JPS6089828A - Manufacture of vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent generation of folds of a magnetic film by forming a conductive film on a high polymer base, running the base side in contact with a heating cylinder circumferential face, making the conductive film and the cylinder equipotential at the start of contact, bringing the potential to a different potential and vapor-depositing and forming a Co-Cr vertical orientation magnetic film. CONSTITUTION:The Co-Cr alloy magnetic thin film is formed by vapor-depositing a raw material to the conductive film through an open hole of a shiled plate 6 from a vapor-deposition source 5 while a base 8 provided with conductive film such as ''Permalloy'' or Ti on the surface of polyimide film or the like is run along the circumference of a cylinder can 2 heated to >=120 deg.C. The conductive film and the can 2 are made equipotential among the base 8, the first contact position 12 of the can 2 and a metallic roller 15 up to the vapor deposition part 14 so as not to produce an electrostatic attracting force and the potential of the can 2 and that of the conductive film are made different at a position 13 at which the roller 15 and the base 8 are parted from the can 2 so as to improve the adhesion between the base 8 and the can 2 with the electrostatic attracting force. Thus, after folds or the like of the base 8 produced by rapid thermal expansion at the initial contact are lost, the base is adhered so as to obtain a smooth high quality magnetic recording medium.

Description

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

(Structure of conventional example and its problems) A 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 magnetized film in which residual magnetization remains in a direction substantially perpendicular to the film surface. As a perpendicular magnetization film, a so-called Co--Cr perpendicular magnetization film containing CO and Cr as main components has excellent characteristics. Co-Cr perpendicular magnetization films are produced by sputtering methods and vacuum evaporation methods (including methods such as ion silating methods, in which a part of evaporated atoms is ionized to deposit a film), but the latter method is particularly effective. According to this method, a very high film deposition rate can be achieved and it is suitable for mass production. However, as will be explained below, when a Co--Cr perpendicular magnetization film was actually fabricated by a vacuum evaporation method, various wrinkles occurred. 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 fl Co -Cr perpendicularly magnetized film by a vacuum evaporation method, the most excellent method is to carry out the evaporation while moving the substrate along the circumferential surface of a cylindrical can.

FIG. 1 is a front view of the interior of a conventional vacuum evaporation apparatus for producing a Co-(:r perpendicularly magnetized film).

A substrate 1 made of a polymeric material runs along the circumferential surface of a cylindrical can 2. Reference numerals 3 and 4 denote a substrate inlet roller and a substrate outlet roller, respectively, which guide and run the tape-shaped substrate 1. 5 is a vapor deposition 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 input roller 3 travels along the circumferential surface of the cylindrical square can 2 as it rotates, and is wound up by the substrate output roller 4: 9. You will be guided to the side. Note that the temperature of the circumferential surface of the circular and cylindrical can 2 can be arbitrarily set to around 350C. The evaporation source 5 heats and evaporates the Co--Cr alloy ingot, and only the evaporated atoms having a component close to normal incidence on the shielding plate 6 adhere to the substrate 1 made of a polymeric material 9, resulting in Co
- Form a Cr perpendicular magnetization film.

However, when a Co--Cr perpendicular magnetization film is manufactured with the above configuration, the following problems occur. That is, Co −
When a signal is recorded and reproduced in a perpendicularly magnetized Cr film, a film having a large coercive force Hc in the direction perpendicular to the film surface can obtain a high reproduction output. The holding force HO increases as the substrate temperature Tsub during vapor deposition increases. In order to put a Co-Cr perpendicularly magnetized film into practical use, a coercive force of at least 4000e is required.
As a result of experiments, it became clear that the temperature must be kept above 20℃. More preferably, the holding power Hc soil is 8
A film having a value of 000e or more is required, but in this case, the substrate temperature T8ub during vapor deposition must be 200° C. or more.

Note that the substrate temperature Tsub during vapor deposition mentioned here refers to the ambient temperature of the cylindrical can. In addition, the substrate 1 made of a polymeric material has surface properties and stability.

From the viewpoint of mass production, polyethylene terephthalate film or I-lyamide film is suitable.

However, using these films, the temperature of the circumferential surface of the cylindrical can 2 was increased to 120°C by the method shown in Figure 1.
If vapor deposition is performed as described above, wavy wrinkles will occur in the vapor deposited area.

FIG. 2 is a three-dimensional diagram showing the state in which wavy wrinkles are generated on the substrate 1 at this time, and 7 shows the wavy wrinkles. It has been revealed that such wavy wrinkles 7 occur in the vapor deposition part when the contact between the cylindrical can 2 and the substrate 1 is insufficient. Therefore, one idea to prevent this is to form a conductive film on the substrate 1 made of a polymeric material, create a potential difference between the conductive film and the cylindrical can 2, and bring them into close contact by electrostatic attraction. It will be done. 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 view 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 wrinkles 7 as shown in FIG. 2 disappear, but random wrinkles 9 are generated 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, since the cylindrical can 2 is at a high temperature, 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 apparatus is almost the same as that shown in FIG. 3, but the difference in FIG. 4 is that the substrate entrance roller 3 is replaced with a nip roller 3'. The surface of the nip roller 3' is generally made of comb. The substrate 8 made of a polymer material and having a conductive film formed on its surface is pressed against the cylindrical can 2 when it starts to come into contact with the cylindrical can 2. However, even with this configuration, when the temperature of the cylindrical can 2 is increased and a voltage is applied between the substrate 8 and the cylindrical can 2 to produce a Co-Cr perpendicularly magnetized film, the substrate 8 is moved to the cylindrical can 2. deformation occurs due to rapid heating when it comes into contact with the material, and before this deformation is corrected, it is pressed down by the nip roller 3', resulting in creases 10.

As described above, the conventional structure had the problem that wrinkles were generated on the substrate made of polymer material when the Co-Cr perpendicular magnetization film was deposited, making it unusable as a magnetic recording medium. .

(Objective of the Invention) The present invention solves the above-mentioned problems, and aims to provide a method for manufacturing a good perpendicular magnetic recording medium without wrinkles.

(Structure of the Invention) The present invention is directed to 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 120°C or higher. When forming a perpendicularly magnetized film containing Cr as a main component by a vacuum evaporation method, in a portion where the substrate is in contact with the cylindrical can, a contact start portion of the substrate with the cylindrical can and the vapor deposited film are formed. The cylindrical can and the conductive film are made to have approximately the same potential at a portion rearward of the position between the forming portion, and the cylindrical can and the conductive film are placed at a different potential at a portion forward of the position. A perpendicular magnetic recording medium without wrinkles can be obtained by using the method of the present invention.

(Description of Examples) FIG. 5 is a front view of the inside of a vacuum evaporation apparatus for explaining an example of the manufacturing method of the present invention.

In the figure, the cylindrical can 2 and the substrate entry roller 3 are grounded. Further, the substrate output roller 4 is connected to a power source 11 in order to create a potential difference between the cylindrical can 2 and the conductor portion on the surface of the substrate 8, which is made of a polymeric material with a conductive film formed on the surface. There is. Note that the potential of the substrate output roller 4 may be positive or negative, or may be alternating current. The substrate 8 begins to contact the cylindrical can 2 at the location indicated by arrow 12 and leaves at the location indicated by arrow 13. The former location is called the contact start part, and the latter is called the contact end part, and between the two parts, it is in contact with the 8-board cylindrical can. 14 is the deposited film forming part, where Co -
A Cr perpendicular magnetization film is formed.

Reference numeral 15 denotes a metal roller with a ground potential, which is provided between the contact initiation section 12 and the deposited film forming section 14, and is brought into contact with the conductive film on the surface of the substrate 80.

By arranging as described above, the cylindrical can 2 and the conductor film are at almost the same potential at the rear part of the metal roller 15, and the cylindrical can 2 is at the same potential at the front part of the metal roller 15. and the conductor film have different potentials. Note that the position of the metal roller 15 also refers to the rear part as indicated by the arrow j2.
On the side, the front part is indicated by arrow 13.

Next, the operation of the vacuum evaporation apparatus configured as described above will be explained. The board 8 is connected to the cylindrical can 2 at the part indicated by the arrow 12.
The conductor film on the substrate 8 and the cylindrical can 2 are at almost the same potential between this part and the part in contact with the metal roller 15, so no force acts between them. Therefore, random wrinkles as shown in FIG. 3 do not appear.

In front of the metal roller 15, the conductive film on the substrate 8 is connected to the power source 11.
Since a voltage is applied to the cylindrical can 2, an electrostatic attraction force 2 acts between the cylindrical can 2 and the conductor film on the substrate 8, and the substrate 8 is stretched onto the cylindrical can 2.

In the conventional method shown in FIGS. 3 and 4, when the substrate 8 comes into contact with the cylindrical can 2, the substrate 8 is rapidly heated and deformed, and before this deformation is corrected, the cylindrical can However, in the present invention, between the time when the substrate 8 comes into contact with the cylindrical can 2 and the metal roller ]5, the substrate 8 and the cylindrical can 2 are in close contact with each other. Since no force outside the blade due to the tension of the base plate 8 is acting between the base plate 8 and the base plate 8, the base plate 8 can move almost freely on the cylindrical can 2. That is, when the substrate 8 begins to come into contact with the cylindrical can 2, the substrate 8 undergoes rapid thermal deformation, but during this deformation, a strong force such as electrostatic attraction acts between the substrate 8 and the cylindrical can 2. The heat deformation ends without generating random wrinkles or creases. In front of the metal roller 15, the substrate 8, which has completed thermal deformation, is stretched against the cylindrical can 2 by electrostatic attraction. Therefore, no wrinkles occur when it is attached to a cylindrical can. In the vapor deposition film forming section 14, the substrate 8 is stretched to the cylindrical can 2 due to the electrostatic attraction between the conductor film on the substrate 8 and the cylindrical can 2, as shown in FIG. There are no wavy wrinkles. Thus, according to the method of the present invention, wrinkles are not generated at all.

Note that the specific voltage value of the power source 11, the distance between the contact initiation part 12 and the metal roller 15, etc. depend on the diameter and temperature of the cylindrical can 2, the width and thickness of the substrate, the thickness of the conductive film on the substrate, etc. Very different. - As an example, the diameter of the cylindrical can is 50cr+
+, temperature 250℃, substrate width and film thickness 15% each
Conductor film on 6n and 12μm 1 substrate with film thickness 3 o, o
When using OX permalloy, the voltage of power supply 11 is 10~
150V, the distance between the contact start part 12 and the metal roller 15 is 8
~40crn, a long Co-C with no wrinkles
A stable r-perpendicular magnetic recording medium was obtained.

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

A film with a thickness of 2000 x
A permalloy film of 1,000 mm thick is deposited on top of that
A Co--Cr perpendicular magnetization film of X was deposited.

However, no vapor deposited film was formed on 1 cm of both ends in the width direction of the film having a width of 15 cyn as margin parts. That is, the width of the deposited film is 13 cfn. - When depositing the gummalloy film, the temperature of the circumferential surface of the cylindrical can 2 with a diameter of 50 m was set at room temperature, so no wrinkles were formed. When further depositing a Co-'Cr perpendicular magnetization film on the Noguchi Malloy film, the temperature of the circumferential surface of the cylindrical can 2 was set to 260°C.
A voltage of -70 V was applied to the metal roller 4 by the power source 11. Further, the distance between the contact start portion 12 and the metal roller 15 was set to 13c1n. There were no wrinkles in the perpendicular magnetic recording medium after the vapor deposition was completed. Further, the He soil of the Co--Cr perpendicular magnetization film was 8500e, and exhibited excellent short wavelength recording and reproducing characteristics.

(Effects of the Invention) As explained above, according to the method of the present invention, wrinkles that conventionally occur when depositing a Co--Cr perpendicularly magnetized film on a substrate made of a polymeric material can be completely removed. 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 Co-Cr perpendicular magnetization film, and Figures 2 to 4 are three-dimensional diagrams for explaining 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 an embodiment of the manufacturing method of the present invention. 1.8... Substrate, 2... Cylindrical can, 3... Board entry roller, 4... Board exit roller, 5... Evaporation source, 6... Shielding plate, 7... ... Wavy wrinkles, 9... Random wrinkles, 10... Folding wrinkles, 11... Power supply, 12...
Arrow/contact start part, 13...Arrow/contact end part, 14
... Deposited film forming section, 15... Metal roller. Figure 1 Figure 2 Figure 1 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A perpendicularly magnetized film mainly composed of CO and Cr is placed on a substrate made of a polymeric material with a conductive film formed on its surface, which is running along the circumference of a cylindrical can heated to over 120°C. When forming a film by a vacuum evaporation method, in the part where the substrate is in contact with the cylindrical can, the position between the contact start part of the substrate with the cylindrical can and the vapor deposited film forming part is adjusted. A perpendicular magnetic recording medium characterized in that the cylindrical can and the conductor film are set at substantially the same potential at the rear portion, and the cylindrical can and the conductor film are set at different potentials at the front portion. Production method.