JPS62256216A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To form ruggedness on the surface of the protective layer of a landing zone by providing a ruggedness forming layer between the magnetic layer and protective layer of said zone and forming said layer so as to have the surface roughness larger than the surface roughness of the magnetic layer. CONSTITUTION:An underlying layer 12, the magnetic layer 13 and a surface layer 15 are laminated on the base 11 consisting of glass or ceramics and the ruggedness forming layer 14 consisting of Al, etc., is formed on the layer 13 of the landing zone 10b. The layer 14 is formed to have the surface roughness larger than the surface roughness of the layer 13 and therefore, the zone 10b of the layer 15 has the surface roughness layer than that of a read-write zone 10a surface roughness. since the coefft. of friction of the zone 10b of the layer 15 is thereby maintained small, the good starting is assured for a long period of time. High-density recording is possible as the surface roughness of the zone 10a of the layer 15 is maintained small.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium used in a magnetic recording device, and in particular, to a magnetic recording medium for smooth startup of the magnetic recording medium. Regarding the medium.

[Conventional technology]

As a magnetic recording medium, there is one shown in FIG. This disc-shaped magnetic recording medium 1 has a read/write zone 1a in which various information is mainly written or read by a magnetic head, and a diametrically inner side of this read/write zone 1a in which information is mainly written or read. It is divided into a landing zone 1b where the magnetic head is placed after reading is completed. Note that a through hole 1C having a circular cross section is formed in the center of the magnetic recording medium 1, into which a rotating shaft for rotating the magnetic recording medium 1 is inserted. And conventionally,
The structure of this magnetic recording medium 1 is disclosed in Japanese Patent Application Laid-Open No. 61-332.
As described in Publication No. 2, there was one shown in FIG. In other words, A! A non-magnetic support 4 (hereinafter referred to as "support") consisting of a substrate 2 and a nickel base plating layer 3.

) and a magnetic plating layer 5 (film thickness 5, 0.2 μm or less) on the cobal 1. This nickel base plating layer 3 has a large surface roughness required for the landing zone 1b on its entire surface, and then has a small surface roughness only in the read/write zone 1a. Polish and finish.

Nickel underplating FytJa with such a surface
Similarly to the surface of the nickel base plating layer 3, the surface of the upper cobalt magnetic plating layer 5 has a larger surface roughness in the landing zone 1b than in the read/write zone la.

The reason why the surface roughness of the above-mentioned landing zone 1b is made larger than that of the read/write zone 1a is due to the phenomenon that the magnetic head is attracted to the landing zone when the magnetic head is placed in the landing zone 1b, that is, the magnetic recording medium. This is to prevent phenomena that would make it impossible to rotate or make it difficult to rotate.

[Problem that the invention seeks to solve]

However, in magnetic recording media of conventional structure, the surface of the nickel base plating layer constituting the support is made to have different surface roughnesses required for each of the read/write zone and the landing zone. It was extremely difficult to divide the surface into a read/write zone and a landing zone and polish the read/write zone to a surface roughness suitable for high-density recording. That is, conventional magnetic recording media have problems when used for high-density recording.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and is characterized by a magnetic recording medium in which a magnetic layer is interposed between a support and a protective layer. A roughening layer for forming roughness on the surface of the retention layer of the landing zone is provided between the magnetic layer and the protective layer of the landing zone, and a roughening layer of the roughening layer is provided. The surface roughness of the magnetic layer is greater than the surface roughness of the magnetic layer.

A desirable aspect of the present invention is that the unevenness forming layer and the protective layer are sequentially laminated on the magnetic layer, that the unevenness forming layer is provided only in the landing zone, and that the surface roughness of the magnetic layer is Rlax,
The odor is 150 Å or less, or the support is made of glass or ceramic.

〔Example〕

A first embodiment of the present invention will be described in detail below based on FIG. 1, and a second embodiment will be explained in detail below based on FIG. 2.

[Example 1] The magnetic recording medium 10 of this example will be explained based on FIG. Note that this figure is a partially enlarged schematic cross-sectional view. moreover,
The magnetic recording medium 1o of this example has a shape as shown in FIG. 4, and a read/write zone 10a and a landing zone 10.
b.

The magnetic recording medium 10 shown in FIG. 1 has a support 11 made of soda lime glass (diameter: 1301 mm.thickness: 1 mm.
The base layer 12 (thickness: 2000 nm) is made of chromium (Cr), which has a function of improving the magnetic properties, and has a diameter of the central through hole: 40 mm.
A magnetic layer 13 consisting of nickel (CO) and nickel (N1) (the respective contents are 75 wt% and 25 wt%, and the film thickness is 700%) and the magnetic layer 13 deposited on the landing zone 10b of the magnetic layer 13 , an unevenness forming layer 14 (WA thickness: 250 layers) made of a 1 m film of aluminum (A4), and a protective layer 15 (thickness: 500 layers) made of a carbon (C) thin film. The surface roughness of the main surface of the support 11 is RWAax, which is measured by 40 people (hereinafter, the surface roughness is Rl
Indicated by ax. ), the surface roughness of the magnetic film 13 is 50 mm, the surface roughness of the unevenness forming layer 14 is 110 mm, and the surface roughness of the landing zone 10b and read/write zone 10a of the protective layer 15 is 110 mm and 50 mm, respectively. . In addition, in FIG. 1, the sawtooth shape of the surface roughness of the support 11 is shown only on the main surface on the side where the protection A15 etc. is provided, and the sawtooth shape on the opposing main surface is omitted (the same applies to FIG. 2, which will be described later).
. Further, the sawtooth shapes of each layer 12, 13, 14, 15 and the support 11 are schematically shown (the same applies to FIG. 2, which will be described later).

Next, a method for manufacturing the magnetic recording medium 10 of this example will be described. First, the base layer 12 was formed on the main surface of the support 11 by sputtering using a target made of Cr.

Next, on this underlayer 12, a magnetic layer 13 is formed of Co and Ni.
The film was formed by sputtering using a target consisting of. Next, an unevenness forming layer 14 was formed by a sputtering method using a spacing as a sputtering target through a mask that covered only read dry 1 to zone 10a of the magnetic layer 13.

Note that in this film formation, the temperature of the support 11 was set to 200°C.
Therefore, it becomes a thin film with developed grain boundaries,
Desired unevenness on the protective layer 15 of the landing zone 10b,
In other words, surface roughness can be formed. Further, the read/write zone 10 of the unevenness forming layer 14 and the magnetic layer 13
A protective layer 15 was formed on a by sputtering using a target made of carbon. Note that in the protective layer 15, there is a level difference of about 250 people between the read/write zone 10a and the landing zone 10b, but this is about 1/10 of the flight height of the magnetic head, so The level difference does not pose any problem for movement.

In the magnetic recording medium 10 of this example, the surface roughness of the magnetic layer 13 is made smaller than the surface roughness of the unevenness forming layer 14, so the surface roughness of the protective layer 15 in the landing zone 10b is The desired surface roughness is obtained under the influence of the surface roughness of No. 14. Further, since the unevenness forming layer 14 is formed on the magnetic layer 13, the read/write zone 10a of the magnetic layer 13 is
It can be maintained well without affecting the surface roughness of the surface, and as a result, high-density recording is possible.

In order to evaluate the performance of the magnetic recording medium 10 of this example, the following measurements of the coefficient of static friction between the magnetic head and the magnetic recording medium 10 and the durability test were conducted.

When a load of 15 grams is applied to the magnetic head, a contact start/stop test of the landing zone 10b (starting and stopping the rotation of the magnetic recording medium with the magnetic head in contact with the surface of the magnetic recording medium and keeping it stationary) is performed. (hereinafter referred to as 1-C8S test). The initial coefficient of static friction in this test was 0.15 and 1
The coefficient of static friction after 5000 CSS tests was also 0.7, and the magnetic head did not cause the magnetic recording medium 10 to become unable to rotate or become difficult to rotate. No damage occurred. On the other hand, for comparison, the read/write zone 10a (the surface roughness of the read/write zone 10a of the protective layer 15 is 50).

), when a similar C8S test was conducted, the initial coefficient of static friction was 0.2, but after 15,000 tests, it became 2.5 or more, making it difficult for the magnetic recording medium 10 to rotate, and the magnetic In order to rotate the recording medium 10, a starting torque larger than necessary must be applied to the rotation source,
It is no longer possible to maintain normal rotation.

Furthermore, in this example, since the landing zone of the magnetic layer is covered with the unevenness forming layer, it is possible to prevent head crushing of the magnetic layer by the magnetic head, that is, to prevent mechanical impact on the magnetic layer. This has the effect of improving the moisture resistance of the magnetic layer.

(Example 2) The magnetic recording medium 20 of this example will be explained based on FIG. 2. The figure is a partially enlarged schematic cross-sectional view, and the magnetic recording medium 20 of this example has the same shape as that of the previous example, and has a read/write zone 20a and a landing zone 20b.

The magnetic recording medium 20 of this example includes a support 21 similar to the above embodiment, an underlayer 22 and a magnetic layer 23 similar to the above embodiment.
, an unevenness forming layer 24 (thickness: 200 layers) consisting of eight resins, which is adhered not only to the landing zone 20b of the magnetic layer 23 but also to the read/write zone 20a, and the protective layer 25 ( However, the film thickness is 300 people.)
It consists of The surface roughness of the main surface of the support 21, the surface roughness of the magnetic layer 23, the surface roughness of the unevenness forming layer 24, and the surface roughness of the protective layer 25 are 40, 50, 100, and 100, respectively. It's a person. That is, the surface roughness of the read/write zone 20a and the landing zone 20b of the protective layer 25 is 100, respectively.

Next, a method of manufacturing this magnetic recording medium 20 will be described.

First, the underlayer 22 and the magnetic layer 23 are sequentially formed on the main surface of the support 21 in the same manner as in the above embodiment, and then ^
The unevenness forming ff124 was formed on the read/write zone 20a and the landing zone 20b of the magnetic layer 23 by sputtering using a stand-up target. In addition, in this film formation, the temperature of the support body 21 was set to 180° C. in order to obtain the above-mentioned surface roughness of 100. Furthermore, a protective layer 25 is formed in the same manner as in the previous embodiment.

According to this example, since the surface roughness of the unevenness forming layer 24 is greater than the surface roughness of the magnetic layer 23, the landing zone 20
The roughness of the protective layer 250 (b) is influenced by the surface roughness of the unevenness forming layer 24 and has a desired surface roughness.

Note that in this example as well, the surface roughness of the magnetic layer 23 can be maintained because the unevenness forming layer 24 is already formed on the magnetic layer 23 as in the previous example. Further, in this example, the surface roughness of read dry 1 to zone 20a of the protective layer 25 is 100, but the surface roughness of the magnetic layer 23 is 50.
Since it can be maintained by a person, it is possible to maintain high-density recording performance in read/write zones 1 to 20a, and as will be described later, it is also possible to maintain the high-density recording properties of the read/write zone 1 to zone 20a, and as will be described later, the landing zone 20b is also inconvenient due to adsorption with the magnetic head, that is, when the magnetic recording medium 20 rotates. does not occur.

Further, in the landing zone 20b, as a result of conducting a test similar to the above example, the static friction coefficient at the initial stage of the test was 0.17, and the static friction coefficient after 15000 times CSS test was 0.9, and the above example 15 compared to Nodoki
Although the coefficient of static friction increased after 000 tests, no phenomenon occurred in which the magnetic recording medium 20 became unable to rotate or became difficult to rotate. There was no damage to the magnetic recording medium 20 or the magnetic head.

Furthermore, similar to the embodiment described above, there is an effect of preventing head collision on the landing zone 20b of the magnetic layer 23 and an effect of improving moisture resistance, and the unevenness forming layer 24 is also adhered to the read/write zone 20a of the magnetic layer 23. Therefore, the read/write zone 20a of this magnetic layer 23
has a similar effect.

In this example, the surface roughness of the unevenness forming layer 24 that is effective for both the landing zone 20b and the reedry 1 to zone 20a is 60 to 150, and the surface roughness of the surface roughness in this range is 60 to 150. In 20b, it is possible to prevent the magnetic head from being attracted, and on the other hand, it is possible to sufficiently cope with the increase in the density of the read/write zone 20a.

The present invention is not limited to the above-described embodiments, but may include the following embodiments. First, the material of the support is not limited to glass such as soda lime glass, aluminosilicate glass, quartz glass, etc.
It may be an A1 alloy or a ceramic. Preferably,
Glass and ceramic are preferred because they are easier to process to the desired surface roughness than A1 alloy, and have very few bits or protrusions on the main surface that adversely affect high-density recording.

Further, the surface roughness of the support is preferably 150 Å or less.

In other words, the surface roughness of the support affects the surface roughness of the underlayer and the magnetic layer, so if the surface roughness of the support exceeds 150, the surface roughness of the magnetic layer also exceeds 150. Therefore, when performing high-density recording by lowering the flying height of the magnetic head, recording defects such as missing (signals to be recorded are not reliably recorded) may occur. In other words, high density recording may sometimes be impaired. Further, in the above examples, the temperature of the support when forming the unevenness forming layer made of An was 200°C or 180°C, but the temperature is not limited to this, and other temperatures, that is, the temperature of the protective layer of the landing zone, may be used. It is sufficient if the temperature is such that the surface roughness of the unevenness forming layer is such that the surface roughness is J: which produces an effect of preventing adsorption to the magnetic head. Desirably, the temperature is 100° C. or higher, at which the development of the grain boundaries of AI is remarkable, that is, the surface roughness increases, and the temperature is preferably 300° C. or lower, for practical purposes. Note that the temperature of the support and the unevenness forming layer (thickness: 20
Figure 3 shows the relationship with the surface roughness of 0 persons). Although the unevenness forming layer is made of a thin film, it may be made of other films, preferably a crystalline thin film in which grain boundaries develop, such as Sn, In, Pb, In, Sb, etc. metal,
A thin film made of an alloy containing one of these or an oxide or nitride of these, or a dielectric film such as Zro2, Hg F2 or -14=ZnS is preferable. Further, the thickness of the unevenness forming layer is preferably 100 Å or more and 1500 Å or less.

In other words, if the film thickness is less than 100, it will be difficult to produce a roughness forming layer having the desired surface roughness, that is, a surface roughness of 60 Å or more that has a remarkable effect of preventing the magnetic head from adhering to the landing zone. If it exceeds this, the distance between the magnetic layer and the magnetic head becomes large during the operation of the magnetic recording medium shown in Example 2, and information writing and reading characteristics may deteriorate. Incidentally, a similar situation may occur when writing information into the landing zone of the magnetic recording medium of the first embodiment. In addition, as mentioned above, it is desirable that the surface roughness of the unevenness forming layer is 60 Å or more, but the upper limit is as long as the surface roughness forms the surface roughness of the protective layer that allows the magnetic head to fly stably. good. but,
Desirably, the thickness is 1000 Å or less, which is sufficient for high density. Next, the underlayer may be made of a nonmagnetic material such as No, Ti, Ta, or the like. Note that although this underlayer may be omitted, it is preferable to provide it in order to improve magnetic properties. In addition, the magnetic layer is not limited to one made of CoNi alloy, but may also be made of CO as a main component, such as UNi, Fe, Pt,
It may be made of an alloy containing at least one element among P, Cr, W, Ho, etc., or Fe2O3, as long as it can obtain predetermined magnetic properties. The protective layer may be a composite layer, for example, a layer in which a Cr layer and a 0 layer are in contact with each other, a layer in which a Cr layer and a Si 02 layer are in contact with each other, a layer in which a Cr layer and a Si 0 layer are in contact with each other,
It may be a layer consisting of an r layer, an 0 layer, and a Si 02 layer, which are laminated in proper contact with each other, or a mixed layer obtained by mixing the materials of the composite layer, and further made of an St 02 layer or an organic polymer. It may be. Further, in order to enable high-density recording, the surface roughness of the magnetic layer is preferably 150 Å or less. Further, the thickness of the protective layer is desirably a value such that the total thickness of the protective layer and the thickness of the unevenness forming layer is 1500 Å or less. That is, when the total thickness of the protective layer and the unevenness forming layer exceeds 1,500 layers, the same problem as described above when the thickness of the unevenness forming layer exceeds 1,500 layers may occur. Further, the thicknesses of the underlayer and the magnetic layer may be determined as appropriate, respectively, as necessary. Additionally, the landing zone may be provided radially outward or in the middle. Furthermore, the method for forming the underlayer, magnetic layer, unevenness forming layer, and protective layer is not limited to the sputtering method, but may be a vacuum evaporation method or an ion plating method.

〔Effect of the invention〕

According to the magnetic recording medium of the present invention, smooth startup of the magnetic recording medium can be performed, and rough high-density recording has become possible.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention, and FIG. 2 is a partially enlarged schematic cross-sectional view showing another embodiment of the present invention. Figure 3 shows the temperature of the support and the Al
FIG. 3 is a characteristic diagram showing the relationship between the surface roughness of the unevenness forming layer and the surface roughness. FIG. 4 is a schematic plan view showing a general magnetic recording medium, and FIG. 5 is a partial cross-sectional view of the conventional magnetic recording medium. 10, 20...magnetic recording medium, 10a, 20a...
Read/write zone, 10b, 20b... Foot T inog zone, 11.21... Support, 12.22...
Base layer, 13.23... Magnetic layer, 14.24... Irregularity forming layer, 15.25... Protective layer.
-＼ ＼Figure 3Figure 4

Claims (5)

[Claims] (1) In a magnetic recording medium in which a magnetic layer is interposed between a nonmagnetic support and a protective layer, a landing zone is provided in the magnetic recording medium, and a landing zone is provided between the magnetic layer and the protective layer. providing an unevenness forming layer for forming unevenness on the surface of the protective layer of the landing zone;
A magnetic recording medium characterized in that the surface roughness of the unevenness forming layer is greater than the surface roughness of the magnetic layer. (2) The magnetic recording medium according to claim (1), characterized in that an unevenness forming layer and a protective layer are sequentially laminated on the magnetic layer. (3) Claim (1) or (2) characterized in that the unevenness forming layer is provided only in the landing zone.
Magnetic recording medium described in Section 1. (4) The surface roughness of the magnetic layer is Rmax. 150 Å at
A magnetic recording medium according to claim (1), (2) or (3), characterized in that: (5) A magnetic recording medium according to claim (1), (2), (3), or (4), wherein the nonmagnetic support is made of glass or ceramic. .