Disc molding die

Abstract

A disc molding die includes a stationary-side mirror block disposed on a stationary die, a movable-side mirror block disposed on a movable die and facing the stationary-side mirror block so as to define a cavity in combination with the stationary-side mirror block, and a cavity ring disposed on the radially outer side of one of the stationary-side mirror block and the movable-side mirror block so as to define the outer circumferential edge of each disc substrate. The portion of the cavity ring facing the cavity is roughened. When resin is charged into a cavity, very small spaces are formed between the resin and the inner circumferential surface of the cavity ring, due to the roughened portion of the cavity ring facing the cavity. Therefore, the release resistance during die opening or releasing can be decreased. As a result, it is possible to solve the conventional problem in which the disc substrate deforms, causing the angle of warp to vary at circumferential positions and increasing the amount of surface deflection. Therefore, the quality of the disc substrate can be increased. Further, since the release operation can be performed before a molded disc substrate sufficiently shrinks, tact time can be shortened.