JPH0371418A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium suitable for high-density recording by forming an oxide film as a protective layer by sputtering, specifying the surface roughness of the magnetic recording medium by the average roughness on the center line and the maximum roughness height, and specifying the relative load length of the relative load curve. CONSTITUTION:An oxide film is formed as the protective layer by sputtering and the surface roughness of the magnetic recording medium is specified so that the average roughness Ra on the center line is between >=15Angstrom and <=40Angstrom and the maximum roughness height Rmax <=1,000Angstrom . The difference of cutting depth DELTACv(10%-1%) between values at 10% loading length and at 1% loading length in the relative loading curve is specified to between >=50Angstrom and <=150Angstrom . The obtd. medium has excellent durability and lubricating property for CSS operation even against a hard slider magnetic head and has good quality of roughness to enable low-height floating of a magnetic head. Thereby, the medium can be used for high-density recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium used in a fixed magnetic disk device.

[Conventional technology]

The manufacturing methods for magnetic recording media (hereinafter also simply referred to as media) range from coating methods in which the magnetic layer is a coating film in which γ-pe20s magnetic particles are dispersed in a resin binder to continuous thin films of ferromagnetic alloys such as CO-based alloys. There has been a shift to plating methods, and then to sputtering methods, which use carbon as a magnetic layer. This is due to the increasing capacity and miniaturization of fixed magnetic disk drives, which are the mainstream peripheral storage devices for information processing systems, and there has been an increasing demand for higher recording densities in the media installed in these drives in recent years. Thin-film media whose magnetic layer is a continuous thin film of 9 ferromagnetic alloy manufactured by sputtering can have high coercive force, and it also makes it possible to shorten the distance between the magnetic head and the magnetic layer, resulting in high recording density. This is because it can meet the needs of the public.

In a medium manufactured by the above-mentioned sputtering method, it is necessary to protect the magnetic layer, which is a thin alloy film, from corrosion. Furthermore, fixed magnetic disk drives generally employ the C8S method, and it is necessary to protect the medium surface from wear caused by the C5S of the magnetic head, an increase in the coefficient of friction, or adsorption of the magnetic head. For this reason, in thin film media, it is necessary to provide a protective layer on the magnetic layer made of a material that is chemically stable, has good lubricity, and can form a high-quality film with high wear resistance.

Conventionally, a carbon (C) protective layer is provided within the film;
Furthermore, in order to improve the lubrication performance, a liquid lubricant is further applied thereon to provide a liquid lubricant layer. It has also been practiced to form an S]02 protective layer on the magnetic layer by a spin code method, and to provide a liquid lubricant layer thereon.

[Problem to be solved by the invention]

Materials for magnetic heads are currently becoming harder. The C protective layer added with the C protective layer or the liquid lubricant layer is Mn-
It is effective for magnetic heads of sliders made of 2n ferrite, but it is effective for magnetic heads of sliders made of 2n ferrite, but
*It is not suitable as a protective layer for the magnetic head of a slider made of a hard material such as C) because it is subject to severe wear.
Moreover, the problem becomes more serious as the film thickness is made thinner with the aim of achieving higher density recording.

On the other hand, S+ by spin code method with added liquid lubricant layer
Although the 02 protective layer has sufficient abrasion resistance even for hard slider magnetic heads, it has the disadvantage that the quality of the surface protrusions is not good. If the quality of the protrusions on the surface of the protective layer, that is, on the medium surface is poor, there will be a problem that the magnetic head will come into contact with the protrusions on the medium surface more frequently when the magnetic head is flying, which may lead to a head crash.

The smaller the flying height of the magnetic head is for high-density recording, the more likely the above-mentioned phenomenon will occur, making the SiO□ protective layer formed by the spin code method with a liquid lubricant layer added unsuitable.

In addition, in order for the magnetic head to repeat a good CSS method on the medium surface, it is necessary that the medium surface has good lubrication performance and that the magnetic head does not attract. Although the surface must be uniformly roughened, it is difficult to form the 5102 protective layer with appropriately controlled surface roughness using the spin coding method.

Moreover, as the flying height of the magnetic head is reduced, the surface roughness must be controlled with higher precision, which becomes even more difficult.

The problem to be solved by the present invention is to solve the above-mentioned problems and provide a magnetic recording medium equipped with a protective layer that can suitably cope with high-density recording.

[Means to solve the problem]

According to the present invention, the above-mentioned problem can be solved by using a magnetic material that includes a ferromagnetic alloy thin film magnetic layer formed by sputtering on a non-magnetic substrate, and a protective layer and a liquid lubricant layer further formed on this magnetic layer. In the recording medium, the protective layer is an oxide film formed by a sputtering method, and the surface roughness of the magnetic recording medium is such that the center line average roughness Ra is within the range of 15 Å or more and 40 Å, and the maximum height is Rmax is 1000A or less, and the value △Cv (10% - 1%) of the relative load curve, which is the cutting depth at 10% relative load length minus the cutting depth at 1% relative load length, is 50A or more15
This problem can be solved by using a magnetic recording medium with a thickness of 0 Å or less.

[Effect]

By using oxide as the material for the protective layer of the medium,
A protective layer that is hard and has excellent wear resistance can be formed, resulting in a medium that has sufficient wear resistance even for magnetic heads with hard sliders made of ceramic or the like. Moreover, since this layer is formed as a thin film by sputtering, its surface has a surface roughness corresponding to that of the nonmagnetic substrate, similar to the surface of the magnetic layer.

Therefore, by processing the substrate surface into a specific and appropriately uniformly roughened surface shape, the protective layer surface will have a correspondingly uniformly roughened surface shape with an appropriate roughness, and microprotrusions will also be eliminated. With less amount, the quality of the protrusions is also good.

There are various ways to specify surface roughness, and the following evaluation quantities are effective for the media surface, but each has important meanings while being intertwined, so surface roughness cannot be determined with only one evaluation quantity. It seems impossible to specify.

Ra: Specified in JIS as "center line average roughness", a general amount that indicates the average roughness of the surface Rmax: Specified as "maximum height" in JIS, the surface roughness Quantity related to the protrusion quality ΔCv (10%-1%): The amount obtained by subtracting the cutting depth at a relative load length of 1% from the cutting depth at a relative load length of 10% in the relative load curve. Among these, the amount related to the protrusion quality is tm in the sputtering method, and these Ra.

A protective layer of an oxide film with a surface roughness with an appropriately specified amount of Rmax and ΔCv (10%-1%) can cope with the reduction of the flying height of the magnetic head, and can also be used for liquid lubrication provided on it. Coupled with the action of the layer, the medium surface is exposed to the C3S of the magnetic head.
This results in a medium that can be effectively protected from an increase in the coefficient of friction due to abrasion 2 or from being attracted by a magnetic head, and can suitably accommodate high-density recording.

〔Example〕

The surface of a 3.5-inch diameter JV alloy substrate plated with N1-P was smoothed by polishing, and then the substrate surface was roughened using a polishing tape. By changing the polishing conditions at this time, substrates with various surface roughnesses were produced.

Cr, Co-N
Each layer of i-Cr alloy and Sin was successively formed in this order. The sputtering conditions are shown below.

Ar gas pressure 10+nTorr substrate heating temperature
220° C. Substrate heating time: 7 minutes Next, a fluorocarbon-based liquid lubricant was applied on the 5103 layer by a dipping method to form a liquid lubricant layer with a thickness of 15 mm to form a medium.

The lubrication performance and protrusion quality of the medium surface were evaluated for the medium thus produced.

The lubrication performance was evaluated by the friction coefficient when a sliding friction and wear test, which is a type of accelerated test, was conducted in which the medium was rotated at a low speed that did not allow the magnetic head to fly and the magnetic head was slid on the medium. A hard slider magnetic head made of AjhOs/Tic was used as the magnetic head.

Further, the quality of the protrusions was evaluated by counting the number of protrusions using GHT (glide hide test). The flying height of the magnetic head was 0.15 μm.

The evaluation results are shown in Table 1 together with the surface roughness of each medium.

/ / / / / Table l From Table 1, Ra is 20 to 35A, Rcnax
is 500 A ~ 700 people, ΔCv (10%-1%
) Surface roughness of 80 to 120 degrees is suitable, and Ra is 15 Å or more and 40 Å or less.

Rmax is 1000Å or less, ΔCv (10%-1%>
It can be seen that if the angle is 50 Å or more and 150 A or less, lubrication performance and protrusion quality with no practical problems can be obtained.

In the above embodiments, 5in2 was used as the material for the protective film, but the material is not limited to this, and other oxide materials such as Al2O are equally effective.

〔Effect of the invention〕

Claims (1)

[Claims] 1) A magnetic recording medium comprising a ferromagnetic alloy thin film magnetic layer formed by sputtering on a non-magnetic substrate, and a protective layer and a liquid lubricant layer further formed on this magnetic layer, in which the protective layer is formed by sputtering. an oxide film formed by a method, and
The surface roughness of the magnetic recording medium is such that the center line average roughness Ra is 15.
Within the range of Å or more and 40 Å, and the maximum height Rmax is 10
00 Å or less, and the relative load length of the relative load curve is 10%
The value ΔCv (10%-1
%) is within the range of 50 Å or more and 150 Å or less.