JPS58155520A - Manfuacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recroding medium excellent in durability, by making the formation speed of a thin film more speedy than the specific speed and increasing the amount of radiation heat to >=3 times as much as condensed heat, in a method for manufacturing a metallic thin magnetic recording medium by a vapor deposition method. CONSTITUTION:In forming a ferromagnetic substance thin film by applying a vapor of a ferromagnetic substance such as Co alloy directly to a plastic substrate moving along a rotary support (either cylindrical scan or endless belt) having controlled temperatuere, the average formation speed of this thin film is designated as 0.1mum/sec and the amount of radiation heat from the evaporation source to the evaporating substance, e.g., Co alloy is made to >=3 times as much as the condensed heat dissipated when the evaporation substance is deposited on the substrate. Thus, the magnetic recording medium excellent in durability is obtained easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a metal thin film type magnetic recording medium by a vapor deposition method, and aims at improving the method to obtain a medium with excellent durability.

In recent years, high-density magnetic recording with a recording wavelength of 1 μm has been achieved in the consumer field, and in the computer field, from the standpoint of reliability,
Compared to consumer use, the recording wavelength (or pit density in digital recording, usually expressed as the number of information bits per inch BPL) is still long, but
Recording density has been steadily improving.

Recent new developments, including the practical application of some GO alloy-based magnetic thin films, are expected to lead to even greater improvements in recording density, and expectations are particularly high for video applications that require extensive signal processing. .

However, in order to apply it to the currently mainstream helical scanning video tape recorder, it is important to improve the corrosion resistance and durability of the thin film.

In order to promote short wavelength recording, it is not a good idea to provide a protective layer for improving durability, a lubricity imparting layer, etc. on the magnetic layer.

Therefore, it is necessary to improve the thin film itself, and on the other hand, the physical properties of the thin film are highly dependent on the manufacturing method, so it cannot be stabilized.

It is important to find ways to obtain improved media on an industrial scale and in large quantities.

The present invention employs electron beam evaporation, moving along a temperature-controlled rotating support (either a cylindrical can or an endless belt). The basic method is to form a thin film by directing the vapor of ferromagnetic Go gold alloy onto a plastic substrate such as polyethylene terephthalate, polyamide, or polyimide. Evaluate with a value. ] is converted into energy as TePoCW/-], and the radiant heat from the evaporation source is p1(''/J), then it is an important point of the present invention to satisfy P1≧3Po.However, as described below, Thus, the thin film formation rate is 0.1 μ''/sec or more.

This condition is such that the degree of vacuum during evaporation is 8×1σ'Torr ~ 9
X 1 o-”Torr, the atmosphere is oxygen, a mixture of oxygen and an inert gas, etc., and the coercive force is 600 (
Oe) to 2050 (Oe), regardless of the type of magnetic material or substrate. Regarding the relationship between Pl and Po, it is expected that the larger Pl is, the greater the effect will be, but an appropriate value should be selected depending on the heat resistance of the substrate and the cooling conditions during vapor deposition.

It is currently not clear whether it is sufficient to evaluate the relationship between Pl and Po using the average value, but it is probably the case that a film with excellent durability and corrosion resistance is formed when the film is formed at a large angle of incidence. When the film formation rate is low, the incident angle becomes small, and when the film formation rate increases to 0.1 μ''/'sec or more, the formation of defects increases rapidly due to absorption of radiant heat by the deposited film. This is thought to be due to the fact that the defect generation process and defect annihilation (annealing) process compete with each other, resulting in a film with fewer surface defects.

Therefore, for film formation in an oxygen atmosphere at a rate of 0.1 μm/sec or less, good conditions can be obtained even when Pl is 3Po or less, which may reflect the difference in the absorption efficiency of radiant energy. Conceivable.

(This case is indicated by a black circle in FIG. 2, which will be explained later.) However, even if the film is formed in an oxygen atmosphere, it is preferable that Pl be 3Po or more.

FIG. 1 shows the main parts of a vapor deposition apparatus used in an embodiment of the present invention, in which a substrate 1 is placed in a vacuum chamber (not shown) so as to be partially exposed to a vapor flow 3 from an evaporation source 2. configured. In FIG. 1, a cylindrical can 4 is shown as a rotating support. The vapor flow restriction mask 6 serves to control the coercive force.

The film formation speed in the present invention is determined by the substrate movement speed V.
If the thickness of the thin film is tO ((m), the radius of the support for one revolution is ro (cWL), and the angle of exposure to the vapor flow is α [radian] as shown in Figure 1), then tO It is a quantity defined by °v/r·α [cIrL/seC].

The radiant heat is obtained by actually measuring the temperature distribution of the evaporation source and correcting it based on the relative positional relationship.

Comparison (7) 7'c me K, to・v/r, 4 [crn/s
ec] was converted by the heat of condensation specific to the material, the dimension was set to (W/,,!), and both were combined.

In FIG. 1, reference numeral 6 indicates a feeding shaft of the substrate, and reference numeral 7 indicates a winding shaft.

A thin film was formed using the apparatus shown in FIG. 1 under the conditions shown in the table, and a tape of A inch was manufactured at a relative speed of 4.
6m/Seo, using ferrite head.

Durability was evaluated in still mode.

The margin evaluation results below are divided into three stages and displayed on the coordinates of Pa and Pl as shown in FIG.

Note that FIG. 2 also shows many other embodiments that were not shown in the above table.

As is clear from this figure, those in the range of pl>3 po have satisfactory corrosion resistance, and there are no problems when used in combination with a protective layer or a slipperiness imparting layer of an allowable thickness. It was confirmed that there was no.

As is clear from the above description, according to the present invention, a magnetic recording medium with excellent durability can be easily obtained, and the industrial value of the present invention is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main parts of the vapor deposition apparatus used in the examples of the present invention, and Fig. 2 is a diagram for explaining the present invention in detail, and shows the results of evaluating the durability of magnetic thin films under different formation conditions. show. 1...substrate, 2...evaporation source, 4...
...Cylindrical can 0 Name of agent Patent attorney Toshio Nakao and 1 other person 1st
811 Figure 2 PI) (”/cm勺

Claims (1)

[Claims] When forming a ferromagnetic thin film by depositing evaporated material from an evaporation source on a substrate, the average formation rate of the thin film is set to 0.
1 μm/Sec, and so that the amount of radiant heat incident from the evaporation source to the deposition part of the evaporative substance is at least three times the amount of condensation heat released when the evaporative substance is deposited on the substrate. A method of manufacturing a magnetic recording medium, characterized in that: