| abstract |
(57) [Summary] (Correction) [PROBLEMS] To provide a 4-layer printed wiring board which is thin, has a small variation in thickness, and has a smooth surface and suitable for high-density mounting. A four-layer printed wiring board is formed by sequentially laminating an optical / thermosetting undercoat layer, an interlayer insulating adhesive layer, and a copper foil on both surfaces of an inner layer circuit board made of a flame-retardant epoxy resin-impregnated glass cloth substrate. |