JPH0668839B2 - Magnetic recording medium manufacturing equipment - Google Patents

Description

The present invention relates to an apparatus for manufacturing a magnetic recording medium, and more particularly to an apparatus for forming a magnetic thin film on a substrate by vacuum deposition.

<Conventional Technology> A continuous thin film type magnetic recording medium in which a metal magnetic layer such as Co—Nu or Co—Cr is formed on a non-magnetic substrate has been attracting attention as a medium for high density magnetic recording, and various research and development have been conducted. Is actively carried out. As one of the methods for manufacturing this magnetic recording medium, there is a method of forming a metal magnetic layer on a non-magnetic substrate (hereinafter referred to as "film") by vacuum vapor deposition. In this method, a metal magnetic layer is deposited as a thin film on a polymer film, which is a substrate that continuously moves in a vacuum chamber, by using an electron gun.

In this device, when the electron gun causes a discharge, the substrate that has passed over the evaporation source during the recovery causes heat damage or appears as wrinkles during winding, and it becomes a film that is wound up later. Since this also has an adverse effect, discharge countermeasures have been an important issue in carrying out continuous vapor deposition for a long time.

<Problems to be Solved by the Invention> The present invention solves the problem that a long power recovery time of an electron gun adversely affects the deposition of magnetic metal on a film.

<Means for Solving Problems> As described above, as a result of various studies on the discharge of the electron gun and the damage to the substrate, the electron gun was discharged and the power of the electron gun was turned off.
Since the electron beam that becomes is also stopped flowing, there are no reflected electrons of the beam or secondary electrons generated by the beam irradiating the molten metal. However, these backscattered electrons and secondary electrons have a great effect on charging the film to enhance the adhesion between the film and the drum for cooling the film.

On the other hand, there is no particular regulation on the restoration time until the power of the electron gun is restored, but it is generally about several seconds from the viewpoint of the degree of vacuum restoration and safety. However, since the film is not charged during this period, the adhesion to the drum is lowered, and the cooling by the drum becomes insufficient. As a result, it was clarified that radiant heat from the evaporation source causes thermal damage to the film and causes wrinkles in the subsequent vapor deposition step. For this reason, a situation such as the formation of the magnetic thin film becomes uneven thereafter, and such a situation should be avoided as much as possible.

In short, the present invention is, for example, a drum which is wound around a non-magnetic substrate such as polyethylene terephthalate film and rotates in a predetermined direction, and a drum such as Co-Ni which is installed apart from the drum for a predetermined period.
A ferromagnetic metal evaporation source, and an electron gun that irradiates the evaporation source with an electron beam. The electron beam emitted from the electron gun melts the evaporation source, and the generated evaporation metal is drummed. It is intended for an apparatus for manufacturing a magnetic recording medium which is deposited on the above non-magnetic substrate to form a thin film of a ferromagnetic metal.

A control circuit for controlling the feeding speed of the non-magnetic substrate is provided so that the following equation is satisfied.

t <rθ / v t: recovery time after discharge of electron gun r: radius of drum θ: maximum incident angle point of vaporized metal with respect to non-magnetic substrate wound on drum, rotation center point of drum, and vaporized metal Central angle v formed by the minimum incident angle point: Feed rate of non-magnetic substrate <Example> An example of the present invention will be described below with reference to the drawings.

The present inventors conducted the following experiment before constructing the present invention.

The vacuum condition is 5 × 10 ⁵ mbr and the thickness is 10 as a non-magnetic substrate.
A film made of polyethylene terephthalate (PET) having a width of 500 μm and a width of 500 mm, an alloy of Co85% and Ni15% is used as a ferromagnetic metal, and the power of the electron gun is 0.1 mm when the power is 50 to 200 kW.
Deposition was performed with a film thickness of. At this time, the relationship between the power recovery time of the electron gun and the damage state of the film at each film traveling speed (film speed) for obtaining the film thickness of 0.1 mm was investigated, and summarized in the following table. The radius r of the rotating drum is 0.5 m, and the central angle θ is 40 ° (2π / 9).

Here, when the power of the electron gun was set to 100 kW or less, the film was not damaged even if the recovery time was increased to 10 S. When the power of the electron gun was set to a normal power of 120 kW or more, when the recovery time shown in the above table was exceeded, the film was temporarily damaged by heat or wrinkles were observed in the running part. FIG. 1 shows an apparatus according to an embodiment of the present invention constructed on the basis of the above experiment. In the figure, 1 is a vacuum chamber, 2
Is a roll-out roll, 3 is a base film, 4 is a guide roll, 5 is a drum, 6 is a guide roll, 7 is a take-up roll, 8 is a shutter, 9 is an evaporation source, 10 is an electron gun, and 11 is a controller.

The PET film 3, which is a non-magnetic substrate, is supplied from a roll 2 and is brought into close contact with the drum 5 and rotated together with the drum. During this period, a ferromagnetic metal is vapor-deposited by using an electron gun 10, and a thin film 12 ( The film on which (see FIG. 2) is formed is wound on a roll 7.

In this structure, when the position of the maximum incident angle α ₁ of the deposited metal on the film 3 is the maximum incident angle point A and the position of the minimum incident angle α ₂ of the deposited metal on the film 3 is the minimum incident angle point B, the maximum incident angle is An acute central angle θ formed by the angle point A, the rotation center point O of the drum 5, and the minimum incident angle point B of the vapor-deposited metal, the recovery time when the electron gun is discharged, t, the film feed speed From the above experimental example, the following relational expression is established among these three in order to prevent problems with the film and the ferromagnetic metal thin film formed on this film. It is necessary.

t <rθ / v (1) Therefore, data is input to the control circuit (controller) 11 so that the feed speed v of the film 3 satisfies the above expression (1).

As mentioned above, increasing the power of the electron gun to 120 kW or more is C
The power for melting and evaporating a ferromagnetic metal such as o-Ni, Co-Cr is a normal value, and the central angle θ is about 40 ° when viewed from the growth of the ferromagnetic metal on the film surface. These are normal angles, and these numerical values are not specific to the method of manufacturing a magnetic recording medium.

In the above equation (1), rθ / v is the time for the film 3 to reach the minimum incident angle point B from the maximum incident angle point A at the feeding speed v (time for the film 3 to pass through the vapor deposition region). The fact that the time is longer (longer) than the recovery time t of the electron gun means that the portion X of the film 3 located at the maximum incident angle point A when the electron gun starts discharging starts vapor deposition again when the electron gun returns. It means that the minimum incident angle point B has not been reached by the time.

The fact that the vapor deposition is restarted before the portion X has reached the minimum incident angle point B means that an undeposited portion where vapor deposition is not performed is not formed on the film 3 while the electron gun returns. Since there is no undeposited portion, the adhesion to the drum is maintained, and the various troubles described above can be resolved.

With the above configuration, the contact between the film and the drum can be maintained well even when the electron gun is stopped, and the film can be prevented from being damaged by heat or wrinkles.

<Effect> Since the present invention has the above-described configuration, the control device appropriately controls the recovery time of the electron gun and the like even when the electron gun is stopped, so that the contact between the film and the drum is well maintained. However, it is possible to prevent heat damage and wrinkles of the film.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a magnetic recording medium manufacturing apparatus showing an embodiment of the present invention, and FIG. 2 is a sectional view of a magnetic recording medium manufactured by the apparatus shown in FIG. 2 ... Unwinding roll, 3 ... Non-magnetic substrate 5 ... Drum, 7 ... Winding roll 10 ... Electron gun, 11 ... Control device 12 ... Ferromagnetic metal thin film

Claims (1)

[Claims] 1. A drum around which a non-magnetic substrate is wound and which rotates in a predetermined direction, an evaporation source of a ferromagnetic metal which is installed at a predetermined distance from the drum, and an electron which irradiates the evaporation source with an electron beam. A magnetic recording medium that includes a gun, melts the evaporation source by an electron beam emitted from the electron gun, and deposits the generated evaporation metal on the non-magnetic substrate on a drum to form a thin film of ferromagnetic metal. The manufacturing apparatus for a magnetic recording medium according to claim 1, further comprising a control circuit for controlling the feed speed of the non-magnetic substrate so that the following expression is satisfied. t <rθ / v t: recovery time after discharge of electron gun r: radius of drum θ: maximum incident angle point of vaporized metal with respect to non-magnetic substrate wound on drum, rotation center point of drum, and vaporized metal Center angle formed by the minimum incident angle point v: Feed rate of non-magnetic substrate