JPS5938649B2 - Magnetic memory and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage body used in magnetic storage devices (magnetic disk devices, magnetic drum devices, etc.).

In general, there are two types of recording/reproducing methods for a magnetic storage device that includes a recording/reproducing magnetic head (hereinafter referred to as a head) and a magnetic storage body, as follows.

The first method is to set the head and the magnetic storage surface in contact at the start of operation, and then apply a required rotation to the magnetic storage to create an air layer between the head and the magnetic storage surface. This method creates a space and records and plays in this state.

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 start of the operation. The second method is to apply a required rotation to the magnetic storage body in advance, and then suddenly press the head onto the magnetic storage body surface, thereby creating a space equivalent to an air layer between the head and the magnetic storage body surface. , this is a method of recording and reproducing in this state.

Thus, in the first method, the head and the magnetic storage surface are in a frictional contact state at the start and end of the operation, and in the second method, the head and the magnetic storage surface are in a frictional contact state when the head is pressed against the magnetic storage surface. The frictional force generated between the head and the magnetic storage body in these contact friction states causes wear on the head and the magnetic storage body, 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 causes the load applied to the head to become uneven, which may cause scratches on the surface of the head and the magnetic storage body. Furthermore, during recording and reproduction, 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 breakdown between the head and the magnetic memory, it is necessary to coat the surface of the magnetic memory with a protective film. Traditionally, metal plating films (e.g. Cr, Rh, Ni-P, etc.) have been used as protective films.
There are methods such as coating the gold-layered magnetic thin film medium with oxides, or oxidizing the surface of the gold-layered magnetic thin film medium to form an oxide to form a protective film, but neither of these methods is effective against the above-mentioned contact friction phenomenon. The present inventor has already proposed a protective film made of polysilicic acid that eliminates these drawbacks (Japanese Patent Application No. 50-81).
201). This protective film made of polysilicate sufficiently withstands the contact friction between the head and the magnetic memory, and also withstands sudden contact of the head with the magnetic memory, and also protects the metal magnetic thin film even under high temperature and high humidity conditions. It has sufficient properties as a protective film, such as protecting and not impairing the magnetic properties of the underlying metal body containing the magnetic storage body.

However, some heads tend to draw dust between the head and the magnetic memory, and the dust acts as an abrasive and wears down the head and the magnetic memory, and the abrasion particles generated by the abrasion further abrade the head. and some that wear out the magnetic memory.

This phenomenon is more pronounced in heads with a tapered front. SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic memory having a protective coating that sufficiently protects a metal magnetic thin film medium even from the above-mentioned heads that tend to attract dust, and a method for manufacturing the same.

The magnetic storage body of the present invention is constructed by coating a metal magnetic thin film medium on a mirror-polished non-magnetic disk-shaped substrate, and coating the metal magnetic thin film medium with double or more polysilicate films. .

Also included is a structure in which at least one layer of this polysilicate film contains a silane coupling agent. In the method for manufacturing a magnetic storage body of the present invention, a metal magnetic thin film medium is coated on a mirror-polished nonmagnetic disc-shaped substrate, and further,
After applying a solution of tetrahydroxysilane, which is a hydrolyzate of tetraalkoxysilane, with or without a silane coupling agent, the entire body is heated to a temperature above room temperature and changes in the magnetic properties of the metal magnetic thin film medium are observed for recording and reproduction. The solution can be reapplied onto a polysilicic acid coating with or without a silane coupling agent formed by treatment at a temperature that does not affect the coating, and double or double A magnetic storage body is manufactured by forming a polysilicate film containing or not containing the above-mentioned silane coupling agent on the metal magnetic thin film medium.

Next, the present invention will be explained in detail with reference to the drawings. The figure is a cross-sectional view showing one embodiment of the magnetic storage body of the present invention. In the figure, the magnetic storage body 7 of the present invention has a nonmagnetic disk-shaped base body composed of an alloy disk 1 and a nonmagnetic alloy layer 2 coated thereon, and a mirror-polished surface of the nonmagnetic alloy layer 2. It consists of a coated metal magnetic thin film medium 3 and a protective coating 6 made of polysilicate formed on the metal magnetic thin film medium 3, and this protective coating 6 consists of two layers, a lower layer 4 and an upper layer 5. There is.

The alloy disk 1 must be finished with a surface having sufficiently small waviness (50 μm or less in the circumferential direction and 100 μm or less in the radial direction).

This is because if the waviness is large, the head floating above the magnetic storage body during recording and playback will not be able to follow the vertical movement of the magnetic storage surface, and the distance between the head and the magnetic storage body will change, changing the recording and playback characteristics. It is from. The nonmagnetic alloy layer coated on the alloy disk 1 by plating is mirror-finished to a surface roughness of 0.04 μm or less by mechanical polishing.
In addition, if a metal that can be mirror polished is used for the alloy disk 1,
The nonmagnetic alloy layer 2 becomes unnecessary. A metal magnetic thin film medium 3 for high-density recording is coated on the nonmagnetic alloy layer 2 by plating. The protective coating 6, which sufficiently protects the metal magnetic thin film medium 3 from physical changes such as head contact or chemical changes due to moisture and temperature, is made of polysilicic acid. This protective coating 6 is characterized by being a double layer of polysilicic acid, the lower layer 4 and the upper layer 5. The protective coating 6 is made of a solution of tetrahydroxysilane, which is a hydrolyzate of tetraalkoxysilane. After applying this solution by discharging it while rotating the base bodies 1, 2 and 3, which have now become base bodies 1, 2 and 3, the solution is fired and cooled in an electric furnace to form a lower layer 4, and on top of that, the upper layer 5 is formed by straining in the same manner. formed by.

The above-mentioned polysilicate film contains stress due to the polymerization of tetrahydroxysilane and stress due to the difference in coefficient of thermal expansion with the underlying metal magnetic medium, and cracks or peeling may occur in the film when large external forces are repeatedly applied. be.

Stress due to the difference in thermal expansion coefficient with the underlying metal magnetic medium can be considerably alleviated by layering the polysilicate film. For example, by layering the lower layer 4 and the upper layer 5 as described above, stress can be reduced to the lower layer 4. By holding the protective coating 6 in place and preventing it from being transmitted to the upper layer 5, cracking and peeling of the protective coating 6 can be prevented and the abrasion resistance with the head can be improved.

Furthermore, by incorporating a silane coupling agent into both or one of the lower layer 4 and the upper layer 5, stress can be further alleviated and wear resistance can be improved.

The silane coupling agent referred to here is a type of silane compound represented by the following general formula.

RcSi(Xa)n(Xb)3-N, n is an integer of O to 3.

In the formula, Xb and Xa are springs such as Cl, Br, etc.Although the detailed chemical formula is not clear, in the Rc part, the same unit as above is repeated, and 1st class, 2nd class, 3rd class, etc.
It also includes polyaminosilanes in which organic groups with amino groups of various classes branch in a complex manner to form a matrix as shown in the figure below. (Rogen atom, 0Rd or 0C0Rd(R
d is, for example, a group such as CH3, C2H5, CH2CH2OCH3.

)′＾(represents a part consisting of organic matter.

Examples of such silane coupling agents include the following: The characteristics of the magnetic storage body of the present invention will be explained by examples while comparing with comparative examples.

Comparative example Sufficiently small waviness (50 μm or less in the circumferential direction and 100 μm or less in the radial direction) due to lathe processing and thermal straightening
Approximately 50 μm of nickel-phosphorus (Ni-P) non-magnetic alloy is placed on a disc-shaped aluminum alloy disk with a finished surface.
This nickel-phosphorus plated film was mechanically polished to a surface roughness of 0.04 μm or less and a thickness of approximately 30 μm.
After mirror finishing up to m, a cobalt-nickel-monophosphorus (CO--Ni--P) metal magnetic alloy was plated thereon to a thickness of about 0.05 μm as a magnetic storage medium.

Further, a solution having the composition shown below was thoroughly mixed thereon and then applied by spin coating. That is, the disc-shaped disc, in which the aluminum alloy disc is coated with a nickel-phosphorus film and the cobalt-nickel-phosphorus film is coated thereon, is rotated in a horizontal plane at a speed greater than 200 rpm (revolutions per minute). When a solution having the above-mentioned composition is discharged from the container onto the surface of the disk-shaped disk, the discharged solution wets and spreads on the surface of the disk-shaped disk toward the outside of the ding-shaped disk due to centrifugal force.

As the solvent (ethyl alcohol and butyl alcohol) of the solution discharged onto the surface of the disk-like disk evaporated, a film of polysilicic acid was formed on the surface of the disk-like disk. The disc-shaped disk thus coated with a polysilicate film having a thickness of 0.1 μm was fired in an electric furnace at a temperature of 200° C. for 3 hours to obtain a magnetic disk. Example 1 A magnetic disk was prepared by coating an aluminum alloy disk with a nickel-monophosphorous coating, a cobalt-nickel phosphorus coating on top of the nickel-phosphorus coating, and a 0.1 μm thick polysilicate coating on top of the nickel-phosphorus coating in the same manner as in the conventional example, and firing the same. Then, a polysilicic acid film was applied again to a thickness of 0.1 .mu.m in the same manner as in the conventional example and fired into a disk shape to obtain a magnetic disk.

Example 2 A magnetic disk was prepared in the same manner as in Example 1, except that the coating solution was changed to one having the composition shown below, and the film thicknesses of the lower and upper layers of polysilicic acid were each 0.05 μm.

Example 3 A nickel monophosphorous coating was applied to an aluminum alloy plate in the same manner as in the conventional example, a cobalt nickel monophosphorous coating was applied on top of the nickel monophosphorous coating, and a solution having the same composition as in the conventional example was applied on top of the nickel/r-1-J. YO 齣揩P11 + 書漚行な板士1 Intestines q vo 8 I to L were dried, then a solution of the above composition was again applied thereon by the above method, and baked in an electric furnace at a temperature of 200°C for 3 hours. This was used as a magnetic disk.

Example 4 In the same manner as in the conventional example, a nickel monophosphorus coating was applied to an aluminum alloy plate, a cobalt nickel phosphorus coating was applied on top of the nickel phosphorus coating, and a solution having the composition shown below was coated on top of the nickel monophosphorus coating, and polyester was applied as a silane coupling agent. A polysilicic acid film containing aminosilane is formed, dried at room temperature for 10 minutes or more, and then a solution having the following composition is applied again by the above method, 2
A magnetic disk was obtained by firing in an electric furnace at a temperature of 00° C. for 3 hours.

Example 5 In the same manner as in the conventional example, a nickel monophosphorus coating was applied to an aluminum alloy plate, a cobalt nickel monophosphorus coating was applied on top of the nickel monophosphorus coating, and a solution having the composition shown below was coated on top of the nickel monophosphorous coating, and N was applied as a silane coupling agent. - A polysilicate film containing beta(aminoethyl)-gamma-aminopropyltrimethoxysilane is formed, dried at room temperature for 10 minutes or more, and then a solution having the following composition is applied thereon again by the above method. A magnetic disk was produced by firing the product in an electric furnace at a temperature of 30°C for 3 hours.

In a recording and reproducing method using each of the magnetic disks shown in Comparative Example and Examples 1 to 5, the head and the magnetic disk surface are always in contact at the start and end of operation.
This operation start and end operation test was repeated for 10,0 minutes using a tapered head that easily pulled in dirt at the front.
After repeating this process 00 times, about 10% of the friction marks on the head of the magnetic disk of the comparative example were peeled off, but in Examples 1-
There was no peeling in each of the magnetic disks No. 5.

Claims (1)

[Claims] 1. A metal magnetic thin film medium is coated on a mirror-polished non-magnetic disc-shaped substrate, and the metal magnetic thin film medium is coated with two or more polysilicate films. A magnetic memory body characterized by: 2. The magnetic memory body according to claim 1, wherein at least one layer of the polysilicate coating coated in two or more layers contains a silane coupling agent. 3. A gold-layered magnetic thin film medium is coated on a mirror-polished non-magnetic disc-shaped substrate, and a tetrahydroxysilane solution or a tetrahydroxysilane solution containing a silane coupling agent is applied on top of this, and then A polysilicate film or a polysilicate film containing a silane coupling agent is formed by treating the entire body at a temperature above room temperature at which changes in the magnetic properties of the metal magnetic thin film medium do not affect recording and reproduction. A magnetic memory and a method for manufacturing the same, characterized in that the film is formed in two or more layers by repeating the formation of the film using the same method.