JPS61120345A - Production of vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain stably a wrinkle-free medium by using a cylindrical can of which the peripheral surface is coated with a fluororesin film is used and making the potentioal of a conductive film different from the potentioal of the cylindrical can. CONSTITUTION:The cylindrical can of which the peripheral surface is coated with the fluororesin film is used as the cylindrical can and the potential of the conductive film is made different from the potential of the cylindrical can in the stage of forming a vertically anisotropic film consisting essentially of Co and Cr by a vacuum deposition method on a substrate which travels along the peripheral surface of the cylindrical can heated to >=80 deg.C and consists of a high polymer material formed with the conductive film on the surface. Even if, for example, the substrate 8 is deformed, the deformation of the substrate 8 is pressed on the can 2 with slipping on the film 14 and is flatly stretched, by the electrostatic attraction force generated by the potential difference between the conductive film on the substrate 8 and the can 2 and by the small coefft. of friction owing to the film 14. The substrate 8 sticks tightly to the can 2 without wrinkles via the film 14 interposed therebetween, thus arriving to a part 13 for forming the Co-Cr film to be deposited by evaporation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a perpendicular magnetic recording medium having excellent high-density recording characteristics.

Conventional Structure and Problems The perpendicular recording method is known as a method with excellent short wavelength recording characteristics. This utilizes residual magnetization in the direction perpendicular to the film surface of the medium. Therefore, this method requires a perpendicularly anisotropic film in which residual magnetization remains in the direction perpendicular to the film surface.

As a vertically anisotropic film, a so-called Co--Cr vertically anisotropic film containing Co and Cr as main components has excellent properties. Co-Cr vertically anisotropic films are produced by sputtering methods and vacuum evaporation methods (including methods in which a film is deposited by ionizing some of the evaporated atoms, such as the ion blating method), but especially the latter method is used. The method allows very high film deposition rates to be achieved and has reached mass production.

However, as will be explained below, when a Co--Cr vertically anisotropic film was actually fabricated by vacuum evaporation, a problem occurred in that various wrinkles were generated. If wrinkles occur, it is impossible to use the material as a magnetic recording medium, and some kind of solution is required.

As a method for producing a vertically anisotropic Co--Cr film by vacuum evaporation, the best method is to perform evaporation while moving the substrate along the periphery of a cylindrical can.

FIG. 1 is a front view of the interior of a conventional vacuum evaporation apparatus for producing a Co--Cr vertically anisotropic film.

A substrate 1 made of a polymeric material runs along the circumferential surface of a cylindrical can 2. Reference numerals 3 and 4 are a substrate entry roller and a substrate exit roller, respectively, which guide and run the tape-shaped substrate 1. 6 is an evaporation source, and 6 is a shielding plate. The operation of the conventional vacuum evaporation apparatus configured as described above will be explained below.

The substrate 1 made of a polymeric material guided by the substrate entry row 23 travels along the circumferential surface of the cylindrical can 2 as it rotates, and is guided to the winding side by the substrate exit row 24. Note that the temperature of the circumferential surface of the cylindrical can 2 can be arbitrarily set to around 350°C. Evaporation source 6 is Co-C
The r-alloy ingot is heated and evaporated. Due to the shielding plate 6,
Only evaporated atoms having a component close to normal incidence adhere to the substrate 1 made of a polymeric material to form a Co--Cr vertically anisotropic film.

However, when a Co--Cr vertically anisotropic film is manufactured with the above configuration, the following problems occur. That is, Co-C
When a signal is recorded and reproduced in a perpendicularly anisotropic film, a film with a large coercive force Hc in the direction perpendicular to the film surface can obtain a high reproduction output. The temperature of HC soil increases as the substrate temperature Tsub during vapor deposition increases. In order to put a Co-Cr vertically anisotropic film into practical use, a Hc soil of at least 300"6o is required, but experiments have shown that the substrate temperature Tgub during evaporation must be 80°C or higher. The result was clear.

More preferably, a film having a value of soo'6o or more is required as the HC soil, but in this case, the substrate temperature Tsub during vapor deposition must be 150° C. or more. Note that the substrate temperature Tsub during vapor deposition mentioned here refers to the temperature of the peripheral surface of the cylindrical can.

Further, as the polymer material, polyethylene terephthalate, polyimide, or polyamide films are suitable in terms of surface properties, stability, and mass productivity. However, when these films are used for vapor deposition at a temperature of 80° C. or higher on the circumferential surface of the cylindrical can 2 by the method shown in FIG. 1, wavy wrinkles occur in the vapor deposition area.

FIG. 2 is a three-dimensional diagram showing how wavy wrinkles are generated on the substrate 1 at this time, and 7 indicates the wavy wrinkles. It has been found that such a undulation number 7 occurs in the vapor deposition part when the contact between the cylindrical can 2 and the substrate 1 is insufficient. Therefore, one possible way to prevent this is to form a conductive film on the substrate 1 made of a polymeric material, create a potential difference between this conductive film and the cylindrical can 2, and bring them into close contact by electrostatic attraction. . Note that when permalloy or Ti is used as this conductive film, the recording/reproducing characteristics and orientation of the perpendicular magnetic recording medium are improved.

FIG. 3 is a three-dimensional diagram showing a state in which a Co--Cr film is deposited by providing a potential difference between the conductor film and the cylindrical can 2 as described above. Reference numeral 8 denotes a substrate made of a polymer material on which a conductive film is formed on the surface (the surface not in contact with the cylindrical can 2). The voltage applied between the conductor film and the cylindrical can 2 may be either a direct current voltage or an alternating current voltage. According to the above method, the wavy number 7 as shown in FIG. 2 disappears, but random wrinkles 9 occur when the substrate 8 comes into contact with the cylindrical can 2. The cause of the occurrence of these random wrinkles 9 can be considered as follows. When the substrate 8 comes into contact with the cylindrical can 2, the cylindrical can 2 is heated to a high temperature, and the substrate 8 is rapidly heated and deformed. The substrate 8 is tightly attached to the cylindrical can 2 due to electrostatic attraction without being deformed.
Random wrinkles 9 occur.

FIG. 4 is a three-dimensional view of a device that attempts to improve the random wrinkles 9 in FIG. 3. The configuration of this device is almost the same as that in FIG. 3, or the difference in FIG. 4 is that the substrate entry row 23 is replaced with a nip roller 3'. The surface of the nip roller 3' is generally made of rubber. A substrate 8 made of a polymeric material and having a conductive film formed on its surface is pressed against the cylindrical can 2 by a nip roller 3' when it starts coming into contact with the cylindrical can 2. However, even with this configuration, when the temperature of the cylindrical can 2 is raised and a voltage is applied between the substrate 8 and the cylindrical can 2 to produce a Co-Cr vertically anisotropic film, the substrate 8 is moved to the cylindrical can. 2, deformation occurs due to rapid heating, and before this deformation is corrected, it is pressed down by the nip roller 3', resulting in creases 10.

As described above, in the conventional structure, when a Co-Cr perpendicular anisotropic film is deposited on a substrate made of a polymer material, it cannot be done stably without wrinkles, and it cannot be used as a magnetic recording medium. It had

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems, and aims to provide a method for stably manufacturing wrinkle-free and good perpendicular magnetic recording media.

Structure of the Invention The present invention is based on a substrate made of a polymeric material with a conductive film formed on the surface, which is running along the circumferential surface of a cylindrical can heated to 80°C or higher. When forming the vertically anisotropic film as a component by vacuum evaporation, the cylindrical can whose circumferential surface is covered with a fluorine-containing resin film is used, and the conductor film and the cylindrical can are This is a method of manufacturing a perpendicular magnetic recording medium in which the cans are set to different potentials, and by using the method of the present invention, a perpendicular magnetic recording medium without wrinkles can be stably obtained.

DESCRIPTION OF EMBODIMENTS FIG. 5 is a front view of the inside of a vacuum evaporation apparatus for explaining an embodiment of the manufacturing method of the present invention.

In the figure, the cylindrical can 2 is grounded.

Further, the substrate entry side roller 3 and the substrate exit side roller 4 are powered by a power supply in order to create a potential difference between the conductor portion on the surface of the substrate 8 made of a polymer material with a conductive film formed on the surface and the cylindrical can 2. 11.

Note that the potential may be positive or negative, or may be alternating current.

Further, the substrate 8 begins to come into contact with the cylindrical can 2 at the location indicated by the arrow 12, and this location is referred to as a contact start portion. Reference numeral 13 denotes a deposited film forming section, in which a Co--Cr vertically anisotropic film is formed. Reference numeral 14 denotes a heptad-containing resin film provided on the circumferential surface of the cylindrical can 2 so that the substrate 8 can easily slide. Next, consider changes in the substrate 8 from the time it enters the cylindrical can 2 to the time it leaves the cylindrical can. The substrate 8 first comes into contact with the heated cylindrical can 2 at the contact initiation portion 12 (indirectly through the fluorine-containing resin film 14) and is rapidly heated, which may cause deformation. If there is no fluorine-containing resin film 14, the substrate 8
Due to the potential difference between the conductor film thereon and the cylindrical can 2, the cylindrical can 2 adhered tightly to the cylindrical can 2 before its deformation was corrected, causing random wrinkles or creases. On the other hand, when there is a fluorine-containing resin film 14, the coefficient of friction between it and the substrate 8 is small, so even if the substrate 8 is deformed, the fluorine-containing resin film 14 has a small friction coefficient between the conductor film on the substrate 8 and the cylindrical can 2. Due to the electrostatic attraction caused by the potential difference, the deformation is suppressed by the cylindrical can 2, and it slides on the fluorine-containing resin film 14 and is stretched flat. In this way, the substrate 8 is coated with the fluorine-containing resin film 14.
The film adheres tightly to the cylindrical can 2 without wrinkles through the space between them, and reaches the Co--Cr vapor deposited film forming portion 13. Next, in order to prevent the formation of wavy wrinkles as shown in FIG. It is sufficient that a sufficiently large electrostatic attraction force acts between the cylindrical cans 2. Fluorine-containing resin film 1
4 is inserted between the substrate 8 and the cylindrical can 2, although the electrostatic attraction is weakened, it is sufficient to increase the potential difference between the conductive film on the substrate 8 and the cylindrical can 2. As you can see, the method of the present invention does not cause wrinkles at all.

Note that the specific voltage value of the power source 11, the thickness of the fluorine-containing resin film 14, the temperature of the cylindrical can 2, the width and thickness of the substrate 8, the thickness of the conductive film on the substrate 8, etc. are dependent on each other. However, it varies depending on the case.

In addition, when the Young's modulus of the substrate 8 is high, wrinkles may not be completely removed in some cases, but the wrinkles can be removed by heating the substrate 8 between the contact initiation part 12 and the deposited film forming part 136 using a halogen light 15 to soften it. no longer occurs at all.

Next, specific examples of the present invention will be described.

A ζ-malloy film with a thickness of 3oQO is deposited on a polyimide film with a width of 15cm and a film thickness of 5oμm using the vacuum evaporation apparatus shown in Fig. 5 (the diameter of the cylindrical can 2 is 6QcrIL), and then Co − with a film thickness of 1500 people
A Cr vertically anisotropic film was deposited according to the method of the present invention. However, both ends I Cm in the width direction of a film with a width of 115 cm are:
No vapor deposited film was formed as a margin part. That is, the width of the deposited film is 13 cm. During the permalloy film deposition, the temperature of the circumferential surface of the cylindrical can 2 was set at room temperature, so no wrinkles were formed. The conditions for further vapor-depositing the Co-Cr vertically anisotropic film on the permalloy film are as follows: the temperature of the cylindrical can 2 is 100°C, the fluorine-containing resin film 1 is
4 has a thickness of 30 μm, and the metal roller 3°4 is powered by the power supply 11.
A voltage of -5ooV was applied to. There were no wrinkles in the perpendicular magnetic recording medium after the vapor deposition was completed.

In addition, the Hc soil of the Co-Cr vertically anisotropic film is 7QO'6
°, demonstrating excellent short wavelength recording and reproducing characteristics.

DETAILED DESCRIPTION OF THE INVENTION According to the method of the present invention, it is possible to completely remove the wrinkles that conventionally occur when depositing a vertically anisotropic Co-Cr film on a substrate made of a polymeric material. It is possible to provide a wrinkle-free perpendicular magnetic recording medium.

[Brief explanation of the drawing]

Figure 1 is a front view of the inside of a conventional vacuum evaporation apparatus for producing a vertically anisotropic Co-Cr film, and Figures 2, 3, and 4 show wrinkles that occur on a substrate in a conventional vacuum evaporation apparatus. FIG. 5 is a front view of the inside of a vacuum evaporation apparatus for explaining one embodiment of the manufacturing method of the present invention. 1.8... Board, 2... Cylindrical can, 3... Board entry roller, 4... Board exit roller, 5... ... Evaporation source, 6 ... Shielding plate, 7 ... Wavy wrinkles, 9 ... Random wrinkles, 1o ... Folded wrinkles, 11 ... ...Power supply, 12...Arrow/contact start part, 13...
・Vapour-deposited film forming part, 14...Fluorine-containing resin film,
15...Halogen light. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2! Figure 3 Figure 4

Claims (2)

[Claims] (1) On a substrate made of a polymeric material with a conductive film formed on its surface, which is running along the circumferential surface of a cylindrical can whose temperature has been raised to 80°C or more, Co and Cr are the main components. When forming the vertically anisotropic film by vacuum evaporation, the cylindrical can whose peripheral surface is covered with a fluorine-containing resin film is used, and the conductive film and the cylindrical can are different. A method for manufacturing a perpendicular magnetic recording medium, characterized in that the medium is made to have a potential. (2) In the method for manufacturing a perpendicular magnetic recording medium according to claim 1, the substrate is heated with a halogen light or the like between the contact initiation portion of the substrate and the cylindrical can to the vapor deposited film forming portion. A method of manufacturing a perpendicular magnetic recording medium, characterized in that: