JP2543123B2 - Method of manufacturing magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high density magnetic recording medium.

2. Description of the Related Art In general, a magnetic recording medium prepared by coating a ferromagnetic metal or alloy on a polymer film by vacuum vapor deposition, sputtering, or by binding magnetic powder on a substrate together with a binder component is a recording medium. The magnetic layer is liable to wear during reproduction because it is in strong contact with the magnetic head. In particular, the ferromagnetic metal thin film layer formed by vacuum deposition has characteristics suitable for high-density recording, but it does not wear out due to high-speed sliding contact with the magnetic head. It had the drawback of being easily damaged and poor in durability. For this reason, efforts have conventionally been made to improve wear resistance by providing various protective film layers on the magnetic layer. For example, a film containing carbon as a main component may be provided using a hydrocarbon compound (see Methods such as providing a diamond-like hard carbon film (JP-A-59-127232) have been proposed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in order to secure a sufficient C / N in a shorter wavelength region in the magnetic recording medium having the above-described structure, it is necessary to thin the diamond-shaped hard carbon film. On the other hand, if the carbon film is too thin, the durability becomes insufficient.

In view of these problems, it is an object of the present invention to provide a method of manufacturing a magnetic recording medium that can provide sufficient durability with a film thickness that cannot be obtained by conventional manufacturing methods.

Means for Solving the Problems The method for manufacturing a magnetic recording medium of the present invention for solving the above-mentioned problems, after forming a diamond-like hard carbon thin film on a ferromagnetic metal thin film, sputter etching this carbon thin film, A lubricant layer is formed on top of it.

The diamond-like hard carbon thin film is formed once by the above-mentioned manufacturing method and then processed into a predetermined film thickness by sputter etching, so a thin film with no defects can be formed, so sufficient durability and C / N are well balanced. Obtainable.

Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings. The drawing is an enlarged cross-sectional view of a magnetic recording medium obtained by a manufacturing method according to an embodiment of the present invention. In the figure, 1 is a polymer film such as polyethylene terephthalate, polyphenylene sulfide, polyether sulfone, and polyamide imide. If necessary, a film with an undercoat layer on which fine projections such as fine particles or water-soluble polymer projections are arranged. You may use. 2 is Co-Ni, Co-Cr, Co-Ti, C
A ferromagnetic metal thin film such as o-Mo, Co-O, or Co-Ni-O can be formed by an electron beam evaporation method, an ion plating method, a sputtering method, or the like. Next, a diamond-like hard carbon film 3 is formed to a thickness of 300 Å to 500 Å by using plasma of hydrocarbon gas or sputtering targeting graphite, and then Ar, Ar + O ₂ etc. Sputter etching is performed by using the discharge gas of 2), which is a preferable thickness for minimizing the spacing loss and ensuring high output in high density recording.
The diamond-shaped hard carbon film 3 is thinly processed again in the range of 50Å to 150Å. After that, fatty acids, fatty acid amides, perfluorocarboxylic acids,
A lubricant layer 4 such as perfluoropolyether is arranged and processed into a tape or disk shape to obtain a magnetic recording medium.

Hereinafter, examples will be described more specifically in comparison with comparative examples. A polyethylene terephthalate film with a thickness of 10 μm was placed along a cylindrical can with a diameter of 1 m, and 6 × 10 ⁻⁵ (Torr) oxygen was incident on this film at a minimum incident angle of 42 °
Co + Ni (Ni: 20wt%) was deposited by 0.11μm electron beam, then transferred to another vacuum device, and graphite was placed in series as four targets, and 13.56 (M
Hz), 1 (KW) high frequency power, Ar + H ₂ = 0.04 (To
rr), Ar: H ₂ = 1: 3 discharge gas is used to form a diamond-like hard carbon film of 380 Å by high frequency sputtering. Next, six graphite electrodes were arranged in series, and a voltage of +450 (V) was applied to this graphite electrode to
The hard carbon film was sputter-etched under the conditions of r + O ₂ = 0.02 (Torr) and Ar: O ₂ = 1: 2, and a part of the hard carbon film was reactive sputter-etched to achieve high-speed etching as CO ₂ . The hard carbon film was adjusted to 110 Å by sputter etching. The hard carbon film thus obtained partially formed dome-shaped fine irregularities. Methyl caprate was vapor-deposited on the upper layer by a vacuum vapor deposition method at a rate of 40Å and then processed into a magnetic tape having a width of 8 mm. On the other hand, in the comparative example, by operating only the high frequency sputtering part, a graphite target of 13.56
(MHz), 600 (W) was charged, and a diamond-like hard carbon film was formed under the same conditions as in Example except that 120Å was formed. Both tapes were compared and evaluated by an 8 mm video.

At 40 ° C. and 80% RH, the example showed that the luminance signal output was −0.3 to −0.4 (dB) after running 100 times, while the comparative example was running 28 times, resulting in a decrease in runnability. At that point the output is -1.
It was 3 to -1.6 (dB). With respect to the tape that was left for 3 weeks by repeating the dew condensation cycle of 40 ° C. and 20 ° C. every 4 hours, the output of the comparative example was −0.6 to −4.9 (in comparison with the initial value and the output was not changed. It was unstable with dB).

Effects of the Invention As described above, according to the manufacturing method of the present invention, there is an excellent effect that a high-density magnetic recording medium having excellent storage characteristics and durability can be manufactured.

[Brief description of drawings]

The figure is an enlarged cross-sectional view of a magnetic recording medium obtained by the method of the present invention. 3 ... Diamond-like hard carbon film, 4 ... Lubricant layer.

Claims (1)

(57) [Claims] 1. A diamond-like hard carbon thin film is formed on a ferromagnetic metal thin film, and the hard carbon thin film is sputter-etched to a predetermined thickness to form a lubricant layer on the hard carbon thin film. Manufacturing method of magnetic recording medium.