JPS63292418A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To contrive the formation of a thinner protective film suitable for high-density recording and the reduction of a cost and the enhancement in durability and corrosion resistance by forming a polyimide film on the surface of the magnetic layer of a magnetic recording medium and further, providing a solid or liquid lubricating agent thereon. CONSTITUTION:The polyimide is provided on a thin magnetic metallic film provided on a substrate and further, the solid or liquid lubricating agent is provided thereon. Namely, the polyimide film is formed by coating and calcining of a polyamid acid soln. on the thin magnetic metallic film provided on the substrate and thereafter, the solid lubricating agent such as higher fatty acid or the metal salt thereof or higher alcohol, etc. or the liquid lubricating agent such as fluorine or silicone is coated thereon. The water resistance (prevention of corrosion of the magnetic layer by moisture) of the magnetic recording medium provided with the polyimide film is large and, therefore, the formation of the thinner film is possible and the role to the high density recording is large.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording medium that uses a magnetic metal thin film formed on a substrate by plating, sputtering, vacuum evaporation, or other similar methods. be.

(Summary of the Invention) The purpose of the present invention is to form a polyimide on the surface of the magnetic layer of a magnetic recording medium and further provide solid or liquid lubricant to improve running resistance (contact start with repeated head flying and landing). The object of the present invention is to provide a magnetic recording medium with improved durability due to stop (hereinafter abbreviated as C8S) and corrosion resistance at a low cost.

[Conventional technology]

Magnetic recording media are generally of the coating type (based on the γ-FesOs dispersion method), and are coated using sputtering, plating, etc.
It is disadvantageous for high-density recording because it is thicker than a continuous thin film medium and is an intermittent magnetic film with an organic binder interposed. Therefore, in recent years, cobalt alloy 'Fs films produced by plating, sputtering, etc. have been in the spotlight. In addition, since magnetic thin film alone has poor running resistance, carbon retention
It is common to sputter a pattern 2 and apply a lubricant thereon.

To apply a carbon film, W! 70 to improve adhesion
It is necessary to swipe the film, and the total film thickness including carbon is generally required to be about 500λ or more.

[Problem that the invention seeks to solve]

However, with the recent trend toward higher density recording, the distance between the magnetic layer and the head when the head is flying has become a situation that cannot be ignored, and the use of 'R' films made of carbon, etc., is progressing, but there are concerns about running resistance and corrosion resistance. The elements are large.

Further, when applying a chromium or carbon film, a vacuum device is used, which makes it difficult to process a large number of badges, and the manufacturing cost including the manufacturing equipment is high.

Furthermore, in magnetic recording heads, mini-monolithic (Mn--Zn-ferrite) types have been replaced by mini-composite types and thin-film heads that are compatible with higher recording densities. However, the slider materials for the mini combo type and thin film head are CaT i Os and An, respectively.
It is made of Os-T i C and has a fairly high hardness, so the carbon film is easily damaged.

In this case, although improvements have been made in providing a lubricating layer on carbon, significant improvements have not yet been achieved.

Therefore, the present invention aims to solve these problems.
The purpose is to provide a magnetic recording medium that has a thinner protective film suitable for high recording density, lower cost, higher durability, and higher corrosion resistance.

[Means for solving problems]

The magnetic recording medium of the present invention is characterized in that polyimide is provided on a magnetic metal thin film provided on a substrate, and solid lubrication or liquid lubrication is further provided thereon. That is, a polyamide acid solution is coated on a magnetic metal thin film provided on a substrate and fired to form a polyimide film, and then a solid lubricant such as a higher fatty acid or its metal salt or a higher alcohol, or a fluorine-based or silicone film is applied. Apply a liquid lubricant such as a liquid lubricant.

In general, polyimide has better lubricity and is more environmentally resistant than traditional carbon materials. However, like carbon, it is difficult to maintain complete durability when used alone. Therefore, solid or liquid lubrication is applied to complete highly durable media. Chemical bonding of the lubricating layer on the polyimide surface.

Furthermore, it is thought that the polyimide exhibits high lubricity because the lubricant is impregnated into the polyimide due to the unevenness created when air bubbles escape during firing of the polyimide.

Although there is a method of forming polyimide by sputtering, the use of a vacuum device results in very high costs and poor workability.

In addition, a magnetic recording medium provided with a polyimide film has great water resistance (prevention of corrosion of the magnetic layer due to moisture), and therefore can be made even thinner and plays an important role in increasing recording density.

It is desirable that the polyimide film has a thickness ranging from an ultra-thin film of several tens of Angstroms to about 500 Angstroms.

A thickness of 500 Å or more is disadvantageous for high-density recording. (Because the distance between the magnetic layers of the head becomes large) Also, it is desirable that the solid or liquid lubricant provided on the head be 100λ or less. If it is more than 100λ, sticking phenomenon between the head and the disk, that is, stiction, is likely to occur. .

These films can be coated by printing techniques such as spin cord, dipping (uniform speed pulling, spraying, offset method, etc.).

Note that in order to form polyimide, it is desirable to apply the polyamide solution and then bake it at 350° C. or lower to form a polyimide film. Heating at 350° C. or higher for a long period of time changes the magnetic properties, which is not preferable.

As described above, the present invention provides polyimide on a magnetic metal thin film.
Furthermore, it is characterized by providing solid lubrication or liquid lubrication thereon.

[Example 1] A mirror-finished disc-shaped aluminum alloy substrate is coated with non-magnetic alloy (Ni-P) plating to a thickness of about 15 μm, and then polished to a thickness of 10 μm and a surface roughness [fo, 02 μm or less].

Next, after degreasing and acid etching, 500 people plated a magnetic film made of CON N 11P. After drying, the following treatment solution was applied by a constant speed pulling method and baked at 250°C for 30 minutes to obtain a polyimide film.

Furthermore, about 50 people were coated with sodium stearate using the following treatment solution by the isokinetic pumping method.

[Example 2] After setting the above substrate on a polished product finished in the same manner as in Example 1 by magnetron sputtering, the temperature was set at 10'-'Torr.
After evacuation, the substrate was heated to 80° C. and held for 3 minutes. Next, 800 Cr, Co-Ni (Co-20
at%Ni) applied to 800 people, operating pressure crab 4
X10-'' Torr) was sputtered.

Furthermore, using the following treatment liquid, apply by the constant velocity method,
It was baked at 200°C for 30 minutes to obtain a polyimide film.

Treatment liquid I. Semicofine''810 (Toshifurashi) Using the following treatment liquid, a fluorine-based lubricant was applied by a constant-velocity pumping method.

[Example 3] A magnetically plated substrate finished in the same manner as in Example 1 was spin-coded under the following conditions and fired to obtain a 150%
A human polyimide membrane was obtained.

Furthermore, a fluorine-based lubricant was applied using the following treatment liquid by a constant velocity pumping method.

[・Daifukun 5-3 (Example 4) The following processing solution was applied to the magnetic sputtered film finished in the same manner as in Example 2 by the spin code method, and then heated at 180°C.
After baking for 30 minutes, 200 polyimide films were obtained.Furthermore, about 50 films of potassium stearate were coated using the following treatment solution by the isokinetic up method.

[Example 5] The following treatment liquid was applied onto a polyimide lubricant protector finished in the same manner as in Example 4 by a constant-velocity pumping method.

Treatment liquid [・Sogenol a O, 1w% [Comparative Example 1] Cr/C (50λ/200
A sodium stearate lubricant was applied by sputtering under the same conditions as in Example 1.

(Comparative Example 2) Cr/C (100λ740
0 person) was sputtered, and a fluorine-based lubricant was applied under the same conditions as in Example 2.

(Comparative Example 3) Cr/C (100 people, 740
0 person) was sputtered, and a fluorine lubricant was applied under the same conditions as in Example 3.

(Comparative Example 4) Cr/C (100λ740
A potassium stearate lubricant was applied under the same conditions as in Example 4.

(Comparative Example 5) Cr/C (100λ/40
0 person) was sputtered, and Rigturic acid was applied under the same conditions as in Example 5.

[Comparative Example 6] Only stearic acid/sodium acid lubricant was applied on the magnetic film in Example 1 under the same conditions as in Example 1.

(Comparative Example 7) Only a fluorine-based lubricant was applied on the magnetic film in Example 2 under the same conditions as in Example 2.

The quality of the disks described in the above Examples and Comparative Examples was evaluated by durability (C8S test) and moisture resistance test.

In the C8S test, the appearance change and static friction coefficient after C8s@ were determined. (Hefd: Mini component, thin film head) The humidity test is performed by leaving the disc in an environment of 80°C, 90% R, H, measuring the number of missing pits over time, and ending the lifespan when an increase in the number of missing pits is confirmed. I decided that.

As described above, by forming a polyimide film on a magnetic film and applying a solid lubricant or liquid lubricant thereon, durability and moisture resistance were significantly improved.

(Effects of the Invention) HB and media have been on the market for a long time as storage media compatible with high density storage, but their use has been limited to some areas due to concerns about their long-term reliability.

According to the present invention, there is no change in the metal medium even if the storage medium is used under humid conditions, and the mechanical reliability is high, so even if the drive is increasingly miniaturized and used in harsh environments. , the characteristics of both the storage body and the head will not deteriorate as a result.

Furthermore, since the protective film can be made thinner, it is easier to achieve higher density recording, and it is also useful for more advanced perpendicular magnetic recording.

As described above, it has become possible to provide a memory medium with high density recording, high corrosion resistance, high durability, and low cost.

that's all

Claims (1)

[Claims] A magnetic recording medium characterized in that polyimide is provided on a magnetic metal thin film provided on a substrate, and solid or liquid lubrication is further provided on the polyimide.