JPH02214014A - Thin-film magnetic disk and production thereof - Google Patents

Abstract

PURPOSE:To uniform the surface roughness of the disk, lower the coefft. of dynamic friction thereof, prolong the life and to improve durability and reliability by forming surface projections which are uniform in a circumferential direction at the time of forming an underlying metallic layer and a magnetic layer. CONSTITUTION:An Al substrate 1 subjected to electroless NiP plating is subjected to concentrical polishing according to the polishing grains to be used, by which the surface roughness is adjusted to 30 to 150Angstrom . The etching of the substrate surface is then executed by an inert gas and thereafter the continuous and uniform surface projections having about 200 to 400Angstrom height in the circumferential direction and >=30 pieces/mm sectional length density in the radial direction are formed by utilizing the growth of the underlying metallic layer 2 in the work hardened layer at both ends of the flaws generated during polishing at the time of forming the underlying metallic layer 2 and the magnetic layer 3 by a sputtering method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thin-film magnetic disk suitable as a recording medium and a method for manufacturing the same, and particularly relates to a thin-film magnetic disk that has improved durability by improving pre-treatment during manufacturing. This invention relates to a disc and its manufacturing method.

[Conventional technology] Conventionally, when manufacturing thin-film magnetic disks, the pretreatment method for the substrate is to take an AJ substrate whose surface is coated with an alumite layer, polish it to a mirror finish, and then
High frequency sputter etching is performed in an Ar, O2, or mixed gas atmosphere to form only recesses in the substrate.

The average surface roughness of this substrate is adjusted to 70 to 140. The conditions for selecting high frequency sputter etching conditions are gas pressure = 9 Pa, RF power density = 0.2 W/
cd.

and etching time=1 hour. After this, a thin film such as a magnetic layer is formed.

[Problem to be solved by the invention]

After mirror finishing, RF (high frequency) sputter etching
In a disk using a substrate with only recesses formed, the coefficient of dynamic friction is low in the initial state, but C8S (Contact
5tart 5top) When the test is repeated, the contact area increases due to wear except for deep recesses, and the frictional force increases.

A significant increase in adsorption power is observed. This allows the head,
There is a problem in that if the disks stick together, the protective layer, furthermore, the magnetic layer, etc., will be destroyed.

[Means to solve the problem]

In the present invention, A
1 substrate, and at least a base metal layer and a magnetic layer formed by a sputtering method, and by utilizing the scratches generated during the polishing process and the growth of the base metal layer in the process-altered parts at both ends, Approximately 200 to 400 people in height,
The above problems have been solved by providing a thin film magnetic disk manufactured by forming continuous and uniform surface protrusions with an actual cross-sectional density of 30 protrusions/fi or more in the radial direction, and a method for manufacturing the same.

〔Example〕

Regarding the thin film magnetic disk of the present invention and its manufacturing method,
This will be explained with reference to FIG. FIG. 1 is an enlarged partial sectional view of an embodiment of the thin film magnetic disk of the present invention. First, a /'l substrate (rNiP
(also referred to as "substrate") 1, depending on the abrasive grains used,
Concentric polishing process (texturing process) is applied,
The average surface roughness is adjusted to 30 to 150. After etching the substrate surface with an inert gas by high-frequency sputtering, the base metal layer 2 and magnetic layer 3 are formed by sputtering, and during polishing. The most important feature is that uniform surface protrusions are formed in the circumferential direction by utilizing the growth of the base metal layer 2 at the process-altered parts at both ends of the scratch.

Polishing can be performed using a polishing tape with abrasive grains of 1 to 10 μm, and the average surface roughness can be adjusted to 30 to 15 μm depending on the processing conditions.
It can be adjusted to 0 people. The purpose of this processing is to form irregularities on the substrate to reduce the contact area between the magnetic disk and the head, thereby reducing frictional force and adsorption force. However, since convex portions occur to the same extent as deep concave portions,
It is difficult to obtain uniform surface roughness. In addition, in a magnetic disk using a polished substrate with only concave portions formed by high-frequency sputter etching, long-term C8S tests showed large wear, increased frictional force and adsorption force, and increased friction between the head and the disk. If it sticks, protect it 14.
Furthermore, the magnetic layer 3 is destroyed. When high frequency sputter etching is performed using a NiP substrate 1 which has been subjected to concentric polishing to form moderate irregularities, tall protrusions are removed by etching.

Furthermore, when the metal H2 is formed by sputtering on the polished substrate l, the growth rate of the metal film 2 is faster in the paris parts at both ends of the scratch than in other flat parts, and the growth rate is 100%.
Continuous surface projections along the circumferential direction are formed with a width of about 0 to 2000. This is caused by active points in the processed parts, but when the oxide layer on the substrate surface is removed by high-frequency sputtering and etching, the areas where the metal film 2 grows at a high rate increase and the number of protrusions formed increases. The height of the protrusions can be adjusted depending on the thickness of the metal film 2 to be formed and the sputtering conditions, but in order to prevent long-term wear even in C8S tests, etc., and to prevent head crashes due to the low flying height of the head. The preferred range is 200 to 400 people.

In order to distribute the head load and keep the coefficient of dynamic friction low over a long period of time, the density of the surface protrusions must be at least 30 protrusions/m when the unit cross-sectional length is taken in the radial direction. On the other hand, in order to reduce the contact area with the head, the number should be at most 200 lines/fi. The length of the protrusion in the circumferential direction is not specified because it depends on the polishing conditions, and also depends on the sputter etching conditions and the underlying metal I! ! Since the sputtering conditions of No. 2 also depend on the equipment, they are not specified. However, if etching is performed excessively to remove the damaged parts, no protrusions will be generated.

In this way, by performing high-frequency sputter etching and adjusting the unevenness by polishing, it is possible to obtain surface protrusions of any desired height and density using the base metal WA2, and a highly durable thin-film magnetic disk can be produced. It becomes possible to do so. Hereinafter, a description will be given while showing specific examples and comparative examples with reference to FIG. 2 and subsequent figures.

<Example 1> A NIP substrate was polished using a polishing tape with an average abrasive grain size of 9 μm, and the average surface roughness was adjusted to 100.

Next, apply an RF output of 200 W and an Ar gas pressure of 10 m to this substrate.
High wave sputter etching was performed at Torr for 100 minutes.

While holding this substrate in vacuum, C was used as a base metal layer.
About 400 layers of R, about 700 layers of CO-based alloy as a magnetic layer, and about 400 layers of C (carbon) as a protective layer were formed by DC magnetron sputtering. Furthermore, F (fluorine)
A lubricant layer (5 in Figure 1) was created by spin-coding a lubricant based on
) and completed the magnetic disk. The radial surface shape of this disk is shown in FIG.

<Example 2> A NIP substrate was polished using a polishing tape with an average abrasive grain of 3 μm, and the average surface roughness was adjusted to 30.

Next, apply an RF output of 200W and an Ar gas pressure of 10mT to this substrate.
High-frequency sputter etching was performed for 2 minutes at Orr, and a thin film of the zero-order F-based lubricant was formed by sputtering in the same manner as in Example 1, and 20 people spin-coded it to produce a magnetic disk. The radial surface shape of this disk is shown in FIG.

Comparative Example 1 A NIP substrate was polished in the same manner as in Example 1, and high-wave sputter etching was performed at an RF output of 200 W and an Ar gas pressure of 100 m Torr for 300 minutes. Created.

The radial surface shape of this disk is shown in FIG.

Comparative Example 2> A magnetic disk was manufactured by subjecting a NiP substrate to the same polishing process as in Example 1, without performing high-frequency sputter etching, and in other steps similar to those in Example 1.

FIG. 5 shows the radial surface shape of this magnetic disk.

A C8S test was conducted on the above four types of magnetic disks. The results are shown in Table 1. The head used was a Mn--Zn ferrite head.

(Table 1) Note μ: Dynamic friction coefficient, c: Head crash
awe: average value, iax: fi large value From Table 1, it can be seen that the thin film magnetic disk of the present invention has a smaller dynamic friction coefficient μk than the conventional example (comparative example), and even when the number of C8S is significantly increased. It can be seen that they are stable over a long period of time and have high durability. The reason is,
As is clear from Figures 2 and 3, the disk has a nearly uniform surface roughness and a large number of surface protrusions of uniform height are continuously formed in the circumferential direction, resulting in an optimal surface shape. This is due to the fact that it was obtained. In a magnetic disk that has no surface protrusions and has mostly recesses, such as the comparative example shown in FIG. 4, the coefficient of dynamic friction gradually increases, causing destruction of the film (underlying metal layer 2 and furthermore, magnetic layer 3). Furthermore, a magnetic disk in which high protrusions of 500 Å or more are randomly formed, such as the comparative example shown in FIG. 5, is likely to cause head crashes due to surface protrusions, and appears to have a short lifespan.

〔effect〕

As explained above, according to the thin-film magnetic disk and its manufacturing method of the present invention, the surface roughness of the disk can be made uniform, and therefore the coefficient of dynamic friction is reduced, making it difficult to cause sticking between the disk and the head and a crash. It has excellent features such as significantly increased lifespan, significantly improved durability and reliability.

[Brief explanation of the drawing]

FIG. 1 is an enlarged partial cross-sectional view of one embodiment of the thin-film magnetic disk of the present invention, and FIGS. 2 and 3 show a first embodiment of the thin-film magnetic disk of the present invention. 4 and 5 are cross-sectional views showing the radial surface shape of the second embodiment. FIG. 7 is a cross-sectional view showing the radial surface shape of a thin film magnetic disk of a second comparative example. DESCRIPTION OF SYMBOLS 1...NIP board, 2... Base metal layer, 4... Protective layer, 5... Lubricating layer. 3...Magnetic layer, Patent applicant Representative of Victor Japan Co., Ltd. Umiki Japanese Procedural Amendment (voluntary) January 6, 1990 1. Display of the case 1999 Patent Application No. 34166 2. Name of the invention Thin film Magnetic disks and their manufacturing method 3, Relationship with the person making the amendment Patent applicant address 3-12-4 Moriya-cho, Kanayō-ku, Yokohama-shi, Kanagawa Prefecture Date of amendment order Voluntary amendment 5 Subject of amendment (1) Details "Disc" in the second line of page 5 of the book is corrected to "disk". (2) Insert the following phrase after "I will explain." on page 7, line 7. ``The measurements of the surface shapes of the magnetic disks shown in Figures 2 to 5 were carried out using a Talystep (Rank Taylor Hobson Co., Ltd., stylus shape 0.IX 2.5 μm).'' 43) Figures 2 to 5 are corrected as shown in the attached corrected drawings.

Claims (2)

[Claims] (1) It has at least an Al substrate that has been subjected to electroless Ni alloy plating, polishing with abrasive grains, and high-frequency sputter etching, and a base metal layer and a magnetic layer formed by sputtering. However, by utilizing the scratches generated during the polishing process and the growth of the base metal layer in the process-altered parts at both ends, the cross-sectional length density in the radial direction is approximately 200 to 400 Å in height and 30 lines/mm or more in the circumferential direction. A thin film magnetic disk characterized in that it is manufactured by forming continuous and uniform surface protrusions. (2) An Al substrate plated with an electroless Ni alloy is polished concentrically with abrasive grains, then etched by a high frequency sputtering method, and then at least the base metal layer and the magnetic layer are etched by a sputtering method. A thin film characterized in that it forms uniform surface protrusions that are continuous in the circumferential direction by using the scratches that occur during the concentric polishing process and the growth of the base metal layer in the process-altered parts at both ends of the scratches. A method of manufacturing magnetic disks.