WO2007099754A1

WO2007099754A1 - Substrate for magnetic recording medium and method for manufacturing such substrate

Info

Publication number: WO2007099754A1
Application number: PCT/JP2007/052226
Authority: WO
Inventors: Yoshiharu Masaki; Hajime Kobayashi; Hideki Kawai; Satoshi Nakano; Shigeru Hosoe
Original assignee: Konica Minolta Opto, Inc.
Priority date: 2006-03-03
Filing date: 2007-02-08
Publication date: 2007-09-07
Also published as: JP5062167B2; JPWO2007099754A1

Abstract

Provided is a substrate for a magnetic recording medium, by which adhesiveness between a coat layer formed on the substrate and the substrate is improved, while maintaining the coat layer smooth. The coat layer is formed on the surface of the substrate, and the coat layer is divided into a plurality of areas by concentric grooves and radial grooves. Since the coat layer is divided into areas, even when the expansion coefficient of the substrate is different from that of the coat layer, stress applied to the coat layer can be modified, and adhesiveness between the substrate and the coat layer is improved. Thus, generation of peeling and cracks of the coat layer can be prevented.

Description

Specification

Magnetic recording medium substrate and method for manufacturing the same

Technical field

TECHNICAL FIELD [0001] The present invention relates to a magnetic recording medium substrate used for a substrate of a magnetic disk recording apparatus and a method for manufacturing the same, and more particularly to a magnetic recording medium substrate using a nonmagnetic substrate whose surface is made of a resin. About.

Background art

[0002] Conventionally, an aluminum substrate or a glass substrate has been used for a magnetic disk recording device used in a computer or the like. A metal magnetic thin film is formed on the substrate, and information is recorded by magnetizing the metal magnetic thin film with a magnetic head.

[0003] Further, a magnetic head for reading magnetic recording information stored in a magnetic recording medium is configured to move in a state where the surface force of the magnetic recording medium floats. If there are irregularities on the surface of the magnetic recording medium, the irregularities and the magnetic head may collide with each other when the magnetic head moves, causing problems such as damage to the magnetic head and damage to the magnetic recording medium. In order to suppress the occurrence of such defects, the magnetic recording medium substrate is highly accurate during manufacture so that the surface thereof is a smooth surface! An attempt has been made to suppress the occurrence of surface irregularities as much as possible (for example, Patent Document 1, Patent Document 2, and Patent Document 3).

[0004] For example, when an aluminum substrate is used, the aluminum plate is press-molded into a disk shape and then polished with high precision on the surface! By applying a polishing process and a cleaning process, the surface is smoothed, and then a nickel-phosphorus (Ni-P) alloy is formed on the surface of the substrate by plating. After that, polishing and texturing are performed, and a magnetic layer of Co alloy is formed by sputtering to produce a magnetic recording medium.

[0005] When a glass substrate is used, a glass material is melted, and the molten glass is press-molded to produce a disk-shaped glass substrate. Then, the surface of the glass substrate is subjected to high-precision polishing IJ 'polishing and cleaning processes to smooth the surface, and then the surface is subjected to chemical strengthening treatment by ion exchange with an alkali molten salt, After the precision cleaning process, The magnetic recording medium is manufactured by applying a check and further forming a magnetic layer of a Co-based alloy by sputtering.

[0006] In a perpendicular magnetic recording medium, which is highly expected as a high-density technology, it is necessary to arrange magnetic materials perpendicular to the substrate surface. For this purpose, a soft magnetic layer is required between the magnetic layer and the substrate. Need to form. A typical alloy of this soft magnetic layer is a nickel-cobalt (Ni-Co) alloy, and a nickel-cobalt alloy is formed on the substrate surface by plating.

[0007] By the way, an attempt has been made to employ a resin substrate such as a plastic substrate as the magnetic recording medium substrate, and an attempt has been made to form a nickel alloy layer by plating the resin substrate. Yes. However, when a metal layer is formed on a plastic substrate by plating, the expansion coefficient differs between the plastic and the metal layer, so the metal layer may peel off or crack during or after the metal layer is formed. There is a problem that enters. For this reason, in order to improve the adhesion between the plastic substrate and the metal layer, the surface of the metal layer is roughened, and the metal layer is digged into the fine irregularities of the plastic substrate.

[0008] However, since the surface of the magnetic recording medium substrate is required to have smoothness, it is difficult to satisfy the smoothness required for the magnetic recording medium substrate when the surface of the metal layer is roughened. become.

Patent Document 1: Japanese Patent Laid-Open No. 2003-54965

Patent Document 2: Japanese Patent Laid-Open No. 2003-55001

Patent Document 3: Japanese Unexamined Patent Publication No. 2000-163740

Disclosure of the invention

Problems to be solved by the invention

[0009] The present invention solves the above-described problem, and for a magnetic recording medium capable of increasing the adhesion between the coating layer and the substrate while maintaining the coating layer formed on the substrate on a smooth surface. The purpose is to provide a board.

Means for solving the problem

[0010] The inventor of this application pays attention to the expansion coefficient of the substrate and the coating layer formed on the substrate, and divides the coating layer formed on the substrate surface into a plurality of regions. Coating layer and It has been found that the degree of adhesion can be increased.

[0011] In a first embodiment of the present invention, a nonmagnetic base material having a disk-like surface and a disc-like shape is used as a substrate, and a coating layer divided into a plurality of regions is formed on the surface. This is a substrate for a magnetic recording medium.

[0012] A second aspect of the present invention is a magnetic recording medium substrate according to the first aspect, characterized in that a plurality of regions are formed concentrically or Z and radially.

A third aspect of the present invention is a magnetic recording medium substrate according to the first aspect, wherein a plurality of regions are formed in a lattice shape.

[0014] A fourth aspect of the present invention is a magnetic recording medium substrate according to any one of the first to third aspects, wherein the plurality of regions have a polygonal shape. is there.

[0015] A fifth aspect of the present invention is a magnetic recording medium substrate according to any one of the first to fourth aspects, wherein the expansion coefficient of the substrate is A [ ^X10_5ZK ]. The area of each region of the coated layer is 1000 X (1 / A ² ) [mm ² ] or less.

[0016] A sixth aspect of the present invention is a magnetic recording medium substrate according to any one of the first to fifth aspects, wherein the thickness D of the coating layer, and the regions and regions of the divided coating layers The distance dl between and the following satisfies the relationship 100 X thickness D ≥ distance dl> thickness DZlO.

[0017] A seventh aspect of the present invention is a magnetic recording medium substrate according to any one of the first to sixth aspects, wherein the pattern of the region of the divided coating layer is chemical etching, physical It is formed by etching or physical / physical etching.

[0018] An eighth aspect of the present invention is a magnetic recording medium substrate according to any one of the first to sixth aspects, wherein the pattern of the divided coating layer region is represented by a stamper on the surface of the coating layer. After forming irregularities on the surface, it is formed by chemical etching, physical etching, or physicochemical etching.

[0019] A ninth aspect of the present invention is for a magnetic recording medium according to any one of the first to eighth aspects. The substrate is characterized in that the nonmagnetic base material is made of a resin.

[0020] A tenth aspect of the present invention is a substrate for a magnetic recording medium according to any one of the first to eighth aspects, wherein the nonmagnetic base material is made of glass or a nonmagnetic metal material. It is characterized by being.

In an eleventh aspect of the present invention, a coating layer is formed on a nonmagnetic substrate having a disk shape, and chemical etching, physical etching, or physicochemical etching is performed on the coating layer. According to another aspect of the present invention, there is provided a method for manufacturing a substrate for a magnetic recording medium, wherein the coating layer is divided into a plurality of regions by performing a chin.

[0022] In a twelfth aspect of the present invention, a coating layer is formed on a nonmagnetic substrate having a disk shape, and the surface of the coating layer is formed uneven by a stamper, and thereafter chemical etching, physical According to another aspect of the present invention, there is provided a method for manufacturing a substrate for a magnetic recording medium, in which a coating layer having projections and depressions is divided into a plurality of regions by performing physical etching or physical etching.

The invention's effect

[0023] According to the present invention, by dividing the coating layer formed on the substrate into a plurality of regions, even if the expansion coefficients of the substrate and the coating layer are different, excessive stress is applied to the coating layer. Therefore, the adhesion between the substrate and the coating layer can be increased.

Brief Description of Drawings

1 is a diagram showing a schematic configuration of a magnetic recording medium substrate according to an embodiment of the present invention. FIG. 1 (a) is a top view of the substrate, and FIG. 1 (b) is AA of the substrate. It is sectional drawing.

FIG. 2 is a top view of a substrate showing a modification of the magnetic recording medium substrate according to the embodiment of the present invention.

Explanation of symbols

[0025] 1, 10 Magnetic recording medium substrate

2 Board

3, 11, 20, 30 Coating layer

4A, 4B, 12, 21, 31 groove BEST MODE FOR CARRYING OUT THE INVENTION

A magnetic recording medium substrate according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a schematic configuration of a magnetic recording medium substrate according to an embodiment of the present invention. FIG. 1 (a) is a top view of the substrate, and FIG. 1 (b) is an AA view of the substrate. It is sectional drawing.

The substrate 2 has a disc shape and has a hole 5 in the center. A coating layer 3 is formed on the substrate 2 to form a magnetic recording medium substrate 1. The substrate 2 is made of a nonmagnetic material, and in this embodiment, a case where a resin is used as an example of the nonmagnetic material will be described.

[0028] As shown in the top view of FIG. 1 (a), the coating layer 3 is formed with concentric grooves 4A and radial grooves 4B. The grooves 4A and 4B allow the coating layer 3 to be divided into a plurality of regions. It is divided. As shown in the A—A cross-sectional view of FIG. 1 (b), in this embodiment, the width dl (interval between regions) of the groove 4A is equal, and the interval d2 between the groove 4A and groove 4A is also equal. It is summer. As for the radial groove 4B, the width dl (space between the areas) of the groove 4B is also equal, and the angle between the groove 4B and the groove 4B is also equal.

[0029] In this embodiment, three concentric grooves 4A are formed at equal intervals, and eight radial grooves 4B are formed every 45 °. The number of grooves 4A and 4B and the interval between the grooves are the same. May be appropriately changed depending on conditions such as the size of the substrate 2, the material of the substrate 2, or the material of the coating layer 3.

[0030] As described above, since the coating layer 3 is divided into a plurality of regions by the grooves 4A and 4B, the smoothness of the coating layer 3 is maintained without intentionally roughening the surface of the coating layer 3. On the other hand, the adhesion between the substrate 2 and the covering layer 3 can be increased. In other words, even if the expansion coefficients of the substrate 2 and the coating layer 3 are different, the coating layer 3 is divided into a plurality of regions, so that excessive stress is not applied during or after the coating layer 3 is formed. In addition, it is possible to prevent peeling of the coating layer 3 and generation of cracks.

Note that in this embodiment, even when the widths of the grooves 4A and 4B are equal, the degree of adhesion between the substrate 2 and the coating layer 3 can be increased. That is, the groove 4A and the groove 4B may have different widths, or the groove 4A and the groove 4B may have different widths. In addition, the interval between the grooves 4A may be different depending on the groove. May be different. In addition, since the grooves 4A and 4B divide the coating layer 3, the depths of the grooves 4A and 4B may be different if the depth of each of the grooves 4A and 4B is equal to or greater than the thickness D of the coating layer 3. May be.

[0032] In this embodiment, the force by which the covering layer 3 is divided into a plurality of regions by two types of grooves, concentric grooves 4A and radial grooves 4B, is formed by forming one of the grooves. The layer may be divided into a plurality of regions. Even in this case, it is possible to relax the stress applied to the coating layer and increase the adhesion between the coating layer and the substrate.

[0033] When the thickness D of the coating layer 3 formed on the substrate 2 is 100 [nm], the width dl (interval between the regions) of the grooves 4A and 4B is 1 [m] or less. U prefer that. This is because the width dl of the grooves 4A and 4B is preferably narrow in order to increase the recording capacity of the magnetic recording medium. Further, when the expansion coefficient of the substrate is A [X 10 ^_5 ZK], the area of each divided coating layer 3 is preferably 1 000 X (1ZA ² ) [mm ² ] or less. When A = 6, each divided area is preferably about 27.8 [mm ² ] or less. As a result, the degree of adhesion between the substrate 2 and the coating layer 3 can be increased, and the coating layer 3 can be prevented from peeling off from the substrate 2 or from being cracked.

[0034] Further, it is preferable that the thickness D of the coating layer 3 and the distance dl between the regions of the divided coating layer 3 satisfy the following expression.

[0035] 100 X thickness D ≥ spacing dl> thickness DZlO

Thereby, the area of the whole area | region of the coating layer 3 can be enlarged, and it can prevent that each area | region is connected.

[0036] Next, the material of the substrate 2 made of resin will be described. For the substrate 2, various types of resin can be used in addition to thermoplastic resin, thermosetting resin, or active ray curable resin.

[0037] For example, the substrate 2 made of resin has a thermoplastic resin, such as polycarbonate, polyetheretherketone resin (PEEK resin), cyclic polyolefin resin, methallyl styrene resin (MS resin), Polystyrene resin (PS resin), polyetherimide resin (PEI resin), ABS resin, polyester resin (PET resin, PBT resin, etc.), polyolefin resin (PE resin, PP resin, etc.) ), Polysulfone resin, polyethersulfone resin (PES resin), polyarylate resin, polyphenylene sulfide resin, polyamide resin, or acrylic resin Etc. can be used. Examples of thermosetting resins include phenol resin, urea resin, unsaturated polyester resin (BMC resin, etc.), silicon resin, urethane resin, epoxy resin, polyimide resin, polyamide Imido resin or polybenzimidazole resin can be used. In addition, polyethylene naphthalate resin (PEN resin) can be used!

[0038] As the actinic radiation curable resin, for example, an ultraviolet curable resin is used. Examples of the ultraviolet curable resin include, for example, an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, Examples thereof include an ultraviolet curable epoxy resin, an ultraviolet curable silicon resin, and an ultraviolet curable acrylic resin.

[0039] In addition, when curing is performed by irradiating the coated layer before curing with active rays, it is preferable to accelerate the curing reaction using a photoinitiator. At this time, a photosensitizer may be used in combination.

[0040] When oxygen in the air suppresses the curing reaction, active rays can be irradiated, for example, in an inert gas atmosphere in order to reduce or remove the oxygen concentration. As the actinic ray, infrared rays, visible light, ultraviolet rays, and the like can be appropriately selected. However, ultraviolet rays are particularly preferred, but are not particularly limited. In addition, the curing reaction may be strengthened by heating during active ray irradiation or before and after.

[0041] Further, the substrate 2 made of resin may use a liquid crystal polymer, an organic Z inorganic hybrid resin (for example, a polymer component incorporating silicon as a skeleton), or the like. Note that the resin listed above is an example of the resin used for the substrate 2, and the substrate according to the present invention is not limited to these resins. Two or more types of resin can be mixed to form a resin substrate, or different components can be adjacent to each other as separate layers.

[0042] A method of manufacturing the substrate 2 made of resin is performed by using a mold having a shape corresponding to the substrate 2, using an injection molding method, a casting molding method, a sheet molding method, an injection compression molding method, or a compression molding method. It can be produced by a forming method such as a method. Furthermore, if necessary, the substrate 2 may be manufactured by cutting, punching, or press-molding the formed substrate.

[0043] Further, by molding the substrate 2 by the injection molding method or the like, the dimensions of the inner diameter of the substrate 2, the outer At least one of the size of the diameter, the shape of the inner peripheral end, or the shape of the outer peripheral end can be formed simultaneously. In other words, molds used in the injection molding method, etc., are manufactured in accordance with the inner and outer diameter dimensions of the substrate 2, and the inner and outer diameter dimensions are completed during resin molding by using these molds. Will be. In addition, a mold is prepared according to the shape of the inner peripheral end of the substrate 2 and the shape of the outer peripheral end, and by using the mold, the shape of the inner peripheral end and the shape of the outer peripheral end are reduced. It will be formed at the time of molding.

[0044] As the coating layer 3, a metal layer, a ceramic layer, a magnetic layer, a glass layer, or a composite layer (hybrid layer) of an inorganic layer and an organic layer is used. Specific components of the coating layer include Ni (nickel), Fe (iron), Cu (copper), Ti (titanium), P (phosphorus), Co (cobalt), Si (silicon), Sn (tin) or Pd (palladium) and the like are included.

[0045] The coating layer 3 can be formed on the surface of the substrate 2 by a plating method such as electric plating or chemical plating. In addition, it can be formed by sputtering, vacuum deposition, CVD method, or the like. Also, a coating method such as a bar coating method, a dip coating (dipping and pulling up) method, a spin coating method, a spray method, or a printing method can be used.

[0046] After the coating layer 3 is formed on the surface of the substrate 2 by plating or the like, a resist is formed on the coating layer 3, and a pattern is formed on the resist with a mask corresponding to the grooves 4A and 4B, and electron beam exposure is performed. Etch with FIB or FIB to form grooves 4A and 4B. Thereafter, the resist on the substrate is peeled off to obtain a magnetic recording medium substrate 1. In this way, the coating layer 3 can be divided into a plurality of regions according to the patterning process.

[0047] Examples of the etching method include chemical etching, physical etching, and physicochemical etching. Chemical etching is a method of selectively etching a removal target using a chemical reaction. Physical etching is a method of etching an object to be removed by causing accelerated argon ions to collide with the surface to be etched. An example of physical etching is ion milling. In addition, physicochemical etching is a method in which anisotropic etching is performed by using a chemical reaction between radicals (activated molecules and atoms having no charge) and a material to be etched and ion irradiation. Examples of physical chemical etching include RIE (Reactive Ion Etching).

[0048] Further, after forming irregularities on the surface of the coating layer with a stamper, chemical etching, The grooves 4A and 4B may be formed by physical etching or physical etching.

When producing a magnetic recording medium using this magnetic recording medium substrate 1, a magnetic layer such as a Co-based alloy is formed on the surface of the magnetic recording medium substrate 1 by sputtering or the like. And

[0050] Further, in a perpendicular magnetic recording medium that is highly expected as a high-density technology, it is necessary to arrange magnetic materials perpendicular to the substrate surface. For this purpose, a soft magnetic layer is required between the magnetic layer and the substrate. Need to form. A typical alloy for this soft magnetic layer is a nickel-cobalt (Ni-Co) alloy. By using a Ni—Co alloy as the covering layer 3, it can also function as a soft magnetic layer in a perpendicular magnetic recording medium.

[0051] Further, it is desirable that the resin as a base material has a heat-resistant temperature or a glass transition temperature Tg as high as possible. Since the magnetic layer is formed on the resin substrate 2 by sputtering, it is desirable that the heat resistant temperature or the glass transition temperature Tg is equal to or higher than the sputtering temperature. For example, it is desirable to use a resin having a heat resistant temperature or a glass transition temperature Tg of 200 ° C or higher.

[0052] Representative resins having a glass transition temperature Tg of 200 ° C or higher include polyethersulfone resin (PES resin), polyetherimide resin (PEI resin), polyamideimide resin, and polyimide resin. , Polybenzimidazole resin, BMC resin, or liquid crystal polymer. More specifically, polyethersulfone resin (PES resin), Udel (Solve Devast Polymers), polyetherimide resin (PEI resin), Ultem (Japan GE Plastics), polyamideimide As resin, Torlon (Solveia Devast Polymers), polyimide resin (thermoplastic), Aurum (Mitsui Chemicals), polyimide (thermosetting), Upilex (Ube Industries), or polybenzimidazole PBlZCelazol e (Clariant Japan) is an example of rosin. In addition, liquid crystal polymers include SUMIKASUPER LCP (Sumitomo Chemical), and polyether ether ketones as Victrex (Victrex MC).

[0053] In addition, it is desirable to use a resin having a low hygroscopic property as the resin substrate 2 in order to prevent displacement from the magnetic head due to a dimensional change of the substrate due to moisture absorption. Typical examples of resins with low hygroscopicity include polycarbonate and cyclic polyolefin resin. [0054] Further, the above description has been made by taking an example in which the substrate is made of a single resin, but the substrate is not limited to being made of a single resin, and may be made of metal or It may be configured by coating the surface of a non-magnetic material such as glass with a resin layer. In this case, as the nonmagnetic material coated with the resin, various materials applicable as a substrate such as a resin, metal, ceramics, glass, glass ceramics, or an organic-inorganic composite material can be used.

[0055] Note that it is preferable that the substrate is composed of a single resin because the manufacturing process can be simplified.

[0056] An example of the division of the coating layer 3 in the magnetic recording medium substrate 1 according to this embodiment is one example, and the present invention is not limited to the division example shown in FIG. Here, a modification of the magnetic recording medium substrate according to the above embodiment will be described with reference to FIG. FIG. 2 is a top view showing a modification of the magnetic recording medium substrate according to the embodiment of the present invention. (Modification 1)

Modification 1 will be described with reference to FIG. For example, as shown in FIG. 2 (a), a magnetic recording medium substrate 10 according to Modification 1 includes a coating layer that is divided into a lattice pattern by grooves 12 on a substrate of a nonmagnetic material such as grease. 11 is formed. That is, the individual coating layers 11 after the division have a quadrangular shape. The width of the groove 12 is equal, and the distance between the groove 12 and the groove 12 is also equal. The number of the grooves 12 and the interval between the grooves 12 may be appropriately changed depending on conditions such as the size and material of the substrate.

[0057] As described above, the coating layer 11 is divided into a plurality of regions by the grooves 12, so that the smoothness of the coating layer 11 is maintained without intentionally roughening the coating layer 11, and the substrate and It becomes possible to increase the degree of adhesion with the coating layer 11. Although the grooves 12 have the same width, even if the grooves 12 have different widths, the adhesion between the substrate and the coating layer 11 can be increased. Further, the interval between the groove 12 and the groove 12 may be different depending on the groove. Furthermore, the area of each coating layer 11 may be the same or different depending on the location. The conditions of the width of the groove 12 and the area of each divided covering layer 11 are the same as the conditions according to the above embodiment. (Modification 2)

Next, Modification 2 will be described with reference to FIG. Fig. 2 (b) shows a magnetic recording medium. Enlarge and show a part of the board! In the magnetic recording medium substrate according to the second modification, a coating layer 20 divided into hexagonal shapes by grooves 21 is formed on a substrate of a nonmagnetic material such as resin. The widths of the grooves 21 are equal, and the areas of the individual coating layers 20 after division are also equal.

As described above, since the coating layer 20 is divided into a plurality of regions by the grooves 21, the degree of adhesion between the substrate and the coating layer 20 can be increased. In addition, even if the width of each groove 21 is different, the degree of adhesion between the substrate and the coating layer 20 can be increased. Further, the area of each coating layer 20 may be the same or different depending on the location. The conditions of the width of the groove 21 and the area of each divided covering layer 20 are the same as the conditions according to the above embodiment.

(Modification 3)

Next, Modification 3 will be described with reference to FIG. Figure 2 (c) shows a magnified part of the magnetic recording medium substrate! In the magnetic recording medium substrate according to Modification 3, a coating layer 30 divided into a triangular shape by grooves 31 is formed on a substrate of a nonmagnetic material such as a resin. The widths of the grooves 31 are equal, and the areas of the individual coating layers 30 after division are also equal.

As described above, since the covering layer 30 is divided into a plurality of regions by the grooves 31, it is possible to increase the degree of adhesion between the substrate and the covering layer 30. In addition, even if the width of each of the grooves 31 is different, the adhesion between the substrate and the coating layer 30 can be increased. Further, the area of each coating layer 30 may be the same or different depending on the location. The conditions of the width of the groove 31 and the area of each divided covering layer 30 are the same as the conditions according to the above embodiment.

[0060] As described in Modification 1 to Modification 3, even when the coating layer is divided into a triangular shape, a quadrangular shape, or a hexagonal shape, the adhesion between the substrate and the coating layer can be increased. As a result, it is possible to prevent the covering layer from peeling off or cracking. In addition, the shape of the covering layer is not limited to a triangular shape or a quadrangular shape, and even if the covering layer is divided into polygons of octagons or more, peeling of the covering layer and occurrence of cracks can be prevented. In addition, the shape of the individual coating layers divided by the grooves is not limited to the above-described embodiment or modification, and may be a trapezoidal shape or a rounded shape. The same effect can be achieved.

[Example]

Next, specific examples according to the embodiment of the present invention will be described.

(Example 1)

In Example 1, a specific example of the magnetic recording medium substrate 1 shown in FIG. 1 will be described. In Example 1, as shown in FIG. 1, the coating layer 3 divided by the concentric grooves 4A and the radial grooves 4B is formed on the substrate 2, and the degree of adhesion between the substrate 2 and the coating layer 3 is confirmed. did. (Substrate 2 molding)

Polyimide was used as a substrate material, and a resin substrate 2 was produced by injection molding. Aurum (made by Mitsui Engineering Co., Ltd.) was used as a polyimide. The dimensions of this substrate 2 are shown below.

[0061] Outer diameter: 21.6 [mm]

Hole diameter: 6 [mm]

Substrate 2 thickness: 0.4 [mm]

Board expansion coefficient A: 4.7 X 10 ^_5 ZK

(Deposition of coating layer 3)

A Ni layer was formed on the surface of the substrate 2 by sputtering the substrate 2. Thereafter, further, sputtering was performed to form a nickel-phosphorus (Ni—P) alloy layer (hereinafter referred to as “NiP layer”) on the Ni layer. The thickness of this NiP layer was 10 [nm]. These Ni layer and NiP layer correspond to the coating layer 3 formed on the substrate 2.

(Formation of grooves 4A and 4B)

After the coating layer 3 is formed on the surface of the substrate 2, a resist is formed on the coating layer 3, a pattern is formed on the resist with a mask corresponding to the grooves 4A and 4B, and the groove is formed in the coating layer 3 by etching. 4A and 4B were formed.

[0062] The dimensions of the coating layer 3 and the grooves 4A and 4B are shown below.

[0063] Width of groove 4A (11: 1 [/ ζ πι]

Distance between grooves 4 mm d2: 3 [mm]

Width of groove 4B dl: l [m]

Angle between grooves 4B: 45 [°] Maximum area of cover layer 3 after division: 21.9 [mm ² ]

Here, as described above, since the preferable area of each divided coating layer 3 is 1000 X (l ZA ² ) [mm ² ] or less, the maximum area of the coating layer 3 after the division is 45. 3mm ² or less is preferable. In this example, the maximum area of the coating layer 3 after division is 21.9 mm ² as described above, which is a preferable area range.

(Evaluation)

A coating layer 3 was formed on a resin substrate 2 and the coating layer 3 was divided into a plurality of regions, and then the adhesion between the substrate 2 and the coating layer 3 was evaluated. Here, the test method and evaluation method for the degree of adhesion will be described. A heat cycle test was conducted in which the substrate 2 (test sample) on which the coating layer 3 was formed was alternately put in and out of a high temperature bath maintained at 60 ° C. and a refrigerator chamber maintained at 5 ° C. Here, alternating turns were repeated 10 times. Thus, by applying a rapid temperature difference to the test sample, thermal damage due to the difference in linear thermal expansion between the substrate 2 and the coating layer 3 was given to the test sample. The test samples were placed in a high-temperature bath and a refrigerator compartment for 10 minutes respectively, and the replacement from the high-temperature vessel to the refrigerator compartment and the change from the refrigerator compartment to the high-temperature vessel were performed within 10 seconds. In the evaluation after the heat cycle test, the surface of the coating layer 3 was visually observed and observed with an optical microscope, and it was confirmed whether the coating layer 3 was cracked, peeled or lifted.

[0064] In Example 1, it was confirmed that the covering layer 3 had a high degree of adhesion between the substrate 2 and the covering layer 3 without peeling off from the substrate 2 or causing cracks in the covering layer 3.

In Example 1, polyimide is used as the material for the substrate 2 made of resin, but the same effect can be obtained by using other resins described in the above embodiment. Further, the same effect can be obtained by laminating a layer having another component force such as a nickel-cobalt layer having a NiP layer as a coating layer.

(Example 2)

In Example 2, a specific example of the magnetic recording medium substrate 1 shown in FIG. In Example 2, the dimensions of the individual coating layers 3 after the division were changed by changing the dimensions of the grooves 4A and 4B. The same resin (polyimide) as in Example 1 was used for the resinous substrate 2 according to Example 2. (Board 2 dimensions)

Outer diameter: 27.4 [mm]

Hole diameter: 7 [mm]

Substrate 2 thickness: 0.4 [mm]

(Deposition of coating layer 3)

In Example 2, similarly to Example 1, a Ni layer and a NiP layer were formed as a coating layer 3 on a resin substrate 2 and the coating layer 3 was etched to be divided into a plurality of regions.

[0066] The dimensions of the coating layer 3 and the grooves 4A and 4B are shown below.

[0067] Width of groove 4A (11: 1 [/ ζ πι]

Distance between grooves 4 mm d2: 2 [mm]

Width of groove 4B dl: l [m]

Angle between grooves 4B: 45 [°]

Maximum area of coating layer 3 after division: 20.0 [mm ² ]

Here, the maximum area of the divided coating layer 3 in this example is 20.0 mm ² as described above, which is a preferable area range as in Example 1.

(Evaluation)

A coating layer 3 was formed on a resin substrate 2 and the coating layer 3 was divided into a plurality of regions, and then the adhesion between the substrate 2 and the coating layer 3 was evaluated by the same method as in Example 1. Also in this Example 2, it was confirmed that the coating layer 3 had a high degree of adhesion between the substrate 2 and the coating layer 3 without peeling off from the substrate 2 or cracking in the coating layer 3. .

(Example 3)

In Example 3, a specific example of the magnetic recording medium substrate 1 shown in FIG. In Example 3, the dimensions of the individual coating layers 3 after the division were changed by changing the dimensions of the grooves 4A and 4B. The same resin (polyimide) as in Example 1 was used for the resin substrate 2 according to Example 3.

(Board 2 dimensions)

Outer diameter: 27.4 [mm]

Hole diameter: 7 [mm] Substrate 2 thickness: 0.4 [mm]

(Formation of coating layer 3)

In Example 3, as in Example 1, a Ni layer and a NiP layer were formed as the coating layer 3 on the resin substrate 2 and the coating layer 3 was etched to be divided into a plurality of regions.

[0068] The dimensions of the coating layer 3 and the grooves 4A and 4B are shown below.

[0069] Width of groove 4A (11: 1 [/ ζ πι]

Distance between grooves 4 mm d2: 3 [mm]

Width of groove 4B dl: l [m]

Angle between grooves 4B: 30 [°]

Maximum area of covering layer 3 after division: 19.2 [mm ² ]

Here, the maximum area of the coating layer 3 after division in this example is 19.2 mm ² as described above, which is a preferable area range as in Example 1.

(Evaluation)

A coating layer 3 was formed on a resin substrate 2 and the coating layer 3 was divided into a plurality of regions, and then the adhesion between the substrate 2 and the coating layer 3 was evaluated by the same method as in Example 1. In Example 3 as well, it was confirmed that the coating layer 3 was not peeled off from the substrate 2 or cracked in the coating layer 3, and the adhesion between the substrate 2 and the coating layer 3 was high. .

(Comparative example)

Next, a comparative example for Example 1 to Example 3 will be described. In this comparative example, a Ni layer and a NiP layer were formed as coating layers on a resin-made (polyimide) substrate. In this comparative example, the degree of adhesion between the substrate and the coating layer was evaluated without dividing the coating layer into a plurality of regions.

(Board dimensions)

Outer diameter: 27.4 [mm]

Hole diameter: 7 [mm]

Substrate thickness: 0.4 [mm]

Cover layer thickness: 10 [nm]

In this comparative example, since the coating layer is not divided into a plurality of regions, the area of the coating layer is 46. 8 mm ² , which is outside the preferred area range.

(Evaluation)

After forming the coating layer on the resin-made substrate, the degree of adhesion between the substrate and the coating layer was evaluated by the same method as in Examples 1 to 3. In this comparative example, peeling or cracking of the coating layer was confirmed. As described above, since the coating layer is not divided into a plurality of regions, excessive stress is applied to the coating layer due to different expansion coefficients of the substrate and the coating layer, and the coating layer peels off from the substrate cover. It is thought that cracks occurred in the coating layer.

[0070] As in Example 1 to Example 3, by dividing the coating layer into a plurality of regions, it is possible to relieve the stress applied to the coating layer and prevent the coating layer from peeling or cracking. Become. (Example 4)

In Example 4, a specific example of the magnetic recording medium substrate 10 shown in FIG. 2A will be described. In Example 4, as shown in FIG. 2 (a), the lattice-shaped coating layer 11 divided by the grooves 12 was formed on the substrate. The same resin (polyimide) as in Example 1 was used for the resin substrate according to Example 4.

(Board dimensions)

Outer diameter: 21.6 [mm]

Hole diameter: 6 [mm]

Substrate thickness: 0.4 [mm]

(Deposition of coating layer 11)

In Example 4, similarly to Example 1, a Ni layer and a NiP layer were formed as a coating layer 11 on a resin substrate, and the coating layer 11 was etched to be divided into a plurality of regions.

[0071] The dimensions of the coating layer 11 and the groove 12 are shown below.

[0072] Width of groove 12: 1 [/ ζ πι]

Distance between grooves 12: 3 [mm]

Maximum area of the coating layer 11 after division: 9 [mm ² ]

Here, the maximum area of the divided coating layer 11 in this example is 9 mm ² as described above, which is a preferable area range as in Example 1. (Evaluation)

After the coating layer 11 was formed on the resin substrate and the coating layer 11 was divided into a plurality of regions, the adhesion between the substrate and the coating layer 11 was evaluated by the same method as in Example 1. In Example 4 as well, it was confirmed that the coating layer 11 was strong in peeling off the substrate force and cracked in the coating layer 11, and the adhesion between the substrate and the coating layer 11 was high.

(Example 5)

In Example 5, a specific example of the magnetic recording medium substrate 10 shown in FIG. In Example 5, the dimensions of the individual coating layers 11 after the division were changed by changing the dimensions of the grooves 12. The same resin (polyimide) as in Example 1 was used as the resin substrate according to Example 5.

(Board dimensions)

Outer diameter: 27.4 [mm]

Hole diameter: 7 [mm]

Substrate thickness: 0.4 [mm]

(Deposition of coating layer 11)

In Example 5, similarly to Example 1, a Ni layer and a NiP layer were formed as a coating layer 11 on a resin substrate, and the coating layer 11 was etched to be divided into a plurality of regions.

[0073] The dimensions of the coating layer 11 and the groove 12 are shown below.

[0074] Width of groove 12: 1 [/ ζ πι]

Distance between grooves 12: 4 [mm]

Maximum area of the coating layer 11 after division: 16 [mm]

Here, the maximum area of the divided coating layer 11 in this example is 16 mm ² as described above, which is a preferable area range as in Example 1.

(Evaluation)

After the coating layer 11 was formed on the resin substrate and the coating layer 11 was divided into a plurality of regions, the adhesion between the substrate and the coating layer 11 was evaluated by the same method as in Example 1. Also in this Example 5, the coating layer 11 peels off the substrate, and the coating layer 11 is cracked. It was confirmed that the adhesion between the substrate and the coating layer 11 was high.

(Example 6)

In Example 6, as in Example 4, a specific example of the magnetic recording medium substrate 10 shown in FIG. In Example 6, the dimensions of the individual coating layers 11 after the division were changed by changing the dimensions of the grooves 12. The same resin (polyimide) as in Example 1 was used as the resin substrate according to Example 5.

(Board dimensions)

Outer diameter: 27.4 [mm]

Hole diameter: 7 [mm]

Substrate thickness: 0.4 [mm]

(Deposition of coating layer 11)

In Example 6, as in Example 1, a Ni layer and a NiP layer are formed as a coating layer 11 on a resin substrate, and the coating layer 11 is etched to be divided into a plurality of regions. did.

[0075] The dimensions of the coating layer 11 and the groove 12 are shown below.

[0076] Width of groove 12: 1 [/ ζ πι]

Distance between grooves 12: 5 [mm]

Maximum area of the coating layer 11 after division: 25 [mm ² ]

Here, the maximum area of the divided coating layer 11 in this example is 25 mm ² as described above, which is a preferable area range as in Example 1.

(Evaluation)

After the coating layer 11 was formed on the resin substrate and the coating layer 11 was divided into a plurality of regions, the adhesion between the substrate and the coating layer 11 was evaluated by the same method as in Example 1. In Example 6 as well, it was confirmed that the coating layer 11 had a strong adhesion between the substrate and the coating layer 11 without causing the substrate force to peel off or cracking in the coating layer 11.

As described above, as in Example 4 to Example 6, by dividing the coating layer into a plurality of regions, stress applied to the coating layer can be relaxed, and peeling of the coating layer and generation of cracks can be prevented. Possible Even in the case of a magnetic recording medium substrate that does not meet the conditions described in Example 1 to Example 6, the coating layer formed on the resin substrate is divided into a plurality of regions so that the substrate and the substrate are covered. It was confirmed that the degree of adhesion with the covering layer can be increased. For example, as shown in FIG. 2 (b), the individual covering layers 20 are divided into hexagonal shapes, and as shown in FIG. 2 (c), the individual covering layers 30 are divided into triangular shapes. However, it was confirmed that the stress applied to the coating layer can be relaxed, and as a result, the peeling of the coating layer and the occurrence of cracks can be prevented.

Claims

The scope of the claims

[1] A magnetic recording characterized in that the surface is made of a resin, a non-magnetic base material having a disk shape is used as a substrate, and a coating layer divided into a plurality of regions is formed on the surface. Medium substrate.

[2] The magnetic recording medium substrate according to [1], wherein the plurality of regions are formed concentrically, Z, and radially.

3. The magnetic recording medium substrate according to claim 1, wherein the plurality of regions are formed in a lattice shape!

[4] The magnetic recording medium substrate according to any one of claims 1 to 3, wherein the plurality of regions have a polygonal shape.

[5] When the expansion coefficient of the substrate is A [X 10 " ⁵ / K], the area of each of the divided coating layers is 1000 X (1 / A ² ) [mm ² ] or less. The magnetic recording medium substrate according to any one of claims 1 to 4, wherein the magnetic recording medium substrate is provided.

[6] The thickness D of the coating layer and the distance dl between the divided coating layer regions are as follows:

100 X thickness D ≥ distance dl> thickness DZlO

The magnetic recording medium substrate according to any one of claims 1 to 5, wherein the following relationship is satisfied.

[7] The pattern of the region of the divided covering layer is formed by chemical etching or physical etching.

7. The magnetic recording medium substrate according to claim 1, wherein the magnetic recording medium substrate is formed by physical etching.

[8] The pattern of the region of the divided coating layer is formed by chemical etching, physical etching, or physical etching after forming concaves and convexes on the surface of the coating layer with a stamper. The magnetic recording medium substrate according to any one of claims 1 to 6, wherein the force is any one of claims 1 to 6.

[9] The magnetic recording medium substrate according to any one of [1] to [8], wherein the nonmagnetic base material is made of a resin.

10. The magnetic recording medium according to any one of claims 1 to 8, wherein the nonmagnetic base material is made of glass or a nonmagnetic metal material. Substrate.

[11] A coating layer is formed on a nonmagnetic substrate having a disk shape,

A method for manufacturing a substrate for a magnetic recording medium, wherein the coating layer is divided into a plurality of regions by subjecting the coating layer to chemical etching, physical etching, or physicochemical etching. .

[12] A coating layer is formed on a nonmagnetic substrate having a disk shape,

The surface of the coating layer is formed uneven by a stamper,

Thereafter, chemical etching, physical etching, or physical etching is performed to divide the coating layer on which the irregularities are formed into a plurality of regions, and the substrate for a magnetic recording medium Manufacturing method.