| abstract |
Provided is a circuit board which is excellent in smoothness and capable of reducing the transmission loss of a high frequency electric signal. The circuit board according to the present invention comprises a wiring portion and a non-wiring portion, the wiring portion having a metal layer and a resin layer, the non-wiring portion having a resin layer, and the frequency of the resin layer at 23 ° C. Assuming that the relative dielectric constant at 10 GHz is 2 to 3, the maximum value of the thickness in the wiring portion is A (μm), and the minimum value of the thickness in the non-wiring portion is B (μm). B) It is characterized by satisfying the relationship of /B≦0.1. |