JPS6226096B2 - - Google Patents

Description

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

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 CSS method). In this method, at the end of the operation, the magnetic storage body stops rotating, and at this time the head and the magnetic storage body surface are in a frictional state of contact, 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, coating 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. 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 method for manufacturing a magnetic memory body that has a protective film that better protects a metal magnetic thin film medium against phenomena such as the above-mentioned contact friction and is excellent in mass production.

That is, the method for manufacturing a magnetic memory according to the present invention is characterized in that polysilicate coated on a metal magnetic medium is irradiated with laser light using a focuser and fired.

Next, the present invention will be explained in detail with reference to the drawings.

FIGS. 1 and 2 are cross-sectional views of a magnetic memory and a focusing device.

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 surface of the base is machined to create small undulations (less than 50 μm in the circumferential direction and in the 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 on the mirror-polished surface of the base body 2 as a metal magnetic medium 3 by plating, and a protective film 4 is formed on the metal magnetic medium 3 in Japanese Patent Application Laid-Open No. 52-20804 cited earlier. The polysilicic acid 4 shown in No. 1 is coated by a spin coating method.
Next, the surface of the magnetic memory body coated with this polysilicate film 4 is irradiated with carbon dioxide laser light having a wavelength of 9 μm to 11 μm to harden the polysilicate film 4 by firing.

The laser beam irradiation methods shown in FIGS. 1 and 2 are two examples of the present invention.

In the case of FIG. 1, the laser beam 6 is condensed by a convex lens 7 and irradiated onto one focal point F of a condenser 5 made of a spheroidal mirror. At this time, the laser beam is absorbed by the polysilicate film 4 and The silicic acid film 4 is fired and hardened.

The laser light that is not absorbed by the polysilicate film is reflected by the metal magnetic medium 3, further reflected on the inner surface of the condenser, and then further reflected on the inner surface of the condenser through another focal point F' of the condenser 5. After being reflected, the light is focused again on the focal point F, and the polysilicate film 4 is fired and hardened.

The greater the number of reflections by the condenser, the higher the absorption energy density of the laser beam. You can increase it by tilting it. The inclination angle is preferably about the same as the convergence angle of the convergent laser beam.

Further, the condenser can also have both focal points of the spheroidal mirror placed on the surface of the metal magnetic medium as shown in FIG. In this case, the number of reflections is halved compared to the method in which one focal point is placed on the surface of the metal magnetic medium, but the polysilicate film can be fired at two locations at the same time.
In the case of this configuration, the laser beam that is not absorbed by the polysilicate film at one focus is reflected and the polysilicate film is fired and hardened at the other focus.

In either case of Fig. 1 or Fig. 2, when baking and hardening the protective film over a wide area of the magnetic storage body, the area to be baked and hardened is adjusted by rotating the magnetic storage body in the in-plane direction. You can move in sequence.

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

In addition to thermal curing of polysilicic acid by absorption of laser light as described above, the method of firing polysilicic acid using carbon dioxide laser light is also used to magnetize the nickel-phosphorus alloy used as the base body 2 or to use it as the metal magnetic medium 3. One of the excellent features is that the magnetic properties of the cobalt-nickel-phosphorus alloy produced are not impaired, but the higher the energy density of the laser beam, the more remarkable the above effect becomes. That is, it is possible to increase the temperature gradient between the polysilicate film and the metal magnetic medium or the base body, increase the firing temperature of the polysilicate film, and shorten the firing time. In other words, by increasing the absorption energy density of laser light (the energy density of laser light absorbed by polysilicate) using the condenser shown in the present invention, there is no magnetization of the substrate or deterioration of the magnetic properties of the metal magnetic medium. It is possible to form a polysilicate film that is harder and has excellent resistance to contact friction with the head.

Next, the method for manufacturing the magnetic storage body of the present invention will be explained in detail with reference to Examples and Comparative Examples.

Example 1 As the substrate 1, a disc-shaped aluminum alloy plate 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 machining and thermal straightening was used as the base body 2. The nickel-phosphorus alloy is plated to a thickness of about 50 μm, and the nickel-phosphorus plating film has a surface roughness of 0.02 μm.
(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 coated as a magnetic medium 3.
I was impressed by the thickness. This cobalt - nickel -
2% of tetrahydroxysilane on top of phosphor plated film
Apply n-butyl alcohol solution to a thickness of 0.1 μm, dry, and bake at 200°C for 30 minutes to make polysilicic acid.
It was used as a protective film.

Next, one focus of the condenser consisting of a spheroidal mirror is aligned with the surface of the metal magnetic medium as shown in Figure 1, and a continuous wave carbon dioxide laser with an output of 250 W and a beam diameter of 1 cm is focused to a spot diameter of 0.1 mm. The polysilicic acid was fired by irradiation and a magnetic disk was made.

Example 2 Same as Example 1, but output as a light source
500W, carbon dioxide laser with a beam diameter of 1cm,
A magnetic disk was fabricated using a spheroidal mirror shown in FIG. 2 with two focal points aligned with the surface of a metal magnetic medium as a condenser.

Comparative Example A magnetic disk was produced in the same manner as in Example 1, except that a polysilicate film was irradiated and fired without using a condenser.

When a scratch test with a 0.03R sapphire needle was performed using each of the magnetic disks shown in Examples 1 and 2 and the comparative example, scratches occurred on the polysilicate surface in the comparative example under a load of 140 g. Examples 1 and 2
No scratches occurred up to a load of 160 g.

It should be noted that in both Examples and Comparative Examples, there was no polishing property and no magnetization of the nickel-phosphorous film, and after 30,000 times with a magnetic head.
There were no abnormalities at all in the CSS test.

Further, the irradiation time per surface was several minutes or less in the case of a disk with a diameter of 14 inches, but in the case of the comparative example, it required more than 10 minutes. Furthermore, when a light concentrator was used, a light source with an output of 50 W was sufficient to obtain the same scratch strength as the comparative example.

From the above, it was found that the magnetic disk manufactured by the method for manufacturing a magnetic storage body of the present invention has superior reliability and mass productivity.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing embodiments of the present invention, respectively, and show cross-sectional views of a magnetic storage body, a condenser, and a lens. In the figure, 1 is a base, 2 is a base, 3 is a magnetic medium, 4 is a protective film, 5 is a condenser, 6 is a laser beam, 7 is a lens, and F and F' are the focal points of the condenser.

Claims (1)

[Claims] 1. A magnetic storage body in which a mirror-polished base body is coated with a magnetic medium, the magnetic medium is coated with polysilicic acid, and the polysilicic acid is fired by irradiating laser light. A method for manufacturing a magnetic memory body, comprising irradiating a laser beam using a condenser. 2. The method for manufacturing a magnetic storage body according to claim 1, wherein the condenser is a spheroidal mirror. 3. The method of manufacturing a magnetic storage body according to claim 2, wherein one of the two focal points of the spheroidal mirror is provided on the surface of the magnetic medium. 4. The method of manufacturing a magnetic storage body according to claim 2, wherein two focal points of the spheroidal mirror are provided on the surface of the magnetic medium. 5. The method of manufacturing a magnetic storage body according to claim 3, wherein the rotation axis of the spheroidal mirror is not included in the plane of incidence.