CIRCUIT BOARD AND MANUFACTURING METHOD THEREOF

To provide a circuit board which can eliminate influence of environmental humidity in use as much as possible, and in which an insulating resin layer can maintain the initial dielectric properties for a long period of time.SOLUTION: A circuit board 101 includes: an insulating resin layer 10; a patterned circuit wiring 21 provided in the insulating resin layer 10; and a barrier film 50 which covers at least a portion of an exposed surface of the insulating resin layer 10 and suppresses moisture absorption of the insulating resin layer 10. The barrier film 50 is made of a material having a low moisture transmittance and has a function of preventing moisture from entering into the insulating resin layer 10. At least the portion of the exposed surface of the insulating resin layer 10 may be covered.SELECTED DRAWING: Figure 1 【課題】使用中の環境湿度の影響を極力排除することが可能で、絶縁樹脂層が初期の誘電特性を長期間にわたって維持できる回路基板を提供する。【解決手段】回路基板１０１は、絶縁樹脂層１０と、絶縁樹脂層１０中に設けられているパターン形成された回路配線２１と、絶縁樹脂層１０の露出面の少なくとも一部分を覆い、該絶縁樹脂層１０の吸湿を抑制するバリア膜５０と、を備えている。バリア膜５０は、水分透過率が低い材質で構成され、絶縁樹脂層１０中への水分の侵入を防ぐ機能を有する膜であり、絶縁樹脂層１０の露出面の少なくとも一部分を覆っていればよい。【選択図】図１