6. Then the desired pattern 8 is formed on the layer 6. A third insulating layer 11 also having previously bored holes 11a is laminated upon the lower surface of a core material 1 and conductive paste 13 is put and hardened in the holes 11a. Similarly, a fourth insulating layer 15 is laminated upon the third insulating layer 11. Therefore, the need of forming through holes through each layer is eliminated and the area of the circuit pattern of each layer can be increased without any restriction. |
