JP2003003204A - Method for manufacturing niobium powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing niobium powder of low oxygen content for capacitor by which a capacitor having increased capacitance per unit mass, decreased leakage current and reduced fluctuation can be obtained and also to provide a method for manufacturing a sintered compact using the niobium powder and a capacitor using the sintered compact. SOLUTION: Niobium hydride or niobium-alloy hydride is pulverized at -200 to 30 deg.C in the presence of a disperse medium to obtain the niobium powder of low oxygen content. The sintered compact for capacitor electrode and also the capacitor are constituted by using the above niobium powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing niobium powder for a capacitor, which is capable of obtaining a capacitor having a large capacity per unit mass and good leakage current characteristics by reducing the oxygen content in niobium. The present invention relates to a niobium powder for capacitors, a sintered body using the same, and a capacitor using the sintered body. Niobium for capacitors is a material that contains niobium as a main component and can be a material for manufacturing capacitors.

[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, the tantalum capacitor is preferred because it has a large capacity for its size and good performance. A sintered body of tantalum powder is generally used as the anode body of this tantalum capacitor. 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. In the method of pulverizing tantalum powder to increase the surface area, the pore size of the tantalum sintered body becomes smaller and the number of closed pores increases, so that impregnation of the catholyte in the subsequent step becomes difficult. As one of the researches for solving these drawbacks, a sintered body capacitor using a material having a larger dielectric constant than tantalum can be considered. Materials having a large dielectric constant include niobium and niobium alloys.

However, as a method for producing niobium powder for a capacitor, Japanese Patent Laid-Open No. 55-157226 discloses that a niobium powder having a particle size of 2 μm or less is formed from agglomerated powder and sintered to obtain a sintered element for a capacitor. However, the publication does not provide details on the capacitor characteristics.

US Pat. No. 4,084,965 discloses that a niobium ingot is hydrogenated and pulverized to 5.1 μm.
A capacitor obtained by obtaining niobium powder of m and sintering the niobium powder is disclosed. However, the disclosed capacitor has a large leakage current (hereinafter may be abbreviated as LC) and is not practical.

Japanese Unexamined Patent Publication (Kokai) No. 10-242004 discloses that the LC value is improved by nitriding a part of niobium powder. However, when a high-capacity capacitor is made from a niobium sintered body by using niobium powder having a fine particle size, a capacitor having a specific large LC value may appear.

[0007]

An object of the present invention is to provide a capacitor having a large capacity per unit mass, a small leakage current, and a small variation by reducing the amount of oxygen in niobium for a capacitor. It is to provide niobium powder for a capacitor, a sintered body using the same, and a method for manufacturing a capacitor using the sintered body.

[0008]

As a result of intensive studies on the above-mentioned problems, the inventors of the present invention have found that the cause of LC variation is oxygen contained in the niobium powder for capacitors, and for example, niobium hydride or niobium hydride at low temperature is used. The inventors have found that LC characteristics can be improved by using niobium powder for capacitors having a low oxygen content, obtained by crushing an alloy, and completed the present invention. That is, the present invention includes the following.

(1) In the method for producing niobium hydride for a capacitor including the step of pulverizing niobium hydride or a niobium hydride alloy in the presence of a dispersion medium, the pulverization temperature is -200 to 3
A method for producing niobium powder for a capacitor, which is in a temperature range of 0 ° C. (2) The method for producing niobium powder for capacitors according to the above item 1, which comprises a step of dehydrogenating the niobium hydride powder or the niobium hydride alloy powder at a temperature of 100 to 1000 ° C. after crushing. (3) The method for producing niobium powder for a capacitor as described in 1 or 2 above, wherein the crushing temperature does not rise during crushing. (4) The method for producing niobium powder for capacitors according to any one of the above items 1 to 3, wherein the dispersion medium is at least one selected from the group consisting of water, an organic solvent, and a liquefied gas.

(5) Niobium powder for capacitors obtained by the manufacturing method according to any one of items 1 to 4 above. (6) The average particle size of the niobium powder for capacitors is 0.01 to
The niobium powder for capacitors according to the item 5 above, which is 10 μm. (7) The BET specific surface area of the niobium powder for capacitors is 0.
The niobium powder for capacitors according to item 5 or 6 above, which has an amount of 5 to 40 m ² / g. (8) The bulk density of niobium powder for capacitors is 0.5 to 4 g.
The niobium powder for capacitors according to any one of the above items 5 to 7, which is / ml. (9) The peak of the pore size of the niobium powder for capacitors is 0.
The niobium powder for capacitors according to any one of items 5 to 8 above, which has a particle size of 01 to 7 μm. (10) The niobium powder for capacitors according to any one of the above items 5 to 9, wherein the niobium powder for capacitors has an oxygen content of 2.5 mass% or less. (11) The niobium powder for capacitors according to any one of items 5 to 10 above, wherein the niobium powder for capacitors further contains at least one element selected from the group consisting of elements of boron, nitrogen, carbon and sulfur.

(12) A niobium granulated product for capacitors having an average particle size of 10 to 500 μm obtained by granulating the niobium powder for capacitors described in any one of the above items 5 to 11. (13) The niobium granulated product for capacitors according to the above item 12, wherein the BET specific surface area of the niobium granulated product for capacitors is 0.5 to 40 m ² / g. (14) The above-mentioned item 12 or 1, wherein the peak of the pore diameter of the niobium granulated product for capacitors is in the range of 0.01 to 500 μm.
3. A niobium granulated product for capacitors according to 3. (15) The bulk density of the niobium granulated product for capacitors is 0.0
The niobium granulated product for capacitors according to any one of the above items 12 to 14, which is 5 to 4 g / ml. (16) The niobium granulated product for capacitors according to any one of the above items 12 to 15, wherein the niobium granulated product for capacitors has an oxygen concentration of 3% by mass or less.

(17) Obtained by sintering the niobium powder for capacitors according to any one of the above 5 to 11 and / or the granulated niobium for capacitors according to any one of the above 12 to 16 Sintered body. (18) A capacitor comprising the sintered body according to the item 17 as one electrode, and a dielectric formed on the surface of the sintered body and the other electrode provided on the dielectric. (19) The capacitor as described in 18 above, wherein the main component of the dielectric is niobium oxide.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

It is a known technique to hydrogenate a niobium ingot and to grind it using a suitable grinder in the presence of a suitable dispersion medium (US Pat. No. 4,084,965).
However, when niobium powder for a capacitor is manufactured by using these methods, the LC value is high and the variation is large, so that the capacitor is not reliable. This is
Oxygen present in the dispersion medium reacts or adsorbs with niobium hydride due to the heat generated during pulverization, and is then crystallized into niobium oxide when producing a sintered body, which is thought to have a particularly bad effect on LC. To be Therefore, it is important to suppress the amount of oxygen in the niobium hydride powder to be low in order to improve LC characteristics. In order to keep the amount of oxygen in the niobium hydride powder low, for example, there is a method of suppressing the temperature rise during grinding. The same applies to the niobium hydride alloy powder.

In the present invention, -200 in the presence of a suitable dispersion medium.
By crushing niobium hydride or a niobium hydride alloy in a temperature range of -30 ° C., for example, a niobium hydride powder or a niobium hydride alloy powder having a low oxygen content and capable of obtaining a capacitor having good LC characteristics can be obtained. Can be made. Of the above temperature ranges, the lower the oxygen content and the lower the temperature range that has the effect of improving the LC value, the better. However, pulverization at extremely low temperatures is expensive because the pulverization equipment is too large. Therefore, -40-10 degreeC is especially preferable. Not raising the temperature during milling is preferred to prevent an increase in the oxygen content of the mill. Therefore, it is more preferable to keep the temperature during pulverization constant or to lower it in the temperature range of −200 to 30 ° C.

As the dispersion medium, for example, water, an organic solvent,
Alternatively, a liquefied gas or the like can be preferably used, and when these dispersion media are used, it is preferable to perform sufficient degassing before use. As the organic solvent, alcohols, ethers, cellosolves, esters, aliphatic hydrocarbons, halogenated hydrocarbons and the like can be preferably used. Furthermore, a dispersion medium that does not solidify at the crushing temperature is preferable. Liquid nitrogen and liquid argon are preferable as the liquefied gas.

Examples of the raw material of the niobium powder for capacitors of the present invention include niobium and / or niobium alloy. As alloy components other than niobium of this niobium alloy, lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, radium, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, Europium, gadolinium, terbium, dysprosium, holmium, erbium, vanadium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc,
Cadmium, mercury, boron, aluminum, gallium,
Indium, thallium, carbon, silicon, germanium, tin, lead, phosphorus, arsenic, antimony, bismuth, selenium,
At least one selected from the group consisting of tellurium, polonium, and astatine can be given.

As the crusher, for example, a bead mill is suitable as a crusher using a crushing medium. Examples of the material of the grinding medium include stainless steel, zirconia, niobium, ZTA (alumina reinforced zirconia), alumina and the like, and zirconia and niobium are particularly preferable.

The obtained niobium hydride powder or niobium hydride alloy powder can be obtained as a powder by drying the pulverized product using a known drying method. The powder thus obtained usually has an average particle size of 0.01 to 10
μm, BET specific surface area of 0.5 to 40 m ² / g, bulk density of 0.5 to ⁴ g / ml, and pore diameter peak of 0.01.
Is in the range of ~ 7 μm.

The oxygen content of the niobium hydride powder or niobium hydride alloy powder of the present invention thus obtained is usually 5000.
Although it is 0 ppm or less, in order to further improve the LC characteristics, it is preferably in the range of 2000 to 25000 ppm. The oxygen amount used in the present invention is a value measured using EGMA-620W manufactured by Horiba Ltd.,
When the slurry is directly measured, the value obtained by converting the slurry concentration into dry powder is shown.

The niobium hydride powder or hydrogenated alloy powder of the present invention may be directly sintered to produce a sintered body, or 1
Dehydrogenation may be performed at a temperature of 00 to 1000 ° C. and used as niobium powder or niobium alloy powder. Further, in order to improve the leakage current value of these hydrogenated niobium powder, hydrogenated alloy powder, niobium powder or niobium alloy powder, a part of these niobium powders is treated by nitriding, borating, carbonizing, and sulfurizing. You may. The nitride, the boride, the carbide, and the sulfide obtained by performing the treatment by nitriding, borating, carbonizing, and sulfurizing may contain any of these, and these two kinds,
It may be a combination of three or four kinds. The amount of binding,
That is, the total content of nitrogen, boron, carbon, and sulfur varies depending on the particle size and shape of each powder, the amount of the other alloy component, and the amount of the other alloy component present, but the average particle size is 0.01 μm to 10 μm.
More than 0ppm in powder of about μm 200,000ppm
It is the following. If it exceeds 200,000 ppm, the capacitance characteristic deteriorates and it is not suitable as a capacitor. From the viewpoint of LC and capacity optimization, 50 ppm to 10,000 ppm is preferable, and 200 ppm to 20,000 ppm is particularly preferable.

The hydrogenated niobium powder for capacitors, hydrogenated alloy powder, niobium powder or niobium alloy powder of the present invention may be granulated into an appropriate shape and then used, or ungranulated niobium powder after granulation. You may mix and use a suitable amount.

As the granulation method, for example, a method in which ungranulated niobium powder which is partially nitrided is left under a high reduced pressure, heated to an appropriate temperature and then crushed, camphor, polyacrylic acid, polymethylacryl A method in which a suitable binder such as acid ester or polyvinyl alcohol is mixed with a solvent such as acetone, alcohol, acetate, water or the like and ungranulated or granulated partially nitrified niobium powder and then crushed Etc. This method can also be suitably used for hydrogenated niobium powder, niobium powder, hydrogenated niobium alloy powder, and niobium alloy powder.

The niobium granules or niobium alloy granules granulated in this manner improve the press moldability when producing a sintered body. In this case, the average particle size of the granulated powder is 10 μm
˜500 μm is preferred. The average particle size of the granulated powder is 10 μm
In the following, blocking will occur partially and the fluidity to the mold will deteriorate. If the thickness is 500 μm or more, the molded body after pressure molding tends to chip. Further, after sintering the pressure-molded body, it is easy to impregnate the cathodic agent when manufacturing the capacitor,
The average particle size of the granulated product is particularly preferably 30 μm to 250 μm. Usually, the BET specific surface area of the granules thus obtained is 0.5 to 40 m ² / g, and the bulk density is 0.5.
~ 4g / ml, peak of pore size is 0.01 ~ 500μ
m, the oxygen content is 5% by mass or less.

The niobium sintered body for a capacitor or the niobium alloy sintered body of the present invention is manufactured by sintering the above powder or the above granulated material. The method for producing the sintered body is not particularly limited, but for example, a lead wire made of a valve metal such as niobium or tantalum and having an appropriate shape and length is prepared. During the pressure molding of the granulated powder, the lead wire is integrally molded so that a part of the lead wire is inserted into the inside of the molded body, and the lead wire is assembled and designed so as to be a lead for the sintered body. After the above-mentioned powder or the above-mentioned granulated material is pressure-molded into a predetermined shape, it is heated at 10 ^-5 to 10 ² Pa for 1 minute to 10 hours, 500 ° C to 2000 ° C, preferably 900 ° C to 15
A niobium sintered body for a capacitor or a niobium alloy sintered body can be obtained by heating at 00 ° C, more preferably in the range of 900 ° C to 1300 ° C.

A capacitor can be manufactured by using the above-mentioned sintered body as one electrode and a dielectric material interposed between the other electrodes. Here, as the dielectric of the capacitor, a dielectric containing niobium oxide as a main component is preferable. The dielectric containing niobium oxide as a main component is obtained, for example, by forming a niobium sintered body, which is one of the electrodes, in an electrolytic solution. To form a niobium electrode in an electrolytic solution, a protonic acid aqueous solution is usually used, for example, a 0.1 mass% phosphoric acid aqueous solution,
It is performed using a sulfuric acid aqueous solution, a 1 mass% acetic acid aqueous solution, an adipic acid aqueous solution, or the like. When a niobium electrode is formed in an electrolytic solution to obtain a niobium oxide dielectric, the capacitor of the present invention serves as an electrolytic capacitor and the niobium electrode serves as an anode.

In the capacitor of the present invention, the other electrode (counter electrode) of the niobium sintered body is not particularly limited and is selected from, for example, electrolytic solutions, organic semiconductors and inorganic semiconductors known in the aluminum electrolytic capacitor industry. At least one material (compound) 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. An example of the conductive polymer includes a repeating unit represented by the formula (1) or the general formula (2).

[0030]

[Chemical 1]

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, and R ⁵
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.

Further, in the present invention, R ^{1 to} R ⁴ in the general formula (1) or the general formula (2) are preferably
Each independently represents a hydrogen atom, a linear or branched saturated or unsaturated alkyl group or alkoxy group having 1 to 6 carbon atoms, and R ¹ and R ² and R ³ and R ⁴ are bonded to each other to form a ring. May be.

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.

[0034]

[Chemical 2]

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 with respect to each other. 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.

The conductive polymer containing such a chemical structure is charged and doped with a dopant. Known dopants can be used as the dopant without limitation. Specific examples of the inorganic semiconductor include an inorganic semiconductor having lead dioxide or manganese dioxide as a main component, an inorganic semiconductor made of ferric tetroxide, and the like. Such semiconductors may be used alone or in combination of two or more.

Examples of the polymer containing a repeating unit represented by the general formula (1) or the general formula (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 preferred.

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

As the method for producing the conductive polymer layer, for example, aniline, thiophene, furan, pyrrole,
A method is employed 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. 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 a polymerization process operation,
By repeating the niobium sinter having the dielectric once or more, preferably 3 to 20 times, a dense and layered conductive polymer layer can be easily formed.

In the method of manufacturing 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 (anion other than the reducing anion of an oxidizing agent) having a dopant ability to coexist as necessary is
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 sulfonate anion such as p-toluenesulfonic acid, naphthalenesulfonic acid, or an alkyl-substituted naphthalenesulfonic acid having 1 to 5 carbon atoms, CF ₃ SO ₃ ⁻ , C
H ₃ SO ₃ ^-, such as organic sulfonic acid anion or CH _3,
Proton acid anions such as carboxylic acid anions such as COO ⁻ and C ₆ H ₅ COO ⁻ can be mentioned.

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.

Among the organic sulfonate anions, more effective dopants include sulfoquinone compounds having one or more sulfoanion groups (—SO ₃ —) and a quinone structure in the molecule, and anthracene sulfonate anions. 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 other 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. If two or more are used, they may be mixed or stacked as separate layers. After applying the conductive paste, leave it in the air or heat it to solidify. Examples of the plating include nickel plating, copper plating, silver plating, aluminum plating and the like. Further, examples of the vapor deposition metal include aluminum, nickel, copper, silver and the like.

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 niobium or tantalum leads that are sintered together with the niobium sinter or are later 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 other electrode is liquid, the capacitor formed of the both electrodes and the dielectric is housed in, for example, a can electrically connected to the other electrode to form the capacitor. In this case, the electrode side of the rhenium-containing 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 hydride powder, a niobium hydride alloy powder, a niobium powder, a niobium alloy powder produced according to the embodiment of the present invention and a granulated product thereof are used to produce a sintered body for a capacitor. By manufacturing a capacitor from the sintered body, a highly reliable capacitor having a small leakage current value can be obtained.

[0054]

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. In each example, a sintered body prepared from the above-mentioned powder or granulated material having desired physical properties (hereinafter abbreviated as “niobium sintered body”, “niobium alloy sintered body” or simply “sintered body”). .) And the leakage current value of the chip-processed capacitor, and the leakage current value were measured by the following methods.

(1) Measurement of Capacity of Sintered Body At room temperature, the sintered body having the dielectric layer formed thereon and the electrode of the tantalum material were immersed in 30% by mass of sulfuric acid, and each of them was measured by a Hewlett Packard measuring instrument ( Precision LC
R meter HP4284A type) and the capacity at 120 Hz was measured. This measured value per mass of the sintered body was defined as the capacity of the sintered body (unit is μF · V / g).

(2) Leakage Current Measurement of Sintered Body A sintered body having a dielectric layer formed as an anode and a cathode were immersed in a 20 mass% phosphoric acid aqueous solution at room temperature, and a direct current of 14 V was applied for 3 minutes. After continuing, the current value was measured.
This measured value per mass of the sintered body was taken as the leakage current value (LC value, unit: μA / g) of the sintered body.

(3) 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 measured value of the capacitance at 120 Hz was taken as the capacitance of the chip-processed capacitor.

(4) Leakage Current Measurement of Capacitor At room temperature, a DC voltage of 6.3 V was continuously applied between the terminals of the fabricated chip for 1 minute, and then the measured leakage current value of the capacitor processed into the chip was measured. And

(5) Particle size measurement For Microtrac HRA 9320-X100
The particle size distribution was measured by the laser diffraction scattering method. That accumulation
Volume% corresponds to a particle size value (D ₅₀; Μm)
Was defined as the average particle size.

Example 1: 1000 g of niobium ingot was placed in a reaction vessel made of SUS304, and hydrogen was continuously introduced at 400 ° C. for 10 hours. After cooling to room temperature, the hydrogenated niobium lump was coarsely crushed with a hammer crusher in an argon atmosphere to obtain a niobium hydride coarse powder having a particle size of 0.5 mm or less. Then, using zirconia beads having a particle diameter of 1 mm as a grinding medium and degassed methanol as a dispersion medium, the niobium hydride coarse powder was wet ground for 6 hours while cooling from a grinding temperature of 10 ° C to -40 ° C. A methanol slurry of niobium hydride powder was obtained. Dried under reduced pressure at 40 ℃,
A niobium hydride powder was obtained. The average particle size of this powder is 0.9μ
m and the oxygen concentration was 1.2% by mass. The niobium hydride powder thus obtained was heated at 1 × 10 ^-2 Pa and 400 ° C. for 4 hours for dehydrogenation, and then cooled to room temperature. Nitrogen was introduced under atmospheric pressure and nitriding was performed at 300 ° C. for 2 hours. The niobium powder thus obtained was treated under reduced pressure of 4 × 10 ⁻³ Pa to obtain 11
After sintering at 00 ° C. for 2 hours, it was cooled to room temperature. The obtained niobium lump was crushed to obtain niobium granulated powder. The average particle size of this granulated powder was 110 μm, and the oxygen content was 1.
It was 8% by mass.

The niobium granulated powder thus obtained was 0.3
Molded together with mmφ niobium wire, approximately 0.3 cm ×
A 0.18 cm × 0.45 cm molded body (about 0.1 g) was produced. Next, these molded bodies were left under reduced pressure of 4 × 10 ⁻³ Pa at 1250 ° C. for 30 minutes to obtain a sintered body. The obtained sintered body was subjected to chemical conversion in a 0.1 mass% phosphoric acid aqueous solution at a temperature of 80 ° C. for 6 hours at a voltage of 20 V to form a dielectric layer on the surface. Then, the capacity in 30 mass% sulfuric acid and the leak current in 20 mass% phosphoric acid aqueous solution were measured. The results are shown in Table 1.

Examples 2 to 5: In the same manner as in Example 1, niobium powder was produced by changing the dispersion medium and the temperature at the time of pulverization, and then granulated powder was produced.

The niobium granulated powder thus obtained was molded together with a niobium wire having a diameter of 0.3 mm to obtain about 0.3 c
m × 0.18 cm × 0.45 cm molded body (about 0.1
g) was prepared. Next, these molded bodies were treated with 4 × 10 ⁻³ Pa
A sintered body was obtained by leaving it under reduced pressure at 1250 ° C. for 30 minutes. The obtained sintered body was subjected to chemical conversion in a 0.1 mass% phosphoric acid aqueous solution at a temperature of 80 ° C. for 6 hours at a voltage of 20 V to form a dielectric layer on the surface. After this, 3
The capacity in 0 mass% sulfuric acid and the leakage current in 20 mass% phosphoric acid aqueous solution were measured. The results are shown in Table 1.

Examples 6 to 16: 1000 g of various niobium alloy ingots were placed in a reaction container made of SUS304 and 40
Hydrogen was continuously introduced at 0 ° C. for 10 hours. After cooling to room temperature, under argon atmosphere, the hydrogenated niobium alloy lump,
Coarse crushing with hammer crusher, particle size 0.5mm
The following coarse powder was obtained. Then, using zirconia beads having a particle diameter of 1 mm as a grinding medium and degassed ethanol as a dispersion medium, the niobium hydride coarse powder is wet for 6 to 10 hours while cooling from a grinding temperature of 10 ° C to -30 ° C. It was pulverized to obtain an ethanol slurry of niobium hydride alloy powder. It was dried at 40 ° C. under reduced pressure to obtain a niobium hydride alloy powder.
The niobium hydride alloy powder obtained in this manner was added to 1 × 10 ^-2 P
After heating at 400 ° C. for 4 hours for dehydrogenation, sintering was further performed at 1100 ° C. for 2 hours under reduced pressure of 4 × 10 ⁻³ Pa, and then cooled to room temperature. The obtained niobium alloy lump was crushed to obtain niobium alloy granulated powder.

The obtained niobium granulated powder was molded together with a niobium wire having a diameter of 0.3 mm to obtain a powder of about 0.3 cm × 0.18 c
A m × 0.45 cm molded body (about 0.1 g) was produced.
Next, these molded bodies were subjected to 125 × 10 ⁻³ Pa under a reduced pressure of 125
A sintered body was obtained by leaving it at 0 ° C. for 30 minutes. The obtained sintered body was subjected to chemical conversion in a 0.1 mass% phosphoric acid aqueous solution at a temperature of 80 ° C. for 6 hours at a voltage of 20 V to form a dielectric layer on the surface. Then, the capacity in 30 mass% sulfuric acid and the leak current in 20 mass% phosphoric acid aqueous solution were measured. The results are shown in Table 1.

Comparative Example 1: 1000 g of niobium ingot was placed in a reaction vessel made of SUS304, and hydrogen was continuously introduced at 400 ° C. for 10 hours. After cooling to room temperature, the hydrogenated niobium lump was coarsely crushed with a hammer crusher under an argon atmosphere to obtain coarse powder having a particle size of 0.5 mm or less.
Next, using zirconia beads having a particle diameter of 1 mm as a grinding medium and degassed ethanol as a dispersion medium, a grinding temperature of 40 ° C.
While raising the temperature to 70 ° C. from 70 to 70 ° C., the niobium hydride coarse powder was wet pulverized for 6 hours to obtain an ethanol slurry of niobium hydride powder. It was dried at 40 ° C. under reduced pressure to obtain niobium hydride powder. The average particle diameter of this powder was 0.9 μm, and the oxygen concentration was 6.3 mass%. The niobium hydride powder thus obtained was heated at 1 × 10 ^-2 Pa and 400 ° C. for 4 hours for dehydrogenation, and then cooled to room temperature. Nitrogen was introduced under atmospheric pressure and nitriding was performed at 300 ° C. for 2 hours. Further, the niobium powder was sintered under reduced pressure of 4 × 10 ⁻³ Pa at 1100 ° C. for 2 hours and then cooled to room temperature. The obtained niobium lump was crushed to obtain niobium granulated powder. The average particle size of this granulated powder is 110
μm, and the oxygen content was 6.8% by mass.

The niobium granulated powder thus obtained was molded together with a 0.3 mmφ niobium wire to obtain about 0.3 c
m × 0.18 cm × 0.45 cm molded body (about 0.1
g) was prepared. Next, these molded bodies were treated with 4 × 10 ⁻³ Pa
A sintered body was obtained by leaving it under reduced pressure at 1250 ° C. for 30 minutes. The obtained sintered body was subjected to chemical conversion in a 0.1 mass% phosphoric acid aqueous solution at a temperature of 80 ° C. for 6 hours at a voltage of 20 V to form a dielectric layer on the surface. After this, 3
The capacity in 0 mass% sulfuric acid and the leakage current in 20 mass% phosphoric acid aqueous solution were measured. The results are shown in Table 1.

Comparative Examples 2-3: Comparative Example 2 was pulverized in the same manner as in Example 2 while maintaining the pulverizing temperature at 40 ° C.

Comparative Example 3 was pulverized in the same manner as in Example 6 by raising the pulverization temperature from -30 ° C to 10 ° C.
Thereafter, granulation and sintering were performed in the same manner as in Example 2 or Example 6, and the obtained sintered body was placed in a 0.1 mass% phosphoric acid aqueous solution at a temperature of 80 ° C. for 6 hours at 20 V. A dielectric layer was formed on the surface by chemical conversion with voltage. After this, 30
The capacity in mass% sulfuric acid and the leakage current in a 20 mass% phosphoric acid aqueous solution were measured. The results are shown in Table 1.

[0070]

[Table 1]

Examples 17-18: Example 17 is Example 1
In Example 18, 50 sintered bodies obtained by the same method as in Example 6 were prepared. 20V of these sintered bodies
At a voltage of 0.1% by mass, an aqueous solution of phosphoric acid was used for electrolytic formation for 200 minutes to form a dielectric oxide film on the surface. Next, the manganese dioxide layer was formed as the other electrode layer on the dielectric oxide film by repeating the heating at 220 ° C. for 30 minutes after immersion in a 60 mass% manganese nitrate aqueous solution. 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 average of the capacitance and LC value of this chip type capacitor (n = 50 for each)
Are shown in Table 2. The LC value is a value when 6.3 V is applied for 1 minute at room temperature.

Examples 19 to 20: Example 19 is Example 2
In Example 20, 50 sintered bodies obtained by the same method as in Example 8 were prepared. 20V of these sintered bodies
At a voltage of 0.1% by mass, an aqueous solution of phosphoric acid was used for electrolytic formation for 200 minutes to form a dielectric oxide film on the surface. Next, the operation of contacting pyrrole vapor with at least 5 times after contacting an equal amount mixed solution of 10 mass% ammonium persulfate aqueous solution and 0.5 mass% anthraquinonesulfonic acid aqueous solution on the dielectric oxide film. Thus, the other 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. Table 2 shows the average of the capacitance and LC value of this chip type capacitor (n = 50 each). The LC value is a value when 6.3 V is applied for 1 minute at room temperature.

Examples 21 to 22: Example 21 is Example 3
In Example 22, 50 sintered bodies obtained by the same method as in Example 10 were prepared. These sintered bodies were electrolyzed at a voltage of 20 V using a 0.1 mass% phosphoric acid aqueous solution for 200 minutes to form a dielectric oxide film on the surface. Next, this sintered body was immersed in an aqueous solution (solution 1) containing 25% by mass of ammonium persulfate and then pulled up and dried at 80 ° C. for 30 minutes, and then the sintered body on which a dielectric was formed was 3,4- It was immersed in an isopropanol solution (solution 2) containing 18% by mass of ethylenedioxythiophene, then 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 was performed, and
The other electrode (counter electrode) made of conductive poly (3,4-ethylenedioxythiophene) was formed by drying at 0 ° C. for 30 minutes.

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 2 shows the average of the capacitance and LC value of this chip type capacitor (n = 50 each). The LC value is a value when 6.3 V is applied for 1 minute at room temperature.

Comparative Examples 4 to 5: For Comparative Example 4, 50 sintered bodies obtained by the same method as Comparative Example 1 and Comparative Example 5 were prepared. These sintered bodies were electrolyzed at a voltage of 20 V using a 0.1 mass% phosphoric acid aqueous solution for 200 minutes to form a dielectric oxide film on the surface. Next, this niobium sintered body was immersed in an aqueous solution containing 25% by mass of ammonium persulfate (Solution 1), then pulled up and dried at 80 ° C. for 30 minutes, and then the sintered body on which a dielectric was formed was -Oxidative polymerization was carried out by immersing in an isopropanol solution (solution 2) containing 18% by mass of ethylenedioxythiophene, pulling it up, and leaving it in an atmosphere of 60 ° C for 10 minutes. This was immersed again in the solution 1 and further treated in the same manner as described above. After repeating the operation from dipping in the solution 1 to oxidative polymerization 8 times, wash with warm water at 50 ° C. for 10 minutes and then at 100 ° C.
Conductive poly (3,4)
-The other electrode (counter electrode) consisting of ethylenedioxythiophene) 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. Table 2 shows the average of the capacitance and LC value of this chip type capacitor (n = 50 each). The LC value is a value when 6.3 V is applied for 1 minute at room temperature.

[0078]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01G 9/00 H01G 9/05 K 9/052 9/24 C (72) Inventor Toshiya Kawasaki Kawasaki City, Kanagawa Prefecture 5-1 Okawa-cho, Kawasaki-ku Showa Denko Co., Ltd. Production Technology Center (72) Inventor Kazumi Naito 1-1-1, Onodai, Midori-ku, Chiba-shi, Chiba Showa Denko K.K. (72) Inventor Kazuhiro Omori 1-1-1 Onodai, Midori-ku, Chiba-shi, Chiba Showa Denko Co., Ltd. Research Institute F-term (reference) 4K017 AA03 AA04 BA07 BB13 BB15 DA08 EA03 FB02 4K018 AA40 BA20 BB04 BB10 BC01 BC10 BC11 BD10 DA00 JA09 JA12 JA16 KA39

Claims (19)

[Claims] 1. A method for producing niobium hydride for a capacitor, which comprises a step of pulverizing niobium hydride or a niobium hydride alloy in the presence of a dispersion medium, wherein the pulverization temperature is in the temperature range of −200 to 30 ° C. Manufacturing method of niobium powder for capacitors. 2. The method for producing niobium powder for capacitors according to claim 1, further comprising a step of dehydrogenating the niobium hydride powder or the niobium hydride alloy powder at a temperature of 100 to 1000 ° C. 3. The method for producing niobium powder for capacitors according to claim 1, wherein the crushing temperature does not rise during crushing. 4. The dispersion medium is at least one selected from the group consisting of water, an organic solvent, and a liquefied gas.
2. A method for producing niobium powder for capacitors according to any one of 1. 5. A niobium powder for capacitors, which is obtained by the manufacturing method according to claim 1. 6. The average particle size of the niobium powder for capacitors is 0.
The niobium powder for capacitors according to claim 5, which has a particle size of 01 to 10 μm. 7. The niobium powder for capacitors according to claim 5, wherein the niobium powder for capacitors has a BET specific surface area of 0.5 to 40 m ² / g. 8. The niobium powder for capacitors has a bulk density of 0.5.
The niobium powder for capacitors according to any one of claims 5 to 7, which has a content of ~ 4 g / ml. 9. The niobium powder for capacitors according to claim 5, wherein the niobium powder for capacitors has a peak pore size of 0.01 to 7 μm. 10. The niobium powder for capacitors according to claim 5, wherein the niobium powder for capacitors has an oxygen content of 2.5 mass% or less. 11. The capacitor according to claim 5, wherein the niobium powder for capacitors further contains at least one element selected from the group consisting of elements of boron, nitrogen, carbon and sulfur. Niobium powder. 12. A niobium granulated product for capacitors having an average particle size of 10 to 500 μm, which is obtained by granulating the niobium powder for capacitors according to any one of claims 5 to 11. 13. A BET ratio table of granulated niobium for capacitors.
Area is 0.5-40m ²/ G. 13.
Niobium granules for capacitors. 14. The peak of the pore diameter of the niobium granulated product for capacitors is in the range of 0.01 to 500 μm.
Or a niobium granulated product for a capacitor as described in 13 above. 15. The bulk density of the niobium granulated product for a capacitor is
The niobium granulated product for capacitors according to any one of claims 12 to 14, which is 0.05 to 4 g / ml. 16. The niobium granulated product for capacitors according to claim 12, wherein the niobium granulated product for capacitors has an oxygen concentration of 3% by mass or less. 17. A niobium powder for capacitors according to any one of claims 5 to 11 and / or a niobium granule for capacitors according to any one of claims 12 to 16 is sintered. The resulting sintered body. 18. The sintered body according to claim 17 is used as one electrode, and is composed of a dielectric formed on the surface of the sintered body and the other electrode provided on the dielectric. Capacitors. 19. The capacitor according to claim 18, wherein the main component of the dielectric is niobium oxide.