| 摘要 |
PURPOSE:To improve the reliability of a multilayered wiring board by forming a blind through hole in such a way that a hole is bored to the through hole entrance section of an inner-layer circuit board with a drill and the inner surface of the hole is coated by chemical plating. CONSTITUTION:A through hole 13 is formed through an outer-layer wiring board 14 and another through hole 16 is formed through an inner-layer wiring board 18. Then a multilayered wiring board 22 is formed by sticking the inner- layer 18 thus formed to another inner layer 18 with a bonding agent 19 in between under a pressure. After forming the board 22, a hole is bored with a drill 23 to connect the through holes 16A and 16B to each other. The boring work can be completed when the front end 24 of the drill 23 reaches the vicinity of the entrance 25. After the hole is bored, the inner surface of the hole is coated by chemical plating and a through hole 16 is formed. Then the multilayered wiring board 22 is put on another wiring board 22 and a blind through hole 16 is formed between the two multilayered wiring board. |
