JP2959802B2 - Method of manufacturing continuous magnetic film type magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A method of manufacturing a continuous magnetic film type magnetic recording medium used for a magnetic disk device or the like, particularly, a continuous magnetic film type magnetic recording / reproducing information with a CSS type flying magnetic head. Regarding the method of manufacturing a recording medium, in a continuous magnetic film type magnetic recording medium having a good lubricant holding property and excellent abrasion resistance and magnetic properties, a protrusion for reducing a sliding area with a core slider is missing. A magnetic recording layer consisting of a continuous magnetic film is formed on a non-magnetic substrate with the aim of realizing a magnetic recording medium that is difficult to mix. A solvent containing silicon is mixed with a substance that is easily decomposed or evaporated. After that, it is applied on a substrate having the continuous magnetic film, the solvent is raised along the surface of the substance from the film surface of the solvent, and then, by baking, the solvent is cured and cured. Previous After a protective film is formed by simultaneously decomposing and evaporating a substance that is easily decomposed or thermally evaporated, a surface of the protective film is polished to remove the tips of the projections, and then the lubricant is washed. Coating.

[Industrial applications]

The present invention relates to a method of manufacturing a continuous magnetic film type magnetic recording medium used for a magnetic disk device and the like, and more particularly to a method of manufacturing a continuous magnetic film type magnetic recording medium in which information is recorded / reproduced by a CSS type flying magnetic head. .

[Technological background]

2. Description of the Related Art In recent years, magnetic disk devices used in data processing devices and the like have rapidly increased in data recording density and increased in capacity. In addition, from the viewpoint of high speed and economical efficiency, the size of the devices has been decreasing. With the demand for such a high recording density, a recording medium is changing from a conventional coating film to a continuous magnetic film.

That is, conventionally, a magnetic powder is mixed in a binder such as a synthetic resin and the like is spin-coated on an aluminum substrate to form a coating film, thereby constituting a magnetic film of a magnetic recording medium. On the other hand, a continuous magnetic film is formed by forming a magnetic material such as iron or an iron-cobalt alloy on a substrate by a method such as sputtering, vapor deposition, or plating, and does not include a binder (binder). It is called a simple magnetic film (continuous magnetic medium). This continuous magnetic film has better magnetic properties than a non-continuous magnetic film containing a binder such as a synthetic resin like a conventional coating film,
The manufacturing process is also simplified. Also, the recording density has improved dramatically,
As a high recording density medium, one having excellent properties has been obtained. In particular, a ferrite oxide film is also hard as a material, has good corrosion resistance, and is evaluated as a very good magnetic recording medium. .

By the way, as with the conventional magnetic disk drive, the magnetic disk drive using the continuous magnetic film also has a CSS (Contact S
tart Stop) method is adopted. Therefore, usually, the magnetic head floats above the disk surface to read and write.
In a state where no levitation force is generated, such as when the magnetic recording medium starts and stops rotating, the surface of the magnetic recording medium and the core slider of the magnetic head come into contact and slide. As a result, the surface of the magnetic recording medium in the CSS zone where the magnetic head is in sliding contact wears out, and the abrasion powder diffuses over the entire surface of the magnetic recording medium, causing a head crash. Therefore, it is necessary to minimize wear of the surface of the magnetic recording medium so as not to generate abrasion powder.

(Various methods for improving the wear resistance of the media surface)

Conventionally, the following method has been employed to prevent the wear of the magnetic recording layer.

A protective film such as silicon oxide (SiO ₂ ) or resin is provided on the surface of the magnetic recording layer with a thickness such that the distance between the magnetic head and the magnetic recording layer does not become too large.

In order to reduce the wear at the time of magnetic head contact sliding,
A lubricant is applied on the magnetic recording layer or the protective film to improve the sliding of the magnetic head slider.

When the lubricant is applied, the magnetic head slider sticks to the surface of the magnetic recording medium with the lubricant, and when the magnetic recording medium starts rotating, there is a possibility that the support mechanism of the magnetic head is damaged or a head crash occurs. Therefore, for the purpose of preventing this sticking, as shown in FIG. 4A, the surface of the protective film 2 provided on the magnetic recording layer 1 is formed by a method described in JP-A-56-22221. Are provided with countless projections 3. Since the lubricant is impregnated in the gap between the projections 3 and the lubricant film between the slider and the magnetic recording medium is thinned, the adhesion is eliminated and the friction coefficient is smaller than that of the smooth surface. 4
Is an aluminum substrate, and 5 is an alumite layer formed on its surface.

A porous film is used as the protective film 2 of the magnetic recording layer 1 or the fourth
As shown in FIG. 2B, fine holes 6 are provided and impregnated with a lubricant.

As described in JP-A-56-22219, in a coating-type magnetic recording medium, paraffin particles are kneaded and applied to a magnetic paint, and baked, so that fine particles for retaining lubricant can be obtained. Although a method of forming irregularities directly on the surface of a magnetic coating film has been proposed, it cannot be applied to a continuous magnetic film type magnetic recording medium as in the present invention.

[Problems of various methods]

However, all of these methods have the following problems. That is, wear cannot be prevented by simply providing a protective film as described above. Since the alumite surface of the substrate is finished to a mirror surface and a magnetic film is provided thereon, the surface of the magnetic film also becomes an extremely smooth surface in a mirror state. Therefore, the protective film on the magnetic film is also smooth, and when the magnetic head does not float and is in sliding contact with the protective film, dust is generated due to the wear of the protective film, causing a head crash which is a fatal obstacle. May trigger.

If the lubricant is applied to improve the slip as described above, the coefficient of friction is small and effective during the initial period, but if the lubricant is consumed over time, the lubricating action is reduced and abrasion powder is generated.
However, if a large amount of lubricant is applied, the slider sticks to the surface of the magnetic recording medium with the lubricant when the magnetic recording medium stops and is in contact with the slider, so the next time the magnetic recording medium starts rotating In addition, there is a possibility that a head crash may be caused by an impact when the magnetic head is suddenly peeled off from the surface of the magnetic recording medium, or a gimbal supporting the magnetic head may be damaged.

If the innumerable projections 3 are provided on the surface of the magnetic recording medium as described above, the lubricant is impregnated into the gaps between the projections, so that the problem in the method can be reduced to some extent, but it flows outward due to centrifugal force and disappears. I do. Therefore, the impregnating agent cannot be stably and uniformly maintained on the entire surface. Therefore, the life of the lubricant is short, and it cannot withstand long-term use.

If the protective film is made porous as described above, the lubricant is less likely to move and the lubricant has better durability. However, since the surface of the protective film is smooth, the abrasion resistance during sliding decreases.

Further, in the method of kneading and baking paraffin particles in a magnetic paint as described in the above-mentioned JP-A-56-22219, in addition to the presence of non-magnetic resin in the magnetic film, Since a cavity due to traces occurs,
This degrades the properties as a magnetic film, and is not applicable to a medium having a high recording density. Moreover, since the magnetic paint has a high viscosity, it is difficult to uniformly disperse the paraffin particles, and there are problems such as concentration of cavities, bit errors, and a decrease in S / N ratio. Since the magnetic paint has a high viscosity, it is also difficult to form projections along the ridges of the paraffin particles using surface tension. In particular, in the case of a medium in which a continuous magnetic film is formed by a method such as sputtering or vapor deposition as in the present invention, a method of kneading paraffin particles in a magnetic paint cannot be applied.

[Conventional technology]

Therefore, Japanese Patent Application No. 58-113517 proposes a method as shown in FIGS.

That is, a continuous magnetic film made of γ-Fe ₂ O ₃ or the like is formed on a non-magnetic substrate such as an alumite substrate, and SiO ₂ for improving adhesion is formed on the continuous magnetic film as necessary. Is formed. Then, after mixing a solvent containing silicon and a substance that is easily decomposed or thermally evaporated, this mixed solution is mixed with the Si.
It is applied on an O ₂ film so that the solvent rises along the surface of the substance from the film surface of the solvent. After a while
By baking, the curing of the solvent and the decomposition and evaporation of the thermally decomposable or thermally evaporable substance are performed at the same time, thereby forming projections and isolated recesses on the planar protective film surface. Apply lubricant to.

Liquid paraffin is suitable as a substance that is easily decomposed or evaporated.

FIG. 6 is a sectional view showing a continuous magnetic film type magnetic recording medium manufactured by this method. The surface of the aluminum substrate 4 is oxidized to form an alumite layer 5, and the magnetic film 1
Γ-FeO ₃ or the like is provided by a method such as sputtering. When the protective film 2 is formed on the magnetic film 1 by the above-described method, countless protrusions 7 and concave portions 8 are formed. L is a position of the planar protective film surface 10 formed at a position separated by a predetermined film thickness from the magnetic film 1, and the position of the protective film surface 10 is hereinafter referred to as an intermediate level. With respect to the intermediate level L, protrusions 7 which are traces of decomposition / evaporation of the easily decomposable or heat-evaporable substance are raised in a crater shape, and a spherical concave portion 8 is formed at the center thereof. It is formed in a state recessed from the level L.

[Problems to be solved by the invention]

Thus, according to this method, traces of the evaporated liquid paraffin become concave portions and protrusions. That is, since the solvent containing silicon has a low viscosity and is likely to protrude along a sphere of liquid paraffin or the like due to surface tension, after the liquid paraffin or the like is decomposed and evaporated, a projection 7 projecting from the planar protective film surface 10; An infinite number of independent concave portions 8 depressed from the protective film surface 10 are formed. A low-viscosity silicon-containing solvent is mixed with easily decomposable or heat-evaporable substances such as liquid paraffin, so that it can be easily and uniformly dispersed in the solvent, and the entire surface of the protective film can have uniform irregularities. Can be formed.

In addition, by appropriately selecting the amount and components of the liquid paraffin to be added, the depth of the trace of evaporation of the liquid paraffin and the height of the protrusions are variously uneven, so that a number of protrusions and a protective film higher than the protective film surface are formed. Innumerable concave portions lower than the surface can be obtained.

Unlike a method in which paraffin particles are kneaded in a magnetic paint and baked, in the step of forming a protective film on the magnetic film, irregularities are formed on the surface of the protective film, so that the present invention can be applied to a medium of a continuous magnetic film. Also, even when applied to a medium of a discontinuous magnetic film such as a coating type medium, no void is formed in the magnetic coating, so that the nonmagnetic region in the magnetic coating increases as in the conventional method. It is suitable for a medium with a high recording density without deteriorating the magnetic characteristics.

However, in the CSS zone, when the core slider H of the magnetic head slides as shown by a chain line, the tips of the protrusions 7,... For this reason, there is a possibility that a missing object at the pointed end diffuses into the data zone, and information in the data zone is destroyed due to a head crash.
In particular, since the missing object is larger than ordinary wear powder, the influence of head crash is large.

The technical problem of the present invention is to focus on such a problem, and in a continuous magnetic film type magnetic recording medium having a good lubricant holding property and excellent abrasion resistance and magnetic properties, a sliding area with a core slider. An object of the present invention is to realize a magnetic recording medium in which protrusions for reducing the density are less likely to drop out.

[Means for solving the problem]

FIG. 1 is a process chart for explaining the basic principle of a method for manufacturing a continuous magnetic film type magnetic recording medium according to the present invention. First, after forming a continuous magnetic film on a non-magnetic substrate, a solvent containing silicon,
A mixed solution obtained by mixing a substance that is easily decomposable or thermally evaporated is applied so that the solvent rises along the surface of the substance from the film surface of the solvent. Then, baking is performed to simultaneously cure the solvent and decompose and evaporate the thermally decomposable or thermally evaporable substance to form a protective film. As a result, projections protruding from the protective film surface and concave portions depressed from the protective film surface are formed. Next, by performing polishing such as burnishing,
After removing the tips of the projections, wash and apply a lubricant.

[Action]

By baking after the application of the mixed solution, protrusions protruding in a crater shape are formed, and the tips of the protrusions are removed by polishing. Since the lubricant is applied after cleaning after polishing, the lubricant is held in the concave portion which is depressed from the protective film surface.

Since the prone portion of the projection tip is easily removed by polishing in advance, during operation after the device is completed,
Even if the core slider of the magnetic head slides into the CSS zone during CSS operation, there is no possibility that the protrusion will be missing. Therefore, a missing object that causes a head crash hardly occurs, and information can be recorded / reproduced stably.

Further, by removing the tip of the protrusion, the distance between the magnetic film and the magnetic head is reduced, so that the efficiency of information recording / reproduction is improved, and the magnetic head is suitable for a magnetic recording medium requiring a high recording density. I have.

〔Example〕

Next, how the method for manufacturing a continuous magnetic film type magnetic recording medium according to the present invention is actually embodied will be described with reference to examples.

FIG. 2 is an enlarged sectional view showing a surface state of the magnetic recording medium in a manufacturing process, and FIG. 3 is a process chart.

As described in FIG. 5, after forming γ-Fe ₂ O ₃ or the like as a magnetic film 1 on the alumite layer 5 by a sputtering method,
The processing is performed in the following order.

(1) Application of mixed liquid: A mixed liquid containing silicon (Si) and liquid paraffin is spin-coated on this magnetic film 1 at 1000 RPM as follows.

A silicone resin belonging to polysilsesquioxane (the one having a relatively small ladder portion) and called a glass resin (trademark of Owens Illinois): 2% acetic acid ethylene glycol monoethyl ether: 50% xylene: 17% acetic acid Ethyl: 31% Liquid paraffin: 0.3% of total amount (2) Baking: After applying the mixed solution, baking is performed at 200 ° C to 350 ° C for 1 to 5 hours.

As a result, as a trace of evaporation of liquid paraffin,
As shown in FIG. 2B, protrusions 7 projecting from the intermediate level L and concave portions 8 recessed from the intermediate level L are formed. That is, when the mixed liquid having the above composition is applied, as shown in FIG. 2 (a), the liquid paraffin, which is a heat-evaporable substance, becomes spherical as shown by a, and the spheres a of each liquid paraffin are connected to each other. Because of the repulsion, countless liquid paraffin spheres a are generated on the mixed solution b. Mixture b is 2% silicone resin
Due to its low degree of viscosity and low viscosity, it is rich in fluidity unlike magnetic paints. Therefore, the sphere a of the liquid paraffin is easily adsorbed by the surface tension, and a spherical depression is formed at a contact portion with the sphere a of the liquid paraffin, and the outer periphery of the dent rises like a crater. Therefore, when the mixture b is cured by baking, solvents such as ethylene glycol monoethyl ether acetate, xylene and ethyl acetate in the mixture b decompose and evaporate, and the Si (OH) ₄ in the glass resin changes. do it
Only SiO ₂ remains, and the SiO ₂ protective film 2 is formed. At the time of baking, spherical liquid paraffin a which is a heat-evaporable substance
Easily decomposes and evaporates, so that the traces remain as a crater bottom-shaped spherical concave portion 8 and a crater edge-shaped raised portion 7 as shown in (b). The spherical concave portion 8 is depressed from the plane intermediate level L, and the projection 7 composed of a raised portion protrudes from the plane intermediate level L.

(3) Burnish: A solution obtained by diluting the fluorinated oil with Fluorinert is spin-coated on the medium surface at 700 RPM, and then the medium is rotated at 1300 RPM, and a wrapping tape (alumina particle size 9 μm) is pressed with a load of 400 g against a bar. Nish. (C) shows a state after the burnishing, in which the tip of the projection 7 is removed by the burnishing, and the projection becomes a projection without a tip like 7a.

Burnishing can also be performed using a wrapping tape coated with a lubricant.

(4) Application of lubricant: After washing, the chipped portion of the tip is removed, and after drying, a solution obtained by diluting the fluorinated oil to 0.03% with Fluorinert is applied as a lubricant.
A continuous magnetic film type magnetic recording medium as shown in (d) was completed. When the magnetic recording medium is rotated at a high speed after the lubricant 9 is applied, the lubricant on the protective film surface 10 at the intermediate level L is removed by centrifugal force, and the lubricant 9 in the isolated recess 8 is held for a long time. You.

[Evaluation of Medium of Example]

The levitation test was performed on the medium burned by the method of the present invention and the medium not burnished as described above. The evaluation of flying performance is performed by attaching an AE element or a piezo element to the magnetic head, loading the magnetic head on a stationary medium, and rotating the medium. Was monitored by monitoring the state of contact with the medium.

As a result, the medium without conventional burnishing as shown in FIG. 6 stopped contacting at 8 m / s,
The media burnished by the method of the invention lost contact at 6.6 m / s. In other words, the burnished product did not come into contact even at a low speed, indicating that the flying characteristics were good, and the effect of the burnished product was recognized. In addition, because of the good levitation property, the medium does not come into contact with the medium surface quickly, but even during sliding, since the point is removed in advance as described above, a missing object is hardly generated.

When the magnetic disk medium was subjected to a high-speed and high-load reverse rotation test, which is a conventional acceleration evaluation method, it showed a strength of 50 times or more. The strength of the protective film is remarkably improved as compared with the case where a normal magnetic disk medium cannot withstand even once. In particular, since the sharp points that are easily dropped are removed in advance, even if the CSS operation of the magnetic head is frequently repeated, a head crash may occur with a large missing object as in the past, causing serious damage to the data zone There is no. Fluorinated oils such as Krytox (trademark of DuPont) could not be applied to the conventional continuous magnetic film in terms of strength and friction, but were protected by the method of the present invention. The film can be applied. Moreover, it does not cause sticking and has excellent seismic wear resistance.

By changing the solvents such as ethylene glycol monoethyl ether acetate, xylene, and ethyl acetate, the surface shape and film thickness of the protective film become various due to the difference in the boiling point of the solvent used, Even the weight of paraffin can be varied. As the solvent, in addition to the above, methyl isobutyl ketone, diacetone alcohol, butanol, air mill alcohol,
Cyclohexanol and the like can be used. Glass resin is
It is a silicon compound mainly composed of Si (OH) ₄ having a Milanol structure in a solvent of ethanol and ethyl acetate, and is a solvent containing silicon (Si).

As an application of this embodiment, the magnetic film 1 is formed by sputtering.
When the above treatment is carried out after depositing SiO ₂ at about 50 to 300 °, the adhesion between the protective film having projections and concave portions and the magnetic film is improved.

〔The invention's effect〕

As described above, according to the present invention, on the magnetic recording layer,
A protective film material containing silicon and a substantially spherical substance such as liquid paraffin that is easily decomposable or thermally evaporated are mixed and applied, and then baked to form an intermediate layer on the surface of the magnetic recording layer. After forming a myriad of microscopic protrusions higher than the level and microscopic independent depressions depressed from the intermediate level, a method of removing the tips of the protrusions with a wrapping tape coated with a lubricant is adopted. For this reason, the problem that a missing piece at the tip is generated particularly in the CSS zone and scatters in the data zone to cause a serious head crash is solved.

According to the method of the present invention, a low-viscosity protective film material can be protruded along a sphere such as liquid paraffin to form a protruding portion reliably and smoothly from the surface of the protective film. Easy to do. However, since the protruding end is polished as described above, a magnetic recording medium having excellent wear resistance can be obtained. Moreover, by removing the protruding end, the distance between the magnetic film and the magnetic head is reduced, so that the efficiency of information recording / reproduction is improved, and a magnetic recording medium with a high recording density can be obtained.

In addition, since the polishing after forming the protective film is performed using a wrapping tape coated with a lubricant of the same material as the lubricant finally applied to the medium, shavings being polished are applied to the wrapping tape. Washed away by the lubricant, and
Since the lubricant at the time of polishing does not need to be completely washed off at the time of cleaning, the cleaning time can be shortened.

[Brief description of the drawings]

FIG. 1 is a process diagram illustrating the basic principle of a method for manufacturing a continuous magnetic film type magnetic recording medium according to the present invention. FIGS. 2 and 3 are embodiments of a method for manufacturing a continuous magnetic film type magnetic recording medium according to the present invention. FIG. 2 is an enlarged sectional view showing a surface state of a magnetic recording medium in a manufacturing process, FIG. 3 is a process diagram, FIG. 4 is a partial sectional perspective view showing a surface state of a general magnetic recording medium, FIG. 5 is a process chart showing a method of manufacturing a conventional continuous magnetic film type magnetic recording medium, and FIG. 6 is a sectional view of a continuous magnetic film type magnetic recording medium manufactured by a conventional method. In the figure, 1 is a magnetic recording layer (continuous magnetic film), 2 is a protective film, 4 is an aluminum substrate, 5 is an alumite layer, 7 is a protrusion before polishing, 7a is a protrusion after polishing, 8 is a concave portion, and 9 is lubrication. L, an intermediate level; 10, a protective film surface; a, a liquid paraffin sphere; and b, a mixed solution.

Claims (1)

(57) [Claims] A magnetic recording layer comprising a continuous magnetic film is formed on a non-magnetic substrate, and a silicon-containing protective film material is mixed with a thermally decomposable or thermally evaporable substantially spherical substance. Is applied on a substrate having the continuous magnetic film, and the protective film material is attached to the surface of the substantially spherical substance so as to be higher than the surface of the film formed by the protective film material. Thereby, the protective film is formed by simultaneously performing the curing of the protective film material and the decomposition and evaporation of the thermally decomposable or thermally evaporable substantially spherical substance, and applying a lubricant to the protective film. Polishing while applying a load with wrapping tape to remove the tip of the ridge,
Then, washing and applying a lubricant are provided, and a method for producing a continuous magnetic film type magnetic recording medium is provided.