JPS60226023A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having a stable magnetic characteristic, uniformity and reproducibility by positioning magnetic poles of the same kind to face each other from the vertical direction of a substrate in the process of forming said substrate and forming a magnetic layer while moving the magnetic poles relatively in the horizontal direction of the substrate. CONSTITUTION:A magnetic field in a horizontal direction is generated by the repulsion of magnetic lines of force between the magnetic poles of the same kind when said poles are positioned to face each other. A magnetic plating stage is executed in such horizontal magnetic field, by which the magnetic layer is formed. Anisotropy in the horizontal direction is impressed in the deposition process in plating, by which the growth in parallel with the direction of the magnetic field is accelerated and the crystal grains slightly slender in parallel with the magnetic field are eventually formed. The crystal grains have nearly the state of the ideal needlelike single magnetic domain particles as the crystal grains are finer, thus resulting in increased Hc/Br. The improvement in the magnetic characteristic as a magnetic recording medium such as improvement in the squareness ratio and the consequent improvement in the recording and reproducing characteristics are attained. Not only the slenderer crystal grains are formed but also the magnetic characteristic for orienting the C-axis which is the direction of the axis of easy magnetization of the Co alloy more strongly in the magnetic field direction is improved and the variance thereof is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a high-density magnetic recording medium manufactured by a plating method used for magnetic recording bodies such as magnetic disks and magnetic drums.

[Prior art]

In recent years, recording media manufactured by plating have come to be used as high-density magnetic recording bodies.

The main reason why recording media produced using the plating method is expected to be used as high-density magnetic recording media is that the film thickness (δ) can be made thinner compared to conventional coating-type media. secondly, the residual magnetic flux density (Br) is large; and thirdly, it is easy to obtain an appropriate coercive force <sc).

The recording density and reproduction output obtained in magnetic recording media are
When using the same head, δ, Ec.

Determined by Br and t9, the following relationship is known.

(Recording density) α (B c / Br・δ) (Reproduction output) α (Br・δ・Ec) Since the coating type media requires the process of applying magnetic powder to the substrate together with the binder, the It is very difficult to control the film thickness to t-1μ or less. On the other hand, in the case of a plating type, it is relatively easy to obtain a film thickness of about 1 μm.

On the other hand, regarding Br, the plated type can obtain a value several times larger than the painted type, making it possible to increase the reproduction output.

Regarding Ec, apart from stability such as uniformity and reproducibility,
It is relatively easy to vary from 9300 oersted to about 800 oersted by changing the production conditions for ld and plating.

If δ, Br, and Re 'l can be manufactured with appropriate control and stability and reproducibility as a magnetic medium can be ensured, a magnetic recording medium produced by the plating method can be used as a high-density magnetic recording medium. It is an excellent thing.

However, when creating a magnetic tile using a plating method, it is said that it is not easy to form magnetic tiles with uniform magnetic properties and good reproducibility because of variations in various plating conditions, especially in Ha and δ.

The main reason for this phenomenon is that among the magnetic properties, Ec is sensitive to the structure of the magnetic film, and the fine structure of the magnetic layer is strongly influenced by the process of forming the magnetic film. The specific contents of the microstructure are the size of crystal grains and the state of distribution of nonmagnetic material that wraps around the grain boundaries. Plating is a series of interfacial reactions, and the fine structure of the magnetic film changes due to the effects of by-products and impurities as the plating progresses.
It appears as a change in c. Furthermore, the plating method has the disadvantage that the driving force for plating is based only on the difference in surface potential and is directly affected by subtle interfacial phenomena, making the resulting magnetic properties difficult to stabilize.

〔the purpose〕

The purpose of the present invention is to form a magnetic layer by plating,
The object of the present invention is to provide a magnetic recording medium with good uniformity and reproducibility by improving the drawback that the obtained magnetic properties are difficult to stabilize.

〔overview〕

The magnetic recording medium according to the present invention is formed by a plating method, and during the formation process, magnetic poles of the same type are opposed from above and below the substrate, and the magnetic layer is formed while moving the magnetic poles relatively in the horizontal direction of the substrate. It is characterized by the fact that it continues to form.

That is, when magnetic poles of the same type are placed opposite each other as shown in FIG. 1, a horizontal magnetic field is generated between them due to repulsion of magnetic lines of force. - The key point of the present invention is to perform the magnetic plating process in this horizontal magnetic field to form a magnetic layer.

During the magnetic plating formation process, when a horizontal magnetic field is present, horizontal anisotropy is applied to the precipitation process in the plating, promoting growth parallel to the direction of the magnetic field, resulting in slightly elongated crystals parallel to the magnetic field. Becomes grains. When the crystal grains become elongated, they approach the state of ideal acicular single-domain grains, which improves the magnetic properties of the magnetic recording medium, such as a larger Bc/Br and better squareness ratio, resulting in improved recording and reproducing characteristics. improves. Furthermore, not only the crystal grains become elongated, but also the O axis, which is the direction of easy magnetization of the Co-based alloy, is oriented more strongly in the direction of the magnetic field, so that the magnetic properties are improved and their variations are reduced.

〔Example〕

Non-magnetic electroless N1-P plating was applied to an aluminum substrate, which was precisely processed and used as a magnetic first and second substrate. As the magnetic pole, a rare earth magnet was used, which was joined to an iron yoke.

The number of magnetic poles was eight, and two pieces of magnetic poles were protected with polypropylene so as not to be covered with the plating solution, and the disk was sandwiched from above and below. The magnetic poles on the top and bottom of the woman were of the same type, and the disk tube was rotated at 120 times per minute during plating.

Magnetic plating FiOO-Ni-Pe was used. The plating conditions are shown below.

Bath composition Nickel sulfate mol/J Cobalt sulfate mol/J Sodium hypophosphite no. 1/J Sodium tartrate mol/J Boric acid mol/j Ammonium sulfate mol/j (P R9,0, liquid crystal 80°C) mo1/J 2nd The figure shows the structure of the magnetic pole used in this example.

1 is a magnetic pole composed of a rare earth magnet, 2 is an iron yoke, and 3 is a substrate.

The magnetic properties of the sample according to this example are the residual magnetic flux density (
Br) 8000 Gauss, coercive force (Ic) 650 Oersted, and squareness ratio (S) α82. For comparison, a sample prepared under the same plating conditions without applying magnetism*1 had no change in residual magnetic flux density (Br) and coercive force (Ec), and the squareness ratio (S) was α78. improved by 5 inches.

Furthermore, the dispersion of the coercive force (E) was halved, and the variation was reduced.

〔effect〕

As stated above, according to the present invention, magnetic properties such as squareness ratio are improved, and at the same time, variations in the magnetic properties are reduced.
It has become possible to ensure the stability and reproducibility of plated magnetic media. In the embodiment, the magnetic poles were constructed using permanent magnets, but similar effects can be obtained using electromagnets.

[Brief explanation of the drawing]

FIG. 1 is a diagram of lines of magnetic force generated when magnetic poles of the same type are opposed to each other. FIG. 2 shows the shape of the magnetic poles used in the example, where 1 is a rare earth magnet, 2 is a yoke, and 3 is a substrate. Goose 10't, 2rg (α) (b)

Claims (1)

[Claims] A magnetic recording medium formed using a plating method. During the formation process, magnetic poles of the same type are opposed from above and below the substrate.
A method of manufacturing a magnetic recording medium, comprising forming a magnetic layer while moving a magnetic pole in the horizontal direction of a substrate.