JPH02223020A - Production of perpendicular magnetic disk - Google Patents

Abstract

PURPOSE:To enhance the magnetic permeability of a soft magnetic layer and to improve recording and reproducing characteristics by providing a conductor in a disk substrate and forming the soft magnetic layer on the disk substrate in the state of generating a magnetic field in the radial direction of the disk substrate. CONSTITUTION:The conductor 14 is interposed between a pair of insulating disks 12 and 13 having apertures 12a, 13a at the center in such a manner that current can be supplied in a circumferential direction to form the disk substrate 11. The soft magnetic layer 22 having the high magnetic permeability is formed by a plating method, vapor deposition method or sputtering method on the disk substrate 11 in the state of generating the magnetic field in the radial direction of the disk substrate 11 by the current passing in the conductor 14. The soft magnetic layer which is imparted with the magnetic anisotropy having the axis of easy magnetization in the radial direction of the disk substrate 11 and is enhanced in the magnetic permeability in the circumferential direction is easily formed. The perpendicular magnetic disk having the excellent recording and reproducing characteristics is obtd. in this way.

Description

[Detailed Description of the Invention] [Summary] This relates to a method for manufacturing a perpendicular magnetic disk suitable for use in a perpendicular magnetic recording type magnetic disk device. A method for manufacturing a perpendicular magnetic disk in which a soft magnetic layer with high permeability is formed on a disk substrate, with the aim of easily forming a soft magnetic layer imparted with anisotropy and increasing the magnetic permeability of the soft magnetic layer. The disk substrate is formed by a pair of insulating disks each having an opening in the center, and a conductor interposed between the two insulating disks to enable current to flow in the circumferential direction of the two insulating disks. A soft material with high magnetic permeability is formed on the disk substrate by plating, vapor deposition, or sputtering, with a current flowing through the conductor in the disk substrate to generate a magnetic field in the radial direction of the disk substrate. The structure is configured to form a magnetic layer.

[Industrial Application Field] The present invention relates to a method for manufacturing a perpendicular magnetic disk suitable for use in a perpendicular magnetic recording type magnetic disk device, and in particular to a method for manufacturing a perpendicular magnetic disk having a double-layer structure with good recording and reproducing characteristics. The present invention relates to a method for forming layers.

Magnetic disks used in magnetic disk devices include:
Horizontal magnetic recording magnetic disks are widely used, in which information is magnetized and recorded in the horizontal direction with respect to the recording tracks in the recording layer, but in recent years, with the increase in the density of information recording, A perpendicular magnetic recording method magnetic disk that uses magnetization in the perpendicular direction was proposed,
A perpendicular magnetic disk having a two-layer structure in which a soft magnetic layer with high magnetic permeability and a perpendicular recording layer are laminated is being put into practical use as a magnetic disk to realize this.

In the soft magnetic layer of this perpendicular magnetic disk, the recording magnetic field from the magnetic head perpendicularly passes through the perpendicular magnetic recording layer and is magnetized, and then passes through the soft magnetic layer and again through the perpendicular magnetic recording layer to the magnetic head side. It plays a part of the function of the magnetic head, which serves as the magnetic field path for returning to the return yoke.
By increasing its magnetic permeability, recording and reproducing efficiency is improved,
There is a need to obtain a perpendicular magnetic disk with excellent recording and reproducing characteristics.

[Conventional technology]

Conventionally, as shown in FIG. 7, the method for manufacturing the perpendicular magnetic disk with the above-mentioned two-layer film structure has been to use a non-magnetic magnetic disk made of, for example, an aluminum (A f ) plate with an alumite surface treatment, or a glass plate. 1μ on the disk substrate l
A soft magnetic layer (also referred to as a soft magnetic backing layer) 2 made of Ni-Fe or the like with a thickness of approximately 0.2 μm thick and a perpendicular magnetic recording layer 3 made of hard magnetic Co-Cr with a thickness of 0.2 μm are continuously sputtered. A protective film 4, a lubricant film 5, etc. are applied to the surface of the perpendicular magnetization recording layer 3 to reduce friction and wear against the magnetic head.

By the way, the magnetic permeability of the soft magnetic layer 2 in the perpendicular magnetic disk obtained by the above manufacturing method is several hundred to 50.
It is extremely low, around 0, and sufficient recording and reproducing characteristics cannot be obtained.
In the method of forming a soft magnetic layer made of Ni-Fe or the like using a sputtering method, it is difficult to increase the magnetic permeability further.

Therefore, focusing on the fact that the magnetic permeability of thin-film magnetic heads made of Ni-Fe can be increased by forming the Ni-Fe magnetic layer by electroplating, attempts have been made to form a soft magnetic layer by electroplating. ing.

However, when the soft magnetic layer is formed by electrolytic plating, its magnetic permeability improves to about 1000, but sufficient recording and reproducing characteristics are still not obtained with this level of magnetic permeability, and the magnetic permeability is increased several times. There was a need to improve even further.

Therefore, as a result of studies to further increase the magnetic permeability of the soft magnetic layer, it was found that the magnetic properties of the soft magnetic layer made of Ni-Fe formed by electrolytic plating are isotropic. If it is possible to form a soft magnetic layer that is magnetically anisotropic so that the magnetic easy axis is directed to
It turned out that it could be increased to more than 500.

[Problem to be solved by the invention]

However, N with magnetic anisotropy as described above
As a method for obtaining a soft magnetic layer made of i-Fe, there are two methods: (1) providing a large number of minute scratches in the radial direction that provide a magnetic easy axis, and forming a soft magnetic layer on the disk substrate surface; (2) forming a soft magnetic layer in the radial direction. A possible method is to form a soft magnetic layer on the surface of the disk substrate while a magnetic field is applied thereto.

However, regarding (2), it is relatively easy to form many scratches etc. in the circumferential direction of the disk substrate surface;
It is extremely difficult to form scratches with uniform depth, pitch, etc. in the radial direction. Regarding (■), it is possible to apply a magnetic field in the radial direction of the substrate surface using a concentric magnet, but in any film formation method, the mechanism for attaching the substrate to the magnet is large-scale, making it difficult to put it into practical use. There were other problems.

In view of the above-mentioned conventional situation, the present invention has been developed to easily form a soft magnetic layer with magnetic anisotropy such that the magnetic easy axis is oriented in the radial direction of the disk substrate, and to increase the magnetic permeability of the soft magnetic layer. The object of the present invention is to provide a method for manufacturing a new magnetic disk with improved recording and reproducing characteristics.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a perpendicular magnetic disk in which a soft magnetic layer with high magnetic permeability is formed on a disk substrate, the method comprising: a pair of insulating disks each having an opening in the center; The disk substrate is formed by a conductor interposed between the two insulating disks and capable of passing a current in the circumferential direction thereof, and a current is passed through the conductor in the disk substrate to cause the disk substrate to be heated. A soft magnetic layer with high magnetic permeability is formed on the disk substrate by plating, vapor deposition, or sputtering while a magnetic field is generated in the radial direction.

[For production]

In the manufacturing method of the present invention, a magnetic field can be generated in the radial direction of the disk substrate by passing a current through the conductor built into the disk substrate. Therefore, by forming a soft magnetic layer made of Ni-Fe or the like by plating, vapor deposition, sputtering, etc. on the disk substrate surface where such a magnetic field is being generated, the radial direction of the disk substrate can be aligned with the magnetic easy axis. A soft magnetic layer having magnetic anisotropy and increased permeability in the circumferential direction can be easily formed. As a result, a perpendicular magnetic disk with excellent recording and reproducing characteristics can be obtained.

The strength H of the magnetic field generated (applied) in the radial direction of the disk substrate should be slightly thicker than the coercive force Hc of the soft magnetic layer to be formed. Controls the current value applied to the

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

1 and 2 are an exploded perspective view and an integrated perspective view showing one embodiment of a disk substrate used in the method of manufacturing a perpendicular magnetic disk according to the present invention.

First, the disk substrate 11 used in the manufacturing method of the present invention has a circular hole 12a at its center, as shown in FIG.

13a, made of glass, ceramic, etc.
For example, a pair of insulating discs 12 with a thickness of about 1lIII
and 13, the insulating disc 12 or 13 has approximately the same shape, is made of copper (Cu), titanium (Ti), etc., and has a thickness of approximately 0.5 mm, and is partially electrically separated. The conductive plate 14 is integrated as shown in FIG. The inner peripheral side of the central circular hole 12a of the insulating disc 12 is connected to the current-carrying terminals 12b and 12c provided on the inner peripheral edge of the surface thereof.

In this embodiment, the disk substrate 11 having such a configuration is used, and as shown in FIG. 4(a), on the disk substrate 11 (
A plating base film 21 made of Ni--Fe and having a thickness of 2000 mm is deposited on the current-carrying terminals 12b and 12c (excluding the portions of the current-carrying terminals 12b and 12c) by sputtering or the like.

Next, as shown in FIG. 3, the energizing terminals 12b and 12C
The disk substrate 11 connected to the current source 35 is attached to the substrate holder 34, and the disk substrate 11 is connected to the current source 35.
SOn ・6HzO) and ferrous sulfate (FeSO4・7H
The plating electrode 33 is placed opposite to a plating electrode 33 in a plating tank 31 filled with a Ni-Fe plating solution 32 whose main component is Ni--Fe plating solution 32.

Then, while a predetermined current is applied to the re-energizing terminals 12b and 12c of the conductive plate 14 to generate a magnetic field in the radial direction of the disk substrate 11, the plating base film (cathode) 21 and the plating electrode (anode) 33 days, for example 4 to 5 days
As shown in FIG. 4(a), a Ni--Fe plating film with a thickness of 3 μm is formed on the base film 21 under the plating conditions of applying a voltage of 6 A/dm and a current density of 6 A/dm. The disk substrate 11 may be rotated as necessary.

In this way, the disk substrate 2 can be formed by forming a film in a magnetic field.
Since magnetic anisotropy is imparted so that the easy axis points in the radial direction of
A soft magnetic layer 22 made of a Ni-Fe plating film having an extremely high magnetic permeability of about c0 can be easily obtained.

Note that the value of the current flowing in the circumferential direction of the conductive plate 14 via the re-energizing terminals 12b and 12c is, for example,
The magnetic field generated in the radial direction of
e) degree or more, the soft magnetic layer 22 formed
The coercive force IIs may be set to be slightly larger than the coercive force IIs.

Therefore, on the soft magnetic layer 22 formed by this method, as shown in FIG.
A perpendicular magnetization recording layer 23 with a thickness of 0.2 μm is formed by sputtering or the like, and a protective film 2 is further formed on its surface.
4 and the lubricating film 25, a perpendicular magnetic disk with excellent recording and reproducing characteristics is completed.

5 and 6 are an exploded perspective view and a magnetized perspective view showing other embodiments of the disk substrate used in the method of manufacturing a perpendicular magnetic disk according to the present invention, and are equivalent to FIGS. 1 and 2. Parts are given the same reference numerals.

The embodiment shown in these figures is different from the examples shown in FIGS. 1 and 2 because it is made of glass or ceramic, for example, with circular holes 12a and 13a in the center.
Between a pair of insulating circles vi12 and 13 with a thickness of about I,
As shown in the figure, they are integrated as shown in FIG. 6 with a spiral conductive coil 42 made of copper (Cu) or the like sandwiched therebetween, and both ends of the conductive coil 42 are connected to the surface of the one insulating disk 12, for example. Current-carrying terminals 43a provided on the outer peripheral edge and the inner peripheral edge
, 43b is used.

Then, similarly to the embodiments shown in FIGS. 3 and 4(a) and (b), a plating base film is formed on the disk substrate 41 (excluding the current-carrying terminals 43a and 43b) by sputtering or the like. After the plating is formed, the plating base film is coated with the current-carrying terminals 43a and 43b of the conductive coil 42 connected to a current source and a predetermined current flowing to generate a magnetic field in the radial direction of the disk substrate 41. By forming an Nt-Fe plating film with a thickness of 3μ by electrolytic plating on the disk substrate 41, magnetic anisotropy can be imparted so that the easy axis is oriented in the radial direction of the disk substrate 41, as in the previous embodiment. 200 in the circumferential direction (recording track direction)
A soft magnetic layer made of a Ni-Fe plated film having an extremely high magnetic permeability of about 0 can be easily obtained.

Therefore, on the soft magnetic layer thus formed, a perpendicular magnetization recording layer made of Co-Cr with a thickness of 0.2 μm is formed by sputtering or the like, as in the conventional example, to further protect the surface. By forming the film and the lubricating film, a perpendicular magnetic disk with excellent recording and reproducing characteristics can be obtained, similar to the embodiments described above.

In addition, in the above embodiment, N with high magnetic permeability was formed by electrolytic plating while a magnetic field was generated in the radial direction of the disk substrate.
An example of forming a soft magnetic layer made of a 1-Fe plating film has been described, but in addition to this electrolytic plating method, vapor deposition method,
Alternatively, Ni can be grown in a similar magnetic field by sputtering.
- Even when a soft magnetic layer made of Fe is formed, it is possible to increase the magnetic permeability to 1500 or more, and it is possible to form a perpendicular magnetic disk with a two-layer structure having such a soft magnetic layer with high magnetic permeability. This improves recording/reproducing efficiency and recording/reproducing characteristics.

〔Effect of the invention〕

As is clear from the above description, according to the method for manufacturing a perpendicular magnetic disk with a double-layer film structure according to the present invention, a soft magnetic layer with high magnetic permeability can be easily formed in the circumferential direction of the disk (recording track direction). It becomes possible to obtain a perpendicular magnetic disk having excellent advantages such as high recording and reproducing efficiency and excellent recording and reproducing characteristics.

Therefore, it is extremely advantageous to apply this method to a method of manufacturing a perpendicular magnetic disk having a double layer structure.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view illustrating an embodiment of a disk substrate used in the method of manufacturing a perpendicular magnetic disk according to the present invention, and FIG. 2 is an integrated configuration of a disk substrate used in the method of manufacturing a perpendicular magnetic disk according to the present invention. FIG. 3 is a cross-sectional view of an apparatus configuration for explaining the method of forming a soft magnetic layer by electrolytic plating according to the present invention, and FIGS. 4(a) and (b) are perpendicular magnetic disks of the present invention. 5 is an exploded perspective view illustrating another embodiment of a disk substrate used in the method for manufacturing a perpendicular magnetic disk according to the present invention; FIG. FIG. 7 is a perspective view showing an integrated configuration of another disk substrate used in the method of manufacturing a perpendicular magnetic disk. FIG. 7 is a sectional view of a main part for explaining the conventional method of manufacturing a perpendicular magnetic disk. Each shows a conductive coil. In Figures 1 to 6, 11.41 is a disk substrate, 12.13 is an insulating disk,
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a43b is a current-carrying terminal, 14 is a conductor, 21 is a plating base film, 22 is a soft magnetic layer, 23 is a perpendicular magnetization recording layer, 24 is a protective film, 25 is a lubricating film, 31 is a plating tank, 32 is a plating solution, 33 is a plating electrode, 34 is a substrate holder, 35 is a current source, 42 is Mefi/lrtM-a-yt=tsChapterLabium#arPyF'xforce)kGntiKt*'A'1li
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Claims (1)

[Claims] High permeability soft magnetic layer (22) on the disk substrate (11)
A method for manufacturing a perpendicular magnetic disk in which: a pair of insulating disks (12, 13) each having an opening (12a, 13a) in the center; A conductor that allows current to flow in the circumferential direction (
14) to form the disk substrate (11), and with a current flowing through the conductor (14) in the disk substrate (11) to generate a magnetic field in the radial direction of the disk substrate (11), A method for manufacturing a perpendicular magnetic disk, characterized in that a soft magnetic layer (22) with high magnetic permeability is formed on the disk substrate (11) by a plating method, a vapor deposition method, or a sputtering method.