JPH01105326A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To assure durability and to decrease spacing loss by disposing a reaction tube having an aperture in proximity to a thin ferromagnetic metallic film on a moving substrate and forming a carbon film by glow discharge. CONSTITUTION:The substrate for treatment formed with the thin ferromagnetic metallic film directly or via a fine particle coated layer of Al2O3, etc., on a high-polymer film is mounted to an unwinding shaft 2 and a take-up shaft 3. After the inside of a vacuum vessel is evacuated, gaseous methane is introduced into the vessel and high frequencies are impressed to a high-frequency coil 12. On the other hand, a positive potential is impressed by a DC power supply 8 to an accelerating electrode 6 for a graphite electrode 5. A thin hard carbon film is formed on the thin ferromagnetic film on the substrate 1 under movement by the glow discharge between the electrodes 5 and 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a magnetic recording medium having a magnetic recording layer made of a ferromagnetic metal thin film suitable for high-density magnetic recording.

Conventional technology The so-called 2-base evaporation tape, in which Go-Ni is obliquely evaporated by electron beam evaporation directly or through an underlayer on a polymer film, improves electromagnetic conversion characteristics and durability by introducing oxygen gas during evaporation. , aiming to improve corrosion resistance [for example, IEE Transactions on Magnetics (I[]ETransactions o
n Ma (netics) volIMAG-20
, No-5, P, P, 824-826 (1984)]. One way to further improve durability is to make the magnetic recording layer finely uneven [IEE Transactions on Magnetics vol:, M
AG-21, P, P, 1524-1526 (1985)
). In addition, many combinations of protective films and lubricants are being considered, and the protective effects of amorphous carbon thin films, including diamond-like hard carbon thin films, are attracting attention [
Institute of Electronics and Communication Engineers, Magnetic Recording Study Group materials, MRss-se (
1986), JP-A-61-142525, JP-A-61-142525
1-126627, etc.].

Problems to be Solved by the Invention However, when a hard carbon film is formed by the conventional method, Go-Or, which is expected to have high-density recording performance, including the case where the ferromagnetic metal thin film is a partially oxidized film.
, Go-0r-Nl), etc., when trying to increase the protective effect, the film thickness becomes thicker, so spacing loss at short wavelengths becomes a problem, and improvements have been desired.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for manufacturing a magnetic recording medium with small spacing loss while ensuring durability.

Means for Solving the Problems In order to solve the above problems, the method for manufacturing a magnetic recording medium of the present invention provides a method for producing a magnetic recording medium that has an opening in close proximity to a ferromagnetic metal thin film on a moving substrate such as a polymer film. A reaction tube is placed, a graphite electrode is placed near the opening, and an accelerating electrode is placed near the hydrocarbon gas inlet, and glow discharge is induced while the accelerating electrode is held at a positive potential with respect to the graphite electrode to form a carbon film. It is designed to form a .

Effect: According to the above production method, hydrocarbon-based discharge gas is decomposed into carbon and hydrogen by glow discharge, and the - portion also exists as carbon ions and hydrogen ions. These ions have a sputtering action on the graphite electrode, and the carbon obtained by the sputtering action is generated close to the ferromagnetic metal thin film, so it is deposited on the thin film without losing energy. As a result, a carbon film with good quality and few defects is obtained, so that even if the film thickness becomes thinner, a carbon film with sufficient protective effect can be provided.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. The figure is a configuration diagram of main parts of a thin film forming apparatus used to carry out the manufacturing method of the present invention.

In the figure, 1 is a treated substrate, and Go-Ni, C
A ferromagnetic metal thin film such as o-Ni-0 or Go-Cr is formed by electron beam evaporation, high frequency sputtering, or the like. 2 is an unwinding shaft, 3 is a winding shaft, and 4 is a reaction tube, the opening of which is provided in close proximity to and opposite to the thin film of ferromagnetic metal 6A, and the open end of the opening is provided inside the opening. A ring-shaped graphite electrode 5 is arranged along the circumference, creating a mesh-like accelerating electric current! 6 is arranged on the gas introduction part 7 side. Mesh-like accelerating electrode 6 and graphite electrode 5
A DC power supply 8 is connected between the graphite electrodes 5 and
The mesh-like acceleration electrode 6 is kept at a positive potential. 9 is a vacuum chamber, 1o is a vacuum exhaust system, 11 is a hydrocarbon gas introduction control valve, and 12 is a high frequency coil.

A magnetic recording medium manufactured by the manufacturing method of the present invention using the apparatus shown in the figure will be described below in comparison with a comparative example.

1 q/p m of 1203 particles with a diameter of 100 were placed on polyethylene terephthalate with a thickness of 10 μm in advance.
Thereafter, this film was placed along a cylindrical can with a diameter of 1 m, and Go-Ni (Co: 80 wt%) was electron beam evaporated at a minimum incident angle of 44 degrees and an oxygen partial pressure of 5 x 1o-5 Torr to form a film with a thickness of 0.1 μm. Prepare a processing substrate with a Co-Ni-0 film placed on it, and set the vacuum chamber to 10'To
After exhausting to rr, methane 6 hedge gas was introduced, and a high frequency of 13.56 MHz was applied to the high frequency coil to induce a high frequency glow discharge at 0.05 TOrr, and 850 m
A hard carbon thin film with a thickness of 100 A was formed while V was applied. 5OA of perfluorooctanoic acid was formed thereon by vacuum evaporation to form a magnetic tape with a width of 8 mm. On the other hand, as a comparative example, with the graphite electrode removed, a positive voltage of 850 V was applied to the accelerating electrode, a hard carbon thin film of 20 OA was formed under the same glow discharge conditions, and a hard carbon thin film of 20 OA was formed on it by vacuum evaporation method. perfluorooctanoic acid to form 5OA, 8
It was made into a millimeter-wide magnetic tape.

An 8 mm video deck was modified for both tapes, the carrier frequency was increased from 5 μm2 to 7 MHz, and the C/N was compared.

The initial C/N of the example was 2.1 dB better than that of the comparative example, and the C/N of the 300th playback after repeated running at 40'05% RH was within 1 dB of the example. However, the comparative example had a decrease of 1.5 dBc/N.

The above-mentioned tendency of characteristic deterioration is due to the G o -Or perpendicular magnetization 7
In the case of a H-7 film, the thickness is further increased, and if the method of the example is used, the protective effect can be said to be at a practical level at 150 µm, but the required thickness is 350 µm in the comparative example, which is a large thickness. This is due to the increased spacing loss. In this example, the graphite electrode is ring-shaped, but a plurality of electrodes may be arranged around the inner periphery of the reaction tube.

Effects of the Invention As described above, the present invention has excellent effects in that a magnetic recording medium with low spacing loss and good durability suitable for short wavelength recording can be manufactured.

[Brief explanation of the drawing]

The figure is a configuration diagram of main parts of a thin film forming apparatus used to carry out the present invention. 1... Processing substrate, 4... Reaction tube, 5.
...graphite electrode, 6...acceleration electrode. Name of agent: Patent attorney Toshio Nakao and one other person (-
-Founding a place 4-and-shokan 6-111 Delaphite capture r3 curse 6゛---η0 eagle t'J over 7

Claims (1)

[Claims] A reaction tube is provided with an output side opening closely facing a ferromagnetic metal thin film on a moving substrate, and the reaction tube has a graphite electrode disposed at the inner end of the opening and a hydrocarbon gas inlet and an accelerating electrode arranged therein, and a glow discharge is induced while the accelerating electrode is held at a positive potential with respect to the graphite electrode, and a carbon film is formed on the ferromagnetic metal thin film. A method for manufacturing a magnetic recording medium.