The durability of new rigid disks by molded plastic substrates (abstract)

Abstract

Media that have discrete data tracks and servo pits for rigid disk systems have been developed.1 Discrete data tracks and servo pits are embossed on plastic substrates by a stamping technique similar to that used in optical disk technology. The outer diameter of the substrates is 65 mm, and the thickness is 1.2 mm. To enhance the durability of contact-start-stop (CSS) environment and reduce glide height, we have developed a method of texturing the surface with a fine dispersion of SiO2 particles, whose diameters are between 10 and 40 nm, by dipping. Thin film layers are then sputtered on the substrates, and the shapes of SiO2 particles are reflected in the surface profile of the thin film layers. The initial friction coefficient (μi) is 0.46, and the friction coefficient after 50 000 CSS events is 0.56 for CSS tests on molded plastic substrates at a radius of 28 mm. In addition, glide height depends on surface roughness of the disks. Surface roughness of a glass template used on stampers is carried over to the molded plastic substrates. Therefore the arithmetic average (Ra) of the molded plastic substrates with SiO2 particles is 1.5 nm. The peak-to-valley height (PV) is 20 nm, reducing the glide height to less than 65 nm. Simultaneously, with these media, a slider flying height of 0.1 μm has been achieved. Therefore, the media satisfy parameters of CSS environment, glide height, and flying height for rigid disks.