JPS5836413B2 - Magnetic recording medium manufacturing method and its manufacturing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal thin film type magnetic recording medium and an improvement in its manufacturing apparatus, and an object of the present invention is to provide excellent characteristics as a long magnetic tape used for magnetic recording. This is what I did.

Conventionally, in so-called coated tapes in which ferromagnetic powder such as 7-Fe203, Cr02, etc. is mixed with a binder, applied, and cured, the magnetic powder is dispersed in the binder, and the binder cannot be removed in principle. Since then, there has begun to be a limit to the ability to respond to the trend toward higher densities in magnetic recording, and expectations are increasing for metal thin film magnetic recording media that essentially do not require binders.

The method for forming a ferromagnetic metal thin film on a base material is not special, and any known thin film technology such as electrolytic plating, electroless plating, vacuum evaporation, sputtering, ion blating, or vapor phase method may be used. It can also be used.

However, the plating film typified by Co--P, which can be obtained as an excellent magnetic film, has not reached the laboratory scale.

In other words, it is difficult to form a uniform layer on a long base material and has an adhesive strength that can withstand the mechanical pressure generated when the magnetic head and recording medium slide in the current magnetic recording and reproducing equipment. It's hitting the wall.

Other methods are only batch-type, and there are many reports of obtaining thin films with high coercive force, but magnetic recording media can be obtained on long substrates with good reproducibility and at high speed on an industrial scale. I can't find a way.

In view of these circumstances, the present invention has provided a method for producing a thin film with high coercive force at high speed in place of the conventional oblique evaporation method [
Patent Application No. 1982-116932←Special Publication No. 57-29770
[Refer to the publication]] We have discovered a method of improving the magnetic recording medium to reduce noise in the short wavelength range and to obtain a magnetic recording medium with small loss, and at the same time, it is suitable for manufacturing and has practical effects. We also intend to provide manufacturing equipment that can do this.

The thin metal film type magnetic recording medium used in the present invention is typified by the structure shown in FIG.

That is, on the base material 1, a non-magnetic layer 2, a magnetic layer 3, a non-magnetic layer 4,
The magnetic layer 5 is arranged one on top of the other, and other variations include those in which multiple magnetic layers are arranged in the same manner, those in which a protective layer is arranged as necessary, and those in which the magnetic layer is only a single layer. However, for convenience of explanation, the configuration shown in FIG. 1 will be described as an example.

Although the present invention has the effects described below even when applied to the formation of a nonmagnetic layer, it has the effect of significantly improving the magnetic properties important for a magnetic recording medium, so the formation of the magnetic layer will be explained below.

It is assumed that the formation of the magnetic layer is performed in a vacuum atmosphere, but the vacuum atmosphere here refers to a state where the material is evacuated by a vacuum evacuation system, or a state where gas such as oxygen gas is forcibly introduced. Also included, industrially IXIQ"-3Tor4r
? ．．・It means the range of ~1X10-6 Torr.

3, 4, and 6 show a manufacturing apparatus for carrying out the present invention. As can be understood from these figures, the first half of the vapor flow containing a high incident angle (on the base material) It is important that only the vapor stream containing accelerated ions (as opposed to ,
It is necessary to include a high incident angle component that further emphasizes the oblique deposition effect.

If this is applied to the form of a non-magnetic layer, the adhesion strength of the film, which was a problem with the plated film described above, will be improved to the point where there is no problem at all, and the formation of the magnetic layer (combined with the formation of the non-magnetic layer) will be improved. The same applies.

), as shown in Figures 2, 5, and 7, it is possible to obtain high coercive force and good squareness, which are important for high-density recording, as well as fine structural uniformity. This has a remarkable effect on reducing noise in the short wavelength range, which is thought to be based on

FIG. 3 shows an example of the manufacturing apparatus of the present invention.

An electron beam evaporation source facing cylindrical cans 7 and 9 is disposed in a vacuum chamber 6 to face each other.

The electron beam evaporation source includes water-cooled copper hearths 1γ and 18, evaporation materials 8 and 10 charged respectively, and an electron source 19 and 20.
This is schematically shown.

8 is a non-magnetic material and 10 is a ferromagnetic material.

The base material 14 is rolled up into the can 1 by a winding system consisting of a winding shaft 15, a winding shaft 16, a metal roller 24, etc.
.

In order to convert only the first half of the vapor flow 11 obtained by heating and vaporizing the ferromagnetic material 10 into a vapor flow containing accelerated ions, an acceleration electrode 12 is connected between the can 9 and the evaporation source. It is placed at an appropriate position in the middle.

This accelerating electrode 12 is connected to a DC power source 13 via an insulated introduction terminal 25.

Of course, the same effect can be obtained even if the DC power source 13 is connected to an AC power source or even a high frequency power source instead.

It is known that an electron beam evaporation source essentially involves the generation of ions, and with the above configuration, ion plating is performed in the shaded portion of the vapor flow 11.

It is also possible to provide a more active ionization mechanism, and an example of its configuration will be described later.

In most cases, the accelerating electrode 12 is configured in the form of a mesh, but in some cases, it may be configured as a single wire.

This is fundamentally different from covering the entire surface with electrodes and converting the entire vapor flow 11 into ion plating, which is important in relation to noise, which will be described later, and is an important point of the present invention.

The inside of the vacuum chamber 6 is continuously evacuated by an exhaust device 21,
If necessary, a suitable degree of vacuum is maintained by introducing gas such as oxygen from the outside by adjusting the variable leak valve 23.

Reference numeral 22 serves as both an anti-adhesion plate and a partition plate.

In order to obtain the recording medium shown in FIG. 1 using this apparatus, the substrate 14 may be deposited while being moved in the direction A, and after being reversed and rolled back, the deposition may be repeated again in the direction A.

The nonmagnetic material 8 is made of Cr and A7, and the ferromagnetic material 10 is made of Co(S).
i) [Co 9 8%Si 1.8%, 0.2% is other impurities], oxygen 2
Among them, the electron beam power is 101 (V, 16 kW)
The voltage applied to the accelerating electrode 12 is OV~-5.
00V, polyethylene terephthalate film (thickness 10μ) is used as the base material 14, Cr, AA layer is 0.03 to 0.05μ, Co (Si) layer is 0.05 to 0.
．． A magnetic recording medium having the structure shown in FIG. 1 was manufactured by controlling the coercive force within the range of 0.08 μm, and the coercive force was measured.

As a result, although the coercive force differs slightly depending on the underlying material (non-magnetic material), it can be understood from Fig. 2 that the coercive force increases by over 40% compared to the one not based on the present invention (that is, Ov in Fig. 2). be done.

This has been confirmed for several known magnetic materials, such as other iron group elements and their combinations, and the same confirmation has been made for non-magnetic materials and base materials.

The voltage applied to the accelerating electrode 12 is also a commercial frequency AC voltage,
A high frequency voltage of 1'3.56 MHz was also applied, and in each case, a coercive force increasing effect of over 30 to 50% was confirmed.

The magnetic recording medium obtained according to the present invention using a highly smooth base material as the base material 14 has a noise level several dB lower than that of the highest quality commercially available coated type products in the short wavelength range of 5 μ or less. This shows that it can fully meet expectations for high-density orientation.

With regard to increasing coercive force or improving squareness, which will be discussed later, films obtained by the above-mentioned area-wide ion plating tend to have large particle sizes, and because the particle size dispersion is large, it is difficult to use the products of the present invention due to noise. There is a clear difference, especially in the cancellation noise level, indicating the superiority of the present invention.

As an apparatus for carrying out the present invention, the configuration shown in FIG. 4 as a cross section of the main part can also be mentioned as one that can bring about the same effect.

The same parts as in FIG. 3 are given the same numbers.

Two sets of electron beam evaporation sources are arranged facing the can 9, so that when the substrate 14 moves in the direction of the arrow, a vapor flow containing accelerated ions is directed toward the substrate 14 in a region where the initial oblique evaporation effect is high. The arrangement is as shown in Figure 4.

28 and 29 are water-cooled copper hearths, 26 and 2γ are the same ferromagnetic material, and 30 and 31 are electron generating sources, which are the same as in FIG.

25 is an anti-adhesion plate. 32 is a high frequency electrode, which is connected to a high frequency power source (not shown).

Applying this configuration to Fig. 3, Cr/Co(Si)A
A/Co(Si 2 ) was milled.

As can be understood from Fig. 5, which shows the relationship between high frequency power and the squareness of the obtained magnetic recording medium, at 150 W or more, 10
The highest squareness of 0% could be obtained.

Improvements similar to those in the above case were made in other embodiments with respect to coercive force and noise.

Note that a method that can be expected to produce effects similar to those of the present invention is to use separate cans to perform ion plating and electron beam evaporation, but this method involves continuously performing thin film deposition in the same can. It is essentially different from the invention.

That is, even if the base material 14 is moved at high speed, there is a certain time delay, and even if the material is the same, it will be deposited separately, resulting in different physical properties.

Even as a magnetic recording medium, the present invention cannot be surpassed in terms of the above-mentioned noise, and the present invention is still of great value.

Considering the noise aspect in the structure shown in FIG. 4, as can be inferred from the example shown in FIG. .0
1μ is sufficient.

This value does not limit the present invention, and the high frequency electrode shape may be made thinner or a little thicker.
It is a town function due to the relative arrangement of the can, electrode, and evaporation source.

Further, another apparatus for carrying out the present invention will be explained.

This is a contrivance to increase the amount of accelerated ions even more than that shown in FIG. 3 described above in the case where there is only one electron beam evaporation source facing the can.

The configuration shown in FIG. 6 is the same, and 9, 14, and 24 are as described above.

The electron beam evaporation source is a water-cooled copper hearth 35 and an evaporation material 34.
, an electron source 36 is shown as in the previous example.

FIG. 6 schematically shows a method of ionizing only the first half of the vapor flow 33 using hot cathode plasma.

That is, since a wide base material 14 is used industrially, parallel plate electrodes 38 and 39 extending in a direction perpendicular to the plane of the paper are provided.

Efforts to make the width uniform in the width direction are naturally made and will be omitted here, but the simplest method is to set the width of the base material 14 to W.

If 1.4Wo or more, these parallel plate electrodes 38, 39
You can reach your goal if you take the time to do so.

One side 38 of this pair of parallel plate electrodes has a horizontally elongated (obviously extending in the width direction) hole through which thermionic electrons pass.
It has the effect of creating a plasma state even at 10-5 Torr level depending on the conditions.

Reference numeral 40 denotes an accelerating electrode, which is not always necessary, and depending on the potential of the plasma, the effect of the present invention can be obtained even without this, but it is preferable to provide it in terms of controllability and stability. .

However, the voltage applied here (often negative) is not necessarily as high as it should be, and the acceleration voltage of 400V in Fig.
As can be understood from the example of characteristic a) IOOOV (characteristic b), it is necessary to find appropriate conditions based on relative arrangement relationships, etc.

In Fig. 6, the part surrounded by a broken line is the power supply arrangement placed outside, and the hot cathode heating power supply (either AC or DC may be used) 42
A perforated parallel plate electrode 38 is arranged at the same potential as this one end,
It is composed of a DC power source 41 for placing the other parallel plate electrode 39 at a positive potential with respect to the parallel plate electrode 38.

Figure 1 shows Cr/Co(Si), AA'/Co(Si)
This is a diagram depicting the change in coercive force using the discharge current as a parameter, and the effect that can be doubled by the present invention can be seen here.

The data shows that the voltage between the parallel plate electrodes was constant at 150 V, and the discharge current was changed by changing the hot cathode power supply voltage.

As is clear from the above embodiments, the present invention makes only the first half (relative to the base material) containing the high incidence angle component of the vapor flow of the magnetic material directed toward the base material into a state containing accelerated ions. By doing this, it is possible to manufacture magnetic recording media with high coercive force, good squareness, low noise in the short wavelength range, and low loss on a production scale. It is of great industrial value and can be said to have made an extremely high contribution to the field of magnetic recording, which is oriented toward high-density recording.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the magnetic recording medium obtained by the present invention 6, FIG. 2 is a coercive force characteristic diagram of the magnetic recording medium, and FIG. 3 is an embodiment of the manufacturing apparatus. 4 is a schematic configuration diagram of the main parts of a manufacturing apparatus in another embodiment, FIG. 5 is a characteristic diagram showing the squareness ratio of a magnetic recording medium obtained by the same apparatus, and FIG. 6 is a diagram showing another example. Fig. T is a characteristic diagram showing the coercive force of a magnetic recording medium obtained by the apparatus. 1...Base material, 2, 4...Nonmagnetic layer, 3
, 5...Magnetic layer, 6...Vacuum chamber, γ,
9... Cylindrical can, 8, 10, 26, 2γ,
34... Evaporation material, 11,33... Vapor flow, 12,40... Accelerating electrode, 14...
... Base material, 32 ... High frequency electrode, 31 ...
・・Hot cathode, 3B, 39・・・Parallel plate electrode・

Claims (1)

[Claims] 1. A magnetic layer is formed on the surface of the base material by directing a vapor flow obtained by heating and vaporizing a magnetic material to the base material moving along the circumferential side of a cylindrical can in a vacuum atmosphere. A method for manufacturing a magnetic recording medium, characterized in that, during formation, only the first half of the vapor flow containing high incident angle components contains accelerated ions. 2. A cylindrical can is provided to guide the substrate moving in the vacuum chamber, and an electron beam evaporation source for heating and vaporizing the magnetic material is provided opposite to the cylindrical can, and the electron beam evaporation source and the cylindrical can An apparatus for manufacturing a magnetic recording medium, characterized in that an ionization means is disposed between the electron beam evaporation source and the ionization means for making only the first half of the vapor flow from the electron beam evaporation source containing accelerated ions into a state containing accelerated ions. 3. A patent claim characterized in that two sets of electron beam evaporation sources are arranged facing each other in one cylindrical can, one of which is capable of performing ion plating and the other capable of performing electron beam evaporation. An apparatus for manufacturing a magnetic recording medium according to item 2. 4 Electron beam evaporation sources are arranged facing each other in two cylindrical cans, and the first half of the vapor flow emitted from each electron beam evaporation source can be ion plated, and the second half can be electron beam evaporated. An apparatus for manufacturing a magnetic recording medium according to claim 2, characterized in that it is configured as follows.