Optical disk, substrate of the same, and mold for forming the substrate

摘要

A clamp plate retaining surface, a handling surface positioned outside the outer circumference of the clamp plate retaining surface, and an information surface outside the outer circumference of the handling surface are provided in a substrate. The handling surface is formed to be a slope with its outer circumferential side being inclined downward with respect to the information surface. The resin forming the inner circumferential side end of the handling surface is melted and deformed to form a projection part, so that a clamp plate can be retained. Since the top part of the slope is deformed, a large projection part can be formed. As a result, a thin small-diameter optical disk and substrate can be obtained.