A circuit board and a manufacturing method therefor. The circuit board includes a substrate and a plurality of traces arranged at intervals on the substrate. Each trace includes a seed layer located on one surface of the substrate, a first copper layer located on the surface of the seed layer away from the substrate, and a second copper layer plated on one surface of the substrate. The second copper layer covers the seed layer and the first copper layer. The ratio of the thickness of each trace to the space between any two adjacent traces is greater than 1. The thickness of the second copper layer in the thickness direction of the substrate is greater than the thickness of the second copper layer in a direction perpendicular to the thickness direction of the substrate.