JPS6250884B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage body used in a magnetic storage device such as a magnetic disk device or a magnetic drum device, and a method for manufacturing the same.

In general, there are the following methods for recording and reproducing a magnetic storage device comprising a recording and reproducing magnetic head (hereinafter referred to as a head) and a magnetic storage body. That is, after the head and the magnetic storage surface are set in contact at the start of operation, a space corresponding to an air layer is created between the head and the magnetic storage surface by giving the magnetic storage the required rotation, and this This is a method of recording and reproducing in the current state (contact start-stop method, hereinafter referred to as the CSS method). In this method, the rotation of the magnetic storage body stops at the end of the operation, and at this time the head and the surface of the magnetic storage body are in the same frictional state as at the beginning of the operation.

The frictional force generated between the head and the magnetic storage material under these contact friction conditions may wear out the head and the magnetic storage material, and may eventually cause scratches on the head and the metal magnetic thin film medium. Further, in the contact friction state, a slight change in the posture of the head may cause the load on the head to become uneven, causing scratches on the surface of the head and the magnetic storage body.

Furthermore, during recording and reproducing, the head suddenly comes into contact with the magnetic storage body, and a large frictional force acts between the head and the magnetic storage body, often resulting in destruction of the head and the magnetic storage body. In order to protect the head and the magnetic memory from such contact friction, contact wear and contact breakage between the head and the magnetic memory, it is necessary to coat the surface of the magnetic memory with a protective film.

Various protective films have been proposed in the past, and polysilicic acid, which has high hardness and is easy to mass-produce, has already been proposed as a protective film that is effective against contact friction, contact wear, and contact breakage (Japanese Patent Application Laid-Open No. (See Publication No. 52-20804.) Although this also protects the magnetic memory against phenomena such as the contact friction, the higher the reliability with respect to such phenomena as the contact friction, the more desirable it is, and improvements in reliability are always desired. .

An object of the present invention is to provide a magnetic memory body having a protective film that better protects a metal magnetic thin film medium against phenomena such as the above-mentioned contact friction, and which is excellent in mass production, and a method for manufacturing the same.

That is, the magnetic memory of the present invention is a magnetic memory having a reflective layer coated on a metal magnetic medium and polysilicate coated on the reflective layer, and the manufacturing method of the present invention is a magnetic memory having a reflective layer coated on a metal magnetic medium, and the manufacturing method of the present invention is a magnetic memory having a metal magnetic medium coated with a reflective layer and polysilicate coated on the reflective layer. It is characterized by selectively firing polysilicic acid by irradiating it with light.

Next, the present invention will be explained in detail with reference to the drawings.
The figure is a cross-sectional view of the magnetic storage body.

In the figure, aluminum alloy is most often used as the base 1 of the magnetic memory body because it is light, easy to work with, and inexpensive, but titanium alloy may be used in some cases. The base surface is machined to create small waviness (less than 50μm in the circumferential direction and radial direction).
100μm or less).

Next, a nickel-phosphorus alloy is coated on this base 1 as a base body 2 by plating, and this base body 2
The surface has a surface roughness of 0.03μm by mechanical polishing.
Mirror finish is achieved below (Rmax).

Next, a cobalt-nickel-phosphorus alloy is coated as a metal magnetic medium on the mirror-polished surface of the base body 2 by plating, and a reflective layer 4 is coated on the metal magnetic medium 3. The reflective layer 4 is provided to prevent the metal magnetic medium 3 from absorbing laser light and being heated, and when a carbon dioxide laser is used as a light source, silver, gold, or copper, which has a high reflectance at a wavelength of around 10.6 μm, is used. preferable. It is desirable that the film thickness is such that it has little effect on the thickness of the protective film (500 Å or less).

Next, polysilicic acid as disclosed in Japanese Patent Application Laid-Open No. 52-20804 cited above is coated on this reflective layer 4 as a protective film 4 by a spin coating method. Next, the surface of the magnetic memory body coated with this polysilicate was coated with a wavelength of 9 μm.
The polysilicate film is baked and hardened by irradiation with carbon dioxide laser light of ~11 μm.

Polysilicic acid has a large absorption of light in the wavelength range of 4 μm to 50 μm, and according to the infrared absorption spectrum, it has a particularly large absorption in the 9 to 10 μm range;
It can be seen that carbon dioxide laser of ~11 μm is well absorbed.

The magnetic storage body having a reflective layer according to the present invention has excellent abrasion resistance against heads and is easily produced in large quantities.When a high-energy-density laser beam is used as a baking hardening method for polysilicic acid, it is possible to form a cobalt-nickel-phosphorus alloy. Also, it is possible to prevent the temperature rise of the nickel-phosphorus alloy that is the base metal.

That is, due to the higher energy density of laser light, the laser light absorption characteristics of polysilicate, and the high laser light reflectance of the reflective layer 4, a high temperature gradient is created between polysilicate and cobalt-nickel-phosphorus alloy or nickel-phosphorus alloy. occurs, and at the same time as curing the polysilicic acid, magnetization of the base body or deterioration of the magnetic properties of the metal magnetic medium can be prevented, and mass productivity can be increased by shortening the irradiation time.

Next, the method for manufacturing a magnetic memory of the present invention will be explained in detail using Examples and Comparative Examples.

Example 1 As the substrate 1, the base body 2 was placed on a disk-shaped aluminum alloy disk whose surface was finished with sufficiently small waviness (50 μm or less in the circumferential direction and 10 μm or less in the radial direction) by lathe processing and heat straightening. Nickel-phosphorus alloy is plated to a thickness of approximately 50μm, and this nickel-phosphorus plating film has a surface roughness of 0.02μm.
(Rmax) Mirror polished to a thickness of 30μm.

Next, on this nickel-phosphorus plating film, a cobalt-nickel-phosphorus alloy with a thickness of 0.05 μm was applied as a magnetic medium 3.
I was impressed by the thickness. This cobalt - nickel -
Silver was plated to a thickness of 0.05 μm as a reflective layer on the phosphor-plated film, and 0.1% of a 2% n-butyl alcohol solution of tetrahydroxysilane was applied on the reflective layer.
It was applied to a thickness of μm, dried, and then baked at 200°C for 1 hour to form a polysilicic acid protective film.

Next, a magnetic disk was created by irradiating and baking the polysilicate film with a pulsed carbon dioxide gas laser with an output of 25 kW, focused to a spot diameter of 0.7 mm.

Example 2 A magnetic disk was produced in the same manner as in Example 1, except that the reflective layer was coated with gold plating to a thickness of 0.05 μm instead of silver.

Example 3 A magnetic disk was produced in the same manner as in Example 1, except that copper was coated with a thickness of 0.05 μm instead of silver as a reflective layer by plating.

Comparative Example A magnetic disk was made in the same manner as in Example 1, except that it was not coated with a reflective layer.

When the magnetic properties of the magnetic disks shown in Examples 1 to 3 and Comparative Example were measured before and after laser irradiation, it was found that the magnetic disk of Comparative Example showed a 5% increase in the coercive force (Hc) of the metal magnetic medium, and a lower The magnetic flux density (Br) of nickel-phosphorus in the geological formations occurred at 100 Gauss, but there was a slight change in the magnetic disks of Examples 1 to 3.

Note that in all Examples 1 to 3, the CSS test was repeated 30,000 times, but no scratches occurred.

Regarding mass production, in the case of Examples 1 to 3, the diameter
In the case of a 14-inch magnetic disk, the processing time was several minutes per side, but in the case of the comparative example, it took more than 10 minutes.

From the above, the magnetic storage body of the present invention and the magnetic disk manufactured by the manufacturing method thereof are free from changes in the magnetic properties of the metal magnetic medium and magnetization of the underlayer, and are superior in reliability and mass production. I found out.

[Brief explanation of the drawing]

The figure is a partial sectional view showing an embodiment of the magnetic storage body of the present invention. In the figure, 1 is a base, 2 is an underlayer, 3 is a magnetic medium, 4 is a reflective layer, and 5 is a polysilicate layer.

Claims (1)

[Claims] 1. A magnetic medium is coated on a mirror-polished base body, a reflective layer is coated on the medium, and a polysilicic acid is coated on the reflective layer. magnetic memory. 2. The magnetic memory according to claim 1, wherein the reflective layer is made of Ag, Au, or Cu. 3 A magnetic medium is coated on a mirror-polished base body, a reflective layer is coated on the medium, a polysilicic acid is coated on the reflective layer, and then the polysilicic acid is irradiated with a laser beam. A method for manufacturing a magnetic memory, which comprises firing. 4. The method for manufacturing a magnetic memory body according to claim 3, wherein the reflective layer is made of Ag, Au or Cu.