WO2011034008A1

WO2011034008A1 - Microstructure and method for producing same

Info

Publication number: WO2011034008A1
Application number: PCT/JP2010/065633
Authority: WO
Inventors: 義治田川; 優介畠中
Original assignee: 富士フイルム株式会社
Priority date: 2009-09-16
Filing date: 2010-09-10
Publication date: 2011-03-24
Also published as: JP2011084810A

Abstract

Disclosed is a microstructure comprising an anodized film of aluminum or an aluminum alloy, wherein the degree of regularization of a plurality of micropores on the bottom surface is 70% or more, the center-to-center distance between the micropores is 600 nm or more, and the length of each micropore in the axial direction is 50 μm or more. Also disclosed is a method for producing the microstructure.

Description

Fine structure and manufacturing method thereof

The present invention relates to a microstructure, and more particularly to a microstructure having a long-period micropore array and a method for manufacturing the same.

In the technical fields of metal and semiconductor thin films, thin wires, dots, etc., the phenomenon of electrical, optical and chemical peculiarities is seen by confining the movement of free electrons in a size smaller than a certain characteristic length. Yes. Such a phenomenon is called “quantum mechanical size effect (quantum size effect)”. Research and development of functional materials applying such a unique phenomenon is actively underway. Specifically, a material having a structure finer than several hundred nm is called a “microstructure” or “nanostructure”, and is a target for material development.

Examples of such a fine structure manufacturing method include a method of directly manufacturing a nano structure by a semiconductor processing technique including a fine pattern forming technique such as photolithography, electron beam exposure, and X-ray exposure.

In particular, much research has been conducted on a method for manufacturing a microstructure having a regular micropore.
For example, as a method of forming a regular structure in a self-regulating manner, an anodized alumina film (anodized film) obtained by anodizing aluminum in an electrolytic solution can be mentioned. It is known that a plurality of fine pores (micropores) having a diameter of about several nm to several hundred nm are regularly formed in the anodized film. By using this self-ordering of the anodized film and obtaining a perfectly regular arrangement, theoretically, hexagonal prism cells with a regular hexagonal bottom centered around the micropores are formed, and adjacent micropores are formed. It is known that the connecting line forms an equilateral triangle.

As examples of applications of such an anodized film having micropores, optical functional nanodevices, magnetic devices, luminescent carriers, catalyst carriers and the like are known. For example, Patent Document 1 describes that pores are sealed with metal to generate local plasmon resonance and applied to a Raman optical analyzer.
There is known a method in which a depression that is a starting point for generating micropores in an anodizing process is formed before the anodizing process for forming micropores. By forming the depressions in this way, it becomes easy to control the variation in the arrangement of micropores and the pore diameter within a desired range.
As a general method for forming the depression, a self-ordering method using the self-ordering property of the anodized film is known. This is a method for improving the regularity by utilizing the property that the micropores of the anodized film are regularly arranged and removing the factors that disturb the regular arrangement.

Patent Document 2 discloses that anodization is performed with an anodic oxidation voltage obtained by gradually reducing the interval (period) of the recesses of the micropores at 2.5 nm / V, that is, the pore period can be adjusted by a voltage value. Is described. However, there is no description of an anodic oxide film having a pore period exceeding 500 nm.

JP 2007-231336 A Japanese Patent No. 3714507

In the self-ordering method described in Patent Document 1, when the average pore density is 15 pieces / μm ² or less, that is, when the distance between the center of gravity of the micropores is 300 nm or more, the film growth rate of the anodized film is set to a speed necessary for the honeycomb arrangement. It was difficult to maintain the structure of the ordered micropores, and it was difficult to grow the film in the axial direction of the micropores.

As a result of earnest research to achieve the above-mentioned object, the present inventor performs anodizing treatment using an electrolytic solution containing a specific carboxylic acid, so that the honeycomb arrangement of the micropores arranged in the honeycomb is not destroyed. The inventors have found that a fine structure having a large distance between centers of micropores and a film thickness of 50 μm or more can be produced, and the present invention has been completed.

That is, the present invention provides the following (1) to (4).
(1) A microstructure comprising an anodized film of aluminum or an aluminum alloy, wherein the degree of ordering of the plurality of micropores defined by the following general formula (1) is 70% or more on the bottom surface, A fine structure having a center-to-center distance of 600 nm or more and an axial length of the micropore of 50 μm or more:
General formula (1)
Ordering degree (%) = B / A × 100
In the general formula (1), A represents the total number of micropores in the measurement range. B, when a circle with the shortest radius inscribed in the edge of the other micropore is drawn from the center of the cross section perpendicular to the major axis of one micropore, the micropores other than the micropore are inside the circle. This represents the number in the measurement range of the one micropore that will contain six pore centers.
(2) The microstructure according to claim 1, wherein a distance between centers of micropores of the microstructure is 600 nm to 1200 nm.
Here, the distance (period) between the centers of the micropores means the distance between the center of the cross section perpendicular to the major axis of one annular micropore and the center of the next nearest micropore. When the shape of the cross section perpendicular to the major axis of the pore is not a perfect circle, it means the center of gravity of the cross section in the perpendicular direction. The distance (cycle) between the centers means an average value of a plurality of micropores unless otherwise specified. Similarly, the length, density, and the like of the micropores in the axial direction are average values of a plurality of micropores unless otherwise specified.
The bottom surface is the surface of the fine structure perpendicular to the axis of the annular micropore, and has a plurality of holes in the micropore, and when the fine structure is manufactured from aluminum or an aluminum alloy plate, It is a plane close to the aluminum alloy plate and refers to the surface obtained by removing the aluminum or aluminum alloy plate.
(3) Anodizing the aluminum or aluminum alloy plate by applying a voltage of 195 V or more in an acidic aqueous solution containing an aliphatic carboxylic acid having 3 or more carbon atoms or an aromatic carboxylic acid (1) or ( The manufacturing method of the microstructure described in 2).
(4) The carboxylic acid is at least one selected from the group consisting of malonic acid, succinic acid, adipic acid, tartaric acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, and terephthalic acid ( The manufacturing method of the fine structure as described in 3).

When the micropore is filled with a conductive material, the microstructure has conductivity in the micropore penetrating direction (axial direction of the annular micropore) and has insulation on a surface perpendicular to the micropore penetrating direction. It can be used as an anisotropic conductive film. In addition, it is expected to be used as a precision filter using the uniformity of micropore diameter, the finely packed structure of micropores, and the straight pipe structure.

The present invention provides a microstructure in which the degree of ordering defined by the general formula (1) is 70% or more, the distance between the centers of the micropores is 600 nm or more, and the thickness of the micropores is 50 μm or more. The body can be provided. Moreover, the manufacturing method of this invention can manufacture the microstructure of this invention.

FIGS. 1A and 1B are simplified views showing an example of a preferred embodiment of the anisotropic conductive member of the present invention. FIG. 1A is a front view, and FIG. FIG. 6 is a cross-sectional view taken along section line IB-IB in FIG. 2A and 2B are explanatory diagrams of a method for calculating the degree of ordering of pores. 3A to 3D are schematic end views for explaining an example of anodizing treatment in the production method of the present invention.

The present invention is described in detail below.
<Microstructure>
The microstructure of the present invention comprises an anodized film of aluminum or an aluminum alloy having micropores.
The microstructure of the present invention will be described with reference to FIG. The microstructure has a plurality of micropores. In the present specification, unless otherwise specified, the definition of micropores is indicated by an average value of 25 or more micropores.

1A and 1B are simplified views showing an example of a preferred embodiment of the microstructure of the present invention. FIG. 1A is a front view, and FIG. 1B is a cross-sectional line IB- in FIG. It is sectional drawing seen from IB.
The microstructure 1 of the present invention is composed of an oxide film 2 and micropores 3.
As shown in FIG. 1B, the micropore 3 is an annular hole, and is preferably provided so as to be substantially parallel to the thickness direction of the oxide film 2 (parallel in FIG. 1).
The distance between the centers of the micropores 3 of the microstructure 1 of the present invention (portion represented by reference numeral 9 in FIGS. 1A and 1B) is 600 nm or more. Preferably, it is 600 to 1200 nm, more preferably 600 to 1000 nm, and even more preferably more than 600 nm to 1000 nm.
Within this range, when used as an anisotropic conductive film, the balance between insulation and conductivity is good.
In the present invention, the thickness of the oxide film (the portion represented by reference numeral 6 in FIG. 1B), which is the axial length of the annular micropore, is 50 μm or more. The thickness is preferably 50 to 200 μm, more preferably 50 to 150 μm, and even more preferably 50 to 100 μm.
Within this range, when used for various purposes, the mechanical strength is high and handling is easy.
The micropore density is preferably 3.55 / μm ² or less, 0.10 / μm ² or more, more preferably 3.55 / μm ² or less, 0.50 / μm ² or more, and further 3. The number is preferably 53 / μm ² or less and 0.81 / μm ² or more. Within this range, a microstructure having a sufficiently large distance between the centers of the micropores can be obtained.

The oxide film 2 constituting the microstructure of the present invention is an oxide film of aluminum or an aluminum alloy plate, and is formed by an anodic oxidation treatment.
In the present invention, the diameter of the micropore (portion represented by reference numeral 8 in FIG. 1B) is preferably 10 to 590 nm, and more preferably 150 to 360 nm. This is because the micropore diameter at the time of the formation of the anodizing treatment is excellent in uniformity, which is preferable.

In the present invention, the microstructure 1 has a bottom surface of a plurality of micropores defined by the following general formula (1) having a degree of ordering of 70% or more. The bottom surface is the surface of the fine structure perpendicular to the axis of the annular micropore. When the fine structure is manufactured from an aluminum or aluminum alloy plate, the aluminum or aluminum alloy plate has a plurality of micropores. The surface of the oxide film obtained after the aluminum or aluminum alloy plate is removed if the aluminum or aluminum alloy plate is removed. In FIG. 1B, the plane 4 on the side represented by the symbol Z2 is meant. The other of the bottom surface 4 of the microstructure 1 is a surface 5, which is a plane on the side represented by reference sign Z <b> 1 in FIG.
The measurement of the degree of ordering of the micropores on the bottom surface is carried out in a method for producing a microstructure according to the present invention, which will be described later, by performing film dissolution after anodizing treatment, and using a predetermined image from an image obtained by observing the bottom surface with a scanning electron microscope. The number of micropores is visually confirmed and calculated from the following general formula (1). Further, the shape which becomes the starting point of the final anodizing treatment may be observed in the same manner.

Ordering degree (%) = B / A × 100 (1)
In the general formula (1), A represents the total number of micropores in the measurement range. B, when a circle with the shortest radius inscribed in the edge of the other micropore is drawn from the center of the cross section perpendicular to the major axis of one micropore, the micropores other than the micropore are inside the circle. This represents the number in the measurement range of the one micropore that will contain six pore centers.

FIG. 2 is an explanatory diagram of a method for calculating the degree of ordering of micropores. The above formula (1) will be described more specifically with reference to FIG.
The micropore 101 shown in FIG. 2A is centered on the center of gravity of the micropore 101 and has the shortest radius 103 inscribed in the edge of another micropore (in the figure, inscribed in the micropore 102). ) Includes six micropore centers other than the micropore 101 inside the circle 103. Therefore, the micropore 101 is included in B.
The micropore 104 shown in FIG. 2B is centered on the center of gravity of the micropore 104 and has the shortest radius 106 inscribed in the edge of another micropore (in the figure, inscribed in the micropore 105). ) Includes five centroids of micropores other than the micropores 104 inside the circle 106. Therefore, the micropore 104 is not included in B.
Further, the micropore 107 shown in FIG. 2B is centered on the center of gravity of the micropore 107 and has the shortest radius 109 inscribed in the edge of another micropore (inscribed in the micropore 108). Is drawn, the circle 109 includes seven centroids of micropores other than the micropore 107. Therefore, the micropore 107 is not included in B.

The above-mentioned fine structure is expected to be used as an anisotropic conductive film by filling a micropore with metal by electrolytic plating or electroless plating. Further, by immersing the fine structure in an alkaline solution, the micropore bottom surface is penetrated, and the use as a precision filter is expected.

For example, the microstructure of the present invention is anodized by applying a voltage of 195 V or more in an acidic aqueous solution containing an aliphatic carboxylic acid having 3 or more carbon atoms or an aromatic carboxylic acid to an aluminum or aluminum alloy plate. It can be manufactured by processing.

FIG. 3 is a schematic cross-sectional view of an aluminum member and a microstructure for explaining the manufacturing method of the microstructure of the present invention.

<Aluminum substrate>
The aluminum or aluminum alloy substrate is not particularly limited. For example, a pure aluminum plate; an alloy plate containing aluminum as a main component and containing a small amount of foreign elements; a substrate obtained by depositing high-purity aluminum on low-purity aluminum (for example, recycled material) A substrate in which high purity aluminum is coated on the surface of a silicon wafer, quartz, glass or the like by a method such as vapor deposition or sputtering; a resin substrate in which aluminum is laminated.

Of the aluminum substrate, the surface on which the anodized film is provided by anodization treatment has an aluminum purity of preferably 99.5% by mass or more, more preferably 99.9% by mass or more, and 99.99% by mass. % Is more preferable. When the aluminum purity is in the above range, the regularity of the micropore array is sufficient.

The surface of the aluminum substrate is preferably preliminarily degreased and mirror-finished.

<Mirror finish processing>
The mirror finishing process is performed to eliminate unevenness on the surface of the aluminum substrate and improve the uniformity and reproducibility of the particle forming process by an electrodeposition method or the like. As an unevenness | corrugation of the surface of an aluminum member, the rolling rebar generated at the time of rolling in the case where an aluminum member is manufactured through rolling is mentioned, for example.
In the present invention, the mirror finish processing is not particularly limited, and a conventionally known method can be used. Examples thereof include mechanical polishing, chemical polishing, and electrolytic polishing.
Examples of the mechanical polishing include a method of polishing with various commercially available polishing cloths, and a method of combining various commercially available abrasives (for example, diamond, alumina) and a buff. Specifically, a method using an abrasive and a method of changing the used abrasive from coarse particles to fine particles over time are preferably exemplified. In this case, the final polishing agent is preferably # 1500. Thus, the glossiness can be 50% or more (in the case of rolled aluminum, both the rolling direction and the width direction are 50% or more).

Examples of chemical polishing include various methods described in “Aluminum Handbook”, 6th edition, edited by Japan Aluminum Association, 2001, p.164-165.
Further, the phosphoric acid-nitric acid method, Alupol I method, Alupol V method, Alcoa R5 method, H ₃ PO ₄ —CH ₃ COOH—Cu method, and H ₃ PO ₄ —HNO ₃ —CH ₃ COOH method are preferably mentioned. Of these, the phosphoric acid-nitric acid method, the H ₃ PO ₄ —CH ₃ COOH—Cu method, and the H ₃ PO ₄ —HNO ₃ —CH ₃ COOH method are preferable.
By chemical polishing, the glossiness can be set to 70% or more (in the case of rolling, 70% or more in both the rolling direction and the width direction).

Examples of the electrolytic polishing include various methods described in “Aluminum Handbook”, 6th edition, edited by Japan Aluminum Association, 2001, p.164-165.
Further, a method described in US Pat. No. 2,708,655 is preferably exemplified.
"Practical surface technology", vol. 33, No. 3, 1986, p32-38 is also preferred.
By electropolishing, the gloss can be 70% or more (in the case of rolled aluminum, both the rolling direction and the width direction are 70% or more).

These methods can be used in appropriate combination. For example, a method of using an abrasive is preferably performed by changing the abrasive to be used from coarse particles to fine particles over time, and then performing electrolytic polishing.

By mirror finishing, for example, a surface having an average surface roughness Ra, 0.1 μm or less, and a glossiness of 50% or more can be obtained. The average surface roughness is preferably 0.03 μm or less, and more preferably 0.02 μm or less. Further, the glossiness is preferably 70% or more, and more preferably 80% or more.
The glossiness is a regular reflectance obtained in accordance with JIS Z8741-1997 “Method 3 60 ° Specular Gloss” in the direction perpendicular to the rolling direction. Specifically, using a variable angle gloss meter (for example, VG-1D, manufactured by Nippon Denshoku Industries Co., Ltd.), when the regular reflectance is 70% or less, the incident reflection angle is 60 degrees and the regular reflectance is 70%. In the case of exceeding, the incident / reflection angle is 20 degrees.

<Degreasing treatment>
Degreasing treatment uses acids, alkalis, organic solvents, etc. to dissolve and remove the organic components such as dust, fat, and resin that adhere to the aluminum surface, and removes defects in each treatment described below caused by the organic components. It is performed for the purpose of preventing the occurrence. Further, it is also used for the purpose of removing the oxide film formed on the film during the mirror finishing process.
A conventionally known degreasing agent can be used for the degreasing treatment. Specifically, for example, various commercially available degreasing agents can be used by a predetermined method.

Especially, the following each method is illustrated suitably.
A method of bringing an organic solvent such as alcohol (for example, methanol), ketone, benzine, or volatile oil into contact with the aluminum surface at room temperature (organic solvent method); contacting an organic solvent such as acetone with the aluminum surface at room temperature and using ultrasonic waves Method (ultrasonic cleaning method); Method of bringing a solution containing a surfactant such as soap and neutral detergent into contact with the aluminum surface at a temperature from room temperature to 80 ° C., and then washing with water (surfactant method); concentration A method in which a 10 to 200 g / L sulfuric acid aqueous solution is brought into contact with an aluminum surface at a temperature from room temperature to 70 ° C. for 30 to 80 seconds and then washed with water; a sodium hydroxide aqueous solution having a concentration of 5 to 20 g / L is applied to the aluminum surface at a normal temperature. while contacting about seconds, the aluminum surface is electrolyzed by applying a direct current of a current density of 1 ~ 10A / dm ² in the cathode, then the concentration 100 ~ 500 g / L How neutralized by contacting the aqueous solution of nitric acid; while various known anodizing electrolytic solution is brought into contact with the aluminum surface at ordinary temperature, by passing a direct current of a current density of 1 ~ 10A / dm ² of the aluminum surface in the cathode Alternatively, a method in which an alternating current is applied for electrolysis; an alkaline aqueous solution having a concentration of 10 to 200 g / L is brought into contact with an aluminum surface at 40 to 50 ° C. for 15 to 60 seconds, and then an aqueous nitric acid solution having a concentration of 100 to 500 g / L is contacted. Neutralization method: A method in which an emulsion prepared by mixing a surfactant, water, etc. with light oil, kerosene, etc. is brought into contact with the aluminum surface at a temperature from room temperature to 50 ° C. for 30 to 180 seconds and then washed with water (emulsification and degreasing) Method): A method in which a mixed solution of sodium carbonate, phosphates, surfactant, etc. is brought into contact with the aluminum surface at a temperature from room temperature to 50 ° C. for 30 to 180 seconds and then washed with water. Phosphate method) can be exemplified.

<Micropore starting point formation method>
As a method for forming the starting point of the micropore, a conventionally known method can be used. Specifically, it is preferable to use the self-ordering method described later.
The self-ordering method is a method of improving the regularity by utilizing the property that the micropores of the anodized film are regularly arranged and removing the factors that disturb the regular arrangement. Specifically, high-purity aluminum is used, and an anodized film is formed at a voltage corresponding to the type of the electrolyte.
In this method, since the micropore diameter depends on the voltage, a desired micropore diameter can be obtained to some extent by controlling the voltage.

The average flow rate during the anodizing treatment is preferably 0.5 to 20.0 m / min, more preferably 1.0 to 15.0 m / min, and 2.0 to 10.0 m / min. More preferably, it is min. By performing anodization at a flow rate in the above range, uniform and high regularity can be obtained.
Moreover, the method of flowing the electrolytic solution under the above conditions is not particularly limited, but for example, a method using a general stirring device such as a stirrer is used. It is preferable to use a stirrer capable of controlling the stirring speed by digital display because the average flow rate can be controlled. Examples of such a stirring device include a magnetic stirrer HS-50D manufactured by AS ONE.

The anodizing treatment is performed by applying a voltage of 195 V or more in an acidic aqueous solution containing an aliphatic carboxylic acid having 3 or more carbon atoms or an aromatic carboxylic acid. The voltage used for the anodizing treatment can be 195 to 600V, preferably 195V to 500V, and more preferably 195V to 400V.
The average micropore density corresponding to the processing voltage is 0.57 to 3.53 / μm ² .
The generated current density during the anodizing treatment can be used at 1000 A / m ² or less, preferably 500 A / m ² or less, more preferably 400 to 100 A / m ² , and even more preferably 250 A / m ² .
As long as it is within the above voltage / current density range, either constant voltage processing or constant current processing can be performed.

The electrolytic solution used for the anodizing treatment is an acidic aqueous solution containing an aliphatic carboxylic acid having 3 or more carbon atoms or an aromatic carboxylic acid. For the aliphatic carboxylic acid, propionic acid, butyric acid, valeric acid, Caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexaenoic acid, eicosapentanoic acid, malonic acid, Succinic acid, adipic acid, tartaric acid, malic acid, and citric acid can be used, malonic acid, succinic acid, adipic acid, and tartaric acid are preferable, and malonic acid, succinic acid, and tartaric acid are more preferable.
As for aromatic carboxylic acids, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, hemimellitic acid, trimellitic acid, trimesic acid, melophanoic acid, planitic acid, pyromellitic acid, mellitic acid, diphenic acid, toluic acid, Xylyl acid, hemelic acid, mesitylene acid, prenicylic acid, jurylic acid, cumic acid are preferable, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid can be used, and benzoic acid, phthalic acid, isophthalic acid, terephthalic acid are preferable. More preferred are phthalic acid, isophthalic acid, and terephthalic acid.
Said carboxylic acid may be used independently and may be used in mixture of 2 or more types.
Acids other than the above carboxylic acids may be used as long as the effects of the present invention are not impaired, but the total acid concentration in the aqueous solution is 50% by mass or less. For acids other than the above carboxylic acids, sulfuric acid, phosphoric acid, boric acid and the like may be used together with the above carboxylic acids.

The concentration of the carboxylic acid can be 0.01 mol / L to 10 mol / L, preferably 0.05 to 5 mol / L, and more preferably 0.1 to 5.0 mol / L.
The electrolyte temperature used for the anodizing treatment can be 0-100 ° C., preferably 0-50 ° C., more preferably 0-20 ° C.

The micropore density is preferably 3.55 / μm ² or less, 0.10 / μm ² or more, more preferably 3.55 / μm ² or less, 0.50 / μm ² or more, and further 3. The number is preferably 53 / μm ² or less and 0.81 / μm ² or more.

<Regularization processing>
The ordering process is a process in which a process consisting of a film dissolving process for dissolving the anodized film and an anodizing process after the film dissolving process is performed once or more.

<Film dissolution treatment>
The film dissolution treatment is a treatment for dissolving the anodized film of the aluminum member described above. Thereby, a part of the irregular arrangement on the surface of the anodized film is partially dissolved, so that the regularity of the arrangement of the micropores becomes high. In addition, by dissolving the film, the current density rises during the first anodic oxidation after the film is dissolved, and as a result, the regularity of the arrangement of micropores increases.

The film dissolution treatment is performed by bringing the aluminum member into contact with an acidic aqueous solution or an alkaline aqueous solution. The method of making it contact is not specifically limited, For example, the immersion method and the spray method are mentioned. Of these, the dipping method is preferred.

When an aqueous acid solution is used for the film dissolution treatment, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, or a mixture thereof. Especially, the aqueous solution which does not contain chromic acid is preferable at the point which is excellent in safety | security. The concentration of the acid aqueous solution is preferably 1 to 10% by mass. The temperature of the aqueous acid solution is preferably 25 to 40 ° C.
When an alkaline aqueous solution is used for the film dissolution treatment, it is preferable to use an aqueous solution of at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The temperature of the alkaline aqueous solution is preferably 20 to 35 ° C.
Specifically, for example, 50 g / L, 40 ° C. phosphoric acid aqueous solution, 0.5 g / L, 30 ° C. sodium hydroxide aqueous solution or 0.5 g / L, 30 ° C. potassium hydroxide aqueous solution is preferably used. .
The immersion time in the acid aqueous solution or alkali aqueous solution is preferably 8 to 60 minutes, more preferably 10 to 50 minutes, and further preferably 15 to 30 minutes.

<Anodizing treatment>
The anodizing treatment is performed after the above-described film dissolution treatment. Thereby, the oxidation reaction of the aluminum substrate proceeds, and the anodic oxide film dissolved by the film dissolution treatment becomes thick.

The anodizing treatment may be performed by a conventionally known method, but is preferably performed under the same conditions as the method of the present invention used in the self-ordering method described above.

In the anodizing treatment, the electrolysis time is preferably 1 to 100 hours, more preferably 30 to 80 hours, and further preferably 40 to 50 hours.

In the ordering treatment, the above-described film dissolution treatment and the subsequent anodic oxidation treatment may be performed once or more. The larger the number of repetitions, the higher the regularity of the micropore arrangement described above. Therefore, this step may be repeated two or more times, three or more times, or four or more times.
In the regularization treatment, when the above steps are repeated twice or more, the conditions of each film dissolution treatment and anodization treatment may be the same or different.

For example, FIG. 3A shows an aluminum substrate 12a and an anodized film 14a having micropores 16a present on the surface of the aluminum substrate 12a. Next, in FIG. 3B, the surface of the anodized film 14a shown in FIG. 3A and the inside of the micropores 16a are dissolved by the first film dissolution treatment, and the micropores 16a are formed on the aluminum substrate 12a. An anodized film 14b having a pore 16b is formed, and the anodized film 14b remains on the bottom surface of the micropore 16b. In FIG. 3C, the oxidation reaction of the aluminum substrate 12a shown in FIG. 3B proceeds by the next anodic oxidation treatment, and the micropores 16c deeper than the micropores 16b are formed on the aluminum substrate 12b. An anodic oxide film 14c that is thicker than the anodic oxide film 14b is obtained. In FIG. 3D, the surface of the anodic oxide film 14c shown in FIG. 3C and the inside of the micropore 16c are dissolved by the second film dissolution treatment, and the micropore 16d is formed on the aluminum substrate 12b. The microstructure 20 having the anodic oxide film 14d is obtained. The barrier layer is indicated by 18d. Although the anodic oxide film 14d remains in FIG. 3D, the anodic oxide film may be completely dissolved in the second film dissolution treatment. When all of the anodized film is dissolved, the depressions present on the surface of the aluminum substrate become micropores of the fine structure.

The fine structure of the present invention is obtained by the manufacturing method described above. Moreover, the aluminum or aluminum alloy substrate of the microstructure of the present invention described below may be removed, or micropore penetration processing may be performed.

<Dissolution of aluminum substrate>
For the dissolution of the aluminum substrate after the anodizing treatment under a constant current, a treatment solution is used in which the anodized film (alumina) is difficult to dissolve and aluminum is easily dissolved.
That is, the aluminum dissolution rate is 1 μm / min or more, preferably 3 μm / min or more, more preferably 5 μm / min or more, and the anodic oxide film dissolution rate is 0.1 nm / min or less, preferably 0.05 nm / min or less, more preferably Uses a treatment liquid having a condition of 0.01 nm / min or less.
Specifically, a treatment that includes at least one metal compound having a lower ionization tendency than aluminum and has a pH of 4 or less and 8 or more, preferably 3 or less and 9 or more, more preferably 2 or less and 10 or more. I do.

Such a treatment liquid is based on an acid or alkali aqueous solution, for example, manganese, zinc, chromium, iron, cadmium, cobalt, nickel, tin, lead, antimony, bismuth, copper, mercury, silver, palladium, platinum, A gold compound (for example, chloroplatinic acid), a fluoride thereof, a chloride thereof, or the like is preferably used.
Among them, an acid aqueous solution base is preferable, and it is preferable to blend a chloride.
In particular, a treatment liquid (hydrochloric acid / mercury chloride) in which mercury chloride is blended with an aqueous hydrochloric acid solution and a treatment liquid (hydrochloric acid / copper chloride) in which copper chloride is blended with an aqueous hydrochloric acid solution are preferable from the viewpoint of treatment latitude.
The composition of such a treatment liquid is not particularly limited, and for example, a bromine / methanol mixture, a bromine / ethanol mixture, aqua regia and the like can be used.

In addition, the acid or alkali concentration of such a treatment liquid is preferably 0.01 to 10 mol / L, and more preferably 0.05 to 5 mol / L. Furthermore, the treatment temperature using such a treatment liquid is preferably −10 ° C. to 80 ° C., and preferably 0 ° C. to 60 ° C.

In the production method of the present invention, the aluminum substrate is dissolved by bringing the aluminum substrate after the anodizing treatment step into contact with the treatment liquid described above. The method of making it contact is not specifically limited, For example, the immersion method and the spray method are mentioned. Of these, the dipping method is preferred. The contact time at this time is preferably 10 seconds to 5 hours, more preferably 1 minute to 3 hours.

<Removal of bottom of anodized film (penetration treatment)>
The following treatment (2-a) or (2-b) is preferably performed.
(2-a) A treatment (chemical dissolution treatment) in which an aluminum substrate having an anodized film is dissolved using acid or alkali and the pores are penetrated by micropores.
(2-b) A process of mechanically polishing an aluminum substrate having an anodized film so as to pierce holes by micropores (mechanical polishing process).

[(2-a) Chemical dissolution treatment]
In the chemical dissolution treatment, specifically, for example, after the anodizing treatment step, an aluminum substrate (portion represented by reference numeral 12b in FIG. 3D) is melted, and further, the bottom portion of the anodized film ( In FIG. 3D, the portion represented by reference numeral 18d) is removed, and the holes by the micropores are made to penetrate. The bottom part of the anodized film after the aluminum substrate is dissolved is removed by dipping in an acid aqueous solution or an alkali aqueous solution. By removing the bottom anodic oxide film, the pores by the micropores penetrate.

The bottom of the anodized film is removed by pre-soaking in a pH buffer solution and filling the hole with the pH buffer solution from the opening side of the micropore, and then on the opposite side of the opening, that is, on the bottom of the anodized film. It is preferably carried out by a method of contacting with an acid aqueous solution or an alkali aqueous solution.

In the case of using an acid aqueous solution, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid or a mixture thereof. The concentration of the acid aqueous solution is preferably 1 to 10% by mass. The temperature of the aqueous acid solution is preferably 25 to 40 ° C.
On the other hand, when using an alkaline aqueous solution, it is preferable to use an aqueous solution of at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The temperature of the alkaline aqueous solution is preferably 20 to 35 ° C.

Specifically, for example, a 50 g / L, 40 ° C. phosphoric acid aqueous solution, a 0.5 g / L, 30 ° C. sodium hydroxide aqueous solution, or a 0.5 g / L, 30 ° C. potassium hydroxide aqueous solution is suitably used. It is done.

The immersion time in the acid aqueous solution or alkali aqueous solution is preferably 8 to 120 minutes, more preferably 10 to 90 minutes, and further preferably 15 to 60 minutes.
Moreover, when immersing in a pH buffer solution beforehand, the buffer solution corresponding to the acid / alkali mentioned above is used appropriately.

[(2-b) Mechanical polishing treatment]
In the mechanical polishing treatment, specifically, for example, after the anodizing treatment step, an aluminum substrate (portion represented by reference numeral 12b in FIG. 3D) and an anodized film in the vicinity of the aluminum substrate (FIG. 3). In (D), the portion represented by reference numeral 18d) is mechanically polished and removed, thereby penetrating the holes by the micropores.
In the mechanical polishing treatment, known mechanical polishing treatment methods can be widely used. For example, the mechanical polishing exemplified for the mirror finish processing can be used. However, it is preferable to perform a chemical mechanical polishing (CMP) process because the precision polishing rate is high. For the CMP treatment, a CMP slurry such as PNINERLITE-7000 manufactured by Fujimi Incorporated, GPXHSC800 manufactured by Hitachi Chemical Co., Ltd., CL-1000 manufactured by Asahi Glass (Seimi Chemical) Co., Ltd. can be used.

By these penetration processing steps, a structure in which the aluminum substrate 12b and the barrier layer 18d shown in FIG. 3D are eliminated, that is, a fine structure through which the micropores pass is obtained.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

Example 1
1. Electrolytic polishing treatment A high-purity aluminum substrate (Sumitomo Light Metal Co., Ltd., purity 99.99 mass%, thickness 0.4 mm) was cut in an area of 10 cm square, and using an electrolytic polishing liquid having the following composition, a voltage of 10 V, liquid The electropolishing treatment was performed at a temperature of 65 ° C. The cathode was a carbon electrode, and the power source was GPO-250-30R (manufactured by Takasago Seisakusho).
<Electrolytic polishing liquid composition>
・ 85 mass% phosphoric acid (Wako Pure Chemical Industries, Ltd.) 1320mL
・ 600 mL of sulfuric acid
・ Pure water 80mL
2. Degreasing treatment The sample after the polishing treatment obtained above was degreased by immersing it for 10 to 60 seconds under the condition of a liquid temperature of 60 ° C. using a degreasing treatment liquid having the following composition. The obtained surface has an average surface roughness Ra,
It was 0.1 μm or less and the glossiness was 50% or more.
<Degreasing solution composition>
1.75 mol / L sodium hydroxide 0.16 mol / L sodium nitrate 3. Ordered Anodizing Treatment The sample obtained above was subjected to a constant voltage anodizing treatment with an electrolyte of 0.30 mol / L succinic acid aqueous solution for 45 hours under conditions of a voltage of 252 V and a liquid temperature of 0 ° C.
4). Film dissolution treatment The sample obtained above was immersed for 12 hours under the condition of a liquid temperature of 60 ° C. using an oxide film removal treatment liquid having the following composition to perform an oxide film removal treatment.
<Oxide film removal liquid composition>
0.16 mol / L chromium oxide 0.62 mol / L phosphoric acid Anodizing treatment The sample obtained above was subjected to anodizing treatment in the same manner except that the treatment time was 43 hours.
6). Calculation of degree of ordering The sample after the film dissolution treatment obtained above was subjected to gold vapor deposition for 2 minutes using a sputtering apparatus, and micropores were formed in a field of view 7500 times using a scanning microscope. The unevenness on the aluminum substrate caused by the above was observed. From the irregularities on the aluminum substrate, the values of A and B in the general formula (1) are visually observed, the degree of ordering on the bottom surface defined by the general formula (1) is calculated, and the bottom Table 1 shows the degree of ordering.
7). Micropore cycle and thickness measurement The micropore cycle is a cross section of the sample obtained by anodizing, observed with FE-SEM (S-900, manufactured by Hitachi, Ltd.), and a photograph (150,000 times). In other words, it is a value obtained by measuring the period of 25 or more micropores and averaging them. The micropore thickness was also measured and averaged in the same manner.

(Example 2)
3. The electrolytic conditions for the ordered anodizing treatment are as follows: a constant voltage anodizing treatment is carried out for 47 hours with a 0.3 mol / L aqueous solution of citric acid and a voltage of 375 V and a solution temperature of 0 ° C .; Example 2 was obtained in the same manner as in Example 1 except that the treatment time in the anodizing treatment was 45 hours, and the scanning microscope observation field of view in the calculation of the degree of ordering was 4000 times.
(Example 3)
3. The electrolytic conditions for the ordered anodizing treatment are as follows: a constant voltage anodizing treatment is carried out for 49 hours using a 0.03 mol / L phthalic acid aqueous solution at a voltage of 320 V and a liquid temperature of 0 ° C .; Example 3 was obtained in the same manner as in Example 1 except that the treatment time in the anodizing treatment was 47 hours and the scanning microscope observation field of view in the calculation of the degree of ordering was 5000 times.
Example 4
3. above. The electrolytic condition of the ordered anodizing treatment is a constant voltage anodizing treatment for 17 hours with a 0.1 mol / L tartaric acid aqueous solution under the conditions of a voltage of 263 V and a liquid temperature of 5 ° C. Example 4 was obtained in the same manner as in Example 1 except that the treatment time in the anodizing treatment was 20 hours.

(Comparative Example 1)
3. above. As the electrolytic condition of the ordered anodizing treatment, a constant voltage anodizing treatment was performed for 8 hours with 0.1 mol / L succinic acid electrolyte solution under a voltage of 40 V and a liquid temperature of 20 ° C. The treatment time in the anodizing treatment is 9 hours, and the above 6. Comparative Example 1 was obtained in the same manner as in Example 1 except that the scanning microscope observation field for calculating the degree of ordering was set to 10000 times.
(Comparative Example 2)
3. above. As the electrolytic conditions for the ordered anodizing treatment, a constant voltage anodizing treatment was performed for 8 hours with an electrolyte solution of 0.5 mol / L oxalic acid at a voltage of 40 V and a liquid temperature of 15 ° C. The treatment time in the anodizing treatment is 9 hours, and the above 6. Comparative Example 2 was obtained in the same manner as in Example 1 except that the scanning microscope observation field for calculating the degree of ordering was 10,000 times.

(Comparative Example 3)
3. above. As the electrolytic conditions for the ordered anodizing treatment, a constant voltage anodizing treatment was performed for 0.3 hours with a 0.5 mol / L oxalic acid electrolytic solution at a voltage of 195 V and a liquid temperature of 0 ° C. Comparative Example 3 was obtained in the same manner as in Example 1 except that the treatment time in the anodizing treatment was 0.3 hour. The formed anodized film “burned”. ("Burning" refers to a phenomenon in which local film growth occurs and uniform film formation does not occur). Therefore, the calculation of the micropore period, the micropore thickness, and the degree of bottom ordering cannot be performed.
(Comparative Example 4)
3. above. The processing time of the ordered anodizing treatment is 10 hours, and the above 5. Comparative Example 4 was obtained in the same manner as in Example 1 except that the treatment time in the anodizing treatment was 11 hours.

2

Oxide film

3, 16a, 16b, 16c, 16d Micropore 4 Bottom surface 5 Surface 6 Micropore axial distance 7 Micropore width 8 Micropore diameter 9

Micropore center distance

12, 12a, 12b , 12c,

12d Aluminum substrate

14, 14a, 14b, 14c, 14d Anodized film 18d Barrier layer 20

Microstructure

101, 102, 104, 105, 107, 108

Micropore

103, 106, 109 yen

Claims

A fine structure made of an anodized film of aluminum or an aluminum alloy, wherein the order of the plurality of micropores defined by the following general formula (1) is 70% or more on the bottom surface, and the distance between the centers of the micropores Is a microstructure having a micropore of not less than 600 nm and an axial length of the micropore of not less than 50 μm:
General formula (1)
Ordering degree (%) = B / A × 100
In the general formula (1), A represents the total number of micropores in the measurement range. B, when a circle with the shortest radius inscribed in the edge of the other micropore is drawn from the center of the cross section perpendicular to the major axis of one micropore, the micropores other than the micropore are inside the circle. This represents the number in the measurement range of the one micropore that will contain six pore centers.
2. The microstructure according to claim 1, wherein a distance between centers of micropores of the microstructure is 600 nm to 1200 nm.
The aluminum or aluminum alloy plate is anodized by applying a voltage of 195 V or more in an acidic aqueous solution containing an aliphatic carboxylic acid having 3 or more carbon atoms or an aromatic carboxylic acid. A manufacturing method of a fine structure.
The carboxylic acid is at least one selected from the group consisting of malonic acid, succinic acid, adipic acid, tartaric acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, and terephthalic acid. The manufacturing method of the described microstructure.