JPS5885922A - Magnetic recording body - Google Patents

Abstract

PURPOSE:To improve an S/N ratio by providing a rhodium plating layer between a nonmagnetic substrate and a nickel alloy plating layer. CONSTITUTION:A rhodium plating layer 5 is provided on a nonmagnetic substrate 1 of an aluminum alloy, etc., and after a nickel alloy plating layer 2 is provided thereon, a magnetic thin film 3 consisting of a cobalt alloy plating layer is formed thereon and finally a protecting layer 4 is provided, whereby a magnrtic recording body for magnetic discs, etc. is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium such as a magnetic disk used in a magnetic storage device.

In recent years, a plated magnetic disk in which a magnetic thin film is produced by a plated method has begun to be used as a high-density magnetic recording medium.

When plating a magnetic thin film on this plated magnetic disk,
The magnetic properties and uniformity of the surface condition are strongly influenced by the underlying substrate, often leading to a decline in electromagnetic conversion characteristics.

In order to eliminate the influence of the base substrate and obtain a magnetic thin film with excellent magnetic properties and surface uniformity, a method has been used in which a nine-layer layer is provided between the magnetic thin film and the polished base surface.

Usually, the base substrate used is one obtained by applying nickel alloy plating to an aluminum alloy blank plate that has been cut after rolling, and then polishing this nickel alloy plating layer. Furthermore, a nickel-phosphorous plating film is often used as the intermediate layer formed on this layer, which reduces the sharp unevenness of the polishing path on the ground surface and contributes to improving the magnetic properties of the magnetic thin film formed thereon. are doing. However, since the nickel-phosphorus plating film is a nickel alloy plating film that has almost the same quality as the base polishing, it will continue to be affected by processing strains such as rolling and turning that the aluminum ζ alloy base plate undergoes, and the surface of the magnetic plating film will change. This affects the uniformity, that is, if the processing strain during rolling or turning is large, a significant decrease in 8/N will occur.

By the way, rhodium is known as a metal that blocks the effects of processing distortion as described above. However, when this is applied to the intermediate layer, a problem arises in that the magnetic properties of the magnetic thin film formed thereon are deteriorated, resulting in a significant decrease in output. That is, at present, no intermediate layer has been found that eliminates the influence of the underlying substrate and satisfies the requirements for both high output and low noise.

not present.

An object of the present invention is to improve these problems and provide a high-density magnetic recording body with high output and low noise.The magnetic recording body according to the present invention includes a non-magnetic substrate and a coating on this substrate. In a magnetic recording body consisting of a nickel alloy plated layer, a cobalt alloy plated layer covering the nickel alloy plated layer, and a protective film covering the cobalt alloy plated layer, a nonmagnetic substrate and a nickel alloy plated layer are It features a rhodium plating layer in between, which quickly eliminates the influence of the underlying substrate while maintaining the magnetic properties of the magnetic thin film, achieving low noise and high output.

Next, embodiments of the present invention will be described with reference to the drawings.

First, the characteristics of the magnetic recording medium of the wAK according to the present invention will be explained using comparative examples and examples.

Comparative Example 1 A donut-shaped disc was pulled out from a rolled aluminum alloy plate using a press, and the surface was flattened and smoothed by turning to produce an aluminum alloy blank. A nickel-phosphorus plating film having a thickness of 30 μm was formed thereon using an electroless nickel-phosphorus plating solution (manufactured by Nippon Kanigen Co., Ltd., Shime--v-BO). Both sides of this were mirror-polished by machining to obtain the non-magnetic substrate 1 shown in FIG. After forming the nickel alloy plated layer 2 of 0.1 m, a cobalt alloy plated layer 3 of 0.08 μm in thickness was formed in the plating bath shown below.

Plating bath cobalt sulfate 0.06mol//nickel sulfate
0.06mol//sodium hypophosphite 0.2
0 #Ammonium sulfate 0.10 #Sodium malonate 0.30 #Sodium malate
0.40 # pH-9, sodium disuccinate 0.50 # Bath temperature 80° C. Further, a protective film 4 with a film thickness of 0.1 μm was formed thereon.

The recording and reproducing characteristics of the thus obtained magnetic recording medium were measured under the following conditions, and the recording density was 630 FRPM (16
, 0OOFRPI)K had a reproduction output of 0.8 mVp-p, but 8o-, /N, pffI was 36 dB. When the magnetic properties of this magnetic recording medium were measured, H
e”61006.

Measurement conditions Disk rotation speed 3. ooorpm Track used: Diameter 125.6■ Head used Track width: 18.5 μm, gap length: 1 μm, number of coil turns: 16+16 Head flying height: 0.2 μm Recording current: 40 mAp-p Comparative Example 2 A magnetic recording medium was prepared using the same procedure as Comparative Example 1. However, in this comparative example, a nickel-phosphorous alloy plating layer 2 was formed on a non-magnetic substrate.
Instead, as shown in FIG. 2, a rhodium plated layer 5 with a thickness of 0.1 μm was formed using the following plated solution and plated conditions.
was formed.

Plating liquid dium plating solution Rh-221 (Japan Engelhard Co., Ltd.) Plating conditions Temperature 843°C Current density: 2 A/dn/ Plating time near 5 seconds Comparative example 1
When measured under the same conditions as 50-p/N, $37
Although the output was improved by dB, the output was significantly decreased to 0.45 mVp-p. When the magnetic properties of this magnetic recording medium were measured, it was found that He had decreased by 3500 eK.

A magnetic recording medium was produced in the same manner as in Example Comparative Example 1, but in this example, as shown in FIG. After forming a nickel alloy plating layer 2 of .3 μm, a cobalt alloy plating layer 3 was formed.

Comparative Example 1
When measurements were performed under the same conditions as in the comparison example, the 8o-p/Nrms was improved by 39dBK, and the output was also o, 8mV fl), the same value as the comparative example. When the magnetic properties of this magnetic recording medium were measured, the He value was 6050e, which was almost the same value as in Comparative Example 1.

As shown above in the comparative examples and examples, according to the present invention, a non-magnetic substrate, a nickel alloy plating layer covering this substrate, a cobalt alloy plating layer covering this nickel alloy plating layer, If a rhodium plating layer is provided between the non-magnetic substrate and the nickel alloy plating layer in a magnetic recording body consisting of a protective film covering the cobalt alloy plating layer, it will be possible to achieve an 8/8 N can be improved.

[Brief explanation of the drawing]

Figures 1 and 2 are Comparative Example 1 and Comparative Example 2, respectively.
FIG. 3 is a diagram showing a cross section of a magnetic recording body according to an embodiment of the present invention. 1...Nonmagnetic substrate, 2...Nickel alloy plating layer, 3...Cobalt alloy plating layer, 4
...Protective film, 5...Rhodium plated layer.

Claims (1)

[Claims] A nonmagnetic substrate, a nickel alloy plating layer covering the substrate, a cobalt alloy plating layer covering the nickel alloy plating layer, and a retention film covering the cobalt alloy layer. 1. A magnetic recording body comprising a rhodium plating layer between a nonmagnetic substrate and a nickel alloy plating layer.