JPS6035335A - Manufacture of flexible magnetic recording body - Google Patents

Abstract

PURPOSE:To obtain a recording body having negligible crack and curl and superior high-density characteristics by specifying the internal stress of a continuous thin film of magnetic iron oxide contg. Fe3O4 contg. optionally additives as the principal component during formation. CONSTITUTION:A magnetic film is formed on a polyimide substrate of 12.5mum thickness as a long-sized flexible substrate in a planar magnetron sputtering apparatus using Fe3O4 contg. 5wt% Co and 4wt% Cu as a target. A substrate sending and coiling mechanism is placed in the sputtering apparatus, and the long-sized substrate is sent along a water-cooled cylindrical cooling can to form continuously a magnetic film. A magnetic film having no internal stress (1<PAr <3X10<-3>Torr) does not cause crack and curl in a wide temp. range up to a temp. at which the thermal shrinkage of the substrate becomes remarkable, and it has superior flatness and surface properties. When the internal stress sigma is in the range of -3X10<9>dyne/cm<2> <sigma<2X10<9>dyne/cm<2>, curl is slightly caused, yet it is allowable in practical use.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a flexible magnetic recording medium used in a magnetic tape device or a flexible magnetic disk device.

Improving the recording density in magnetic recording devices is a constant trend in this industry, and in order to achieve this, it is essential to make magnetic recording bodies thinner and thinner.

Conventionally, as a medium, a so-called coating medium, in which a mixture of iron oxide fine particles and a binder is coated on an OJ flexible substrate, has been widely used. These recording media include magnetic tape for audio, magnetic tape for VTR, magnetic tape for computers, and flexible magnetic disks. Attempts are being made to increase the recording density by making the magnetic film thinner and increasing the coercive force of the medium. However, in coach ink media, it is extremely difficult to achieve uniform recording and reproducing characteristics when the thickness is less than several thousand. Therefore, as a high-density recording medium that can replace coating media, C is used as a continuous thin film medium that can be easily made thinner and has a higher coercive force.

Vapor-deposited tape or plated tape is attracting attention.

However, such a metal thin film is susceptible to damage and abrasion of the film surface and corrosion due to contact with a hard head such as ferrite, which poses a problem from the viewpoint of reliability of the thinner culm.

In order to solve this problem, the inventors of the present invention have developed an iron oxide magnetic thin film, γ-Fe20, which has good wear resistance and corrosion resistance, on a flexible substrate. Extracted from γ-Fe2O3 and Fe50. We have proposed a flexible magnetic recording material in which a continuous thin film of magnetic iron oxide is directly formed, the main component of which is an intermediate composition of
063665.56-064734, etc.) As a manufacturing method of this flexible magnetic recording material, "804
The process of forming a magnetic IC is to form a continuous magnetic iron oxide thin film mainly composed of an intermediate composition of Fe, 04 and r-J>'e203, and then thermally oxidize it.

Through this thermal oxidation process, γ-Fe2O3 or γ-F
e20. The most oxidized γ-Fe, 0
．． (Also, Fe50, which has a smaller crystal lattice spacing than Fe3O4, is formed in the base film.
Tensile stress was generated by the T, which caused curling and cranking of the magnetic film. As a result, the most basic properties of a flexible magnetic recording material, such as flatness and surface properties, were impaired and the material could not be used.

Therefore, the inventor filed a patent application No. 57-148984! Here, we proposed a method to achieve flatness of the recording medium by absorbing the yield of the Fe5 (4) film by thermal oxidation by the thermal contraction of the substrate. However, in this method, the substrate The thermal oxidation temperature was uniquely determined by the temperature of thermal contraction of the substrate, and the thermal oxidation temperature was determined to be the same as that of the magnetic film.

The present invention is an attempt to solve this problem, and its purpose is to achieve flatness without curling or cracking in a wide temperature range against thermal oxidation of a continuous magnetic iron oxide thin film formed on a flexible substrate. Superficiality 1? It is an object of the present invention to provide a method for manufacturing an XT-quality recording medium.

In the present invention, a continuous magnetic iron oxide thin film mainly composed of magnetite or magnetite containing additives is formed on a flexible substrate by sputtering using a magnetite sintered body as a target, and then this is oxidized to form y-Fe, 03 or r -Fe203 and Fes o, i''e at the time of formation, 0. Or the internal stress of a magnetic iron oxide continuous thin film mainly composed of Fe3O4 containing additives is -3XIO
dyne,/:rI to 2X10 dyne/cJ
The magnetic material formed in this range improves the flatness of the recording medium not only during formation but also through thermal oxidation over a wide temperature range from room temperature to the operating temperature of the substrate. Surface properties can be ensured, the product can be used satisfactorily even if curling occurs, and the thermal oxidation process can be significantly improved.

Specific examples of non-invention will be described below.

Example A long flexible substrate was made of magnetite (Fes Q4) K containing 5% Co and 4% Ou by weight on a polyimide substrate with a thickness of 125 μm. A planar magnetron sputtering device was used as a magnetic film forming device. (maximum magnetic field directly above the target ~5000e) was used.

A mechanism for sending out and winding up the substrate was provided in the spuck device, and a magnetic film was continuously formed on the elongated substrate along a water-cooled cylindrical cooling can.

Figure 1 shows the argon pressure (PA
r), the state of curls and cracks mf of the magnetic film mainly composed of FeBO4 formed on the substrate is shown by changing the sputtering force (FW). In the diagram, mark the presence or absence of cracks with ○ (
The state of the curl is expressed as (none), △ (slightly present), and × (many), and the curl condition is + (curl with the magnetic film on the inside), - (no curl), - (curl with the magnetic film on the outside). It was expressed as

The figure shows the state of curls and cracks in the magnetic film when it is annealed at a thermal oxidation temperature of 50° C. or higher for a magnetic film having an internal stress (σ) similar to Phr. As can be seen from the figure, the internal stress is O (1, <Phr <
3X10-3 Torr) has excellent flatness and surface properties without cracking or curling in a wide area at temperatures where thermal contraction of the substrate becomes noticeable (>~270℃), and its internal stress σ is -3X] C1dyne/J <σ<2X1
．． Although some curling occurred in the Odyne/crA range (excluding 0), it was within a practically acceptable range. The surface roughness l (+nax) of the thus produced recording medium was 400 A or less, which was better than the S surface roughness l (-max 800 to 1000 A) of the commercially available V'1' 1 cave.

The table shows the tape characteristics when illegal tape was actually applied to magnetic tape for VT and the recording density characteristics measured using a commercially available VTR device, as well as the results of a test using the same device and a commercially available V']' i
The results of the magnetic tape for T are shown below.

In the figure, the surface quality and flatness of the recording medium are the basics of recording.

Recording density I) that gives an output value of -6 dB of the solitary wave output value
Showed so. As shown in the table (the illegally produced magnetic tape had a high density characteristic that was twice as high as that of the commercially available magnetic tape, and its surface properties and flatness were also good). In the method for producing a flexible magnetic recording material according to the present invention, it is possible to produce a flexible magnetic recording material that is superior in high-density characteristics and has no problem with cracks or curls.

[Brief explanation of the drawing]

Figure 1 shows the state of curls and cracks in the magnetic film when the magnetic film is thermally oxidized corresponding to the internal stress of the magnetic film when the oxide magnetic thin film is formed by varying the sputtering power Pw and the sputtering pressure PAr7,2. FIG. Pw (KW)

Claims (1)

[Claims] A continuous thin film of magnetic iron oxide mainly composed of magnetite or magnetite containing additives is formed on a flexible substrate by target sputtering of magnetite (Fes04), and then this is oxidized to form gamma hematite (γ- A method for producing a flexible magnetic recording material forming a magnetic iron oxide continuous thin film mainly composed of Fe2O3) or an intermediate composition of comma hematite and magnetite, or containing additives therein, in which magnetite or 1. A method for manufacturing a flexible magnetic recording material, characterized in that the internal stress of a magnetic iron oxide continuous thin film mainly composed of magnetite containing additives is made to range from f -3X 109 dyne/cn to 2X10 dyne/-.