JP2002008952A - Sintered body of niobium, method of manufacturing the same, and capacitor using the sintered body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sintered body of niobium, having a proper leakage current value (LC value) despite a large capacity, a method of manufacturing the sintered body, and a capacitor using the sintered body. SOLUTION: (1) A sintered body of niobium, which is obtained by sintering niobium powder, has a value of 90,000 μF.V/g or larger as the product (CV) of capacitance per unit mass (C: unit μF/g) and formation voltage (V: unit V), and a value of 5×10-4 μm-μA/(μF.V) or smaller for the quotient, obtained by dividing the product of the average particle size (D50] unit μm) of the primary particles of the niobium powder and the leakage current (LC: unit μA/g) by the CV value. (2) The method of manufacturing the sintered body of niobium is to sinter the niobium powder at a temperatures in the range of 500-2,000 deg.C, where the time for leaving it standing at the highest sintering temperature is set at 60-150 minutes, and (3) the capacitor uses the sintered body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a niobium sintered body having a good leakage current value for a large capacity, a method for producing the sintered body, and a capacitor using the sintered body.

[0002]

2. Description of the Related Art Capacitors used in electronic devices such as mobile phones and personal computers are desired to be small in size and large in capacity. Among such capacitors, tantalum capacitors are preferably used because of their large capacity for their size and good performance. A sintered body of tantalum powder is generally used as an anode body of the tantalum capacitor. In order to increase the capacity of the tantalum capacitor, it is necessary to increase the mass of the sintered body.

In the method of increasing the mass of the sintered body, the shape of the capacitor is inevitably increased, and does not satisfy the demand for miniaturization. As one of the studies for solving these drawbacks, a capacitor using a material having a higher dielectric constant than tantalum has been considered. There is niobium as a material having a large dielectric.

Japanese Patent Application Laid-Open No. 55-157226 discloses that a compact niobium powder having a particle size of 2.0 μm or less is compacted and sintered from agglomerated powder, and the molded sintered body is cut into small pieces. A method for manufacturing a sintered element for a capacitor, in which a lead portion is joined and then sintered again, is disclosed. However, this publication does not disclose the capacitor characteristics in detail.

US Pat. No. 4,084,965 discloses a capacitor using 5.1 μm niobium powder by hydrogenating and pulverizing a niobium ingot. The niobium sintered body is a tantalum sintered body. However, it is not practical because of the problem that the leakage current value is large.

The present inventors have previously proposed that the LC value can be improved by nitriding a part of niobium (Japanese Patent Laid-Open No. 10-242004; US Pat. No. 6,115,235). Further, the LC value can be reduced by, for example, increasing the sintering temperature when producing the above-mentioned niobium sintered body. However, when the sintering temperature is increased, the product of the capacity per mass of the manufactured sintered body and the formation voltage (hereinafter abbreviated as CV value) when forming a dielectric on the surface of the sintered body is reduced. Goal is high CV and low LC
It was difficult to obtain a well-balanced niobium sintered body. Further, when a capacitor is manufactured from a niobium sintered body that is conscious of only a high CV, there is a problem that a capacitor having a specifically large LC appears.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a niobium sintered body having a good leakage current value (LC value) in spite of a large capacity, a method of manufacturing the sintered body, and a sintered body thereof. It is to provide a used capacitor.

[0008]

Means for Solving the Problems As a result of diligent studies of the above-mentioned problems, the present inventors have found that a specific firing time suitable for niobium powder for capacitors is set such that the leaving time at the maximum sintering temperature of the niobium powder is a specific time. We found a knotting method and completed the present invention. That is, the present invention provides the following niobium powder sintered body, a method for producing the same, and a capacitor using the sintered body.

1. In the niobium sintered body obtained by sintering niobium powder, the product (CV) of the capacity per unit mass (C: unit μF / g) and the formation voltage (V: unit V) is 90,000 μF · V.
/ G or more, and the average particle diameter of the primary particles of the niobium powder (D
₅₀ : unit μm) and the value obtained by dividing the product of the leakage current (LC: unit μA / g) by CV is 5 × 10 ⁻⁴ μm · μA / (μF
V) A niobium sintered body that is: 2. Item 1 wherein the niobium powder is a partially nitrided niobium powder.
2. The niobium sintered body according to item 1. 3. 3. The niobium sintered body according to the above 2, wherein the nitrogen content is 20 mass ppm to 200,000 mass ppm. 4. Nitrogen content is 500 mass ppm to 7000 mass ppm
4. The niobium sintered body according to the above item 3. 5. A method for producing a niobium sintered body, comprising sintering niobium powder at a high temperature, wherein the standing time at a maximum sintering temperature at a temperature of 500 to 2000 ° C. is set to 60 to 150 minutes. Production method.

6. The method for producing a niobium sintered body according to the above item 5, wherein the standing time at the maximum sintering temperature at a temperature of 900 to 1500 ° C. is 80 to 130 minutes. 7. 7. The method for producing a niobium sintered body according to the above item 5 or 6, wherein niobium powder obtained by granulating niobium powder having an average primary particle size of 3 μm or less is used. 8. 8. The method for producing a niobium sintered body according to the above item 7, wherein niobium powder obtained by granulating niobium powder having an average primary particle diameter of 3 μm to 0.1 μm is used. 9. 9. The method for producing a niobium sintered body according to any one of the above items 5 to 8, wherein a niobium powder partially nitrided is used as the niobium powder. 10. 10. The method for producing a niobium sintered body according to the above item 9, wherein a niobium powder having a nitrogen content of 20 mass ppm to 200,000 mass ppm is used.

11. Nitrogen content is 500 mass ppm to 70
The method for producing a niobium sintered body according to the above item 10, wherein the niobium powder is used in an amount of 00 mass ppm. 12. A capacitor comprising the niobium sintered body according to any one of the above items 1 to 4 as one electrode, a dielectric formed on the surface of the sintered body, and the other electrode provided on the dielectric. . 13. 13. The capacitor according to the above item 12, wherein the dielectric comprises niobium oxide formed by electrolytic oxidation. 14． 13. The capacitor according to the above item 12, wherein the other electrode is at least one material selected from an electrolytic solution, an organic semiconductor, and an inorganic semiconductor.

15. The other electrode is made of an organic semiconductor, the organic semiconductor is an organic semiconductor consisting of benzopyrroline tetramer and chloranil, an organic semiconductor mainly containing tetrathiotetracene, an organic semiconductor mainly containing tetracyanoquinodimethane, And the following general formula (1) or (2)

Embedded image (Wherein, R ^{1 to} R ⁴ may be the same or different and each represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and X represents oxygen R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and is present only when X is a nitrogen atom, and R ¹ and R ² and R ³ and R ⁴ are bonded to each other. At least one organic semiconductor selected from the group consisting of organic semiconductors mainly composed of a conductive polymer doped with a dopant in a polymer containing two or more repeating units represented by the following formula: Item 15. The capacitor according to item 14, above. 16. Item 16. The capacitor according to item 15, wherein the organic semiconductor is at least one selected from polypyrrole, polythiophene, and substituted derivatives thereof.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment for obtaining a sintered body of the present invention will be described. Niobium powder as a raw material for producing a sintered body has an average primary particle size of 3 μm or less, preferably 3 μm to 0.1 μm, or an average particle size of 1 μm or less, preferably 1 μm to 0.1 μm. A range of 1 μm is preferred. If the average particle size exceeds 3 μm, it is difficult to obtain a sintered body having high CV characteristics and low LC characteristics, which is one of the objects of the present invention.

[0014] Here, the average particle diameter of the niobium powder, the particle size distribution measuring instrument (trade name "Microtrac") measured D ₅₀ value using (particle size value which cumulative mass% corresponds to 50 mass%) Can be adopted. Niobium powder having such an average particle size can be obtained, for example, by a method of reducing potassium fluoride niobate with sodium, or a method of pulverizing and dehydrogenating a hydride of a niobium ingot, or a method of producing niobium oxide by carbon reduction. Obtainable. For example, in the case of a method of pulverizing and dehydrogenating a hydride of a niobium ingot, it is possible to obtain a niobium powder having a desired average particle size by controlling a hydrogenation amount of the niobium ingot and a pulverization time by a pulverizer or the like. it can.

[0015] The niobium powder of the present invention is a powder having the above average particle diameter, and is preferably a partially nitrided niobium powder. In that case, the nitrogen content is 20 mass ppm
To 200,000 mass ppm (hereinafter, mass ppm is simply abbreviated to ppm).

Next, when a sintered body is prepared from the niobium powder, and a dielectric is formed on the surface of the sintered body as described later and the LC value is measured in an aqueous phosphoric acid solution, a small LC value is obtained. The nitrogen content is between 500 ppm and 7000 ppm,
In order to obtain a niobium sintered body having a good leakage current (LC) value in spite of a large capacity, 500 ppm to 4000 ppm.
Is preferable. Here, the nitrogen content is not the one adsorbed on the niobium powder or the one simply physically doped but chemically nitrided.

The nitriding of the niobium powder can be carried out by any of a liquid nitriding method, an ion nitriding method, a gas nitriding method, etc., or a combination thereof. Of these, the gas nitriding method of niobium powder, which is performed in a nitriding gas atmosphere in which the apparatus is simple and easy to operate, is preferable. This gas nitriding method can be performed, for example, by leaving the niobium powder in a nitrogen atmosphere. At this time, the nitriding atmosphere temperature is 2000 ° C. or less, and the leaving time is 60 hours or less, so that niobium powder having a desired nitrogen content can be obtained.
Further, by performing this processing at a high temperature, the processing time can be shortened. The nitrogen content of the niobium powder can be easily controlled by measuring the nitriding temperature and the nitriding time in preliminary experiments after measuring the particle size of the nitride.

The niobium powder of the present invention may be used after granulating the above-mentioned niobium powder into an appropriate shape, or may be used by mixing an appropriate amount of ungranulated niobium powder after granulation. . As the granulation method, a conventionally known method can be employed. For example,
A method in which ungranulated niobium powder is left under high temperature vacuum to be integrated (agglomerated and solidified) and then crushed, or a method in which a specific binder and ungranulated niobium powder are mixed and then crushed is used. . At this time, when kneading the niobium powder and the binder, a solvent may be used in some cases. In this case, a method of drying and disintegrating after kneading is adopted. Generally, polyvinyl alcohol, acrylic resin, or the like is used as the binder. As the solvent, those selected from acetone, alcohols, esters such as butyl acetate, water and the like can be used. The niobium granulated product thus granulated has an average particle size of 300 μm or less, preferably 200 μm.
m, more preferably 200 μm to 1 μm.

Next, a sintered body using the niobium powder of the present invention can be manufactured by sintering the above-described niobium powder. For example, as one method of manufacturing a sintered body, after pressing niobium powder into a predetermined shape, 1.33 × 10 ⁻⁴ to
500 ° C. to 200 at 1.33 × 10 ² Pa (Pascal)
0 ° C., preferably in the range of 900 ° C. to 1500 ° C., and the standing time of the niobium sintered body at the maximum sintering temperature is 60 to 15 hours.
Heat to 0 minutes, preferably 80-130 minutes.

Here, the maximum sintering temperature of the niobium sintered body means the maximum temperature under sintering conditions. The maximum sintering temperature is within the range of the temperature control fluctuation range of the sintering equipment (± 25 ° C) and the maximum set temperature ± 50 ° C.
The temperature may be a temperature obtained by a method of spontaneously controlling the temperature into a shape such as a triangular wave.

The lower limit of the sintering temperature of niobium powder is niobium.
Changes depending on the average particle size of the powder, for example, when the average particle size is small
The lower the temperature, the lower the niobium powder. On the other hand, the average
When the sintering temperature is changed, the sintering temperature is usually low.
Although the CV value of the sintered body produced by
The value is large, and it can withstand practical use as a capacitor material
Is difficult. However, in the present invention
Is the storage time at the maximum sintering temperature even if the sintering temperature is low.
From 60 to 1 suitable for obtaining a niobium sintered body for a capacitor.
50 minutes, preferably 80-130 minutes,
CV value of at least 90,000 μF · V / g or more, low LC,
That is, LC taking into account the average particle size of niobium powder and the CV value
Scale of D₅₀・ LC / CV value is 5 × 10 ^-Fourμm ・ μA /
(ΜF · V) or less.

Generally, the LC / CV value is L / surface area.
Although the C value is expressed, it is expected that even if the surface area is the same, if the particle size of niobium constituting the sintered body is different, the surface shape is different and the LC value is changed. The aforementioned measure of LC, D ₅₀
・ LC / CV value is LC considering such surface shape
Is a measure of The LC scale is 5 × 10 ⁻⁴ μm · μA /
When a capacitor is manufactured from a sintered body exceeding (μF · V), a capacitor having a specifically large LC may appear, which is not preferable.

Even if the leaving time at the maximum sintering temperature is set to less than 60 minutes or more than 150 minutes, the desired high capacity and low LC niobium sintered body cannot be obtained. Next, the manufacture of the capacitor element will be described. The capacitor element of the present invention includes the above-mentioned niobium sintered body as one electrode, a dielectric formed on the surface thereof, and the other electrode provided on the dielectric.

First, 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 formed into a compact by pressing the niobium powder. The lead wire is integrally molded so as to be inserted therein, and the lead wire is designed and assembled so as to be a lead lead of the sintered body. Here, a preferable example of the dielectric of the capacitor includes a dielectric made of niobium oxide.

Note that niobium oxide used in the present invention is a general term for niobium oxide, and the number of bonds of oxygen (O) to niobium element is not limited. For example, Nb ₂ O ₅ , N
An oxide containing bO ₂ and NbO _x (x is in the range of 1.0 to 2.5) is exemplified.

A dielectric composed of niobium oxide can be easily obtained by forming a niobium sintered body, which is one of the electrodes, in an electrolytic solution. The formation of a niobium electrode in an electrolytic solution is usually performed using a protonic acid aqueous solution, for example, a 0.1% phosphoric acid aqueous solution or a sulfuric acid aqueous solution. When a niobium electrode is formed in an electrolytic solution to obtain a dielectric composed of niobium oxide, the capacitor of the present invention becomes an electrolytic capacitor, and the niobium side becomes an anode.

The other electrode of the capacitor of the present invention is not particularly limited. For example, at least one material (compound) selected from an electrolytic solution, an organic semiconductor, and an inorganic semiconductor known in the aluminum electrolytic capacitor industry can be preferably used. Specific examples of the electrolyte include a mixed solution of dimethylformamide and ethylene glycol in which 5% by mass of an isobutyltripropylammonium borotetrafluoride electrolyte is dissolved, and a mixture of propylene carbonate and ethylene glycol in which 7% by mass of tetraethylammonium borotetrafluoride is dissolved. A mixed solution is exemplified.

Specific examples of the organic semiconductor include an organic semiconductor composed of a benzopyrroline tetramer and chloranil, an organic semiconductor composed mainly of tetrathiotetracene, an organic semiconductor composed mainly of tetracyanoquinodimethane, and the following general formula: (1) or (2)

Embedded image (Wherein, R ^{1 to} R ⁴ may be the same or different and each represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and X represents oxygen R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and is present only when X is a nitrogen atom, and R ¹ and R ² and R ³ and R ⁴ are bonded to each other. The polymer containing two or more repeating units represented by the formula (1) may be an organic semiconductor containing a conductive polymer doped with a dopant as a main component. Known dopants can be used without limitation as the dopant.

Examples of the polymer containing two or more repeating units represented by the formula (1) or (2) include, for example, polyaniline, polyoxyphenylene, poniphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and polymethylpyrrole. Examples include substituted derivatives and copolymers. Among them, polypyrrole, polythiophene and substituted derivatives thereof (for example, poly (3,4-ethylenedioxothiophene) and the like) are preferable.

Specific examples of the inorganic semiconductor include an inorganic semiconductor composed mainly of lead dioxide or manganese dioxide, and an inorganic semiconductor composed of triiron tetroxide. Such semiconductors may be used alone or in combination of two or more.

When an organic semiconductor and an inorganic semiconductor having an electric conductivity in the range of 10 ⁻² S · cm ⁻¹ to 10 ³ S · cm ⁻¹ are used, the impedance value of the produced capacitor becomes smaller, and high-frequency Can be further increased. When the other electrode is solid, a conductor layer may be provided thereon to improve electrical contact with an external lead (for example, a lead frame).

The conductor layer can be formed, for example, by solidifying a conductive paste, plating, depositing a metal, forming a heat-resistant conductive resin film, or the like. As the conductive paste, a silver paste, a copper paste, an aluminum paste, a carbon paste, a nickel paste, and the like are preferable, but one or more of these may be used. When two or more kinds 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 be solidified. Examples of plating include nickel plating, copper plating, silver plating, and aluminum plating. Examples of the metal to be deposited include aluminum, nickel, copper, and silver.

Specifically, for example, an aluminum 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 a niobium or tantalum lead sintered integrally with the niobium sintered body or later welded. The capacitor of the present invention having the above-described configuration can be used as a capacitor product for various applications by, for example, a resin mold, a resin case, a metal outer case, resin dipping, and an outer case made of a laminate film.

When the other electrode is a liquid, the capacitor formed by the electrodes and the dielectric is housed in, for example, a can electrically connected to the other electrode to form a capacitor. In this case, the electrode side of the niobium sintered body is designed so as to be led out to the outside through the niobium or tantalum lead and to be insulated from the can by insulating rubber or the like. When a capacitor is manufactured using the niobium sintered body manufactured according to the present invention described above, a capacitor having a large capacity and a good leakage current can be obtained.

[0035]

EXAMPLES The present invention will now be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In each example, the powder nitrogen content, the capacity of the sintered body, the measurement of the leakage current value (LC value) of the sintered body, and the capacity of the capacitor processed into the chip were measured by the following methods.

(1) Nitrogen Content of Powder The nitrogen content of the powder is determined using an oxygen nitrogen content measuring device manufactured by LECO, which determines the nitrogen content from the thermal conductivity, and the ratio to the mass of the powder separately measured is calculated. The nitrogen content was taken.

(2) Capacity of Sintered Body A chemical formed in a 0.1% phosphoric acid aqueous solution at 80 ° C. for 200 minutes to form a dielectric on the surface, and then immersed in a 30% sulfuric acid aqueous solution at room temperature. An LCR measuring device made by HP (LCR meter made by Hewlett-Packard Company) was connected between the electrode and the tantalum material electrode put in the sulfuric acid solution, and the measurement was performed.
The capacity at 0 Hz was defined as the capacity of the sintered body.

(3) Leakage current value (LC value) of the sintered body After forming the dielectric as described in (2) above, the sintered body immersed in a 20% phosphoric acid aqueous solution at room temperature The current value measured after continuously applying a DC voltage of 70% of the formation voltage at the time of producing the dielectric material for 3 minutes between the electrode placed in the acid aqueous solution and the leakage current value of the sintered body did.

(4) Capacitance of Capacitor Processed into Chip A value at room temperature of 120 Hz measured by an HP LCR measuring instrument, and a leakage current value at that time is measured after a rated voltage is continuously applied for one minute. Current value. In each of the following examples, the values of CV and LC indicate average values measured for 20 elements in each example.

[0040]Examples 1-3 and Comparative Examples 1-4:Difluoride
Average particle size 1μ obtained by reducing sodium potassium in sodium
m of niobium powder at 1050 ℃, 1.33 × 10^-Four2 under vacuum of Pa
After standing for 0 minutes, crushed and granulated powder with an average particle size of 150 μm
And Release the granulated powder in a nitrogen stream at 300 ° C for 1.5 hours.
Nitrogen with a nitrogen content of 1600 mass ppm
Powder. The niobium powder is a 0.3 mmφ niobium lead wire.
And a compact of 1.8 × 3.5 × 4.5 mm
Oblead wire is 3.5mm inside the molded body and 6mm outside
Is present). A plurality of such compacts (20 × 1
8) prepared, maximum sintering temperature 1150 ℃, 1.33 × 10 ^-FourPa
For the time shown in Table 1 to obtain a sintered body. Then, 0.
Forming in 1% phosphoric acid aqueous solution at 80 ° C, 20V, 200 minutes
To form a niobium oxide dielectric on the sintered body
did.

CV value, LC value and D ₅₀ · LC of each sintered body
/ CV is shown in Table 1. In addition, lead acetate 30
A mixture of equal amounts of a 30% aqueous solution and a 30% aqueous solution of ammonium persulfate was contacted 20 times at 40 ° C. to form a mixture of lead dioxide and lead sulfate (97% by mass of lead dioxide) as the other electrode. Subsequently, a carbon paste and a silver paste were sequentially laminated on the other electrode and sealed with an epoxy resin to produce a capacitor. The capacitance of the capacitor (size 7.3 mm x 4.3 mm x 2.8 mm) prepared in Table 3, 6.3 V
The LC value at was shown. The values in each example are the average values of 20 capacitors in each example. When the LC value was measured at 6.3 V, samples having an LC value exceeding 100 μA were omitted. The number of samples for which the LC value exceeded 100 μA was added.

Examples 4-6 and Comparative Examples 5-8: Average particle size obtained from grinding and dehydrogenation of hydride of niobium ingot
After leaving 0.7 μm niobium powder at 950 ° C. under a vacuum of 1.33 × 10 ⁻⁴ Pa for 20 minutes, it is crushed to obtain an average particle size of 120 μm.
m of granulated powder. The granulated powder was left in a nitrogen stream at 300 ° C. for 1.5 hours to obtain a partially nitrided niobium powder having a nitrogen content of 2000 mass ppm. Subsequently, after molding was performed in the same manner as in Comparative Example 1, the maximum sintering temperature was 1050 ° C., and 1.33 × 10 ⁻⁴ Pa.
And the sintered body was obtained for the time shown in FIG. Next, Comparative Example 1
And CV value, LC value, D ₅₀ · LC / C
The V value was determined and is shown in Table 1. Further, a 10% aqueous solution of ammonium persulfate and anthraquinone sulfonic acid are placed on the dielectric.
After contacting an equal volume of a 0.5% aqueous solution with a pyrrole vapor at least five times,
The other electrode made of polypyrrole was formed. afterwards,
A capacitor was manufactured in the same manner as in Comparative Example 1. Table 3 shows various values of the capacitor.

Comparative Examples 9 to 12: Sintered bodies and capacitors were produced in the same manner as in Comparative Example 1 except that the maximum sintering temperature was as shown in Table 2. Tables 2 and 4 show various numerical values of the sintered body and the capacitor.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

A comparison between Comparative Example 1 and Comparative Examples 9 to 12 shows that although the higher the sintering temperature, the better the LC value,
It can be seen that the V value decreases and the capacity of the manufactured capacitor sharply decreases. Those having a good balance between the LC value and the CV value, that is, L
C does not include those rubbing 100 μA and has a capacity of 400
Those having a high capacity of μF or more, as is apparent from Examples 1 to 6, set the standing time at the maximum sintering temperature to 80 to 1
Obtained as 30 minutes, CV9 10,000 or more, D ₅₀ · LC / C
It can be seen that niobium powder having a V value of 5 × 10 ⁻⁴ μm · μA / (μF · V) or less was used.

[0049]

The sintered body of niobium of the present invention has a thickness of 500 to 2
When a sintered body is produced at a temperature of 000 ° C., a standing time at a maximum sintering temperature of 60 to 150 minutes is obtained.
The product (C) of the capacity per unit mass (C) and the formation voltage (V)
V) is 90,000 μF · V / g or more, and the product of the average particle diameter (D ₅₀ ) of the primary particles of niobium powder and the leakage current (LC) is CV
Is a niobium sintered body having a value of 5 × 10 ⁻⁴ μm · μA / (μF · V) or less. The capacitor manufactured from the niobium sintered body of the present invention has a very good balance between the capacitance and the LC, and is a highly reliable capacitor.

Claims (16)

[Claims] In a niobium sintered body obtained by sintering niobium powder, a product (CV) of a capacity per unit mass (C: unit μF / g) and a formation voltage (V: unit V) is 90,000 μF.・ V /
g and the average particle diameter of primary particles of niobium powder (D ₅₀ : unit μm) and leakage current (LC: unit μA / g)
Is 5 × 10 ^-4 μm · μA /
(ΜF · V) or less niobium sintered body. 2. The niobium sintered body according to claim 1, wherein the niobium powder is a partially nitrided niobium powder. 3. The niobium sintered body according to claim 2, wherein the nitrogen content is 20 mass ppm to 200,000 mass ppm. 4. The nitrogen content is from 500 ppm by mass to 7000.
The niobium sintered body according to claim 3, wherein the mass is ppm. 5. A method for producing a niobium sintered body for sintering niobium powder at a high temperature, comprising the steps of:
A method for producing a niobium sintered body, wherein a standing time at a maximum sintering temperature is 60 to 150 minutes. 6. The method for producing a niobium sintered body according to claim 5, wherein the standing time at the maximum sintering temperature is set to 80 to 130 minutes at a temperature of 900 to 1500 ° C. 7. A niobium powder obtained by granulating niobium powder having an average primary particle size of 3 μm or less.
3. The method for producing a niobium sintered body according to item 1. 8. The primary particles have an average particle size of 3 μm to 0.1 μm.
8. A niobium powder obtained by granulating niobium powder having a particle size of m.
3. The method for producing a niobium sintered body according to item 1. 9. The method for producing a niobium sintered body according to claim 5, wherein a niobium powder partially nitrided is used as the niobium powder. 10. The method for producing a niobium sintered body according to claim 9, wherein a niobium powder having a nitrogen content of 20 mass ppm to 200,000 mass ppm is used. 11. The nitrogen content is from 500 ppm by mass to 700 ppm.
The method for producing a niobium sintered body according to claim 10, wherein 0 mass ppm niobium powder is used. 12. The niobium sintered body according to claim 1 as one electrode, a dielectric formed on the surface of the sintered body, and the other electrode provided on the dielectric. And composed of a capacitor. 13. The capacitor according to claim 12, wherein the dielectric comprises niobium oxide formed by electrolytic oxidation. 14. The capacitor according to claim 12, wherein the other electrode is at least one material selected from an electrolyte, an organic semiconductor, and an inorganic semiconductor. 15. The other electrode is made of an organic semiconductor,
The organic semiconductor is an organic semiconductor composed of benzopyrroline tetramer and chloranil, an organic semiconductor composed mainly of tetrathiotetracene, an organic semiconductor composed mainly of tetracyanoquinodimethane, and the following general formula (1) or (2) ) (Wherein, R ^{1 to} R ⁴ may be the same or different and each represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and X represents oxygen R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and is present only when X is a nitrogen atom, and R ¹ and R ² and R ³ and R ⁴ are bonded to each other. At least one organic semiconductor selected from the group consisting of organic semiconductors mainly composed of a conductive polymer doped with a dopant in a polymer containing two or more repeating units represented by the following formula: The capacitor according to claim 14. 16. The capacitor according to claim 15, wherein the organic semiconductor is at least one selected from polypyrrole, polythiophene, and substituted derivatives thereof.