JPH0268712A - Thin film magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic recording medium. For details on the history,
The present invention relates to a thin film magnetic recording medium with improved durability.

[Prior Art] Conventionally, conventional magnetic recording media have a magnetic layer formed by coating a non-magnetic substrate with a magnetic medium mainly consisting of acicular magnetic powder and a polymeric binder. This is a coating-type magnetic recording medium.

Currently, there is a trend toward higher density magnetic recording and reproducing devices, and there is a demand for magnetic recording media with excellent short wavelength recording characteristics.

However, there are limits to the revision of short wavelength recording characteristics in cloth-type magnetic recording media. On the other hand, co + Co
C such as N 11 Co N iP + Co Cr
Metal thin film type magnetic recording media, in which a ferromagnetic material mainly composed of O is formed on a non-magnetic substrate by a so-called physical vapor deposition method such as vacuum evaporation, sputtering, or ion blating, have non-magnetic material in the magnetic layer. Since no binder is mixed in, a significantly high residual magnetic flux density can be obtained.
In addition, since the magnetic layer can be formed extremely thin, it has the advantage of high output and excellent short/1!! long response characteristics. Due to these characteristics, thin film magnetic recording media have recently become popular. is becoming the mainstream of magnetic media.

[Problems to be Solved by the Invention] However, there are still problems that must be solved in order to put such a continuous thin film magnetic recording medium into practical use.

Of particular importance among these issues is durability, i.e.
The problem is that the per-ear raw output decreases significantly due to long-time sliding of the magnetic head.

The first possible cause of such a reduction in reproduction output is the problem of wear of the magnetic head and recording medium due to sliding.

However, according to research by the present inventors, even if a protective lubricant layer is formed on the recording magnetic layer 1 of a magnetic recording medium to prevent wear between the magnetic recording medium and the magnetic nodal, , it was observed that the output was clearly lowered. Therefore, as a result of investigating the cause of this problem, we found that such low raw output is due to plastic deformation of the recording 64it'1 layer due to the sliding of the magnetic head, and an increase in svaning between the magnetic head and the recording magnetic layer. It has become clear that this is the case. A recording magnet like this? The deformation of the /12 layer is remarkable when the nonmagnetic substrate is made of poorly soft paulownia wood such as Aλ or a perforated polymer film, and as a result, the rI raw output is also significantly low.

Therefore, it is an object of the present invention to solve the problem of plastic deformation of the recording magnetic layer that the prior art has and thereby provide a thin film magnetic recording medium that outputs IIrIr force stably over a long period of time.

[Steps for Solving the Problem] As a means for achieving the above object, in the present invention, a material having a Mohs hardness of 5 or more is formed on a non-magnetic substrate by paper deposition. A thin film magnetic recording medium is provided, characterized in that it has a magnetic underlayer (II), and a recording magnetic layer is provided on the underlayer (l-) with or without a soft magnetic layer.

The material having a Mohs hardness of 5 or more is B or Si shell, or an alloy or compound thereof.

The thickness of the nonmagnetic underlayer formed on the nonmagnetic substrate-1- by paper deposition is preferably within the range of 500 Å to 5000 Å.

The recording magnetic layer is preferably a perpendicular magnetic anisotropic film made of Co alone or an alloy containing Co in the L form.

[Function] []; As described in item i, in the present invention, a base layer of 500 Å to 5000 Å is formed on a non-magnetic substrate by paper deposition, and is made of a material with a Mohs hardness of 5 or more. A recording magnetic layer is provided on the recording magnetic layer.

By adopting such a configuration, plastic deformation of the recording magnetic layer and the substrate due to the suppression of the magnetic head can be greatly alleviated, and a high reproduction output can be maintained even during long-time sliding.

In the present invention, the reason for using B or Si core, or an alloy or compound thereof as the material for forming the underlayer is as follows.

First, since these materials have very high hardness, they are highly effective in suppressing plastic deformation of the recording magnetic layer and the substrate even if the film thickness is less than t','j.

First, when these thin films are formed on a non-magnetic substrate l- by the Paper Devon, 47 method, they take on an amorphous structure, so the magnetic layer formed on the l-1- has a flat structure in terms of morphology and crystal structure. It is something that is not easily influenced.

In particular, when the magnetic layer is a Co-Cr alloy film, if the ground is amorphous, the Co-Cr will be well crystallographically oriented, resulting in an excellent C1['L' magnetized film. Become.

In addition, since the F layer mainly composed of 1-B + S t is morphologically unstructured, it is possible to suppress the formation of magnetic layer grains formed in the -H, and the magnetization j1 of the magnetic layer is can be made very small.

For the following reasons, providing a base layer with B and Si as a 1:1 body by the paper deposition method is the first step.
It is extremely effective in alleviating plastic deformation of the )^ plate and recording magnetic layer due to the sliding of the magnetic head, which impairs the properties of the magnetic layer formed on the magnetic layer.

The present inventors first provided a coating layer containing 3 non-magnetic fine powders with a Mohs hardness of 3 to 1 on a non-magnetic substrate,
Invented a magnetic recording medium with a thin magnetic layer on the magnetic layer.
An application was filed (Japanese Patent Application No. 62-057393-S). This invention also provides the effect of preventing plastic deformation of the magnetic layer and the magnetic substrate. However, when a magnetic layer is formed on the coated upper layer 1- by a paper deposition method, gas is generated from the binder and other substances contained in the upper layer, which deteriorates the characteristics of the magnetic layer. occurs.

The thickness of the base layer mainly composed of B and Si is 500 Å or more, which is sufficient to prevent plastic deformation of the substrate and recording magnetic layer due to the sliding of the magnetic head.
Preferably, the number is within 5,000 people. This is because when the thickness of the non-magnetic underlayer becomes 500 or less, the plastic deformation prevention effect becomes significantly weaker, and when it exceeds 5000, the
This is because a column structure begins to grow in the upper layer, and the grains of the magnetic layer formed on the top layer become coarser and the magnetic properties begin to deteriorate. In addition, in cases where flexibility is required, such as with floppy disks and tapes, the base layer thickness L should be 5.
000, the contact with the magnetic head deteriorates significantly and the 11r raw output envelope is also disturbed.

The recording magnetic layer is preferably composed of Co alone or a Co alloy. Co alloys include, for example, Co-Cr, C
o-Ni, Co-Ni-Cr.

These include Co-Fe, Go-Ti+Co-P, etc.

Other Co alloys can of course also be used. It is preferable that the 3rd degree lit of Co in the Co alloy is more than 50%.

If desired, a soft magnetic layer can be interposed between the upper layer and the recording magnetic layer. The types of soft magnetic layers that can be used or the specific materials used for forming such layers are well known to those skilled in the art. When a soft magnetic layer is interposed, the recorded magnetization of the perpendicular recording magnetic layer is stabilized, especially in the case of an eastward magnetic recording medium, and the recorded magnetization increases, resulting in a significant Flr raw output output of 1.
- becomes 1-iJ ability.

The thickness of the soft magnetic layer is within the range of 50 Å to 5,000 Å for boat fishing.

The nonmagnetic underlayer, soft magnetic layer, and magnetic recording layer can all be formed by a paper deposition method. “°
The paper deposition method is a method in which a substance or compound to be deposited is deposited on the gas as vapor or ionized vapor in a gas or 1° [empty space]. is vacuum evaporated.
, ion bracing left.

High-frequency ion brating method, ion e-cluster beam method, and ion beam 11 deposition.

There are sputtering methods, CVD methods, etc.

The non-magnetic underlayer, soft magnetic layer and recording magnetic layer are continuously formed by a
? I treatment is preferred. If you wear 74 pieces in a row, the neck tightness between each layer will be improved. The recording magnetic layer can be either obliquely deposited or perpendicularly deposited, but in the case of using a soft magnetic layer as described in 1r1, it is preferably a vertically oriented magnetic film.

The non-magnetic substrate used in the magnetic recording medium of the present invention is made of polyimide, polyethylene terephthalate, etc.
Films, glass, ceramics.

There are metal plates such as aluminum, anodized aluminum, and brass, and Si medium crystal plates whose surfaces are thermally oxidized.

This non-magnetic substrate may be provided with a hard polishing layer such as a nickel-phosphorous alloy layer or an alumite treatment layer for back surface polishing or texturing, if necessary.

In addition, as a magnetic recording medium, polyester film t.
, magnetic tapes and disks based on synthetic resin films such as polyimide film t, synthetic resin films,
It includes various forms of structures that come into sliding contact with a magnetic head, such as magnetic disks and magnetic drums whose bases are disks and drums made of aluminum plates, glass plates, etc.

[Example] Hereinafter, the present invention will be explained in detail with reference to examples.

Example 111 - A polyimide film substrate with a thickness of 40 II m,
A B upper layer with various thicknesses within the range of 0 to 1.0 μm was formed, and a Coat Crt q magnetic layer (0°25
μm) using the vacuum evaporation method at a substrate temperature of 230°C.
Q-order lamination was performed. 5. Recording medium formed in this way.
Punched into a 25 inch disc, gear Noah '140.
Recording cattle, l
l properties and their changes over time were measured. The results are summarized in Table 1 below. Table 1) 50 indicates the recording density at which the initial output decreases by 1', and is an indicator of high-density recording performance. Further, N80 indicates the number of times the magnetic head passes until the output decreases to 80% of the initial output.

If K±71 m (5,000 people) is exceeded, although a low output can be prevented, the medium rigidity is too high, causing deterioration in contact and disturbance of the envelope.

J1-21 Under the same conditions as in Example 1, the non-magnetic underlayer material was varied and the same evaluation was performed. The thickness of the non-magnetic underlayer is 0.2
C) 7jm. The measurement results are shown in Table 2 below.

, 2- As is clear from the above results, when the film thickness of the B underlayer is 0.
If it is less than 0.05/lln (500 people), the 11 raw output will drop in the early stages due to plastic deformation of the recording magnetic layer. In addition, the thickness of the B underlayer is 0.5.As is clear from the above results, the magnetic recording medium has a nonmagnetic underlayer formed from a B or Si-based material with a Mohs hardness of 5 or more. shows a stable reproduction output over a long period of time, but magnetic recording media with underlayers made of other materials drop the +IF output in a short period of time.

[Effects of the Invention] As explained below, in the present invention, the non-magnetic substrate l-
Then, a base layer made of B or Si-based material with a Mohs hardness of 5 or more is deposited with a thickness of 500 Å to 5
000 layers, and a recording magnetic layer is provided on the layer.

By adopting such a configuration, plastic deformation of the recording magnetic layer and the substrate due to the suppression of the magnetic head can be greatly alleviated, and a high reproduction output can be maintained even during long-time sliding.

B or Si-based materials with a Mohs hardness of 5 or higher have a very high hardness, so even if the deposited film is thin, it has a great effect in suppressing plastic deformation of the recording magnetic layer and the substrate.

In addition, when these thin films are formed on a non-magnetic substrate by the paper deposition method, they take on an amorphous structure, so the magnetic layer formed on that layer is less susceptible to the influence of the substrate in terms of morphology and crystal structure. be. In particular, the magnetic layer or Co
In the case of a -Cr alloy film, if the ground is amorphous, Co--Cr will be well crystallographically oriented, resulting in an excellent ITL direct magnetization film.

Historically, B or Si-based vapor deposition-base layer was morphologically; (l(
Because of this structure, it is possible to suppress the coarsening of the magnetic layer particles that are formed in the magnetic layer, thereby reducing the magnetization of the magnetic layer! The 11th place can be made very small.

Claims (4)

[Claims] (1) A nonmagnetic underlayer formed by vapor deposition of a material having a Mohs hardness of 5 or more on a nonmagnetic substrate, with or without a soft magnetic layer on the underlayer. , a thin film magnetic recording medium characterized by being provided with a recording magnetic layer. (2) The thin film magnetic recording medium according to claim 1, wherein the material having a Mohs hardness of 5 or more is B or Si alone, or an alloy or compound thereof. (3) The thin film magnetic recording medium according to claim 1, wherein the thickness of the nonmagnetic underlayer is within the range of 500 Å to 5000 Å. (4) The thin film magnetic recording medium according to claim 1, wherein the recording magnetic layer is a perpendicular magnetic anisotropic film made of Co alone or a Co alloy.