| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit board which can improve the effects of characteristic impedance and crosstalk noise by shielding inner wiring patterns with power supply/ground layers, and at the same time, can be formed into a small thickness. SOLUTION: A circuit board 4 is constituted in such a way that inner wiring patterns 2 are formed on both surfaces of a core substrate 1 and power supply/ ground layers 5 are respectively formed on the patterns 2 through insulating resin layers 3, and electronic parts 7 can be mounted on the patterns 2 exposed in recessed sections 6 formed, when the insulating resin layers 3 are removed through dry etching.
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