JPH02236822A - Production of magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a thin metal film type magnetic recording medium having excellent high-density recording characteristics.

Conventional technology Conventionally, coated magnetic recording media have been used, in which magnetic powder is coated on a non-magnetic substrate such as a polymer film, but in order to achieve higher recording density, a non-magnetic substrate A thin film type, in which a thin metal film is formed on top by a sputtering method or a vacuum evaporation method, is being put into practical use. Among thin film magnetic recording media, magnetic recording media in which a Co-based magnetic thin film is formed as a magnetic layer are attracting attention because of their excellent short wavelength recording characteristics.

Co-based magnetic thin films can be created by sputtering or vacuum deposition (including methods such as ion blating, which ionizes some of the evaporated atoms to deposit the film), but the latter method is particularly expensive. The deposition rate can be achieved and it is suitable for mass production.

A method for manufacturing a metal lotus film type magnetic recording medium by vacuum deposition using a polymer film as a non-magnetic substrate involves depositing a magnetic layer while running the polymer film along the curve of a cylindrical can. The best way to do this is to FIG. 4 schematically shows the internal structure of a vacuum evaporation apparatus using such a method.

The polymer film 1 runs along the circumferential surface of the cylindrical can 2. A magnetic layer is formed on this polymer film 1 by an evaporation source 5 . 3 and 4 are supply rolls or take-up rolls for the polymer film 1. As the evaporation source 5,
A resistance heating evaporation source, an induction heating evaporation source, an electron beam evaporation source, etc. are conceivable, but in order to evaporate the Co-based alloy, which is a high melting point metal, at high speed, it is necessary to employ an electron beam evaporation source. Incidentally, in the case of a large-scale evaporation source for mass production, a piercing type electron gun is generally used. 7 shows an electron beam generated by a Pierce type electron gun. Evaporation sI5
A shielding plate 6 is arranged between the can 2 and the cylindrical can 2 in order to prevent the vapor evaporated from the evaporation source 5 from adhering to unnecessary parts.

The shielding plate 6 is open as shown by S. The vapor that has passed through this opening S adheres to the polymer film I, forming a magnetic layer.

A thin film magnetic recording medium whose magnetic layer mainly consists of Co and Cr or Co and N1 and Cr is coated with Co and Cr or Co and N using a vacuum evaporation method using an apparatus such as the one shown in Fig. 4.
When 1 and Cr are evaporated from the same evaporation source, the following problems occur.

Since the vapor pressure of Cr is higher than that of Co or N1, the composition changes over time. That is, as shown in FIG. 5, a film containing a large amount of C1. is formed in the early stage of vapor deposition, and a film containing little Cr is formed in the latter stage. Co-Cr film and Co-Ni magnetic layer
In a -Cr film, the magnetic properties change if the composition of the film differs, so it is difficult to manufacture a long magnetic recording medium with uniform properties.

To solve this problem, Cr is supplied. Methods for supplying Cr include a method for directly supplying a Cr material to an evaporation source, and a method for supplying Co and Ni at the same time as Cr.

The feed material is in the form of a single element or an alloy, and is granular, rod-shaped, or plate-shaped.

Problems to be Solved by the Invention However, when a material is supplied into the molten metal in the high temperature molten state of the evaporation source, a bumping phenomenon occurs, and the scattered molten metal may reach the substrate and damage the substrate. Damage to the substrate is inconvenient because it causes dropouts during recording and reproduction.

The present invention aims to solve the problems of the prior art.

Means for Solving the Problems The present invention provides a thin-film magnetic recording medium whose main components are Co and Cr or Co, N1, and Cr by vacuum evaporation using an electron beam evaporation source. N1
When evaporating and Cr from the same evaporation source and continuously fabricating them on a moving substrate, the evaporation source is irradiated with a first electron beam and a second electron beam, and each electron beam is A partition wall is provided to prevent mixing of atoms evaporated from the irradiation area, and atoms evaporated from the first electron beam irradiation area are subjected to evaporation, and Cr, Co-Cr or Co is evaporated from one end of the second electron beam irradiation area. -Ni-Cr
This is a method of manufacturing a magnetic recording medium, characterized by supplying the following:

Effect: A bumping phenomenon is caused in advance by material supply in the second electron beam irradiation area, and the occurrence of a bumping phenomenon in the first electron beam irradiation area is suppressed.

Examples Examples of the present invention will be described below with reference to the drawings.

Embodiments of the present invention will be described using FIGS. 1 to 3.

FIGS. 1(a), (b), and (c) are schematic diagrams of an evaporation source in one embodiment of the present invention. 10 is a crucible, l4 is a molten metal, 15 is a supply material, 11 is a first electron beam, and 12 is a second electron beam. A partition wall l3 is provided to prevent evaporated atoms from the two electron beam irradiation regions from mixing. The first electron beam l1 is used for vapor deposition and is similar to the conventional one. The second electron beam 12 is not used for vapor deposition, but is used to actively cause the bumping phenomenon of the molten metal as the material is supplied. Here, the problem of bumping phenomenon will be explained. Although the cause is not clear, it is thought that impurity gases contained in the feed material or oxides particularly present on the surface of the feed material may be the cause. If impurity gas is present, it is considered that the feed material melts into the molten metal and simultaneously bumps and disappears in a relatively short time. On the other hand, in the case of oxides, it is unlikely that they themselves cause the bumping phenomenon. However, if oxides float on the surface of the molten metal and the floating particles are irradiated with an electron beam, which is a heat source, it can cause bumping. That is, a microscopic bumping phenomenon can be considered in which the oxide itself becomes hotter than the temperature of the surrounding molten metal and the molten metal in the immediate vicinity of the oxide is blown away. Furthermore, although this cannot be said to be a bumping phenomenon, it is also possible that the oxide is charged and scattered due to electron beam irradiation. In either case, the phenomenon occurs when the oxide is irradiated with an electron beam, and it is expected that it will take a considerable amount of time to disappear. In order to shorten this time delay, it is necessary to devise ways to increase the probability that floating oxides are irradiated with the electron beam. When the second electron beam l2 is scanned as shown in FIGS. 1(b) and 1(c), the probability that the floating oxide will be irradiated with the electron beam increases. Furthermore, as shown in FIG. 3, when a plurality of second electron beams 12 are irradiated, the probability of irradiating the oxide with the electron beam increases. Also, the third
As shown in the figure, it is also effective to narrow down the crucible using a shield 16 between a plurality of electron beam irradiation parts. Figures 2(a) and 2(b) schematically show the vacuum evaporation apparatus. FIG. 2(a) shows the case where either FIG. 1(a) or (b) is used as the evaporation source, and FIG. 2(b) shows the case when FIG. 1(c) is used as the evaporation source. The partition wall 13 prevents atoms evaporated by the second electron beam, oxides scattered, and molten metal from reaching the film forming portion.

A more specific explanation will be given below, taking the case of Co-Cr as an example.

Example 1 Co-Cr was deposited using the apparatus shown in Figure 2(a). As a board! @50cm, film thickness 8μ
A polyimide film of m was used. The running speed of the polyimide film was 50 m/min, and the film thickness was 200 nm.
- Cr film was deposited over 5000 m. still,
As the evaporation source, a polyimide film having a length in the width direction of 80 cm, a length in the running direction of the polyimide film of 15 cm, and a depth of 10 cm was used. The first electron beam 11 was generated using a Pierce type electron gun with an accelerating voltage of 30 kV, and the electron current was 3 A. The evaporation source 5 was scanned with a radiation of 50 cm s and a frequency of 600 Hz. The second electron beam l2 was generated using a Pierce type electron gun with an accelerating voltage of 30 kV, an electron current of 1 A, and no scanning was performed. The composition of the produced Co-Cr film was such that the Cr composition was within the range of 22 ± 0.3 wt% in the longitudinal direction from the initial stage to the final stage of vapor deposition, and a film that was stable over a long length and sufficiently usable for practical use was obtained. I found out that it was.

Example 2 Next, vapor deposition was carried out using FIG. 1(b) as evaporation-gE5. The second electron beam 12 was scanned at a frequency of 600 Hz in the 15 cm width direction of the crucible 10 with a radius of 10 cm. The rest is the same as in Example 1. The composition of the produced Co-Cr film was such that the Cr composition was within the range of 22 ± 0.3 wt% in the longitudinal direction from the initial stage to the final stage of vapor deposition, which was the same as that of Example 1.
Similarly, it was found that a film that was stable over a long length and was sufficiently usable for practical use was obtained.

Example 3 Next, as the evaporation source 5! Using figure (c), figure 2 (b)
) Vapor deposition was carried out using a vacuum evaporation apparatus shown in . The size of the evaporation source is such that the length in the width direction of the polyimide film is 6.
A 0 cms polyimide film having a length in the running direction of 30 cm and a depth of 10 cm was used.

The first electron beam l1 was generated using a Pierce type electron gun with an accelerating voltage of 30 kV, and the electron current was 5 A. The evaporation source 5 was scanned with a width of 50 cm and a frequency of 600 Hz. The second electron beam l2 is generated using a Pierce-type electron gun with an acceleration/acceleration voltage of 30 kV, and an electron current of 2 A.
Scanning was performed in the same manner as the first electron beam. The rest is the same as in Example 1. The composition of the produced Co-Cr film was such that the Cr composition was 22±0.2w in the longitudinal direction from the initial stage to the final stage of evaporation.
It was within the range of t%, and the navy blue formation was more stable than in Examples 1 and 2.

Example 4 Next, evaporation was performed using FIG. 3 as the evaporation source 5. Two second electron beams 12 were used, and each was scanned in the 15 cm width direction of the crucible 10 with a width of 10 cm and a frequency of 600 Hz. Each of the second electron beams 12 has an accelerating voltage of 3
The voltage was 0 kV and the electron current was 0.58. Others are Example 1
It is similar to The composition of the produced Co-Cr film was such that the Cr composition was 22±0 in the longitudinal direction from the initial stage to the final stage of evaporation.
．． It was found that the amount was within the range of 3 wt%, and as in Example 1, a film that was stable over a long length and was sufficiently usable for practical use was obtained.

Comparative Example Next, as a conventional example, vapor deposition was carried out using the apparatus shown in FIG. 2(a) without using the second electron beam 12 and the partition wall 13. That is, vapor deposition was carried out under substantially the same conditions as the conventional apparatus shown in FIG. 4, except for the material supply. Other conditions are the same as in Example 1. The composition of the produced Co-Cr film was Cr' in the longitudinal direction from the initial stage to the final stage of deposition.
It was found that the A composition was within the range of 22±0.3 wt%, and a stable film was obtained over a long length.

The Co-Cr films produced in the following four examples and one conventional example were slit into tapes with a width of 8 mm, and evaluated using a commercially available 8 mm deck. The evaluation item is dropout. Dropout was evaluated using a dropout counter, and the number of cases where the output decreased by 10 dB or more and the output decreased for 30 μs or more was measured. Table 1 shows the number of dropouts as an average per minute.

(The following is a blank space) As is clear from Table 1, the present invention has a significant improvement effect on the number of dropouts compared to the conventional example.
This result is considered to be the effect of suppressing the bumping phenomenon described above.

In the above specific examples, only Co--Cr was described, but the same applies to Co--Ni--Cr. Also, almost similar results were obtained using various feed materials. Furthermore, similar results were obtained even when a polymer film other than polyimide film was used as the substrate.

Effects of the Invention By using the manufacturing method of the present invention, it is possible to stably produce a long magnetic recording medium with little dropout and constant characteristics in the longitudinal and width directions by vacuum evaporation.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing an evaporation source used in a method of manufacturing a magnetic recording medium in an embodiment of the present invention, and FIG. 2 is a sectional view showing an evaporation source and a film used in a method of manufacturing a magnetic recording medium in an embodiment of the present invention. Cross-sectional view showing the outline of the positional relationship with the forming part, 3rd
4 is a sectional view schematically showing an evaporation source used in a method for manufacturing a magnetic recording medium according to an embodiment of the present invention; FIG. FIG. 5 is a graph showing the relationship between vapor deposition time and film composition when a long Co-Cr film is produced by evaporating Co and Cr from the same evaporation source without supplying Cr. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Cylindrical can, 3, 4... Supply roll or take-up roll, 5... Evaporation source, 6
... Shielding plate, 7... Electron beam, lO... Crucible, 11... First electron beam J1, 12... Second electron beam, l3... Partition wall, 14... Molten metal,
15... Supply material, l6... Shielding object, S...
Aperture. Name of agent: Patent attorney Shigetaka Awano (1 person) / θ l4 Figure

Claims (3)

[Claims] (1) A thin film magnetic recording medium containing Co and Cr or Co and Ni and Cr as main components is prepared using a vacuum evaporation method using an electron beam evaporation source.
When evaporating r from the same evaporation source and continuously fabricating it on a moving substrate, the evaporation source is irradiated with a first electron beam and a second electron beam, and each electron beam irradiation A partition wall is provided to prevent mixing of atoms evaporated from the region, and atoms evaporated from the first electron beam irradiation region are subjected to evaporation, and Cr, Co-Cr or Co- A method for manufacturing a magnetic recording medium, comprising supplying Ni-Cr. (2) The method for manufacturing a magnetic recording medium according to claim 1, characterized in that the second electron beam is scanned. (3) The method of manufacturing a magnetic recording medium according to claim 1 or 2, wherein the second electron beam is plural.