JPS62120620A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the S/N and the stability with time by providing a magnetic recording layer formed by disposing a carbon film on a high-polymer film and diffusing Bi or Sb at the grain boundary of the surface of pulverized Co or Co-Ni particles. CONSTITUTION:This magnetic recording medium is provided with the magnetic recording layer 3 formed by disposing the carbon film 2 of the high-polymer film 1 and diffusing Bi or Sb at the grain boundary of the surface of the pulverized Co or Co-Ni particles. The pulverized Co or Co-Ni particles are made uniform and a grain boundary diffusion layer is made thin by such constitution and therefore, the magnetic sepn. among the particles is improved and noise is considerably improved. The remaining of the excess Bi or Sb is obviated. The stability with time is improved as well.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to magnetic recording media such as magnetic tapes and magnetic disks that can be used for high-density magnetic recording.

Conventional technology In recent years, C has been used as a magnetic recording medium suitable for high density magnetic recording.
For perpendicular magnetic recording represented by o-0r perpendicular magnetization film, Go
-Ni70 Research into the practical application of so-called metal thin film type magnetic recording media for longitudinal magnetic recording, typified by in-plane magnetized films, is active.

Regardless of the type, (1) the saturation magnetic flux density is large, (2) the squareness in the direction of the axis of easy magnetization is good ((2
) A basic requirement for a ferromagnetic metal thin film is that it has a large retaining force, and based on that premise, a material composition that has low noise, good durability, and is resistant to rust is required.At present, these are relatively balanced. Go-Ni-0 film is known to be highly satisfactory, but the saturation magnetic flux density is 3.
Improvements have been made since it does not have much noise, ranging from 000 Gauss to 6000 Gauss.

As a magnetic recording layer, a ferromagnetic metal thin film without perpendicular magnetization is said to be promising for the time being, and many proposals have been made. [For example, foreign journals, IEEKTr&nsI!Lction
on Magnetics) 'io l, MA
See G-21゜PP, 217-1220 (1985)]
Among them, a magnetic recording layer obtained by depositing a CO alloy on top and bottom of Bi and then heat-treating it to diffuse it near the surface layer of the B11Co alloy fine particles satisfies the above basic requirements and also It is also attracting attention from the aspect of mass production, which can increase vapor deposition efficiency regardless of the vapor deposition method.

Problems to be Solved by the Invention However, with the above-mentioned configuration, the playback sensitivity during short wavelength recording can be improved, but the noise is also large, and the signal-to-noise ratio is large enough to achieve high density digital recording and analog recording. There were problems in that it was not possible to obtain a ratio (hereinafter referred to as S/N) and in stability against changes over time. The present invention was made in view of the above circumstances, and provides a magnetic recording medium with improved S/N ratio and improved stability over time.

Means for Solving the Problems In order to solve the above problems, the magnetic recording medium of the present invention includes a carbon film disposed on a polymer film, and Co or Co-N.
It is entirely equipped with a polishing recording layer in which Bi or sb is diffused at the grain boundaries on the surface of i-fine particles.

Effect The magnetic recording medium of the present invention has the above-described configuration, so that GO or Go-Ni fine particles can be made uniform, the grain boundary diffusion layer can be thinned, so the saturation magnetization can be increased, and the grain boundary diffusion layer can be made uniform. This results in improved magnetic separation between particles, greatly improved noise, and improved stability over time since no excess i or sb remains.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to all the drawings.

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to a first embodiment of the present invention. In FIG. 1, 1 is a polyamide film with a thickness of 10/Im, 2 is a carbon film with a thickness of 360 mm formed by high-frequency sputtering, and 3 is Go-Ni (Ni) obtained by oblique evaporation. 20wt%) thin film [film thickness 150o
These fine particles have a structure having a diffusion layer 4 of B or sb on the surface.

Reference numeral 5 designates the core inside the microparticle, which is schematically shown, and is a portion responsible for ferromagnetism.

The following Table 1 shows main manufacturing conditions of the present invention and manufacturing conditions without a carbon film as a comparative example.

For the above Examples M to D, and the comparative example F, 8 g
Although all magnetic tapes with a width of 0.8
The results of a relative comparison of S/N when recording in μm are summarized in Table 2 below.

(hereinafter referred to as gold and white) As described above, according to the manufacturing method of the present invention, B1゜sb1
When formed on a carbon film, even 100 people can form a uniform continuous film, which allows for uniform grain boundary diffusion during subsequent heat treatment, improving magnetic properties and improving S/N. The stability over time as represented by heating storage at 60'C is also good, whereas in E and F, direct film formation on 200A polyamide does not form a continuous film, but has an island structure, so grain boundaries Contains Go-Ni fine particles that cannot diffuse sufficiently, resulting in poor magnetic separation and poor S/N magnetic properties.
Too bad.

For example, if the conventional method is to form St), Bi (i-460 people,
Even if the uniformity of the grain boundary diffusion layer is improved, Sb, Bi
The superiority of the present invention is clear because a residual amount is generated, the change over time becomes large, and the corrosion resistance deteriorates.

FIG. 2 is an enlarged sectional view of a magnetic recording medium according to a second embodiment of the present invention.

In Figure 2, 6 is a polyimide film with a thickness of 26 μm, and 7
8 is a carbon film with a thickness of 400 μm formed by flash vapor deposition, 8 is CO fine particles with a grain boundary diffusion layer (SB or Bi (which can be used as an i-diffusion element) 9, and the film thickness is 700 A. It is formed by a sputtering method.

In order to form a grain boundary diffusion layer, sb is first deposited on the carbon film.
110 people each formed a Bi layer and a Bi layer by electron beam evaporation, and then coated them with a co-coat r+N, (mu r:N2=1=2).
High frequency (13,56MH
2. Maximum output 3KW) Thin film made by sputtering method and heated to 230℃
, heat treatment was carried out for 37 minutes in a murky atmosphere.

The magnetic recording layer thus obtained has a coercive force of 500 (Oe)
, with a residual magnetic flux density of 1 aooo (fly), in the form of a disk, with an amorphous (Go-Zr-Nb system) alloy ring type magnetic head with a gap length of 0.25 μm and a track width of 12 μm, recording and reproduction of 0.6 μm, S/N
'i Measured with the same head.

The S/N O (dB) was measured without a carbon film, that is, directly on the polyimide with 470A Bi electron beam evaporation, and then a Go film of 1700 was formed under the same conditions, and at 250°C.
This is the value of a magnetic disk obtained by heat treatment in an uneven atmosphere for a long time.

The product of the present invention and the comparative example were compared in initial value and S/N when left in an environment at 60°C (see Table 3). The product of this invention is Bi, S
All of the b values showed the same value.

(hereinafter referred to as "Kinpaku") As described above, it can be seen that the product of the present invention has a good S/N ratio and high stability.

In the first and second embodiments, the polymer films are made of polyamide and polyimide, respectively, but they may also be made of polyether sulfone, polyphenylene sulfide, polyethylene naphthalate, polyethylene terephthalate, etc.

Effects of the Invention As described above, according to the present invention, by using a ring-type magnetic head, high-density magnetic recording and reproduction can be performed with good S/N in both tape-shaped and disk-shaped formats, and Excellent effects such as extremely good stability can be obtained.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to a first embodiment of the invention, and FIG. 2 is an enlarged sectional view of a magnetic recording medium according to a second embodiment of the invention. 1.6...Polymer film, 2,7...
- Carbon film, 4, 9... Grain boundary diffusion layer.

Claims (1)

[Claims] A carbon film is placed on a polymer film, and Co or Co-
A magnetic recording medium characterized in that a magnetic recording layer in which Bi or Sb is diffused at grain boundaries is arranged on the surface of Ni fine particles.