JPS60224126A - Magnetic disk - Google Patents

Abstract

PURPOSE:To dispense with Ni-Co-P plating for the formation of a magnetic layer and to obtain the titled disk having excellent strength, etc. by plating Ni-P on a substrate for the magnetic disk comparatively thickly to form a base layer, and forming a magnetic layer by heating only the surface of the base layer. CONSTITUTION:An amorphous base layer 2 of Ni-P is formed on a substrate 1 for a magnetic disk as a layer not having magnetism at ordinary temp. Then a beam from a laser 12 is condensed on an ultrafine spot by using a condenser 13 and irradiated only on the surface part of the layer 2 through a mirror 14, the substrate 1 is rotated at high speed and moved in the radial direction to heat only a part of the surface of the base layer 2, and a magnetic layer 10 is formed. Or the surface is briefly heated by using a flash lamp having high intensity to form the magnetic layer. The surface is magnetized by heating in this way, the hardness of the Ni-P layer is increased, and the removal of generated protrusions which is requied when the magnetic layer is formed by the plating of Ni-Co-P can be dispensed with. Accordingly, the excellent disk is obtained by a small number of processes.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method of manufacturing a magnetic disk (hereinafter referred to as a disk) used in a fixed magnetic disk storage device (hereinafter referred to as a disk device).

<Conventional example> In recent years, disk devices have become more dense, and the coating medium used in the past (alumina powder and magnetic material mixed with a polymeric binder) has been applied to the surface of the side plate. Plating that can reduce the thickness of the magnetic material from 1 μm (approximately 1 μm thick to form a magnetic layer),
A shift is being made to a method of forming a magnetic layer by sputtering or the like.

FIG. 1 shows the structure of a conventional plating medium. In Figure 1, 1 is a substrate made of aluminum material,
The average surface roughness of the surface is approximately 0.005 μm, and the maximum protrusion is approximately 0.02 μm. 2 is a base layer to provide contact resistance, and is made of N with a thickness of about 30 to 40 μm.
1-P is formed by electroless plating. After polishing the surface of this base layer 2 to reduce its surface roughness, N 1-Co-P is formed to a thickness of about 0.08 μm by electroless plating. This layer becomes the magnetic layer 3 for recording information. If left in this state, the magnetic layer 3 will have poor corrosion resistance and wear resistance, and when using a contact start/stop type head, there is a risk that the head will stick to the disk. 0.08 above
A protective layer 4 with a thickness of about μm and a lubricant layer 5 with a thickness of about 0.08 μm are formed.

In such a disk, it is important to make the thickness, composition, crystal structure, etc. of the Ni--Go--P plating of the magnetic layer 3 uniform. If the thickness of the magnetic layer 3 is not uniform, fluctuations in recording and reading signals will increase, causing errors. The magnetic layer 3 is very thin, and the N + - of this magnetic layer 3 is very thin.
The Co-P plating solution is more active than the N1-P plating solution for the base layer 2, and the layer thickness, composition, crystal structure, etc. become non-uniform, causing variations in magnetic properties and making recording and reading difficult. The magnitude of the signal changes. In extreme cases, there may be areas where the plating does not adhere at all. Therefore, not only is it necessary to be extremely careful when handling the board when producing discs, but also
The drawback is that sufficient cleaning and pretreatment (activation) are required.

・〈Object of the Invention〉 The present invention has been made in view of the drawbacks of the above-mentioned conventional examples, and it is easy to make the magnetic layer uniform, and N 1-Go-
The object of the present invention is to provide a disk in which the step of plating a magnetic layer with P is omitted.

<Configuration of the Invention> The configuration of the present invention that achieves this object is that, in a magnetic disk used in a magnetic disk storage device, a relatively thick <Ni-P plating is applied on a substrate to form a base layer; The structure is characterized in that a magnetic layer is formed on the surface of the base layer by heating only the surface.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Note that the same elements as those in the prior art are given the same reference numerals, and redundant explanations will be omitted.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

In FIG. 2, the process is the same as in the conventional example up to step 2, in which a base layer 2 is formed on a substrate 1 by electroless plating, the surface of this base layer 2 is polished, and the surface roughness is reduced.

By the way, the Ni-P of the base layer 2 formed on the substrate 1 is
At room temperature, it has an amorphous structure and has no magnetism. However, when heat treated, it crystallizes and becomes highly magnetic. Figure 3 shows the heating magnetization characteristics of N1-P chemical plating solution.
This figure shows the relationship between heating temperature and saturation magnetic flux density when plating is performed to a thickness of 0 μm and the heating time is 2 hours.

According to Figure 3, non-magnetic Schumer has a saturation magnetic flux density of about 80 Gauss when heated at a temperature of around 280'C, while Blue Schumer has a saturation magnetic flux density of about 1000 Gauss at a temperature of around 250'C.
Gauss or higher, Schumer BO has a saturation magnetic flux density of <1000 Gauss or higher at a temperature of around 30°C. The saturation magnetic flux density of these is 1o.

Blue Schumer or Schumer BO exceeding O Gauss is heated to a temperature around which its saturation magnetic flux density increases. The coercive force of Ni-P subjected to such heat treatment is approximately 2
00 Elsdead (Oe), and can be used satisfactorily as a disc.

The present invention utilizes the magnetization phenomenon of Ni-P as described above,
Heat is applied only to the surface of the base layer 2 of the conventional example, and the surface of the base layer 2 is made into a magnetic material by about 0.1 μm, thereby forming the magnetic layer 10. In addition, if it is necessary to increase the coercive force,
Cobalt (Co 2 ) may be deposited on the magnetic layer 1o. 4 and 5 shown in FIG. 2 are the same protective layer and lubricating layer as in the conventional example.

As a method of applying heat only to the surface of the base layer 2, for example, as shown in FIG.
3, the light is focused into a very fine spot, and the surface of the base layer 2 formed on the substrate is irradiated via the mirror 14. By rotating the substrate 1 at high speed and adjusting the dynamic speed appropriately, a very small portion of the surface of the base layer 2 can be heated to form the magnetic layer 1o.

As a method of making the surface of the base layer 2 magnetic, heating may be performed by irradiating it for a short time using a high-intensity flash lamp.

In this embodiment, an aluminum material is used as the substrate, but the material is not limited to aluminum, and a non-magnetic material such as glass may be used.

<Effects of the Invention> As specifically explained above with the examples, according to the present invention, (1) There is no need to perform Ni-Co-P plating for forming the magnetic layer, so cleaning and pretreatment are also unnecessary. This becomes unnecessary and the process becomes simpler.

(2) Since the magnetic layer is formed by simply heating the surface of the base layer 2, it is easy to uniformly magnetize the entire surface.

(2) When electroless N1-P plating is heated, it becomes magnetic and its hardness increases from about 400HV to about 10001-1V, so the mechanical strength of the disk increases and head crashes become less likely to occur.

(2) When forming the magnetic layer by the conventional method, Ni
When plating -CO-P, protrusions are generated and the surface roughness deteriorates, making it difficult for the head to fly. However, in the process of the present invention, only heat treatment is performed, so no protrusions are generated, and a burnishing process is not necessary.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of a conventional magnetic disk, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing the structure of a conventional magnetic disk.
FIG. 4 is an explanatory diagram showing the heating magnetization characteristics of the i-P chemical plating solution, and FIG. 4 is an explanatory diagram showing one method of magnetizing the surface of the base layer. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Base layer, 10... Magnetic layer. Heating temperature cliff (°C) Figure 4

Claims (1)

[Claims] In a magnetic disk used in a magnetic disk storage device, a relatively thick <Ni-P plating is applied on a substrate to form an M layer, and only the surface of this base layer is heated to form a magnetic layer on the surface of the base layer. A magnetic disk characterized by forming.