JPS62125525A - Substrate for magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To enhance the strength of the titled substrate, to obtain a high- precision smooth surface in polishing, and to prevent the magnetization at a high temp. by forming an Al nitride layer on the surface layer of an Al base sheet. CONSTITUTION:In the substrate 13 for a recording medium, the Al nitride layer 7 is formed in the depth direction from the surface of the Al base sheet 1. Since the layer 7 has high hardness, the hardness of the substrate 13 is improved, and the high-precision smooth surface can be obtained in the polishing stage after the layer 7 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium substrate formed by surface-treating an aluminum base plate, and a method for manufacturing the same.

[Conventional technology]

FIG. 5 is a schematic partial cross-sectional view showing an example of a magnetic recording medium using a conventional substrate. As shown in the figure, in magnetic recording media such as plated magnetic disks, sputtered magnetic disks, and coated magnetic disks aimed at increasing density, aluminum-based (i.e., aluminum or aluminum alloy)
In order to improve the strength of the blank l and to obtain a highly precise smooth surface, a hard underlayer 2 is provided on the surface of the blank l to form a substrate 3 for a magnetic recording medium. .

In this case, the hard base layer 2 is generally formed by N1-P plating, alumite treatment (anodizing treatment), or the like.

Then, the surface of the substrate 3 is plated, sputtered,
A magnetic film 4 is formed by coating or the like, and usually a protective film 5 is applied on top of the magnetic film 4, and a lubricant 6 is applied thereon for the purpose of improving cheek feel.

[Problem that the invention seeks to solve]

Although it is necessary that the hard underlayer 2 is not magnetic, the hard underlayer 2 becomes magnetic at a temperature of about 250°C or higher when formed by N1-P plating, whereas when the magnetic film 4 is formed by sputtering, The hard base N2
may be heated to over 300°C, so N1
- In the case of the hard underlayer 2 made of P plating, there are restrictions on the method of forming the magnetic film 4 or the protective film 5.

On the other hand, when forming the hard base layer 2 by alumite treatment, if the thickness is increased, cracks may occur due to the difference in the coefficient of thermal expansion with the base plate 1, and if the hard base layer 2 is made thinner, the required hardness may not be obtained. be.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic recording medium substrate and a manufacturing method thereof that solve the above-mentioned problems.

[Means for solving problems]

The magnetic recording medium substrate of the present invention is characterized in that an aluminum nitride layer is formed on the surface layer of an aluminum base plate.

The manufacturing method of the present invention involves implanting nitrogen ions into the surface of an aluminum base plate in vacuum under the conditions that the energy of the nitrogen ions is 20 KeV or less and the temperature of the base plate at the time of ion implantation is 300°C or less. It is characterized by forming an aluminum nitride layer on the surface layer of the blank.

[Effect]

In the magnetic recording medium substrate of the present invention, since the aluminum nitride layer formed on the surface layer of the aluminum base plate has a hardness, the strength of the substrate is improved and a high-precision smooth surface can be obtained when polished. can get. Furthermore, since the aluminum nitride layer is thermally stable, it does not become magnetic even when exposed to high temperatures. Moreover, the problem of peeling off of the aluminum nitride layer can be ignored.

On the other hand, according to the manufacturing method of the present invention, the above-described substrate for a magnetic recording medium can be manufactured while suppressing deformation, hardness reduction, surface roughness, etc. of the aluminum base plate.

〔Example〕

FIG. 1 is a schematic partial cross-sectional view showing a magnetic recording medium using a substrate according to an embodiment of the present invention.

Components equivalent to those in FIG. 5 are designated by the same reference numerals and their explanations will be omitted. The magnetic recording medium substrate 13 according to this embodiment is formed by forming aluminum nitride N7 on the surface layer of the aluminum base plate 1, that is, from the surface of the base plate 1 in the depth direction.

The material of the base plate 1 may be aluminum or an aluminum alloy such as Al-Mg type or Al-Cu-Zn type, as in the past.

An example of the composition in the depth direction from the surface of the substrate 13 is shown in FIG. There is a single layer of aluminum nitride (AIN) from the surface to a certain depth, and deeper than that there is a layer of aluminum nitride and the base material of the base plate 1, such as aluminum (AIN).
There is a mixed layer with I), and the deeper part is the base material aluminum. However, the depth of the aluminum nitride layer and the mixed layer can be adjusted by the energy of the implanted nitrogen ions, which will be described later.
You can select one that meets the conditions of use in 3.

In the substrate 13 described above, since the aluminum nitride layer 7 formed on the surface layer of the base plate 10 has high hardness, the hardness of the substrate 13 is improved and polishing is performed in the polishing step after forming the aluminum nitride layer 7. When this is done, a highly accurate smooth surface can be obtained.

Furthermore, the aluminum nitride layer 7 is thermally stable and does not become magnetic even when exposed to high temperatures.

Therefore, various methods such as sputtering can be used to form the magnetic film 4.

In addition, since the elementary Fi1 is aluminum-based, even when exposed to high temperatures, the high thermal conductivity of aluminum allows the substrate 1 to
Another effect is that deterioration of the surface of No. 3 can be suppressed.

Furthermore, as shown in FIG. 2, the aluminum nitride layer 7 is not attached to the surface of the base material, which is the blank plate, as in the conventional case, but is attached to the surface layer of the base material, that is, the surface of the base material. Since the aluminum nitride layer 7 is formed in the depth direction, the problem of peeling of the aluminum nitride layer 7 can be ignored. Moreover,
Inside the aluminum nitride layer 7, there is a mixed layer with the aluminum base metal, which acts like a wedge, so that the above-mentioned peeling prevention effect is further enhanced.

By the way, the aluminum nitride layer is coated on the base plate 1 by coating methods such as general plating, vacuum evaporation, and sputtering.
When it is deposited on top, as shown in FIG. 3, the aluminum nitride layer is only deposited on the surface of the aluminum base metal, and its adhesion is not good.

Next, an example of a method for manufacturing the substrate 13 as described above will be explained with reference to FIG. 4. FIG. 4 is a schematic diagram showing an example of an apparatus for carrying out the manufacturing method according to the present invention. A blank plate 1 as described above is housed in a vacuum container (not shown), a heater 10 is provided behind the blank plate 1, and an ion source 8 is provided in front of the heater 10 facing the blank plate 1. .

In the above-mentioned apparatus, after evacuating the inside of the vacuum container to a high vacuum (for example, 10-' to 10-7 Torr), nitrogen ions 9 from an ion source 8 are applied to the surface of the blank plate 1 as follows. When implanted under these conditions, an aluminum nitride layer 7 as described above is formed on the surface layer.

In this case, it is preferable to use a large-diameter brush type ion source as the ion source 8. This is because if such a material is used, nitrogen ions 9 can be uniformly implanted over a large area into the base plate 1, and thereby a uniform aluminum nitride layer 7 can be formed over a large area. It is.

During ion implantation, the base plate 1 is preferably kept at a certain temperature, more specifically at around 100°C.

This is because by implanting ions while annealing the base plate 1, damaged parts such as lattice defects in the aluminum-based metal that is the base material and the formed aluminum nitride layer 7 are reduced. In this case, if the temperature of the base plate 1 does not reach the above-mentioned temperature due to heating by ion implantation, heating by the heater 10 or the like may be used in combination as necessary.

However, the temperature of the base plate 1 during ion implantation is 300°C.
It is preferable to keep it below. This is because if the temperature exceeds 300° C., the hardness of the blank plate 1 decreases or the blank plate 1 deforms.

Further, the energy of the nitrogen ions 9 is preferably 20 KeV or less. This is because if the voltage exceeds 20 KeV, the surface of the blank 1 will become rough due to sputtering phenomena, etc., and more specifically, it is preferably within the range of about 5 to 10 KeV.

Further, the amount of nitrogen ions 9 implanted into the element vi1 is 10
11' ion/cIT12 or less, more specifically 10'
It is preferable to set the value to about 1 ion/cm.
This is because if the OI exceeds 8, the surface of the blank 1 will become rough.

According to the manufacturing method described above, the magnetic recording medium substrate 13 as described above can be manufactured while suppressing deformation of the base plate 1, reduction in hardness, surface roughness, etc.

〔Effect of the invention〕

As described above, in the magnetic recording medium substrate according to the present invention, since the aluminum nitride layer formed on the surface layer of the aluminum base plate has high hardness, the strength of the substrate is improved and when polished, A highly accurate smooth surface can be obtained. Furthermore, since the aluminum nitride layer is thermally stable, it does not become magnetic even when exposed to high temperatures. Moreover, the problem of peeling off of the aluminum nitride layer can be ignored.

Further, according to the manufacturing method according to the present invention, the above-described substrate for a magnetic recording medium can be manufactured while suppressing deformation, hardness reduction, surface roughness, etc. of the aluminum base plate.

[Brief explanation of drawings]

FIG. 1 is a schematic partial cross-sectional view showing a magnetic recording medium using a substrate according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of the composition in the depth direction from the surface of the substrate as shown in FIG. FIG. 3 is a schematic diagram showing an example of the composition near the surface of a substrate by a general coating. FIG. 4 is a schematic diagram showing an example of an apparatus for carrying out the manufacturing method according to the present invention. FIG. 5 is a schematic partial cross-sectional view showing an example of a magnetic recording medium using a conventional substrate.

Claims (2)

[Claims] (1) A substrate for a magnetic recording medium characterized by forming an aluminum nitride layer on the surface layer of an aluminum base plate. (2) By implanting nitrogen ions into the surface of an aluminum base plate in vacuum under the conditions that the energy of nitrogen ions is 20 KeV or less and the temperature of the base plate at the time of ion implantation is 300°C or less, the surface layer of the base plate is 1. A method of manufacturing a substrate for a magnetic recording medium, comprising forming an aluminum nitride layer on a portion of the substrate.