JPH0526249B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a magnetic recording medium in which a magnetic layer containing Co and Cr as main components is formed on a substrate made of a polymer material, and its purpose is to improve the running properties of the magnetic recording medium. Windability,
The present invention provides a manufacturing method that prevents the occurrence of curls that adversely affect magnetic head touches and the like. Conventionally, as a magnetic recording medium, a coated medium in which magnetic powder is coated on a non-magnetic substrate has been used.
Currently, there is a trend toward smaller size and higher density of magnetic recording/reproducing devices, but there is a limit to the higher density of coated media. Thin film media made of ferromagnetic metal thin films are attracting attention as a media that exceeds this limit. Thin film materials mainly composed of Co are
It is the best because it has a large magnetocrystalline anisotropy energy due to the hcp structure of Co. Especially Cr
A Co--Cr film containing 10 to 30% by weight can be a perpendicularly magnetized film with excellent short wavelength recording and reproducing characteristics. Also Cr
A Co-Cr film containing 10 to 30% by weight also has excellent corrosion resistance. In other words, a magnetic recording medium whose magnetic layer is a Co-Cr film containing 10 to 30% by weight of Cr is practical and has very excellent short wavelength recording and reproducing characteristics.
It can be said to be an ideal thin film medium. Methods for producing thin film media made of ferromagnetic metal thin films include plating methods, sputtering methods, and vacuum evaporation methods, but the vacuum evaporation method is the best in terms of mass productivity. In order to form a thin film medium with good productivity and stability using the vacuum evaporation method, as shown in FIG. Vapor deposition may be performed while moving in the direction of. Note that 3 and 4 are a supply roll and a take-up roll for the substrate 1, respectively, and 5 is an evaporation source. However, when a thin film is formed by the above method, it generally curls in such a way that the ferromagnetic metal thin film 6 is on the inside or outside as shown in FIGS. Easy to take,
A problem arises in that magnetic head touch etc. deteriorate. Hereinafter, the states shown in FIGS. 2a and 2b will be referred to as normal curl and reverse curl, respectively. In order to use it as a magnetic recording medium, it is necessary that (Io-I)/Io be 4% or less. However, I is the length in the curled state as shown in Figure 2 a and b,
Io is the length without curls. In order to satisfy the above conditions, it is necessary to form a non-magnetic layer 7 on the side opposite to the ferromagnetic metal thin film 6 and a non-magnetic metal thin film 6 on the opposite side of the magnetic recording medium as shown in FIG. In this case, the substrate 1 may be shrunk by heat treatment after the thin film is formed, but in either case, at least one additional step is required. The method of the present invention optimizes the linear expansion coefficient of the substrate and the temperature of the can during evaporation without increasing the number of steps in a magnetic recording medium in which the magnetic layer is a film mainly composed of Co and Cr. By setting
(Io-I)/Io can be made 4% or less. The present invention will be explained below. A Co-Cr film containing 20% by weight of Cr was formed using the vacuum evaporation apparatus shown in Figure 1 by changing the linear expansion coefficient α of the substrate and the temperature T of the peripheral side of the can during evaporation, as shown in the table below. The experimental results of (Io-I)/Io in the curled state are shown below. However, the thickness of the substrate is 15μm, Co
-The thickness of the Cr film was 2000 Å.

[Table] Based on the results shown in the table, the linear expansion coefficient of the board is 1.0×
10 ^-5 to 2.5×10 ^-5 /℃, and when the temperature of the peripheral side of the can is 150 to 300℃, (Io-I)/Io
It can be seen that a film with 4% or less can be obtained. In addition
Even if the Cr composition of the Co-Cr film is changed from 10 to 30% by weight, even if substrates with thicknesses of 9 μm, 12 μm, 20 μm, and 26 μm are used, the film thickness of the Co-Cr film is changed in the range of 800 to 5000 Å. Even with this, the same results as above were obtained.
Furthermore, even if a base layer such as permalloy or Ti was provided on the substrate and a Co--Cr film was formed thereon, almost the same results as above were obtained. Regarding the above conditions, the reason why (Io-I)/Io is less than 4% is that the temperature of the peripheral side of the can is set to 150 to 300℃.
, Co-Cr is deposited on the thermally expanded substrate.
This is thought to be because the amount of shrinkage of the substrate and the Co-Cr film becomes about the same when the film is attached and the temperature drops after leaving the can. Next, embodiments of the present invention will be specifically described. Co-Cr containing 20% by weight of Cr having an axis of easy magnetization in the perpendicular direction of the film was produced using the vacuum evaporation apparatus shown in Figure 4.
A perpendicularly magnetized film was created. In the figure, 8 is a mask. A film with a thickness of 12 μm made of polyamide-based heat-resistant polymer material was used as the substrate 1, the traveling speed of the substrate 1 during vapor deposition was 10 m/min, and the thickness of the Co-Cr film was 2000 Å. temperature 230
The film was formed at ℃. Note that the linear expansion coefficient of this film is 1.6×10 ⁻⁵ /°C. The obtained magnetic recording medium has a positive curl, and its (Io−I)/
Io was 2%. As described above, in the method of the present invention, a magnetic layer mainly composed of Co and Cr containing 10 to 30% by weight of Cr is deposited on a substrate made of a polymeric material that is moved along the circumferential side of a cylindrical can. When forming the substrate by vacuum evaporation method, the linear expansion coefficient of the substrate is set to 1.0×10 ^-5 to 2.5×10 ^-5 /
℃, and the temperature of the peripheral side of the can is 150 to 300℃.
By setting , it is possible to obtain a magnetic recording medium with almost no curl.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main parts of a vacuum evaporation apparatus used for manufacturing magnetic recording media, Fig. 2 a and b are diagrams showing the curled state of the magnetic recording medium obtained by the vacuum evaporation method, and Fig. 3 4 is a diagram showing a magnetic recording medium in which curling is prevented by forming a thin film on the back surface, and FIG. 4 is a diagram showing essential parts of a vacuum evaporation apparatus used in an embodiment of the present invention. 1...Substrate, 2...Can, 5...Evaporation source, 8
……mask.

Claims (1)

[Claims] 1 A magnetic layer mainly composed of Co and Cr containing 70 to 90% by weight of Co is applied directly onto a substrate made of a polymeric material, or via an underlayer, along the circumferential side of a cylindrical can. When forming the substrate by vacuum evaporation method while running the substrate, the thickness of the substrate is 9 to 9.
26 μm, a coefficient of linear expansion of 1.0×10 ^-5 to 2.5×10 ^-5 /°C, a thickness of the magnetic layer of 800 to 5000 Å, and a temperature of the peripheral side of the can of 150 to 300°C. A method for manufacturing a magnetic recording medium.