JPS5832234A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To suppress the change of corcive force caused by a change of incident angle to a practical level, by vapor-depositing ferromagnetic material on a high molecular product substrate which shifts along a cooling supporter while spraying a gas to the substrate from a place near an incident angle control part of an incident angle control mask. CONSTITUTION:A vacuum tank 5 is divided into an upper room 6 and a lower room 7 with a partition plate 13. A high molecular product substrate 1 wound round a send-out shaft 11 of the room 6 is shifted to the room 7 along a cooling supporter 4. Then a gas is sprayed to the substrate 1 from the tip P0 of an incident angle control mask 8. The air current of a ferromagnetic material 2 is vapor-deposited on the substrate 1 so that the line connecting the tip P0 and the center S of an evaporation source container 3 form a certain angle theta1 with the normal line set up at a point D crossing the substrate 1. Then the substrate 1 is taken up to a take-up shaft 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film as a recording layer, and is aimed at solving problems that occur when industrializing oblique evaporation.

Magnetic recording has responded to demands for higher densities by increasing the coercive force of magnetic recording media, but as wavelengths become shorter, only those near the surface of the media become magnetized. The output cannot be increased only by increasing the coercive force;
The transition to materials with high saturation magnetic flux density has begun.

One is an extension of the conventional coating method, in which fine particles of ferromagnetic metals such as iron or alloys, which are diluted with a non-magnetic material such as a binder but have essentially a high saturation magnetic flux density, are used instead of iron. The other type is a medium that does not use a binder and has a ferromagnetic metal thin film as its magnetic recording layer.Since vacuum deposition is used to form the thin film, it is sometimes called a vapor deposition tape. It has come to be offered to

This vapor-deposited tape has a short history, and there are many issues that await investigation and improvement on an industrial scale.

One of these is the control of coercive force, and the development of technology to stably control a particularly large coercive force is an important theme.

The so-called oblique vapor deposition disclosed in Japanese Patent Publication No. 19389/1989 has the possibility of stably controlling the coercive force by vapor deposition.

However, the disadvantages of this method are that the deposition efficiency is low;
The phenomenon in which the coercive force changes as the angle of incidence changes becomes more pronounced as the coercive force increases.

The present invention aims to suppress changes in coercive force caused by changes in incident angle to a practical level, and the present invention will be explained below using the drawings.

FIG. 1 shows a vapor deposition apparatus used in an embodiment of the present invention. Although this figure shows an example in which the vapor deposition apparatus has a two-unit configuration, the invention is not limited to this, and various modifications that satisfy the requirements described below are naturally included in the present invention.

As shown in the figure, the substrate 1 is configured to be moved from a feed shaft 11 to a rotary can 4 and to be rolled up by a winding shaft 12. In this figure, other elements of the winding system, such as a free roller and an expander roller, are omitted, but it goes without saying that they may be included as necessary.

The rotary can also functions as a cooling support.For example, an endless belt made by electron beam welding of thin plates of 5US304 can be used instead, or it can be used for repeated vapor deposition. It is also within the scope of the present invention to use multiple cans.

The evaporation source disposed opposite the rotary can 4 may be any known evaporation source, but electron beam heating is preferable. In FIG. 1, the evaporation source container 3 and the evaporation material 2 are schematically shown, and the electron source is not shown.

The vacuum layer 6 is divided into an upper chamber 6 and a lower chamber 7.

13 is a partition plate. Upper chamber 6. The lower chamber 7 is normally exhausted by independent exhaust systems 10 and 9, respectively.

8 is a mask that limits the angle of incidence, and when the center of the evaporation source is S and the tip of the mask is Po, the extension of SP8 is
The angle θ1 between the normal line and the point intersecting the substrate (along the circumferential side of the can) represents the incident angle of the vapor.

The mask 8 is configured so that the gas is injected from the vicinity of Po. This prevents the magnetic vapor from accumulating in the vicinity of Po, so that θ determined by SPo can always be kept constant when dealing with long lengths.

As long as this is satisfied, the shape of the mask or mask may be a part of a circular arc or a combination of straight lines, and is not subject to any limitations. In addition, it is preferable that gas introduction be carried out using known stable introduction, long-term flow rate and pressure control techniques.
The type of gas may be active, inert, or a mixed gas depending on the purpose.

Next, embodiments of the present invention will be specifically described.

[Example 1] The substrate was made of polyethylene terephthalate 10.5 μm (
600 width), incident angle θ1 = 70°, 0080%
A Ni2O% alloy layer was formed to a thickness of 0.1 μm. The degree of vacuum in the lower chamber was 2×10 Toyy.

The coercive force of the obtained magnetic layer was 1060 [6e] and the squareness was 0.96.

As a comparative example, Ar gas was used at 0 and 117 min (I
FIG. 2 shows the present invention carried out while introducing gas (Kp/crl) and the conventional example carried out without introducing gas. Sampling is performed in the longitudinal direction and the distribution in the width direction is
Indicated in the form of -.

As is clear from this, it is understood that in the case not according to the present invention, the coercive force increases and the uniformity in the width direction also deteriorates.

Similar comparisons were made for the following examples, but 2.000
Comparison only at the time of vapor deposition and immediately after the start [Example 2] A magnetic layer made of 100 Co was formed to a thickness of 0.2 μm at an incident angle θ1 = 73° on polyethylene terephthalate 16 μm (width 500). Ar0. IQ 7m i
The total length deposited under the introduction of n (1'Fy/Cdl) is 2
050m, the vacuum level is 1,7X10 Tor in the lower chamber.
It was r. In the present invention, the obtained coercive force is initially 1
At 000 m and 2000 m, the squareness ratio was 1200 [OeJ, 0-97, and the v trace p uniformity did not change.

When formed without introduced Ar, the coercive force varied from 1220 to 1410 boe at 1000 m.

At this time, the thickness of Co accumulated at the tip of the mask was 19111 mm, and the incident angle was substantially changed.

[Example 3] Bo IJ xy 7f L/7 j'1'
, , 5pm (500-width pressure and incident angle θ1 work 60°
A magnetic layer consisting of 15% Coas% Cr was formed. Degree of vacuum: 1×V1゜TorrSAro, 2R/m1n (1
%m/cn), Aro, and osQ 7min. Iooom time point 7 ・The initial value is coercive force 980 [Os], squareness ratio o, 98
It was also uniform in the width direction.

After examining this example in detail, it is 2000m.

As the length increases to 3000 m, Ar 0.2 Q
Compared to 7 m in, there are signs of a slight change in coercive force at Ar O, 05 fi/min, and a slight dependence on flow rate can be seen, but the required flow rate should be optimized depending on the injection hole diameter, spacing, etc. is preferable.

[Example 4] On a polyamide substrate of 8.6 μm, Co80
A magnetic layer consisting of 20 layers was formed to a thickness of 0.15 μm. Oxygen is introduced into the lower chamber through a mask, and the vacuum level is 4.5X1.
Vapor deposition was performed using 0-6 Toyy. At θ1=460, the amount of introduced 02 was 0.22 L/min (If&/crl).

Coercive force is 920 [Oe], squareness ratio 0.88, 4000m
It was uniform throughout the length in both the width and length directions.

When θy1 = 20', the coercive force is approximately 1 at 1000m
5% increase, same 34% increase at -2000m, 3
In ooOm, to control the deposited film thickness, the film movement speed must be reduced by 40%, or the power of the electron beam input must be reduced by 30%.
It can be said that the present invention can maintain the set conditions and overcome the drawbacks in terms of film thickness control.

In addition, for RF ion brating, a high frequency electrode is placed between the film and the evaporation source, and 13.56MHz
In addition to confirming the effect of the present invention by performing ion brate ink at high frequency,
o -Mn, Co-Ti, Co-5t, Co-
Ni-Cr.

Co--Pt and the like were also confirmed.

Regarding the introduced gas, N2. Co2. We also investigated Co, etc. and confirmed the effectiveness of the present invention.

Even if these results are combined, the mechanism of coercive force generation (
For example, it has been confirmed that the present invention is effective regardless of magnetocrystalline anisotropy, shape anisotropy, strain, etc.), and its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a vapor deposition apparatus used in an embodiment of the present invention, and FIG. 2 is a diagram for explaining the present invention in detail. 1...Substrate, 3...Evaporation source container, 4.
... Rotatable can, 6... Vacuum chamber, 8...
...Mask, 11...Feeding axis, 12...
River m cut shaft, 9.1o...exhaust system. Name of agent: Patent attorney Toshio Nakao
1 figure

Claims (1)

[Claims] When evaporating a ferromagnetic material onto a polymer molded substrate moving along a cooling support using a mask for regulating the angle of incidence of the vapor deposition air flow onto the substrate, a portion near the angle of incidence regulating portion of the mask is deposited. A method for manufacturing a magnetic recording medium, characterized in that vapor deposition is carried out while injecting gas from a magnetic recording medium.