JPH0426920A - Production of magnetic disk - Google Patents

Abstract

PURPOSE:To improve the electromagnetic conversion characteristics and recording density by forming a magnetic layer on a rigid substrate, then subjecting the magnetic layer to an annealing treatment at a specific temp. or above and at the temp. at which the substrate is not affected. CONSTITUTION:After the magnetic layer is formed on the rigid substrate, the magnetic layer is subjected to the annealing treatment at >=200 deg.C and at which the substrate is not affected. An Ni-P plated substrate formed by subjecting the surface of an aluminum substrate to Ni-P plating, an alumite substrate formed by anodizing the surface thereof to form an oxide film, etc., are adequate if the aluminum substrate is used as the rigid substrate. The temp. of the annealing treatment is 200 to 300 deg.C with the Ni-P plated substrate, 200 to 400 deg.C with the glass substrate and 200 to 400 deg.C with the alumite substrate. The electromagnetic conversion characteristics and recording density are improved in this way as compared with the untreated substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a magnetic disk such as a so-called hard disk.

(Prior art) So-called hard disks, in which a magnetic layer is formed on a rigid substrate such as an aluminum substrate or a glass substrate, have characteristics such as excellent responsiveness, large storage capacity, good storage stability, and high reliability. However, with the trend towards higher density recording, there is a need to further improve the electromagnetic conversion characteristics.

Therefore, various studies have been made in the past in order to improve the electromagnetic conversion characteristics of hard disks.

For example, optimization of sputtering conditions when forming a ferromagnetic metal thin film, selection of magnetic materials, improvement of substrate surface shape, miniaturization of flying hides, etc.

[Problem to be solved by the invention]

However, for example, it seems that magnetic materials have been fully developed, and further miniaturization of flying hides causes the problem of head crushing, so the limits of each method are becoming apparent. Also, in the above method,
Although it is technically difficult, the reality is that no significant effects can be expected, and the development of some new technology is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional situation, and an object of the present invention is to provide a method of manufacturing a magnetic disk that can improve electromagnetic conversion characteristics using a simple technique.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the method for manufacturing a magnetic disk of the present invention includes forming a magnetic layer on a rigid substrate, and then
The method is characterized in that the annealing treatment is carried out at a temperature of 1.5 C or higher and that does not affect the substrate.

Materials for the μs-resistant substrate include aluminum, glass,
Any material used as a substrate material for ordinary hard disks, such as ceramics, can be used. In particular, in the case of an aluminum substrate, a Ni--P plated substrate whose surface is plated with Ni--P, an alumite substrate whose surface is anodized to form an oxide film, etc. are suitable.

On the other hand, the magnetic layer may be a magnetic coating film formed by applying a magnetic paint made by kneading magnetic powder with a binder, or may be a magnetic coating film formed by applying a magnetic coating material such as Co-Cr, Co-Ni, Co-Ni-C
A ferromagnetic metal thin film formed by directly forming a ferromagnetic metal material such as r, Co-Cr-Ta, etc. by a method such as vapor deposition, sputtering, or plating may be used.

In the latter case, a base film of Cr or the like may be formed.

Further, the thickness of the magnetic layer may be within a normal range and is not particularly limited.

In the present invention, to perform annealing treatment, after forming a magnetic layer on a rigid substrate, heat treatment is performed for 0.5 to 3 hours in the air or in an inert gas atmosphere such as nitrogen gas.

The temperature of the annealing process is preferably a temperature that provides the maximum effect without affecting the substrate of the disk, and the temperature varies depending on the type of substrate. The optimum temperature for annealing treatment depending on the substrate is shown below: Ni-P plated substrate 200~300℃ Glass substrate 200~400''C alumite substrate
The temperature is 200-400°C. 200℃ in both cases
If it is less than that, no effect will be obtained. Also, here N i −
The reason why the upper limit of the processing temperature for the P-plated substrate is lower than for other substrates is that the N1-P-plated substrate has a property of becoming magnetic due to heat, which may affect the characteristics of the magnetic layer.

[Function] After a magnetic layer is formed on a rigid substrate, annealing treatment at a temperature of 200° C. or higher that does not affect the substrate improves electromagnetic conversion characteristics and recording density compared to an untreated layer.

〔Example] The present invention will be explained below based on specific experimental results.

The sample disk used in the experiment was a magnetic disk in which a Co-Cr based magnetic film was spun-coated on an A.1 substrate with an N1-P plating film as the base, and a Co-Cr based magnetic film was further deposited via a Cr base film, and the coercive force Hc was 1300. (Oe).

This sample disk was heated in a clean oven for 30 minutes.
After heat treatment (annealing) for 11 hours at 0'C, electromagnetic conversion characteristics and recording density were measured. For comparison, we also measured the unannealed material.

The measurement was carried out using a metal-in-gap (MIG) type composite magnet at a magnetic disk rotation speed of 3600 r.
pm, and the write current was set to 48 Amp-p.

Table 1 shows the output characteristics and resolution of each sample disk, and Table 2 shows the results of the override characteristics (0/W) and CN ratio.

In addition, in Table 1, LF and HF are each 1.25 MHz.
, the output for a 3.33MHz signal, and in Table 2, I
D and OD are trunk radius 1B, 00mm position, 30. The overlay I characteristic at the tOmm position is shown.

(Margins below) Table 1 Table 2 It can be seen that output characteristics, resolution, override characteristics, and CN ratio are improved by annealing the disk.

On the other hand, FIG. 1 shows the relationship between recording density and output. It is generally considered that it is possible to use up to 50% of the total output, and when comparing the recording frequency at D50, which indicates 50% output, the annealed magnetic disk has
This value is higher than that of the untreated one, indicating that annealing improves the recording density of magnetic disks.
E was given.

〔Effect of the invention〕

As is clear from the above description, in the present invention, the electromagnetic conversion characteristics and recording density of a magnetic disk can be improved by a simple means of annealing the magnetic disk.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between recording density and output.

Claims (1)

[Claims] A method for manufacturing a magnetic disk, which comprises forming a magnetic layer on a rigid substrate and then performing an annealing treatment at a temperature of 200° C. or higher that does not affect the substrate.