| 摘要 |
A multilayer printed wiring board includes a first insulating layer, a pair of second insulating layers sandwiching therebetween the first insulating layer, a pair of internal-layer wiring trace formed between the first insulating layer and the second insulating layer, and an external-layer wiring trace formed on the exposed surface of the second insulating layer. A hollow cylindrical via-plug is formed on the inner wall of a first through-hole penetrating through the first insulating layer and connects together the internal-layer wiring traces with each other. A second via-plug formed inside the first via and isolated therefrom by insulating resin connects together the external-layer wiring traces.
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