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Tungsten powder, positive electrode body for capacitors, and electrolytic capacitor

An anode body and capacitor technology, applied in electrolytic capacitors, capacitors, circuits, etc., can solve the problems of insufficient leakage current, large leakage current, and no use of tungsten, and achieve good LC characteristics.

Inactive Publication Date: 2013-08-28
SHOWA DENKO KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Using tungsten as the valve metal, an electrolytic capacitor using a sintered body of tungsten powder as an anode body, although compared with an electrolytic capacitor obtained at the same chemical conversion voltage using an anode body of the same volume and using tantalum powder of the same particle size, A large capacity can be obtained, but the leakage current (LC) is large, and it cannot be used as an electrolytic capacitor for practical use
In order to improve this point, capacitors using alloys of tungsten and other metals have been studied, but the leakage current has been somewhat improved but not sufficient (Japanese Patent Laid-Open No. 2004-349658 (US6,876,083B2); Patent Document 1)
[0005] In Patent Document 2 (Japanese Unexamined Patent Publication No. 2003-272959), it is disclosed to use a compound selected from WO 3 , W 2 N, WN 2 A capacitor with electrodes of tungsten foil in the dielectric layer, but not a technical solution for the above leakage current
[0006] In addition, Patent Document 3 (International Publication No. 2004 / 055843 pamphlet (US7,154,743B2)) discloses an electrolytic capacitor using an anode selected from tantalum, niobium, titanium, and tungsten, but tungsten is not used in the specification. Records of specific examples

Method used

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  • Tungsten powder, positive electrode body for capacitors, and electrolytic capacitor

Examples

Experimental program
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Embodiment 1

[0070] Reduce tungstic acid at 980°C in a hydrogen flow to obtain an average particle size of 0.5 μm and a specific surface area of ​​0.3 m 2 / g primary powder of tungsten. Mix 4.8% by mass of commercially available silicon powder (average particle size: 1 μm) prepared separately with this powder, put it into a container made of tungsten, and place it in a vacuum high-temperature furnace with a molybdenum electrode at 3×10 -4 It was left to stand at 1320° C. for 20 minutes under Pa, then cooled until it became room temperature, and returned to normal pressure. Thereafter, it was crushed with a hammer mill, and coarse particles were removed through a sieve with a mesh size of 320 μm to obtain tungsten granulated powder. The obtained granulated powder has an average particle size of 120 μm and a specific surface area of ​​0.2 m 2 / g.

[0071] Elemental analysis of the obtained granulated powder revealed that silicon was 4.8% by mass, oxygen was 0.95% by mass, and other impuri...

Embodiment 2～5 and comparative example 1～2

[0074] In Example 1, except having changed the compounding quantity of silicon, it carried out similarly to Example 1, and obtained the tungsten granulated powder. The average particle diameter and specific surface area of ​​each example are the same as Example 1. The granulated powder obtained in each example had the contents of silicon and oxygen as shown in Table 1, and the other impurity elements were all 350 mass ppm or less.

Embodiment 6

[0076] Commercially available tungsten trioxide powder, pulverized pieces (tungsten silicide balls with a diameter of 1 mm) and water, which are 25 times the mass of the tungsten trioxide powder, are put into the Mitsui Mining Co. (Attritor), crushed at 700°C for 5 hours under hydrogen flow.

[0077] After removing the crushed pieces, the water was evaporated to obtain an average particle size of 0.3 μm and a specific surface area of ​​2.3 m 2 / g primary powder of tungsten. Next, add 3.7% by mass of commercially available silicon powder (average particle size is 1 μm) and mix well, put it into a high-temperature furnace under reduced pressure, and heat it at 7×10 -4 Under Pa, it was left at 1360° C. for 20 minutes. In the middle of the temperature drop to 1000° C., nitrogen gas was added to the furnace so that the temperature was 10 KPa, and it was maintained for 10 minutes. Finally, at room temperature and normal pressure, a mixed gas of 5% by volume of oxygen and 95% by v...

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Abstract

The present invention relates to: a tungsten powder which has tungsten silicide (such as W5Si3) on the surfaces of particles and has a silicon content of 0.05-7% by mass; a positive electrode body for capacitors; an electrolytic capacitor; a method for producing a tungsten powder; and a method for producing a positive electrode body for capacitors. The tungsten powder has an average primary particle diameter of 0.1-1 [mu]m, and tungsten silicide is localized within 50 nm from the surface of each particle. The tungsten powder contains at least one of tungsten nitride, tungsten carbide and tungsten boride in a part of the surface of each particle. It is preferable for the tungsten powder that the content of phosphorus element is 1-500 ppm by mass, the oxygen content is 0.05-8% by mass, and the content of elements other than tungsten, silicon, nitrogen, carbon, boron, oxygen and phosphorus is 0.1% by mass or less. It is also preferable that the tungsten granulated powder has an average particle diameter of 50-200 [mu]m and a specific surface area of 0.2-20 m2 / g. According to the present invention, a tungsten capacitor which has good leakage current (LC) performance can be provided.

Description

technical field [0001] The present invention relates to tungsten powder, an anode body of a capacitor using the tungsten powder, and an electrolytic capacitor using the anode body. Background technique [0002] Along with the miniaturization, speed increase, and weight reduction of electronic equipment such as mobile phones and personal computers, capacitors (condensers) used in these electronic equipment are also required to be smaller, lighter, larger in capacity, and lower in ESR. (equivalent series resistance). [0003] As such a capacitor, the following electrolytic capacitor has been proposed: the anode body of the capacitor composed of a sintered body of valve action metal powder such as tantalum which can be anodized is anodized, and the surface of which is formed by these metal oxides. formed dielectric layer. [0004] Using tungsten as the valve metal, an electrolytic capacitor using a sintered body of tungsten powder as an anode body, although compared with an e...

Claims

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Application Information

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IPC IPC(8): B22F1/00B22F1/02B22F3/10B22F5/00C22C27/04H01G9/00H01G9/052B22F1/12B22F1/148B22F1/16
CPCB22F3/10B22F2201/20C22C1/045C22C27/04H01G9/0525H01G9/042B22F1/148B22F1/16B22F1/12B22F3/12H01G9/00
Inventor 内藤一美
Owner SHOWA DENKO KK
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