JPH01156473A - Manufacturing equipment for thin film magnetic recording medium and method of application thereof - Google Patents

Abstract

PURPOSE:To prevent flaw occurrence at the substrate surface and the surface coated with film by rotatably disposing all guide rollers except a can roller and applying proper tension to a film substrate during its travel. CONSTITUTION:In a coiling-type sputtering device, coiling-cum recoiling rollers 4a, 4b, guide rollers 5a, 5b, 6a, 6b, 7a, 7b, and dancer rollers 8a, 8b, except a can roller 9, are rotatably disposed. Then, a flexible plastic substrate 12 is stretched on respective rollers mentioned above in succession and is allowed to travel, and sputtering is applied from cathodes 3a, 3b to form a thin magnetic film. At this time, as the plastic substrate 12, a film finished into a smooth surface of <=20Angstrom surface roughness Ra is used. Dry plating is carried out while allowing this film substrate 12 to travel under the conditions of >=550g/mm<2> tension to be applied. By this method flaw occurrence at the time of forming a thin magnetic film can be prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an apparatus for manufacturing thin-film magnetic recording media for high-density magnetic recording, using a winding type dry plating apparatus, and a method of using the same, particularly for complex applications. The present invention aims to effectively prevent flaw defects caused by slippage between a film substrate and a roller, which are likely to occur in a dry plating apparatus having a roller system.

(Prior art) When a plastic film is used as a substrate and a magnetic film for magnetic recording is continuously formed on the surface thereof, dry plating techniques such as sputtering and vacuum evaporation are widely used. A complicated roller-type winding sputtering device is used, which includes a roller that can be used for both unwinding and winding, a can roller, and a large number of guide rollers.

By the way, when forming a magnetic thin film using such a winding type sputtering device, it is particularly important to run the plastic film substrate continuously and stably since it is a long object. .

Conventionally, film running has been stabilized by driving not only the can roller but also part of the guide roller in synchronization with the can roller.

(Problems to be Solved by the Invention) However, in the above-mentioned winding type sputtering apparatus,
It is extremely difficult to match the circumferential speed of the can roller and the guide roller in micron units, and slipping occurs between the film substrate and the can roller or guide roller, resulting in scratches on the film substrate and even damage. Problems remained in that the durability and magnetic recording ability of thin-film magnetic recording media deteriorated.

The present invention advantageously solves the above-mentioned problems, and effectively prevents the occurrence of flaws during the formation of a magnetic thin film, thereby preventing the formation of thin film magnetic recording media without deteriorating durability or magnetic recording performance. The purpose of the present invention is to propose a device that can advantageously produce the same, as well as an effective method for using the same.

(Means for Solving the Problems) Hereinafter, the apparatus of the present invention will be specifically explained in comparison with a conventional apparatus.

FIG. 1 schematically shows an example of a roll-up sputtering device that is a typical dry plating device.

In the figure, number 1 is the vacuum chamber, 2 is the connection to the vacuum exhaust system, and 3a
, 3b are cathodes, each with a target attached to its surface. 4a and 4b are rollers 5a that serve both for winding and unwinding the plastic film, respectively.

5b, 6a, 6b, 7a and 7b are all guide rollers, 8a and 8b are dancer rollers, and 9 is a can roller. Note that 10 is a mask, 11 is an inert gas inlet, and 12 is a film substrate such as a plastic film.

Now, conventionally, guide rollers 5a, 5b, 6a, 6
b and dancer rollers 8a, 8b were all able to rotate freely, but the guide rollers 7a, 7b were designed to stabilize the film feed, and the plastic film 1
In order to prevent slipping between the can roller 9 and the can roller 9, the can roller 9 was rotated in synchronization with the feed speed of the can roller 9. By doing this, we were able to run it fairly stably even on slippery film substrates.

Then, a thin film magnetic recording medium was manufactured by depositing a magnetic thin film on a film substrate using the above sputtering apparatus.

Incidentally, when manufacturing a magnetic recording medium consisting of a single-layer magnetic thin film, sputtering is performed with a necessary target placed on at least one of the cathodes 3a and 3b, so that the magnetic thin film is continuously formed on the running film. can be created. In addition, 2 consisting of a soft magnetic film and a perpendicular magnetization film
When manufacturing a layered perpendicular magnetic recording medium, the cathode 3
Targets for a soft magnetic film and a perpendicularly magnetized film are arranged at a and 3b, respectively, and when two magnetic thin films can be formed at the same substrate temperature, the can roller 9 is heated to a predetermined temperature to form a film substrate 12. Take up roller 4
By simultaneously operating the two cathodes 3a and 3b while winding the magnetic material at the time of winding, a two-layer magnetic layer can be formed. If it is necessary to change the substrate temperature when forming the soft magnetic film and the perpendicularly magnetized film, first set the can roller 9 to a temperature suitable for forming the soft magnetic film and sputter from the cathode 3a to soften the film. After forming a magnetic film, the temperature of the can roller is changed to a temperature suitable for forming a perpendicularly magnetized film, and the film substrate 12 is sputtered from the cathode 3b while being fed in the feeding direction.

In any case, it is important to apply a certain tension to the film substrate 12 in order to make the film substrate 12 run stably.

Therefore, conventionally, as mentioned above, the guide roller 7a
, 7b are rotated in synchronization with the can roller 9, thereby stabilizing the running of the film substrate.

Further, it was considered that a small additional tension of about 30,037 mm" was sufficient.

In the conventional winding type sputtering device, the means for synchronizing the circumferential speed of the can roller 9 with the circumferential speed of the guide rollers 7a and 7b, which have significantly different diameters, is mainly a gear having an appropriate tooth ratio. was used. In some cases, the can roller 9 and the guide roller 7a,
7b by separate rotation control systems to synchronize the two.

However, with the synchronization means as described above, it is extremely difficult to completely match the circumferential speed of the can roller and the circumferential speed of the guide roller in micron units, which has caused various problems as described below.

In other words, if the film substrate slips on the can roller or guide roller and fine metal powder, etc. adheres to the roller surface, scratches may develop on the film substrate or magnetic thin film in the winding direction (MD method). (length of tens to hundreds of microns) occurs.

Furthermore, if the film substrate is run while the can roller is heated, the film substrate slips in a complicated trajectory, resulting in a trajectory bottom. This is because the film substrate alternately stretches and contracts not only in the MD direction but also in the width direction (TD force direction) on the can roller.

When a flaw like the one described above occurs on a magnetic thin film, a part protruding from the normal plane is formed at least around the flaw, so the magnetic film is severely damaged when it is slid by a magnetic head. As a result, not only the durability deteriorates, but also there is a possibility that a signal bias error may occur.

Therefore, as a result of intensive research to solve the above problem, the present inventors decided to deactivate the guide roller, which was conventionally driven in synchronization with the can roller in order to stabilize the running of the film substrate, so that it could rotate freely. We have found that this is extremely effective in achieving the intended purpose.

The present invention is based on the above findings.

That is, the present invention is provided with a large number of guide rollers including a winding roller, an unwinding roller, and a can roller, as well as a dry plating device, and while the flexible plastic substrate is sequentially passed around the above roller group and run, the surface of the substrate is coated. This is an apparatus for manufacturing a thin-film magnetic recording medium in which a magnetic thin film is formed, in which all guide rollers except a can roller are installed to freely rotate.

In the present invention, the dry plating apparatus refers to a sputtering apparatus, a vacuum evaporation apparatus, an ion blating apparatus, and the like.

However, in actual use of the device of the present invention, a polyimide film substrate whose surface has an average surface roughness Ra of approximately 20 Å or less has to be run on a polyimide film substrate of 500 g, which was previously thought to be sufficient for running.
When the film was run with a relatively small tension of about /mm2 or less applied, the film substrate slipped on the can roller, resulting in quite long scratches.

However, the inventors of the present invention have conducted extensive research on this issue and have found that the above problem can be solved advantageously by increasing the tension applied to the film substrate during travel to 550 g/mm or more, which is higher than before. We have determined that this is the case.

That is, the second aspect of the present invention is drive type winding.

Equipped with an unwinding roller, a can roller, a large number of freely rotatable guide rollers, and a dry plating device, a magnetic thin film is coated on the surface of a flexible plastic substrate while the substrate is run around the rollers in sequence. In an apparatus for manufacturing a thin film magnetic recording medium, a film whose surface is finished with a smooth surface with a centerline average roughness Ra of 20 Å or less is used as a plastic substrate,
And the film substrate is applied tension: 55037mm"
This is a method of using a thin film magnetic recording medium manufacturing apparatus, which comprises performing dry plating while running under the above conditions.

Here, a polyimide film is particularly advantageously suitable as the above-mentioned film substrate.

(Function) In the winding type manufacturing apparatus having the roller system of the present invention, the can roller is the only roller involved in driving the film substrate other than the winding roller and the unwinding roller. The film substrate is transported by the frictional force between the film substrate and the substrate. Therefore, if the tension applied to the film substrate is increased so that the above frictional force exceeds the value, the film substrate will run without slipping between it and the can roller, and as a result,
The occurrence of defects is advantageously avoided.

Furthermore, in the present invention, as described above, since the film substrate is transported by the frictional force between the substrate and the can roller, it is natural that the surface condition of the can roller and the surface condition of the film substrate are necessary for good conveyance. becomes a problem. The surface of the can roller is usually precisely polished to about 0.1S, so this does not pose a particular problem, but if the surface is rougher, a stronger tension will be required. Regarding this point, the same can be said about the surface of the film substrate.

Therefore, in the present invention, the surface roughness of the film substrate is limited to 20 Å or less in terms of center line average roughness Ra, and this allows the film substrate to be relatively rough even within the range of applied tension of 550 g/mm2 or more. It can be transported well under low tension.

Although FIG. 1 shown above shows the case where there is only one can roller, the present invention can also be applied to an apparatus having two can rollers in order to coat both sides of a film substrate with a magnetic thin film. Needless to say.

It is also possible to coat both sides of a film substrate with magnetic thin films using the apparatus shown in FIG.
After coating one side of the film substrate with a magnetic thin film, remove the take-up roller and unwind roller, re-set them so that they are facing downwards (the top facing state is shown in the same figure), and repeat the same process. The magnetic thin film may be formed by any appropriate means.

(Example) Comparative Example 1 In the apparatus shown in FIG. 1 above, the guide roller 7a
, 7b is rotated in synchronization with the can roller 9 using a conventional roller system, Ra: approximately 2.
0 people, 50 on a polyimide film substrate with a thickness of 50 μm
The film substrate was run while applying a tension of 0 g/m+n2, omitting the formation of the magnetic film.

When the front and back surfaces of the film substrate after running were observed with an optical microscope, the surface (guide roller 7a) was observed.

A unidirectional bottom having a length of approximately 100 μm and extending in the direction of the MD force was generated on both the surface in contact with the can roller 9) and the back surface (the surface in contact with the can roller 9).

Incidentally, the occurrence of such flaws was the same when the tension applied to the film substrate was 800 g/mm''.

Comparative Example 2 Using the same roller-based device and polyimide film as in Comparative Example 1, a permalloy soft magnetic film (thickness 1 μm) and a Co-C
A two-layer magnetic recording medium consisting of a perpendicularly magnetized r-alloy film (thickness - μm) was manufactured. At this time, the can roller 9
The permalloy film was formed by water cooling, and the Co-Cr alloy film was formed by heating to 150°C.

When the front and back surfaces of the thus obtained two-layer magnetic recording medium were observed using an optical microscope, unidirectional flaws were observed on the surface (the surface on which the magnetic thin film was deposited), as in Comparative Example 1, and the number of flaws was On the back surface (film substrate surface), where J had increased, not only a similar unidirectional bottom was observed, but also trajectory-like defects as schematically shown in FIG. 2 were observed. The locus-like flaws occurred symmetrically with respect to the center line of the film substrate. This indicates that the polyimide film running on the can roller was slipping in the MD force direction and TD force direction.

Note that these flaw occurrence phenomena hardly changed even when the tension applied to the polyimide film was increased to 800 g/mm2.

Example 1 In the apparatus shown in FIG. 1 above, the guide roller 7a
, 7b was also made to rotate freely using a roller system and the same polyimide film substrate as in Comparative Example 1. A permalloy film (thickness: 20.0 mm) was applied to both sides of the film substrate under the condition of an added tension of 550 g/mm2. 5 μm) was coated.

When the thus obtained thin film magnetic recording medium was observed under an optical microscope, almost no scratches were observed on either the front or back surfaces.

In addition, the tension applied to the film substrate is 500g/mn+
``When lowered to below, no slipping occurred when the can roller and the film substrate came into contact, that is, when the permalloy film was coated on the surface, but when the permalloy coated surface came into contact with the can roller, that is, when the film substrate was coated, no slipping occurred. When a permalloy film was formed on the back surface of the substrate, slipping occurred on the can roller, resulting in long unidirectional scratches.

Example 2 Using the same equipment and polyimide film as in Example 1, a permalloy film (thickness at knee μm) and a Co-
A two-layer magnetic layer consisting of a Cr alloy film (thickness: μm) was formed thereon. At this time, the can roller was water-cooled when the permalloy film was coated, and on the other hand, when the CO-Cr alloy film was coated, the can roller was water-cooled.
Heated to 0°C.

Almost no unidirectional flaws or locus-like flaws were observed on the front and back surfaces of the thus obtained two-layer magnetic recording medium, and compared to Comparative Example 1, the number of such flaws was less than 1/20, and the length of the flaws and The size could be reduced to 1710 or less.

(Effects of the Invention) Thus, according to the present invention, when dry plating a magnetic thin film on a polyimide film base, the occurrence of scratches on the film substrate surface or the surface on which the magnetic thin film is coated can be significantly reduced compared to the conventional method. This is highly effective in not only improving the durability of the resulting thin film magnetic recording medium but also reducing pit errors.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a sputtering apparatus according to the present invention, and FIG. 2 is a diagram schematically showing a locus-like flaw. 1... Vacuum chamber, 2... Connection to vacuum exhaust system, 3a
, 3b... cathode, 4a, 4b... roller for winding and unwinding, 5a,
5b, 6a, 6b, 7a, 1b...Guide roller, 8a, sb...Dancer roller, 9...
... Can roller, 10... Mask, 11... Inert gas inlet, 12... Plastic film.

Claims (1)

[Claims] 1. A large number of guide rollers including winding and unwinding rollers and canning rollers and a dry plating device are provided, and the flexible plastic substrate is sequentially passed around the above roller group while traveling. 1. An apparatus for manufacturing a thin-film magnetic recording medium in which a magnetic thin film is coated on the surface of a substrate, characterized in that all guide rollers except a can roller are installed to rotate freely. 2. Equipped with driven winding, unwinding and canning rollers, a large number of freely rotatable guide rollers, and a dry plating device, while the flexible plastic substrate is sequentially passed around the above roller group. In an apparatus for manufacturing a thin film magnetic recording medium in which a magnetic thin film is coated on the surface of the substrate, a film whose surface is finished with a smooth surface with a center line average roughness Ra of 20 Å or less is used as the plastic substrate, and the film substrate is . A method of using a thin-film magnetic recording medium manufacturing apparatus, characterized in that dry plating is performed while running under conditions of an added tension of 550 g/mm^2 or more.