| abstract |
A circuit board having excellent smoothness and capable of reducing transmission loss of a high-frequency electric signal is provided. A circuit board according to the present invention includes a wiring portion and a non-wiring portion, wherein the wiring portion includes a metal layer and a resin layer, and the non-wiring portion includes a resin layer, and the circuit board includes the resin layer at 23 ° C. When the relative dielectric constant of the resin layer at a frequency of 10 GHz is 2 to 3, the maximum thickness of the wiring part is A (μm), and the minimum thickness of the non-wiring part is B (μm). , (A−B) /B≦0.1. [Selection] Figure 1 |