JPH0154777B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a magnetic recording medium having a ferromagnetic metal thin film layer as a recording layer, and particularly aims to improve a method of controlling coercive force by oblique evaporation. Magnetic recording has responded to demands for higher densities by increasing the coercive force of magnetic recording media, but as wavelengths continue to become shorter, only areas near the surface of the media are magnetized. Therefore, in addition to increasing coercive force, a shift has begun to the use of magnetic materials that have a large saturation magnetic flux density. One is an extension of the conventional coating method, in which fine particles of iron-based ferromagnetic metals 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 oxide. The other type is a medium that does not use a binder and has a ferromagnetic metal thin film as the magnetic recording layer.This type is used in some practical applications under the name evaporation tape because the thin film is formed by vacuum evaporation. It has reached this point. However, since vapor-deposited tape still has a short history, there are still some issues that need to be improved before it can be industrialized. One of these would be the improvement of a stable control method for coercive force. The so-called oblique evaporation method disclosed in Japanese Patent Publication No. 19389/1989 has the possibility of stably controlling the coercive force through evaporation. However, there are two issues that need to be resolved in order to commercialize this technology. One of these is that the deposition efficiency is low, and the other is that the change in coercive force becomes large in response to a slight change in the angle of incidence in the region of large coercive force, which is the problem that the present invention seeks to solve. There are two ways to approach this solution. One is a method that relies on materials, especially an effective combination with atmospheric control, and the other is a method that accurately controls the angle of incidence. Although the present invention mainly relates to the latter, the present invention is equally effective in implementing the former. The present invention will be explained below using the drawings. The figure shows an example of a device for implementing the invention. This is similar to a two-chamber roll-type vapor deposition machine, but it is not necessary to rely on this, and when disposing a non-magnetic layer, it is more effective to dispose two or more cooling supports such as cans. The present invention relates to restrictions in forming the ferromagnetic layer, including the case where a plurality of cooling supports are provided when the ferromagnetic layer is formed by dividing it. In the figure, the rotary can 4 is shown as a cooling support, but instead of using this, for example, a rotary belt connected with thin plates of SUS304 and made into an endless belt driven by a separate drive mechanism can be used. It is also possible to configure the substrate to move along. Along the rotation can 4, the substrate 1 is connected to the feed shaft 11.
Then, it moves to the winding shaft 12. Note that other known elements necessary for winding are omitted. The inside of the vacuum chamber 5 is divided into an upper chamber 6 which mainly houses a winding mechanism for the substrate 1, and a lower chamber 7 which houses an evaporation source, a mask mechanism, etc., and each has an independent exhaust system 1.
0.9 to maintain a predetermined degree of vacuum. Note 1
3 is a partition plate. Although the evaporation source is shown structurally as the container 3 and the evaporation material 2, it is appropriately selected from known evaporation sources such as an electron beam evaporation source, an induction heating type evaporation source, and the like. When forming a film using a partially limited incident angle of the vapor flow emitted from the evaporation source, if the angle of incidence expressed by the angle between the normal to the substrate and the vapor flow is 45° or more, iron, For some alloys of cobalt and nickel, the coercive force starts to increase little by little and increases sharply from around 60 degrees, and at around 75 degrees to 80 degrees, it increases by 50 to 100 with a change of only 2 to 3 degrees in the angle of incidence. A change in coercive force of about O¨e] is observed. In order to prevent this, in the present invention, a mask that limits the angle of incidence is constructed of a metal belt 8, and this belt 8 is used as a moving body (for example, it moves constantly in the direction of arrow B). Scrape off the ferromagnetic material, e.g.
(Move in a plane as necessary to enable effective packing of the ferromagnetic material to be collected). 14 and 15 may be cooled with free rollers or not. Reference numeral 19 is a nip roller, which is used to move the belt.
It goes without saying that the fixed mask 17 must be placed at a position where θ ₁ does not change due to the vapor deposition material attached to the tip T. For convenience, the angle θ ₁ formed by the line connecting S and P is called the incident angle, but the actual evaporation position is not the point S, but there is an evaporation source that is considered to have a volume. Needless to say. The fact that it is important to make the side of the metal belt on which the metal belt is deposited extremely smooth is consistent with the need to effectively scrape off the deposited material with the blade. Next, embodiments of the present invention will be specifically described. [Example 1] Can diameter 100cm, can width 65cm, metal belt
SUS304 65cm width, length 1.5m, = 40cm, =
30cm. Two 9.5μ polyethylene terephthalate films with a width of 50 cm and a length of 3000 m were prepared, one of which was deposited by the present invention at an incident angle of 55°, and the other film was deposited by the conventional method for comparison, that is, by masking the deposition prevention plate 17. The film was deposited at an angle of 55° to the initial value. Among the results, the coercive force was sampled in the longitudinal direction and compared and summarized in the table below.

[Example 2]

Same can as in Example 1, =50cm, =
The incident angle was set at 72° at 35cm, and the polyethylene terephthalate 11.5μm with a matt surface was exposed at 1500m.
A comparison was made in the same manner as in Example 1. The belt movement conditions were 5 cm/sec, and the can temperature was kept constant at 20°C. The coercive force of the magnetic layer with 100% Co controlled to 0.1 μm was investigated at 10 points from the initial stage to 1450 m.
It was extremely stable at 1060-1070〔O¨e〕, whereas with the conventional method, it was controlled to be 0.1μm, but
The moving speed of the substrate is reduced by 30% compared to the initial value (in the case of the present invention, it is a constant speed), and the coercive force is 1050.
It increased from [O¨e] to 1490 [O¨e]. 0.15 μm according to the present invention for Co90% Cr10%
A similar trend was confirmed for the film formed. In the present invention, the coercive force was 1200 to 1220 [O¨e], and in the conventional method, it was 1200 to 1590 [O¨e]. [Example 3] The rotation can diameters were 50 cm, = 34 cm, and = 27 cm, and oxygen was introduced from the outside as a lower chamber atmosphere (0.1/min to 0.16/min), and 2 × 10 ^-5 Torr to 4.5
×10 ^-5 Torr Co100%, Co80% Ni20%, Co95%
W5%, Co98% Rh2%, respectively, were placed on the same polyethylene terephthalate substrate as in Example 2 with a thickness of 0.15 μm.
Deposited. A comparison was made with the conventional method at a deposition length of 2000 m for the cases of an incident angle of 35°, 43°, and 60°. In all cases, the coercive force of the medium according to the present invention was stable;
In the conventional example, the increase in coercive force was noticeable after 1000m. In the case of 80% Co and 20% Ni, there was a 16% increase compared to the initial value at a position of 1950 m, and the maximum rate of change was 37% in the case of 95% Co, 5% W and an incident angle of 60°. [Example 4] The mask mechanism of the present invention was modified and used for purposes other than incident angle control by omitting the adhesion prevention plate 17. That is, in the figure, another belt and blade combination is arranged in a portion K surrounded by a broken line. This made it possible to recover the deposited metal very effectively. This brought extremely high economic effects to the implementation of Co95% Pt5%, etc. As described above, the effectiveness of the present invention is extremely high regardless of the type of substrate or vapor deposition material. Also, with two pairs of these masks, by vertical incidence,
The value of manufacturing the magnetic recording medium of the present invention increases as the length of the magnetic recording medium increases, as it is also effective in obtaining a medium for perpendicular magnetic recording.

[Brief explanation of drawings]

The figure is a diagram showing an example of an apparatus for implementing the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Evaporation material, 3... Container, 4... Rotating can, 5... Vacuum chamber, 8... Metal belt, 11... Winding shaft, 12... Feeding shaft, 16... Doctor blade, 17... Fixed mask.

Claims (1)

[Claims] 1. When depositing a ferromagnetic material onto a polymer molded substrate moving along a cooling support, the angle of incidence of the ferromagnetic material vapor onto the substrate is regulated by a rotationally driven heat-resistant belt. A method for manufacturing a magnetic recording medium.