JPH0258730A - Magnetic disk substrate - Google Patents

Abstract

PURPOSE:To prevent the attraction of a magnetic head and to obtain a magnetic disk having excellent durability by forming a magnetic disk substrate of a base body and many fine particles stuck on the surface of the base body. CONSTITUTION:The magnetic disk substrate 1 is made into the structure consisting of the base body and the many fine particles 2 stuck on the base body surface, by which the many microprojections are formed on the surface. The height of the microprojections are preferably smaller than the floating amt. of the head in order to avert the collision of the disk and the head and is larger than the film thickness of a lubricating agent in order to avert the tight contact of the head and the disk. The fine particles to be used are preferably the fine noble metal particles and the treatment to stick the fine noble metal particles onto the base body is preferably executed by a method of immersing the base body into a treating liquid dissolved mainly with the noble metal salt of palladium, gold, silver, etc., to stick the noble metal particles to the base body. The attraction of the disk to the magnetic head is prevented and the magnetic disk having the excellent durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk substrate for a magnetic disk used in a magnetic disk device, which is one type of magnetic recording device.

(Prior Art) In recent years, the importance of magnetic disk devices in file storage devices has increased, and the recording density thereof has been significantly improved year by year. Hitherto, so-called coated disks, in which a mixture of iron oxide magnetic powder and an organic resin binder is coated on a substrate and then polished, have been widely used as magnetic recording media.

In coated type disks, in addition to being able to contain a lubricant in the kneaded layer of magnetic powder and organic resin binder, the magnetic layer is thick at 0.511 m or more and the surface roughness Rmax is 0.0511 m, which is about 10% of this. Since the front and back (Ra is about 0.0111m, which is a few minutes of Rmax) are relatively large, it is possible to provide a sufficiently thick lubricating film without the head adsorption, and prevent contact and sliding with the magnetic head. Excellent durability. However, in order to achieve even higher recording densities in the future, it will be necessary to make the magnetic recording layer thinner, which is a disadvantage for coated disks. Therefore, thin-film magnetic disks whose magnetic recording layer is a magnetic thin film formed by plating, sputtering, vapor deposition, or the like have begun to be used as high-density magnetic recording bodies.

Conventionally, as a substrate for a thin film magnetic disk, a substrate such as an aluminum alloy substrate on which a Ni alloy plating film is formed and polished is used. Usually, this substrate is made by plating a Ni alloy plating film with a thickness of several pm to several tens of pm on an aluminum alloy substrate, and then mirror-polishing it to a surface roughness of about RaO,004 pm or less by polishing methods such as lapping and polishing. (Telecommunication Research Institute Research and Practical Application Report 26-2, p. 471, 1977).

However, when a magnetic thin film is formed on this substrate, the thickness of the magnetic thin film, which is several times smaller than that of the magnetic recording layer of a typical coated disk, is smooth and uniform, and there is no place for lubricant to accumulate on the magnetic disk surface. Therefore, only a very small amount of lubricant can be held, resulting in a problem that the C55 (contact start/stop) durability of the magnetic head is poor. In addition, when a liquid lubricant is applied to the surface of a mirror-polished magnetic disk, adhesion occurs between the smooth surface of the magnetic disk and the slider surface, which tends to cause damage when starting the disk. A method in which a mirror-polished Ni alloy plated substrate is rotated and brought into contact with a tape containing abrasive grains to form concentric thin stripes (texture), such as
A method has been proposed in which a Ni alloy plated substrate is mirror-polished with fine abrasive grains and then polished with coarse abrasive grains to increase the surface roughness.

(Problem to be Solved by the Invention) However, in this method of forming a rough surface by machining, relatively large abrasive grains in the polishing abrasive grains and foreign matter mixed in during polishing can cause signal errors. Polishing streaks are likely to occur, and it is difficult to obtain a uniformly moderately rough surface over the entire surface of the disk. These non-uniform polishing streaks affect the characteristics of the magnetic layer, resulting in the reproduction output envelope, S/N
However, there has been a problem in that recording/reproducing characteristics such as bit errors and servo signal quality deteriorate. Furthermore, in machining, the surface roughness obtained is almost determined by the size of the abrasive grains used, making it impossible to finely control the surface roughness and making it difficult to increase the density of the polishing streaks. Ta. Therefore, in order to prevent head adsorption and provide a lubricating film of sufficient thickness, it is necessary to considerably increase the surface roughness, which poses a problem of deterioration of electromagnetic conversion characteristics. In addition, such precision machining is difficult to mass-produce at once, and there are also problems with productivity.

An object of the present invention is to obtain a magnetic disk that does not increase bit errors, reduce re-output envelope, recording/reproducing characteristics such as S/N, and servo signal quality, and has excellent durability by preventing adhesion with a magnetic head. An object of the present invention is to provide a magnetic disk substrate and a method for manufacturing the same.

(Means for Solving the Problems) The magnetic disk substrate according to the present invention is characterized by comprising a base and a large number of fine particles adhered to the surface of the base.

The object of the present invention can be achieved through the basic structure of the magnetic disk substrate according to the present invention. The configuration of the present invention will be described in more detail.

Requirements such as surface roughness (in particular, height, size, shape, density, etc. of microprotrusions on the surface) of a disk using the magnetic disk substrate according to the present invention vary depending on the conditions under which the magnetic disk is used. . In order to prevent adhesion to the magnetic head and obtain a magnetic disk with excellent durability, depending on the head/disk conditions such as the type, structure and material of the head, flying height of the head, type of lubricant and protective film, and film thickness. Although conditions such as the height and shape of the microprotrusions are selected depending on each case, the inventor's study revealed the following. The height of the microprotrusions is desirably smaller than the flying height of the head to avoid collision between the disk and the head, and greater than the film thickness of the lubricant to avoid close contact between the head and the disk. Head flying height is usually 0.6p
The lubricant film thickness, which is set to 0.311 m or less for recent disk devices and 0.2 pm or less for high-density disk devices, ranges from a few monomolecular layers for thin cases to several layers for thick cases. Tens to hundreds of holes are used depending on the situation. In order to prevent adsorption with the magnetic head and improve durability, the height of the microprotrusions should be several angstroms or more and 0.6 pm or less,
Preferably, the thickness is more than ten angstroms and less than 0.2 pm. Considering the conditions of current high-density disk devices (linear density of 20,000 BPI (bits per inch) or more), the
．． It was found that 1 pm or less is preferable. The size of the microprotrusions varies depending on the tolerance of the recording/reproduction characteristics that they affect, but smaller protrusions are preferable in order to maintain good characteristics. Currently, substrate surfaces are roughened by mechanical polishing, but the abrasive grains used for this are often in the range of several pm to 0.8 pm in diameter, and this shape is not reflected in the processed surface. Ru. For this reason, when the surface is roughened by polishing, the recording and reproducing characteristics often deteriorate. However, it has been found that when forming microprotrusions, the recording and reproducing characteristics are hardly affected by setting the size to 0.7 pm or less, preferably 0.4 pm or less. In order to prevent adhesion with the magnetic head and improve durability, it is better for the height of the microprotrusions to be large.
Even if the height of the microprotrusions is relatively small, a significant effect can be observed if the density of the microprotrusions is large. The higher the density of microprotrusions, the better the durability was obtained. in particular,
1011m2 if the height of microprotrusions is O,11pm or more
1 or more pieces per 2 pm, preferably 1 or more pieces per 5 pm2,
When the height of the microprotrusions is 0.1 pm or less, the density of one or more microprotrusions per 5 pm2, preferably one or more per 311 m2, has a remarkable effect on preventing adhesion to the magnetic head and improving durability. The height, size, shape, density, etc. required for microprotrusions on the surface of the magnetic disk substrate, that is, the surface roughness, may vary depending on the magnetic layer, protective layer, etc. formed on the magnetic disk substrate. , and will be increased or decreased accordingly in accordance with the above principles.

The substrate used in the magnetic disk substrate of the present invention includes a substrate, or a substrate coated with various additional films, such as a substrate coated with a thick base film,
Furthermore, there are those that are coated with a base thin film.

Metal substrates such as aluminum alloy, copper, brass, phosphor bronze, iron, and titanium are usually used as substrates, but these can also be made of glass, ceramics, or resin by oxidizing, chromating, or appropriately activating the surface. As a base thick film or base thin film that can be applied to non-metallic substrates such as NiP or Ni
Although it is preferable to use the electroless plated film of B, it is also possible to use an electroplated film, a dry plated film by sputtering, vapor deposition, or the like. Furthermore, NiP or NiB
The film contains Mn, Fe, Co, and AI.

Ta, Li, Mg, Ti, V, Cr, Cu
, Zn, Ge, Y, Zr, Nb, Mo,
Ru.

Rh, Pd, Ag, Au, Sn, Sb, T
e, Cs, W, Re, Pb, Bi, La,
Ce.

It may contain at least one element such as Pr, Nd, Ac, Ba, Pt, or Sm, and further contains P, B, C, or N.

0, S, As, Na, K, F, C1, Br
, I, Ca, and other non-metals may be included. Further, the base thick film and base thin film are not limited to Ni alloy films, and may include W, Mo, etc.

Cu, Sn, Zn, Re, Mn, Fe, C
r, Co, Au, Ag, AI, Ta, Ti
, V.

The film may be made of at least one element such as Si, and further include P, B, C, N, O, S,
As, Na,, F.

Nonmetals such as CI, Br, I, and Ca may also be included.

Further, the thick base film and the thin base film do not need to each be a single layer, but may be multilayers with metal or various alloy films. The base thick film is usually 1 to 50p in order to obtain a smooth surface precision.
m, preferably 10 to 30) After forming a film with a thickness of about 1 m, it is polished. The base thin film is usually less than the thick base film, and is formed for the purpose of controlling the characteristics of the magnetic film thereon, eliminating the influence of the substrate on the magnetic film, and the like.

The fine particles used in the magnetic disk substrate of the present invention are preferably noble metal fine particles, and are deposited in large numbers on the substrate surface, for example, by the following method. Preferable methods for adhering precious metal particles include a method in which the substrate is immersed in a treatment solution containing mainly dissolved noble metal salts such as palladium, gold, and silver, and the noble metal particles are adsorbed; however, wet or dry plating methods, such as electroless plating, Noble metals such as palladium, gold, silver, platinum, rhodium, ruthenium, copper, etc. may be deposited by electroplating, sputtering, vapor deposition, ion blating, cluster ion beam deposition, or other processing methods. Most magnetic disks have a multilayer structure, from the substrate to the protective film and lubricating film, containing metals (base metals) that have a greater ionization tendency than these noble metals. Therefore, the roughened state of the precious metal due to the minute protrusions is stable, and there is little possibility that it will be eluted or altered by subsequent film formation. Furthermore, these noble metals are non-magnetic and have little effect on the recording and reproducing characteristics of the magnetic recording medium. For this reason, noble metals were selected, but metals, alloys, and compounds with lower ionization tendency and lower magnetism than the layers constituting the magnetic disk may also be used.

As the noble metal fine particle adhesion treatment using a treatment liquid, an activation treatment method that is a pretreatment for plastic plating or the like can be used. This involves a two-step activation treatment method consisting of sensitization treatment using a tin chloride solution in an acidic region and activation treatment using a palladium chloride solution, and promotion using a tin-palladium colloidal catalyst solution and an acid/alkaline solution in an acidic region. One-step activation treatment method consisting of chemical treatment, one-step activation treatment method using tin-palladium complex catalyst solution performed in alkaline region, activation treatment method using noble metal salt solution that can be performed in acidic, alkaline, or neutral conditions, etc. There is.

The two-step treatment method that has been widely used in the past is described in U.S. Pat.
As shown in No. 702253, this process includes sensitization treatment with a sensitizer solution consisting of a 5nC1□ solution, followed by activation treatment with an activator solution containing noble metal ions such as Pd, Au, and Ag. As a result, P, which has a catalytic effect on the plating reaction, is deposited on the substrate surface.
Fine particles such as d, Au, and Ag adhere to the surface. As an example of the treatment liquid composition, see Metal Surface Technology Course 9 "Electroless Plating"
Narcus liquid (acidic): SSnC12Lo/l, as seen in , Chika Ishibashi, Breakfast Shoten, published in 1968.
HCI 40ml/l.

Narcus solution (alkaline): 5nC1□100
g/l 1 Rochelle salt 175g/l, NaOH15
0g/IWeiss liquid: 5nS0425~40g/11
H2S045~20m1/1, alcohol 150~25
0ml/l, quinol 5-15ml/l, water 600-1
0100O/I Walker liquid: Sn01290g/l, HCI 5
Sensitizer liquid such as 5m1/1, Pd treatment liquid (1): PdC1□2g/l, HCI
20ml/l, Pd treatment liquid (2): PdC1□0.
15-0.25g/l, HCI 2.5ml/1, Au
Treatment liquid: chloroauric acid 1g/l, HCI 2ml/1, Ag
Treatment liquid: silver nitrate 1.5g/l, ammonia 1.2ml/
An activator liquid such as No. 1 can be used.

Further, as examples of commercially available liquids, Pink Schumer (sensitizer liquid), Red Schumer (activator liquid), etc. manufactured by Nippon Kanigen Co., Ltd. can be used.

In recent years, US Patent No. 301192 has been developed as a more uniform catalytic method.
As shown in No. 0, No. 3,532,518, and No. 3,650,913, a one-step treatment method consisting of a catalytic treatment using a tin-l-palladium colloidal catalyst solution and an acceleration treatment solution using an acid or alkaline solution has been carried out. As an example of the treatment liquid composition, T. Osaka et al.
a et al), Journal of Electrochemistry, Society (J, Electrochemi
cal 5ociety).

As stated in Volume 127, No. 5, 1980, page 1021, AjTt: HCl 60m1/1 → Water → PdC1□
Colloidal solution prepared in the order of 1g→5nC122H2022ρ and made to 10100O by adding water, Solution B: HCI 6
0m1/1-+water→PdCl20.25→5nC122
H2012ff) and add water to 10100O
Colloidal liquid, Solution C: HCl 300ml + Water - + PdC1□Ig
-+Na25nO31,5g-+5nC122H203
Colloidal solution prepared by adding in the order of 7 and 5, n night: 320 ml of HCl + water → 1 g of PdCl + 5 n
Added around C1□22H2O4!7)) and 5nC after aging for 1 day.
Commercially available solutions such as colloidal solution prepared by adding 2046g of 122H are Solution E: Hydrochloric acid-based colloidal solution H8 manufactured by Hitachi Chemical Co., Ltd.
Catalyst solutions such as 10IB, E' liquid, hydrochloric acid-based colloidal liquid Catalyst 9F manufactured by Niji Playfast, and F liquid, salt-based colloidal liquid Cataposit 44 manufactured by Niji Playfiest, and T. Osaka et al. ,
Journal of the Electrochemical Society (J.

Electrochemical 5ociety),
As stated in Vol. 127, No. 11, 1980, p. 2343, G solution: NaOH 1 mol/l, H solution: HCI 6
mol/1, ■Liquid: H2So41.12mol/I,
J solution: ammonia 1 mol/l, K solution: NH4B
Commercially available liquids such as F41 mol/1, L liquid: Hitachi Chemical A
Accelerating treatment liquids such as DP201 and M liquid Niji Play First's Accelerator 19 can be used.

More recently, soot/palladium complex catalyst solutions that operate in the alkaline region have come into use. A commercially available solution is Activator Neogant 834 manufactured by Schering.

As a surface roughening treatment method using a noble metal salt solution carried out in an acidic, alkaline or neutral region, the activator liquid Pd treatment liquid (1), Pd treatment liquid (2), Au treatment liquid,
Ag treatment liquid or the like can be used.

The PdC1□ concentration is in the range of 0.0001 to 50 g/l, preferably 0.005 to 15 g/l, and the chloroauric acid concentration is in the range of 0.001 to 30 g/l, preferably 0.1
~IOg/I range is 0.001 as silver nitrate concentration
A range of from 0.1 to 15 g/l is used, preferably from 0.1 to 15 g/l. HCI concentration is 0.001 to 500
m1/1, preferably in the range of 0.1 to 100 m1/l, and the ammonia concentration is 0.005 to 600 m1/l.
l, preferably in the range from 0.1 to 150 m1/l. As noble metals, in addition to Au, Ag, and Pd, elements such as Pt, Rh, Ru, and Re can be used, and as noble metal salts, in addition to chlorides, sulfates, nitrates, organic acid salts, etc. can be used. be able to. In addition to hydrochloric acid, sulfuric acid, nitric acid, organic acids, etc. can also be used. In addition, additives such as pH buffering agents, organic acids such as succinic acid and acetic acid that act as complexing agents, and surfactants may be added. Commercially available liquids include Activated Liquid 1 manufactured by Nippon Kanigen Co., Ltd. for acidic liquids and Activated Liquid 2.3 manufactured by Nippon Kanigen Co., Ltd. for alkaline liquids. As a treatment method, the treatment temperature is 0 to 95°C, preferably 15 to 95°C.
The immersion treatment is carried out at a temperature of 800C and an immersion treatment time of 1 second to 100 minutes, preferably 5 seconds to 15 minutes. The pH of the treatment solution is
In the case of HCI acidity, the pH is usually 1 or less, but it may be carried out in alkaline pH of 14 or more, or in the pH range therebetween, and is not particularly limited.

By selecting various processing conditions as described above, the height, size, density, etc. of the noble metal fine particles can be changed. Generally, the longer the immersion treatment time and the higher the concentration of the treatment solution (particularly the concentration of noble metal salt), the greater the height and size of the noble metal fine particles.

The above processing method does not necessarily result in the attachment of noble metal fine particles and the formation of microprotrusions, which is the object of the present invention. The relationship with the state of the surface to which this treatment is performed is important, and it is desirable to perform surface modification as a pretreatment. Acid treatment, alkali treatment, etc. are used for surface modification treatment. If the subsequent surface roughening treatment is acidic, acid treatment is used; if alkaline, alkali treatment is used. Adjustment treatment conditions such as immersion time are selected depending on the required form of noble metal fine particles, surface roughness, and noble metal fine particle adhesion treatment to be used.

The state and composition of the surface of the obtained magnetic disk can be investigated using a transmission electron microscope, a secondary electron beam microscope, a surface roughness meter, an analytical electron microscope, a scanning Auger electron analyzer, an X-ray microanalyzer, etc. can. By such a wet or dry treatment method, noble metal fine particles containing at least one noble metal such as palladium, gold, silver, platinum, rhodium, ruthenium, copper, etc. as a main component can be formed.

The noble metal fine particles may contain at least one of C1 and C10 within a range that does not impair the effects of the present invention. The noble metal fine particles further contain Mn and Fe within a range that does not impair the effects of the present invention.

Co, AI, Ta, Li, Mg, Ti, V
, Cr, Zn, Ge, Y, Zr, Nb,
Mo.

Sn, Sb, Te, Cs, W, Pb, Bi
, La, Ce, Pr, Nd, Ac, Ba,
Pt.

At least one element such as 8m may be contained, and further P, B, N, S, As, N
a, K, F, Br, I.

Non-metals such as Ca may also be included. These noble metal fine particles adhere to the surface of the substrate and form microprotrusions, and it was possible to form microprotrusions on the surface according to the required conditions such as height, size, shape, density, etc.

A magnetic layer, a protective layer, a lubricant layer, and the like are sequentially formed on the magnetic disk substrate of the present invention to produce a magnetic disk.

The magnetic layer formed on the magnetic disk substrate is a magnetic film containing at least Co, Ni, and Fe, but may also be an alloy film containing additional elements such as P and B. An oxide film or a nitride film containing N may be used. Other additive elements for the magnetic film used are not particularly limited, but include Re, Mn
, W, Li, Be, Mg, AI.

Ru, Si, Mo, Zn, Sr, Y, Zr
, Nb, Cd, In, Sb, Ta, Ir,
Hg.

Tl, Ti, V, Cr, Cu, Ga, Ge
, Tc, Rb, Ra, Hf, Rh, Pd,
Ag.

Au, Pt, Sn, Te, Ba, Cs, O
Elements such as s, Sc, Se, Pb, Bi, and lanthanum series rare earth elements may be included. In addition to these elements, the magnetic film also contains C, S, and As.

Nonmetals such as Na, K, F, CI, Br, I, and Ca may be included. In the magnetic film, C01
Ni and Fe are contained in an amount of 10% or more, preferably 50% or more. P and B are contained in a maximum amount of about 30%, but preferably in a range of 15% or less. The magnetic film thickness is preferably in the range of 0.003 to 311 m, but is preferably 0.5 pm or less for high-density recording. The magnetic layer is 1
Used in a layer or two or more layers. In the case of two or more layers, magnetic films having the same or different compositions and magnetic properties are laminated directly or via a nonmagnetic film. These films are formed by wet plating methods such as electroless plating and electroplating, or dry plating methods such as sputtering, vapor deposition, and ion blating. Usually these are called thin film media,
Used for plating disks, metal sputter disks, ferrite sputter disks, vapor deposition disks, etc. The protective layer used is a thin protective film, or one in which various additional films are formed under and/or on the thin protective film, for example, a thin protective film coated on a top thin film;
Furthermore, there are those that have a lubricating film coated thereon, those that have an additional film coated on the top thin film and are further coated with a thin protective film, and those that have a lubricating film further coated thereon. Each of these films may have one layer or multiple layers. The thin protective film can be made of amorphous metalloid oxides generally called glassy substances such as quartz glass, silicate glass, phosphate glass, and amorphous alumina, and amorphous materials such as polysilicic acid, which is a condensation compound of tetrahydroxysilane. Although it is preferable to use a pure inorganic oxide film or a carbon film, a silicon compound film such as Si3N4, a metal film such as Rh or Ag, or an oxide film such as Co oxide or CoNi oxide may also be used. These films can be formed by sputtering, vapor deposition, plasma CVD, plasma injection CVD, dry plating such as ion blating, electroless plating, wet plating such as electroplating, coating, or oxidation in solution. It is formed by a method such as a processing method or a thermal oxidation method.

As the upper thin film, it is preferable to use a thin film of Ni alloy, chromium compound, zirconium compound, etc., but the same materials as the above-mentioned thick base film and thin base film can also be used. As the lubricating film, non-polar solid lubricants, polar solid lubricants, liquid lubricants, etc. are used (46th Japan Society of Applied Magnetics Research Materials, 46-5, 1986). Furthermore, various variations are possible in the configuration of the magnetic disk. - Examples include those in which a pretreatment layer of chromium, molybdenum, titanium, silicon, gold, etc. is formed under the magnetic layer for the purpose of controlling the magnetic properties and crystal structure of the magnetic recording layer, and making it easier to manufacture. Multi-layered magnetic recording layer directly or via a non-magnetic layer for the purpose of improving recording characteristics or multiplexing data information and servo information, etc., and a multi-layered structure with multiple protective films to further improve weather resistance. Examples include those made by

(Function) In a magnetic disk that uses a magnetic thin film as a medium for high-density magnetic recording, the surface is smooth and there is no place for lubricant to accumulate, so the C8S durability with the magnetic head is poor, and if the amount of lubricant is increased, the magnetic There was a problem that adsorption occurred between the Herad slider and the surface. For this reason, it is widely practiced to create lines called texture by machining on the smooth disk substrate surface. However, this method of forming a rough surface by machining tends to cause signal errors due to non-uniform polishing roughness, and it is difficult to increase the density of polishing streaks because the roughness cannot be precisely controlled. In order to prevent head adsorption and provide a sufficiently thick lubricating film, it is necessary to considerably increase the surface roughness, which poses a problem of deterioration of electromagnetic conversion characteristics.

The inventors conducted a detailed study on the effects of the roughness and shape of the disk surface on head adsorption, durability, electromagnetic characteristics, etc., and found that fine particles could be attached by physical or chemical surface treatment rather than machining. This method provides a much finer and denser surface shape and is easier to control. It has become clear that the protrusions (protrusions) are much more effective in preventing head adsorption. It has also been revealed that microprotrusions produced by physical or chemical surface treatment can be formed finely and densely, so a small surface roughness is sufficient, and good results can be obtained in terms of durability, electromagnetic conversion characteristics, etc. Conditions such as the height and shape of the microprotrusions are selected depending on the head and disk conditions in order to prevent adsorption with the magnetic head and obtain a magnetic recording medium with excellent durability. The effect of the amount of microprojections (density of microprojections) was more significant.

Furthermore, although it is extremely important to control the microprotrusions into the desired shape, it has become clear that the surface roughness can be easily controlled by changing the processing conditions for adhering the microparticles. The present invention was brought about by obtaining such knowledge.

[Example] (Example 1) After performing known pretreatment (cleaning, zinc substitution treatment, etc.) on an aluminum alloy substrate (inner diameter 100 mm outer diameter 210 mm),
Uezai Kogyo Co., Ltd. Muden HDX in electrolytic NLP plating solution
) was used to plate a nonmagnetic N1-P base thick film with a film thickness of 20 pm. Next, the surface of the underlying thick film was mirror-polished to obtain good surface precision (RaO, 0012pm, TIR≦19pm,
Acceleration≦1.9G) was obtained. Next, an adjustment process was carried out, and noble metal fine particles were attached on the surface under the following conditions to form a magnetic disk substrate having the structure shown in FIG.

Precious metal fine particle adhesion treatment (1) Sensitizer liquid (Sn0125g/l, HCl25r
After soaking for 0.5 minutes in activator solution (PdC120,05g/l, HCl 0.5m
l/1.35°C) for 1 minute.

Precious metal fine particle adhesion treatment (2) Sensitizer liquid (SnC1255g/l 1 Rochelle salt 100g/l, NaOH90g/l, 30°C)
After 1 minute immersion in activator solution (chloroauric acid 0.5g/
1 ml of HCI/1130°C) for 1.5 minutes.

Precious metal fine particle adhesion treatment (3) Sensitizer liquid (SnC1s+ 7g/l, HCI
After 1 minute immersion in 35 m/l/l, 40°C), activator solution (silver nitrate 0.5 g/l, ammonia 1 ml/1
．． 50°C) for 1.5 minutes.

Precious metal fine particle adhesion treatment (4) After immersing in sensitizer liquid (Pink Schumer, manufactured by Nippon Kanigen Co., Ltd., 10 times diluted, 30°C) for 0.5 minutes, activator liquid stamp was applied. Soak in C) for 0.5 minutes.

Precious metal fine particle adhesion treatment (5) Catalytic treatment liquid (Liquid A: HCI 60ml/l-+water→
Colloidal liquid prepared in the order of PdPdC12l + 5nC1□22H2O22 and adjusted to 10100O by adding water, 25
°C) for 70 seconds, then add the acceleration treatment solution (K solution: NH
4BF41mol/l, 40°C) for 1 minute.

Precious metal fine particle adhesion treatment (6) Catalytic treatment liquid (D liquid: HCI 320ml → Water → Pd
After adding 1 g of C1□→5nC1□22H2O4 and aging for 1 day, the colloidal solution prepared by adding SSnCl22H2O46 (25°C) was immersed for 0.5 minutes, and then the acceleration treatment solution (
K solution: Immersed in NH4BF41mol/1.50°C for 3 minutes.

Precious metal fine particle adhesion treatment (7) Catalytic treatment liquid (E' liquid Hydrochloric acid-based colloidal liquid Catalyst 9F made by Niji Play Feast 1 volume, 2 volumes of hydrochloric acid, 4 volumes of water)
After immersing it in a solution with a volume of 20°C for 90 seconds, the accelerator 19.
25°C) for 1 minute.

Precious metal fine particle adhesion treatment (8) Catalytic treatment liquid (F solution: 270 g of Catalyst 404 dissolved in 840 ml of water, mixed with 15 ml of salt-based colloidal liquid Catabosite 44 made by Sibley Fist)
After dipping for 90 seconds in a solution added at an addition rate of 100 ml (45°C), it was immersed for 1 minute in an accelerator solution (M solution, Niji Play Fist accelerator, 19.30°C).

Precious metal fine particle adhesion treatment (9) Activator liquid (PdC120.01g/l, HCI
10m1/1.80°C) for 1 minute.

Precious metal fine particle adhesion treatment (10) Activator liquid (chloroauric acid 0.3 g/l, HCI
4ml/l.

40'C) for 1.5 minutes.

Precious metal fine particle adhesion treatment (11) Activator liquid (silver nitrate 0.4g/l, ammonia 0
．． 9ml/l, 40°C) for 1 minute.

Precious metal fine particle adhesion treatment (12) Activator liquid (acidic activation liquid 1.1 manufactured by Nippon Kanigen Co., Ltd.)
0x dilution, 35°C) for 30 seconds.

Precious metal fine particle adhesion treatment (13) Immersed in activator solution (Nippon Kanigen Co., Ltd. alkaline activator solution 3.4 times diluted, 35°C) for 1 minute.

The magnetic disk substrates obtained in this way are numbered magnetic disk substrate 1 to magnetic disk substrate 13 in correspondence with the noble metal fine particle adhesion treatment number.

Electron microscopic observation of the surface of the obtained magnetic disk substrate (S
As a result of performing EM and TEM), the height was 0.015p.
It was observed that microprotrusions with a diameter of m to 0.025 pm were formed at a density of one or more per 0.711 m2.

The size of the microprotrusions was 0.04 to 0.07 pm, and had the shape of a slightly flattened hemisphere. The microprotrusions were uniform in height, size, and shape, and were uniformly and densely formed on the surface of the magnetic disk substrate.

(Example 2) A magnetic disk substrate was produced in the same manner as in Example 1, but in this example, noble metal fine particle adhesion treatment was performed under the following conditions.
A magnetic disk substrate having the structure shown in FIG. 1 was formed.

Precious metal fine particle adhesion treatment (14) Sensitizer liquid (SnC1□5g/l, HCI
After immersion for 1.5 minutes in 25ml/1.30°C), the activator solution (PdC120,05g/l, HCI 0.
5ml/l, 40°C) for 4 minutes.

Precious metal fine particle adhesion treatment (15) Sensitizer liquid (Sn01□55g/l, Rochelle salt 100g/l, NaOH90g/l, 30°C)
After soaking for a minute, activator solution (chloroauric acid 0.5g/I
, HCI 1ml/1.30°C) for 5 minutes.

Precious metal fine particle adhesion treatment (16) Sensitizer liquid (SnC1□7g/l, HCI 35
m/1/l, 40°C) for 2 minutes, then activator solution (silver nitrate 0.5 g/l, ammonia 1 ml/l, 6
0°C) for 4 minutes.

Precious metal fine particle adhesion treatment (17) After immersing in sensitizer liquid (Pink Schumer, manufactured by Nippon Kanigen Co., Ltd., 10 times diluted, 35°C) for 1.5 minutes, activator liquid stamp was applied. Soak in C) for 5 minutes.

Precious metal fine particle adhesion treatment (18) Catalytic treatment liquid (Liquid A: HCI 60ml/l → Water → P
Colloidal liquid prepared in the order of dCl21g → 5nC1□22H2O22 and made to 10100O by adding water, 30°C
) for 4 minutes, then add the acceleration treatment solution (K solution: NH4BF
41mol/1.40°C) for 1.5 minutes.

Precious metal fine particle adhesion treatment (19) Catalytic treatment liquid (D solution: HCl 320ml−+water−+
PdPdC12l + 5nC122H204g were added in this order and aged for 1 day, then immersed for 4 minutes in a colloidal solution (30°C) prepared by adding SSnCl22H2O46, and then 2.
Soak for 5 minutes.

Precious metal fine particle adhesion treatment (20) Catalytic treatment liquid (E' liquid Hydrochloric acid-based colloidal liquid Catalyst 9F manufactured by Niji Play First 1 volume, 2 volumes of hydrochloric acid, 4 volumes of water)
After soaking for 4.5 minutes in the same solution (35°C), apply the accelerator 1
9. Soak at 30°C for 2 minutes.

Precious metal fine particle adhesion treatment (21) Catalyst treatment liquid (F solution: 270 g of Catalyst 404 dissolved in 840 ml of water, mixed with 15 ml of salt-based colloidal liquid Catabosite 44 made by Sibley Fist)
After immersing for 3.5 minutes in a solution added at an addition ratio of 1.1 at 50°C, it was then immersed for 1 minute in an accelerator solution (M solution Niji Play Fist Accelerator, 19.30°C).

Precious metal fine particle adhesion treatment (22) Activator liquid (PdC120.01g/l, HCI
10ml (1.70°C) for 6 minutes.

Precious metal fine particle adhesion treatment (23) Activator liquid (chloroauric acid 0.3 g/l, HCI
4ml, 45°C) for 5.5 minutes.

Precious metal fine particle adhesion treatment (24) Activator liquid (silver sulfate 0.4 g/l, ammonia 0
．． 9ml, 40°C) for 6.5 minutes.

Precious metal fine particle adhesion treatment (25) Activator liquid (manufactured by Nippon Kanigen Co., Ltd., 1.10 times diluted,
45°C) for 4 minutes.

Precious metal fine particle adhesion treatment (26) Immersed in activator solution (3.4 times diluted with alkaline activator solution manufactured by Nippon Kanigen Co., Ltd., 40°C) for 4.5 minutes.

The numbers of the magnetic disk substrates thus obtained are designated as magnetic disk substrates 17 to 26 in correspondence with the noble metal fine particle adhesion processing numbers.

Electron microscopic observation of the surface of the obtained magnetic disk substrate (S
As a result of performing EM and TEM), the height was 0.08 pm.
It was observed that microprotrusions of ~0.1 pm were formed at a density of 3 or more per 511 m2. The size of the microprotrusions was 0.18 to 0.23 pm, and had the shape of a slightly flattened hemisphere. The microprotrusions were uniform in height, size, and shape, and were uniformly and densely formed on the surface of the magnetic disk substrate.

(Example 3) A magnetic disk substrate was produced in the same manner as in Example 1, but in this example, noble metal fine particle adhesion treatment was performed under the following conditions.
A magnetic disk substrate having the structure shown in FIG. 1 was formed.

Precious metal fine particle adhesion treatment (27) Sensitizer liquid (SnC1□l1g/l, HCI
After 1 minute immersion in activator solution (PdC 120, 35 g/l, HCl 15
m1/1.40°C) for 1 minute.

Precious metal fine particle adhesion treatment (28) Sensitizer liquid (SnC1□75g/l, Rochelle salt 110g/l, NaOH95g/I, 30°C)
After soaking for a minute, activator solution (chloroauric acid 2.5 g/l)
, HCI 5ml/1.45°C) for 1.5 minutes.

Precious metal fine particle adhesion treatment (29) Sensitizer liquid (SnC1210g/l, HCI 3
Activator solution (silver nitrate 2 g/l, ammonia 4 ml/l, 60°
Soak in C) for 1.5 minutes.

Precious metal fine particle adhesion treatment (30) After immersing in sensitizer solution (Pink Schumer, manufactured by Nippon Kanigen Co., Ltd., 7 times diluted, 35°C) for 0.5 minutes, activator solution (Red Schumer, manufactured by Nippon Kanigen Co., Ltd., diluted 2.5 times, 30°C) for 0.5 minutes.

Precious metal fine particle adhesion treatment (31) Catalytic treatment liquid (Liquid A: HCl 90ml/l → Water → PdC
1□ Colloidal liquid prepared in the order of 2.5g + SSnCl22H2O29 and adjusted to 10100O by adding water, 30'C
) for 70 seconds, then add the acceleration treatment solution (K solution: NH4BF
41 mol/l, 40'C) for 1 minute.

Precious metal fine particle adhesion treatment (32) Catalytic treatment liquid (D solution: HCl 370ml 1/1- + water-
+PdCl22g → 5nC1□2H2H2O6 After aging for 1 day, SSnCl22H2O48 was added in the prepared colloidal solution (25°C) for 0.5 minutes, and then the acceleration treatment solution (K solution: NH4BF41 mol/l) was added.

40°C) for 3 minutes.

Precious metal fine particle adhesion treatment (33) Catalytic treatment liquid (E' liquid Hydrochloric acid-based colloidal liquid Catalyst 9F manufactured by Niji Play First 3 volumes, hydrochloric acid 1 volume, water 2
After immersing it in a solution of 30°C for 90 seconds, the accelerator 19.
30°C) for 1 minute.

Precious metal fine particle adhesion treatment (34) Catalytic treatment liquid (F solution: 270g of Catalyst 404 dissolved in 840ml of water, and 45ml/l of salt-based colloidal liquid Catabosite 44 manufactured by Sibley Fyst)
The sample was immersed for 90 seconds in a solution added at the addition rate of 50'C), and then immersed in an acceleration treatment solution (M solution Niji Play Fist Accelerator, 19.30°C) for 1 minute.

Precious metal fine particle adhesion treatment (35) Activator liquid (PdC1z0.6g/l, HCI
30rnl/l, 60°C) for 1 minute.

Precious metal fine particle adhesion treatment (36) Activator liquid (chloroauric acid 1.3 g/l, HCI 4
ml/1.55°C) for 1.5 minutes.

Precious metal fine particle adhesion treatment (37) Activator liquid (silver nitrate 2.1 g/l, ammonia 3
ml/l, 40°C) for 1 minute.

Precious metal fine particle adhesion treatment (38) Activator liquid (acidic activating liquid manufactured by Nippon Kanigen Co., Ltd. 1.
3-fold dilution, 50°C) for 30 seconds.

Precious metal fine particle adhesion treatment (39) Activator liquid Acidic activation liquid 3.1 manufactured by Tamoto Kanigen Co., Ltd.
1-fold dilution, 60°C) for 1 minute.

The numbers of the magnetic disk substrates thus obtained are designated as magnetic disk substrates 27 to 39 in correspondence with the noble metal fine particle adhesion processing numbers.

Electron microscopic observation of the surface of the obtained magnetic disk substrate (S
As a result of performing EM and TEM), the height was 0.0611
It was observed that microprotrusions with a diameter of m to 0.08 pm were formed at a density of one or more per 111 m2. The size of the microprotrusions was 0.14 to 0.17 pm, and had the shape of a slightly flattened hemisphere. . The microprotrusions were uniform in height, size, and shape, and were uniformly and densely formed on the surface of the magnetic disk substrate.

(Comparative Example 1) A magnetic disk substrate was manufactured using the same procedure as in Example 3, but in this comparative example, the formation of each noble metal fine particle adhesion treatment performed on the mirror-polished base thick film surface was omitted. .

Let the number of the magnetic disk substrate thus obtained be (Hl).

Electron microscopic observation of the surface of the obtained magnetic disk substrate and measurement of surface roughness revealed that the surface was extremely smooth with no microprotrusions.

(Comparative Example 2) A magnetic disk substrate was manufactured in the same manner as in Comparative Example 1, but in this comparative example, after mirror polishing the surface of the base thick film,
Various abrasive grains (Mediball N35, N13, NO8,
...The grain sizes are 3.5 pm, 1.3 pm, 0.
8 pm) to change the surface roughness. Let the numbers of the magnetic disk substrates thus obtained be (in order: H2, H3, H4).

When the surface roughness of the obtained magnetic disk substrate was measured using a surface roughness meter, it was found that the roughness increased as the size of the abrasive grains increased. However, as a result of performing a surface electron microscope (magnification of 10,000 times or more) on the surface of the obtained magnetic disk substrate, it was found that the surface had scattered and disordered polishing streaks with thicknesses corresponding to various polishing abrasive grains, which became grooves. However, no microprotrusions were observed.

On the magnetic disk substrates obtained in Examples and Comparative Examples,
A film with a thickness of 0.0 mm was formed by electroless plating using plating bath (1).
A magnetic thin film of 0.08 pm was formed.

Plating bath (1) Plating bath composition Cobalt sulfate Nickel sulfate Sodium hypophosphite 0.07 mol/1 0.03 mol/1 0.21 mol/1 Sodium malonate 0.4 mol/1 Sodium malate 0.3 mol/1 succinic acid Sodium 0.4mol/1 ammonium sulfate
0.3 mol/1 plating condition Bath temperature 82°C Plating bath pH 9.3 (pH adjusted with aqueous ammonia at room temperature) Plating solution volume 1001 Next, silicic acid monomer was spin-coated on top of this, and the silicic acid monomer was coated at 190°C for 20 A thin protective film mainly composed of silicic acid polymer with a film thickness of 0.08 pm is formed by baking for a time, and a lubricating layer made of a liquid lubricant (perfluoroalkyl polyether) is further formed on this to create a magnetic disk. did. The numbers of the magnetic disks thus obtained are designated as magnetic disks 1 to 39 and magnetic disks H1 to H4, corresponding to the numbers of the magnetic disk substrates.

Next, regarding these magnetic disks, 3350 type Mn
-The presence or absence of head adsorption was investigated using a Zn ferrite magnetic head. A magnetic head and each disk were set up in a drive, and the coefficient of friction was measured before and after being left unused.

For the magnetic disks 1 to 39 using the magnetic disk substrate of the example, the coefficient of friction before being left is 0.2.
It was in the range of 0 to 0.30. The coefficient of friction tended to decrease as the height of the microprotrusions increased and the surface roughness increased, but any small value of 0.20 to 0.30 is a good value for practical use. The value of the coefficient of friction after being left for 100 hours was in the range of 0.21 to 0.28, and the magnetic disk using the magnetic disk substrate had no problem with respect to head adsorption. Regarding the magnetic disks using the magnetic disk substrate of the comparative example, the coefficient of friction before being left unused was 0.93 for the magnetic disk H1, 0.39 for the magnetic disk H2, 0.46 for the magnetic disk H3, and 0.0 for the magnetic disk H4. 7
It was 4. In the case of the magnetic disk H1 having the largest coefficient of friction, head adsorption became a problem even before it was left standing. 1
Examining the coefficient of friction after leaving it for 00 hours, it was found that the magnetic disk H
All of magnetic disks 1 to H4 increased to 1.0 or more, causing a head attraction phenomenon. Furthermore, regarding magnetic disks using the magnetic disk substrates of Examples and Comparative Examples,
C using C350 type Mn-Zn ferrite magnetic head
55 (contact/start/stop) test was conducted to determine the number of C8S cycles until scratches appeared on the surface. If this number of times is 20,000 times or more, it is considered to have sufficient durability for practical use. A scratch occurred on the surface of the magnetic disk H1 using the magnetic disk substrate of the comparative example after several hundred times, and C8838 occurred on the magnetic disk H2 using the magnetic disk substrate of the comparative example.
00 times, a head crash occurred at C882,400 times with magnetic disk H3, and C881,500 times with magnetic disk H4. Regarding magnetic disks 1 to 39 using the magnetic disk substrate of the example, no scratches were observed on the disk surface even after C8.88 million cycles, and the durability was significantly improved. Furthermore, the recording and reproducing characteristics of the magnetic disks using the magnetic disk substrates of Examples and Comparative Examples were compared. Since the magnetic disk H1 using the magnetic disk substrate of the comparative example uses a mirror-polished disk substrate, good recording and reproducing characteristics are obtained, and in this case, it can be considered as a standard disk serving as a reference. Magnetic disks 1 to 39 using magnetic disk substrates of examples
The characteristics of the output value, output envelope modulation, resolution, override, S/N, peak shift, and bit error are all the same as those of standard disks, and in the example, fine/h protrusions were added to the magnetic disk substrate. No effect was observed due to the formation. However, magnetic disks H2 to H4 using the magnetic disk substrate of Comparative Example 2 in which the surface roughness was increased by coarse abrasive grains were significantly inferior in each value of recording and reproducing characteristics compared to the standard disk. The recording and reproducing characteristics tended to deteriorate as the polishing roughness increased. Among the various values of recording and playback characteristics, output envelope modulation,
It was noticeable in S/N and bit errors. 20,000B
Looking at the recording and reproducing characteristics at PI (bits per inch) and 1000 TPI (racks per inch), standard disks have an S/N of 34 to 35 dB and less than 10 bit errors per side, whereas magnetic discs, for example, S on disk H2
/N20~22dB, bit-r-coo per side 55
It was inferior at 0 to 900 pieces. In the comparative example, we did not mention the texture processing in which polishing streaks are placed approximately in the circumferential direction (g), but the effect on head adsorption, durability, recording and playback characteristics, etc. is basically the same, just because the direction of the polishing streaks is different. Met. That is, when the polishing roughness was made to be the same as that of the comparative example, the same degree of deterioration in the mechanical properties as that of the comparative example was observed.

In the examples, only a plated disk was described in which a magnetic thin film was formed by plating and a protective film was formed by spin coating a silicate monomer, but metal sputter disks, ferrite sputter disks, and protective films in which magnetic thin films were formed by sputtering were also described. Similar studies were conducted on disks in which carbon or SiO2 was sputtered, and as a result, the same effects of the present invention as in the examples were found.

(Effects of the Invention) As shown above in the Examples and Comparative Examples, according to the present invention, a magnetic disk substrate is formed into a structure consisting of a base body and a large number of fine particles adhered to the surface of the base body. , many minute protrusions are formed on the surface, and the surface roughness required for the magnetic disk can be obtained. -; (4o). As a result, it is possible to obtain a magnetic disk with excellent durability by preventing adhesion to the magnetic head without impairing recording/reproducing characteristics (that is, without increasing signal errors or decreasing S/N).

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a magnetic disk substrate of the present invention. 1... Substrate, 2... Fine particles.

Claims (1)

[Claims] A magnetic disk substrate comprising a substrate and a large number of fine particles attached to the surface of the substrate.