JP7028481B2 - Electrode members for electrolytic capacitors and electrolytic capacitors - Google Patents

Description

The present invention relates to an electrode member for an electrolytic capacitor and an electrolytic capacitor.

The capacitance of the capacitor is proportional to the surface area of the dielectric formed on the electrode member. Therefore, as a method for increasing the capacitance of the electrolytic capacitor, it has been conventionally performed to increase the surface area of the electrode member used for the electrolytic capacitor. Specific methods thereof include, for example, roughening the surface of the electrode member and using a sintered body for the electrode member.

FIG. 15 is a diagram schematically showing a conventional electrolytic capacitor. In FIG. 15, the display of the separator is omitted. As shown in FIG. 15, the electrolytic capacitor includes an anode 1, a dielectric 2 formed on the anode 1, and an electrolyte 3 arranged adjacent to the dielectric 2 on the opposite side of the anode 1. And the cathode body 5 arranged so as to face the anode body 1 so as to sandwich the electrolyte 3 between the anode body 1 and the dielectric 4 formed on the cathode body 5 so as to be adjacent to the electrolyte 3. To prepare for.

The capacitance of the electrolytic capacitor is such that a capacitor composed of an anode 1, a dielectric 2 and an electrolyte 3 and a capacitor composed of an electrolyte 3, a dielectric (natural oxide film) 4 and a cathode body 5 are connected in series. It is the combined capacity when connected. Usually, a cathode body 5 having a sufficiently high capacitance as compared with the anode body 1 is used. Therefore, the capacitance of the electrolytic capacitor is greatly affected by the value of the capacitance of the capacitor composed of the anode 1, the dielectric 2, and the electrolyte 3.

No matter how complicated the surface of the anode 1 is, there is a portion where the dielectric 2 formed on the surface and the electrolyte 3 are not in contact with each other, that is, the impregnation of the electrolyte is sufficient. If this is not done, the capacitance of the electrolytic capacitor will be reduced accordingly.

Among electrolytic capacitors, the impregnation property of this electrolyte is particularly important for solid electrolytic capacitors that use a solid electrolyte such as a conductive polymer as the electrolyte.

FIG. 16 is a diagram schematically showing the degree of impregnation of a solid electrolyte in a conventional electrode member for an electrolytic capacitor. FIG. 16 mainly shows the contact state between the dielectric 2 and the electrolyte 3 shown in FIG. As shown in FIG. 16, no matter how large the surface area of the anode 1 is formed by forming a large number of fine irregularities on the surface of the anode 1, the size of the irregularities is compared with the diameter of the conductive polymer. If it is not sufficiently large, a portion where the solid electrolyte 6 as an electrolyte is not in contact with the dielectric 2 will be generated over a wide range. That is, the capacity appearance rate, which represents the ratio of the capacitance when impregnated with the solid electrolyte to the capacitance when impregnated with the electrolytic solution, becomes low.

Therefore, the following proposals have been made for electrode members for electrolytic capacitors, which are foil-shaped or plate-shaped.

According to Japanese Patent Application Laid-Open No. 2008-078303 (Patent Document 1), if the etching pit diameter is too small, the solid electrolyte is not sufficiently impregnated, and if a large one is also mixed, the solid electrolyte becomes non-uniform, resulting in an electrolytic capacitor. There was a problem that the ESR at that time became high. On the other hand, in Patent Document 1, at least one surface has an etching layer of 70 μm or more in the depth direction from the surface, and the etching layer has a planar cross section at a position deeper than 20 μm from the surface when measured by an image analyzer. We propose an aluminum electrode plate for an electrolytic capacitor in which the number of pits having a pit diameter of 0.01 to 1 μm when converted into a circle on each measurement surface is 70% or more of the total number of pits in the measurement surface.

In JP-A-2-288217 (Patent Document 2), a solid using a conductive polymer film composed of a conductive polymer film formed by chemical oxidation polymerization and a conductive polymer film formed on the conductive polymer film by electrolytic polymerization as a solid electrolyte. In the electrolytic capacitor, there is a problem that the capacitance obtained differs depending on the roughened electrode foil used. On the other hand, Patent Document 2 focuses on the relationship between the formation of the conductive polymer film and the roughening of the valve acting metal, and the maximum pit depth at which the conductive polymer film can be formed by chemical oxidation polymerization. We have found that, and have proposed a roughened electrode foil in which the pit depth of the valve acting metal on which the dielectric oxide film is formed is 16 μm or more on average.

Japanese Patent Application Laid-Open No. 2001-143972 (Patent Document 3) has a problem that it is not possible to meet the increasing demand for high capacitance simply by providing protrusions and dents on the foil surface. On the other hand, in Patent Document 3, a large number of primary dents having an opening diameter (d1) equivalent to a circle of 0.1 to 5 μm are formed on the surface thereof, and the maximum internal diameter of the primary dents is formed. (D2) has a shape in which the inside is bulged larger than the opening diameter (d1), and the condition that the opening diameter (d1) / maximum internal diameter (d2) is less than 0.9 is satisfied, and the inside is opened. The total number of those having one or more secondary dents and satisfying the condition that at least one opening diameter (d3) of the secondary dents is ½ or less of the opening diameter (d1) of the primary dents. We are proposing an aluminum foil for electrolytic capacitor electrodes that is present in 20% or more.

According to Japanese Patent Application Laid-Open No. 3-104207 (Patent Document 4), in the conventional combined etching of DC etching and AC etching, the average opening diameter of the tunnel-shaped pit by the DC etching in the previous stage is not sufficiently large, so that the AC etching in the subsequent stage is performed. However, there is a problem that etching hardly progresses on the inner wall surface of the tunnel-shaped pit, and only the surface portion of the electrode is uniformly melted, and the desired surface expansion effect cannot be obtained. On the other hand, in Patent Document 4, a pit having an opening diameter of less than 1 μm is formed by the first DC etching, and then the opening diameter is expanded to 1 μm to 4 μm by the second DC etching, and then AC etching is performed. We are proposing an etching method for electrodes for electrolytic capacitors.

In Japanese Patent Application Laid-Open No. 11-307400 (Patent Document 5), as a method for manufacturing an electrode foil for a solid electrolytic capacitor, a step of separating an etched portion that is etched by masking and an unetched portion that is not etched is first provided. However, as an etching method for the etching portion in this case, DC etching is performed, and then the etching is immersed in an electrolytic solution for AC etching to gradually increase the current density of AC etching, and then AC etching is performed with a constant current. Has been proposed.

The above is a bird's-eye view of the conventional technology from the viewpoint of capacitance, focusing on the capacitance appearance rate, but the characteristics required for electrolytic capacitors are not limited to capacitance. For example, in a practical capacitor, the dielectric is defective and is not a perfect insulator. Therefore, when a DC voltage is applied to the capacitor, a small amount of leakage current is generated, which may adversely affect the circuit. Therefore, there is a strong demand to keep the leakage current low, and the following proposals have been made so far.

In JP-A-2008-177199 (Patent Document 6) and JP-A-2008-177200 (Patent Document 7), when a foil-shaped electrode member is used, the width of the electrode is narrowed for miniaturization. However, the ratio of the area of the end face to the apparent area of the electrode increases accordingly, and the adverse effect of the dielectric of the end face formed by aging becomes remarkable. There was a problem that the leakage current of the capacitor became large. On the other hand, in Patent Document 6 and Patent Document 7, it is proposed to use an etched aluminum wire as an anode body and to wind a dielectric formed on the surface thereof in a spiral shape.

According to Japanese Patent Application Laid-Open No. 61-278124 (Patent Document 8), a sintered type capacitor using aluminum as an anode material is cheaper as a material than a capacitor using tantalum as an anode material, but the size and capacity can be increased. Not only is it difficult, but there is also the problem that it is not possible to find a cost advantage over the foil-type winding type aluminum electrolytic capacitor. On the other hand, in Patent Document 8, as a method for manufacturing an anode, it is proposed that a linear valve acting metal is continuously supplied and the surface thereof is roughened to form an oxide film. ..

Further, the material used for the electrode member is not related to the electrode member for the electrolytic capacitor but to the electric double layer capacitor current collector, but the following proposals have been made so far.

According to JP-A-2008-060124 (Patent Document 9), it is not possible to form irregularities sufficient to obtain the anchor effect of the electrode active material by physical roughening, and the equipment cost is high in AC etching. In the case of chemical etching, it is said that a large amount of Cu must be contained, but since Cu reduces corrosion resistance, it is corroded by the electrolytic solution in the electric double layer capacitor. There was a problem of inviting. On the other hand, Patent Document 9 proposes an aluminum foil for an electric double layer capacitor collector, which contains 50 to 500 ppm of Ni by mass ratio and has a composition of aluminum having a balance of 99% or more and unavoidable impurities. There is.

Japanese Unexamined Patent Publication No. 2008-07833 Japanese Unexamined Patent Publication No. 2-288217 Japanese Unexamined Patent Publication No. 2001-143972 Japanese Unexamined Patent Publication No. 3-104207 Japanese Unexamined Patent Publication No. 11-307400 Japanese Unexamined Patent Publication No. 2008-177199 Japanese Unexamined Patent Publication No. 2008-177200 Japanese Unexamined Patent Publication No. 61-278124 Japanese Unexamined Patent Publication No. 2008-060124

Patent Document 1 aims to improve the impregnation property at a position deeper than 20 μm from the surface. Specifically, a predetermined number of fine pits that greatly contribute to the capacitance are formed at a position deeper than 20 μm from the surface.

However, the impregnation property from the surface to a depth of 20 μm is not mentioned at all. Although there is a description that the pits are connected to each other near the surface to form an unnecessarily large pit, the specific size of the unnecessarily large pit diameter is not mentioned. From this, it is unclear whether or not the impregnation property from the surface to the position of the depth where the fine pits that greatly contribute to the capacitance are formed is also guaranteed.

Patent Document 2 is based on the findings found by the inventors of Patent Document 2 through experiments. Specifically, it is based on the finding that the conductive polymer film can be formed by chemical oxidative polymerization up to an average depth of 16 μm from the surface. In this Patent Document 2, only the tunnel-shaped pit is described in the drawing, as the capacity appearance rate is not so related to the shape of the pit. However, as described above, since the shape of the pit also contributes to the capacitance of the electrolytic capacitor, it is necessary to consider the shape of the pit in order to obtain a high capacitance appearance rate.

Patent Document 3 discloses a roughened layer in which recesses having different opening diameters are combined in order to increase the surface area of the electrode member. In particular, according to the drawings, the cross-sectional shapes of the dents are all substantially circular.

Further, both Patent Document 4 and Patent Document 5 disclose that a pit by AC etching is formed inside a tunnel-shaped pit by DC etching in order to increase the surface area of the electrode member. In particular, Patent Document 4 discloses a suitable range of the opening diameter of the tunnel-shaped pit.

However, the structures of the roughened layer / etching layer disclosed in Patent Documents 3 to 5 do not take into consideration the impregnation property of the solid electrolyte.

Since Patent Documents 1 to 5 relate to foil-shaped or plate-shaped electrode members, they also take into consideration the viewpoint of leakage current as a solid electrolytic capacitor, which may be a problem especially when the size is reduced. We have not yet provided a suitable electrode member for the above.

Patent Document 6 and Patent Document 7 disclose that a linear valve acting metal obtained by etching is used as an electrode member.

In Patent Document 6 and Patent Document 7, the capacity appearance rate is not mentioned at all. Further, regarding the etching performed on the aluminum wire, the specific processing method and the specific structure of the etching layer are not mentioned at all.

Patent Document 8 illustrates four types of circular, semi-circular, track-shaped, and quadrangular as an example of the cross-sectional shape of the linear valve-acting metal used for etching a linear valve-acting metal as an electrode member. ing.

However, since Patent Documents 6 to 8 do not disclose any specific structure of the etching layer, a suitable electrode member is provided from the viewpoint of capacity appearance rate and capacitance. Has not been reached. Further, Patent Document 8 does not take into consideration the influence of the difference in the cross-sectional shape of the linear valve acting metal.

In Patent Document 9, an aluminum foil containing 50 to 500 ppm of Ni and having a composition consisting of aluminum having a balance of 99% or more and unavoidable impurities is exclusively chemically etched. Moreover, the specific structure of the etching layer formed by chemical etching is not mentioned at all.

The present invention has been made in view of such problems, and is an electrode member for an electrolytic capacitor capable of sufficiently impregnating with an electrolyte and obtaining a high capacity appearance rate when manufacturing an electrolytic capacitor, and the electrolytic capacitor. It is an object of the present invention to provide an electrolytic capacitor provided with an electrode member for use.

The electrode member for an electrolytic capacitor based on the present invention is an electrode member for an electrolytic capacitor included in the electrolytic capacitor, the electrode member for the electrolytic capacitor has a wire shape, and the outer surface of the electrode member for the electrolytic capacitor has a wire shape. The opening diameter of the second recess, which includes at least one first recess that opens outward and at least one second recess that opens at least in the first recess, is represented by a circular equivalent diameter. It is smaller than the opening diameter of the first recess represented by the equivalent diameter. The electrode member for an electrolytic capacitor has a core portion and a porous layer located around the core portion. When the cross-sectional shape perpendicular to the axial direction of the electrolytic capacitor electrode member is viewed macroscopically, the peripheral edge of the cross-sectional shape is an annular shape having no angular portion. The first recess has a crater shape in which the depth from the opening surface to the bottom portion of the first recess is shorter than the maximum opening diameter of the opening surface of the first recess. The opening diameter of the first recess is larger than 5 μm and 50 μm or less. The depth of the first recess is 2 μm or more and 25 μm or less. The second recess has a crater shape in which the distance from the opening surface to the bottom portion of the second recess is shorter than the maximum opening diameter of the opening surface of the second recess. The outer surface further includes a fine third recess that opens into the second recess. The third recess has a substantially cube shape, a substantially regular triangular pyramid shape, or a substantially spherical shape.

The wire shape includes a linear shape, a rod shape, a wire shape, a fibrous shape, a string shape, a band shape, or an elongated pellet shape. The wire shape is preferably a shape including a short axis and a long axis when viewed from a direction orthogonal to the axial direction of the electrolytic capacitor electrode member, but the wire shape is the length in the length direction parallel to the axial direction. , The shape may be equal to the width in the width direction orthogonal to the length direction.

From a macroscopic point of view, when the cross-sectional shape perpendicular to the axial direction of the electrode member for the electrolytic capacitor is reduced, one end side and the other end side of the opening surface of the recess in the circumferential direction of the cross-sectional shape. By appearing to be connected in the circumferential direction, the reduction ratio at which the opening surface appears to be closed is shown, and preferably the maximum reduction ratio among the reduction ratios is shown.

The electrode member for an electrolytic capacitor based on the present invention is preferably made of an aluminum material containing 5 ppm or more and 150 ppm or less of Ni.

The electrolytic capacitor based on the present invention is between the electrolytic capacitor electrode member, the counter electrode member arranged so as to face the electrolytic capacitor electrode member, and the electrolytic capacitor electrode member and the counter electrode member. Equipped with an electrolyte placed in.

In the electrolytic capacitor based on the present invention, the electrolyte is preferably a solid electrolyte containing a conductive polymer.

When manufacturing an electrolytic capacitor, it is possible to provide an electrode member for an electrolytic capacitor capable of sufficiently impregnating with an electrolyte and obtaining a high capacity appearance rate, and an electrolytic capacitor provided with the electrode member for the electrolytic capacitor. ..

It is a perspective view schematically showing the first example of the base material which is the precursor of the electrode member for an electrolytic capacitor in this invention. It is a perspective view schematically showing the 2nd example of the base material which is the precursor of the electrode member for an electrolytic capacitor in this invention. It is a perspective view schematically showing the 3rd example of the base material which is the precursor of the electrode member for an electrolytic capacitor in this invention. It is a figure which shows an example of the cross-sectional shape when the base material which is the precursor of the electrode member for an electrolytic capacitor in this invention is cut perpendicular to the length direction. It is a figure which shows typically the 4th example of the base material which is the precursor of the electrode member for an electrolytic capacitor in this invention. It is an enlarged diagram schematically showing the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to one embodiment of the present invention is cut perpendicular to the length direction (axial direction). It is an enlarged diagram schematically showing the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the 1st modification of this invention is cut perpendicular to the length direction (axial direction). It is an enlarged diagram schematically showing the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the 2nd modification of this invention is cut perpendicular to the length direction (axial direction). It is an enlarged diagram schematically showing the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the 3rd modification of this invention is cut perpendicular to the length direction (axial direction). It is an enlarged diagram schematically showing the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the 4th modification of this invention is cut perpendicular to the length direction (axial direction). It is a photograph of a scanning electron microscope in which the surface layer of the electrode member for an electrolytic capacitor which concerns on Reference Example 1 was photographed from the direction perpendicular to the axial direction. It is a photograph of the scanning electron microscope which photographed the vicinity of the surface layer when the electrode member for an electrolytic capacitor which concerns on Reference Example 1 was cut perpendicular to the length direction (axial direction). In the electrode member for an electrolytic capacitor according to Reference Example 7, the vicinity of the surface layer was photographed after DC etching and before AC etching when the electrode member was cut perpendicular to the length direction (axial direction). It is a photograph of a scanning electron microscope. Scanning of the electrode member for an electrolytic capacitor according to Reference Example 7, in which the vicinity of the surface layer was photographed when the electrode member was cut perpendicular to the length direction (axial direction) in the state after performing AC etching after DC etching. It is a photograph of a scanning electron microscope. It is a figure which represented the conventional electrolytic capacitor schematically. It is a figure which schematically represented the degree of impregnation of a solid electrolyte in a conventional electrode member for an electrolytic capacitor.

Hereinafter, embodiments for carrying out the present invention will be described, but the following description is merely one of the embodiments of the present invention, and the present invention is not limited to these embodiments and is a gist thereof. It is possible to change and implement as appropriate within the range that does not change.

Further, in the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and the description thereof will not be repeated.

1. 1. Base material The base material 10 described below is a precursor of the electrode member 20 for an electrolytic capacitor (see FIG. 6 and the like) described later.

The electrode member 20 for an electrolytic capacitor can be manufactured by etching the base material 10 to form a porous portion 22 described later on the outer surface side of the base material 10. In this case, the base material 10 constitutes both the core portion 21 and the porous portion 22, which will be described later, included in the electrolytic capacitor electrode member 20.

Further, the electrode member 20 for an electrolytic capacitor can also be manufactured by forming the porous portion 22 around the base material 10 by vapor deposition, powder adhesion, or the like. In this case, the base material 10 constitutes the core portion 21.

FIG. 1 is a perspective view showing a first example of a base material which is a precursor of an electrode member for an electrolytic capacitor in the present invention. FIG. 2 is a perspective view schematically showing a second example of a base material which is a precursor of an electrode member for an electrolytic capacitor in the present invention. FIG. 3 is a perspective view schematically showing a third example of a base material which is a precursor of an electrode member for an electrolytic capacitor in the present invention. With reference to FIGS. 1 to 3, the shape of the base material which is the precursor of the electrode member for the electrolytic capacitor in the present invention will be described.

The base material 10 may have various shapes such as a linear shape, a rod shape, a wire shape, a fibrous shape, a string shape, a strip shape, and an elongated pellet shape. The base material 10 extends in a predetermined direction and has an axial direction.

The relationship between the length of the base material 10 in the length direction (axial direction) and the thickness of the base material 10 in the thickness direction orthogonal to the length direction is not particularly limited.

As shown in FIGS. 1 to 3, the base material 10 has, for example, a substantially cylindrical shape, and the cross-sectional shape perpendicular to the axial direction of the base material 10 has a substantially circular shape. As shown in FIG. 1, the relationship between the diameter φ ₁ indicating the thickness of the base material 10 and the length L ₁ may be φ ₁ <L ₁ . In this case, the base material 10 has an elongated shape. Further, as shown in FIG. 2, the relationship between the diameter φ ₁ indicating the thickness of the base material 10 and the length L ₁ may be φ ₁ = L ₁ . Further, as shown in FIG. 3, the relationship between the diameter φ ₁ indicating the thickness of the base material 10 and the length L ₁ may be φ ₁ > L ₁ . In this case, the base material 10 has a flat coin-like shape. The base material 10 preferably satisfies the relationship of φ ₁ <L ₁ . In this case, also in the electrolytic capacitor electrode member 20, the relationship between the diameter φ ₂ indicating the thickness of the electrolytic capacitor electrode member and the length L ₂ of the electrolytic capacitor electrode satisfies the relationship of φ ₂ <L ₂ . It becomes easy, and when the electrolytic capacitor is manufactured, the ratio of the surface area to the cross-sectional area becomes large, and it is possible to easily take the capacity. In addition, the leakage current can be further suppressed.

The cross-sectional shape perpendicular to the axial direction of the base material 10 is not limited to the circular shape. The cross-sectional shape of the base material 10 may be an oval shape such as an elliptical shape, an oval shape, a track shape, and an egg shape, or may be a peanut shape.

Further, it is preferable that the peripheral edge of the base material 10 having a cross-sectional shape perpendicular to the axial direction has an annular shape having no angular portion. The annular shape includes a polygonal shape with rounded corners, an oval shape, a peanut shape, and the like.

Since the peripheral edge of the cross-sectional shape perpendicular to the axial direction of the base material 10 has the above-mentioned shape, as will be described later, when the electrolytic capacitor is manufactured, the solid electrolyte is aligned with the surface of the electrode member 20 for the electrolytic capacitor. Is formed. As a result, the adhesion between the electrode member 20 for the electrolytic capacitor and the solid electrolyte is ensured, and a high capacity appearance rate can be obtained.

FIG. 4 is a diagram showing an example of a cross-sectional shape when a base material, which is a precursor of an electrode member for an electrolytic capacitor in the present invention, is cut perpendicular to the length direction thereof. An example of the cross-sectional shape of the base material 10 will be described with reference to FIG.

As shown in FIG. 4, the cross-sectional shape perpendicular to the axial direction of the base material 10 has, for example, a substantially triangular shape with rounded corners. Further, the base material 10 has a protrusion 11 protruding outward and a recess 12 denting inward.

The protrusion 11 has a curved portion 11a that curves along the protrusion direction DR1 toward the tip side on the root side. The curved portion 11a has a curved shape that is curved so as to be concave inward.

The recessed portion 12 has a curved portion 12a that curves along the recessed direction DR2 toward the bottom portion on the opening edge portion side. The curved portion 12a has a curved shape that is curved so as to be convex toward the outside.

As described above, even if the protrusions 11 and the recesses 12 are present, they have the curved portions 11a and the curved portions 12a as described above, so that when the electrolytic capacitor is manufactured, the electrode member 20 for the electrolytic capacitor 20 It is possible to secure the adhesion between the protrusions and dents in the solid electrolyte and the solid electrolyte. Thereby, even when the base material 10 has the protrusions 11 and the recesses 12, a high capacity appearance rate can be obtained.

The cross-sectional shape of the base material 10 when viewed perpendicularly to the length direction does not necessarily have to be constant along the length direction.

FIG. 5 is a diagram schematically showing a fourth example of a base material which is a precursor of an electrode member for an electrolytic capacitor in the present invention. Other shapes of the base material 10 will be described with reference to FIG.

As shown in FIG. 5, the end portion 10a of the base material 10 on one side in the length direction has a substantially triangular shape with rounded corners, and the end portion of the base material 10 on the other side in the length direction. Reference numeral 10b has a substantially quadrangular shape with rounded corners.

As described above, the base material 10 may have a shape different from the shape of the end portion 10a on one side in the length direction and the shape of the end portion 10b on the other side in the length direction. Also in this case, it is preferable that the cross-sectional shape at an arbitrary position along the length direction has an annular shape having no angular portion.

Further, one end portion 10a in the length direction and the other end portion 10b in the length direction are not necessarily limited to a planar shape, but may be formed by a curved surface shape or points. For example, the base material 10 may have an ellipsoidal shape such as a rugby ball whose surface is a quadric surface as an overall shape.

Further, as will be described later, when the base material 10 is etched to manufacture the electrode member 20 for an electrolytic capacitor, the shape of the base material 10 and the shape of the electrode member 20 for an electrolytic capacitor are substantially the same. However, it is preferable from the viewpoint of simplifying the electrolytic capacitor manufacturing process. In this case, the shapes of the base material 10 and the electrode member 20 for the electrolytic capacitor are the shapes when each of the base material 10 and the electrode member 20 for the electrolytic capacitor is viewed macroscopically, and the electrode member 20 for the electrolytic capacitor 20 Refers to the shape when observed at a scale ratio to the extent that the concave portion on the outer surface thereof cannot be seen.

As for the purity and impurities of the base material 10, the same base material as that used for the conventional electrode member for an electrolytic capacitor can be used in the present invention.

When the electrode member 20 for an electrolytic capacitor is manufactured using the base material 10, the first recesses 7a, 7b (see FIGS. 6, 7, etc.) and the second recesses 8a, 8b, 8c (FIG. 6, FIG. After forming (see FIGS. 8 and 10), the dielectric 2 is formed on the surface thereof. At this time, from the viewpoint of adhesion between the base material 10 and the dielectric 2, the dielectric 2 is preferably made of an oxide containing a metal component derived from the base material 10. Therefore, in the present invention, a substrate made of a valve acting metal such as aluminum, niobium, and tantalum is preferably used. More preferably, an aluminum material containing 5 ppm to 150 ppm of Ni is used, and more preferably, an aluminum material containing 20 ppm to 100 ppm of Ni is used as a base material.

As will be described later, when the concave portion is formed by etching, the dissolution of aluminum is promoted by adding Ni to the aluminum material, and it becomes easy to form a large concave portion on the surface layer of the electrode member 20 for an electrolytic capacitor. When the Ni content is 5 ppm to 150 ppm, particularly 20 ppm to 100 ppm, it is particularly suitable for forming a crater-like substance described later as the first recess.

This does not mean that the aluminum material containing 5 ppm to 150 ppm of Ni is not suitable for the base material when the tunnel-shaped one described later is formed as the first recess. The effect of adding Ni can be further obtained only for the purpose of forming a crater-like one as the first concave portion.

2. 2. Electrode member for electrolytic capacitor (1) Shape of electrode member for electrolytic capacitor FIGS. 6 to 10 are based on one embodiment of the present invention, a first modification, a second modification, a third modification, and a fourth modification. It is an enlarged diagram schematically showing the cross-sectional shape near the surface layer when the electrode member for an electrolytic capacitor is cut perpendicular to the length direction (axial direction).

As shown in FIGS. 6 to 10, the electrode member 20 for an electrolytic capacitor includes a core portion 21 and a porous portion 22 located around the core portion 21. When the electrode member 20 for an electrolytic capacitor is manufactured by etching the base material 10, the porous portion 22 is composed of a roughened portion of the base material 10.

The outer surface of the electrolytic capacitor electrode member 20 includes at least one first recess that opens outward and at least one second recess that opens into at least the first recess. The details of the recess will be described later.

As described above, when the electrode member 20 for an electrolytic capacitor is manufactured by etching the base material 10 to manufacture the electrode member 20 for an electrolytic capacitor, the shape of the base material 10 is substantially the same as the shape of the base material 10 when viewed macroscopically. Has a shape. Here, the macroscopic view refers to the shape when observed at a scale ratio such that the recesses on the outer surface of the electrolytic capacitor electrode member 20 cannot be seen.

Specifically, the electrode member 20 for an electrolytic capacitor has various shapes such as a linear shape, a rod shape, a wire shape, a fibrous shape, a string shape, a band shape, or an elongated pellet shape, like the base material 10. Further, as will be described later, the electrode member 20 for an electrolytic capacitor includes a base material 10 cut along a direction perpendicular to the axial direction, and may have various shapes cut. The various shapes and the shapes obtained by cutting the various shapes are collectively referred to as a wire shape. The electrode member 20 for an electrolytic capacitor has such a wire shape.

The wire shape is preferably a shape including a short axis and a long axis when viewed from a direction orthogonal to the axial direction of the base material 10, but the length in the length direction parallel to the axial direction and the said wire shape. The shape may be equal to the width in the width direction orthogonal to the length direction.

The relationship between the length of the electrode member 20 for an electrolytic capacitor in the length direction (axial direction) and the thickness of the electrode member 20 for an electrolytic capacitor in the thickness direction orthogonal to the length direction is particularly limited as in the base material 10. It is not something that will be done.

When viewed macroscopically, the electrode member 20 for an electrolytic capacitor may have, for example, a substantially cylindrical shape, and in this case, the cross-sectional shape perpendicular to the axial direction of the electrode member 20 for an electrolytic capacitor is a circle. It becomes a shape. In this case, the relationship between the diameter φ ₂ indicating the thickness of the electrolytic capacitor electrode member 20 and the length L ₂ may be φ ₂ <L ₂ or φ ₂ = L, as in the base material 10. It may be ₂ or φ ₂ > L ₂ .

The cross-sectional shape of the electrolytic capacitor electrode member 20 perpendicular to the axial direction is not limited to the circular shape. The cross-sectional shape of the electrode member 20 for an electrolytic capacitor may be an oval shape such as an elliptical shape, an oval shape, a track shape, an egg shape, or a peanut shape.

The peripheral edge of the electrode member 20 for an electrolytic capacitor having a cross-sectional shape perpendicular to the axial direction preferably has an annular shape having no angular portion when viewed macroscopically. The annular shape includes a polygonal shape with rounded corners, an oval shape, a peanut shape, and the like.

Manufacture an electrolytic capacitor using the electrode member 20 for an electrolytic capacitor, which has a cross-sectional shape perpendicular to the axial direction of the electrode member 20 for an electrolytic capacitor and has a corner that is not rounded at all such as a right angle. When a solid electrolyte such as a conductive polymer is used as the electrolyte, the area where the solid electrolyte can come into contact with the corners of the electrode member 20 for electrolytic capacitors that are not rounded at all, such as the right angle. Is very few.

Therefore, the adhesion between the solid electrolyte and the electrode member 20 for the electrolytic capacitor is poor at the corners of the electrode member 20 for the electrolytic capacitor that are not rounded at all, and the solid electrolyte is peeled off from the electrode member 20 for the electrolytic capacitor. In the first place, the solid electrolyte cannot be polymerized at the corners of the electrode member 20 for electrolytic capacitors that are not rounded at all, such as at right angles, which may lead to a decrease in the capacity appearance rate.

As in the embodiment, the peripheral edge of the cross-sectional shape of the electrode member 20 for an electrolytic capacitor perpendicular to the axial direction has an annular shape having no angular portion when viewed macroscopically, so that the electrode member 20 has an annular shape. A solid electrolyte is formed along the surface of the electrode member 20. As a result, the adhesion between the electrode member 20 for the electrolytic capacitor and the solid electrolyte is ensured, and a high capacity appearance rate can be obtained.

When the base material 10 has the protrusions 11 and / or the recesses 12 as described above, the electrode member 20 for the electrolytic capacitor also has the protrusions and / or the recesses. When the electrode member 20 for an electrolytic capacitor has a protrusion, similarly to the base material 10, the protrusion has a curved portion that curves along the protrusion direction toward the tip side on the root side, thereby forming the protrusion. Adhesion with the solid electrolyte can be ensured. Further, when the electrode member 20 for an electrolytic capacitor has a dent, similarly to the base material 10, it has a curved portion that curves along the dent direction toward the bottom, so that the dent and the solid electrolyte adhere to each other. Can be secured. Thereby, even when the electrode member 20 for an electrolytic capacitor has protrusions and / or dents, a high capacitance appearance rate can be obtained.

Further, the shape of the electrode member for the electrolytic capacitor in the present invention can be changed from the shape of the base material. For example, even if the shape of the base material is an elongated one having φ ₁ <L ₁ as shown in FIG. 1, it may be cut at the time of manufacturing the electrolytic capacitor to be used for the electrolytic capacitor as shown in FIG. The electrode for an electrolytic capacitor in the present invention also has a shape like a flat coin in which the relationship between the diameter φ ₂ indicating the thickness of the electrode member and the length L ₂ of the electrode for the electrolytic capacitor is φ ₂ > L ₂ . Included in the member. The electrode member for the electrolytic capacitor preferably satisfies the relationship of φ ₂ <L ₂ . In this case, the ratio of the surface area to the cross-sectional area becomes large, and it is possible to easily take the capacity. In addition, the leakage current can be further suppressed.

When the electrode member 20 for an electrolytic capacitor is manufactured by etching the base material 10, the dissolution of aluminum is promoted by adding Ni to the aluminum material, so that the surface layer of the electrode member 20 for an electrolytic capacitor is large. It becomes easy to form a recess. Therefore, it is preferable that the electrode member 20 for the electrolytic capacitor also contains Ni, and the Ni content of the electrode member 20 for the electrolytic capacitor is preferably 5 ppm to 150 ppm, and particularly suitable is 20 ppm to 100 ppm. That is, the electrode member 20 for an electrolytic capacitor is preferably made of an aluminum material containing 5 ppm or more and 150 ppm or less of Ni, and more preferably made of an aluminum material containing 20 ppm or more and 100 ppm or less of Ni.
(2) Overall Structure of Recesses The electrode member 20 for an electrolytic capacitor in the present invention includes at least one first recess having an outer surface of at least one, and at least one second recess having an outer surface that opens into at least the first recess. Therefore, a wire-shaped base material is used. The first recess is a recess that opens toward the outside of the electrolytic capacitor electrode member 20, and is compared with a recess formed at a position deep (for example, the core side) from the surface layer of the electrolytic capacitor electrode member 20. And say something big. Further, the electrode member 20 for an electrolytic capacitor in the present invention includes a member in which a third concave portion finer than the second concave portion is formed. Hereinafter, an example thereof will be described with reference to FIGS. 6 to 10.

FIG. 6 is an enlarged schematic representation of the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the embodiment of the present invention is cut perpendicular to the length direction thereof.

As shown in FIG. 6, in the electrode member of one embodiment, the outer surface of the electrode member 20 for an electrolytic capacitor includes a first recess 7b and a second recess 8a.

The first recess 7b is open toward the outside of the electrolytic capacitor electrode member 20, and has an opening surface 7d. The first recess 7b has a tunnel shape. In the first recess 7b, the depth from the opening surface 7d to the bottom 7b1 of the first recess 7b is longer than the maximum opening diameter of the opening surface 7d.

The first recess 7b extends toward the axis. Specifically, for example, the first recess 7b extends along a direction perpendicular to the axial direction. The extending direction of the first recess 7b is not limited to the direction perpendicular to the axial direction, and may extend in any direction having a twisting relationship with the axial direction.

The second recess 8a mainly opens to the first recess 7b and has an opening surface 8d. A part of the second recess 8a is open toward the outside of the electrolytic capacitor electrode member 20. The opening diameter of the second recess 8a represented by the diameter equivalent to a circle is smaller than the opening diameter of the first recess 7b represented by the diameter equivalent to a circle.

The second recess 8a has a substantially cube shape. The shape of the second recess 8a is not limited to a substantially cube shape, and may be a substantially regular triangular pyramid shape, a substantially spherical shape, or the like. Here, the substantially cube shape, the substantially regular triangular pyramid shape, and the substantially spherical shape are not necessarily limited to those that geometrically satisfy the requirements of the cubic shape, the regular triangular pyramid shape, and the spherical shape, and the width and the height from the requirements. , It is acceptable that the depth ratio deviates to some extent.

FIG. 7 is an enlarged schematic representation of the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the first modification of the present invention is cut perpendicular to the length direction thereof.

As shown in FIG. 7, an example of the electrode member 20 for an electrolytic capacitor in the first modification is outside the electrode member 20 for an electrolytic capacitor when compared with the electrode member 20 for an electrolytic capacitor according to the embodiment shown in FIG. Of the first recess 7a and the second recess 8a included in the surface, the shape of the first recess 7a is different. Other configurations are almost the same.

The first recess 7a has a crater shape. In the first recess 7a, the depth from the opening surface 7d to the bottom 7a1 of the first recess 7a is shorter than the maximum opening diameter of the opening surface 7d.

The second recess 8a is mainly open to the first recess 7a and has a substantially cube shape. A part of the second recess 8a is open to the outside. The opening diameter of the second recess 8a represented by the diameter equivalent to a circle is smaller than the opening diameter of the first recess 7a represented by the diameter equivalent to a circle.

FIG. 8 is an enlarged schematic representation of the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the second modification of the present invention is cut perpendicular to the length direction thereof.

As shown in FIG. 8, an example of the electrolytic capacitor electrode member 20 in the second modification is outside the electrolytic capacitor electrode member 20 when compared with the electrolytic capacitor electrode member 20 according to the embodiment shown in FIG. The shapes of both the first recess 7a and the second recess 8b included in the surface are different.

The first recess 7a has a crater shape. In the first recess 7a, the depth from the opening surface 7d to the bottom 7a1 of the first recess 7a is shorter than the maximum opening diameter of the opening surface 7d.

The second recess 8b is mainly open to the first recess 7a and has a substantially tunnel shape. A part of the second recess 8b is open to the outside. In the second recess 8b, the depth from the opening surface 8d to the bottom 8b1 of the second recess 8b is longer than the maximum opening diameter of the opening surface 8d. The opening diameter of the second recess 8b represented by the diameter equivalent to a circle is smaller than the opening diameter of the first recess 7a represented by the diameter equivalent to a circle.

FIG. 9 is an enlarged and schematically representation of the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the third modification of the present invention is cut perpendicular to the length direction thereof.

As shown in FIG. 9, an example of the electrode member 20 for an electrolytic capacitor in the third modification has an outer surface of the base material 10 as compared with the electrode member 20 for an electrolytic capacitor in the second modification shown in FIG. It differs in that it further includes a third recess 9.

The third recess 9 is mainly open to the second recess 8b and has, for example, a substantially cube shape. The shape of the third recess 9 is not limited to a substantially cube shape, and may be a substantially regular triangular pyramid shape, a substantially spherical shape, or the like. The third recess 9 is more finely configured than the second recess 8b. The opening diameter of the third recess 9 represented by the diameter equivalent to a circle is smaller than the opening diameter of the second recess 8b represented by the equivalent circle.

FIG. 10 is an enlarged schematic representation of the cross-sectional shape in the vicinity of the surface layer when the electrode member for an electrolytic capacitor according to the fourth modification of the present invention is cut perpendicular to the length direction thereof.

As shown in FIG. 10, the electrode member 20 for an electrolytic capacitor according to the fourth modification is mainly different in the shape of the second recess 8c when compared with the electrode member 20 for an electrolytic capacitor in the third modification.

The first recess 7a has a crater shape. The first recess 7a has a larger opening diameter corresponding to a circle when compared with the first recess 7a in the third modification.

The second recess 8c is mainly open to the first recess 7a and has a crater shape. A part of the second recess 8c may be open to the outside. In the second recess 8c, the depth from the opening surface 8d to the bottom 8c1 of the second recess 8c is shorter than the maximum opening diameter of the opening surface 8d.

The third recess 9 is mainly open to the second recess 8c and has a substantially cube shape. A part of the third recess 9 is open to the outside. The third recess 9 is more finely configured than the second recess 8b. The opening diameter of the third recess 9 represented by the diameter equivalent to a circle is smaller than the opening diameter of the second recess 8b represented by the equivalent circle.

Considering that the thickness of the dielectric formed on the surface of the electrode member 20 for the electrolytic capacitor changes according to the working voltage of the electrolytic capacitor, the second recess as shown in FIGS. 6 and 7 is provided. The electrolytic capacitor electrode member 20 according to the embodiment having a substantially cube shape or a substantially spherical shape, the electrolytic capacitor electrode member 20 according to the first modification, and the third recess as shown in FIGS. 9 and 10 are provided. The electrolytic capacitor electrode member 20 according to the third modification and the electrolytic capacitor electrode member 20 according to the fourth modification are suitable for those having a relatively low working voltage.

On the other hand, as shown in FIG. 8, the electrode member 20 for an electrolytic capacitor according to a second modification in which the second recess is tunnel-shaped and the third recess having a substantially cube shape or a substantially spherical shape is not formed is If anything, it is suitable for those with a relatively high working voltage.
(3) First recess Since the second recess is finer than the first recess, it greatly contributes to the expansion of the surface area of the electrolytic capacitor electrode member 20. Here, since the second recess has a substantially cube shape, when the second recess communicates in a state of being displaced in a predetermined direction, a portion that is partially narrowed in the communication direction is generated.

Therefore, when a solid electrolyte such as a conductive polymer is used as the electrolyte, the electrolyte is placed in a portion where a plurality of fine recesses communicate with the fine recesses (for example, the opening diameter is less than 1 μm) that open toward the outside. In the case of impregnation, the fine recesses at a certain depth from the surface layer are closed with the electrolyte, and the fine recesses at a deeper position are not impregnated with the electrolyte. In this case, the capacity appearance rate decreases.

Therefore, as in the present invention, a first concave portion having an opening to the outside and a larger opening diameter than the second concave portion is provided, and the second concave portion is opened in the first concave portion, thereby corresponding to the depth of the first concave portion. Therefore, the impregnation property in the vicinity of the surface layer of the electrode member 20 for the electrolytic capacitor can be ensured. Further, the electrolyte impregnated in the first recess enters the second recess that opens in the first recess, and the second recess is sufficiently filled. As a result, a high capacity appearance rate can be obtained.

The first recesses preferably have an opening diameter of 1 μm to 500 μm and / or a depth of 0.5 μm to 250 μm, 1 piece / mm ² to 2.0 × 10 ⁵ pieces / mm ² . It exists in density.

When a solid electrolyte such as a conductive polymer is used as the electrolyte, the opening diameter of the first recess is set to 1 μm or more, more preferably 3 μm or more in view of the particle size of the solid electrolyte, so that the electrolyte is contained in the first recess. Can be filled. Along with this, the electrolyte can be sufficiently filled in the second recess that opens in the first recess. The second recess can also be formed with an appropriate density by setting the thickness to 500 μm or less, more preferably 20 μm or less.

Further, by providing the second recess so as to open in the first recess, when a plurality of fine second recesses are formed without providing the first recess, the portion where the second recess is dense is formed from the surface layer of the base material 10. It is possible to suppress peeling. As a result, the second recess can be formed with an appropriate density.

Further, preferably, the depth of the first recess is 0.5 μm to 250 μm. Further, more preferably, the depth of the first recess is 1.5 μm to 10 μm.

As described above, the portion where the second recess and the second recess are connected is often a portion where a part of the second recess and a part of the second recess overlap. Since the second recess is fine, the portion where the second recess and the second recess adjacent to the second recess are connected becomes finer. Therefore, in the case where only a plurality of fine recesses (for example, having an opening diameter of less than 1 μm) are provided so as to open to the outside without providing the first recess, and the fine recesses are impregnated with the electrolyte, the fine recesses are impregnated. It is easy for the electrolyte to block the part where the fine recesses are connected and the electrolyte cannot be impregnated into the fine recesses located deeper than that. ..

Therefore, by providing the second recess so as to open in the first recess larger than the second recess, the impregnation property of the electrolyte can be improved by the amount corresponding to the depth of the first recess.

On the other hand, if the depth of the first recess is too large, it becomes difficult to form fine recesses having a sufficient density, which greatly contributes to the expansion of the surface area of the electrode member 20 for the electrolytic capacitor.

Therefore, by setting the depth of the first recess to 0.5 μm to 250 μm, more preferably 1.5 μm to 10 μm, both the capacity appearance rate and the capacitance can be improved.

Further, the density of the first recess is set to 1 piece / mm ² to 2.0 × 10 ⁵ pieces / mm ² , more preferably 3 × 10 ² pieces / mm ² to 150 × 10 ² pieces / mm ² . The second recess, which greatly contributes to the surface area of the electrode member 20 for the electrolytic capacitor, can be formed with an appropriate density. As a result, it is possible to prevent the portion where the second recesses are densely separated from the surface layer of the base material 10.

Further, by providing the second recess in each of the first recesses formed at the above density, not only in each of the first recesses, but also in the electrode member 20 for the electrolytic capacitor as a whole, the second recess is 10,000. The electrolyte can be filled evenly.

From the above, regarding the first recess, when the first opening diameter is 1 μm to 500 μm and the density is 1 piece / mm ² to 2.0 × 10 ⁵ pieces / mm ² , the first recess is formed. The second recess to be opened can be sufficiently filled with the electrolyte, and the second recess can be evenly filled with the electrolyte when viewed as a whole of the electrode member 20 for the electrolytic capacitor. Therefore, when the electrode member 20 for an electrolytic capacitor is used, a higher capacity appearance rate can be obtained.
(4) Second recess The second recess is finer than the first recess, and contributes significantly to the surface area of the electrolytic capacitor electrode member 20. Therefore, the second recess formed on the inner wall of the first recess further forms a second recess on the inner wall thereof, particularly when the shape is substantially cube-shaped or substantially spherical, and this is repeated to form the second recess. By connecting the above, the surface area of the electrode member 20 for the electrolytic capacitor can be increased, and a high capacitance can be obtained.

The second recess is not necessarily limited to the one formed on the inner wall of the first recess and the one connected to the inner wall. The second recess includes one that opens toward the outside of the electrolytic capacitor electrode member 20 and is smaller than the first recess, particularly one having an opening diameter of less than 1 μm and one connected to the first recess.

An anchor effect is obtained by allowing the solid electrolyte to enter the one that opens to the outside of the electrode member 20 for the electrolytic capacitor and the one that is formed near the surface layer of the electrode member 20 for the electrolytic capacitor, so that the electrode member 20 for the electrolytic capacitor and the solid are obtained. The adhesion of the electrolyte can be increased. As a result, it is possible to prevent a decrease in the capacitance appearance rate due to the solid electrolyte being separated from the electrode member 20 for the electrolytic capacitor.

Further, since the second recess is connected in multiple layers in the direction opposite to the first recess, the surface area of the electrode member 20 for the electrolytic capacitor (more accurately, for the electrolytic capacitor to which the electrolyte can come into contact). The surface area of the dielectric formed on the electrode member 20) becomes large, and a high capacitance can be obtained.

Further, as shown in FIG. 10, there is also a crater-shaped second recess 8c that is larger than the third recess 9 but smaller than the first recess 7a. That is, the second recess in the present invention also includes a recess that is continuous from the inner wall of the first recess in a direction opposite to that of the first recess while reducing its size.

It should be noted that "while reducing the size" does not necessarily mean only the case where the size is continuously reduced. It is sufficient that the opening diameter corresponding to the circle of the second recess on the deepest side is smaller than the opening diameter corresponding to the circle of the second recess in the portion opened in the first recess, and the deepest from the first opening side. A portion larger than the opening diameter corresponding to the circle of the second recess in the portion opened in the first recess may be included before reaching the portion side.

By forming a structure in which a plurality of crater-shaped first recesses and crater-shaped second recesses that contribute to impregnation are connected in this way, the electrolyte can be impregnated deeper. Further, by providing the second concave portion 8c whose diameter is once expanded and reduced from the opening side to the deepest portion side of the concave portion as described above, the second concave portion 8c is provided so that the opening diameter extends in the depth direction in a constant state. The surface area of the electrode member 20 for an electrolytic capacitor can be increased as compared with the case where a recess is provided.

Preferably, the opening diameter of the second concave portion when expressed in terms of the equivalent circle diameter is 50 nm to 1 μm.

Generally, when a solid electrolyte layer such as a conductive polymer is used as an electrolyte to form a solid electrolyte layer, chemical oxidation polymerization or electrolytic polymerization has been conventionally performed. However, in both chemical oxidative polymerization and electrolytic polymerization, the polymerization solution directly reacts with the electrode member 20 for an electrolytic capacitor during the polymerization. As a result, chemical stress is applied to the electrode member 20 for the electrolytic capacitor, and sufficient characteristics cannot be obtained particularly in a region where the withstand voltage is high.

Therefore, in recent years, a solid electrolyte layer has also been formed by a method of applying a dispersion solution and drying it. When such a dispersion solution is used, since no chemical stress is applied to the electrode member 20 for the electrolytic capacitor, sufficient characteristics can be obtained even in a place where the withstand voltage is high, and there is an advantage that the manufacturing process is simplified. .. However, unlike the polymer solution, the dispersion solution merely disperses the conductive polymer, so that the particle size of the conductive polymer becomes a problem.

Therefore, in order to effectively form the solid electrolyte layer by the method using the dispersion solution, the opening diameter of the second recess is 50 nm or more as in the present embodiment in view of the particle size of the solid electrolyte. Is preferable.

On the other hand, since the second recess contributes to the expansion of the surface area of the electrode member 20 for the electrolytic capacitor, the opening diameter is set to 1 μm or less, and the upper limit is set in the gap portion per second recess to increase the amount. The second recess can be formed.
(5) Third Recessed As an example of the electrode member 20 for an electrolytic capacitor in which a substantially cube-shaped or substantially spherical third recess is formed, for example, as shown in FIG. 9, a crater-shaped first recess and a tunnel-shaped first recess are formed. There is an electrode member 20 for an electrolytic capacitor according to a third modification in which two recesses are formed.

Since the finest third recess is substantially cube-shaped or substantially spherical, the electrode member 20 for an electrolytic capacitor in this case is suitable for an electrolytic capacitor having a relatively low working voltage. In order to increase the surface area of the electrode member 20 for an electrolytic capacitor, fine third recesses are connected in multiple layers. However, when a plurality of third recesses communicate with the third recess that opens to the outside, the third recess and the third recess are formed in the same manner as in the case where the shape of the second recess is substantially cube-shaped or substantially spherical. It is easy for the electrolyte to block the connected portion so that the electrolyte cannot be impregnated up to the third recess located deeper than the concave portion.

On the other hand, when the first concave portion is crater-shaped, if the depth of the crater is made too deep, it becomes impossible to form a fine concave portion that contributes to the surface area by that amount.

Therefore, the capacitance appearance rate near the surface layer of the electrolytic capacitor electrode member 20 is improved by forming a crater-shaped first recess, and the capacitance appearance rate at a position relatively deep from the surface layer of the electrolytic capacitor electrode member 20 is tunnel-shaped. It is improved by forming the second concave portion of. On top of that, the capacitance is increased by forming a third recess that contributes to the expansion of the surface area of the electrode member 20 for the electrolytic capacitor. By forming three types of recesses such as a first recess, a second recess, and a third recess, the above effects can be obtained.

As a fourth modification, as described above, the electrode member 20 for an electrolytic capacitor in which both the first recess 7a and the second recess 8c are crater-shaped is shown in FIG. 10, but with the third modification as shown in FIG. Similarly, the first recess 7a and the second recess 8c contribute to the improvement of impregnation property, whereas the third recess 9 contributes to the expansion of the surface area of the electrode member 20 for the electrolytic capacitor. It is a thing.
(6) Method for Forming Recesses As a method for forming recesses such as the first recess, the second recess, and the third recess of the electrode member 20 for an electrolytic capacitor in the present invention, for example, etching (direct current, alternating current, chemical, sputtering, plasma, etc.) ), Vapor deposition and powder adhesion (including those that have been sintered after adhesion).

In the case of etching, when the first recess, the second recess and the third recess are formed by separate steps, for example, DC etching in an aqueous solution containing hydrochloric acid (for example, a tunnel-shaped first recess and a second recess). (When forming), AC etching (for example, when forming a crater-shaped first recess and second recess, lower the frequency to form fine substantially cube-shaped or substantially spherical second recesses and third recesses. If it is formed, the frequency is increased) or chemical etching (for example, if the first concave portion is formed, it has a hole having the same size as the target first concave portion as a pretreatment for chemical etching). Masking) can be selected according to the shape of each recess.

When performing AC etching, the frequency is gradually increased. Specifically, when the first recess and the second recess are formed, the frequency is changed in two stages. For example, in the first stage, AC etching is performed at 0.2 to 7 Hz, preferably 0.2 to 6 Hz, and in the second stage, AC etching is performed at 3 to 120 Hz, preferably 4 to 60 Hz. However, it is assumed that the frequency is set higher in the second stage than in the first stage. Further, when the first recess, the second recess and the third recess are formed, the frequency is changed in three stages. For example, in the first stage, AC etching is performed at 0.2 to 7 Hz, preferably 0.2 to 6 Hz, in the second stage, AC etching is performed at 1 to 20 Hz, preferably 2 to 15 Hz, and in the third stage, AC etching is performed. AC etching is performed at 3 to 120 Hz, preferably 4 to 60 Hz. However, it is assumed that the frequency is set higher in the second stage than in the first stage, and in the third stage than in the second stage. Before forming the first recess, alkali treatment or acid treatment may be performed for the purpose of degreasing the surface of the base material.

Also, for example, even if the size of each pit formed by etching is small, they may be combined to form one large pit, or a part of the base material existing while they are connected in a row may be present. Large pits may be formed by detaching from the main body of the base material. Therefore, also in the electrode member 20 for an electrolytic capacitor in the present invention, each pit formed by etching in an aqueous solution containing hydrochloric acid has the same size as the second recess, but the second recess is formed on the surface layer of the base material. As a result of the combination of the second recess and the second recess, a first recess larger than the second recess can be formed together with the second recess.

Such a forming method is particularly preferable when the shape of the first recess is crater-shaped, but it can also be performed by any of DC etching, AC etching and chemical etching.

Similarly, in the case of forming up to the third recess, the first recess and the second recess may be formed as a result of the combination of the third recess and the third recess on the surface layer of the base material. Those having recesses are also included in the electrode member 20 for an electrolytic capacitor in the present invention.

It should be noted that it is not necessary to carry out under the same conditions all the time during the formation of the recesses, and it is also possible to appropriately change the conditions according to the progress of the formation of the recesses in the manufacture of the electrode member 20 for an electrolytic capacitor according to the present invention. Included in the method. Further, when changing the conditions, for example, performing a step other than etching that does not directly form a recess between AC etching and AC etching is also a method for manufacturing the electrode member 20 for an electrolytic capacitor in the present invention. included.

Further, when the electrode member 20 for an electrolytic capacitor in the present invention is formed by such a method, the dissolution of aluminum is promoted by adding Ni. Therefore, it is preferable to use an aluminum material containing 5 ppm to 150 ppm of Ni as the base material.

In addition to etching in an aqueous solution containing hydrochloric acid, physical methods such as sputtering etching in which ions collide with the surface of the substrate and plasma etching using an electron beam, and mechanical methods such as blasting in which small particles collide with each other. Also included in the method for manufacturing the electrode member 20 for an electrolytic capacitor in the present invention.

In the case of vapor deposition and powder adhesion (including sintering), for example, vapor-deposited particles and powder (including sinterable particles) are densely arranged in the vicinity of the surface layer of the base material so as to reduce voids. When the vapor-deposited layer or powder-adhered layer (including the sintered layer) approaches the desired thickness, multiple types of sizes can be obtained by changing the conditions so that those with large voids coexist. Different recesses can be formed.

From the viewpoint of simplifying the electrolytic capacitor manufacturing process, etching is preferable to vapor deposition and powder adhesion (including sintering), and etching in an aqueous solution containing hydrochloric acid is preferable.

3. 3. Electrolytic capacitor The electrolytic capacitor in the present invention is between the electrolytic capacitor electrode member, a counter electrode member arranged so as to face the electrolytic capacitor electrode member, and the electrolytic capacitor electrode member and the counter electrode member. Equipped with an electrolyte placed in. Preferably, the electrolyte is a solid electrolyte containing a conductive polymer.

Specifically, the electrolytic capacitor in the present invention has substantially the same configuration as the electrolytic capacitor shown in FIG. 15 except that the electrode member for the electrolytic capacitor according to the present embodiment is used as the anode body.

More specifically, the electrolyte is sandwiched between the anode, the dielectric formed on the anode, the electrolyte arranged adjacent to the dielectric on the opposite side of the anode, and the anode. It is provided with a cathode body as a counter electrode member arranged so as to face the anode body 1 in this manner.
(1) Dielectric When the electrode member 20 for an electrolytic capacitor in the present invention is used as an anode body, a dielectric film is formed on the surface thereof. Examples of the method include anodizing in an aqueous solution of ammonium borate, ammonium phosphate, ammonium adipate and the like.
(2) Electrolyte There are two types of electrolytic capacitors, one in which the electrolyte is liquid (driving electrolyte) and the other in which the electrolyte is solid (solid electrolyte), and the electrode member 20 for the electrolytic capacitor in the present invention is of any type. It can also be used for electrolytic capacitors. In the electrolytic capacitor of the present invention, both the driving electrolyte and the solid electrolyte can be those conventionally used for the electrolytic capacitor.

For example, in the driving electrolyte, polyethylene glycol, γ-butyrolactone and the like are used as solvents, and polypyrrole, polythiophene, polyfuran, polyaniline, and derivatives thereof are examples of the conductive polymer among the solid electrolytes. Be done.
(3) Cathode body When the electrode member 20 for an electrolytic capacitor in the present invention is used as an anode body, the cathode body is electrolyzed when the electrolyte is a driving electrolytic solution and the anode body is formed in a foil shape. A cathode foil having the same configuration as the cathode used for the capacitor can be used. On the other hand, when the electrolyte is a solid electrolyte, as the cathode body, a cathode foil can be used in the same manner as when a driving electrolyte is used, or for example, a laminate of a carbon layer and a silver paste layer can be used. ..
(4) Other main materials of electrolytic capacitors The separator sandwiched between the anode and the cathode body, the anode terminal connected to the anode body, the cathode terminal connected to the cathode body, the aluminum case and the sealing rubber have been conventionally used for the electrolytic capacitor. Can be used.
(5) Method for Manufacturing an Electrolytic Capacitor An example of the manufacturing method will be described with respect to a case where the electrode member 20 for an electrolytic capacitor in the present invention is used as an anode and a driving electrolytic solution is used as an electrolyte.

A dielectric is formed on the surface of the anode by anodization, and the anode terminal is connected to the anode on which the dielectric is formed by laser welding or the like. A separator and a cathode foil to which a cathode terminal is connected are sequentially wound around an anode having a dielectric formed on its surface. The anode and cathode foil after winding are impregnated with a driving electrolyte as an electrolyte. The anode and cathode foil impregnated with the driving electrolyte are housed in an aluminum case, and the opening of the aluminum case is sealed with a sealing rubber.

In the case where the electrode member 20 for an electrolytic capacitor in the present invention is used as an anode and a solid electrolyte is used as the electrolyte, another example of the manufacturing method thereof will be described.

A dielectric is formed on the surface of the anode by anodization, and the anode terminal is connected to the anode on which the dielectric is formed by laser welding or the like. A cathode foil to which a separator and a cathode terminal are connected is sequentially wound around an anode having a dielectric formed on its surface.

Next, a conductive polymer layer as a solid electrolyte is formed between the wound anode and the cathode foil. The conductive polymer layer is chemically oxidatively polymerized by alternately applying a reaction solution consisting of a monomer which is a precursor of the polymer, a dopant, and an oxidizing agent to carry out a polymerization reaction, or electrochemically polymerizing in the reaction solution. It can be formed by electrolytic polymerization in which a reaction is carried out, or a method in which a solution in which a conductive polymer having previously developed conductivity is dissolved or dispersed in an arbitrary solvent is applied. In addition, a conductive polymer can also be formed by combining these methods.

As an example of the combination, in consideration of the chemical stress applied to the electrode member 20 for the electrolytic capacitor, first, a layer is formed by a method using a dispersion solution, and then chemical oxidation polymerization or electrolytic polymerization is performed. As the dispersion solution, for example, a poly (3,4-ethylenedioxythiophene) dispersion is commercially available. Then, the anode body and the cathode foil on which the conductive polymer is formed are housed in an aluminum case, and the opening of the aluminum case is sealed with a sealing rubber.

In addition, an example of another manufacturing method will be described. A dielectric is formed on the surface of the anode by anodization. Next, in order to provide a cathode portion on one end side of the anode body so as to cover the anode body, an insulating band is formed in a portion between one end side and the other end side of the anode body. As a result, the anode is divided into a cathode portion forming region in which the cathode portion is formed on one end side and an anode portion exposed portion exposed on the other end side.

Examples of the method for forming the insulating band include a method for forming an insulator inside the surface layer and the surface area expanding layer of the base material, a method for removing the surface area expanding layer, and the like for forming the insulating band.

Next, in the cathode portion forming region, a solid electrolyte layer is formed on the dielectric, and then a carbon layer and a silver paste layer are sequentially formed on the solid electrolyte layer. The cathode portion is formed by the carbon layer and the silver paste layer.

Next, the cathode terminal is connected to the silver paste layer with a conductive adhesive or the like. Further, the exposed portion of the anode body is connected to the anode terminal. Examples of the terminal material include metal pieces, metal lead materials, printed wiring board patterns, etc., and can be connected by laser welding, resistance welding, ultrasonic welding, etc., and conductive resin or conductive adhesive. It is also possible to use an agent, metal plating, etc. as each terminal material.

Then, it is molded with a sealing material containing a resin. In the case of another example of the manufacturing method, the electrolytic capacitor in the present invention also has an anode body arranged in parallel via a cathode body composed of a carbon layer and a silver paste layer, and a plurality of the anode bodies stacked in parallel. include.

4. Evaluation method (1) Structure of the first recess and the second recess The surface layer of the electrode member 20 for an electrolytic capacitor in which the first recess and the second recess are formed is observed with a scanning electron microscope or a microscope to acquire an image. do.

If necessary, the acquired image is binarized using image analysis software, and then the equivalent circle diameter of each concave portion in the observation field is obtained. The number of recesses in the range of 0.5 μm to 250 μm and the number of other recesses are calculated and converted per mm ² .

The electrode member 20 for an electrolytic capacitor in which the first recess and the second recess are formed is cut perpendicular to the length direction thereof, and the cross section near the surface layer at that time is observed with a scanning electron microscope. The opening diameter in this cross-sectional photograph is not necessarily circular, but the depth of the recess in which the opening diameter represented by the equivalent circle diameter is in the range of approximately 0.5 μm to 250 μm is measured.
(2) Capacitance and capacity appearance rate With an LCR meter with a measurement frequency of 120 Hz, the capacitance of the electrode member 20 for an electrolytic capacitor before being immersed in a solution of a conductive polymer is used for anodic oxidation. The measurement is carried out in an aqueous solution of ammonium adipate or an aqueous solution of ammonium borate, depending on the aqueous solution. Then, the capacitance of the manufactured capacitor is measured with an LCR meter having a measurement frequency of 120 Hz. The capacitance appearance rate is obtained from the capacitance of the electrode member 20 for an electrolytic capacitor in an aqueous solution and the capacitance of the capacitor.
(3) Leakage current Measure the current value after applying the rated voltage to the solid electrolytic capacitor for 1 minute. The leakage current is obtained from the following equation 1.

Leakage current = current value after applying the rated voltage for 1 minute (μA) / (capacitance (μF) / rated voltage (V) of the capacitor measured at 120 Hz) ... (Equation 1)

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to the examples.

(Reference example 1)
(1) The following materials were used as the base material in the state before the recesses were formed.
(I) Shape: A columnar shape having a circular cross-sectional shape perpendicular to the length direction.
(II) Component: Aluminum material having a purity of 99.99% and containing no Ni.
(III) Diameter: 0.2 mm.
(IV) Length: 1.0 mm.
(2) After performing acid treatment for the purpose of degreasing the surface of the substrate, recesses are formed in an aqueous solution containing 4.5 wt% hydrochloric acid, 0.9 wt% sulfuric acid and 2.0 wt% aluminum chloride. AC etching was performed under the conditions of current density: 280 mA / cm ² and current waveform (half wave): triangular wave so that the thickness of the existing layer was about 65 μm. The frequency was changed in two steps, and was set to 1 Hz in the front stage and 60 Hz in the rear stage, respectively. The liquid temperature was set to 45 ° C. in the front stage and 35 ° C. in the rear stage, respectively. After the AC etching was completed, an acid treatment was performed for the purpose of removing chloride ions. As a result, the electrode member 20 (anode body) for the electrolytic capacitor was prepared.
(3) A voltage of 3 V was applied to the electrolytic capacitor electrode member 20 in an aqueous solution of ammonium adipate to anodize the electrolytic capacitor electrode member 20.
(4) The separator and the cathode foil for the electrolytic capacitor were sequentially wound around the electrode member 20 for the electrolytic capacitor on which the dielectric (oxide film) was formed by anodizing.
(5) The electrode member 20 for the electrolytic capacitor and the cathode foil after winding are manufactured by SIGMA-ALDRICH, which is commercially available, and PEDOT / PSS 1.0 wt. % In _H2O , high-condivity grade Orgacon® (registered trademark) HIL-1005 (Product No .: 768642) and dried. This was repeated a desired number of times to form a solid electrolyte layer between the electrode member 20 for the electrolytic capacitor and the cathode foil.
(6) The electrode member 20 for an electrolytic capacitor and the cathode foil on which the solid electrolyte layer was formed were housed in an aluminum case, and the opening of the aluminum case was sealed with a sealing rubber.

(Example 2)
The frequency of AC etching was changed in 3 steps, except that the front stage was set to 1 Hz, the middle stage was set to 10 Hz, and the rear stage was set to 60 Hz, respectively, and the liquid temperature was set to 45 ° C in the front stage, 45 ° C in the middle stage, and 35 ° C in the rear stage, respectively. Made an electrode member 20 for an electrolytic capacitor and an electrolytic capacitor in the same manner as in Reference Example 1.

(Example 3)
The frequency of the AC etching was changed in three stages, but the electrode member 20 for the electrolytic capacitor was the same as in Example 2 except that the first frequency was set to 0.2 Hz, which is one-fifth of Reference Example 1. And made an electrolytic capacitor.

(Reference example 4)
The frequency of the AC etching was changed in three stages, but the electrode member 20 for the electrolytic capacitor and the electrolytic capacitor were used in the same manner as in Example 2 except that the first frequency was set to 5 Hz, which is five times that of Reference Example 1. Made.

(Reference example 5)
Except for using a prismatic substrate with a square cross-sectional shape perpendicular to the length direction and a side length of 0.16 mm as the substrate in the state before the recess is formed. , The electrode member 20 for the electrolytic capacitor and the electrolytic capacitor were manufactured in the same manner as in Example 2.

(Example 6)
An electrode member 20 for an electrolytic capacitor and an electrolytic capacitor were produced in the same manner as in Example 2 except that an aluminum material having a purity of 99.99% containing 50 ppm of Ni was used as the base material.

(Comparative Example 1)
An electrode member 20 for an electrolytic capacitor and an electrolytic capacitor were manufactured in the same manner as in Reference Example 1 except that the frequency of AC etching was fixed at 60 Hz and the liquid temperature was fixed at 45 ° C.

(Reference example 7)
(1) The following materials were used as the base material in the state before forming the recesses.
(I) Shape: A columnar shape having a circular cross-sectional shape perpendicular to the length direction.
(II) Component: Aluminum material having a purity of 99.99% and containing no Ni.
(III) Diameter: 0.8 mm.
(IV) Length: 3.0 mm.
(2) After performing acid treatment for the purpose of degreasing the surface of the substrate, the current density is 50 mA / cm ² and the amount of electricity is in an aqueous solution containing 1.8 wt% hydrochloric acid, 23 wt% sulfuric acid and 15 wt% aluminum sulfate. DC etching was performed under the conditions of 3 C / cm ² and a liquid temperature of 72 ° C. Further, for the purpose of enlarging the tunnel-shaped first recess formed by DC etching, chemical etching was performed for 10 minutes at a liquid temperature of 75 ° C. in an aqueous solution containing 1.0 wt% nitric acid and 12 wt% aluminum nitrate. .. Then, in an aqueous solution containing 4.5 wt% hydrochloric acid, 0.9 wt% sulfuric acid and 2.0 wt% aluminum chloride, the liquid temperature: 35 ° C., the current density: 280 mA / cm ² , the frequency: 60 Hz, and the current waveform (half). Wave): AC etching was performed under the condition of triangular wave. After performing AC etching, acid treatment was performed for the purpose of removing chloride ions. As a result, the electrode member 20 for the electrolytic capacitor was prepared.
(3) A voltage of 200 V was applied to the electrolytic capacitor electrode member 20 in an aqueous ammonium borate solution to anodize the electrolytic capacitor electrode member 20.
(4) The separator and the cathode foil for the electrolytic capacitor were sequentially wound around the electrode member 20 for the electrolytic capacitor on which the dielectric (oxide film) was formed by anodizing.
(5) The electrode member 20 for the electrolytic capacitor and the cathode foil after winding are manufactured by SIGMA-ALDRICH, which is commercially available, and PEDOT / PSS 1.0 wt. % In _H2O , high-condivity grade Orgacon® (registered trademark) HIL-1005 (Product No .: 768642) and dried. This was repeated a desired number of times to form a solid electrolyte layer between the electrode member 20 for the electrolytic capacitor and the cathode foil.
(6) The electrode member 20 for an electrolytic capacitor and the cathode foil on which the solid electrolyte layer was formed were housed in an aluminum case, and the opening of the aluminum case was sealed with a sealing rubber.

(Comparative Example 2)
An electrode member 20 for an electrolytic capacitor and an electrolytic capacitor were manufactured in the same manner as in Reference Example 7, except that only AC etching was performed without performing DC etching and chemical etching.

For Reference Examples 1, 4-5, 7, Examples 2-3, 6 and Comparative Examples 1 to 2, the structure of the recess is shown in Table 1, and the electrode member for the electrolytic capacitor after anodic oxidation and before immersion in the conductive polymer solution. Table 2 shows the capacitance, the capacitance appearance rate, and the leakage current of the capacitor in the 20 aqueous solutions.

For each unit in Table 1, the opening diameter and depth are "μm", and the density is "x10 ³ pieces / mm ² ".

Regarding the capacitance in Table 2, Reference Examples 1, 4-5 and Examples 2-3 and 6 are values when the value of Comparative Example 1 is 100, and Reference Example 7 is a value of Comparative Example 2. Is set to 100. The capacity appearance rate is "%". The leakage current is "μA / (μF · V)".

When the surface layer of the electrode member 20 for an electrolytic capacitor before the anodizing treatment of Reference Example 1 was observed with a scanning electron microscope from a direction perpendicular to the axial direction, a photograph as shown in FIG. 11 was obtained. On the surface layer of the electrode member 20 for an electrolytic capacitor, a large number of crater-shaped first recesses 7a having an opening diameter on the order of about 5 μm to about 10 μm were formed. Further, the inner wall of the crater-shaped first recess 7a was uneven. That is, a large number of second recesses opened in the inner wall of the crater-shaped first recess 7a were formed. Further, the surface layer of the electrode member 20 for the electrolytic capacitor was formed with recesses on the order of about 5 μm to about 10 μm. That is, a second recess that opens to the outside was also formed on the surface layer of the electrode member 20 for the electrolytic capacitor.

When the electrode member 20 for an electrolytic capacitor before the anodizing treatment of Reference Example 1 was cut perpendicular to the length direction, the cross section near the surface layer was observed with a scanning electron microscope, and a photograph as shown in FIG. 12 was observed. was gotten. In Reference Example 1, a crater-shaped first recess 7a having an opening diameter on the order of about 10 μm is formed in the vicinity of the surface layer of the electrode member 20 for an electrolytic capacitor, and a large number of recesses 8a smaller than the crater-shaped first recess 7a are formed. Was there.

In Reference Example 7, the vicinity of the surface layer of the electrode member 20 for an electrolytic capacitor when cut perpendicular to the length direction of the electrode member 20 after DC etching and before AC etching was observed with a scanning electron microscope. However, a photograph as shown in FIG. 13 was obtained. In Reference Example 7, a crater-shaped first recess 7a having an opening diameter on the order of about 10 μm is formed in the vicinity of the surface layer of the electrode member 20 for an electrolytic capacitor, and a tunnel-shaped first recess 7a having an opening diameter on the order of about 2 μm is formed. The formation of the second recess 8b was observed.

In Reference Example 7, the vicinity of the surface layer when the electrode member 20 for an electrolytic capacitor, which has undergone AC etching in addition to DC etching, is cut perpendicular to its length direction is observed with a scanning electron microscope. As a result, a photograph as shown in FIG. 14 was obtained. A crater-shaped first recess 7a having an opening diameter on the order of about 10 μm and a tunnel-shaped second recess 8b having an opening diameter on the order of about 2 μm were formed in the vicinity of the surface layer of the electrode member 20 for an electrolytic capacitor. .. In addition, a third recess 9 finer than the second recess 8b is formed on the inner wall of the tunnel-shaped second recess 8b and the inner wall of the crater-shaped first recess 7a, and a third recess opening to the outside is formed. It had been.

Comparing Reference Examples 1, 4-5, and Examples 2-3 and 6 with Comparative Example 1, and Reference Example 7 and Comparative Example 2, the leakage current is suppressed in each of the examples as compared with the comparative example. At the same time, the capacity appearance rate was high. Here, the difference between the examples and the comparative examples is whether or not the first recesses are formed, and the fine recesses are formed in substantially the same manner in the examples and the comparative examples. Therefore, from these comparisons, leakage current is suppressed by including the first recess having a large opening diameter different from the minute recess in the surface layer of the electrode member 20 for the electrolytic capacitor, regardless of the working voltage of the electrolytic capacitor. However, it can be said that it was experimentally confirmed that the capacity appearance rate could be improved.

Comparing Reference Example 1 and Example 2, Example 2 has a higher capacity appearance rate. Therefore, rather than forming a fine recess on the inner wall of the crater-shaped first recess that exclusively contributes to the expansion of the surface area of the electrolytic capacitor electrode member 20, a crater-shaped second recess smaller than the first recess is first formed. However, it was confirmed that a higher capacity appearance rate can be obtained by forming finer recesses.

It can be seen that the capacity appearance rates are substantially the same between Examples 2-3 and Reference Example 4. Therefore, it was confirmed that the same capacity appearance rate can be obtained when the opening diameter of the first recess is 1 μm to 50 μm and the depth of the first recess is 0.5 μm to 25 μm.

Comparing Example 2 and Reference Example 5, the capacity appearance rate is higher in Example 2. By the way, in both Example 2 and Reference Example 5, the cross-sectional shape perpendicular to the length direction of the electrode member 20 for the electrolytic capacitor when viewed macroscopically is perpendicular to the length direction of the base material. It has the same cross-sectional shape. The cross-sectional shape of the base material in Example 2 is circular, and the cross-sectional shape of the base material in Reference Example 5 is square. Then, when viewed macroscopically, in Example 2, the cross-sectional shape of the electrolytic capacitor electrode member 20 becomes circular, and in Reference Example 5, the cross-sectional shape of the electrolytic capacitor electrode member 20 becomes square. Therefore, it was confirmed that a circular shape has a higher capacity appearance rate than a square shape with corners. That is, when viewed macroscopically, it was confirmed that a higher capacitance appearance rate can be obtained by having the cross-sectional shape of the electrode member 20 for the electrolytic capacitor in the axial direction having an annular shape having no angular portion. rice field.

In both Example 2 and Example 6, the first recess is crater-shaped, but the opening diameter and depth thereof are larger in Example 6. Therefore, when forming the crater-shaped first recess, it was confirmed that it is easier to form by using a base material intentionally containing Ni.

In Comparative Example 1 and Comparative Example 2, other conditions were almost the same as those in the example, and when the frequency of AC etching was fixed, the leakage current became large, but the frequency of AC etching was changed. Even when fixed, by appropriately changing the current density, temperature, composition of the aqueous solution, etc. to form the first recess and the second recess as described in the embodiment, the capacity is the same as in the embodiment. Leakage current can be suppressed while improving the appearance rate.

Although the embodiments and examples of the present invention have been described above, the embodiments and examples disclosed this time are exemplary in all respects and are not limiting. The scope of the present invention is indicated by the scope of claims and includes all modifications within the meaning and scope equivalent to the scope of claims.

INDUSTRIAL APPLICABILITY The present invention can be used for manufacturing an electrolytic capacitor, particularly a solid electrolytic capacitor, which requires a high capacity appearance rate. The electrolytic capacitor manufactured by the present invention is not particularly limited in its application and can be used, for example, as a filter for attenuating noise.

1 Anode, 2 Dielectric, 3 Electrolyte, 4 Dielectric, 5 Cathode, 6 Solid Electrolyte, 7a, 7b 1st Recess, 8a, 8b, 8c 2nd Recess, 9 3rd Recess, 10 Substrate, 11 Protrusion , 11a curved part, 12 dent, 12a curved part, 20 electrode member for electrolytic capacitor, 21 core part, 22 porous part.

Claims (4)

An electrode member for an electrolytic capacitor included in an electrolytic capacitor.
The electrode member for an electrolytic capacitor has a wire shape and has a wire shape.
The outer surface of the electrode member for an electrolytic capacitor includes at least one first recess that opens outward and at least one second recess that opens into at least the first recess.
The opening diameter of the second recess represented by the diameter equivalent to a circle is smaller than the opening diameter of the first recess represented by the diameter equivalent to a circle.
The electrode member for an electrolytic capacitor has a core portion and a porous layer located around the core portion.
When the cross-sectional shape perpendicular to the axial direction of the electrode member for the electrolytic capacitor is viewed macroscopically, the peripheral edge of the cross-sectional shape is an annular shape having no angular portion.
The first recess has a crater shape in which the depth from the opening surface to the bottom portion of the first recess is shorter than the maximum opening diameter of the opening surface of the first recess.
The opening diameter of the first recess is larger than 5 μm and 50 μm or less.
The depth of the first recess is 2 μm or more and 25 μm or less.
The second recess has a crater shape in which the distance from the opening surface to the bottom portion of the second recess is shorter than the maximum opening diameter of the opening surface of the second recess.
The outer surface further includes a fine third recess that opens into the second recess.
The third recess is an electrode member for an electrolytic capacitor having a substantially cube shape, a substantially regular triangular pyramid shape, or a substantially spherical shape. The electrode member for an electrolytic capacitor according to claim 1, which is made of an aluminum material containing 5 ppm or more and 150 ppm or less of Ni. The electrode member for an electrolytic capacitor according to claim 1 or 2,
A counter electrode member arranged so as to face the electrolytic capacitor electrode member,
An electrolytic capacitor including an electrolyte arranged between the electrode member for an electrolytic capacitor and the counter electrode member. The electrolytic capacitor according to claim 3, wherein the electrolyte is a solid electrolyte containing a conductive polymer.

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