JPS62146434A - Magnetic disk - Google Patents

Abstract

PURPOSE:To improve durability without deteriorating the electromagnetic conversion characteristic of a medium by providing approximately concentrical grooves on the surface of a substrate on the side where a magnetic layer is formed or on the surface of an underlying layer provided thereon. CONSTITUTION:A magnetic disk 1 has the underlying layer 3 on the nonmagnetic substrate 2 and has usually an intermediate layer 4 consisting of a nonmagnetic metal on the underlying layer 3 and a thin magnetic metallic layer 5 thereon. A protective film 6 consisting of a nonmagnetic metal, a carbon protective film 7 and a top coat layer 8 are successively laminated on the magnetic layer 5. Al or Al alloy is preferably used as the nonmagnetic substrate 2 and is formed to a disk shape having preferably 1.2-1.9mm thickness. A layer contg. compsn. such as Ni-P or Ni-Cu-P is formed by an electroless plating method, etc., as the underlying layer 3. The underlying layer 3 is formed to 3-50mum film thickness and the grooves 9 which are approximately concentrical and have the distribution and depth irregular in the diametral direction are provided on the surface thereof to about 0.001-0.2mum depth. The attraction characteristic and durability are thereby improved without deteriorating the electromagnetic conversion characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to improvements in the adsorption properties, durability, and other characteristics of so-called hard type magnetic disks.

Prior art and its problems Magnetic recording media used in magnetic disk devices are generally called magnetic disks or disk media, and their basic structure includes a donut-shaped substrate and magnetic layers usually placed on both sides of the substrate. ing.

There are two types of substrate materials for such recording media: hard materials such as aluminum alloy, and plastic materials such as Mylar, which are the same as magnetic tape media.Generally, the former is called a hard type magnetic disk, and the latter is called a flexible disk. I'm calling you V.

By the way, the heart-type WL disk uses a floating magnetic head, and a large impact is applied to this head during contact, start, and stop, and the durability and abrasion resistance of the head against mechanical contact with the magnetic head are affected. It has been pointed out that there is a problem with adsorption etc.

Conventionally, these problems have been thought to be mainly caused by various physical properties of the media surface, and various proposals have been made to provide a protective film as the top layer of these media.

For example, examples of inorganic protective films include Rh, Cr (Japanese Patent Publication No. 52
-18001 Publication No. 11i) Ni-P (Special Publication No. 18001-11i)
No. 726), as well as Re%Os, Ru, Ag%
Au, Cu.

Pt, Pd (Special Publication No. 57-6177), N1-
Cr (Japanese Patent Publication No. 57-17292) etc. are used,
On the other hand, solid lubricants include inorganic or organic lubricants,
For example, silicon compounds such as 5i02, Sin, Si
3 N4, etc. (Japanese Patent Publication No. 54-33726), polysilicic acid or silane coupling agents, such as tetrahydroxysilane, polyaminosilane, etc., Japanese Patent Publication No. 59-398
No. 09) and car phones are used.

However, the materials and structures of these conventional protective films provided on the magnetic layer do not improve the durability, abrasion resistance, or
No material has been developed that has sufficiently high weather resistance, corrosion resistance, etc., and does not cause the so-called adhesion phenomenon in which the head sticks to the surface of the medium.

Therefore, in order to address these problems, the present inventors have proposed that the medium structure has a carbon protective film on the magnetic layer, and a top coat film containing a predetermined compound is formed on top of the carbon protective film. (Japanese Patent Application No. 60-289010, which is the original application of this application, etc.).

According to this proposal, the durability, abrasion resistance, weather resistance of the media,
Corrosion resistance, adsorption, etc. are greatly improved, but in order to further improve these characteristics, especially adsorption characteristics and durability, and to obtain a medium with stable output, error-free, and excellent electromagnetic conversion characteristics, it is necessary to It is necessary not only to treat the surface of the medium in various ways, but also to reconsider the treatment and form of the substrate surface of the medium.

■ Purpose of the Invention The purpose of the present invention is to create a magnetic material that does not deteriorate the electromagnetic conversion characteristics of the medium, has excellent durability, abrasion resistance, weather resistance, corrosion resistance, etc., has no head adhesion, and has extremely high reliability in practical use. The goal is to provide discs.

■Disclosure of the Invention These objects are achieved by the present invention described below.

That is, the present invention provides a magnetic disk in which a metal thin film magnetic layer is present on a disk-shaped and rigid non-magnetic substrate. This magnetic disk is characterized by having substantially concentric grooves.

(1) Internal Structure of the Invention From 1 to 5, the specific structure of the present invention will be explained in detail.
FIG. 1 shows an embodiment of the magnetic disk of the present invention.

The magnetic disk 1 of the present invention generally has a base layer 3 on a non-magnetic base 2, a reverse-shaped non-magnetic metal intermediate layer 4 on the base layer 3, and a metal thin film magnetic having layer 5;
Generally, a nonmagnetic metal protection film 7, a carbon protection film 7, and a top coat layer 8 are sequentially laminated on the magnetic layer 5.

Examples of the material of the nonmagnetic substrate 2 used in the present invention include metals such as aluminum and aluminum alloys, glass, ceramics, and engineering plastics. Among these, it is preferable to use aluminum, aluminum alloy, etc., which have good mechanical rigidity, workability, etc., and can easily form a base layer, which will be described later.

The thickness of such a non-magnetic substrate 2 is 1.2 to 1.91I1
m, and its shape is disk-like.

In particular, when a metal substrate such as A2 is used as the material of the non-magnetic substrate 2, it is preferable to provide the underlayer 3 on this substrate. This base layer 3 is made of N i-P,
It is formed by containing any one of the compositions such as N1-Cu-P, N1-W-P, and N1-B. This film is preferably formed by a liquid phase plating method, particularly an electroless plating method. According to the electroless plating method, an extremely dense film can be formed, and mechanical rigidity, hardness, and workability can be improved.

In addition, the composition ratio (wt) of the base layer consisting of the above composition is:
It is as follows.

That is, (N i x Cuy)A Pa(N i x
W'j) APa In these cases, x:y=100:0-10:90, A:B=97:3-85:15.

In the case of N1xBy, x:y=97:3 to 90:3.

To briefly describe an example of the process of this electroless plating method, first, alkaline degreasing and acid degreasing are performed, followed by several zincate treatments, and after surface adjustment with sodium bicarbonate, pH 4, Plating may be carried out in a 0-6.0 nickel plating bath at about 80-95°C for about 0.5-3 hours.

These plating treatments are, for example,
No. 50-1438, Japanese Patent Publication No. 50-1438, etc.

The thickness of such base layer 3 is 3 to 50 μm, particularly 5 to 2 μm.
0 μl is preferred.

In the present invention, the surface of the base layer 3 is provided with grooves 9 that are substantially concentric and have irregular distribution and depth in the radial direction.

Such concentric irregular grooves 9 are formed, for example, in the base layer 3.
For example, a polishing chip coated with an abrasive can be pressed while rotating the disc-shaped base coated with the abrasive. Further, when the base is rotated, the polishing chive can be oscillated in the radial direction of the disk-shaped base to apply so-called oscillation, thereby making the concentric circles slightly irregular or oscillating.

The depth of the groove 9 formed in this way is 0.00
It is about 1 to 0.2 μI. Furthermore, the number of grooves 9 is 400 to 1600 per unit length in the radial direction of the base material.
! It is about 1.

When forming such a groove 9, the process conditions are usually
Work rotation speed 50 to 1000 times/min, contact pressure O
~5 Kg/CJ, Ossi 9520~120 times/
minute, and the oscillation width is approximately 0 to 100 mm.

By providing such concentric irregular grooves 9, the adsorption characteristics and durability are improved without deteriorating the electromagnetic conversion characteristics.

Note that if the grooves are provided in one direction, the effects of the present invention will not be achieved.

In addition, when the base layer 3 is not provided on the base 2F, the above-mentioned groove 9 may be provided directly on the base 2F.

Furthermore, a metal thin film magnetic layer 5 whose L component is Co or one or more of Co, Ni, Cr, and P is formed on the body which may have such an upper layer 3.

A specific example of the composition of this product is Co-Ni%Co-
Ni-Cr, Co-Cr, Co-N1-P, Co-Zn
-P, Co-Ni-Mn-Re-P, γ-Fe2O3, etc. Among these, especially Co-Ni, Co-Ni
-Cr, Co-Cr, Co-N1-P, etc. are preferred,
The preferred composition ratio of these alloys is the weight ratio, Co:N1=1
: 1~9: 1, x:y=x in (CoNi)CrB
yA 1:1-9:1, 8:B=99.9:0.1-75:2
5, co:Cr=723~9:1, (CoN1y)APB, x:y=1:O~1:9, 8:B=99.9:0.1~
It is 85:15. Outside these ranges, recording characteristics deteriorate.

Metal Thin II like this! The second magnetic layer 5 can be formed by various plating methods in the gas phase or liquid phase, but sputtering, which is one type of gas phase method, is particularly preferred. By using the sputtering method, a magnetic layer with good magnetic properties can be obtained.

In addition, the composition of the magnetic layer is the above-mentioned γ-Fe20. In this case, reactive sputtering using Fe as a target and reactive gas 02 or the like may be used.

Sputtering methods can be further divided into two types, plasma methods and ion beam methods, depending on the area to be worked on.

In the sputtering method using the plasma method, glow discharge is generated in an inert gas atmosphere such as Ar, and a target (vapor deposition material) is sputtered with A' ions, and is deposited on, for example, an adherend.

Either a DC sputter link that applies a DC voltage of several KV to the target or a high frequency sputtering that applies a high frequency power of several hundred to several KW may be used.

In addition, in addition to increasing the number of poles from two poles to three poles and four pole sputtering equipment, we also applied a perpendicular electromagnetic field to create a cycloidal motion of the electric r- in the plasma similar to a magnetron (j, e), creating a high-density plasma, and increasing the applied voltage. Magnetron-based sputtering may be used in which the sputtering efficiency is lowered and sputtering is made more efficient.

In the ion beam method, Ar or the like is ionized using an appropriate ion source, extracted, and extracted as an ion beam to the high vacuum side using a negative high voltage applied to an electrode.The ion beam is then irradiated onto the target surface to sputter the sputtered target material. Vapor-deposit onto the target body.

Further, the kinetic energy of the deposited particles in the sputtering method is about several eV to 100 eV, which is extremely large compared to, for example, that in the vapor deposition method (about 0.leV to 1 eV).

In the present invention, the material of the target is the desired metal thinness +15! An alloy or the like corresponding to the composition of the magnetic layer 5 may be used.

By the way, the composition of the metal thin film magnetic layer 5 is set to CoP or Co.
In the case of using N i P, the layer may be formed by a liquid phase plating method, particularly an electroless plating method.

The magnetic layer exhibits good magnetic properties similar to the sputtering method described above.

Various known plating bath compositions, plating conditions, etc. used in electroless plating can be applied, such as those disclosed in Japanese Patent Publication No. 54-9136 and Japanese Patent Publication No. 55-14865.
Any of those described in the No. 1 publication, etc. can be used.

The thickness of the metal thin film magnetic layer 5 as described above is 200~
5000 people, especially 500-1000 people is preferred.

When such a metal thin film magnetic layer 5 is formed by the sputtering method as described above, it is preferable to provide a nonmagnetic metal intermediate layer 4 between the underlayer 3 and the magnetic layer 5. By providing this non-magnetic metal intermediate layer 4, the magnetic properties of the medium are improved and the reliability of the recording properties can also be improved.

It is most preferable that this non-magnetic metal intermediate layer 4 is usually formed from Cr, but the Cr content is 99wL% or more.
That's fine.

This intermediate layer 4 can be formed by various known vapor phase deposition methods, but it is usually preferable to deposit it by sputtering as in the case of the metal thin film magnetic layer 5 described above. The thickness of such a non-magnetic metal intermediate layer 4 should be appropriately determined depending on the type of metal thin film magnetic layer 5 used, but is usually 500 to 40 mm.
Approximately 000 people.

In the magnetic disk 1 of the present invention, it is preferable that a non-magnetic metal protective film 6 such as Cr is provided on the metal thin film magnetic layer 5 described above.

The method for forming this protective film 6 may be the same as that for the nonmagnetic metal intermediate layer described above.

The film thickness of such non-magnetic metal protection Ni 6 is 30-30
0 people, especially 50 to 200 people is preferred.

A protective film 7 is usually further provided on the non-magnetic metal protective flu 6.

Preferably, the protective film 7 is made of carbon.
In that case, the composition is Cr￥1. Although it is made of aluminum, it may contain less than 5wL% of other elements.

The protective film 7 can be formed by various vapor phase deposition methods such as sputtering, ion blating, vapor deposition, and CVD.
Among these, sputtering is particularly preferred. In this case, the formed film becomes extremely dense and has excellent durability and resistance.

The thickness of the protective film 7 thus formed is 10 to 800, particularly 150 to 400. Furthermore, it is preferable that the surface of the protective film 7 is subjected to plasma treatment. Does this change the surface of the protective film? The top coat layer 8, which will be described later and is provided as a more preferable embodiment, can be applied with good adhesion. Therefore, the adhesive strength is in the direction of -4-
Ru.

Plasma treatment may be performed by a known method, such as Ar,
Using one or more processing gases such as Ne, He, N2, H2, etc., the frequency of the power supply is 50 to 13, 56.
Mll7. The degree, applied current, processing time, etc. may be set to normal conditions.

It is preferable to provide a top coat layer 8 on the protective film 7.

The compound to be included in the top coat layer 8 is particularly preferably an organic fluorine compound.

The top coat layer 8 may be formed using any method such as a liquid phase film formation method such as a coating method, a vapor deposition method, a sputtering method, an ion blasting method, a gas phase acid IIQ method such as a plasma polymerization method, etc. Good too.

The thickness of the top coat layer 8 formed in this way is 3 to 3
00 people, preferably 5 to 150 people.

This is because if it is less than 3λ, sufficient effects of the present invention cannot be obtained and the durability is especially poor, and if it exceeds 300 people, adhesion will occur and so-called head crash will occur.

- The magnetic disk l as described above may be a single-sided recording medium as shown in FIG. It may also be used as a recording medium.

■Specific Effects of the Invention The medium of the present invention has irregular concentric grooves on the surface of the non-magnetic substrate or on the surface of the underlayer formed thereon, and A predetermined magnetic layer and the like are provided thereon.

Therefore, the obtained medium has very little head adsorption, excellent durability, magnetic properties, and magnetic field conversion properties, and has extremely high reliability in practical use.

(2) IL-based Examples of the Invention From now on, specific examples of the present invention will be shown and the present invention will be explained in more detail.

(Example 1) Disc-shaped Afif with a diameter of 13 cm and a thickness of 1.9 mm
A NiP layer with a J'X width of 20 μm was provided on f by electroless plating. Note that the electroless plating method was performed under the process and manufacturing conditions described in F.

(NiP electroless plating) Process Manufacturing Conditions 1゜Alkaline Albretsubu 2o4 (manufactured by Jitsukei Pharmaceutical Co., Ltd.)
250 companies/1.65°C, 5 minutes 2, acidic degreasing Albretsubu 23o (manufactured by Jitsukei Pharmaceutical Co., Ltd.) 150 companies/2.65°C, 5 minutes 3, Zincate Arp 3o2 (manufactured by Jitsikei Pharmaceutical Co., Ltd.) 250
1ffi/Q, 25℃, 30 seconds 4, zincate 6
2 VO1% concentrated nitric acid, peeling fJi 800rd/
l, 25°C, 30 seconds 5, Zincate Arp 3o2 (manufactured by Jitsukei Pharmaceutical Co., Ltd.) 250 rml/l, 25°C, 20 seconds 6, Surface! 1 hour Sodium bicarbonate 30g/! l, 2
0°C, 30 seconds 7, Nickel metal Niclad 719A (manufactured by Jitskei Pharmaceutical Tsuki Co., Ltd.) 80nJI/l Niclad 71
9B (manufactured by Jitsukei Pharmaceutical Co., Ltd.) +50iffi/fl pH 4.5, 90°C, 2 hours The composition of the base layer is Ni:P = 85 2 15 double 5 ratio)
And so.

Next, the geological formation described in L was polished under the conditions described in L.

<Surface polishing treatment> Using a lapping machine 9B-5P manufactured by Speed Fam ■, polishing liquid of Fujimi Polishing Co., Ltd. and Mediball No. is applied while rotating the substrate described in .

8 (50% diluted solution), polishing was performed for 10 minutes while applying a load of 100 g.

Thereafter, it was cleaned using a disk substrate cleaning device (manufactured by Speed Fam Clean System ■). The process is as shown below.

<Cleaning process> 1. Neutral detergent solution, immersion, ultrasonic 2, M pure water, scrub 3, ultrapure water, scrub 4, ultrapure water, immersion, ultrasonic 5, ultrapure water, immersion 6, Freon/ Ethanol mixture, immersion, ultrasonic waves 7, CFC/ethanol mixture, immersion 8, CFC/ethanol, steam (→dry) After these cleaning steps, concentric irregular grooves are created on the surface of the base layer as shown below. (hereinafter referred to as texturing process). That is, using a tape polishing machine (manufactured by Tomoe Techno Corporation), concentric irregular grooves were formed on the surface of the substrate while rotating the substrate. The process conditions were: polishing chip number J$4000, contact pressure 1.2 g/crn'', oscillation 3250 times/min, work rotation '#!L 150 times/min, and oscillation amplitude 3 mm.

This is referred to as processing 1 of the present invention.

In this case, the average value of the depth of the grooves was 0.03 μm, and the average value of the number of grooves was 800 wood/mra.

As a comparison process 1, in the process of the present invention, the base body was reciprocated in one direction at an amplitude of 250 mm and a speed of 500 mm/sec, and oscilloscope control was performed in a direction perpendicular to this at an amplitude of 3 degrees and a linear speed of 10 mm/sec. Grooves were formed in one direction on the surface of the base layer with approximately the same depth and distribution as in item 111.

Thereafter, after further cleaning in the same manner as in the serious case, a non-magnetic magnetic metal intermediate layer made of Cr was deposited to a thickness of 2000 mm by sputtering. The layer installation conditions were Ar pressure 2. OPa, DC8
It was set as KW.

Note that an Ar gas pressure of 0. 2Pa, R
Etching treatment was performed under the condition of F400W.

Thereafter, each sleeve metal thin film magnetic layer as shown below was formed continuously on this -L.

<Formation of metal thin film magnetic layer> A CoNi@i layer was formed using a sputtering method. The film forming conditions were Ar gas pressure 2. OPa, DC8KW.
The CoN i composition weight ratio is Co/N i = 80/
20.11!2 thickness was set at 600 people.

A nonmagnetic metal protective film made of Cr was formed on the metal thin diamagnetic layer thus formed.

Film formation is performed by sputtering, and the conditions are Ar gas pressure 2.
OPa, DC8KW, and film thickness were set to 200.

Further, on this protective film, a carbon protective film with a thickness of 400 mm was provided by sputtering. Note that the sputtering conditions are A
The r gas pressure was 0.2 Pa and the DC was 8 KW.

The surface of this carbon protective film was subjected to plasma treatment. Note that the plasma conditions are processing gas N2. Pressure 5Pa, power supply 1
3. The high frequency is 56MIIz, and the input gravity is 3KW.
And so. It contains a lubricant as shown in C.
A whirlpool coat layer was applied using a spin cord method. The spin code conditions were a rotation speed of 1000 rpm and a duration of 10 seconds.

The film thickness was 100 people.

<Top coat layer composition 1> KRYT consisting of the structural formula shown below as Po1 sliding
OXI 57FS (manufactured by DuPont) (where n=11
~49) to Freon 113 (manufactured by Daikin Industries, Ltd., Daiflon 5-3)
) in a solvent, and the concentration of the lubricant-containing coating solution was 0.05.
Adjusted to vehicle volume%.

(1) The number of errors per disk recording surface is determined to be 1lill immediately after creating a 1 animal, 2 milk, 5" L magnetic disk sample and after 30,000 CSS (contact start and stop) operations, and the errors before and after C5S are determined. The increase in the number of missing pulses (number of missing pulses) is displayed [2 pits/plane].

The number of errors per disk recording surface was measured using a magnetic disk defyer manufactured by Nippon Qden R-Engineering Co., Ltd., and the setting conditions were a missing pulse slice level of 65%. A Mn-Zn monolithic head was used as the head.

(2) Adsorption CSS (contact start and stop)
After 30,000 tests, the Mn-Zn ferrite head was left stationary on the surface of the magnetic disk sample under conditions of 20°C, 60% RH, and 172 hours, and the initial friction coefficient when the sample was suddenly rotated was determined. It was measured.

From the results in Table 1, the effects of the present invention are clear.

Note that for sample No. 103, the surface treatment of the base layer was not performed.

Sample No. 101 (present invention) and sample N described in
o, 103 (comparison) both - output waveform is uniform,
There was no increase in errors.

From these results, it can be seen that the product of the present invention improves the durability, abrasion resistance, adsorption characteristics, etc. of the medium without deteriorating the electromagnetic conversion characteristics.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of a magnetic disk of the present invention. Brief explanation of symbols 1...Magnetic disk, 2...Nonmagnetic substrate, 3...
4... Nonmagnetic metal intermediate layer, 5... Metal thin film magnetic layer, 6... Nonmagnetic metal protective film, 7... Protective film,
8...Top coat layer, 9...Groove

Claims (1)

[Claims] (1) In a magnetic disk having a metal thin film magnetic layer on a disk-shaped and rigid non-magnetic substrate, a circle approximately concentric with the surface of the magnetic layer forming side of the substrate or the surface of the underlayer formed thereon. A magnetic disk characterized by having grooves in the shape of a shape.