JP5373745B2 - Method for producing aluminum material for electrolytic capacitor electrode having excellent etching characteristics, electrode material for aluminum electrolytic capacitor, and aluminum electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an aluminum electrode material for an electrolytic capacitor excellent in switching characteristics, which can surely increase the expanded surface rate to increase the electrostatic capacitance by forming uniform etched pits in a high density and starting the deep etching from these pits to make coupling hard within a tunnel. <P>SOLUTION: The method for producing the aluminum electrode material includes the steps of: anodizing an aluminum material 1 in such a state as to align the resin spheres 2 on the surface of the aluminum material 1; and exposing outside, the aluminum base material 5 of the fine recessed bottom in which the resin spheres have existed by sequentially or simultaneously removing the resin spheres 2 and the anodized film 3 after anodization and making a peripheral anodized film remain. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for producing an aluminum material for an electrolytic capacitor electrode excellent in etching characteristics, an electrode material for an aluminum electrolytic capacitor, and an aluminum electrolytic capacitor, which are suitably used as an electrode material having a high capacitance and excellent bending strength.

  In this specification, the term “aluminum” is used to include the alloy thereof, and the aluminum material includes a foil, a plate, and a molded body using these.

  Usually, the aluminum material used for the electrode material for electrolytic capacitors is subjected to an etching process in order to increase the surface expansion ratio and improve the capacitance. And, as the number of etch pits formed by the etching process increases, the surface expansion ratio increases as the number of etch pits increases, so that various processes are performed on the aluminum material as a pre-process of the etching process in order to improve the etching characteristics. Yes.

  For example, control of (100) crystal orientation, addition of trace elements such as Cu and Pb to an aluminum material, degreasing cleaning before final annealing, formation treatment of a crystalline oxide film by final annealing, etc. (non-patent document) 1, patent documents 1-3).

  In addition, attempts have been made in the past to attach foreign substances or mechanically form defects to improve electrostatic capacity (Patent Documents 4 to 7).

  Patent Document 8 describes applying ink containing metal powder.

  Further, as an example aiming at uniform etch pits using a resin ball, Patent Document 9 discloses a method of etching after a resin ball is attached by static electricity and fixed by thermocompression bonding or the like.

  Further, Patent Document 10 discloses an example in which unevenness is imparted by anodizing using resin balls and the resin balls are removed.

  Furthermore, as a method for imparting a metal element different from aluminum to the aluminum surface and controlling the distribution of etch pits, Patent Document 11 discloses that aluminum is mixed by rolling and mixed with organic molecules bonded with Cu in a lubricating oil for rolling. A method of attaching to the surface is described, and Patent Document 12 describes a method of regularly attaching a metal compound by dot printing.

Kenshiro Yamaguchi: Light Metal, 35 (1985), P365 JP 2002-239773 A Japanese Patent Publication No. 58-34925 Japanese Patent Laid-Open No. 3-122260 Japanese Patent Publication No. 5-28486 Japanese Unexamined Patent Publication No. 63-157882 Japanese Patent No. 2545429 Japanese Patent Publication No.7-19732 Japanese Patent Publication No. 7-109036 Japanese Patent Laid-Open No. 8-138977 Japanese Unexamined Patent Publication No. 63-220512 JP-A-8-269601 JP 2004-266024 A

  However, simply increasing the number and length of each etch pit is approaching the limit of capacity improvement. In order to improve the surface expansion ratio of the aluminum material, it is necessary to reduce local etching, non-etching, and surface dissolution, and to generate etch pits uniformly and densely on the etched surface. 1. The methods described in Patent Documents 1 to 3 are not sufficient in that etch pits are uniformly generated at high density, and cannot meet the increasing demand for capacitance.

  Since the current aluminum material cannot control the distribution of pitting pits during the etching process, the tunnels of the etch pits are combined and the surface expansion ratio does not reach the ideal state. For this reason, the current capacitance remains at 50 to 65% of the ideal capacitance.

  In addition, in the techniques described in Patent Documents 4 to 7 in which foreign substances are attached or mechanical defects are formed, uniform nucleation cannot be realized, and high capacitance is not realized.

  In addition, as in Patent Document 8, in the method of applying ink containing metal powder, a strong oxide film is formed on the surface of the metal element, and diffusion to aluminum does not proceed, or between aluminum and metal powder. Since the potential difference required for triggering the generation of etch pits cannot be secured, a sufficient effect cannot be achieved.

  Further, in the method of Patent Document 9 aiming at uniform etch pits using resin balls, masking for controlling the distribution of etch pits is not sufficient.

  In addition, in the method of Patent Document 10 in which unevenness is imparted by anodizing treatment using a resin sphere and the resin sphere is removed, a natural oxide film at a portion where the resin sphere and aluminum are in contact with each other or a contact portion is wrapped around. There was a problem that the anodized film became an obstacle to etching, and on the contrary, an uneven distribution of etch pits was generated.

  Further, in the methods of Patent Document 11 and Patent Document 12 in which a metal element different from aluminum is applied to the aluminum surface and the distribution of etch pits is controlled, the former does not have a regular distribution. Even if it becomes possible, the distribution cannot be changed, and since the latter part is not actively masked except for the metal element adhesion part, both are insufficient for controlling the etch pit nuclei. there were.

  The present invention has been made in view of such a technical background, and etch pits are formed with high density and uniformity, and the etching pits are deeply formed from the starting point and are reliably etched by being less likely to cause bonding in the tunnel. To provide a method for producing an aluminum material for an electrolytic capacitor electrode excellent in etching characteristics, an electrode material for an aluminum electrolytic capacitor, and an aluminum electrolytic capacitor capable of further increasing the surface expansion ratio and further increasing the capacitance. Objective.

  As a result of intensive studies in view of the above problems, the present inventors have made anodization with regular irregularities by anodizing an aluminum material subjected to electrolytic etching in a state where resin balls are arranged on the surface of the aluminum material. After forming the film and then removing the resin spheres to form fine recesses in the anodic oxide film, an exposed portion of the aluminum base is formed at the portion corresponding to the bottom of the original resin sphere even if the film is sequentially dissolved. By leaving the surrounding anodic oxide film, it becomes possible to effectively form nuclei as starting points of etch pits, thus completing the present invention.

That is, the said subject is solved by the following means.
(1) The step of anodizing the resin spheres arranged on the surface of the aluminum material, and after the anodizing treatment, the resin spheres and the anodized film are removed sequentially or simultaneously so that the resin spheres are present. A method for producing an aluminum material for an electrolytic capacitor electrode excellent in etching characteristics, comprising: exposing an aluminum base at the bottom of a fine recess, and leaving a surrounding anodic oxide film.
(2) The method for producing an aluminum material for electrolytic capacitor electrodes according to item 1 above, wherein the formation thickness of the anodized film is from 0.3 to 3 layers of the resin sphere diameter.
(3) The method for producing an aluminum material for an electrolytic capacitor electrode according to claim 1 or 2, wherein the method for removing the anodic oxide film is a wet etching method using acid or alkali, or a dry etching method.
(4) The etching characteristics according to any one of items 1 to 3, further comprising a step of attaching at least one of a metal different from aluminum, a solvent-soluble metal compound, and a metal complex to the exposed aluminum substrate. The manufacturing method of the aluminum material for electrolytic capacitor electrodes.
(5) The method for producing an aluminum material for an electrolytic capacitor electrode according to item 4, wherein the metal adhered to the exposed aluminum substrate is a metal nobler than aluminum.
(6) At least one of a metal, a solvent-soluble metal compound, and a metal complex is attached to the exposed aluminum substrate, and then the metal element is diffused from the surface of the aluminum substrate to the inside of the aluminum material by heat treatment. 5. A method for producing an aluminum material for electrolytic capacitor electrodes having excellent etching characteristics as described in 4 above.
(7) The method for producing an aluminum material for electrolytic capacitor electrodes excellent in etching characteristics according to any one of items 1 to 6 above, wherein the average diameter of the resin spheres is 0.2 μm or more and 5 μm or less.
(8) By using as a trigger a dissimilar metal directly or adhering or diffusing to an aluminum base material of an aluminum material exposed from a part of an anodized film formed using a resin ball, An electrode material for an aluminum electrolytic capacitor, characterized in that a large number of etch pits regularly arranged by a technique are formed, and 50% or more of these etch pits are defined in a circle equivalent diameter range of 0.4 to 10 μm.
(9) The electrode material for an aluminum electrolytic capacitor as described in 8 above, wherein the purity of the aluminum material is 99.9% by mass or more.
(10) An aluminum electrolytic capacitor in which the electrode material for an electrolytic capacitor as described in 8 or 9 above is used.

  According to the invention described in the preceding item (1), etch pits can be formed with high density and uniformity on the exposed portion of the aluminum base material dispersed at high density by etching, and the bending strength and the surface expansion ratio are increased. An aluminum material for an electrolytic capacitor electrode that can increase the capacitance can be manufactured.

  According to the invention described in (2) above, since the formation thickness of the anodized film is from 0.3 to 3 layers of the resin sphere diameter, it is possible to reliably cover other than the aluminum base exposed portion without waste. Etch pits can be prevented from being formed at portions other than the exposed portion of the aluminum substrate, so that etch pits can be reliably formed at the exposed portion of the aluminum substrate.

  According to the invention described in item (3) above, since the method for removing the anodic oxide film is a wet etching method using acid or alkali, or a removing method using dry etching, the aluminum substrate exposed portion can be easily formed. .

  According to the invention described in the preceding item (4), by forming a metal different from aluminum, a solvent-soluble metal compound and a metal complex on the exposed aluminum base, an etch pit is formed using this adhesion portion as a trigger. Therefore, an aluminum material that can form etch pits more reliably and uniformly can be manufactured.

  According to the invention described in the preceding item (5), since the metal adhered to the aluminum substrate is a noble metal than aluminum, it is possible to produce an aluminum material that can more reliably exhibit the trigger effect of etch pit formation. It becomes.

  According to the invention described in the preceding item (6), at least one of a metal, a solvent-soluble metal compound, and a metal complex is attached to the aluminum substrate, and then the metal is introduced from the surface of the aluminum substrate to the inside of the aluminum material by heat treatment. Since the element is diffused, it is possible to produce an aluminum material that can form etch pits more reliably and uniformly using this diffusion portion as a trigger.

  According to the invention described in item (7) above, since the average diameter of the resin spheres is 0.2 μm or more and 5 μm or less, the exposed aluminum substrate corresponding to the original arrangement position of the resin spheres is made dense and uniform. It is possible to manufacture an aluminum material that can be formed, and consequently etch pits can be formed with high density and uniformity.

  According to the invention described in the preceding item (8), a foreign metal adhering or diffusing directly or on an aluminum substrate exposed from a part of an anodized film formed by using a resin ball is triggered. As a result, a large number of etch pits regularly arranged by an electrochemical method are formed, and 50% or more of these etch pits are defined in a circle equivalent diameter range of 0.4 to 10 μm. The electrode material for an aluminum electrolytic capacitor having a high electrostatic capacity having a large number of uniformly distributed etch pits can be obtained.

  According to the invention described in item (9) above, since the purity of the aluminum material is 99.9% by mass or more, a chemical conversion film with few defects can be formed when the chemical conversion film is formed after etching.

  According to the invention described in item (10) above, an aluminum electrolytic capacitor having a large capacitance can be obtained.

It is typical sectional drawing for demonstrating the manufacturing method of the aluminum material which concerns on one Embodiment of this invention.

Next, the configuration of the present invention and the reason thereof will be described.
[About aluminum materials]
The aluminum material used in the present invention only needs to be capable of forming tunnel pits. For example, the thickness may be within a range that can sufficiently ensure the strength of the aluminum foil after etching, and is 0.005 to 0.6 mm, preferably 0.006 to 0.25 mm, and more preferably 0.007 to 0.18 mm. It is.

  Examples of the trace element in the aluminum material include Si, Fe, Cu, Mn, Mg, Zn, Ti, V, Ga, and Zr. However, in the present invention, the type and amount of the element are not particularly limited. However, in order to prevent chemical conversion film defects, it is better to have as few trace elements as possible, and it is desirable to use an aluminum material having a purity of 99.9% by mass or more. In addition, the addition of Cu, Mg, Zn, Pb, Sn, Sb and the like as elements for improving the etching characteristics has been conventionally proposed for aluminum materials for electrolytic capacitors. Also in the present invention, there is no problem in adding these elements within a range not causing the above-mentioned chemical conversion film defects.

  In addition, as will be described later, the heat treatment of the aluminum material in the case of diffusing the metal element is combined with the high-temperature annealing at 450 to 600 ° C. necessary for forming a high cubic texture which has been conventionally proposed. Of course, diffusion treatment at 300 ° C. or higher necessary for thermal diffusion may be performed separately within a range that does not cause abnormal dissolution during etching due to precipitation of Fe or Si. Specific conditions for the heat treatment are, for example, 500 ° C. × 1-8 h when the metal element to be diffused is Cu, 480 ° C. × 0.5-2 h when Pb is used, and 550 ° C. × when Fe is used. Conditions such as 10 to 30 h can be given. Of course, other than these conditions, the objective can be achieved.

Further, the shape of the aluminum material may be a coiled shape or a cut sheet, and is not limited at all.
[Production method]
In the present invention, as shown in FIG. 1 (a), the step of anodizing with the resin balls 2 arranged on the surface of the aluminum material 1, and after the anodizing treatment, FIG. 1 (b) (c) As shown in FIG. 4, the resin sphere 2 and the anodic oxide film 3 are removed sequentially or simultaneously to expose the aluminum base at the bottom of the fine recess 4 where the resin sphere 2 was present, and the surrounding anodic oxide film 3 is performed.

  The resin sphere 2 is not particularly limited as long as it can be arranged on the surface of the aluminum material 1 and does not cause changes such as dissolution, elution, and swelling in the anodizing treatment and cleaning treatment. Good. As an example, PS (polystyrene), PP (polypropylene), etc. can be mentioned.

  The average diameter of the resin spheres 2 is preferably 0.2 μm or more and 5 μm or less. If it is less than 0.2 μm, the interval between etch pits to be formed thereafter becomes too narrow, and the coalescence of the etch pits increases, and the capacitance may decrease instead. On the other hand, if the thickness exceeds 5 μm, the density of etch pits may become too low, and the capacitance may decrease. A particularly preferable average diameter of the resin spheres 2 is 0.5 to 3 μm.

  The resin balls 2 may be arranged by being naturally placed on the surface of the aluminum material 1 without an artificial joining force such as adhesion, fusion, or welding.

  In addition, as a pretreatment for the anodizing treatment, electrolytic polishing, chemical polishing, mechanical polishing, etc. are performed for the purpose of reducing unevenness due to rolling streaks formed by rolling and improving the adhesion of the resin balls 2 to the surface of the aluminum material 1. You may perform the smoothing process by.

  The type and conditions of the anodizing treatment are not particularly limited, and a known treatment method and treatment conditions may be adopted. The anodized film 3 plays a role of preventing the aluminum base from being exposed except for the portion where the resin spheres 2 were present. For this purpose, the thickness of the anodic oxide film 3 is preferably set to a thickness of 0.3 to 3 layers of the diameter of the resin sphere 2. If it is less than 0.3 layers, the film thickness is too thin, and there is a possibility that the aluminum substrate is exposed at a part other than the resin ball arrangement part by the subsequent film removal process. Even if the thickness exceeds three layers, the effect of preventing the exposure of the aluminum substrate is saturated, resulting in a wasteful treatment.

  The removal of the resin sphere 2 may be generally performed by dissolving the resin sphere 2. The solution may be appropriately selected depending on the type of the resin sphere 2. For example, when the resin sphere is made of PS (polystyrene), toluene or the like may be used. By removing the resin sphere 2, a large number of fine recesses 4 are formed in the anodized film 3 as shown in FIG.

  Next, the anodic oxide film 3 is sequentially removed in the thickness direction. As a removal method, a chemical or electrochemical method using an acid or an alkaline solution or a dry method such as dry etching is used. A method of removing by the method can be exemplified. By removing the anodized film 3 uniformly in the thickness direction over the entire surface of the aluminum material 1, the anodized film 3 disappears at an early stage at the bottom of the fine concave portion 4 having a thin thickness. The exposed portion 5 of the aluminum substrate is formed, and the anodic oxide film 3 remains around the exposed portion 5.

  In addition, you may perform the removal of the resin ball | bowl 2, the removal of the anodic oxide film 3, and the exposure of an aluminum substrate by the same process by dry etching.

  The exposed portion 5 of the aluminum base is preferably equivalent to a circle and has a diameter of 0.05 to 2.5 μm, and the total area ratio of the exposed portion 5 to the surface of the aluminum material 1 is 10 to 50%. Good. If the total area ratio of the exposed portions 5 is less than 10%, the exposed portions 5 may be dispersed in a rough state, and the number of etch pits may be reduced. On the other hand, when the area ratio exceeds 50%, the number of etch pits increases excessively, and tunnels due to the etch pits are combined, so that there is a possibility that a sufficient area expansion rate cannot be obtained. A particularly preferable total area ratio of the exposed portion 5 of the aluminum base is 15 to 40%.

  After forming the exposed portion 5 of the aluminum base as described above, preferably, as shown in FIG. 1D, the aluminum base exposed portion 5 is used for generating an etch pit made of a metal, a metal compound, or a metal complex different from aluminum. The trigger substance 6 is preferably attached. Examples of the metal compound include sulfates, nitrates, and chelate compounds in addition to compounds with simple elements such as chlorides, sulfides, and fluorides. Moreover, a hydroxide may be sufficient. These can be decomposed during heating and heating to liberate metal elements and diffuse into aluminum, thereby triggering the generation of etch pits during the subsequent etching process.

  Further, the metal may be basically an element that causes a potential difference from aluminum as a single metal. Elements that are more noble than aluminum, such as Fe, Ni, In, Sn, Pb, Cu, and Ag, and conversely elements that are lower than aluminum, such as Mg and Li, can be used. The potential difference may be 100 mV or more at the standard electrode potential.

These elements exhibit an effect even when attached to the surface of the aluminum material 1 as it is, but are diffused in the aluminum material 1 by performing the heat treatment as described above, and as shown in FIG. A concentrated layer 7 is formed on the surface. As a result, the occurrence of non-uniformity of etch pits can be suppressed and the effect of controlling the dispersibility of etch pits can be further enhanced. At that time, the noble element has an effect of promoting the generation of etch pits in the boundary area with aluminum, and the base element tends to be the starting point of the etch pit generation in the boundary area or itself. The present invention uses this principle and aims to more actively control the distribution of etch pits.
[Electrolytic etching]
In expanding the surface of the aluminum material manufactured as described above, an electrolytic etching treatment is performed in an electrolytic solution in which phosphoric acid, sulfuric acid, nitric acid, or the like is added to an aqueous solution containing chlorine ions. Basically, it is desirable to perform direct current etching that is tunnel-etched, but this is not limited to the initial etching nucleation. That is, the initial etching for using the diffused metal as effective nuclei and the subsequent etching for forming tunnel pits should be performed without any problem and should be positively recommended.

  The etch pit diameter obtained by etching is preferably defined in the range of the equivalent circle diameter of 0.4 to 10 μm, but the appropriate etch pit diameter varies depending on the formation voltage. The etch pit diameter at medium pressure (formation voltage 200-500V) is preferably 0.7 to 1.5 [mu] m in terms of equivalent circle diameter, and the distance is preferably 1 to 4 [mu] m in the distance between etch pit centers. In the case of a high voltage (formation voltage of 500 V or more), the etch pit diameter is preferably 2 to 3 μm in terms of the equivalent circle diameter, and the distance is preferably 3 to 15 μm in terms of the distance between the etch pit centers.

The above-mentioned etch pit diameter and interval show average values, and it is sufficient that 50% or more of all etch pits are within this range, and some of them are outside this range.
[Chemical conversion treatment]
When used as an anode material, a chemical conversion treatment is performed. The chemical conversion treatment can be performed by various methods, but the conditions for the chemical conversion treatment are not particularly limited. For example, using an electrolytic solution containing at least one of oxalic acid, adipic acid, boric acid, phosphoric acid, sodium silicate, etc., the electrolytic solution concentration is 0.05 mass% to 20 mass%, the temperature is 0 ° C to 90 ° C, The current density is 0.1 mA / cm ^{2 to} 1 A / cm ² , and the voltage is set in accordance with the conversion voltage of the aluminum material to be processed. More preferably, the electrolyte concentration is 0.1 wt% to 15 wt%, temperature of 20 ° C. to 70 ° C., a current density of ^{1mA / cm 2 ~100mA / cm 2} , the chemical conversion time is in the range of 30 minutes It is better to select the conditions.

  After the chemical conversion treatment, for example, a phosphoric acid immersion treatment for improving water resistance, a heat treatment for strengthening the film, or an immersion treatment in boiling water can be performed as necessary.

Example 1
Preparation of aluminum material PS resin balls having an average diameter of 1 μm are arranged on the surface of a 150 μm-thick high-purity aluminum soft foil material having the composition shown in Table 1 (1) prepared by a conventional method, and 0.5 mol / l Using an aqueous boric acid-0.05 mol / l borax solution, anodization was performed by a constant current electrolysis method at a liquid temperature of 20 ° C. and a current density of 10 A / m ² to form a 2 μm anodic oxide coating.

  Next, the resin balls made of PS are dissolved and removed using toluene to form a film having fine recesses, and then immersed in a 1% by mass Na0H aqueous solution at 50 ° C. for a predetermined time. The aluminum base at the bottom of the fine recess where the slag was present was exposed.

Table 2 shows the area ratio of all exposed portions to the surface of the aluminum material. The area ratio was measured by observing the composition image with a scanning electron microscope and performing binarization.
Etching treatment process The aluminum material obtained above was subjected to a 30 sec immersion treatment at a liquid temperature of 75 ° C. using a mixture of 1.0 mol / l HC1 and 3.5 mol / l H ₂ SO ₄ , Primary electrolytic treatment was performed at a current density of 0.2 A / cm ² for 120 seconds.

  Furthermore, chemical etching was performed at 90 ° C. for 900 seconds with the liquid having the same composition, washed with water and dried to complete the etching.

  Next, chemical conversion treatment was performed in a boric acid bath 500 V, and the capacitance was measured. The results are shown in Table 2. The electrostatic capacity was relatively evaluated based on 100 as a comparative example.

The etch pit diameter, etch pit interval, and etch pit density were measured by electropolishing the etched foil surface by about 5 μm, observing the surface with a scanning electron microscope, and performing image analysis.
(Example 2)
Preparation of aluminum material PS resin balls having an average diameter of 1 μm are arranged on the surface of a 150 μm thick high-purity aluminum soft foil material having the composition shown in Table 1 (2) prepared by a conventional method, and 0.5 mol / l Using an aqueous boric acid-0.05 mol / l borax solution, anodization was performed by a constant current electrolysis method at a liquid temperature of 20 ° C. and a current density of 10 A / m ² to form a 2 μm anodic oxide coating.

  Next, the resin balls made of PS are dissolved and removed with toluene to form a film having fine recesses, and then immersed in a 5% by mass phosphoric acid aqueous solution at a bath temperature of 30 ° C. for a predetermined time to sequentially form the anodized film. It melt | dissolved and the aluminum base | substrate of the bottom part of the fine recessed part in which the resin ball existed was exposed. Table 2 shows the area ratio of all exposed portions to the surface of the aluminum material.

Next, it was immersed in an aqueous solution containing copper sulfate at a rate of 5 g / l, washed with water, held for 10 seconds in an electric furnace heated to 200 ° C., and dried.
Etching treatment process The aluminum material obtained above was subjected to a 30 sec immersion treatment at a liquid temperature of 75 ° C. using a mixture of 1.0 mol / l HC1 and 3.5 mol / l H ₂ SO ₄ , Primary electrolytic treatment was performed at a current density of 0.2 A / cm ² for 120 seconds.

  Furthermore, chemical etching was performed at 90 ° C. for 900 seconds with the liquid having the same composition, washed with water and dried to complete the etching.

Next, chemical conversion treatment was performed in a boric acid bath 500 V, and the capacitance was measured. The results are shown in Table 2. The electrostatic capacity was relatively evaluated based on 100 as a comparative example.
(Example 3)
Preparation of aluminum material PS resin balls having an average diameter of 2 μm are arrayed on the surface of a 150 μm thick high-purity aluminum soft foil material having the composition shown in Table 1 (3) prepared by a conventional method, and 0.5 mol / l Using an aqueous boric acid-0.05 mol / l borax solution, anodization was performed by a constant current electrolysis method at a liquid temperature of 20 ° C. and a current density of 10 A / m ² to form a 5 μm anodic oxide film.

  Next, the resin balls made of PS are dissolved and removed with toluene to form a film having fine recesses, and then immersed in a 1% by weight NaOH aqueous solution at 50 ° C. for a predetermined time to sequentially dissolve the anodized film. Thus, the aluminum base at the bottom of the fine concave portion where the resin ball was present was exposed. Table 2 shows the area ratio of all exposed portions to the surface of the aluminum material.

Next, after being immersed in an aqueous solution containing copper sulfate at a rate of 5 g / l, it was held in an electric furnace heated to 200 ° C. for 10 seconds, dried, and then heated in a nitrogen atmosphere at a rate of temperature increase of 80 ° C./h. Then, a heat treatment was performed at a holding temperature of 500 ° C. and a holding time of 30 minutes.
Etching treatment process The aluminum material obtained above was subjected to a 30 sec immersion treatment at a liquid temperature of 75 ° C. using a mixture of 1.0 mol / l HC1 and 3.5 mol / l H ₂ SO ₄ , Primary electrolytic treatment was performed at a current density of 0.2 A / cm ² for 120 seconds.

  Furthermore, chemical etching was performed at 90 ° C. for 900 seconds with the liquid having the same composition, washed with water and dried to complete the etching.

Next, chemical conversion treatment was performed in a boric acid bath 500 V, and the capacitance was measured. The results are shown in Table 2. The electrostatic capacity was relatively evaluated based on 100 as a comparative example.
Example 4
Preparation of aluminum material PS resin balls having an average diameter of 2 μm are arranged on the surface of a 150 μm thick high-purity aluminum soft foil material having the composition shown in Table 1 (4) prepared by a conventional method, and 0.5 mol / l Using an aqueous borate-0.05 mol / l borax solution, anodizing was performed by a constant current electrolysis method at a liquid temperature of 20 ° C. and a current density of 10 A / m ² , and a 0.5 μm anodic oxide film was formed. did.

Next, dry etching treatment was performed by an argon sputtering method, and the PS resin sphere and a part of the film were removed to expose the aluminum base at the bottom of the resin sphere. Table 2 shows the area ratio of all exposed portions to the surface of the aluminum material.
Etching treatment process The aluminum foil obtained above was subjected to a 30 sec dipping treatment at a liquid temperature of 75 ° C. using a mixture of 1.0 mol / l HC1 and 3.5 mol / l H ₂ SO ₄ , Primary electrolytic treatment was performed at a current density of 0.2 A / cm ² for 120 seconds.

  Furthermore, chemical etching was performed at 90 ° C. for 900 seconds with the liquid having the same composition, washed with water and dried to complete the etching.

Next, chemical conversion treatment was performed in a boric acid bath 500 V, and the capacitance was measured. The results are shown in Table 2. The electrostatic capacity was relatively evaluated based on 100 as a comparative example.
(Example 5)
Preparation of aluminum material PS resin balls having an average diameter of 2 μm are arranged on the surface of a 150 μm-thick high-purity aluminum soft foil material having the composition shown in Table 1 (1) prepared by a conventional method, and 0.5 mol / l Using an aqueous borate-0.05 mol / l borax solution, anodization was performed by a constant current electrolysis method at a liquid temperature of 20 ° C. and a current density of 10 A / m ² to form a 1 μm anodic oxide coating. .

  Next, the resin balls made of PS are dissolved and removed with toluene to form a film having fine recesses, and then immersed in a 1% by weight NaOH aqueous solution at 50 ° C. for a predetermined time to sequentially dissolve the anodized film. Thus, the aluminum base at the bottom of the fine concave portion where the resin ball was present was exposed. Table 2 shows the area ratio of all exposed portions to the surface of the aluminum material.

Next, it was immersed in an aqueous solution containing copper phthalocyanine tetrasulfonate tetrasodium (C ₃₂ H ₁₂ CuN ₈ Na ₄ O ₁₂ S ₄ ) at a rate of 6 g / l, and then ₁₀ sec in an electric furnace heated to 200 ° C. After holding and drying, a heat treatment was performed in a nitrogen atmosphere at a heating rate of 80 ° C./h, a holding temperature of 500 ° C., and a holding time of 30 minutes.
Etching treatment process The aluminum material obtained above was subjected to a 30 sec immersion treatment at a liquid temperature of 75 ° C. using a mixture of 1.0 mol / l HC1 and 3.5 mol / l H ₂ SO ₄ , Primary electrolytic treatment was performed at a current density of 0.2 A / cm ² for 120 seconds.

  Furthermore, chemical etching was performed at 90 ° C. for 900 seconds with the liquid having the same composition, washed with water and dried to complete the etching.

Next, chemical conversion treatment was performed in a boric acid bath 500 V, and the capacitance was measured. The results are shown in Table 2. The electrostatic capacity was relatively evaluated based on 100 as a comparative example.
(Comparative example)
Etching process The aluminum hard foil (150 μm) having the composition shown in Table 1 (1) prepared by a conventional method is heated in a nitrogen atmosphere at a heating rate of 80 ° C./h, a holding temperature of 500 ° C., and a holding time of 5 hours. And it was set as the soft foil.

Then, after using a mixed solution of 1.0 mol / l HC1 and 3.5 mol / l H ₂ SO ₄ for 30 sec at a liquid temperature of 75 ° C., 120 sec at a current density of 0.2 A / cm ² . The primary electrolytic treatment was performed.

  Furthermore, chemical etching was performed at 90 ° C. for 900 seconds with the liquid having the same composition, washed with water and dried to complete the etching.

  Next, chemical conversion treatment was performed in a boric acid bath 500 V, and the capacitance was measured to obtain a comparative example. The results are shown in Table 2 with the electrostatic capacity being 100.

  From Table 2, it can be seen that in Examples 1 to 5, the distribution of etch pits is made more uniform and the tunnel pit density is higher than in the comparative example, and the capacitance after formation is improved.

DESCRIPTION OF SYMBOLS 1 Aluminum material 2 Resin sphere 3 Anodized film 4 Fine recessed part 5 Aluminum base exposed part 6 Trigger substance 7 Concentrated layer

Claims (10)

A step of anodizing in a state where resin balls are naturally placed on the surface of the aluminum material; and
After the anodizing treatment, the resin balls and the anodized film are removed sequentially or simultaneously to expose the aluminum base at the bottom of the fine recesses where the resin balls existed, and the surrounding anodized film remains. When,
The manufacturing method of the aluminum material for electrolytic capacitor electrodes excellent in the etching characteristic characterized by including this. Formation thickness of the anodized film, a manufacturing method of excellent etching characteristics of claim 1 has a thickness from 0.3 times the average diameter of the resin ball up to three times electrolytic capacitor electrodes for aluminum material.   The method for producing an aluminum material for electrolytic capacitor electrodes with excellent etching characteristics according to claim 1 or 2, wherein the method for removing the anodized film is a wet etching method using acid or alkali, or a dry etching method. 4. The method according to claim 1, further comprising a step of attaching a trigger substance for generating etch pits made of at least one of a metal different from aluminum, a solvent-soluble metal compound, and a metal complex to the exposed aluminum base. The manufacturing method of the aluminum material for electrolytic capacitor electrodes excellent in the etching characteristic of description. Method of manufacturing an electrolytic capacitor electrode aluminum material having excellent etching characteristics of claim 4 trigger substance composed of the metal deposited on the aluminum base material which is exposed is a trigger substance consisting of noble metal than aluminum.   5. The metal element is diffused from the surface of the aluminum base to the inside of the aluminum material by attaching at least one of a metal, a solvent-soluble metal compound, and a metal complex to the exposed aluminum base, and then performing a heat treatment. The manufacturing method of the aluminum material for electrolytic capacitor electrodes excellent in the etching characteristic of description.   The method for producing an aluminum material for electrolytic capacitor electrodes having excellent etching characteristics according to any one of claims 1 to 6, wherein an average diameter of the resin spheres is 0.2 µm or more and 5 µm or less. A large number of etches regularly arranged on the surface of an aluminum material produced by performing an electrolytic etching process on the aluminum material for an electrolytic capacitor electrode produced by the production method according to claim 1. An electrode material for an aluminum electrolytic capacitor characterized in that pits are formed, and 50% or more of these etch pits are defined in a circle equivalent diameter of 0.4 to 10 μm.   The electrode material for an aluminum electrolytic capacitor according to claim 8, wherein the purity of the aluminum material is 99.9% by mass or more.   An aluminum electrolytic capacitor in which the electrode material for an electrolytic capacitor according to claim 8 or 9 is used.

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