JPS6014408B2 - Method for manufacturing magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a long magnetic recording medium suitable for high-density recording, and relates to improvements in vacuum deposition technology.

Vacuum evaporation method, ion plating method, sputtering method, wet plating method,
The usefulness of vapor phase deposition methods and the like is already known.

However, there is a method to attach a ferromagnetic film with a high coercive force, which is essential for high-density magnetic recording, to a polymer molded substrate with strong adhesive force, and to stably obtain the maximum length that can cope with the rapid increase in the amount of magnetic tape used. Vacuum evaporation methods such as electron beam evaporation are expected to be the most promising.

However, the techniques disclosed so far in this field are insufficient in terms of mass production. That is, the method for most stably obtaining a high coercive force is the so-called oblique evaporation method disclosed in Japanese Patent Publication No. 1984-19 Sokei.

This requires that the angle of incidence, expressed by the angle between the normal to the base and the vapor flow, be 45 degrees or more, and the vapor deposition efficiency is as low as 2 to 3%, and improvements are expected.

In view of this point, the present invention further improves the technique previously proposed by the present inventor in Tokkoshi No. 74702/1982, and proposes a method that particularly leads to improved performance when a multilayer structure of magnetic layers is used. It is something.

An apparatus for carrying out the present invention is shown in FIG. 1, and the details of the present invention will be explained below in accordance therewith.

The inside of the vacuum chamber 1 is continuously evacuated by a vacuum exhaust system 2 to maintain a vacuum atmosphere. Here, what is meant by vacuum atmosphere is that, in the same way as in the above state, inert gas, reactive gas, etc. are introduced from the outside by adjusting the variable IJ valve 3, and the partial pressure of a specific gas is adjusted. It also includes an enlarged state.

A base material 5 made of a polymer molded product is placed in a vacuum atmosphere and moves along the circumferential side of the cylindrical rotary can 4.

When the base material 5 moves in the A direction, it is mounted on a winding shaft 6 and is rolled up on a winding shaft 7 after vapor deposition. Of course, when a multilayer structure of magnetic layers is obtained continuously, the relationship between unwinding and unwinding when a plurality of cans and evaporation sources are arranged will naturally change accordingly, and is common knowledge to those skilled in the art. However, it is clear that this does not limit the present invention.

An evaporation source suitable for the present invention is an electron beam evaporation source, which is schematically shown in FIG. 1, but it is not limited to this, and other systems may be used.

The evaporated substance 9 loaded into the water-cooled steel hearth 8 is a fly source 1
Impact heating is caused by accelerated electrons from zero.

Of course, this does not preclude the use of liner technology, and the method of electron gun is also free. The vapor flow 11 obtained by electron impact heating has an evaporation surface within an angle looking into the can (auxiliary indicated by a broken line).

) The vapor flow is limited, and at the same time, the normal line to the evaporation surface is (This is assumed to be considered by projecting it onto a plane.) An important element of the present invention is that g2 and the center axis of the rotation axis of the can are not coincident with each other but are maintained in a shifted state. More specifically, when the direction of rotation is direction A, the displacement of the evaporation source is preferably in the direction indicated by arrow B in FIG. Reference numeral 12 denotes a barrier signboard for restricting the flow of steam, which is often water-cooled.

Incidentally, the angle of incidence is in the range ao to a, and the usefulness of the present invention will be reduced unless a is at least smaller than 450 of the already disclosed diagonal welding. As can be seen from the example, this requirement is fully met.

Another embodiment is the manufacturing apparatus shown in FIG. 2.

This reverses Motomura 5, and when it is in the A direction, Haas 8', A
' direction, the efficiency can be increased by forming a ferromagnetic layer by the steam flow of the hearth 8''. Note that parts in Figure 2 that correspond to Figure 1 have the same numbers with a dash. The first effect of the present invention is that a high coercive force can be obtained at high speed.
To obtain the Fe film with a ratio of 70 disclosed in Publication No. 8y,
It is mentioned that the vapor deposition efficiency can be improved to 15 to 30%.

According to the present invention, the iron group element alone has a limiting angle of 8 and a key F.
-50 to -1oo for e (minus means oo in Figure 1)
=900 to 00, and conversely refers to the tangential component), -200 to -100 for Co, Ni
600-8000e can be achieved in each range of 0-100.

However, in all of these cases, it is important to involve sufficient amounts of oxygen.

Vacuum level: 1 x 10-5 Torr to 1 x 10-4 To
A range of n is preferred. Ion plating in this region does not diminish the effectiveness of the invention and is included in the modified embodiments. In addition, high coercive force can often be obtained by optimizing the conditions using any of the commonly used ferromagnetic materials, such as the addition of other elements such as Si and V, or alloys between iron group elements. . For example, Co99%Sil%
is heated with an electron beam (1 dish V, 1 thigh W), and an average of 2k/
When using mjn as a base material, Si is deposited on a polyethylene terephthalate film (1 film thickness) that has been evaporated at 350 A in 1 x 10-5 Tom of oxygen.
In the magnetic layer thickness range of 0A to 1200A, the coercive force is 0,=
= 00, 4×10-5Ton (all 02 partial pressure) is 7
8 ratio, 7 × 10-5Ton, Hiro00e, 7 × 10-
5~1×10-4 Tom is 940~95 e,
When o,=150, the transport at 4xlo-5Torr is
10300e at 7×10-5 Torr, 8×10-5T
11000e on, 8 x 10-5 Tom ~ 2 x
It shows high values of 1100 to 113 at 10-4 Torr.

The second effect is exhibited in metal thin film magnetic recording media in a multilayer structure used to increase sensitivity.

That is, as shown in FIG. 3, when manufacturing a magnetic recording medium in which nonmagnetic layers 13, 14, 15 and ferromagnetic layers 16, 17, 18 are alternately laminated on a base material 5 (of course, a protective layer is ,
(There is no limit to the number of layers provided on the back layer, etc.), and it is important to configure and manufacture the device so as to have a large S/N ratio at high frequency. Fig. 4 shows that this product is more effective in terms of multi-layer structure than the multi-layer structure using the technology of Tokugan Sho 52-74702 previously proposed by the present inventor (hereinafter referred to as the conventional product). ing.

That is, FIG. 4 is a comparison of the relative sensitivity of the reproduction level when recording at 2 Hz at a tape speed of 4.75 cm/s with a recording head (magnetic gap of 5 degrees). The recording medium used was Co98%Ni2% manufactured with a limiting angle of -5o.
Film 400△, W film (non-magnetic layer) 350A, 1 tsubo thick polyethylene terephthalate film base material (surface roughness, average roughness 0.0 mm) were sequentially multilayered, and a film with no limiting angle (190° ~1900). The number of layers is indicated by the number of magnetic layers. This value is 1.3 times higher for the conventional product manufactured by Machigao No. 52-74702 and 2.0 times higher for the product of the present invention than commercially available commercial quality coated compact cassette tapes. The noise level at that time is 2 to 4 times lower than commercially available products, and the S/N is low.
The improvement in the ratio was obvious. As described above, according to the manufacturing method of the present invention, a magnetic recording medium having a high coercive force can be efficiently obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional front view of a layer for carrying out the manufacturing method of the present invention, FIG. 2 is a cross-sectional front view of another example of the main part of the same device, and FIG. - of magnetic recording media
FIG. 4, a cross-sectional view of the embodiment, is a relative sensitivity characteristic diagram of the magnetic recording medium. 1... Vacuum chamber, 4... Cylindrical can,
5... Base material, 9, 9', 9''... Evaporated substance, 11, 11', 1 1''... Vapor flow, 1
3, 14, 15...Nonmagnetic layer, 16, 17, 1
8...Ferromagnetic layer. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A method for manufacturing a magnetic recording medium in which a ferromagnetic layer is formed on a polymer molded material as a base material while moving the base material along the circumferential side of a cylindrical can in a vacuum atmosphere, The evaporation source is arranged so that the normal line drawn to the center of the evaporation surface of the evaporation surface of the evaporation source, which uses a ferromagnetic material as the evaporation substance, is not aligned with the rotation axis of the cylindrical can, but is shifted. 1. A method for manufacturing a magnetic recording medium, comprising forming a ferromagnetic layer using a limited incident angle component of a vapor flow obtained by heating and vaporizing.