JP2005203078A - Method for manufacturing substrate for magnetic recording medium, substrate for magnetic recording medium, and magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a substrate for a magnetic recording medium, which has a satisfactory plating thickness, adhesion, and uniformity and which can form a plating layer having satisfactory smoothness on a nonmagnetic substrate by an electroless plating method, when a glass substrate is used as the nonmagnetic substrate. <P>SOLUTION: The method includes: a washing step S1 for washing the surface of the nonmagnetic substrate; a Ni adhesion layer forming step S2 for forming a Ni adhesion layer bonded to the surface of the nonmagnetic substrate after the washing; a Pd catalyst layer forming step S3 for forming a Pd catalyst layer bonded to the surface of the Ni adhesion layer; and a plating layer forming step S4 for forming the Ni-P plating layer on the surface of the Pd catalyst layer, as the catalyst, by the electroless plating method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a magnetic recording medium substrate, and a magnetic recording medium substrate and a magnetic recording medium manufactured by using the manufacturing method, and more particularly to a non-magnetic substrate using a glass substrate and electroless plating on the surface thereof. The present invention relates to a pre- and post-processing method when forming a Ni-P layer by the method, and is suitable for use as a substrate of a magnetic recording medium mounted on a hard disk device (HDD).

In recent years, hard disk devices are often used as storage devices for computers, digital home appliances, and the like. In general, a magnetic disk (hard disk) as a magnetic recording medium mounted on a hard disk device has a Ni-P layer formed on the surface of a disk-like nonmagnetic substrate by electroless plating, and the surface of the Ni-P layer is formed. A substrate for a magnetic disk is manufactured by performing necessary smoothing processing, texturing processing, etc., and a nonmagnetic metal underlayer, a magnetic recording layer of a ferromagnetic alloy thin film, a protective layer, and a liquid lubricant layer are formed on the substrate. It is produced by forming sequentially.
Conventionally, an aluminum alloy has been used as a material for a non-magnetic substrate. In recent years, the increase in capacity, size, and weight of hard disk drives has been rapidly progressing. Correspondingly, magnetic disks have higher flatness than conventional ones, and small-diameter and thin-type ones have been required. Conventional substrates made of aluminum alloys are difficult to respond to such market demands, and glass is being used as a substrate material.

By the way, even when using a glass substrate, it is desired to form a Ni-P layer on the surface to have the same surface characteristics as in the case of an aluminum alloy substrate in order to obtain a magnetic disk with good characteristics. However, it is technically difficult to form a Ni-P layer uniformly and smoothly on a glass substrate by electroless plating, and various methods are available as pre- and post-electroless plating processes to solve the problem. Proposed.
For example, a method of performing electroless plating after treating with an aqueous solution containing palladium chloride and stannous chloride and then treating with an aqueous alkali carbonate solution, an aqueous alkali hydrogen carbonate solution, or a mixed aqueous solution of both (see, for example, Patent Document 1) , Two-step etching treatment with chromic acid-sulfuric acid mixed solution and nitric acid solution, then etching with strong alkaline solution, sensitization treatment with dilute stannous chloride, and activation treatment with silver salt solution and palladium salt solution After electroless plating (see, for example, Patent Document 2), cleaning with warm solution of sulfuric acid and potassium dichromate, sensitization with stannous chloride acidified with hydrochloric acid, then palladium chloride solution After the activation, the method of performing electroless plating (see, for example, Patent Document 3), alkali degreasing, etching with hydrofluoric acid, Sensitization with a solution of tin, then after activation with a solution of palladium chloride, and a method of performing electroless plating has been proposed.

In addition, as a pre-treatment, the glass substrate is first thoroughly degreased, and then etched to enhance the anchor effect, remove foreign substances generated during etching and adhere to the substrate surface, and perform a surface conditioning process to chemically modify the substrate surface. A method of performing electroless Ni-P plating after performing sensitizing processing and activation processing subsequently (see, for example, Patent Document 4) is disclosed. As an etchant, it is preferable to use an aqueous solution containing hydrofluoric acid and potassium hydrogen fluoride, to remove hydrochloric acid for surface foreign matter removal, and to use an aqueous solution containing sodium methoxide for surface adjustment.
Further, as a pretreatment on the surface of the glass substrate, degreasing treatment, etching treatment, warm pure water treatment, silane coupling agent treatment, activator treatment, accelerator treatment are sequentially performed, followed by electroless Ni-P plating, A method of performing heat treatment (see, for example, Patent Document 5) is disclosed. It is preferable to use an aminosilane coupling agent as the silane coupling agent, a palladium chloride aqueous solution as the activator, and a sodium hypophosphite aqueous solution as the accelerator.
Japanese Patent Laid-Open No. 1-176079 Japanese Patent Laid-Open No. 53-19932 JP-A-48-85614 Japanese Patent Laid-Open No. 7-334841 JP 2000-163743 A

However, in the Ni-P plating layer formed on the glass substrate by the known method as described above, a sufficient film thickness (film thickness of 1 μm to several μm) necessary to obtain a magnetic disk with good characteristics and It was not possible to satisfy sufficient adhesion, uniformity and smoothness with the film thickness.
Therefore, in view of the above points, the present invention provides a plating layer having sufficient plating film thickness, adhesion, uniformity and sufficient smoothness when a glass substrate is used as the nonmagnetic substrate. It is an object of the present invention to provide a method of manufacturing a magnetic recording medium substrate that can be formed on a nonmagnetic substrate by electroless plating, a magnetic recording medium substrate and a magnetic recording medium manufactured using the manufacturing method. To do.

In order to achieve the above-described object, a method for manufacturing a magnetic recording medium substrate according to the present invention forms a cleaning step for cleaning the surface of a nonmagnetic substrate and a Ni adhesion layer bonded to the surface of the nonmagnetic substrate after cleaning. Ni adhesion layer forming step, Pd catalyst layer forming step for forming a Pd catalyst layer bonded to the surface of the Ni adhesion layer, and plating layer formation for forming a plating layer on the surface using the Pd catalyst layer as a catalyst by an electroless plating method And a process.
Here, the non-magnetic substrate is made of a glass substrate, and the cleaning step includes a step of performing a degreasing process on the surface of the glass substrate and a step of performing an activation process on the surface of the degreased glass substrate. In the layer forming step, the Ni chelating agent or Ni soap agent is applied to the surface of the activated glass substrate, and the applied Ni chelating agent or Ni soap agent is metallized and fired to form a Ni metal film. And forming the Ni metal film into the Ni adhesion layer by applying an activation process to the surface of the Ni metal film. The Pd catalyst layer forming process includes the step of forming the Ni metal film subjected to the activation process. It comprises a Pd catalyst treatment step in which Pd is bonded to the surface to form a Pd catalyst layer. The plating layer formation step includes a step of forming a plating film on the surface by an electroless plating method using the Pd catalyst layer as a catalyst. It can be made and a step of the plating layer is subjected to heat treatment to come film.

In addition, the Ni chelating agent can have a structure represented by the following general formula (1).
Ni (C _i H _{2i + 1} COC _j H _2j COC _k H _{2k + 1} ) (1)
(Where i, j and k are positive integers)
Furthermore, the Ni soap agent may have a structure represented by the following general formula (2) or (3).
Ni (-OOCCH (C _m H _{2m + 1} ) C _n H _{2n + 1} ) ₂ (2)
_{Ni (-OOCC p H 2p + 1} ) 2 ... (3)
(Where m, n and p are positive integers)
The metallization firing process is performed at a firing temperature of 250 ° C. or more and 400 ° C. or less in an inert gas atmosphere. The plating film is made of a Ni—P plating film, and the heat treatment of the plating film is performed at 250 ° C. or more and 300 ° C. It is preferable to perform a heat treatment for 1 hour or more at the following temperature, and palladium chloride can be used in the Pd catalyst treatment step.

The magnetic recording medium substrate of the present invention thus manufactured includes a glass substrate as a nonmagnetic substrate, a Ni adhesion layer on the glass substrate, a Pd catalyst layer on the Ni adhesion layer, and a Pd catalyst layer. A Ni-P plating layer, and the Ni-P plating layer has a film thickness of 1.0 μm or more and a surface roughness Ra of 0.5 nm or less on the surface of the Ni-P plating layer. The waviness Wa can be 0.5 nm or less.
The magnetic recording medium of the present invention comprises at least a magnetic recording layer on the magnetic recording medium substrate of the present invention, and the Ni—P plating layer of the magnetic recording medium substrate has a thickness of 1.0 wt% to 13. A soft magnetic to non-magnetic material made of a Ni—P alloy containing 0 wt% P can be used.

  According to the present invention, the Ni adhesion layer is interposed between the nonmagnetic substrate and the Pd catalyst layer, so that a plating layer having excellent adhesion can be electrolessly and uniformly deposited on the nonmagnetic substrate with a sufficient thickness. It can be formed by a plating method. Therefore, it is possible to provide a magnetic recording medium having good characteristics by using a glass substrate as the nonmagnetic substrate and forming a plating layer such as Ni-P on the surface thereof.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a process diagram showing an embodiment of a method for manufacturing a magnetic recording medium substrate according to the present invention, and FIG. 2 is a process diagram showing the details thereof. FIG. 3 is a schematic cross-sectional view showing an embodiment of a magnetic recording medium manufactured using the manufacturing method of this embodiment.
As shown in FIG. 3, a magnetic recording medium 100 according to an embodiment of the present invention includes a disk-shaped glass substrate 1 as a nonmagnetic substrate, a Ni adhesion layer 2 formed on the glass substrate 1, and a Ni adhesion layer 2. At least a magnetic recording layer 5 is provided on a magnetic recording medium substrate 10 including a Pd catalyst layer 3 formed thereon and a Ni—P plating layer 4 formed on the Pd catalyst layer 3.
As the nonmagnetic substrate, a silicon substrate, a carbon substrate, or the like can be used in addition to the glass substrate.

As shown in FIG. 1, the manufacturing method of the magnetic recording medium substrate 10 of such an embodiment uses a glass substrate 1 as a non-magnetic substrate, and a cleaning step S1 for cleaning the surface of the glass substrate 1; Ni adhesion layer forming step S2 for forming Ni adhesion layer 2 bonded to the surface of glass substrate 1, Pd catalyst layer forming step S3 for forming Pd catalyst layer 3 bonded to the surface of Ni adhesion layer 2, and Pd And a plating layer forming step S4 for forming the Ni-P plating layer 4 on the surface of the catalyst layer 3 as a catalyst by an electroless plating method.
Each of these steps S1 to S4 can be composed of the steps shown in FIG.
That is, the cleaning step S1 includes steps S11 and S12 for performing a degreasing process on the surface of the glass substrate 1, and a step S13 for performing an activation process on the surface of the glass substrate 1 subjected to the degreasing process.
The Ni adhesion layer forming step S2 includes steps S14 and S15 in which a Ni chelating agent or a Ni soap agent is applied to the surface of the glass substrate 1 that has been activated, and the applied Ni chelating agent or Ni soap agent is metallized and fired. The process includes steps S16 and S17 for forming a Ni metal film by processing, and step S18 for making the Ni metal film into the Ni adhesion layer 2 by performing an activation process on the surface of the Ni metal film.

The Pd catalyst layer forming step S3 includes a Pd catalyst forming step S19 in which Pd is bonded to the surface of the activated Ni metal film to form the Pd catalyst layer 3.
In the plating layer forming step S4, the surface of the Pd catalyst layer 3 as a catalyst is subjected to electroless Ni-P plating S20 to S22, and the plating film subjected to heat treatment after plating is subjected to Ni-P plating. It consists of process S23 made into layer 4.
A magnetic recording medium substrate 10 according to an embodiment of the present invention manufactured through such steps S1 to S4 is formed on a disk-shaped glass substrate 1 with a Ni adhesion layer 2 having a film thickness of 10 to 50 nm and a film thickness 1. The Pd catalyst layer 3 having a thickness of 10 nm and the Ni—P plating layer 4 having a thickness of 1 μm or more may be laminated.
A magnetic recording medium 100 according to an embodiment of the present invention is obtained by forming at least a magnetic recording layer 5 on a magnetic recording medium substrate 10 according to this embodiment.

The magnetic recording medium 100 can be manufactured by the following procedure.
That is, the surface of the Ni-P plating layer 4 of the above-described magnetic recording medium substrate 10 is subjected to necessary smoothing processing, texturing processing, and the like as necessary, and then the surface is made of non-metallic material such as Cr. A magnetic metal underlayer, a magnetic recording layer 5 of a ferromagnetic alloy thin film made of a Co alloy, a protective layer made of diamond-like carbon, etc. are sequentially formed by a sputtering method, and a perfluoropolyether is formed thereon as necessary. The magnetic recording medium 100 is manufactured by coating and forming a liquid lubricant layer composed of the above.
The magnetic recording medium 100 thus manufactured has a film thickness sufficient for a magnetic disk mounted on a hard disk device (film thickness of 1 μm to several μm), and sufficient adhesion, uniformity, and smoothness at the film thickness. Ni-P plating layer which can satisfy the properties can be provided and have good characteristics.

Below, each process of FIG. 2 is demonstrated in detail.
[Washing step S1 (S11 to S13)]
The surface of the glass substrate 1 is subjected to degreasing treatments S11 and S12 to remove and clean the organic film and particles.
After the cleaning, as an activation treatment S13 on the surface of the glass substrate 1, the inactive oxide film present on the surface of the glass substrate 1 is peeled and removed by immersion in a dilute aqueous acid solution, and at the same time, the functional groups on the surface of the glass substrate 1 Is converted to a silanol group (Si—OH) rich in reactivity, and the surface of the glass substrate 1 is activated.
[Ni adhesion layer forming step S2 (S14 to S18)]
Thus, the Ni chelating agent which becomes the adhesion layer material between the glass substrate 1 and the Ni—P plating layer 4 on the surface of the glass substrate 1 covered with silanol groups (Si—OH) whose surface is rich in reactivity. Alternatively, an appropriate amount of Ni soaping agent is applied S14 and S15.

As the Ni chelating agent which is the adhesion layer material, a structure represented by the following general formula (1) can be used.
Ni (C _i H _{2i + 1} COC _j H _2j COC _k H _{2k + 1} ) (1)
(Where i, j and k are positive integers)
Specifically, Ni chelating agents include, for example, “acetylacetonate Ni” represented by the following formula (4), “propionacetonate Ni” represented by formula (5), and formula (6): The “propion ethylate Ni” shown, and also hybrids thereof are preferred.
Ni (CH ₃ COCH ₂ COCH ₃ ) ₂ (4)
Ni (C ₂ H ₅ COCH ₂ COCH ₃ ) ₂ (5)
_{Ni (C 2 H 5 COCH 2} COC 2 H 5) 2 ... (6)
Moreover, the thing of the structure shown by the following general formula (2) or (3) can be used for Ni soap.

Ni (-OOCCH (C _m H _{2m + 1} ) C _n H _{2n + 1} ) ₂ (2)
_{Ni (-OOCC p H 2p + 1} ) 2 ... (3)
(Where m, n and p are positive integers)
Specifically, the Ni soap agent is preferably, for example, “2-ethylhexanoic acid Ni” represented by the following formula (7) or “Ni stearic acid Ni” represented by the formula (8).
_{Ni (-OOCCH (C 2 H 5} ) C 4 H 9) 2 ... (7)
Ni (-OOCC ₁₅ H ₃₁ ) ₂ (8)
Subsequently, in steps S16 and S17 of firing at an appropriate temperature in an inert gas atmosphere, the Ni chelating agent or Ni soaping agent is thermally transformed, the organic component is decomposed and volatilized, and Ni which is a metal component is the glass substrate 1. A Ni metal film in which Ni silanoxide (Si-ONi) is formed by dehydrogenation and substitution reaction with a silanol group that has been prepared in advance on the surface is obtained.

In the Ni metallization firing processes S16 and S17, the firing temperature of the Ni chelating agent is desirably 250 ° C. or higher and 350 ° C. or lower, and the firing temperature of the Ni soap agent is 300 ° C. or higher and 400 ° C. or lower for 30 minutes or longer. It is desirable.
Subsequently, as an activation process S18 of the Ni metal film, the Ni oxide film existing only on the outermost surface of several nm of the Ni metal film is removed by acid treatment.
[Pd catalyst layer forming step S3 (S19)]
Pd catalyzing treatment S19 is appropriately performed to form a Pd catalyst layer which becomes a catalyst layer for Ni-P plating deposition by bonding Pd to the surface of the Ni metal film from which the oxide film has been removed.
[Plating layer forming step S4 (S20 to S23)]
Electroless Ni-P plating is performed under predetermined conditions.

The plating solution for forming the Ni-P plating layer 4 is a so-called nonmagnetic high P concentration type Ni—P plating solution (P concentration of 11 to 13 wt%, for example, Nimden HDX manufactured by Uemura Kogyo Co., Ltd.). Medium P concentration type Ni-P plating solution (P concentration 6-8 wt%, for example Melplate NI-867 manufactured by Meltex Co., Ltd., P concentration 3-6 wt%, for example Melplate NI-802 manufactured by Meltex Corporation), and Is non-magnetic due to soft magnetism of soft magnetic low P concentration type Ni-P plating solution (P concentration of 1 to 2 wt%, for example, Nimden LPY manufactured by Uemura Kogyo Co., Ltd. or Top Nicolon LPH manufactured by Okuno Pharmaceutical Co., Ltd.) A Ni-P plating layer can be formed in all Ni-P plating solutions having a P concentration of 1 to 13 wt%.
In addition, the Ni—P plating layer can be formed even in a commercially available P concentration> 14 wt% further high P concentration type Ni—P plating solution that facilitates the plating deposition reaction.

Such nonmagnetic high P concentration Ni—P plating S20, nonmagnetic to soft magnetic medium P concentration Ni—P plating S21, and soft magnetic low P concentration Ni—P plating S22 are used, for example, in the following applications.
By forming a nonmagnetic high P concentration Ni-P plating film on a nonmagnetic glass substrate,
(1) Precise smoothing for high density, which is difficult with a high-rigidity glass substrate (2) Fabrication of anisotropic alignment medium using laser zone texture substrate or tape texture (3) Bias voltage is applied to the substrate during sputter deposition It is possible to increase the coercive force of the magnetic film by applying it.
Further, by forming a soft magnetic low P concentration Ni—P plating film on a nonmagnetic glass substrate, there is an application as a soft magnetic backing layer for a perpendicular magnetic recording medium. This perpendicular magnetic recording medium is provided with a soft magnetic film called a soft magnetic backing layer that is easy to pass a magnetic flux generated from a magnetic head and has a high saturation magnetic flux density under the magnetic recording layer that plays a role of recording information. A layer perpendicular magnetic recording medium that enables high-density recording.

The plating film composition as the soft magnetic backing layer for the perpendicular magnetic recording medium may be, for example, Co—Ni—Fe—P, Co—Ni—Fe—B, or other than the low P concentration Ni—P plating film described above. The same effect can be obtained even when an alloy is formed by combining some of these metals.
Further, by forming a non-magnetic to soft magnetic medium P-concentration Ni-P plating film on a non-magnetic glass substrate, in addition to the use of both the high P-concentration Ni-P plating film and the low P-concentration Ni-P plating film Furthermore, there is an application as a base plating film (strike plating) as an adhesion layer of a low P concentration Ni—P plating film to a nonmagnetic substrate.
Subsequently, by performing heat treatment (250 ° C., 4 hours) S23, the electroless Ni—P plating layer 4 having excellent adhesion can be formed uniformly and smoothly with a thickness of 1.0 μm or more. it can.

The heat treatment after the electroless Ni—P plating is desirably performed at a temperature of 250 ° C. or higher and 300 ° C. or lower for 1 hour or longer, and is preferably performed in an inert gas atmosphere.
As described above, the magnitude of the surface roughness Ra of the glass substrate 1 can act as a physical anchor effect on the adhesion of the Ni—P plating layer 4, but the adhesion of the Ni—P plating layer 4 is improved to some extent. The surface roughness Ra> 0.5 nm, which can be expected in the above, of course, even in the ultra-smooth glass substrate 1 with the surface roughness Ra <0.5 nm where the physical anchor effect can hardly be expected, The adhesion of the Ni-P plating layer 4 can be maintained.
That is, as described above, the glass is produced by generating dehydrogenated Ni silanoxide (Si-ONi) between the silanol group (Si—OH) on the surface of the glass substrate 1 and the Ni chelating agent or Ni soaping agent that is the material of the Ni adhesion layer 2. Due to the strong chemical bond between the glass substrate 1 and the Ni adhesion layer 2 at the interface of the substrate 1, an ultra-smooth glass substrate 1 in which physical adsorption force due to the anchor effect at a surface roughness Ra <0.5 nm can hardly be expected. In this case, sufficient adhesion of the Ni-P plating layer 4 can be maintained.

Furthermore, the Ni-P plating layer 4 formed on the glass substrate 1 obtained by this method is necessary for obtaining a magnetic disk having good characteristics in all Ni-P plating solutions showing non-magnetic to soft magnetism. Further, it can be formed with a sufficient film thickness (film thickness of 1 μm to 5 μm), and sufficient adhesion, uniformity, and smoothness can be satisfied in the film thickness region.
As described above, according to the embodiment of the present invention, the surface of the glass substrate 1 is subjected to the degreasing treatments S11 and S12 and the glass activation treatment S13, and the surface of the glass substrate 1 is coated with the Ni chelating agent or the Ni soap agent. S14, S15, Ni metallization firing treatments S16, S17, Ni metal film activation treatment S18 are performed to form the Ni adhesion layer 2, and Pd catalyst formation treatment S19 is performed on the Ni adhesion layer 2 to form the Pd catalyst layer 3 Since the electroless Ni—P plating S20 to S22 is performed on the Pd catalyst layer 3 and the heat treatment S23 is performed to form the Ni—P plating layer 4, Ni— having excellent adhesion is formed. The P plating layer can be formed uniformly and smoothly by an electroless plating method with a sufficient film thickness.

Below, the Example of this invention which actualized the above-mentioned embodiment is described based on FIG. 4, FIG. 5 with a comparative example. In addition, about the same part as the above-mentioned embodiment, the description is abbreviate | omitted and the same code | symbol is attached | subjected.
In FIG. 4, the various process conditions of each process process of an Example are shown. In FIG. 4, the processing items are processing step 30, processing liquid 31, concentration (wt%) 32, temperature (° C.) 33, processing time 34, and others 35. The processing steps (1) to (9) correspond to S11 to S23 in FIG.
[Example 1]
A chemically tempered glass plate is used as the glass substrate 1, and the surface thereof is subjected to the processing steps and processing conditions shown in (1) to (9) of FIG.
(1) Detergent degreasing: Detergent concentration 1.5 wt%, treatment at 50 ° C for 3 min
(2) Alkaline degreasing: KOH concentration 7.5 wt%, 50 ° C 3 min treatment
(3) Glass surface activation: HF + NH ₃ F concentration 1.0 wt%, treatment at 20 ° C. for 3 min
(4) Adhesion layer material Ni chelating agent coating: Acetylacetonate Ni / toluene solution dip coating acetylacetonate Ni concentration 0.3wt%
(5) Ni metal film calcination: calcination treatment at 300 ° C. for 1 hour in N ₂ gas atmosphere
(6) Ni metal film activation: HNO ₃ concentration 30 wt%, treatment at 20 ° C. for 2 min
(7) Pd catalyst layer formation: PdCl ₂ + NaOH concentration 3.0 wt%, treatment at 20 ° C. for 3 min
(8) Ni-P plating layer formation: plating solution “Nimden HDX (P concentration 15 to 20 wt%)” (manufactured by Uemura Kogyo Co., Ltd.), treatment at 80 ° C. for 20 min (Ni-P plating layer thickness 3.0 μm)
(9) Ni-P plating layer heating: Select a baking process at 250 ° C. for 4 hours in an N ₂ gas atmosphere, and in the processing steps and processing conditions of (1) to (9), FIG. The Ni-P plating layer 4 shown was formed.
[Example 2]
Among the processing steps and processing conditions shown in (1) to (9) of Example 1, the processing conditions of the processing step (8) are as follows:
(8) Ni-P plating layer formation: plating solution “Melplate NI-867 (P concentration 6-8 wt%)” (manufactured by Meltex Co., Ltd.), treated at 70 ° C. for 35 min (Ni-P plating layer thickness 3.0 μm) )
It was.

Other processing steps and processing conditions were the same as those in the processing steps (1) to (7) and (9) of Example 1, and the Ni—P plating layer 4 was formed by electroless plating.
Example 3
Among the processing steps and main conditions shown in (1) to (9) of Example 1, the processing conditions of the processing step (8) are as follows:
(8) Ni—P plating layer formation: plating solution “Nimden LPY (P concentration: 1-2 wt%)” (manufactured by Uemura Kogyo Co., Ltd.), treatment at 80 ° C. for 25 min (Ni—P plating layer thickness: 3.0 μm)
It was.
Other processing steps and processing conditions were the same as those in the processing steps (1) to (7) and (9) of Example 1, and the Ni—P plating layer 4 was formed by electroless plating.
Example 4
Among the processing steps and main conditions shown in (1) to (9) of Example 1, the processing conditions of the processing steps (4), (5) and (8) are as follows:
(4) Adhesion layer material Ni soap agent coating: 2-ethylhexanoic acid Ni concentration 0.3wt% dipping coating with 2-ethylhexanoic acid Ni / cyclohexane solution
(5) Ni metal film calcination: calcination treatment at 380 ° C. for 1 hour in N ₂ gas atmosphere
(8) Ni-P plating layer formation: plating solution “Nimden HDX (P concentration 11 to 13 wt%)” (manufactured by Uemura Kogyo Co., Ltd.), treatment at 80 ° C. for 20 min (Ni-P plating layer thickness 3.0 μm)
It was.

Other processing steps and processing conditions are the same as the processing steps (1) to (3), (6), (7) and (9) of Example 1, and the Ni-P plating layer 4 is formed by electroless plating. Filmed.
Example 5
Among the processing steps and main conditions shown in (1) to (9) of Example 1, the processing conditions of the processing steps (4), (5) and (8) are as follows:
(4) Adhesion layer material Ni soap agent coating: 2-ethylhexanoic acid Ni concentration 0.3wt% dipping coating with 2-ethylhexanoic acid Ni / cyclohexane solution
(5) Ni metal film calcination: calcination treatment at 380 ° C. for 1 hour in N ₂ gas atmosphere
(8) Ni-P plating layer formation: plating solution “Melplate NI-867 (P concentration 6-8 wt%)” (manufactured by Meltex Co., Ltd.), treated at 70 ° C. for 35 min (Ni-P plating layer thickness 3.0 μm) )
It was.

Other processing steps and processing conditions are the same as the processing steps (1) to (3), (6), (7) and (9) of Example 1, and the Ni-P plating layer 4 is formed by electroless plating. Filmed.
Example 6
Among the processing steps and main conditions shown in (1) to (9) of Example 1, the processing conditions of the processing steps (4), (5) and (8) are as follows:
(4) Adhesion layer material Ni soap agent coating: 2-ethylhexanoic acid Ni concentration 0.3wt% dipping coating with 2-ethylhexanoic acid Ni / cyclohexane solution
(5) Ni metal film calcination: calcination treatment at 380 ° C. for 1 hour in N ₂ gas atmosphere
(8) Formation of Ni—P plating layer 4: Plating solution “Nimden LPY (P concentration: 1 to 2 wt%)” (manufactured by Uemura Kogyo Co., Ltd.)), treatment at 80 ° C. for 25 min (Ni—P plating layer thickness: 3.0 μm) )
It was.

Other processing steps and processing conditions are the same as the processing steps (1) to (3), (6), (7) and (9) of Example 1, and the Ni-P plating layer 4 is formed by electroless plating. Filmed.
[Comparative example]
Next, a comparative example will be described.
[Comparative Example 1]
Using a chemically strengthened glass plate as the glass substrate 1,
(1) Detergent degreasing: Detergent concentration 1.5 wt%, treatment at 50 ° C for 3 min
(2) Alkaline degreasing: KOH concentration 7.5 wt%, 50 ° C 3 min treatment
(3) Glass surface roughening: Chromic acid + sulfuric acid concentration 40 wt% + 40 wt%, 60 ° C., 10 min treatment
(4) Catalyst imparting catalyst treatment: PdCl ₂ treated with 0.3 g / L + SnCl ₂ .2H ₂ O 15 g / L + 36% HCl in 200 ml / L mixed aqueous solution at 20 ° C. for 3 minutes
(5) Catalyst imparting accelerator treatment: H ₂ SO ₄ treated in 100 g / L aqueous solution at 50 ° C. for 5 min
(6) Ni—P plating layer formation: plating solution “Nimden HDX (P concentration 15 to 20%)” (manufactured by Uemura Kogyo Co., Ltd.), treatment at 80 ° C. for 3.0 min (the Ni—P plating layer thickness 0. (4μm and over 0.4μm cause film peeling during plating and cannot be formed)
(7) Heating of the Ni—P plating layer 4: A baking treatment was performed at 250 ° C. for 4 hours in an N ₂ gas atmosphere, and a Ni—P plating layer was formed by an electroless plating method.
[Comparative Example 2]
Among the processing steps and processing conditions shown in (1) to (7) of Comparative Example 1, the processing conditions of the processing step (6) are as follows:
(6) Ni-P plating layer formation: Plating solution “Melplate NI-867 (P concentration 6-8 wt%)” (manufactured by Meltex Co., Ltd.), treated at 80 ° C. for 9.0 min (film of Ni—P plating layer) (Thickness of 0.7μm and over 0.7μm will cause film peeling during plating and film formation is not possible)
It was.

Other processing steps and processing conditions were the same as those in the processing steps (1) to (5) and (7) of Comparative Example 1, and a Ni—P plating layer was formed by electroless plating.
[Comparative Example 3]
Among the processing steps and processing conditions shown in (1) to (7) of Comparative Example 1, the processing conditions of the processing step (6) are as follows:
(6) Ni—P plating layer formation: plating solution “Nimden LPY (P concentration 1 to 2 wt%)” (manufactured by Uemura Kogyo Co., Ltd.), treatment at 80 ° C. for 3.0 min (Ni—P plating layer thickness 0.5 μm) If over 0.5μm, film peeling occurs during plating, and film formation is not possible)
It was.
Other processing steps and processing conditions were the same as those in the processing steps (1) to (5) and (7) of Comparative Example 1, and a Ni—P plating layer was formed by electroless plating.
[Evaluation]
In FIG. 5, the evaluation result of the said Examples 1-6 and Comparative Examples 1-3 is shown. In FIG. 5, evaluation items were an adhesion layer 40, a plating layer 41, a plating film thickness 42, an adhesion force 43, and a surface roughness (Ra) 44. In the figure, ◯ indicates good adhesion, and x indicates poor adhesion.

Specifically, for each glass substrate on which the electroless plating of the Ni-P plating layer was performed, the adhesion of the Ni-P plating layer was evaluated by a cross-cut peel test (JIS K 5400 6.15).
In addition, by measuring the surface roughness with an atomic force microscope (AFM), the average roughness Ra after plating was evaluated for a glass substrate 1 having a surface average roughness Ra of 0.25 nm before plating.
As can be seen from FIG. 5, the Ni—P plating layer 4 on the glass substrate 1 obtained in Examples 1 to 6 manufactured in the processing steps and processing conditions of FIG. 4 has a thickness of 3.0 μm. It can be seen that the Ni—P plating layer in the low P to high P concentration region is formed with excellent adhesion.
Moreover, the surface roughness Ra after plating was 0.5 nm or less, and the minute surface waviness Wa was 0.5 nm or less. As a result, the change in surface roughness is slight, and the surface roughness level required for the magnetic disk can be sufficiently maintained.

On the other hand, the Ni-P plating layer on the glass substrate obtained in Comparative Examples 1 to 3, which is publicly known, has a plating film thickness of 0.4 to 0.7 μm and cannot be thickened by 1.0 μm or more. And it turns out that the adhesiveness with respect to a glass substrate is also falling remarkably.
As described above, degreasing treatments S11 and S12 and glass activation treatment S13 are performed on the surface of the glass substrate 1, and Ni chelating agent or Ni soaping agent coating treatments S14 and S15 and Ni metal are applied to the surface of the glass substrate 1. The Ni adhesion layer 2 is formed by applying the calcination treatments S16 and S17 and the Ni metal film activation process S18, and the Pd catalyst layer 3 is formed on the surface of the Ni adhesion layer 2 by applying the Pd catalyst formation treatment S19. Since the electroless Ni—P plating S20 to S22 having a P concentration of 1 to 13 wt% is performed on the Pd catalyst layer 3 and the heat treatment S23 is performed, the Ni—P plating layer 4 is formed. The Ni—P plating layer 4 having excellent properties can be formed uniformly and smoothly by an electroless plating method with a thick film of 1.0 μm or more. Therefore, a magnetic disk having good characteristics can be manufactured using the glass substrate on which the Ni-P plating layer 4 is formed.

It is process drawing which shows embodiment of the manufacturing method of the board | substrate for magnetic recording media based on this invention. It is process drawing which shows the detail of each process of embodiment of FIG. It is a schematic cross section of the magnetic recording medium manufactured using the manufacturing method of embodiment of this invention. It is explanatory drawing which shows the various process conditions of each process process of the Example of this invention. It is explanatory drawing which shows the evaluation result of the Example and comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Ni adhesion layer 3 Pd catalyst layer 4 Ni-P plating layer 5 Magnetic recording layer 10 Magnetic recording medium substrate 100 Magnetic recording medium S1 Cleaning step S2 Ni adhesion layer formation step S3 Pd catalyst layer formation step S4 Plating layer formation Process

Claims (10)

In the method for manufacturing a magnetic recording medium substrate in which a plating layer is formed on a nonmagnetic substrate,
A cleaning step of cleaning the surface of the non-magnetic substrate;
A Ni adhesion layer forming step of forming a Ni adhesion layer bonded to the surface of the non-magnetic substrate after the cleaning;
A Pd catalyst layer forming step of forming a Pd catalyst layer bonded to the surface of the Ni adhesion layer;
And a plating layer forming step of forming the plating layer on the surface of the Pd catalyst layer as a catalyst by an electroless plating method. The non-magnetic substrate is a glass substrate,
The cleaning step includes a step of performing a degreasing process on the surface of the glass substrate, and a step of performing an activation process on the surface of the glass substrate subjected to the degreasing process,
The Ni adhesion layer forming step includes a step of applying a Ni chelating agent or a Ni soap agent to the surface of the glass substrate subjected to the activation treatment, and a metallization baking treatment of the applied Ni chelating agent or Ni soap agent. Forming a Ni metal film and a process of making the Ni metal film the Ni adhesion layer by applying an activation treatment to the surface of the Ni metal film,
The Pd catalyst layer forming step comprises a Pd catalyst forming step of forming Pd catalyst layer by bonding Pd to the surface of the Ni metal film subjected to the activation treatment,
The plating layer forming step includes a step of forming a plating film on the surface of the Pd catalyst layer as a catalyst by an electroless plating method, and a step of heating the plating film to form the plating layer. The method for manufacturing a substrate for a magnetic recording medium according to claim 1. The method for producing a substrate for a magnetic recording medium according to claim 2, wherein the Ni chelating agent has a structure represented by the following general formula (1).
Ni (C _i H _{2i + 1} COC _j H _2j COC _k H _{2k + 1} ) (1)
(Where i, j and k are positive integers) The method for manufacturing a substrate for a magnetic recording medium according to claim 2, wherein the Ni soap agent has a structure represented by the following general formula (2) or (3).
Ni (-OOCCH (C _m H _{2m + 1} ) C _n H _{2n + 1} ) ₂ (2)
_{Ni (-OOCC p H 2p + 1} ) 2 ... (3)
(Where m, n and p are positive integers)   5. The method for manufacturing a substrate for a magnetic recording medium according to claim 2, wherein the metallized baking treatment is performed at a baking temperature of 250 ° C. or higher and 400 ° C. or lower in an inert gas atmosphere. .   6. The method of manufacturing a substrate for a magnetic recording medium according to claim 2, wherein palladium chloride is used in the Pd catalyzing treatment step.   7. The plating film according to claim 2, wherein the plating film is a Ni-P plating film, and the heat treatment of the plating film is performed at a temperature of 250 ° C. or higher and 300 ° C. or lower for 1 hour or longer. A method for producing a magnetic recording medium substrate according to claim 1. In a magnetic recording medium substrate comprising a Ni-P plating layer on a glass substrate,
A Ni adhesion layer formed on the glass substrate;
A Pd catalyst layer formed on the Ni adhesion layer;
The Ni-P plating layer formed on the Pd catalyst layer,
The Ni—P plating layer has a film thickness of 1.0 μm or more, and has a surface roughness Ra of 0.5 nm or less and a minute surface waviness Wa of 0.5 nm or less on the surface of the Ni—P plating layer. A substrate for a magnetic recording medium, characterized in that   A magnetic recording medium comprising at least a magnetic recording layer on the magnetic recording medium substrate according to claim 8.   The magnetic recording medium according to claim 9, wherein the Ni—P plating layer of the magnetic recording medium substrate is made of a Ni—P alloy containing 1.0 wt% to 13.0 wt% of P.

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