Interlayer connective structure of wiring board and method of manufacturing the same

An interlayer connective structure of a wiring board, suitable for being formed in the wiring board, wherein the wiring board comprises two traces and an insulation part between the traces, the insulation part has a through hole, and the interlayer connective structure located in the through hole is connected to the traces, wherein the interlayer connective structure comprises:

• a column, located in the through hole and having two opposite end faces;
• and
• a pair of protuberant parts, connected to the end faces and the traces respectively, and located at two ends of the through hole respectively, wherein each of the traces has an inner surface connected to the insulation part and an outer surface away from the insulation part, wherein the protuberant parts stick out from the outer surfaces of the traces respectively, each of the protuberant parts has a convex curved surface, and a distance between the convex curved surface and an axis of the through hole is less than a radius of the through hole;
• wherein each of the traces further has a long axis, and the through hole has a sidewall, wherein a wall thickness of each of the protuberant parts relative to the sidewall decreases gradually from the long axis and along the sidewall in a direction away from the long axis.