To lessen the fluctuation in the envelope of RF signals and to increase CN by raising mold temp. and heating cylinder temp. at the time of injection molding a polycarbonate substrate, increasing a mold clamping pressure and increasing a resin injection speed.
The mold temp. and heating cylinder temp. are increased, the resin injection speed is increased and further, the cooling time is prolonged at the time of injection molding of the polycarbonate substrate. A magneto- optical recording disk 20 having the structure shown in Fig. is formed on this polycarbonate substrate. Namely, this substrate consists of the structure obtd. by successively depositing SiN 7 as a protective layer at 1100, an amorphous perpendicularly magnetized film 8 of GdDyfeCo at 300, SiN 7 as the protective layer at 1100, the amorphous perpendicularly magnetized film 8 of GdDyfeCo at 300, SiN 7 as the protective layer at 500, AlTi10 as a reflection layer and commonly used thermal diffusion layer at 500 and an overcoating layer 11 consisting of a UV curing resin at 10μm on the substrate 6.
TANAKA SAYOKO
KUSUMOTO YASUYUKI
