JPH0628107B2 - Magnetic disk - Google Patents

Description

The present invention relates to a magnetic recording hard disk, and more particularly to a protective film for a high density recording hard disk.

<Prior Art> In recent years, research has been conducted on high density in the field of magnetic recording, and since the perpendicular magnetic recording system was announced, the
Research and development activities are being carried out more and more aiming at the limit of magnetic recording regardless of the plane. Even in the field of hard disks, continuous thin film media having high coercive force and high residual magnetic flux density-plating and sputter film media-have been vigorously developed from the conventional coating type media. However,
In realizing "high density", it is important to reduce the air gap amount between the head and the medium while improving the magnetic characteristics of the medium. At present, a device in which the air gap amount of a hard disk is narrowed down to a value of about 0.25 μm has been put into practical use, but in order to achieve a significant improvement in linear recording density, the head / medium spacing /
It is necessary to reduce the loss, and therefore it is required to further reduce the air gap amount. In this respect, since the formation of the medium protective layer is directly related to the spacing loss, the thinning of the protective layer becomes a more important problem with the increase in density.

Conventionally, SiO ₂ coated with a lubricant is widely used as a surface protection layer against external impacts and abrasions in plated disks. However, regarding thinning of this, CSS
Since it is necessary to secure the strength for clearing (contact start / stop), a film thickness of about 300 Å is set as a practical limit, and there is a problem in putting it into practical use for future high density. Furthermore, there is a problem of adsorption of the head and medium by the lubricant, and it will be more difficult to control the amount of lubricant applied as the surface of the medium becomes smoother in the future. For this reason,
Recently, a film in which the material itself has lubricity has been studied as a material replacing SiO ₂ , and particularly good results have been reported for a graphite film.

<Objects of the Invention> The present invention has been made in consideration of the above-mentioned problems relating to the protective film, and provides a magnetic disk having a protective film having both durability and lubricity as compared with a graphite film, which is suitable for high density recording. The purpose is to provide.

<Example> Hereinafter, the protective film used in the present invention will be described in detail. First, the glassy carbon as the material of the protective layer will be described. Glassy carbon (product name: Grahard, manufactured by Kao Soap Co., Ltd.) has an amorphous structure in which crystallized graphite-like microcrystals are isotropically distributed to some extent. This material has a high hardness and a small coefficient of friction and is self-lubricating, and is characterized by being less likely to wear during surface contact under a small load. This is different from the lubrication action based on the exfoliation of the crystal plane, which is found in general lubricants using graphite. Already, this effect (self-lubrication, wear resistance)
In regards to the above, good running characteristics and durability have been reported to be used as a substrate material for a single magnetic pole head for perpendicular magnetic recording (Iwasaki, Nakamura, Kishine: 1985 IEICE General Conference 1-200). Using this glassy carbon material as a target and under the conditions shown in the table below, a protective film was formed on the magnetic medium using an RF bipolar sputtering device.

Each film obtained on the magnetic medium showed the same gloss as the target material, and it was found by film structure analysis by transmission electron microscopy that it had the same amorphous structure as the target material. Therefore, the characteristics of the film formed by the sputtering method using the above target are considered to exhibit the same characteristics as glassy carbon. Next, a low-speed running test was performed on each magnetic disk provided with a glass-like carbon sputtered film and a graphite sputtered film having a film thickness of 200 Å using a ferrite head. As a result, it was confirmed that the glass-like carbon sputtered film was superior to the increased head load because it was less likely to be damaged. From the above, it is recognized that the glassy carbon thin film is suitable as a protective film for a high-density recording hard disk and can be sufficiently used even when the thickness is 300 Å or less. Moreover, since it can be produced under a wide range of sputtering conditions, it also contributes to the improvement of productivity.

The attached drawings show 1 of the present invention using the above glassy carbon.
It is a schematic cross section block diagram of the magnetic disk which is an Example. A magnetic layer 2 having a high magnetic permeability made of Co-Cr, Ni-Fe or the like is layered on a hard disk substrate 1, and information is magnetically recorded on the magnetic layer 2. On the surface of the magnetic layer 2, a protective film 3 is formed by coating the above-mentioned glassy carbon having self-lubricating property into a thin film by a reactive sputtering method. The thickness of the protective film 3 is set to about 200Å. A head 4 is arranged so as to face the magnetic layer 2, and recorded information is reproduced via the head 4. This magnetic disk has good durability due to the abrasion resistance of the protective film 3, and enables high-density recorded information to be reproduced for a long time.

<Effects of the Invention> As described above in detail, according to the present invention, the protective film on the disk surface is excellent in lubricity, and the abrasion resistance is excellent and moderate, so that the head is not damaged and the recording medium is not damaged. The air gap of can be made extremely small,
It becomes possible to manufacture a magnetic disk compatible with high-density recording. In addition, it is possible to easily form a film by using glassy carbon as a target material, and usually a magnetic film is formed by sputtering. Therefore, it is possible to form a magnetic film and a protective film in succession, which is excellent in productivity. Due to the conductivity of carbon to some extent, static electricity is not generated, and dust is adsorbed or electrostatically destroyed (especially electrostatic breakdown of the head).
Can be prevented.

[Brief description of drawings]

The drawing is a schematic cross-sectional configuration diagram of a magnetic disk according to an embodiment of the present invention. 1 ... Disk substrate, 2 ... Magnetic layer, 3 ... Protective film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsushi Mukai 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor ▲ Mitsuhiko Yoshikawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka No. Sharp Co., Ltd. Examiner Toshiro Okamoto

Claims (1)

[Claims] 1. A magnetic disk comprising a self-lubricating glassy carbon thin film coated as a surface protective film.