JPS61145721A - Magnetic disk - Google Patents

Abstract

PURPOSE:To improve the electromagnetic characteristic and reliability on the head crash resistance of the titled disk by using a Cr-film ground substrate. CONSTITUTION:Since a hollow cathode vapor deposition process which is used in the formation of a film ground substrate made of Cr 2 is a kind of ion plating process, the deposition process can be performed in the order of an atom by using, for example, high purity Cr of 99.9% purity. Accordingly, the film substrate substantially without any defects can be obtained. A Cr-film substrate having 700-120kg/cm<2> Vickers hardness can be obtained by the hollow cathode deposition process, although the result depends largely on the conditions. Consequently, a surface which is simultaneously flat and smooth can be obtained by adopting and appropriate working process.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to improvements in magnetic disks.

[Background of the invention]

The base film substrate used in conventional magnetic disks is an alumite substrate, and since the hardness of this alumite substrate itself is about 400 kg/-, the film thickness is limited to 3 μm from the viewpoint of heat resistance. For this reason, the underlying film cannot provide sufficient support against collisions and loads from the head, resulting in a problem that magnetic disks using this film do not have sufficient head crush resistance.

On the other hand, as prior art, for example, Japanese Patent Application Laid-Open No. 49-74912
The purpose of this invention is to improve the corrosion resistance of recording media, and the content thereof is to improve the corrosion resistance of recording media.
, Cr, and (1) are formed by vapor deposition to a thickness of the base film of 0.2 to 0.3 μm. In such prior art, no consideration or investigation has been made from the standpoint of improving head crush resistance, and the film thickness is also formed to be thin as described above.

[Purpose of the invention]

In view of the above, an object of the present invention is to significantly improve the performance of a magnetic disk by improving electromagnetic conversion characteristics and reliability against head crushing.

[Summary of the invention]

In order to achieve the above object, the present invention provides a magnetic disk constructed by sequentially laminating a base film, an iron oxide magnetic thin film, and a protective film on an M alloy base material, in which a substrate is formed using Cr metal as the base film. It is characterized by what it did.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, 1 is 508 containing 4.5% Mf.
A base material made of 6M alloy, this base material 1 has a surface roughness of α1
Plate thickness (t) t9 M after finishing μmRynax
Outer diameter 210φ and inner diameter 100φ due to alloy material (not shown)
K is formed. 2, after performing necessary degreasing and etching treatment to clean the surface of the M alloy base material 1,
This is a base film substrate set in a hollow cathode deposition apparatus (not shown) and formed with Cr to a thickness of 90 μm under the following conditions.

Degree of vacuum (operating pressure) 7.5x10″Toff Substrate temperature 200°C Substrate bypass surface pressure -5OV Amount of Ar gas introduced into the hollow cathode discharge tube 30C Si film formation time 20 minutes A Cr base film was formed under the above conditions. Thereafter, the surface is polished to a surface roughness of 0.04 .mu.m and the thickness of the Cr underlayer to 7 .mu.m, thereby completing the underlayer substrate.

After cleaning and cleaning the Cr polished surface of the substrate 2, decomposed iron (Fe3) was deposited on the substrate 2 under the following sputtering conditions.
O4) Thin film 3 is formed.

Vacuum degree 10wx Tr)rr atmosphere
kr-5%0°Substrate heating temperature 200°C Target Fe-2,0%C.

Target input power density 6”/cyd Thickness α20μm Film formation time
After forming the Fe50+ thin film 3 as described above for 12 minutes, the disk was placed in a thermal oxidation furnace and converted into r-Fe and OB by treatment at 300°C and 5Ar. Further, on this iron oxide magnetic thin film 6, a protective film (lubricating film) 4 of fluorocarbon thread is formed.

Next, the present embodiment configured as described above, particularly the characteristics of the CrH base film substrate 2, will be explained.

The hollow cathode evaporation method used to form the Crg base film substrate 2 is a type of ion plating, so if high purity, for example 929% Cr, is used as the evaporation material, the The base film substrate is virtually defect-free. In addition, according to the hollow cathode deposition method, it is possible to coat a Cr base film substrate with a Vickers hardness of 700 to 1200 to /-, depending on the conditions, so that it can be made essentially flat and smooth by adopting an appropriate processing process. It is possible to walk around the surface.

As mentioned above, the Cr base film substrate 2 has a relatively high hardness (H
V700-1200 "4/-), it can become a strong base against head collisions and loads. However, if the film thickness is 5 μm or less, the M base material is soft (Hv = 60 ~
909), the Cr base film substrate 2 cannot exhibit sufficient effects. On the other hand, if the film thickness exceeds 15 μm, not only the effects of increasing the film thickness will not be exhibited, but also the problem of cracks in the base film itself will occur, which is not preferable. Therefore, in this example, Cr
The film thickness of the base film substrate was limited to 5 to 15 μm.

Furthermore, in a so-called sputter disk in which iron oxide is formed by reactive sputtering as in this embodiment, if a chemically unstable metal such as an A7 substrate or an NL-P plated substrate is used as the base film, the oxygen of the iron oxide is incorporated into the underlying film, making it impossible to form an iron oxide medium with excellent performance. However, if a Cr undercoating film substrate is used as in this embodiment, there is no fear of the above problem and the chemical stability in relation to the medium is excellent. This is considered to be because a strong chromium oxide film is formed on the surface of chromium itself.

According to this example, by using a Cr base film substrate, it was possible to achieve a C8S resistance of 20,000 times, whereas in this example, the C8S resistance of the conventional example using an alumite base film substrate was 20,000 times. There is a disadvantage that it is significantly lower (about 1 to 2 digits) than that of (20.0 hits).

〔Effect of the invention〕

As described above, according to the present invention, by using a Cr base film substrate, electromagnetic conversion characteristics and head crush resistance reliability can be improved. therefore,
It is possible to significantly improve the performance of magnetic disks.

[Brief explanation of drawings]

The drawing is a sectional view showing an embodiment of the magnetic disk of the present invention. DESCRIPTION OF SYMBOLS 1... M alloy base material, 2... Cr base film substrate, 3... Iron oxide magnetic thin film.

Claims (1)

[Claims] 1. A magnetic disk constructed by sequentially laminating a base film, an iron oxide magnetic thin film, and a protective film on an Al alloy base material,
A magnetic disk characterized in that a substrate is formed using Cr metal as the base film. 2. The magnetic disk according to claim 1, wherein the Cr base film substrate has a thickness of 5 to 15 μm. 3. The magnetic disk according to claim 1 or 2, wherein a hollow cathode deposition method is used to form the Cr base film substrate.