JPS6010369B2 - Method for manufacturing magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the manufacturing method of magnetic recording media such as metal thin film magnetic tapes having high coercive force and high saturation magnetization suitable for high-density recording. The objective is to eliminate practical ridges due to the low efficiency when manufacturing magnetic recording media using in-vacuum film production methods such as the coating method and the Kame field deposition method.

The biggest drawback of the oblique vapor deposition technique disclosed in Japanese Patent Publication No. 41-19-9, which is necessary for achieving a conventional high coercive force, is that the vapor deposition efficiency is low.

In other words, the angle between the normal to the base material surface and the incident vapor flow is 4
? The above shows that in order to obtain a coercive force of 40 e with a 1500 A iron film, the incident angle described above is 700
When a ferromagnetic film is formed using a vapor flow having only such an incident angle, the vapor deposition efficiency is as low as less than several percent, and cannot be put to practical use. The present invention eliminates this drawback, and FIGS. 1 and 2 show an example of an apparatus for implementing the invention.

The main points of the present invention are to perform initial growth of a thin film by oblique incidence, to gradually reduce the incidence angle and pass through direct incidence, and then to gradually increase the incidence angle to grow a ferromagnetic thin film. By averaging the film formation rate and the effect of radiation heat from the evaporation source, it is possible to create a ferromagnetic film with high coercive force, compared to the conventional oblique evaporation method. This is a highly industrially valuable manufacturing method that can increase the deposition efficiency by nearly 1 degree.

This will be explained below with reference to the drawings.

First, in FIG. 1, the inside of a vacuum chamber 1 is maintained in a vacuum atmosphere by an evacuation system 2. Vacuum degree is 1×10-5~5
A pressure of about ×10-5 Torr is often used, but it is of course possible to introduce a reactive gas such as oxygen if necessary. In this vacuum chamber 1, an evaporation source 3 and a base material 4 are placed facing each other. In this case, the base material 4 refers not only to the general-purpose plastic film itself, but also to the base material provided with a non-magnetic layer as necessary, and is a multilayer structure of a non-magnetic layer and a ferromagnetic layer. The case includes the state before the deposition of the desired ferromagnetic layer. The base material 4 is moved from the raw roll 5 along the side surface of a cylindrical rotary can 7 via metal rollers 6 and the like, and is rolled up by a winding roll 8. The present invention does not specify these transport systems, but may be devised as appropriate. The rotating can 7 is heated or cooled as necessary. Although 9 is a signboard, it is not necessary to divide the inside of the vacuum chamber into two.

Although the evaporation source 3 is a resistance heating method, it can be applied to any of the well-known electron beam heating methods. The evaporated metal 3' is made of iron, cobalt, nickel, an alloy thereof, or a non-magnetic element added thereto, and is heated to a predetermined temperature by a heater 3'', becomes a vapor stream, and is directed toward the base material 4. 10 is a heating power source, and 11 is an introduction terminal.

The key point of the present invention is that vapor near the g-line in FIG. 1, which is a line connecting the close distance between the base material 4 and the evaporation source 3, is directed to the base material 4 in an intermittent manner.

This is achieved, for example, by a rotatable shield 12. The shielding material 12 has an axis (not shown) (perpendicular to the page),
If necessary, it is connected to a motor via gears, belts, etc., and its rotation is controlled. Next, specific examples will be described in detail.

A case will be described in which, using the apparatus shown in FIG. 1, a polyethylene terephthalate film (thickness low) on which Ti has been formed in advance at 500 A is used as a base material, and Fe alloy is formed at 1500 A.

The width of the base material is 15 mm, the diameter of the rotating can is 50 mm, the evaporation source is an electron beam heating method with 1 spot W, the close distance between the evaporation surface and the base material is 22 mm, and the rotating shield material is shown in Figure 2 A. A stainless steel plate with a width of 6 skins in the center and 5 skins at the edges and a thickness of 18 cm.
It is formed on the skin and the rotation can be varied within the range of 10 to 150 ratio pm. This shape is not limited to that shown in FIG. 2A, but may be the plate-like shape shown in the opening of FIG. 2, or other shapes.
12' is a rotation axis.

This position was set at 16c from the evaporation surface on the g-line. 3
The saturation magnetization of the Fe alloy film formed in a vacuum atmosphere with an oxygen partial pressure of 5 x 10-5 Ton under the condition of 0 pm was 17,000 Gauss, the coercive force ratio was 39, and the squareness ratio was 0.87, showing excellent characteristics. In addition, the vapor deposition efficiency was as high as 46%.

Regarding Co, even when 40 was obtained and 1500 people were obtained, the vapor deposition efficiency was 43%, which is close to the conventional efficiency of 1, which shows the high industrial value of the present invention. Here, the relationship between the rotatable shielding material 12 and the film formation rate will be explained.

The table below shows the film formation rate (without shielding material) for each incident angle and the shielding time to equalize the film formation rate.

Table * Standard Values As shown in the table above, the film formation rate is highly non-uniform without a shielding material.

During the time when the base material undergoes vapor deposition, the shielding material is applied intermittently, for example, in a mode that changes the angular rotation speed by several tens of revolutions (an example is such that the shielding time is as shown in the table). You can make it more uniform by rotating it. The influence of reflected heat is also equalized using almost the same concept. These allow the ferromagnetic thin film to grow at a constant rate, reducing defects and achieving high coercive force.Although it is shielded, the entire incident angle can be integrated, which increases deposition efficiency. become. Next, another embodiment is shown in FIG.

Note that the same parts as in FIG. 1 are given the same reference numerals. In the figure, the base material 4 has two surfaces that are exposed to the vapor of evaporated metal from the evaporation source 3, consisting of a curved part along the side surface of the rotary can 7 and a surface 13 extending in the tangential direction of the side surface of the rotary can. This shows the case where the

Such a device also has the effects described above,
High vapor deposition efficiency can be obtained.

According to the manufacturing method of the present invention as described above, it is possible to efficiently obtain a metal thin film type magnetic recording medium having high coercive force and high saturation magnetization and suitable for high-density recording.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional front view of one embodiment of the apparatus used to carry out the manufacturing method of the present invention, Fig. 2 A is a sectional view of each example of shielding material used in the same apparatus, and Fig. 3 The figure is a schematic cross-sectional front view of a thousand legs of another embodiment of the apparatus used in the present invention. 1... Vacuum chamber, 3... Evaporation source, 3'...
... Evaporated metal, 4... Base material, 12... Shielding material. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a vacuum atmosphere, ferromagnetic metal vapor is applied near the line of close distance between an evaporation source that uses ferromagnetic metal as the evaporation substance and a base material such as a polymer molded article, and the film formation rate at each incident angle is averaged. A method for manufacturing a magnetic recording material, characterized in that a ferromagnetic layer is formed on the base material by disposing a shielding material that intermittently blocks the light.