JPH06131648A - Magnetic recording medium - Google Patents

Abstract

(57) [Abstract] [Purpose] A double-layered magnetic film suitable for high density perpendicular magnetic recording such as a flexible disk (hereinafter abbreviated as FD) or tape that can be used for information recording equipment, audio or video equipment, etc. To obtain a recording medium. A magnetic recording medium having a non-magnetic material, a first magnetic layer containing Fe as a main component and a second magnetic layer containing Co—Cr as a main component, which is formed on the non-magnetic body. , First
A magnetic recording medium, wherein the magnetic layer simultaneously contains 1.0 to 3.0% by weight of Si and 10 to 20% by weight of Ni at the same time.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a magnetic recording medium. More specifically, the present invention relates to a double-layer magnetic recording medium suitable for high-density perpendicular magnetic recording, which is a flexible disk (hereinafter abbreviated as FD) or tape that can be used in information recording devices, audio or video devices, and the like.

[0002]

2. Description of the Related Art The perpendicular magnetic recording system is a magnetic recording system having excellent short wavelength recording characteristics. This is to magnetize the medium in the direction perpendicular to the film surface of the magnetic recording medium. Therefore, in this method, it is necessary to use a perpendicular magnetization film in which residual magnetization remains in the direction perpendicular to the medium surface. As the perpendicular magnetization film, cobalt (hereinafter abbreviated as Co) and chromium (hereinafter abbreviated as Cr)
The Co-Cr alloy film containing as a main component has excellent characteristics. On the other hand, in order to perform high-density recording using a main pole excitation type head, it is necessary to concentrate magnetic flux inside the Co—Cr alloy film, and therefore the backing layer (abbreviated as BL below) is required.
As a soft magnetic layer. Soft magnetic B. L. For this, permalloy (for example, an alloy of 80Ni + 20Fe in weight ratio) is used. Co-Cr alloy film has a thickness of 0.1 μm
m, soft magnetic B. L. It is 0.5 μm. Highest density recording is achieved with the above film thickness. A conventional perpendicular magnetic recording medium is a B.P.O. film on a substrate which is a heat resistant polymer material (for example, a polyimide film). L. As a permalloy layer having a thickness of about 0.5 μm, and Co--Cr as a perpendicular magnetization film formed on the permalloy layer.
The layer is formed to have a thickness of about 0.1 μm.

[0003]

However, as described above, the B. L. When the permalloy layer of 0.5 μm was formed, the following problems occurred. First, when a perpendicular magnetic recording medium is manufactured by the DC magnetron high-speed sputtering method, the film deposition rate is about 20Å / sec. On the other hand, in order to form permalloy of 0.5 μm, it is necessary to expose the substrate to plasma for about 250 seconds, which requires a long time for film formation, which makes it difficult to manufacture a medium at high speed. is there. The temperature of the substrate exposed to plasma for a long time becomes high, the coercive force of the formed permalloy layer becomes high, the magnetic permeability becomes small, and the soft magnetic property is lost.

Secondly, the combined metal thickness of the Co--Cr layer and the permalloy layer is 0.6 μm or more, which reduces flexibility when used as a tape medium, for example. Third
In addition, when a high-definition type tape is used, the amount of recording is large, so the amount of tape is long, and it is difficult to miniaturize the cassette tape when the medium is thick. Fourth, if high power is applied to increase the deposition rate simply to reduce the film forming rate of the permalloy layer, the coercive force of the permalloy layer increases.
Fifth, Fe as the first magnetic layer exhibiting excellent soft magnetic characteristics
If —Si or the like is used, a Co—Cr film formed on it cannot have good crystals, and is not suitable as a high recording density medium. The present invention has the above-mentioned problems, namely, B.
L. The object is to solve many problems caused by the permalloy and the Fe-Si layer.

[0005]

The features of the present invention for attaining the above object are that a non-magnetic substrate, a first magnetic layer containing Fe as a main component and a Co--C layer on the non-magnetic substrate.
In a magnetic recording medium having a second magnetic layer containing r as a main component, the first magnetic layer comprises 1.0% by weight to 3.0% by weight of Si and 10% by weight to 20% by weight. In a magnetic recording medium containing Ni.

The substrate of the magnetic recording medium may be a plastic film, a glass plate or the like. Specific examples of the plastic film include a polyimide film, polyethylene terephthalate (PET), and a polyamide film. When a material other than Fe is used as the main component for the first layer, the saturation magnetization density becomes small, and thus the B. L. It is necessary to thicken the film thickness, and if it is thinned, the reproduction output when recording and reproducing is small.

The weight ratio of Ni in the first magnetic layer is 1.0% by weight.
If it is less than 3.0% by weight, the soft magnetic property may be lost. If the content of Ni is less than 10% by weight and more than 20% by weight, the Co—Cr crystal of the second magnetic layer thereover is disturbed, resulting in a drawback that the reproduction output becomes small. The thickness of the first magnetic layer is preferably 0.1 μm to 0.4 μm,
If it is 1 μm or less, the reproducing voltage is too low, and if it is 0.4 μm or more, the flexibilization is impaired especially when a plastic film is used as the substrate of the magnetic recording medium. In addition, when the coercive force of the first magnetic layer is 100 Oe or less, the reproduction output becomes small.

[0008]

【Example】

Examples 1 to 3 Using a magnetron type DC sputtering device in a batch type sputtering device, the inside of the vacuum chamber was evacuated to a vacuum and the substrate was set to 20.
After heating to 0 ° C and degassing, before sputtering,
Exhaust to 3 × 10 ⁻⁷ Torr or less, heat the substrate temperature to 150 ° C., introduce high-purity argon gas, and use a polyimide film having a thickness of 40 μm for the substrate of the magnetic recording medium to obtain the composition shown in Table 1. An Fe-Ni-Si film is formed, and the substrate temperature is 150 ° C.
to form a magnetic recording medium. The electromagnetic conversion characteristics of the medium are cut out to a 3.5 inch floppy disk,
Disk evaluation device (main magnetic pole excitation magnetic pole head, main magnetic pole: CoZrNb (Bs = 125000 Gauss),
The main magnetic pole film thickness was 0.3 μm, the track width was 100 μm, the number of windings was 50 Turns, and the relative speed was 2 m / Sec).

Comparative Examples 1 to 4 Magnetic recording media shown in Table 1 were obtained in the same manner as in Example 1.
Also, the electromagnetic conversion characteristics of the medium were measured in the same manner.

[0010]

[Table 1]

[0011]

According to the present invention, the following effects have been confirmed. (1) B. L. Without impairing the effect of B.
L. The film thickness can be reduced. (2) B. L. It was found that the crystallinity of the Co-Cr layer formed on the above film is better than that formed on the conventional permalloy layer.
Therefore, when recording / reproducing, a high reproducing voltage can be obtained with a high recording density.

Claims (3)

[Claims] 1. A magnetic recording medium having a non-magnetic material, a first magnetic layer containing Fe as a main component, and a second magnetic layer containing Co—Cr as a main component, which is formed on the non-magnetic material. Okay,
A magnetic recording medium, wherein the first magnetic layer simultaneously contains 1.0 wt% to 3.0 wt% Si and 10 wt% to 20 wt% Ni in weight ratio. 2. The magnetic recording medium according to claim 1, wherein the coercive force of the first magnetic layer is 100 Oe or less. 3. The magnetic recording medium according to claim 1, wherein the first magnetic layer has a thickness of 0.1 to 0.4 μm.