JPH02282926A - Magnetic disk - Google Patents

Abstract

PURPOSE:To obtain the magnetic disk having high durability by providing a data area where data is recorded and a landing area which is formed with a thicker protective lubricating layer than in the data area. CONSTITUTION:A substrate which is formed by using glass, Al alloy, etc., applying Ni-P thereon by electroplating and finishing the surface to the specular surface of <=0.005mum average surface roughness Ra is used as a nonmagnetic substrate 4. The data area 2 of this substrate 4 is then coated thereon with Cr at 0.1mum as a nonmagnetic underlying layer 5 and a Co alloy (Co-30at.% Ni) at 0.05mum as a magnetic recording layer 6, respectively by a DC magnetron sputtering method. A deposition preventive plate 8 is installed on front of the nonmagnetic substrate 4 so as to prevent the coating of the landing area 3 with the nonmagnetic underlying layer 5 and the magnetic recording layer 6 and carbon is similarly applied at 0.15mum as the protective lubricating layer 7 on the landing area 3 similarly by the DC magnetron sputtering method and further, the entire part of the disk is coated with the protective lubricating layer consisting of carbon at 0.02mum, by which the magnetic recording medium is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk whose magnetic recording layer is a metal thin film suitable for high-density magnetic recording.

(Prior art) Magnetic disk drives are used in everything from large computers to personal computers as storage devices with excellent storage capacity, access time (the time from receiving an instruction from a host device to starting sending data), and cost. (It has come to be used widely.)

On the other hand, in recent years, the demand for larger capacity and higher density magnetic disks has become stronger due to the increase in the amount of data handled and the trend toward smaller hardware.

In order to achieve this large capacity and high density, various fields are actively considering the practical application of magnetic recording media whose magnetic recording layer is composed of a ferromagnetic metal thin film by plating, vapor deposition, or sputtering, instead of conventional coated media. Some have been commercialized.

In general, magnetic disk drives employ a floating head system in which the head and magnetic recording surface are set in contact at the start of operation, and then the magnetic disk is rotated at high speed, and the head is floated by the airflow generated on the disk surface to maintain the distance. has been done. In this method, the rotation of the magnetic disk stops at the end of the operation, and at this time the head and the magnetic storage surface are in the same frictional state as at the start of the operation.

The frictional force between the head and the magnetic storage body in these contact friction states may wear out the head and the magnetic storage body, and may eventually cause scratches on the head and the magnetic medium.

Further, in a state of contact friction, a slight change in the posture of the head may cause the load applied to the head to become uneven, causing scratches on the head and the surface of the magnetic storage medium. Therefore, various protective films are being considered to prevent these wears.

An example of a magnetic disk on which this protective film is formed is shown in FIG. FIG. 6(a) is its plan view, and FIG. 6(b) is its IV-
It is a sectional view taken along the rV line. In the figure, 32 is a board, and 33 is a data area. This magnetic disk has a nonmagnetic underlayer 35, a magnetic recording layer 36, and a protective lubricant layer 37 laminated in this order on a nonmagnetic substrate 34.

In order to increase the recording density of such media, it is necessary to make the distance between the head and the disk surface as close as possible and to keep it constant.

In other words, in order to achieve high-density recording, it is necessary to configure the area in a region where spacing loss at short wavelengths has a large effect.
It is extremely important to demonstrate the protective function in a thin area.

Therefore, the surface roughness of the magnetic disk and magnetic head is small (
, it is necessary to be smooth.

However, because the disk is smooth, the two stick together when the disk stops rotating, causing problems such as the motor not being able to rotate when starting up, or sudden force being applied during rotation, damaging the disk medium.

As a method to solve this problem,
Publication No. 1919 proposes a magnetic disk that includes a data area for recording data and a landing area whose surface is rougher than the data area.

The purpose of this is to use a less rough data area when recording and reproducing data, and use a more rough landing area when starting and stopping the magnetic disk to reduce the adhesion of the magnetic head and allow the magnetic head to fly stably. That is.

(Problems to be Solved by the Invention) However, the above-mentioned method of forming a protective film or the proposal in Japanese Patent Application Laid-Open No. 60-231919 has the following problems.

In other words, since all magnetic recording media aim for high-density recording, spacing loss is important regardless of the recording method, and there is a limit to the thickness that can be allowed as a protective film, which is 0.03 μm. degree is adopted. However, in order to satisfy durability under a wide range of environmental usage conditions, the thickness is required to be close to 0.1 μm, and the spacing loss is too large, so improvements are desired.

Further, although the above-mentioned proposal can reduce the attraction of the magnetic head by using a landing area with large roughness, it does not improve the durability when repeatedly sliding in contact with the magnetic head.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a magnetic disk which has as little spacing loss between the head and the magnetic layer as possible and has good durability and running performance.

(Means for Solving the Problems) That is, the present invention has (1) a data area for recording data and a landing area on the board surface, and the protective lubricant layer of the landing area is made lower than the protective lubricant layer of the data area. (2) The magnetic disk according to (1) above, wherein the protective lubricant layer in the data area has a thickness of 300 Å or less. be.

(Examples) The present invention will be described in more detail below based on Examples.

FIG. 1(a) is a plan view of a magnetic disk showing an embodiment of the present invention, and FIG. 1(b) is a sectional view taken along line I-1. In the figure, 1 is a board, 2 is a donut-shaped data area, and 3 is a landing area formed concentrically inside the board. The cross section of this data area 2 is shown in figure (b).
As shown in the figure, a nonmagnetic underlayer 5, a magnetic recording layer 6, and a protective lubricant layer 7 are laminated in this order on a nonmagnetic substrate 4. However, in the inner landing area 3, a thick protective lubricant layer 7 is formed directly on the nonmagnetic substrate 4.

Next, a method for manufacturing this magnetic disk will be explained in detail.

The non-magnetic substrate 4 in the present invention shown in FIG. 1 is made of glass, aluminum alloy, or an aluminum substrate coated with N1-P by electroless plating, and its surface has an average surface roughness (Ra) of 0. A mirror-finished material with a thickness of .005 μm or less was used.

This non-6I! By DC magnetron sputtering, chromium was deposited on the data area 2 of the magnetic substrate 4 to a thickness of 0.1 μm as the non-magnetic underlayer 5, and Go gold alloy Co was deposited as the Mi magnetic recording layer.
-30 at% NL) was coated with a thickness of 0.05 μm.

At this time, an adhesion prevention plate 8 was placed in front of the nonmagnetic substrate 4 as shown in FIG. 2 so that the landing area was not covered with the nonmagnetic underlayer 5 and the magnetic recording layer 6 as much as possible.

Similarly, carbon was applied to the landing area 3 as a protective lubricant layer 7 with a thickness of 0.15 μm using the DC magnetron sputtering method in the arrangement shown in FIG.
A magnetic recording medium was obtained by coating with a carbon protective lubricant layer of 0.02 μm.

Next, the purpose is to eliminate the step near the boundary between the data area 2 and the landing area 3, to prevent the head from adhering to the magnetic recording medium, and to remove protrusions on the surface of the magnetic recording medium.
A polishing tape was used to polish disc 1 concentrically.

As a result of subjecting the landing area 3 of the magnetic disk manufactured as described above to a C8S test (contact start/stop test) 100,000 times, no head crash was observed. When a similar test was conducted using the conventional structure shown in FIG. 6, a head crash occurred after 30,000 cycles.

This confirmed that the magnetic disk of the present invention had excellent durability. Furthermore, since the magnetic disk starts and stops in the landing area 3 covered with a sufficiently thick protective lubricant layer 7, the protective lubricant layer 7 of the entire disk 1 can be made even thinner, reducing spacing loss. This structure is expected to be suitable for high density.

In the above example, carbon was used as the protective lubricant layer, but it is not limited to this.
2, Sis N4, etc. can also be preferably used.

There is no limit to the thickness of the protective lubricant layer in the data area, but the spacing loss should be kept as small as possible (3.
It is more preferable that the thickness is 00 Å or less.

The nonmagnetic underlayer 5, magnetic recording layer 6, and protective lubricant layer 7 can also be manufactured by vapor deposition in the same manner as described above. However, when covering the nonmagnetic underlayer 5 and the magnetic recording layer 6 with plating (mainly electroless plating), it is necessary to mask the landing area 3 portion of the nonmagnetic substrate 4.

Further, the landing area may be provided on the outer periphery of the board. Furthermore, the nonmagnetic underlayer may be applied over the entire surface of the nonmagnetic substrate. In this case, the protective lubricant layer in the landing area becomes thinner accordingly. The protective lubricating layer may also be applied by plasma polymerization. Additionally, if lubricating oil is used in combination, durability will be further improved.

4 and 5 show other embodiments of the invention. In FIG. 4, 18 is a disk, 19 is a data area, 20 is a landing area, 21 is a nonmagnetic substrate, 22 is a nonmagnetic underlayer, 23 is a magnetic recording layer, and 24 is a protective lubricant layer. In this example, as shown in the figure, a non-magnetic Jt! ! This is an example in which the layer 22 and the magnetic recording layer 23 are included.

In addition, in Fig. 5, 25 is a board, 26 is a data area,
27 is a landing area, 28 is a nonmagnetic substrate, 29 is a nonmagnetic underlayer, 30 is a magnetic recording layer, and 31 is a protective lubricant layer. As shown in the figure, a structure may be adopted in which only the protective lubricant layer 31 is gradually thickened in the landing area. However, in this case, if the thickness is increased so that a≦o, ooio, as shown in the enlarged view (c) of the portion A in FIG. 5(b), there will be no problem in running the head.

(Effects of the Invention) As described above, according to the present invention, by providing a data area for recording data and a landing area with a thicker protective lubricant layer than this data area, high durability can be obtained. This has the remarkable effect of increasing the lifespan and reliability of magnetic disks. Furthermore, spacing loss can be minimized and high-density recording can be achieved.

[Brief explanation of drawings]

1(a) and 1(b) are a plan view and a sectional view taken along the line I-1 of a magnetic disk according to an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of the manufacturing method thereof, and FIG. 4(a) , (b) and Figure 5 (a)
), (b) are a top view, a cross-sectional view taken along the line ■-■, a cross-sectional view taken along the line ■-1ll, FIG. 5(C) is an enlarged view of part A, and FIG. 6(a) is a top view of another embodiment of the present invention. , (b) are a plan view and a sectional view taken along the line IV--IV of a conventional magnetic disk. Explanation of symbols 1.18, 25.32... Board 219.2 3, 20. 2 4, 21. 2 522.2 6, 23. 3 7, 24. 3 8...Adhesion prevention plate 9...Targeter α...Angle A...Enlarged part 6.33...Data area 7...Landing area 8.34...Nonmagnetic substrate 9.35 ...Nonmagnetic underlayer, 0.36...Magnetic recording layer l, 37...Protective lubricant layer Figure 1, Figure 4 (a) 19 Data area, Figure 2, Figure 3, Figure 5 (a) ) (b) α≦0.001 Figure 6 (a)

Claims (2)

[Claims] (1) A magnetic disk characterized in that it has a data area for recording data and a landing area on its disk surface, and the protective lubricant layer in the landing area is thicker than the protective lubricant layer in the data area. (2) The magnetic disk according to claim 1, wherein the thickness of the protective lubricant layer in the data area is 300 Å or less.