WIRING SUBSTRATE, MULTI-PATTERN WIRING SUBSTRATE, AND MANUFACTURING METHOD THEREFOR

Provided are a wiring substrate having few burrs in the vicinity of a notch located on a side surface of a substrate main body, in which breakage of a conductor layer provided on the inner wall of the notch is suppressed; a multi-piece wiring substrate array for providing a plurality of the wiring substrates; and a method for reliably producing the multi-piece wiring substrate array. The wiring substrate 1a includes a substrate main body kp which is formed of a plurality of stacked ceramic layers S, which has a rectangular shape in plan view, which has a pair of opposite first and second main surfaces 3 and 2, and which has side surfaces 4 each being located between the paired main surfaces 3 and 2, and having a groove surface 6 located on a side toward the first main surface (back surface) 3 and a fracture surface 5 located between the groove surface 6 and the second main surface 2; and a notch 11 which has a concave shape in plan view, and which is provided on a side surface 4 only on a side toward the first main surface 3 so as to extend in a thickness direction of the side surface 4, wherein, in the side surface 4 having the notch 11, the boundary 7 between the groove surface 6 and the fracture surface 5 has first curved portions R1 on opposite sides of the notch 11, the first curved portions R1 being convex toward the first main surface 3 of the substrate main body kp in side view; and also has a second curved portion R2 on a second-main-surface side of the notch 11, the second curved portion R2 being convex toward the second main surface (front surface) 2 of the substrate main body kp in side view.