JPH03141016A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To suppress the flattening of the protective film of the magnetic recording medium by previously forming waviness of the pitch narrower than the rail width of the core slider of a magnetic head, subjecting the surface thereof to a texture treatment and forming a magnetic film and the protective film. CONSTITUTION:The core slider of the magnetic head is usually provided with the core on a center rail 23 provided between side rails 22 on both sides and is formed with a gap to record and reproduce information. The very small ruggedness by the texture treatment, i.e. the waviness 24 where grooves 19 and peaks 20 exist and which has the pitch W smaller than the rail width R of the side rails 22 is formed on a nonmagnetic substrate 1 of the magnetic recording medium. The core slider 21 first comes into contact only with the peak parts 25 of the waviness and the protective film 4 wears and flattens successively as the medium is used. The valley parts 26 of the waviness do not, however, come into contact with the core slider 21 and, therefore, the area is small and as a result, the increase in the coefft. of friction on the medium surface in a short period of time does not arise.

Description

[Detailed Description of the Invention] [Summary] Regarding a thin-film magnetic recording medium, the present invention aims to suppress flattening of a protective film in a textured magnetic recording medium. In a thin-film magnetic recording medium in which a magnetic thin film is provided after processing, undulations with a pitch narrower than the rail width of the core slider of the magnetic head are formed in advance, and texture processing is performed on the undulations to form a magnetic film and a protective film. The structure is configured to provide a membrane.

[Industrial application field]

Magnetic recording media, which are the recording media in magnetic disk devices, are available in two types: coated type, which is a non-magnetic disc coated with magnetic paint, and type that is made by coating a magnetic thin film of Co-Ni or co-Pts iron oxide. There is a thin film type. The present invention relates to the latter thin film type magnetic recording medium.

[Texture processing]

FIG. 5 is a sectional view showing the entire structure of a conventional thin film magnetic recording medium. 1 is a substrate (disk) made of a non-magnetic material such as aluminum, on which a base film 2, a magnetic film 3, and a protective film 4 are laminated in this order.

FIG. 6 is a diagram showing a cross-sectional structure of a conventional thin film magnetic recording medium, in which the magnetic film 3 is formed of iron oxide (T Fezes). The substrate 1 is made of aluminum, and its surface is oxidized to form an alumite (AlzOs) film, which serves as a base film 2.

Magnetism 1f5!3 is 7-Fe, 0. It is formed using the sputtering method. The protection M4 is formed by sputtering carbon or 5ift.

As the magnetic film 3, in addition to iron oxide (y-FezOz), CoNi, CoNiCr, CoCrTa, etc. are used. Cr is used as the base film. Alternatively, AI is used as the substrate I and N1-P
The base film 2 is made by plating or alumite treatment.

In order to form this magnetic M3, a method as shown in FIGS. 7 to 9 is adopted. Figure 7 shows °“stationary facing type°”
In this method, ring-shaped target targets 51, 52 are arranged on both sides of the substrate 1, and the centers of the substrate I and the ring-shaped targets 51, 52 are aligned. Therefore, since sputtering is performed on the substrate l in the radial direction from the center under the same conditions, the magnetic properties of the magnetic film are uniform throughout the circumferential direction, and information can be recorded/reproduced accurately.

Figure 8 shows a stationary type that rotates the board;
Targets 61, 62 are arranged on both sides of the substrate 1. In this method, since the targets 61 and 62 are not point symmetrical with respect to the center of the substrate l, uniform magnetic characteristics cannot be obtained in the circumferential direction of the substrate l.

Therefore, by rotating the substrate 1, the deposition conditions are made uniform and the magnetic properties are made uniform. however,
Dust generation from the sliding part that rotatably supports the substrate l may cause defects, and this is impractical.

FIG. 9 shows a method of performing sputtering on a large number of substrates 1 at the same time, which is called a pass-through method or an in-line method. 7 is a support plate, and each circular hole of the support plate has a substrate l...
is supported for insertion. The support plate 7 then moves between the targets 61, 62. In this method, magnetic films can be sputtered on many substrates at the same time, but since sputtering is not performed point-symmetrically with respect to the center of each substrate l..., the magnetic film is The characteristics are not uniform, causing problems in recording/reproducing information.

FIG. 10 is a diagram showing a deposited pattern in this pass-through sputtering method, in which (a) is a plan view and (b) is a side view of the substrate. Since particles are scattered in all directions from the targets 61 and 62, when the substrate 1 passes between the targets 61 and 62, at the first point when the substrate l enters between the targets 61 and 62, the arrow al As shown in the figure, particles fly obliquely to the substrate 1 and are deposited thereon.

In other words, as shown in b), the front and rear regions 1a of the substrate l,
In lb, particles fly in the radial direction to the substrate l,
be coated.

However, in the upper and lower regions 1c and ld of the substrate l,
Particles fly toward and adhere to the substrate 1 in the circumferential direction. As described above, since the adhesion conditions change approximately every 90 degrees on the substrate 1, there is a problem in that the magnetic properties change in the circumferential direction of the substrate 1.

Therefore, before forming the base film 2 of the substrate 1, fine scratches are made in the circumferential direction on the surface of the substrate 1, called texture, and the base film 2 and the magnetic film 3 are formed on top of the scratches. Efforts are being made to improve the magnetic properties. Note that the base film 2 can also be textured. In this way, by performing texture processing before forming the magnetic film,
The axis of easy magnetization of the magnetic crystals in the magnetic film is oriented in one direction of the texture, improving magnetic properties due to shape anisotropy, and improving lubricity and reducing adsorption by reducing the contact area between the media surface and the magnetic head. Prevention is possible.

[Texture processing equipment]

FIG. 11 is a perspective view showing a conventional texturing device. 1 is a mirror finished substrate, 200 to 30
A scratch t in the circumferential direction is made on the surface of the substrate 1 by pressing an abrasive tape 9 onto the substrate 1 rotating at 0 rpm while supplying abrasive, cooling and lubricant through a nozzle 8. At this time, as the abrasive tape 9, a tape to which hard powder such as alumina is adhered is used, or it is used in combination with some abrasives.

Note that the abrasive tape 9 is fed out from the feeding roll 10, passes through the guide roll 11, the pressure roller 12, the guide roll 13, the capstan 14 and the pinch roller 15, and is wound up by the winding roll 16. A new surface is constantly supplied to the substrate l side.

After performing the texture processing in this manner, the base film 2 and the magnetic l! 3. Layer the protective film 4. At this time, even if the thickness of both the base film 2 and the magnetic film 3 is combined, it is as thin as about 2000 to 3000, so the magnetic film 3
A thin uneven film follows the unevenness caused by the texture treatment, and the magnetic material is oriented.

In such a conventional texture processing device, whether using an abrasive tape or tape processing using free abrasive grains, a rubber 17 with a hardness of 40 to 60 degrees is used as the roller 12 that presses the tape against the processing surface, as shown in FIG. the metal roller 1
8 is used, and an abrasive tape 9 is pressed against the processed surface.

[Conventional technology]

FIG. 13(a) is a cross-sectional view showing the state of a conventional magnetic recording medium after texture processing. When texturing is carried out using the apparatus shown in FIG. 11, countless irregularities are formed in the radial direction at a fine pitch p on a nonmagnetic substrate l. 19 is a texture groove, and 20 is a texture mountain. FIG. 13 (9) shows a magnetic recording medium in which a magnetic film 3 and a protective film 4 are laminated on this textured uneven surface with an underlying film 2 interposed therebetween.

[Problem to be solved by the invention]

To record/reproduce information on this magnetic recording medium, a magnetic head is levitated above the magnetic recording medium, but during long-term use, the magnetic head comes into contact with the surface of the magnetic recording medium. As shown in FIG. 14, the protective film 4 is worn and the textured grooves are clogged with abrasive materials, which ultimately results in a loss of protection! The unevenness on the surface of the film 4 disappears and becomes flat, and the contact area between the medium surface and the magnetic head increases, making it difficult to maintain lubricity and prevent adsorption. In particular, C where the core slider makes sliding contact with the medium surface.
These problems become noticeable in the 8S zone.

Furthermore, the planarization of the protective film does not proceed uniformly in all magnetic recording media, but varies.

That is, as shown by aSb and cSd in Fig. 15, in some media, the friction coefficient reaches 1.0 after about 15,000 CsS operations, whereas in some media, the friction coefficient reaches 1.0 even after about 30,000 CsS operations. As can be seen, the time required for the protective film to flatten varies greatly depending on the medium, and the life span varies greatly. As a result, in a large-capacity device equipped with a large number of media, each medium has a different lifespan, so the lifespan of the entire device depends on the media with a short lifespan.
hinders economic efficiency.

A technical object of the present invention is to solve such problems and to make it possible to suppress flattening of the protective film in a textured magnetic recording medium.

[Means to solve the problem]

FIG. 1 is a sectional view illustrating the basic principle of the magnetic recording medium according to the present invention, and is an enlarged view of section A in FIG.

In the case of the present invention, instead of texture processing directly on the flat surface of a non-magnetic substrate as in the past, as shown in FIG. Forming undulations and applying texture processing on top of them, magnetism 1! I3 and a protective film 4 are provided.

[Effect]

FIG. 2 is a cross-sectional view showing the relationship between the core slider 21 of a magnetic head and waviness. The core slider 21 of a normal magnetic head has sight rails 22 and 22 on both sides. A core is provided in the center rail 23 provided between the two, forming a gap for recording/reproducing information.

If you enlarge the part of the undulation 24 where the pitch W of the undulation 24 is smaller than the rail width R of the idle rail 22.22, as shown in FIG. Groove 19
There are 20 texture mountains.

FIG. 1(a) shows the state before the medium is used, and FIG. 1(b) shows the state after it has been used to some extent.

Now, in FIG. 1, when the core slider contacts the medium surface, it contacts only the ridge portions 25 of the undulations and the trough portions 2.
Therefore, when the protective film 4 is worn out due to use, only the protective film 4 at the ridge portions 25 of the undulations is worn out due to contact with the core slider. As shown in FIG. 1(b), the wear powder accumulates in the textured grooves at the ridges 25 of the undulations, and the crests 25 of the undulations gradually become flat, but the troughs 26 of the undulations form the core. Since there is no contact with the slider, the contact area between the medium surface and the core slider is smaller compared to conventional media.

As a result, the coefficient of friction on the medium surface does not increase in a short period of time unlike in the past, and wear resistance is improved, and adhesion of the core slider can be prevented.

〔Example〕

Next, examples will be used to explain how the magnetic recording medium according to the present invention is actually implemented. FIG. 3 is a view of the core slider of a commonly used magnetic head viewed from the medium side. In the example shown, the core slider has a width of 2.5 mm and a length of 4.0 mm. , the width of the Zydrail 22.22 is 250 μm.

In order to stably float the core slider, the pitch W of the undulations formed before the texture treatment should be smaller than the rail width R, as shown in Fig. It is desirable that four or more undulations exist.

Therefore, in the case of a core slider having the dimensions shown in FIG. 3, the pitch W of the undulations of the magnetic recording medium is preferably about 20 to 50 μm.

In addition, the depth of the undulation is determined by the depth of the groove 1 in the texture processing.
A depth of 9 is a good guideline. In other words, if the depth of the undulations is approximately the same as the depth of the grooves 19 in the texture, even if the protective film 4 at the crests 25 of the undulations is worn away and disappears, as shown in FIG. In the portion 26, since the protective film 4 remains uneven due to the texture, the abrasion resistance is maintained.

If the undulations are too shallow than the textured grooves 19, the textured peaks 20 of the protective film at the troughs 26 of the undulations will progress to wear out before the protective film at the crests 25 of the undulations is worn away, and the textured grooves will also wear out. It becomes filled with abrasion powder, etc., and the protective film tends to flatten.

Conversely, if the depth of the undulations is too deep, when the gap of the magnetic head reaches the trough 26 of the undulations, the distance between the magnetic film and the gap is too large, resulting in a decrease in the output during recording/reproduction. This problem exists.

After all, the depth of the undulations is suitable to have a value that is not much different from the depth of the texture grooves, and it is preferable that the undulations be slightly shallower than the maximum depth of the texture grooves. For example, 0
．． Approximately 0.03 to 0.06 μm is suitable.

The formation of undulations can be realized by setting the feed amount of the cutting tool to the pitch W as described above when processing an aluminum substrate with a diamond lathe.

After forming the undulations in this way, it is subjected to alumite treatment or N1-P plating is applied to a depth of about 10 μm, followed by polishing. Thereafter, in a known texture processing apparatus shown in FIG.
Texture is processed using tape, and then a magnetic film and a protective film are layered on top of that. Note that a base film may be formed after the texture treatment.

FIG. 4 is a diagram showing changes in the coefficient of friction between the magnetic recording medium according to the present invention manufactured in this manner and a conventional magnetic recording medium. Even after the operation was repeated 40,000 times, the friction coefficient increased only to about 0.6, confirming that the wear resistance was extremely excellent.

(Effects of the Invention) As described above, according to the present invention, shallow undulations in the radial direction are formed on the surface of the magnetic recording medium and texture processing is performed thereon, so that even if the protective film 4 on the magnetic layer 1113 is worn out, ,
A rapid increase in the contact area with the core slider is suppressed, lubricity is maintained, and prevention of adsorption of the core slider is also maintained.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view explaining the basic principle of the magnetic recording medium according to the present invention, FIG. 2 is a cross-sectional view showing the relationship between the core slider of a magnetic head and waviness, and FIG. 3 is a normally used FIG. 4 is a diagram showing changes in the coefficient of friction between the magnetic recording medium according to the present invention and a conventional magnetic recording medium, and FIG. 5 is a diagram showing III! 6 is a sectional view showing the entire structure of the magnetic recording medium, FIG. 6 is a sectional view showing the layer structure of the thin film magnetic recording medium, FIGS. 7 to 9 are perspective views showing various sputtering methods for the thin film magnetic recording medium, and FIG. Figure 11 is a perspective view showing a non-magnetic substrate texturing device, Figure 12 is a cross-sectional view of a pressure roller, and Figure 13 is a cross-sectional view of a conventional texture processing method. Figure 1 showing
FIG. 4 is an enlarged sectional view showing the state of wear of the protective film in a conventional magnetic recording medium, and FIG. 15 is a diagram showing the relationship between the number of C3S operations of the magnetic head and the friction coefficient of the medium. In the figure, l is a non-magnetic substrate, 2 is a base film, 3 is a magnetic film, 4 is a protective film, 19 is a texture groove, 20 is a texture mountain, 22 is a sight rail, 24 is a undulation, 25 is a undulation mountain, 26 indicates the valley of the undulations, R indicates the rail width of the core slider, and W indicates the pitch of the undulations.

Claims (1)

[Claims] In a thin-film magnetic recording medium in which a magnetic thin film is provided after texturing a non-magnetic substrate, the pitch (W) is narrower than the rail width (R) of a core slider of a magnetic head in advance. A magnetic recording medium in which a magnetic film (3) and a protective film (4) are formed by forming undulations on which a texture treatment is performed.