HERSTELLUNGSVERFAHREN FÜR EIN PLATTENMEDIUMSUBSTRAT

摘要

A substrate for disc medium of resin used for disc, e.g., magnetic disc adapted so that recording or reproduction is carried out by the floating head. This substrate is adapted so that projection having height of 50 nm or more is not formed on the surface where the floating head scans of this substrate. In molding of this substrate, the substrate is molded by conducting a control such that the number of particles having particle diameter of 0.5 mu m or more within the molded body is 10000/g or less. As molding, e.g., injection molding is used. As resin, e.g., thermoplastic norbornene resin is used. Uneven portions corresponding to recording tracks may be provided on the substrate.