The present invention relates to a circuit substrate having a first conductive layer. The first conductive layer includes at least one power/ground plane. The power/ground plane includes at least one plane edge and plurality of grid lines. Each grid line has a width. The grid lines intersect each other to define a plurality of first grid holes, wherein the distance between the first grid hole that is closest to the plane edge and the plane edge is 1.5 times the width. Thus, the influence on the resistance of power signal and ground signal caused by the first grid holes is reduced, power integrity is improved, and heat generation is reduced.