JP2003213302A - Niobium powder, niobium sintered compact, and capacitor using niobium sintered compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor having an increased capacity per unit mass, reduced leakage current and high moisture resistance, to provide a sintered compact used as an electrode material for the capacitor and giving high capacity appearance ratio, to provide niobium powder for a raw material for the sintered compact and has excellent workflow characteristics at compaction and easy to perform continuous compaction and stably producing the capacitor, and to provide methods for manufacturing them. <P>SOLUTION: The niobium sintered compact which has pore distribution having a pore-diameter peak top within the range of 0.01 to 500 μm and preferably having a plurality of pore-diameter peak tops is used as a capacitor electrode to constitute the capacitor. It is preferable that the capacitor-anode sintered compact and the capacitor are constituted by using the niobium powder having (0.5 to 2.5) g/ml tapping density, 10 to 1,000 μm average particle diameter, 10 to 60° angle of repose and (0.5 to 40) m<SP>2</SP>/g BET specific surface area. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a niobium powder and a sintered body capable of stably producing a capacitor having a large capacity per unit mass and excellent leakage current characteristics and moisture resistance.
The present invention relates to a capacitor using these and a manufacturing method thereof.

[0002]

2. Description of the Related Art Capacitors used in electronic equipment such as mobile phones and personal computers are desired to be small in size and large in capacity. Among these capacitors, tantalum capacitors are preferred because they have a large capacity for their size and good performance. Further, recent electronic devices are required to operate at low voltage, operate at high frequency, and have low noise, and even for solid electrolytic capacitors, lower ESR (equivalent series resistance) is required.

A sintered body of tantalum powder is generally used as an anode body of a tantalum capacitor. The powder is molded and then sintered to be integrated into an electrode called a sintered body. The inside of the sintered body has a three-dimensional complex shape in which the powder is electrically and mechanically connected. After forming a dielectric film layer on the surface of the sintered body including the surfaces of the internal voids, a material to be the counter electrode is impregnated to form a capacitor. The capacity of the manufactured capacitor is largely dependent on the contact state between the counter electrode material and the dielectric coating layer, as long as the dielectric coating layer is uniformly attached to the surface inside the sintered body.

In order to increase the capacity of these tantalum capacitors, it is necessary to increase the mass of the sintered body or use a sintered body in which tantalum powder is pulverized to increase the surface area. The method of increasing the mass of the sintered body inevitably increases the shape of the capacitor and does not satisfy the demand for miniaturization. On the other hand, in the method of pulverizing tantalum powder to increase the specific surface area, the pore diameter of the tantalum sintered body becomes small,
In addition, the number of closed holes increases at the sintering stage, which makes it difficult to impregnate the catholyte in the subsequent process. For example, when a phosphoric acid aqueous solution is used as the counter electrode material, assuming that the contact state with the dielectric coating layer layer is perfect and the capacity appearance rate (also referred to as the cathodic agent impregnation rate) at that time is 100%, an electrode with a large viscosity When a material, especially a solid electrode material is used, the capacity appearance rate is 10
It was difficult to set it to 0%. Especially, when the average particle size of the tantalum powder is small, or when the shape of the sintered body made from the tantalum powder is large, the difficulty increases, and in an extreme case, the capacity appearance rate is less than 50%. There were things. Further, in the case of such a low capacity appearance rate, it was not possible to obtain sufficient moisture resistance of the manufactured capacitor. In addition, when the tantalum powder for producing the tantalum sintered body has a small pore size, the sintered body inevitably has a small pore size and the capacity appearance rate decreases. As a result, there arises a problem that the ESR cannot be lowered.

As one of means for solving these drawbacks, an electrode material having a dielectric constant larger than that of tantalum is used, and a sintered body having a high capacity appearance rate is produced, and this is used as an electrode. A capacitor is possible.

As such an electrode material that can be industrially supplied, niobium, which has a larger dielectric constant and a larger buried amount than tantalum, is known.

In JP-A-55-157226, niobium fine powder having a particle size of 2.0 μm or less is pressure-molded from agglomerated powder and sintered, and the molded sintered body is finely cut. , A method of manufacturing a sintered element for a capacitor in which a lead portion is joined to the lead portion and then sintered again. However, the publication does not provide details on the characteristics of the capacitor.

US Pat. No. 4,084,965 discloses that
4. Niobium ingot was hydrogenated and crushed to have an average particle size of 5.
A capacitor obtained by obtaining 1 μm niobium powder and sintering this is disclosed. However, the disclosed capacitor has a large leakage current (hereinafter sometimes abbreviated as LC) value and is not practical.

Japanese Unexamined Patent Publication No. 10-242004 discloses that the LC value is improved by, for example, nitriding a part of niobium powder.

The tapping density of the niobium powder for capacitors is an important factor in the molding operation of the niobium powder. For the conventional ones, the tapping density is 2.5 g /
It was larger than ml and about 4 g / ml, which was not sufficient for molding.

That is, when such a niobium powder is molded and sintered to form a sintered body, the flow of the niobium powder from the molding machine hopper to the mold is poor, and a fixed amount of niobium powder is constantly weighed to obtain the metal. It was difficult to put in a mold. For this reason, the shape of the molded body is not always sufficiently stabilized, the strength of the molded body and the sintered body is insufficient, and as a result, capacitors having poor LC are produced frequently. In addition, if a special molding apparatus that can handle powder having poor flowability is used, the molding cost becomes too high, which is not practical.

For this reason, the conventionally known niobium powder for capacitors is not sufficiently adaptable to continuous molding, and there is a problem that the productivity of capacitors is low.

[0013]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a capacitor having a large capacity per unit mass and a small leakage current value and a capacitor having high moisture resistance, and a sintered body which can be used as an electrode material and has a high capacity appearance rate. Another object of the present invention is to provide a niobium powder which is preferable as this sintered body material, has good flowability during molding, is easy to continuously mold, and allows stable production of capacitors, and a manufacturing method thereof.

[0014]

[Means for Solving the Problems] The present inventors diligently studied the aforementioned problems. As a result, when a niobium sinter having a specific pore distribution, preferably a niobium sinter having a plurality of pore diameter peak tops is used for a capacitor electrode, a high capacity appearance rate can be obtained. It was found that a capacitor with low leakage current and good moisture resistance can be produced. Furthermore, the tapping density is preferably 0.5 to
2.5 g / ml, more preferably 10 to 10
It has been found that 1000 μm niobium powder has good flowability, can be continuously molded, and is preferable as the material for the sintered body, and that when this niobium powder is used, a capacitor having a low leakage current value can be stably produced. These have been found and the present invention has been completed. More preferably, a niobium sintered body prepared by using niobium powder having a wide pore distribution, a plurality of pore diameter peak tops, and all of the pore diameter peak tops being 0.5 μm or more is used for a capacitor electrode. It was found that a low ESR can be achieved with a high capacity appearance rate.

That is, the present invention relates to the following niobium powder, niobium sintered body, capacitors using the same, and their manufacturing methods. (1) Niobium powder for capacitors having a tapping density of 0.5 to 2.5 g / ml. (2) The niobium powder according to item 1, which has an average particle diameter of 10 to 1000 μm. (3) The niobium powder as described in 1 or 2 above, which has an angle of repose of 10 to 60 degrees. (4) The niobium powder according to any one of items 1 to 3 above, which has a BET specific surface area of 0.5 to 40 m 2 / g. (5) The niobium powder according to any one of the above items 1 to 4, which has a pore distribution having a pore diameter peak top in the range of 0.01 μm to 500 μm. (6) The niobium powder according to item 5, wherein the pore distribution has a plurality of pore diameter peak tops. (7) All pore diameter peak tops are 0.5 μm to 1
7. The niobium powder according to any one of items 5 to 6 above, which is in the range of 00 μm. (8) The content of at least one element selected from the group consisting of elements of nitrogen, carbon, boron and sulfur is 200,
Any one of the above 1 to 7, which is 000 mass ppm or less
The niobium powder according to item.

(9) A sintered body using the niobium powder according to any one of items 1 to 8 above. (10) The sintered body according to the above item 9, which has a pore distribution having a pore diameter peak top within a range of 0.01 μm to 500 μm. (11) A niobium sintered body for a capacitor electrode, wherein the pore distribution of the niobium sintered body has a plurality of pore diameter peak tops. (12) The niobium sintered body according to item 11, wherein the pore distribution is composed of two pore diameter peak tops. (13) Among the plurality of pore diameter peak tops, the peak tops of the two peaks having the highest relative intensities are in the ranges of 0.2 to 0.7 μm and 0.7 to 3 μm, respectively, and described in the above item 11 or 12. Niobium sintered body. (14) Among the plurality of pore diameter peak tops, the peak top of the peak having the largest relative intensity is located on the larger diameter side than the peak top of the peak having the next largest relative intensity. The niobium sintered body described. (15) The niobium sintered body according to the above items 9 to 14, wherein the sintered body has a volume of 10 mm3 or more including the pore void volume. (16) The niobium sintered body according to the above items 9 to 15, wherein the sintered body has a specific surface area of 0.2 to 7 m2 / g. (17) A part of the sintered body is nitrided, as described in 9 to 16 above.
The niobium sintered body according to 1. (18) 4000 when the sintered body is sintered at 1300 ° C
18. The niobium sintered body according to any one of items 12 to 17, which is a sintered body obtained from a niobium compact that gives a sintered body having a CV value of 0 to 200,000 μFV / g.

(19) A capacitor comprising the niobium sintered body according to any one of the above items 9 to 18 as one electrode and a dielectric material interposed between the electrode and the counter electrode. (20) The capacitor as described in 19 above, wherein the main component of the dielectric is niobium oxide. (21) The capacitor according to the above item 19, wherein the counter electrode is at least one material selected from the group consisting of an electrolytic solution, an organic semiconductor and an inorganic semiconductor. (22) The counter electrode is an organic semiconductor, and the organic semiconductor is composed of a benzopyrroline tetramer and chloranil, an organic semiconductor containing tetrathiotetracene as a main component, and a tetracyanoquinodimethane as a main component. 22. The capacitor according to item 21, which is at least one material selected from the group consisting of an organic semiconductor and a conductive polymer. (23) The capacitor according to the above item 22, wherein the conductive polymer is at least one selected from polypyrrole, polythiophene, polyaniline and substituted derivatives thereof. (24) The conductive polymer is the following general formula (1) or general formula (2)

[0018]

[Chemical 3]

(Wherein R 1 to R 4 are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 10 carbon atoms, an alkoxy group or an alkyl ester group, or a halogen atom, Nitro group, cyano group, primary, secondary or tertiary amino group, CF3 group,
It represents a monovalent group selected from the group consisting of a phenyl group and a substituted phenyl group. The hydrocarbon chains of R1 and R2 and R3 and R4 may be attached to each other at any position to form a saturated or unsaturated hydrocarbon of at least one or more 3-7 membered ring with the carbon atom being substituted by such groups. You may form the bivalent chain which forms a cyclic structure. The cyclic bond chain may contain a bond of carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl and imino at any position. X represents an oxygen, sulfur or nitrogen atom, R5 is present only when X is a nitrogen atom, and independently represents hydrogen or a linear or branched saturated or unsaturated alkyl group having 1 to 10 carbon atoms. Represent 23. The capacitor according to item 22 above, which is a conductive polymer obtained by doping a polymer containing a repeating unit represented by) with a dopant. (25) The conductive polymer is represented by the following general formula (3)

[0020]

[Chemical 4]

(In the formula, R 6 and R 7 are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or the alkyl group is at any position relative to each other. It represents a substituent that forms a cyclic structure of a saturated hydrocarbon of at least one or more 5 to 7-membered ring containing two oxygen elements, and a vinylene bond which may be substituted in the cyclic structure. And a phenylene structure which may be substituted) are included in the conductive polymer.
Capacitor described in. (26) The capacitor according to the above item 22, wherein the conductive polymer is a conductive polymer obtained by doping poly (3,4-ethylenedioxythiophene) with a dopant. (27) The capacitor according to the above item 19, wherein the counter electrode is made of a material having a layered structure in at least a part thereof. (28) The capacitor according to the above item 19, wherein the counter electrode is a material containing an organic sulfonate anion as a dopant.

(29) The method for producing niobium powder according to any one of the above items 1 to 8, wherein the niobium or niobium compound is activated. (30) The activation treatment of niobium or a niobium compound is at least 1 selected from the group consisting of a sintering step and a crushing step.
30. The method for producing niobium powder as described in 29 above, which is carried out in various steps. (31) The method for producing niobium powder as described in (29) or (30) above, wherein the activation treatment of niobium or a niobium compound is performed using a mixture containing niobium or a niobium compound and an activator. (32) The average particle size of niobium or a niobium compound is
32. The method for producing niobium powder according to any one of the above items 29 to 31, which is 0.01 μm to 10 μm. (33) The niobium according to any one of the above items 29 to 32, wherein the niobium or the niobium compound contains at least one element selected from the group consisting of nitrogen, carbon, boron and sulfur in an amount of 200,000 ppm or less. Powder manufacturing method. (34) The method for producing niobium powder according to any one of the above items 29 to 33, wherein the niobium compound is at least one selected from the group consisting of niobium hydride, niobium alloys and hydrogenated niobium alloys. (35) The alloy components other than niobium of the niobium alloy and the hydrogenated niobium alloy are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine, niobium, helium, from the group consisting of elements having an atomic number of 88 or less. 35. The method for producing niobium powder according to the above item 34, which is at least one element selected from the group excluding neon, argon, krypton, xenon, and radon.

(36) The method for producing niobium powder as recited in the aforementioned Item 31, wherein a mixture containing niobium or a niobium compound and an activator is mixed using a solvent. (37) The solvent is at least one solvent selected from the group consisting of water, alcohols, ethers, cellosolves, ketones, aliphatic hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons. 37. The method for producing niobium powder as described in 36 above. (38) The method for producing niobium powder as described in the above item 31, wherein the activator is used in an amount of 1 to 40 mass% with respect to the total amount of niobium or the niobium compound. (39) The method for producing niobium powder as described in the above item 31 or 38, wherein the activator has an average particle size of 0.01 to 500 μm. (40) The method for producing niobium powder according to any one of the above items 31, 38, and 39, wherein the activator has a plurality of particle size peak tops. (41) The method for producing niobium powder according to any one of the above items 31 to 40, wherein the activator is a substance that is removed as a gas at 2000 ° C. or lower. (42) The activator is naphthalene, anthracene, quinone, camphor, polyacrylic acid, polyacrylic ester,
Polyacrylamide, polymethacrylic acid, polymethacrylic acid ester, polymethacrylamide, polyvinyl alcohol, NH4Cl, ZnO, WO2, SnO2, MnO3
41. which is at least one selected from the group consisting of
The method for producing the niobium powder according to 1. (43) The activator is a water-soluble substance, an organic solvent-soluble substance,
An acidic solution-soluble substance, an alkaline solution-soluble substance, a substance which forms a complex into these soluble substances, and 2000
41. The method for producing niobium powder according to any one of the above items 31 to 40, which is at least one selected from the group consisting of these substances that become soluble substances at a temperature of not more than 0 ° C. (44) The activator is a metal, carbonic acid, sulfuric acid, sulfurous acid, halogen, perhalogen acid, hypohalogen acid, nitric acid, nitrous acid,
44. The method for producing niobium powder according to the above item 43, which is at least one selected from the group consisting of a compound with phosphoric acid or boric acid, a metal, a metal hydroxide, and a metal oxide. (45) The activator is lithium, sodium, potassium,
Rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium,
Radium, scandium, yttrium, cerium, neodymium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, manganese, rhenium, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, silver, gold, Zinc, cadmium, boron, aluminum, gallium, indium, thallium, silicon, germanium, tin, lead, arsenic, antimony, bismuth, selenium, tellurium, polonium, and at least one selected from the group consisting of these compounds. 43. The method for producing niobium powder according to item 43.

(46) Any one of the above items 29 to 42, wherein the activation treatment is a treatment of removing the activator by heating and / or depressurizing before or during the sintering step.
The method for producing the niobium powder according to the item. (47) The activation treatment is carried out by bringing a solvent into contact with the sintered product or the crushed product after the sintering process, during the crushing process, or after the crushing process,
29 to 40, which is a treatment for removing the activator component
The method for producing the niobium powder according to any one of 3 to 45. (48) The method for producing niobium powder according to item 47, wherein the solvent is at least one selected from the group consisting of water, an organic solvent, an acidic solution, an alkaline solution, and a solution containing a ligand forming a soluble complex. . (49) The method for producing niobium powder according to item 48, wherein the acidic solution is at least one solution selected from the group consisting of nitric acid, sulfuric acid, hydrofluoric acid, and hydrochloric acid. (50) The method for producing niobium powder according to the item 48, wherein the alkaline solution contains at least one selected from the group consisting of alkali metal hydroxides and ammonia. (51) The ligand is at least one selected from the group consisting of ammonia, glycine, and ethylenediaminetetraacetic acid.
49. The method for producing the niobium powder according to item 48, which is a seed. (52) The method for producing niobium powder as described in 48 above, wherein the organic solvent is methyl isobutyl ketone.

(53) The niobium powder according to any one of items 1 to 7 above is treated by at least one method selected from the group consisting of liquid nitriding, ion nitriding, and gas nitriding. A method for producing niobium powder containing nitrogen. (54) A carbon containing the niobium powder according to any one of the above items 1 to 7 treated by at least one method selected from the group consisting of solid-phase carbonization and liquid carbonization. Manufacturing method of niobium powder. (55) Boron, characterized in that the niobium powder according to any one of items 1 to 7 above is treated by at least one method selected from the group consisting of gas boration and solid phase boration. Of producing niobium powder containing. (56) The niobium powder according to any one of items 1 to 7 above is treated by at least one method selected from the group consisting of gas sulfide, ion sulfide, and solid phase sulfide. A method for producing a niobium powder containing sulfur. (57) A niobium powder obtained by the method according to any one of the above items 29 to 56. (58) A method for producing a niobium sintered body, which comprises using the niobium powder according to any one of the above items 1 to 8 and 57.

(59) The niobium sintered body is used as one electrode,
A method for manufacturing a capacitor including a dielectric formed on the surface of the sintered body and a counter electrode provided on the dielectric, wherein the niobium sintered body is any one of the above 1 to 8 and 57. A method for producing a capacitor, which is obtained by sintering the niobium powder according to item 1. (60) The method for manufacturing a capacitor according to claim 59, wherein the dielectric is formed by electrolytic oxidation. (61) A method of manufacturing a capacitor including a niobium sintered body as one electrode, a dielectric formed on the surface of the sintered body, and a counter electrode provided on the dielectric, the method comprising: niobium sintering 19. A method of manufacturing a capacitor, wherein the body is the niobium sintered body according to any one of items 9 to 18 above.

(62) An electronic circuit using the capacitor described in any one of the above items 19 to 28. (63) An electronic device using the capacitor according to any one of items 19 to 28 above.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a capacitor having excellent leakage current characteristics and moisture resistance, a niobium sintered body capable of obtaining the characteristics thereof and having a high capacity appearance rate, a preferable flowability as a material of this sintered body, and continuous molding The niobium powder capable of being manufactured and the manufacturing method thereof will be described.

In the present invention, as the niobium powder satisfying the characteristics of the capacitor and improving the productivity in manufacturing the capacitor, niobium powder for capacitors having a tapping density of 0.5 to 2.5 g / ml (simply niobium). (Sometimes abbreviated as powder) is used. Here, niobium for a capacitor means a material containing niobium as a main component and which can be a material for manufacturing a capacitor. This may include, for example, components capable of alloying with niobium, components other than niobium such as nitrogen and / or oxygen.

Oval powder for capacitors is molded and sintered by the following method to obtain a sintered body for capacitors (sometimes abbreviated as niobium sintered body), on which a dielectric layer and a counter electrode are formed. And a capacitor can be obtained.

A niobium powder for capacitors is put into a solution in which a binder (described later) is dissolved in an organic solvent such as toluene or methanol, and this is thoroughly mixed using a shaking mixer, a V-type mixer or the like. Then, using a dryer such as a conical dryer, the organic solvent is distilled off under reduced pressure,
A niobium compound powder containing a binder is prepared. This compounded powder is put into an automatic molding machine hopper. The niobium mixed powder is weighed by flowing the introduction pipe from the hopper into the molding machine die and automatically dropping into the die, and is molded together with the lead wire.
After removing the binder from the molded body under reduced pressure, 500
A niobium sintered body is produced by sintering at a temperature of ℃ to 2000 ℃. Then, for example, the niobium sintered body is subjected to chemical conversion treatment for 1 to 30 hours under pressure of 20 to 60 V in an electrolytic solution of phosphoric acid, adipic acid or the like at a temperature of 30 to 90 ° C. and a concentration of about 0.1% by mass, and oxidation. A dielectric layer based on niobium is created. On this dielectric layer, a solid electrolyte layer of manganese dioxide, lead dioxide, a conductive polymer or the like is formed, and then a graphite layer and a silver paste layer are formed. Then, the cathode terminal is connected thereto by soldering or the like, and then sealed with resin to form a solid electrolytic capacitor.

For this reason, with the mixed powder having no proper flowability and angle of repose, it is difficult to flow from the hopper to the mold, and stable molding cannot be performed. In particular, since it is transported from the hopper using a method such as vibration, if the tapping density or average particle size of the blended powder is too large or too small, the mass of the molded body, the variation in the strength and shape of the sintered body becomes large, Chips and cracks may occur, resulting in a poor leakage current value. As described above, the tapping density, the average particle size, the flowability and the angle of repose of the mixed powder are important factors for producing good sintered bodies and capacitors.

Such physical properties of the blended powder hardly change before and after blending with the binder, and the physical properties of the blended powder are determined by the physical properties of the niobium powder for capacitors used. Therefore, the tapping density, average particle size, flowability, angle of repose, etc. of the niobium powder used are important. Since the flowability and the angle of repose of niobium powder are greatly influenced by the tapping density and the average particle size, the tapping density and the average particle size are important factors.

In order to obtain the effect of improving the productivity and the strength of the sintered body with the improvement of the flowability and the angle of repose, and the resulting reduction of the leakage current value, the tapping density in the present invention is
0.5-2.5 g / ml is preferable, 0.8-1.9 g
/ Ml is particularly preferred. The average particle size of the niobium powder of the present invention is preferably 10 to 1000 μm, and 50 to 20 μm.
0 μm is particularly preferable.

In order to allow the niobium powder to drop naturally from the molding machine hopper to the mold, the repose angle of the niobium powder of the present invention is 1.
0 to 60 degrees is preferable, and 10 to 50 degrees is particularly preferable.

The niobium powder having the above-mentioned physical properties includes niobium powder or niobium compound powder (hereinafter referred to as "raw material niobium powder") and activator (also referred to as "pore forming agent". It may be manufactured by using at least a sintering step and a crushing step as a raw material by using a mixture (hereinafter also referred to as an “additive”) (hereinafter referred to as a “raw material mixture”) as a raw material. The activator is removed in either the sintering step or the crushing step of producing the niobium powder of the present invention from the raw material mixture. The removal of the activator may be performed independently of the sintering step and the crushing step.

As a method of removing the activator, various methods can be arbitrarily adopted depending on the chemical properties of the activator,
Any one or a combination of methods that facilitate removal of the activator may be used. Examples of the method of removing the activator include a method of removing the activator by evaporating, subliming or thermally decomposing the activator into a gas, and a method of removing the activator by dissolving it in a solvent.

When the activator is removed in the form of gas, it may be carried out in the sintering step, or a step of removing the activator by heating and / or reducing pressure may be provided before the sintering. When the activator is dissolved and removed in a solvent, the activator is dissolved and removed by contacting the solvent described below with the sintered product or the crushed product after sintering the raw material mixture, or during the crushing, or after the crushing. .

Further, in any of the steps of producing the niobium powder of the present invention from the raw material mixture, a step of nitriding, borating, carbonizing or sulfiding a part of the niobium powder may be provided.

The method for producing niobium powder according to the present invention will be described in detail below. As the raw material niobium powder, at least one kind of powder selected from niobium, niobium hydride, niobium alloy, and niobium hydride alloy can be used. Further, some of these may be nitrided, sulfurized, carbonized, or borated. The alloy used in the present invention includes a solid solution with the other alloy component.
The average particle diameter of the raw material niobium powder is preferably 0.01 to 10 μm, more preferably 0.02 to 5 μm, and 0.05 to 2
μm is particularly preferable.

The method for obtaining niobium as the raw material niobium powder is as follows:
For example, a method of hydrogenating niobium ingot, niobium pellets, niobium powder, etc., crushing, dehydrogenation, a method of reducing potassium fluorinated niobate with sodium etc. and crushing, niobium oxide with hydrogen, carbon, magnesium, aluminum And the like, and a method of pulverizing the reduced product, a method of reducing niobium halide with hydrogen, and the like.

As a method of obtaining hydrogenated niobium as a raw material niobium powder, for example, a method of hydrogenating niobium ingot, niobium pellets, niobium powder and the like and pulverizing them can be mentioned.

The method of obtaining the hydrogenated niobium alloy as the raw material niobium powder can be obtained by, for example, a method of pulverizing a hydride of niobium alloy ingot, niobium alloy pellets, niobium alloy powder, or the like. As a method for obtaining a niobium alloy which is a raw material niobium powder, there is a method for dehydrogenating this hydrogenated niobium alloy.

The niobium alloy and the hydrogenated niobium alloy are hydrogen, nitrogen, oxygen, fluorine, chlorine, from the group consisting of elements having an atomic number of 88 or less as alloy components other than niobium.
Bromine, iodine, niobium, helium, neon, krypton,
It contains at least one element selected from the group excluding argon, xenon, and radon.

The activator is a substance that can be removed during any step of producing the niobium powder of the present invention from a raw material mixture. Usually, in the niobium powder of the present invention, the portion where the activator is removed forms pores.

The particle size of the activator affects the pore diameter of the niobium powder of the present invention, the pore diameter of the niobium powder affects the pore diameter of the niobium sintered body, and the pore diameter of the sintered body is It affects the capacity of the capacitor and the impregnation property of the cathodic agent in the capacitor manufacturing process.

The impregnation property of the cathodic agent has a great influence on the production of a capacitor having a high capacity and a low ESR.
Since the niobium sintered body is formed by press-molding niobium powder, the pore diameter of the sintered body is necessarily smaller than the pore diameter of the niobium powder. Considering the difficulty of impregnating the catholyte with a sintered body made of powder having a small peak of pore diameter, the pore diameter of niobium powder is 0.5 μm or more, especially 1 μm or more as an average diameter. Is desirable.

The average diameter of these pores is 0.0
1 to 500 μm is preferable, 0.03 to 300 μm is more preferable, and 0.1 to 200 μm is particularly preferable. Therefore, the average particle size of the activator is 0.01 to 500 μm.
Is preferred, 0.03-300 μm is more preferred,
0.1 to 200 μm is particularly preferable.

The most preferable pore diameter of the niobium powder is 0.5 μm to 100 μm as an average diameter, and the most preferable activator for producing this pore diameter has an average particle diameter of 0.5.
μm to 100 μm. To reduce the pore diameter, an activator with a small particle size may be used, and to increase it, an activator with a large particle size may be used.

The pore diameter distribution can be adjusted by adjusting the particle size distribution of the activator. In order to obtain a capacitor having a sufficient capacity without the problem of impregnation with the cathodic agent, pores that are small enough to obtain the desired capacity and large enough that the cathodic agent is sufficiently impregnated are obtained in the niobium sintered body. It is preferable that the pores are appropriately provided in accordance with the physical properties of the cathodic agent.

In order to adjust the pore diameter distribution of the niobium powder or the niobium sintered body, for example, an activator (powder) having a particle size distribution having two or more peak tops is used, and the niobium powder has two peak tops. It is possible to have more than one pore diameter distribution. By sintering this niobium powder, it is possible to obtain a niobium sintered body having a pore size distribution with two or more peak tops having the same pore size. In this case, the pore diameter peak top is preferably in the range of 0.01 to 500 μm, more preferably 0.03 to 300 μm, further preferably 0.1 to 200 μm, and 0.1 to
30 μm is particularly preferable, and 0.2 to 3 μm is most preferable.

The niobium powder that gives such a niobium sintered body has two or more pore diameter peak tops. It is desirable that two or more pore diameter peak tops of this niobium powder are 0.5 μm or more. For example, 0.7
When making a niobium sintered body having two pore diameter peak tops at μm and 3 μm, the two pore diameter peak tops at which niobium powder has are, for example, about 1.5 μm and about 25 μm.
Adjust it to.

The activator giving a small pore diameter of about 1.5 μm has an average particle size of about 1.5 μm, and the activator giving a large pore diameter of about 25 μm has an average particle size of about 25 μm. Is. Usually, when the niobium powder has a small pore diameter and a large pore diameter, the large pore diameter is crushed and reduced during the pressure molding. Therefore, it is desirable that the peak top of the large pore diameter is 20 μm or more. Even when there are three pore diameter peak tops, the large pore diameter peak tops are preferably 20 μm or more. Further, 30% by volume or more of the total pore volume preferably has a pore diameter of 20 μm or more, and particularly preferably 40% by volume or more.

Further, the above example will be described in detail with reference to the drawings. FIG. 1 is a sectional view schematically showing a state of the niobium powder of the present invention. The niobium powder of the present invention is a granulated powder having primary pores formed by an activator and having specific pores. The pores A are pores formed by an activator having an average particle size of about 1.5 μm, and the pores B have an average particle size of about 25 μm.
It is the pores formed by the activator. in this way,
It is possible to efficiently aggregate the primary powders. FIG. 2 is a schematic diagram when the pore distribution of the niobium powder of the present invention is measured by the mercury porosimetry method. The peak A is the peak of the pore A formed by the activator of about 1.5 μm, and the peak B is the peak of the pore B formed by the activator of about 25 μm. The height of peak B is higher than that of peak A, and the total pore volume is 4
4% have a pore diameter of 20 μm or more.

The activator having two or more peaks in the particle size distribution can be obtained by mixing two or more activators having different peaks in the particle size distribution.

Examples of the substance serving as an activator include a substance which becomes a gas at a sintering temperature or lower, or at least a substance which is soluble in a solvent after sintering.

As a substance which becomes a gas at a temperature below the sintering temperature,
For example, a substance that vaporizes, sublimates, or thermally decomposes into a gas, etc.
Gas without leaving a residue even at low temperatures.
An inexpensive substance is preferred. As such a substance,
For example, fragrances such as naphthalene, anthracene, and quinone
Group compounds, camphor, NH_FourCl, ZnO, WO₂, Sn
O ₂, MnO₃, Organic polymers.

Examples of organic polymers include polyacrylic acid, polyacrylic acid ester, polyacrylamide, polymethacrylic acid, polymethacrylic acid ester, polymethacrylamide, and polyvinyl alcohol.

The substance which is soluble at least after sintering is a substance in which the residue of the activator or its thermal decomposition product is soluble in the solvent, and after sintering, during crushing, or after crushing, A substance that is easily dissolved in the solvent described below is particularly preferable, but many substances can be selected depending on the combination with the solvent.

Examples of such substances include compounds of metals with carbonic acid, sulfuric acid, sulfurous acid, halogens, perhalogenic acids, hypohalous acid, nitric acid, nitrous acid, phosphoric acid, acetic acid, oxalic acid, or boric acid, and metal oxides. Materials, metal hydroxides, and metals. Preferably, acid, alkali, a compound having a large solubility in a solvent such as ammonium salt solution, for example, lithium, sodium, potassium, rubidium,
Cesium and francium, beryllium, magnesium, calcium, strontium, barium, radium, scandium, yttrium, cerium, neodymium, erbium, titanium, zirconium, hafnium,
Vanadium, niobium, tantalum, molybdenum, tungsten, manganese, rhenium, ruthenium, osmium,
Cobalt, rhodium, iridium, nickel, palladium, platinum, silver, gold, zinc, cadmium, aluminum,
Gallium, indium, thallium, germanium, tin,
Examples thereof include compounds containing at least one selected from the group consisting of lead, antimony, bismuth, selenium, tellurium, polonium, boron, silicon, and arsenic. Of these, metal salts are preferable, and more preferable examples include barium oxide, manganese (II) nitrate, and calcium carbonate. These activators may be used alone or in combination of two or more without any problem.

Considering efficient formation of specific pores, a substance existing as a solid at the sintering temperature is preferable.
This is because the activator is present as a solid at the sintering temperature to block unnecessary agglomeration of the primary niobium powder to cause fusion of niobium only at the contact point between niobium. When present as a liquid or gas at the sintering temperature, it has less of a blocking effect and may form pores smaller than desired. Therefore,
A substance having a low melting point, for example, aluminum metal, magnesium metal, magnesium hydride, calcium metal or the like, when used as an activator, a higher melting point, for example, barium oxide, calcium carbonate, aluminum oxide, magnesium oxide, etc. activator The pore size is more stable when used as.

If the amount of the activator added is small, the tapping density and the angle of repose will be large, and if it is large, the tapping density will be small and the number of closed holes at the sintering stage will be large. In order to obtain a tapping density of 0.5 to 2.5 g / ml at a repose angle of 60 degrees or less without the problem of closed pores at the sintering stage, it depends on the average particle diameter of the activator, but generally, 1% by mass or more and 40% by mass or less with respect to the raw material niobium (hereinafter, simply referred to as% by mass unless otherwise specified), preferably 5% or more and 25% or less, more preferably 10% or more 2
It is 0% or less.

The raw material mixture may be a mixture of the above-mentioned activator and the above-mentioned niobium raw material in the form of powder without solvent, or may be a mixture of the two in a suitable solvent and dried.

Examples of the solvent that can be used include water, alcohols, ethers, cellosolves, ketones, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons and the like. A mixer can be used for mixing.
As the mixer, a usual device such as a shaker mixer, a V-type mixer, and a Nauter mixer can be used without any problem. The temperature for mixing is limited by the boiling point and freezing point of the solvent, but it is generally -50 ° C to 120 ° C, preferably -5 ° C.
It is 0 ° C to 50 ° C, more preferably -10 ° C to 30 ° C. The time required for mixing is not particularly limited as long as it is 10 minutes or more, but is usually 1 to 6 hours, and it is desirable to perform the mixing in an oxygen-free atmosphere using an inert gas such as nitrogen or argon.

When a solvent is used, the resulting mixture is dried at a temperature of less than 80 ° C., preferably less than 50 ° C., using a conical dryer, a tray dryer or the like. Drying at a temperature of 80 ° C. or higher is not preferable because the amount of oxygen in niobium or niobium hydride fine powder increases.

When the activator becomes a gas below the sintering temperature,
It is possible to remove the activator during sintering, but the process of removing the activator as a gas before sintering under conditions such as temperature, pressure and time that are easy to remove according to the chemical properties of the activator is independent. May be provided. In this case, for example, 100 ° C. to 80
The activator is distilled off at 0 ° C. under reduced pressure for several hours.

When niobium hydride or a niobium hydride alloy is used as the raw material niobium, dehydrogenation can be performed by this step regardless of the type of activator.

The sintering step is carried out under reduced pressure or a reducing atmosphere such as argon at 500 ° C. to 2000 ° C., preferably 8 ° C.
00 ° C to 1500 ° C, more preferably 1000 ° C to 1
Perform at 300 ° C. Preferably, after the completion of sintering, the temperature of niobium (also abbreviated as the product temperature) is cooled to 30 ° C. or lower, and 0.01 vol% to 10 vol%, preferably 0.1 vol%.
An inert gas such as nitrogen or argon containing oxygen of 1% by volume to 1% by volume is gradually added so that the product temperature does not exceed 30 ° C.
After standing for 8 hours or more, it is taken out to obtain a sintered mass. In the crushing step, the sintered mass is crushed to an appropriate particle size using a crusher such as a roll granulator.

When the activator is soluble in the solvent at least after the sintering step, an appropriate solvent is added to the sintered mass after sintering, before crushing, during crushing, after crushing, or in these multiple steps. The activator component is dissolved and removed by bringing it into contact with the crushed powder. For ease of removal, it is preferable to dissolve and remove the crushed powder after crushing.

The solvent used here is a solvent in which the solubility of the activator to be dissolved is sufficiently obtained, and it is preferable that the solvent is inexpensive and does not easily remain. For example, if the activator is water-soluble, water is used. If the organic solvent is soluble, an organic solvent such as methylisobutylketone, ethanol, dimethylsulfoylside (DMSO) is used, and if it is acid-soluble, nitric acid, sulfuric acid, phosphorus is used. Acid, boric acid, carbonic acid, hydrofluoric acid,
An acid solution of hydrochloric acid, hydrobromic acid, hydroiodic acid, organic acid or the like is used. If alkali-soluble, an alkali metal hydroxide,
If a soluble complex is formed using an alkaline earth metal hydroxide or an alkaline solution such as ammonia, the ligand thereof is ammonia, amines such as ethylenediamine, amino acids such as glycine, sodium tripolyphosphate and the like. Solutions of polyphosphoric acids, crown ethers, thiosulfates such as sodium thiosulfate, chelating agents such as ethylenediaminetetraacetic acid, etc. may be used.

Further, a solution of an ammonium salt such as ammonium chloride, ammonium nitrate or ammonium sulfate, a cation exchange resin or an anion exchange resin can be preferably used. It is desirable that the temperature for dissolving and removing the activator is low. Since niobium has a high affinity with oxygen, the niobium surface is oxidized if the temperature for dissolution and removal is high. Therefore, 5
It is preferably 0 ° C or lower. Dissolution and removal is preferably carried out at -10 ° C to 40 ° C, and particularly preferably carried out at 0 ° C to 30 ° C. For the above reason, it is preferable to select a method that generates less heat when dissolved and removed. For example, when a metal oxide or a metal is used as an activator, heat of neutralization is generated in the method of dissolving and removing with an acid. Therefore, for example, a method that does not generate heat is selected, such as a method of dissolving in water or an organic solvent, a method of forming a soluble complex using an ammonium nitrate salt aqueous solution or ethylenediaminetetraacetic acid, a method of dissolving in a solution containing an ion exchange resin. You can also

More specifically, the combination of the activator and the solvent is, for example, barium oxide and water, calcium oxalate and hydrochloric acid, aluminum oxide and sodium hydroxide aqueous solution, hafnium oxide and methyl isobutyl ketone, magnesium carbonate and ethylenediaminetetraacetic acid 4 Examples thereof include sodium salt aqueous solution.

After the activator is dissolved and removed, it is thoroughly washed and dried. For example, when barium oxide is removed with water, the electric conductivity of the wash water is 5 μS / c using ion-exchanged water.
Thoroughly wash to m or less. Next, under reduced pressure, the product temperature is 5
Dry below 0 ° C. The amount of the activator and the solvent component remaining here is usually 100 ppm or less, though it depends on the washing conditions.

In order to further improve the LC value of the niobium powder thus obtained, the sintered mass, or the niobium raw material powder, a part of the niobium powder is nitrided, borated, carbonized, sulphurized, or plural. You may perform these processes of.

The obtained niobium nitride, niobium boride, niobium carbide, niobium sulfide, or plural kinds thereof may be contained in the niobium powder of the present invention. The total content of each element of nitrogen, boron, carbon, and sulfur varies depending on the shape of the niobium powder, but is 0 ppm to 2
0,000 ppm, preferably 50 ppm-100,
000 ppm, more preferably 200 ppm to 2
It is 0000 ppm. If it exceeds 200,000 ppm, the capacitance characteristic deteriorates and it is not suitable as a capacitor.

As the nitriding method of niobium powder, any one of liquid nitriding, ion nitriding, gas nitriding and the like, or a combination thereof can be used. Gas nitriding in a nitrogen gas atmosphere is preferable because the apparatus is simple and the operation is easy. For example, the method of gas nitriding in a nitrogen gas atmosphere is achieved by leaving the niobium powder in a nitrogen atmosphere. The temperature of the nitriding atmosphere is 2000 ° C. or less, and the leaving time is 100 hours or less, so that the desired amount of niobium powder is obtained. Further, the processing time can be shortened by processing at a higher temperature.

The method for boring the niobium powder may be either gas boration or solid phase boration. For example, niobium powder may be used at a temperature of 2000 ° C. or lower under reduced pressure with a boron source such as boron pellets or boron halide such as trifluoroboron.
Leave it for a minute to 100 hours.

Carbonization of niobium powder includes gas carbonization, solid phase carbonization,
Either liquid carbonization may be used. For example, the niobium powder may be allowed to stand under reduced pressure at 2000 ° C. or lower for 1 minute to 100 hours together with a carbon source such as a carbon material or an organic substance having carbon such as methane.

The sulfurization method of niobium powder may be any of gas sulfurization, ion sulfurization and solid phase sulfurization. For example, the method of gas sulphurization in a sulfur gas atmosphere is accomplished by leaving the niobium powder in a sulfur atmosphere. The temperature of the sulfurizing atmosphere is 2000 ° C. or less, and the standing time is 100 hours or less, so that the desired amount of sulfurizing niobium powder is obtained. Also,
Processing time can be shortened by processing at a higher temperature.

The BET specific surface area of the niobium powder of the present invention obtained as described above is usually 0.5 to 40 m ² / g, preferably 0.7 to 10 m ² / g, more preferably 0.
It is 9-2 m < ² > / g.

The niobium powder of the present invention is prepared by mixing niobium powders having different tapping densities, particle sizes, angles of repose, BET specific surface areas, pore size distributions, nitriding, boriding, carbonizing and sulfurizing treatments. Good.

The sintered body of the present invention that can be used for the capacitor electrode is preferably manufactured by, for example, sintering the niobium powder of the present invention described above. For example, after niobium powder is pressure-molded into a predetermined shape, it is 1 at 10 ⁻⁵ to 10 ² Pa.
Minutes to 10 hours, 500 ° C to 2000 ° C, preferably 80
0 ° C to 1500 ° C, more preferably 1000 ° C to 13
A sintered body can be obtained by heating in the range of 00 ° C.

The pore size distribution of the sintered body obtained from the niobium powder of the present invention is usually 0.01 in terms of the pore diameter peak top.
Within the range of μm to 500 μm.

Further, by adjusting the pressure applied during molding to a specific pressure value, it is possible to give the sintered body more pore diameter peak tops than the number of pore diameter peak tops of niobium powder. I can. This pressure value varies depending on the physical properties of the niobium powder, the shape of the molded body, or the pressure molding conditions of the molding machine, etc., but is a pressure above which pressure molding is possible and at which the pores of the sintered body do not close. It is within the following range. A preferable pressurizing value can be determined by a preliminary experiment in accordance with the physical properties of the niobium powder to be molded so that the peak tops have a plurality of pore sizes. The pressure value can be adjusted, for example, by adjusting the load applied to the molded product of the molding machine.

The pore size distribution of the sintered body is such that pores that are small enough to obtain the desired capacity and pores that are large enough to be sufficiently impregnated with the catholyte according to the physical properties of the catholyte are included. It is preferable to have at least two pore size peak tops. As described above, a sintered body having a pore diameter distribution having a plurality of peak tops can provide a capacitor having a good counter electrode impregnation property and a high capacity appearance rate.

Further, among the plurality of pore diameter peak tops,
The peak top of the two peaks with the highest relative intensity is
0.2 to 0.7 μm and 0.7 to 3 μm respectively,
The moisture resistance of the capacitor produced from this sintered body becomes preferable when they are respectively present at 0.2 to 0.7 μm and 0.9 to 3 μm, respectively. Furthermore, if the peak top of the peak having the largest relative intensity among the plurality of pore diameter peak tops is on the larger diameter side than the peak top of the peak having the next largest relative intensity, a capacitor with better moisture resistance is obtained. Therefore, it is particularly preferable.

The specific surface area of the thus produced sintered body is
In general, it is 0.2m ² / g~7m ² / g. Generally, the larger the shape of the sintered body, the more difficult the impregnation of the counter electrode becomes. For example, when the size of the sintered body is 10 mm ³ or more, the sintered body having a pore diameter distribution having a plurality of peak tops of the present invention can be particularly effectively used.

The sintered body of the present invention may be partially nitrided. As the nitriding method, the method and reaction conditions applied to the niobium powder described above can be adopted. It is also possible to nitride a part of the niobium powder for producing the sintered body and further nitride a part of the sintered body produced from this powder.

It should be noted that oxygen is usually contained in such a sintered body.
500 to 70,000 mass ppm is contained. This is because there is natural oxidized oxygen contained in the niobium powder before sintering and oxygen added by natural oxidation after sintering. Further, the content of elements other than niobium, alloy forming elements, oxygen and nitrogen in the sintered body of the present invention is usually 400 mass ppm or less.

The sintered body of the present invention is, for example, 1300
When sintered at ℃, CV value (the conversion voltage value when differentiated at 80 ℃ 120 in 0.1 mass% phosphoric acid aqueous solution and 120
(Product with capacity in Hz) is 40,000 to 200,000 μ
It becomes FV / g.

Next, the manufacture of the capacitor element will be described. For example, a lead wire made of a valve metal such as niobium or tantalum and having an appropriate shape and length is prepared, and a part of the lead wire is inserted into the inside of the molded body during the pressure molding of the niobium powder described above. So that the lead wire is assembled and designed so as to be the lead of the sintered body, or the lead wire separately prepared after molding and sintering without the lead wire is connected by welding or the like. To design.

A capacitor can be manufactured using the above-mentioned sintered body as one electrode and a dielectric interposed between the electrode and the counter electrode. For example, using niobium sintered body as one electrode,
A dielectric is formed on the surface of the sintered body (including the surface inside the pores), and a counter electrode is provided on the dielectric to form a capacitor.

Here, as the dielectric of the capacitor, a dielectric mainly containing niobium oxide is preferable, and a dielectric mainly containing niobium pentoxide is more preferable. The dielectric mainly composed of niobium pentoxide can be obtained, for example, by electrolytically oxidizing a niobium sintered body which is one of the electrodes.
The electrolytic oxidation of the niobium electrode in the electrolytic solution is usually performed using a protic acid aqueous solution, for example, a 0.1% phosphoric acid aqueous solution, a sulfuric acid aqueous solution or a 1% acetic acid aqueous solution, an adipic acid aqueous solution, or the like. As described above, when the niobium electrode is formed in the electrolytic solution to obtain the niobium oxide dielectric, the capacitor of the present invention serves as an electrolytic capacitor and the niobium electrode serves as the anode.

In the capacitor of the present invention, the counter electrode (counter electrode) of the niobium sintered body is not particularly limited. For example, an electrolytic solution known in the aluminum electrolytic capacitor industry,
At least one material (compound) selected from organic semiconductors and inorganic semiconductors can be used.

Specific examples of the electrolytic solution include a mixed solution of dimethylformamide and ethylene glycol in which 5% by mass of isobutyltripropylammonium borotetrafluoride electrolyte is dissolved, and propylene carbonate in which 7% by mass of tetraethylammonium borotetrafluoride is dissolved. Examples include a mixed solution of ethylene glycol.

Specific examples of the organic semiconductor include an organic semiconductor containing benzopyrroline tetramer and chloranil, an organic semiconductor containing tetrathiotetracene as a main component, an organic semiconductor containing tetracyanoquinodimethane as a main component, or the following general compounds. Examples of the conductive polymer include a repeating unit represented by the formula (1) or the general formula (2).

[0097]

[Chemical 5]

In the formula, R ^{1 to} R ⁴ are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 10 carbon atoms, an alkoxy group or an alkyl ester group, or a halogen atom. Represents a monovalent group selected from the group consisting of a nitro group, a cyano group, a primary, secondary or tertiary amino group, a CF ₃ group, a phenyl group and a substituted phenyl group. The hydrocarbon chains of R ¹ and R ² and R ³ and R ⁴ are bonded to each other at any position, and at least one saturated or unsaturated 3 to 7 membered ring together with the carbon atom substituted by such a group. You may form the bivalent chain which forms the cyclic structure of a saturated hydrocarbon. The cyclic bond chain may contain a bond of carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl and imino at any position. X represents an oxygen, sulfur or nitrogen atom, R ⁵ is present only when X is a nitrogen atom, and is independently hydrogen or a linear or branched saturated or unsaturated alkyl group having 1 to 10 carbon atoms. Represents

Further, in the present invention, the above general formula
R in (1) or general formula (2)¹~ R^FourIs preferably
Each independently a hydrogen atom, straight chain having 1 to 6 carbon atoms
Or branched saturated or unsaturated alkyl group or alkyl
Represents a Coxy group, R¹And R²And R ³And R^FourAre bound to each other
It may be circular.

Further, in the present invention, the conductive polymer containing the repeating unit represented by the general formula (1) is
A conductive polymer containing a structural unit represented by the following general formula (3) as a repeating unit is preferable.

[0101]

[Chemical 6]

In the formula, R ⁶ and R ⁷ are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or the alkyl groups are located at arbitrary positions. Represents a substituent which forms a cyclic structure of at least one or more 5- to 7-membered saturated hydrocarbon containing two oxygen elements. The cyclic structure includes those having a vinylene bond which may be substituted and those having a phenylene structure which may be substituted.

A conductive polymer having such a chemical structure is doped with a dopant. Known dopants can be used as the dopant without limitation.

Specific examples of the inorganic semiconductor include an inorganic semiconductor containing lead dioxide or manganese dioxide as a main component and an inorganic semiconductor containing triiron tetraoxide. Such semiconductors may be used alone or in combination of two or more.

Examples of the polymer containing the repeating unit represented by the general formula (1) or (2) include polyaniline, polyoxyphenylene, polyphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and these. Substituted derivatives and copolymers thereof are listed. Among them, polypyrrole, polythiophene and substituted derivatives thereof (for example, poly (3,4-ethylenedioxythiophene) etc.) are preferable.

When an organic semiconductor or an inorganic semiconductor having an electric conductivity in the range of 10 ^-2 S / cm to 10 ³ S / cm is used, the impedance value of the produced capacitor becomes smaller and the capacitance at high frequencies is further increased. Can be large.

As the method for producing the conductive polymer layer, for example, aniline, thiophene, furan, pyrrole,
A method in which a polymerizable compound of methylpyrrole or a substituted derivative thereof is polymerized by the action of an oxidant capable of sufficiently performing an oxidation reaction of dehydrogenative two-electron oxidation is adopted. The polymerization reaction from the polymerizable compound (monomer) includes, for example, gas phase polymerization of the monomer, solution polymerization, etc., and is formed on the surface of the niobium sintered body having a dielectric. When the conductive polymer is a solution-soluble polymer soluble in an organic solvent, a method of coating on the surface to form the conductive polymer is adopted.

As one of preferred production methods by solution polymerization, a niobium sintered body having a dielectric layer formed thereon is dipped in a solution containing an oxidizing agent (solution 1), and then a solution containing a monomer and a dopant (solution 2). A method of immersing in and polymerizing to form a conductive polymer layer on the surface is exemplified. Also,
The sintered body may be dipped in the solution 2 and then in the solution 1. The solution 2 may be used in the above method as a monomer solution containing no dopant. When a dopant is used, it may be used together with a solution containing an oxidizing agent.

Such polymerization process operation is performed once or more, preferably 3 to 3 times for the above-mentioned niobium sintered body having a dielectric material.
By repeating 20 times, a dense and layered conductive polymer layer can be easily formed.

In the method for producing a capacitor of the present invention, the oxidizing agent is an oxidizing agent that can improve the electric conductivity of the conductive polymer by using the reduced form of the oxidizing agent as a dopant without adversely affecting the performance of the capacitor. It is sufficient that a compound that is industrially inexpensive and easy to handle in production is preferred.

Specific examples of such an oxidizing agent include:
For example, FeCl ₃ , FeClO ₄ , Fe (III) -based compounds such as Fe (organic acid anion) salts, or anhydrous aluminum chloride / cuprous chloride, alkali metal persulfates, ammonium persulfate salts, peroxides, peroxides, Manganese such as potassium manganate, quinones such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetrachloro-1,4-benzoquinone and tetracyano-1,4-benzoquinone, Halogens such as iodine and bromine,
Examples thereof include peracid, sulfuric acid, fuming sulfuric acid, sulfur trioxide, chlorosulfuric acid, fluorosulfuric acid, sulfonic acid such as amido sulfuric acid, ozone and the like, and combinations of a plurality of these oxidizing agents.

Among these, examples of the basic compound of the organic acid anion forming the Fe (organic acid anion) salt include organic sulfonic acid or organic carboxylic acid, organic phosphoric acid and organic boric acid. Specific examples of the organic sulfonic acid include benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, α-sulfo-naphthalene, β-sulfo-naphthalene, naphthalenedisulfonic acid, alkylnaphthalenesulfonic acid (alkyl group). Examples thereof include butyl, triisopropyl, di-t-butyl and the like).

On the other hand, specific examples of the organic carboxylic acid include:
Examples thereof include acetic acid, propionic acid, benzoic acid and oxalic acid. Furthermore, in the present invention, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyvinyl sulfate poly-α-methyl sulfonic acid,
Polyelectrolyte anions such as polyethylene sulphonic acid, polyphosphoric acid are also used. The examples of these organic sulfonic acids or organic carboxylic acids are merely examples, and the present invention is not limited to these. Examples of the counter cation of the anion include an alkali metal ion such as H ⁺ , Na ⁺ , and K ⁺ , or an ammonium ion substituted with a hydrogen atom, a tetramethyl group, a tetraethyl group, a tetrabutyl group, a tetraphenyl group, or the like. However, the present invention is not limited to these. Among the above-mentioned oxidizing agents, particularly preferable are oxidizing agents containing trivalent Fe-based compounds, cuprous chloride-based compounds, alkali persulfate salts, ammonium persulfate acids and quinones.

In the method for producing a polymer composition of a conductive polymer, an anion having a dopant ability (an anion other than the reducing anion of an oxidant) coexisted as necessary,
An electrolyte anion having an oxidant anion (reduced form of the oxidant) produced from the aforementioned oxidant as a counter ion, or another electrolyte anion can be used. Specifically, for example, halide anions of Group 5B elements such as PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , halide anions of Group 3B elements such as BF ₄ ⁻ , I ⁻ (I ₃ ⁻ ), Br ⁻ , A halogen anion such as Cl ^−, a perhalogenate anion such as ClO ₄ ^−, a Lewis acid anion such as AlCl ₄ ⁻ , FeCl ₄ ⁻ and SnCl ₅ ⁻ or an inorganic acid anion such as NO ₃ ⁻ and SO ₄ ^2−. Or a sulfonic acid anion such as p-toluenesulfonic acid, naphthalenesulfonic acid, an alkyl-substituted naphthalenesulfonic acid having 1 to 5 carbon atoms (abbreviated as C1-5), CF ₃ SO ₃ ⁻ , CH ₃ SO ₃ ⁻ , etc. Examples thereof include organic sulfonic acid anions, or protonic acid anions such as carboxylic acid anions such as CH ₃ COO ⁻ and C ₆ H ₅ COO ⁻ .

Similarly, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyvinyl sulfuric acid, poly-α-methyl sulfonic acid,
Examples thereof include anions of polyelectrolytes such as polyethylene sulfonic acid and polyphosphoric acid, but are not limited thereto. However, preferably, anions of high molecular weight and low molecular weight organic sulfonic acid compounds or polyphosphoric acid compounds are mentioned, and preferably aromatic sulfonic acid compounds (sodium dodecylbenzene sulfonate, sodium naphthalene sulfonate, etc.) Used as anion-donating compound.

[0116] Among the organic sulfonate anions, the more effective dopant, one or more sulfo anion group in the molecule (-SO ₃ ^-) or sulfoquinone compound having a quinone structure, anthracene sulfonate anion To be

As the basic skeleton of the sulfoquinone anion of the sulfoquinone compound, p-benzoquinone, o-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, 2,6-naphthoquinone, 9,10-anthraquinone, 1,4 -Anthraquinone, 1,2-anthraquinone, 1,4-chrysenequinone, 5,6-chrysenequinone, 6,12-chrysenequinone, acenaphthoquinone, acenaphthenequinone, camphorquinone, 2,3-bornanedione, 9,10-phenanthrenequinone, 2 , 7-pyrenequinone.

When the counter electrode (counter electrode) is solid, a conductor layer may be provided thereon in order to improve electrical contact with an external lead lead (for example, a lead frame) which is optionally used. .

The conductor layer can be formed, for example, by solidifying a conductive paste, plating, metal deposition, a heat-resistant conductive resin film, or the like. As the conductive paste, silver paste, copper paste, aluminum paste, carbon paste, nickel paste and the like are preferable, but these may be used alone or in combination of two or more. When two or more types are used, they may be mixed or may be stacked as separate layers. After applying the conductive paste, it is left in the air or heated to solidify. As for plating,
Examples include nickel plating, copper plating, silver plating, aluminum plating. Further, examples of the vapor deposition metal include aluminum, nickel, copper, silver and the like.

Specifically, for example, a carbon paste and a silver paste are sequentially laminated on the second electrode and sealed with a material such as an epoxy resin to form a capacitor. The capacitor may have niobium or tantalum leads that are sintered together with the niobium sinter or are subsequently welded.

The capacitor of the present invention having the above-described structure can be used as a capacitor product for various purposes by, for example, resin molding, a resin case, a metallic outer case, resin dipping, and a laminated film outer case.

When the counter electrode is a liquid, the capacitor formed of the both electrodes and the dielectric is housed in, for example, a can electrically connected to the counter electrode to form the capacitor. In this case, the electrode side of the niobium sintered body is designed to be led out to the outside through the niobium or tantalum lead described above, and at the same time, insulated from the can by the insulating rubber or the like.

As described above, a niobium powder produced according to the embodiment of the present invention described above is used to produce a sintered body for a capacitor, and a capacitor is produced from the sintered body.
A highly reliable capacitor having a small leakage current value can be obtained.

Further, the capacitor of the present invention has a large electrostatic capacity relative to the volume of the conventional tantalum capacitor, and a smaller capacitor product can be obtained.

The capacitor of the present invention having such characteristics can be applied to, for example, bypass capacitors and coupling capacitors often used in analog circuits and digital circuits, and conventional tantalum capacitors.

In general, since such a capacitor is often used in an electronic circuit, if the capacitor of the present invention is used,
The restrictions on the arrangement of electronic components and the exhaust heat are alleviated, and a highly reliable electronic circuit can be stored in a narrower space than before.

Furthermore, if the capacitor of the present invention is used,
It is possible to obtain electronic devices that are smaller and more reliable than before, such as computers, computer peripheral devices such as PC cards, mobile devices such as mobile phones, home appliances, vehicle-mounted devices, artificial satellites, and communication devices.

[0128]

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The tapping density, repose angle, particle diameter and pore diameter of niobium powder, and the capacity, leakage current value, capacity appearance rate, humidity resistance value and ESR value of the capacitor in each example were measured by the following methods.

(1) Tapping Density Measurement The tapping density is in accordance with the method using a tapping device among the methods for measuring the apparent specific gravity of industrial sodium carbonate specified in JIS (Japanese Industrial Standard 2000) K1201-1, and the measuring equipment. Measured.

(2) Measurement of angle of repose The angle of repose can be measured according to JIS (Japanese Industrial Standard 2000 version) Z25.
Using the flow measurement equipment and sample amount specified in 04, drop niobium powder from the height of the hopper 6 cm below the horizontal plane to the horizontal plane, and from the apex of the resulting cone to the angle of repose to the horizontal plane of the slope to the horizontal plane. And

(3) Particle size measurement: manufactured by Microtrac (HRA 9320-X100)
The particle size distribution was measured by the laser diffraction scattering method using the above apparatus. The particle size value (D ₅₀ ; μm) corresponding to the cumulative volume% of 50% by volume was taken as the average particle size.

(4) Pore Diameter Measurement Poresier manufactured by Micro Meritics
9320 was used to measure the pore size distribution by mercury porosimetry. In the present invention, the maximum value was obtained from the change rate of the press-fitting amount, the pore diameter indicated by the maximum value was taken as the peak top, and the maximum value was taken as the magnitude of the relative intensity of the peak to which this peak top belongs.

(5) Capacitance Measurement of Capacitor At room temperature, an LCR measuring instrument manufactured by Hewlett-Packard was connected between the terminals of the produced chip, and the capacitance measurement value at 120 Hz was taken as the capacitance of the chip-processed capacitor.

(6) Measurement of Leakage Current of Capacitor At room temperature, a DC voltage of 6.
The current value measured after continuously applying 3 V for 1 minute was taken as the leakage current value of the capacitor processed into a chip.

(7) Capacitance appearance rate of capacitor 10% in a 0.1% phosphoric acid aqueous solution at 80 ° C. and 20 V.
The sintered body after chemical conversion for 00 minutes was expressed as a ratio with the capacity after forming a capacitor, with the capacity measured in 30% sulfuric acid as 100%.

(8) Humidity resistance value of capacitor When the manufactured capacitor was left at 60 ° C. and 95% RH for 500 hours, the capacity was less than 110% of the initial value and 1 or less.
The number is expressed as less than 20%. The more the number of particles less than 110%, the better the moisture resistance value. (9) ESR measurement of capacitor At room temperature, a Hewlett Packard LCR measuring device was connected between terminals of the produced chip, and 100 kHz,
1.5 VDC, 0.5 Vrms. The ESR measurement value in Example 1 was taken as the ESR of the chip-processed capacitor. Example 1: In a nickel crucible, 5000 g of potassium fluorinated niobate that had been sufficiently vacuum-dried at 80 ° C. was charged with 10 times the molar amount of sodium fluorinated niobate, and reduced at 1000 ° C. for 20 hours under an argon atmosphere. The reaction was carried out. After the reaction, the reaction product was cooled, and the reduced product was washed with water, successively washed with 95% sulfuric acid and water, and then vacuum dried. Further, after crushing for 40 hours using a ball mill having an alumina pot containing silica-alumina balls, the crushed product was mixed with 50% nitric acid and 10%.
The mixture was immersed and stirred in a 3: 2 (mass ratio) mixed solution of hydrogen peroxide water. Then, it was sufficiently washed with water until the pH reached 7, to remove impurities, and dried in vacuum. The raw material niobium powder had an average particle diameter of 1.2 μm.

500 g of this raw material niobium powder was placed in a niobium pot, and 50 g of polymethylmethacrylic acid butyl ester having an average particle diameter of 1 μm and 1 liter of toluene were added. Further, zirconia balls were added and mixed with a shaking mixer for 1 hour. The mixture from which the zirconia balls were removed was placed in a conical dryer and 1 × 10 ² Pa, 8
It was vacuum dried under the condition of 0 ° C.

Subsequently, this niobium powder was added at 1 × 10 ^-2 Pa,
It is heated at 250 to 400 ° C. for 12 hours to decompose and remove polymethylmethacrylic acid butyl ester, and further 4 × 10
^It was sintered at 1150 ° C. for 2 hours under a reduced pressure of ⁻³ Pa. After cooling the product temperature to 30 ° C. or lower, the niobium sinter lump was crushed with a roll granulator to obtain crushed niobium powder having an average particle diameter of 100 μm.

The crushed powder of niobium was subjected to nitriding treatment at 300 ° C. for 2 hours under a pressure of nitrogen to obtain about 450 g.
I got niobium powder. The nitrogen content was 0.22%.

Table 1 shows the physical properties of the niobium powder such as tapping density, average particle size, angle of repose, BET specific surface area and pore diameter peak top.

The niobium powder (about 0.1 g) thus obtained was put into a tantalum element automatic molding machine (TAP-2R manufactured by Seiken Co., Ltd.) hopper, and was automatically molded together with a niobium wire of 0.3 mmφ to obtain a large size. Approximately 0.3 cm x
A molded body was prepared to have a size of 0.18 cm × 0.45 cm. Table 1 shows the appearance and mass variation of this molded product.

Next, these compacts were left under vacuum at 4 × 10 ⁻³ Pa at 1250 ° C. for 30 minutes to obtain sintered compacts. 100 pieces of this sintered body were prepared, and a 0.1% phosphoric acid aqueous solution was used for electrolysis for 200 minutes at a voltage of 20 V to form a dielectric oxide film on the surface.

Then, the manganese dioxide layer was formed as a counter electrode layer on the dielectric oxide film by repeating the heating in the 60% manganese nitrate aqueous solution for 30 minutes at 220 ° C. Subsequently, a carbon layer and a silver paste layer were sequentially laminated on it. Next, after mounting a lead frame, the whole was sealed with an epoxy resin to manufacture a chip type capacitor. Table 1 shows the capacitance appearance ratio of this capacitor, and the average (n = 100) of the capacitance and the leakage current value (hereinafter abbreviated as “LC”) of this chip type capacitor. The LC value is a value when 6.3 V is applied for 1 minute at room temperature.

Example 2 1000 g of a niobium ingot was placed in a reaction vessel made of SUS304, and hydrogen was continuously introduced at 400 ° C. for 10 hours. After cooling, the hydrogenated niobium lump was placed in a SUS pot containing zirconia balls and ground for 10 hours. Next, a slurried 20% by volume slurry of this hydride with water and zirconia balls were placed in a spike mill, and wet milled at 40 ° C. or lower for 7 hours to obtain a milled slurry of niobium hydride. The average particle size of the raw material niobium hydride powder was 0.9 μm.

This slurry (slurry concentration 98%) was mixed with S
In a US pot, 200 g of barium oxide having an average particle size of 1 μm was added. Further, zirconia balls were added and mixed with a shaking mixer for 1 hour. The mixture from which the zirconia balls have been removed is placed in a niobium bat and 1 × 10
^It was dried under the conditions of ² Pa and 50 ° C.

Subsequently, the resulting mixture was mixed with 1 × 10 ^-2 P
a, heating at 400 ° C. for 4 hours to dehydrogenate niobium hydride,
Further, this mixture was subjected to 110 ° C. under reduced pressure of 4 × 10 ⁻³ Pa.
Sintered for 2 hours at 0 ° C. After cooling to a product temperature of 30 ° C. or lower, the barium oxide-mixed niobium sinter was crushed with a roll granulator to obtain barium oxide-mixed niobium crushed powder having an average particle diameter of 95 μm.

This barium oxide-mixed niobium crushed powder 50
0 g and 1000 g of ion-exchanged water were placed in a container made of polytetrafluoroethylene and cooled to 15 ° C or lower. Separately, 60 g nitric acid 600 g, 30% hydrogen peroxide 150 g, ion-exchanged water 7 cooled to 15 ° C. or lower
Prepare an aqueous solution mixed with 50 g and 500 g of this aqueous solution
While stirring, was added dropwise to an aqueous suspension of niobium crushed powder mixed with barium oxide so that the water temperature did not exceed 20 ° C. After completion of dropping, stirring was continued for another 1 hour, and the mixture was allowed to stand for 30 minutes and then decanted. Ion-exchanged water (2000 g) was added, the mixture was stirred for 30 minutes, allowed to stand for 30 minutes, and then decanted. This operation is repeated 5 times, and further niobium crushed powder is put into a column made of polytetrafluoroethylene,
Water washing was performed for 4 hours while flowing ion-exchanged water. The electric conductivity of the wash water at this time was 0.9 μS / cm.

The niobium crushed powder which has been washed with water is dried at 50 ° C. under reduced pressure, and nitrogen is circulated under pressure to make it 3
Nitriding treatment was performed at 00 ° C. for 3 hours to obtain about 350 g of niobium powder. The nitrogen content was 0.28%.

Table 1 shows the physical properties of this niobium powder such as tapping density, average particle size, angle of repose, BET specific surface area and average pore diameter.

The niobium powder (about 0.1 g) thus obtained was put into a tantalum element automatic molding machine (TAP-2R manufactured by Seiken Co., Ltd.) hopper and automatically molded together with a 0.3 mmφ niobium wire to obtain a large size. Approximately 0.3 cm x
A molded body was prepared to have a size of 0.18 cm × 0.45 cm. Table 1 shows the appearance and mass variation of this molded product.

Next, these compacts were left under reduced pressure of 4 × 10 ⁻³ Pa at 1250 ° C. for 30 minutes to obtain a sintered compact. 100 pieces of this sintered body were prepared, and a 0.1% phosphoric acid aqueous solution was used for electrolysis for 200 minutes at a voltage of 20 V to form a dielectric oxide film on the surface.

Subsequently, the dielectric oxide film is brought into contact with an equal volume mixture of 10% ammonium persulfate aqueous solution and 0.5% anthraquinonesulfonic acid aqueous solution, and then pyrrole vapor is contacted at least 5 times. As a result, a counter electrode (counter electrode) made of polypyrrole was formed.

Successively, a carbon layer and a silver paste layer were sequentially laminated on it. Next, after mounting a lead frame, the whole was sealed with an epoxy resin to manufacture a chip type capacitor. The capacitance appearance rate of this capacitor, and the average of the capacitance and LC value of this chip-type capacitor (n = 10
0) is shown in Table 1. The LC value was 6.3 V at room temperature, 1
It is the value when applied for a minute.

Examples 3 to 10: Using the same method as in Example 1, the average particle size and addition amount of polymethylmethacrylic acid butyl ester, and by using the same method as in Example 2, the average particle size of barium oxide, The amount of addition was changed, and niobium powder, its molded body, a sintered body, and a capacitor were produced. Table 1 shows the physical properties of these niobium powders, the appearance of molded products, the variation in mass, the capacitance of capacitors, and LC.

Examples 11 to 22: Examples 11 to 14 and 16 to 18 use the same method as in Example 1 and Example 15
And Nos. 19 to 22 used the same method as in Example 2 except that the activator shown in Table 1 was used instead of polymethylmethacrylic acid butyl ester or barium oxide to prepare niobium powder, a molded body and a sintered body. . Table 1 shows the physical properties of the niobium powder, the appearance of the molded product, and the variation in mass.

Next, these compacts were left under reduced pressure of 4 × 10 ⁻³ Pa at 1250 ° C. for 30 minutes to obtain sintered bodies. 100 pieces of this sintered body were prepared, and a 0.1% phosphoric acid aqueous solution was used for electrolysis for 200 minutes at a voltage of 20 V to form a dielectric oxide film on the surface.

Subsequently, the sintered body was immersed in an aqueous solution containing 25% by mass of ammonium persulfate (Solution 1), then pulled up, dried at 80 ° C. for 30 minutes, and then the sintered body having a dielectric formed thereon was
It was immersed in an isopropanol solution (solution 2) containing 18% by mass of 3,4-ethylenedioxythiophene, pulled up, and left standing in an atmosphere of 60 ° C. for 10 minutes to carry out oxidative polymerization. This was immersed again in the solution 1 and further treated in the same manner as described above. After repeating the operation from the immersion in the solution 1 to the oxidative polymerization 8 times, washing with warm water at 50 ° C. for 10 minutes and drying at 100 ° C. for 30 minutes were performed to obtain the conductive poly (3,3). A counter electrode (counter electrode) made of 4-ethylenedioxythiophene was formed.

Subsequently, a carbon layer and a silver paste layer were sequentially laminated thereon. Next, after mounting a lead frame, the whole was sealed with an epoxy resin to manufacture a chip type capacitor. The capacitance appearance rate of this capacitor, and the average of the capacitance and LC value of this chip-type capacitor (n = 10
0) is shown in Table 1. The LC value was 6.3 V at room temperature, 1
It is the value when applied for a minute.

Examples 23 to 25: Using the same method as in Example 2, the starting materials were Niobose alloy powder in Example 23, niobium hydride-rhenium alloy powder in Example 24, and niobium hydride in Example 25. -A yttrium-boron alloy powder was used to produce a niobium powder, a sintered body, and a capacitor. Its physical properties, capacity, and LC are shown in Table 1.

Comparative Examples 1-3: 80 ° C. in nickel crucible
2000 fully dried in vacuum with potassium fluoroniobate
Sodium was added to g in a molar amount 10 times that of potassium fluorinated niobate, and a reduction reaction was carried out at 1000 ° C. for 20 hours in an argon atmosphere. After the reaction, the reaction product was cooled, and the reduced product was washed with water, successively washed with 95% sulfuric acid and water, and then vacuum dried.
Furthermore, after crushing was performed by changing the crushing time using a ball mill of an alumina pot containing silica-alumina balls, the crushed product was immersed and stirred in a 3: 2 (mass ratio) mixture of 50% nitric acid and 10% hydrogen peroxide. . Then, it was sufficiently washed with water until the pH reached 7, to remove impurities, and dried in vacuum. The produced niobium powder had an average particle size of 1.3 to 10 μm.

50 g of each niobium powder thus obtained was placed in a reaction container made of SUS304 and heated to 300 ° C.
The nitrogen was continuously introduced for 2 to 4 hours to obtain a niobium nitride.

Table 1 shows the physical properties of the niobium powder such as tapping density, average particle diameter, repose angle, BET specific surface area and average pore diameter.

The niobium powder (about 0.1 g) thus obtained was put into a tantalum element automatic molding machine (TAP-2R manufactured by Seiken Co., Ltd.) hopper, and an attempt was made to perform automatic molding together with a niobium wire having a diameter of 0.3 mm. . The results are shown in Table 1.

Comparative Examples 4 to 9: The tapping density was 0.2 to 0.4 g / ml and 2.6 in the same manner as in Example 2 except that the addition amount of barium oxide having an average particle diameter of 1 μm was changed. ~ 3.3 g / ml of niobium powder was obtained. The physical properties of this product are shown in Table 1.

The niobium powder (about 0.1 g) thus obtained was put into a tantalum element automatic molding machine (TAP-2R manufactured by Seiken Co., Ltd.) hopper and automatically molded together with a 0.3 mmφ niobium wire to obtain a large size. Approximately 0.3 cm x
A molded body was prepared to have a size of 0.18 cm × 0.45 cm. Table 1 shows the appearance and mass variation of this molded product.

Next, these compacts were left for 30 minutes at 1250 ° C. under a vacuum of 4 × 10 ^-3 Pa to obtain sintered compacts. 100 pieces of this sintered body were prepared, and a 0.1% phosphoric acid aqueous solution was used for electrolysis for 200 minutes at a voltage of 20 V to form a dielectric oxide film on the surface.

Subsequently, a 10% aqueous solution of ammonium persulfate and a 0.5% aqueous solution of anthraquinonesulfonic acid are brought into contact with the dielectric oxide film, and then pyrrole vapor is touched at least 5 times. As a result, a counter electrode (counter electrode) made of polypyrrole was formed.

Subsequently, a carbon layer and a silver paste layer were sequentially laminated on it. Next, after mounting a lead frame, the whole was sealed with an epoxy resin to manufacture a chip type capacitor. The capacitance appearance rate of this capacitor, and the average of the capacitance and LC value of this chip-type capacitor (n = 10
0) is shown in Table 1. The LC value was 6.3 V at room temperature, 1
It is the value when applied for a minute.

Examples 26 to 31 Niobium ingot hydrides were pulverized and dehydrogenated to obtain primary particles having an average particle diameter of 0.8 μm. The primary particles were fired and crushed to obtain niobium granulated powder. 0.1 g of this granulated powder was prepared separately, length 10 mm, thickness 0.3
mm niobium wire and die (4.0 mm x 3.5 mm
× 1.8 mm), and a tantalum element automatic molding machine (TAP-2R manufactured by Seiken Co., Ltd.) was loaded as shown in Table 2 to prepare a molded body. Then, it was sintered at 1300 ° C. for 30 minutes to obtain a desired sintered body. By adjusting the load of the molding machine, a sintered body having a pore diameter distribution as shown in Table 2 was prepared. The size, specific surface area, and CV value of the sintered body of Example 26 were 24.7 mm ³ , 1.1 m ² /
g, 85,000 μFV / g, and the numerical values of other examples were within ± 2% of Example 26.

Examples 32 to 34 Sintered bodies were obtained in the same manner as in Examples 26 to 28 except that the average particle size of the primary particles was changed to 0.5 μm by classifying the primary particles. The size, specific surface area, and CV value of the sintered body of Example 32 were 24.9 mm ³ , 1.5 m ² /
g, 125,000 μFV / g, and the numerical values of other examples were within ± 1% of Example 32. The pore diameter distribution of the produced sintered body is shown in Table 2.

Example 35 A niobium powder obtained in the same manner as in Example 4 was used in place of the granulated powder, and a sintered body was obtained in the same manner as in Example 31. Example 35
The size, specific surface area, and CV value of the
The values were 4.8 mm ³ , 1.2 m ² / g and 78000 μFV / g. The pore diameter distribution of the produced sintered body is shown in Table 2.

Comparative Examples 10 to 12 Instead of the niobium granulated powder used in Examples 26 to 28,
1 niobium powder obtained by reducing niobium chloride with magnesium
Sintered bodies were produced in the same manner as in Examples 26 to 28 except that niobium powder obtained by heat treatment at 100 ° C. was used. The size, the specific surface area, and the CV value of the produced sintered body of Comparative Example 10 were 24.3 mm ³ , 0.8 m ² / g, and 84000 μFV, respectively.
/ G, and the numerical values of other examples are ± 2% of those of Comparative Example 10.
It was within. The pore diameter distribution of the produced sintered body is shown in Table 2.

Example 36 By the method of producing the sintered bodies in Example 21 and Examples 26 to 35, 60 similar sintered bodies were produced respectively, and each sintered body was immersed in a 0.1% phosphoric acid aqueous solution. At 80 ° C. for 1000 minutes at 20 V to form a dielectric oxide film layer on the surface of the sintered body. Next, each of the formed sintered bodies is divided into 30 pieces, each of which is divided into 30 pieces.
After a set of sintered bodies was impregnated with two kinds of cathodic agents A and B shown in Table 3, a carbon paste and a silver paste were sequentially laminated and sealed with an epoxy resin to produce a chip type capacitor. Table 4 shows the capacity appearance rate and the moisture resistance value of the manufactured capacitors.

Comparative Example 13 By the method of producing the sintered body in Comparative Examples 9 to 60, 60 similar sintered bodies were produced, and each sintered body was heated at 80 ° C. in a 0.1% phosphoric acid aqueous solution. The film was formed at 20 V for 1000 minutes to form a dielectric oxide film layer on the surface of the sintered body. Next, each of the formed sintered bodies was divided into 30 pieces, and each set of 30 sintered pieces was impregnated with the cathodic agent A shown in Table 3, and then a carbon paste and a silver paste were laminated in this order. A chip-type capacitor was manufactured by sealing with an epoxy resin. Table 4 shows the capacity appearance rate and the moisture resistance value of the manufactured capacitors.

Example 37: In the same manner as in Example 2, a ground slurry of raw material niobium hydride powder was obtained. The average particle size of this niobium hydride powder was 0.6 μm. This slurry was centrifuged and sedimented, and then decanted to remove the supernatant. Anhydrous acetone was added so as to have a slurry concentration of 40% by mass and well suspended, followed by centrifugal sedimentation to remove the supernatant. This operation was repeated 3 times. Anhydrous acetone was added so that the slurry concentration would be 60% by mass and well suspended. Put this slurry in a SUS pot,
Barium oxide having average particle diameters of 1.4 μm and 23 μm was added to niobium in an amount of 15% by mass and 10% by mass, respectively. Add zirconia balls and mix with a shaking mixer.
Mixed for hours. The mixture from which the zirconia balls were removed was placed in a niobium vat and dried under the conditions of 1 × 10 ² Pa and 50 ° C. Barium oxide mixed niobium sinter and crushed niobium powder were obtained in the same manner as in Example 2.

Ion-exchanged water 100 cooled to 15 ° C. or lower
To 0 g, 500 g of this barium oxide mixed niobium crushed powder
Was added while stirring so that the water temperature did not exceed 20 ° C. After the addition was completed, stirring was continued for another 1 hour, and the mixture was allowed to stand for 30 minutes and then decanted. Deionized water 2000g
Was added, the mixture was stirred for 30 minutes, allowed to stand for 30 minutes, and decanted. This operation was repeated 5 times, and the crushed niobium powder was placed in a column made of polytetrafluoroethylene and washed with water for 4 hours while flowing ion-exchanged water. The electric conductivity of the wash water at this time was 0.5 μS / cm.

The niobium crushed powder which has been washed with water is dried at 50 ° C. under reduced pressure, and nitrogen is circulated under pressure to make it 3
Nitriding treatment was performed at 00 ° C. for 3 hours to obtain about 350 g of niobium powder. The nitrogen content was 0.30%. Tapping density, average particle size, angle of repose, BE of this niobium powder
Table 5 shows physical properties such as T specific surface area and average pore diameter. A molded body was prepared in the same manner as in Example 2. Table 5 shows the appearance and variation in mass of this molded product.

Further, a dielectric film was formed by the same operation as in Example 2, then an electrode was formed, and a carbon layer and a silver paste layer were laminated. Next, after mounting the lead frame,
The whole was sealed with an epoxy resin to produce a chip type capacitor. The capacitance appearance rate of this capacitor, and the average of the capacitance and LC value of this chip type capacitor (n = 100
Are shown in Table 5.

Examples 38 to 44: In the same manner as in Example 37, the type of activator to be added, the average particle diameters of the two types of admixtures, and the addition amount were changed to obtain niobium crushed powder mixed with the activator. Obtained. The solvent for eluting the activator is selected from water, an acid, an alkali, a solution containing an ion exchange resin, an ammonium nitrate solution, and a solution containing ethylenediaminetetraacetic acid,
The activator was eluted in the same manner as in Example 37 to obtain niobium powder. The physical properties are shown in Table 5. Further, a molded body and a sintered body were prepared in the same manner as in Example 37 to prepare a chip type capacitor. Appearance of molded body, variation in mass,
Table 5 shows the average capacitance and LC of the capacitors.

Examples 45 to 47: Using the same method as in Example 37, the starting materials used in Example 45 were niobium-neodymium alloy powder, Example 46 was niobium-tungsten alloy powder, and Example 47 was niobium-tantalum alloy. Using powder, niobium alloy powder was obtained. The physical properties are shown in Table 5. Further, a molded body and a sintered body were prepared in the same manner as in Example 37 to prepare a chip type capacitor. Table 5 shows the appearance of the molded product, variation in mass, and average capacitance and LC of the capacitor.

Examples 48 to 58: Using the niobium powders produced in Examples 37 to 47, niobium sintered bodies were produced in the same manner as in Example 2. Table 6 shows the pore diameter distribution of the sintered body. Examples 59 to 69: 100 niobium sinters produced in each of Examples 48 to 58 were produced, and each sinter was formed in a 0.1% phosphoric acid aqueous solution at 80 ° C. for 1000 minutes at 20 V. A dielectric oxide film layer was formed on the surface of the sintered body. Next, after impregnating the formed sintered body with the cathodic agent A shown in Table 3,
A carbon paste and a silver paste were sequentially laminated and sealed with an epoxy resin to produce a chip type capacitor. Table 7 shows the capacitance appearance rate and ESR of the manufactured capacitors.

Comparative Examples 14 to 17: 100 niobium sintered bodies produced in Comparative Examples 9 to 12 were produced, and each sintered body was formed in a 0.1% phosphoric acid aqueous solution at 80 ° C. for 1000 minutes at 20V. Then, a dielectric oxide film layer was formed on the surface of the sintered body. Next, after the formed sintered body was impregnated with the cathode agent A shown in Table 3, a carbon paste and a silver paste were sequentially laminated and sealed with an epoxy resin to manufacture a chip type capacitor. Table 7 shows the capacitance appearance rate and ESR of the manufactured capacitors.

[0184]

[Table 1]

[0185]

[Table 2]

[0186]

[Table 3]

[0187]

[Table 4]

[0188]

[Table 5]

[0189]

[Table 6]

[0190]

[Table 7]

[0191]

The tapping density is 0.5 to 2.5 g / m.
1, the average particle size is 10 to 1000 μm, and the angle of repose is 10
The niobium powder for a capacitor of the present invention having a BET specific surface area of 60 ° and a BET specific surface area of 0.5 to 40 m ² / g has good flowability, can be continuously molded, and is obtained by sintering the niobium powder. Higher by using the niobium sintered body of the present invention having a pore diameter peak top in the range of 0.01 μm to 500 μm, and preferably having a pore distribution having a plurality of pore diameter peak tops, for a capacitor electrode. Capacitance appearance rate can be obtained, a leakage current is low, and a capacitor with good moisture resistance can be produced.

[0192]

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a state of niobium powder of the present invention.

FIG. 2 is a schematic diagram when the pore distribution of the niobium powder of the present invention is measured by the mercury penetration method.

[Explanation of symbols]

1 ... pore A 2 ... Pores B

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22C 27/02 102 C22C 27/02 102Z H01G 9/00 H01G 9/05 K 9/028 9/24 C 9 / 032 9/02 311 9/035 321 9/052 331C 331G 331F (72) Inventor Toshiya Kawasaki 5-1 Okawamachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko K.K. (72) Inventor Koichi Wada, Kanagawa 5-1, Okawa-cho, Kawasaki-ku, Kawasaki Prefecture, Japan F-Term in the Research and Development Center, Showa Denko KK (Reference) 4K017 AA04 BA07 CA07 DA08 EA01 EH01 EH04 EH18 FB02 FB04 FB06 FB09 FB10 4K018 AA40 BA20 BB01 BB04 BC13 CA11 DA03 DA12 DA21 DA32 DA27 FA27 FA27 KA39

Claims (63)

[Claims] 1. A tapping density of 0.5 to 2.5 g / ml.
Niobium powder for capacitors. 2. The niobium powder according to claim 1, which has an average particle diameter of 10 to 1000 μm. 3. The niobium powder according to claim 1, which has an angle of repose of 10 to 60 degrees. 4. The niobium powder according to claim 1, which has a BET specific surface area of 0.5 to 40 m ² / g. 5. The niobium powder according to claim 1, having a pore distribution having a pore diameter peak top in the range of 0.01 μm to 500 μm. 6. The niobium powder according to claim 5, wherein the pore distribution has a plurality of pore diameter peak tops. 7. All of the pore diameter peak tops are 0.5 μm.
The niobium powder according to claim 5, which is in the range of m to 100 μm. 8. The content of at least one element selected from the group consisting of elements of nitrogen, carbon, boron and sulfur is 2
The niobium powder according to any one of claims 1 to 7, having an amount of not more than 0,000 mass ppm. 9. A sintered body using the niobium powder according to any one of claims 1 to 8. 10. The sintered body according to claim 9, which has a pore distribution having a pore diameter peak top in the range of 0.01 μm to 500 μm. 11. A niobium sintered body for a capacitor electrode, wherein the pore distribution of the niobium sintered body has a plurality of pore diameter peak tops. 12. The niobium sintered body according to claim 11, wherein the pore distribution has two pore diameter peak tops. 13. The peak top of the two peaks having the largest relative intensities among the plurality of pore diameter peak tops is in the range of 0.2 to 0.7 μm and 0.7 to 3 μm, respectively. The niobium sintered body according to item 12. 14. The plurality of pore diameter peak tops, the peak top of the peak having the largest relative intensity is located on the larger diameter side than the peak top of the peak having the next largest relative intensity. The niobium sintered body according to item 1. 15. The sintered body has a pore volume of 10 m including pore volume.
The niobium sintered body according to claim 9, which has a volume of m ³ or more. 16. The niobium sintered body according to claim 9, wherein the sintered body has a specific surface area of 0.2 to 7 m ² / g. 17. The sintered body is partly nitrided.
The niobium sintered body according to any one of 1 to 16. 18. When the sintered body is sintered at 1300 ° C. 4
The niobium sintered body according to any one of claims 12 to 17, which is a sintered body obtained from a niobium compact which gives a sintered body having a CV value of 0000 to 200000 µFV / g. 19. A capacitor comprising the niobium sintered body according to any one of claims 9 to 18 as one electrode, and a dielectric interposed between the electrode and the counter electrode. 20. The capacitor according to claim 19, wherein the main component of the dielectric is niobium oxide. 21. The capacitor according to claim 19, wherein the counter electrode is at least one material selected from the group consisting of an electrolytic solution, an organic semiconductor and an inorganic semiconductor. 22. The counter electrode is an organic semiconductor, and the organic semiconductor mainly comprises benzopyrroline tetramer and chloranil, an organic semiconductor containing tetrathiotetracene as a main component, and tetracyanoquinodimethane. 22. The capacitor according to claim 21, which is at least one material selected from the group consisting of organic semiconductors and conductive polymers as components. 23. The capacitor according to claim 22, wherein the conductive polymer is at least one selected from polypyrrole, polythiophene, polyaniline and substituted derivatives thereof. 24. The conductive polymer is represented by the following general formula (1) or general formula (2): (In the formula, R ^{1 to} R ⁴ are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 10 carbon atoms, an alkoxy group or an alkyl ester group, a halogen atom, or a nitro group. Groups, cyano groups, 1
It represents a monovalent group selected from the group consisting of primary, secondary or tertiary amino group, CF ₃ group, phenyl group and substituted phenyl group. The hydrocarbon chains of R ¹ and R ² and R ³ and R ⁴ are bonded to each other at any position, and at least one saturated or unsaturated 3 to 7 membered ring together with the carbon atom substituted by such a group. You may form the bivalent chain which forms the cyclic structure of a saturated hydrocarbon. The cyclic bond chain may contain a bond of carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl and imino at any position.
X represents an oxygen, sulfur or nitrogen atom, R ⁵ is present only when X is a nitrogen atom, and is independently hydrogen or C 1 to C 1.
And 0 represents a linear or branched saturated or unsaturated alkyl group. 23. The capacitor according to claim 22, which is a conductive polymer obtained by doping a polymer containing a repeating unit represented by the formula (1) with a dopant. 25. The conductive polymer has the following general formula (3): (In the formula, R ⁶ and R ⁷ are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or the alkyl group is bonded to each other at any position. And represents a substituent forming a cyclic structure of at least one 5- to 7-membered saturated hydrocarbon containing two oxygen elements, and an optionally substituted vinylene bond is contained in the cyclic structure. 25. The capacitor according to claim 24, which is a conductive polymer including a repeating unit represented by the formula (1) or a phenylene structure which may be substituted. 26. The capacitor according to claim 22, wherein the conductive polymer is a conductive polymer obtained by doping poly (3,4-ethylenedioxythiophene) with a dopant. 27. The capacitor according to claim 19, wherein the counter electrode is made of a material having a layered structure in at least a part thereof. 28. The capacitor according to claim 19, wherein the counter electrode is a material containing an organic sulfonate anion as a dopant. 29. The method for producing niobium powder according to claim 1, wherein the niobium or niobium compound is activated in the method for producing niobium powder. 30. The production of niobium powder according to claim 29, wherein the activation treatment of niobium or a niobium compound is performed in at least one step selected from the group consisting of a sintering step and a crushing step. Method. 31. The method for producing niobium powder according to claim 29, wherein the activation treatment of niobium or a niobium compound is performed using a mixture containing niobium or a niobium compound and an activator. 32. The average particle size of niobium or a niobium compound is from 0.01 μm to 10 μm.
The method for producing the niobium powder according to any one of 1. 33. The niobium or niobium compound contains at least 200,000 ppm or less of at least one element selected from the group consisting of nitrogen, carbon, boron and sulfur. A method for producing the described niobium powder. 34. The method for producing niobium powder according to claim 29, wherein the niobium compound is at least one selected from the group consisting of niobium hydride, niobium alloys and niobium hydride alloys. 35. A niobium alloy and a hydrogenated niobium alloy, wherein the alloy components other than niobium are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine and niobium, selected from the group consisting of elements having an atomic number of 88 or less. 35. The method for producing niobium powder according to claim 34, which is at least one element selected from the group excluding helium, neon, argon, krypton, xenon, and radon. 36. The method for producing niobium powder according to claim 31, wherein a mixture containing niobium or a niobium compound and an activator is mixed using a solvent. 37. At least one solvent selected from the group consisting of water, alcohols, ethers, cellosolves, ketones, aliphatic hydrocarbons, aromatic hydrocarbons and halogenated hydrocarbons as the solvent. 37. The method for producing niobium powder according to claim 36. 38. The method for producing niobium powder according to claim 31, wherein the activator is used in an amount of 1 to 40% by mass based on the total amount of niobium or the niobium compound. 39. The activator has an average particle size of 0.01 to 500.
The method for producing niobium powder according to claim 31 or 38, wherein the niobium powder has a thickness of μm. 40. The method for producing niobium powder according to claim 31, 38, or 39, wherein the activator has a plurality of particle size peak tops. 41. The activator is a substance that is removed as a gas at 2000 ° C. or lower, according to any one of claims 31 to 40.
The method for producing the niobium powder according to the item. 42. The activator is naphthalene, anthracene,
Quinone, camphor, polyacrylic acid, polyacrylic acid ester
, Polyacrylamide, polymethacrylic acid, polymetha
Acrylic ester, polymethacrylamide, polyvinyl
Alcohol, NH _FourCl, ZnO, WO₂, SnO₂, M
nO₃A contract which is at least one selected from the group consisting of
The method for producing niobium powder according to claim 41. 43. An activator comprising a water-soluble substance, an organic solvent-soluble substance, an acidic solution-soluble substance, an alkaline solution-soluble substance, a substance which forms a complex with these soluble substances, and these soluble substances at 2000 ° C. or lower. The method for producing niobium powder according to any one of claims 31 to 40, which is at least one selected from the group consisting of: 44. The activator is a metal, carbonic acid, sulfuric acid, sulfurous acid, halogen, perhalogen acid, hypohalogen acid, nitric acid,
The method for producing niobium powder according to claim 43, which is at least one selected from the group consisting of a compound with nitrous acid, phosphoric acid, or boric acid, a metal, a metal hydroxide, and a metal oxide. 45. The activator is lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, radium, scandium, yttrium, cerium, neodymium, titanium, zirconium, hafnium, vanadium, niobium. , Tantalum, molybdenum, tungsten, manganese, rhenium, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, silver, gold, zinc, cadmium, boron,
5. At least one selected from the group consisting of aluminum, gallium, indium, thallium, silicon, germanium, tin, lead, arsenic, antimony, bismuth, selenium, tellurium, polonium, and compounds thereof.
3. The method for producing niobium powder according to item 3. 46. The niobium according to any one of claims 29 to 42, wherein the activation treatment is a treatment of removing the activator by heating and / or reducing pressure before or during the sintering step. Powder manufacturing method. 47. The activation treatment is performed after the sintering step and during the crushing step,
The method for producing niobium powder according to any one of claims 29 to 40 and 43 to 45, which is a treatment of bringing a solvent into contact with the sinter or the crushed product after the crushing step to remove the activator component. . 48. The niobium powder according to claim 47, wherein the solvent is at least one selected from the group consisting of water, an organic solvent, an acidic solution, an alkaline solution, and a solution containing a ligand that forms a soluble complex. Manufacturing method. 49. The method for producing niobium powder according to claim 48, wherein the acidic solution is at least one solution selected from the group consisting of nitric acid, sulfuric acid, hydrofluoric acid, and hydrochloric acid. 50. The method for producing niobium powder according to claim 48, wherein the alkaline solution contains at least one selected from the group consisting of alkali metal hydroxides and ammonia. 51. The method for producing niobium powder according to claim 48, wherein the ligand is at least one selected from the group consisting of ammonia, glycine, and ethylenediaminetetraacetic acid. 52. The method for producing niobium powder according to claim 48, wherein the organic solvent is methyl isobutyl ketone. 53. The niobium powder according to any one of claims 1 to 7 is treated by at least one method selected from the group consisting of liquid nitriding, ion nitriding and gas nitriding methods. A method for producing niobium powder containing nitrogen. 54. The niobium powder according to any one of claims 1 to 7 is treated by at least one method selected from the group consisting of solid phase carbonization and liquid carbonization. A method for producing niobium powder containing carbon. 55. The niobium powder according to any one of claims 1 to 7 is treated by at least one method selected from the group consisting of gas boration and solid phase boration. A method for producing niobium powder containing boron. 56. Treating the niobium powder according to any one of claims 1 to 7 by at least one method selected from the group consisting of gas sulfide, ion sulfide, and solid phase sulfide. A method for producing niobium powder containing sulfur, which is characterized. 57. A niobium powder obtained by the method according to any one of claims 29 to 56. 58. A method for producing a niobium sintered body, which comprises using the niobium powder according to any one of claims 1 to 8 and 57. 59. A method of manufacturing a capacitor, comprising a niobium sintered body as one electrode, a dielectric formed on the surface of the sintered body, and a counter electrode provided on the dielectric. A method of manufacturing a capacitor, wherein the sintered body is one obtained by sintering the niobium powder according to any one of claims 1 to 8 and 57. 60. The method of manufacturing a capacitor according to claim 59, wherein the dielectric is formed by electrolytic oxidation. 61. A method of manufacturing a capacitor comprising a niobium sintered body as one electrode, a dielectric formed on the surface of the sintered body, and a counter electrode provided on the dielectric, the method comprising: A method for manufacturing a capacitor, wherein the sintered body is the niobium sintered body according to any one of claims 9 to 18. 62. An electronic circuit using the capacitor according to any one of claims 19 to 28. 63. An electronic device using the capacitor according to any one of claims 19 to 28.