JPS61151836A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled magnetic recording medium having excellent surface lubricity and durability without necessitating a protective film by providing the coated layer of a lubricant on a magnetic thin film provided with a group of fine recesses. CONSTITUTION:A metallic thin film is formed on a magnetic thin film 2, and heated to form crystal grains in the metallic thin film. After the metallic film is masked, the lower magnetic film is ion-etched to form a fine recess 21. A dilute liq. of perfluoroalkyl polyester is applied on the magnetic thin film 2 on which the recess 21 is formed to form a lubricant layer 3 having about 0.01mum thickness. A part of the lubricant of the lubricant layer 3 is trapped in the recess 21 on the magnetic film. Consequently, a sufficient amt. of the lubricant layer is formed in total in spite of the thin thickness of the layer. Accordingly, stabilized lubricity to the magnetic head can be kept for a long period.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to the improvement of a magnetic recording medium used in a magnetic disk drive, and more specifically, to a magnetic recording medium that is capable of high-density recording and has good surface lubricity. It concerns a new recording medium structure.

[Conventional technology]

As a magnetic recording medium capable of this kind of high-density recording,
It is known that a continuous magnetic thin film 12 of r-Fezes is formed by sputtering on a nonmagnetic substrate 11 as shown in the figure, and a lubricant 13 is further applied thereon.

By the way, in such a recording medium configuration, when a lubricant is applied directly onto the magnetic thin film, if the surface of the magnetic thin film has good smoothness, a phenomenon occurs in which the magnetic head is attracted to the surface. Here, adsorption refers to the fact that the magnetic head adheres to the surface of the medium. If the recording medium is rotated in such an adsorption state, a crash may occur due to stick-slip.

This stick-slip can be reduced by applying a thin layer of lubricant, but this lubricant layer structure cannot be expected to be effective in terms of durability of the medium and head. Furthermore, control of the thickness of the lubricant film lacks reproducibility and manufacturability due to its small variable range, and is nearly impossible in a mass production process.

Therefore, a recording medium has been proposed in which a porous protective film 14 made of silicon dioxide (Sing) is formed on a γ-FetOsiff thin film 12 as shown in FIG. 3, and a lubricant 13 is applied thereon. This recording medium has a structure in which the lubricant is retained in the protective film 13 rather than on the surface, so the lubricant has a large amount of impregnated carbon, which makes it excellent in wear resistance, and it also attracts the magnetic head. The phenomenon can be prevented. However, in order to retain sufficient lubricant in the protective film, recesses of appropriate depth are required, and specifically, the thickness of the Si0g protective film 14 is required to be 0.05 μm or more.

[Problems to be solved by the invention] However, in recent magnetic disk drives, in order to increase the recording density, it is required to reduce the gap between the magnetic head and the recording medium, that is, the flying height of the head. . Figure 3 shows the relationship between the head flying height and the recording density (Ds.) in a recording medium with a magnetic film with a thickness of 0.15 μm, and it can be seen from this that the recording density can be increased as the head flying height becomes smaller. . Note that the head flying height of current disk drives is on the order of 0.2 μm, and in the future, if it is to be further reduced, the protective film thickness of 0.05 μm will be required.
.mu.m causes a big problem, and therefore, a recording medium with a protective film as shown in FIG. 3 is not suitable for high recording density.

In view of the above-mentioned conventional situation, it is an object of the present invention to provide a magnetic recording medium that does not require a protective film and has good surface lubricity and durability.

[Means for solving problems]

In order to solve the above-mentioned problems, this invention provides a large number of fine recesses on the upper surface of a γ-Fezes magnetic thin film formed on a non-magnetic disk-shaped substrate, and further provides a magnetic film with a group of fine recesses. It is characterized in that a lubricant coating layer is provided on the thin film.

[Effect]

The group of fine recesses on the surface of the γ-FetOxln thin film allows a sufficient amount of the lubricant coating layer to be formed on the surface of the magnetic thin film even if the thickness of the lubricant film is reduced in order to trap the lubricant. Durability can be improved, and since a protective film is not required, the effective flying height of the magnetic head can be reduced.

〔Example〕

FIG. 1 is a sectional view of a main part showing an example structure of a magnetic recording medium according to the present invention, and 1 is an aluminum alloy.

A disk-shaped substrate made of glass, ceramic, etc., 2 is a film with a thickness of 0.2 mm formed by sputtering on the disk-shaped substrate.
It is an r -Pe2O3 magnetic thin film with a thickness of 15 to 0.2 pm, and has many depressions (concave portions) 21 with a diameter of 5 to 20 μm and a depth of 0.04 to 0.05 μm on the surface. Note that this minute recess 21
can be formed using the manufacturing method previously proposed by the present inventors in Japanese Patent Application No. 58-243179. Briefly, a metal thin film is formed on the magnetic thin film 2, and then heated to form a metal film. It can be formed by a manufacturing method including a step of forming crystal grains inside and then ion-etching the lower magnetic thin film using the metal film as a mask. Further, it is desirable that the depth of the recesses 21 be 25% or less of the thickness of the magnetic thin film; if the depth is greater than this, the recesses will have the same effect as a medium defect and cause a missing error.

r-FetOx with the recess 21 formed in this way
A diluted solution of perfluoroalkyl polyether (trade name Talitox 143AD) is applied on the flI thin film 2 to form a lubricant layer 3 with a thickness of about 0.01 μm. This lubricant layer 3 has a part of the lubricant in the recesses 2 on the magnetic film.
Therefore, despite the thin layer thickness, the lubricant layer constitutes a sufficient amount in total. In short, the trapped lubricant acts to replenish the lubricant that decreases over time due to contact with the magnetic head. Therefore, it is possible to provide stable lubricity for the magnetic head over a long period of time.

In addition to the above-mentioned perfluoroalkyl polyether, examples of lubricants include higher fatty acids, fatty acid esters, higher alcohols, and fluorinated products thereof.

Silicone oil can also be used.

〔effect〕

As is clear from the above description, the magnetic recording medium of the present invention has a structure in which a depression is provided in the γ-Fears magnetic thin film and a part of the upper lubricant layer is trapped in the depression. A sufficient amount of lubricant layer can be formed without the need for a protective film, achieving good lubricity and high durability for the magnetic head, as well as a low flying head, resulting in high output and high recording density. can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part showing an embodiment of a magnetic recording medium according to the present invention, FIGS. 2 and 3 are cross-sectional views of main parts of a conventional magnetic recording medium, and FIG. Recording density (
D! . ) is a diagram showing the relationship between 1: Non-magnetic disk-shaped substrate, 2: γ-Fetus magnetic thin film, 3 magnetic thin film layer 3: Lubricant Figure 1 Figure 2

Claims (3)

[Claims] (1) In a recording medium configuration in which a γ-Fe_2O_3 magnetic thin film is formed on a non-magnetic disc-shaped substrate, the upper surface of the magnetic thin film has a large number of minute recesses, and the magnetic thin film further has a group of fine recesses. A magnetic recording medium characterized by being provided with a lubricant coating layer. (2) The nonmagnetic substrate is aluminum alloy, glass,
The magnetic recording medium according to claim (1), characterized in that it is made of any one of ceramics. (3) Claim (1), wherein the fine recess has a diameter of 5 μm to 20 μm and a depth of 25% or less of the thickness of the γ-Fe_2O_3 magnetic thin film; or the magnetic recording medium according to any one of paragraph (2).