JP2003272958A - Solid electrolytic capacitor electrode member and solid electrolytic capacitor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor electrode member which is fabricated by the use of inexpensive material at low sintering temperatures and capable of making a solid electrolytic capacitor very large in capacitance and the solid electrolytic capacitor using the same. <P>SOLUTION: The electrode member is composed of an anode 1 formed of a low-melting valve action metal foil, and a sheet electrode layer 2 which is formed of the powder of valve action metal or its alloy having a higher melting point than the anode 1 and provided on the anode 1. Therefore, the enough adhesion of the electrode layer 2 to the anode 1 can be ensured even if a sintering process is carried out at temperatures lower than usual, and the solid electrolytic capacitor having a small size, a large capacity, a low ESR and a low leakage current can be realized at low cost. <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 solid electrolytic capacitor electrode member used in various electronic devices and a solid electrolytic capacitor using the same.

[0002]

2. Description of the Related Art Generally, it is strongly desired to reduce the size and capacity of electrolytic capacitors used on the secondary side of a power supply circuit or around the CPU of a personal computer, and to reduce the ESR (equivalent series resistance) corresponding to high frequencies. Is required.

FIG. 2 is a perspective view showing a conventional electrode member for a solid electrolytic capacitor of this type. In FIG. 2, 5 is an anode lead wire, and 6 is tantalum, niobium, etc. with the anode lead wire 5 buried therein. Is a sintered body obtained by press-forming and sintering the valve action metal powder of (1) into a desired shape. This sintered body 6 is subjected to chemical conversion treatment after the above-mentioned sintering to form a dielectric oxide film layer on the surface, Further, a solid electrolyte layer and a cathode layer (neither of which is shown) are sequentially formed on the dielectric oxide film layer in a laminated state to form an electrode member for a solid electrolytic capacitor.

In the conventional solid electrolytic capacitor electrode member thus constructed, the external lead terminal (not shown) is connected to the anode lead wire 5 and the external cathode terminal (not shown) is also connected to the cathode layer. The solid electrolytic capacitor is obtained by molding (not shown) so as to cover the whole with an insulating epoxy resin or the like.

Further, in the recent technology, for the purpose of lowering ESR, a solid electrolyte using a functional polymer having an order of magnitude higher conductivity than that of conventional manganese dioxide is used as a material for forming the solid electrolyte layer. Capacitors have been developed and are expanding their market. Further, as an effort to reduce the size and capacity of a solid electrolytic capacitor using such a functional polymer as a solid electrolyte, in the technique described in JP-A-2000-306782, As shown in FIG. 3, an anode body 7 made of a valve action metal foil was used, and a sheet-shaped electrode layer 8 made of a valve action metal powder having a high CV value was provided on the surface of the anode body 7 on the surface of a sintered body. Dielectric oxide layer (not shown), solid electrolyte layer 9,
A technique for forming a solid electrolytic capacitor having a small size and a large capacity by sequentially forming the cathode layers 10 has been disclosed.

[0006]

However, in the above-mentioned conventional solid electrolytic capacitor, the unit price of tantalum, which is currently mainly used as a valve metal, is very expensive, and the melting point is extremely high at 2990 ° C. The sintering temperature is inevitably high, and therefore the energy cost to use is also high. Further, because the metal foil is generally inferior in sinterability to the metal powder due to the shape factor, the solid having the structure shown in FIG. In the electrolytic capacitor, there is a problem in the adhesion between the valve metal foil and the valve metal powder after sintering, and there is a problem that the sintering temperature cannot be lowered.

Recently, in addition to the above tantalum powder,
Niobium powder is being actively studied because of its rich reserves and low cost, but niobium powder has a lower specific surface area than tantalum powder, so it has a low capacitance and a large leakage current, so it is put to practical use. It was difficult to do.

The present invention solves such conventional problems,
Can be manufactured with low cost materials at low sintering temperatures,
Moreover, it is an object of the present invention to provide a solid electrolytic capacitor electrode member capable of realizing a large capacity and a solid electrolytic capacitor using the same.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention provides a valve action metal foil having a low melting point and a valve action metal having a melting point higher than that of the valve action metal foil or It is a structure of a solid electrolytic capacitor electrode member consisting of an electrode layer formed on the valve action metal foil by using the powder of the alloy, whereby the valve action metal foil and the valve action metal powder are Adhesion between the valve action metal foil and the electrode layer can be ensured even if it is sintered at a low temperature, and there is an effect that the cost can be reduced without deteriorating the leakage current.

The invention according to claim 2 of the present invention is
This is a structure in which niobium foil is used as the low melting point valve action metal foil and tantalum is used as the valve action metal.

The invention according to claim 3 of the present invention is
In this structure, a niobium foil is used as the low melting point valve action metal foil and an alloy containing niobium is used as the valve action metal alloy.

The invention according to claim 4 of the present invention is
In this structure, a niobium foil is used as the low melting point valve action metal foil and an alloy of tantalum and niobium is used as the valve action metal alloy.

The invention according to claim 5 of the present invention is
The solid electrolytic capacitor has a structure in which a dielectric oxide film layer, a solid electrolyte layer, and a cathode layer are sequentially laminated on the electrode layer of the electrode member for a solid electrolytic capacitor. The solid electrolytic capacitor can be provided at low cost.

The invention according to claim 6 of the present invention is
The solid electrolytic capacitor has a structure in which two or more solid electrolytic capacitors are laminated. This has an effect that a solid electrolytic capacitor having a low ESR and a large capacity can be provided at a low cost.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The invention described in claims 1 to 6 of the present invention will be described below with reference to the embodiments.

FIG. 1 is a perspective view showing a partial cross-section of the structure of an electrode member for a solid electrolytic capacitor according to an embodiment of the present invention. In FIG. 1, 1 is a valve metal foil having a purity of 99% or more. By applying powder of valve action metal or alloy having a higher melting point than the valve action metal foil forming the anode body 1 to the surface of the anode body 1 in the form of a paste and then sintering in a vacuum atmosphere. A sintered body provided with a sheet-shaped electrode layer 2 is formed, and this is anodized in a phosphoric acid solution at about 10 V to form a dielectric oxide film layer (not shown) on the surface, followed by pyrrole. The solid electrolyte layer 3 is formed by chemical oxidative polymerization, and carbon and silver paste are applied to sequentially form the cathode layer 4 in a laminated state to form an electrode member for a solid electrolytic capacitor.

Further, in order to improve the performance of the electrode member for a solid electrolytic capacitor of the present embodiment configured as described above and to make it small in size and large in capacity, in order to make full use of the valve action metal powder having a high CV value, It is necessary to suppress the thickness of the electrode member to facilitate the extraction of the capacitance after the solid electrolyte layer 3 is formed,
Therefore, by using a valve metal foil as the anode body 1, a thin electrode member having a thickness of about 300 μm is formed to form a single-layer capacitor element, and by stacking a plurality of such capacitor elements, a small size, large capacity, and low ESR are obtained. In addition, it is possible to obtain a solid electrolytic capacitor having excellent performance with low leakage current.

The anode body 1 made of the above valve metal foil is used.
Regarding the relationship between the sheet-like electrode layer 2 and the sheet-like electrode layer 2, since the metal foil is generally inferior in sinterability to the metal powder due to its shape factor, a metal foil having a low melting point is used to enhance the sinterability, and thereby Even if the foil and the metal powder applied in the form of a paste are sintered at a low temperature, the sheet-shaped electrode layer 2 can be formed, and the solid-solved alloy is better than one refractory metal. Since the melting point is lowered, the sintering temperature can be further lowered in the sintering of the alloy powder of the valve action metals and the foil.

Further, by using a niobium foil having a low melting point of 2470 ° C. as the valve action metal foil constituting the anode body 1 and using tantalum as the valve action metal powder constituting the sheet-like electrode layer 2, Even if it is sintered at a low temperature as compared with tantalum, it is possible to sufficiently secure the adhesion between the two and to reduce the cost without deteriorating the leakage current.

Further, a niobium foil having a low melting point of 2470 ° C. is used as the valve metal foil constituting the anode body 1, and an alloy containing niobium or an alloy of niobium and tantalum is used as the valve metal powder constituting the sheet-shaped electrode layer 2. By adopting the configuration using, it is possible to secure sufficient adhesion between the two even when sintered at a lower temperature than tantalum, and it is possible to further reduce the cost without deteriorating the leakage current. Since this alloy of niobium and tantalum has a higher capacity than tantalum and is an alloy with low cost niobium, it is necessary to reduce the cost compared to the case of using only tantalum. Is something that can be done.

The solid electrolytic capacitor of the present embodiment having the above-described structure is used by changing the kinds of the valve action metal foil which constitutes the anode body 1 and the valve action metal powder which constitutes the sheet-like electrode layer 2. 5 kinds of 1 to 5 are produced, and their capacitance, 100 kHz ESR (equivalent series resistance) and LC
The results of measuring the (leakage current) characteristics and the results of calculating the cost index thereof with the conventional tantalum as 100 are shown in Table 1 in comparison with the three types of conventional examples.

[0022]

[Table 1]

Conventional Examples 1 and 2 and Example 1 of this (Table 1)
As is clear from the comparison between Nos. 2 and 3 and the comparison between Conventional Example 3 and Example 5, the combination of the low melting point niobium foil and the tantalum powder or the alloy powder of niobium and tantalum is compared to the conventional example. It is possible to obtain a solid electrolytic capacitor having a large capacity and a low leakage current at a low cost.

[0024]

As described above, the solid electrolytic capacitor according to the present invention uses the valve-action metal foil having a low melting point and the valve-action metal or its alloy powder having a melting point higher than that of the valve-action metal foil. By adopting a configuration consisting of the electrode layer formed on the foil, it becomes possible to sufficiently secure the adhesion between the valve action metal foil and the electrode layer even if the sintering is performed at a lower temperature than the conventional one, By stacking a plurality of the solid electrolytic capacitor melting electrode members, a solid electrolytic capacitor having a small size, a large capacity, a low ESR, and a low leakage current can be realized at a low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing a partial cross-section of the structure of an electrode member for a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a conventional electrode member for a solid electrolytic capacitor.

FIG. 3 is a perspective view showing the structure of a conventional electrode member for a solid electrolytic capacitor in a partial cross section.

[Explanation of symbols]

1 Anode body 2 Sheet-shaped electrode layer 3 Solid electrolyte layer 4 cathode layer

Continued front page    (72) Inventor Hideki Masumi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd.

Claims (6)

[Claims] 1. A solid electrolysis comprising a valve-action metal foil having a low melting point and an electrode layer formed on the valve-action metal foil using powder of a valve-action metal or an alloy thereof having a melting point higher than that of the valve-action metal foil. Electrode member for capacitors. 2. The electrode member for a solid electrolytic capacitor according to claim 1, wherein niobium foil is used as the low melting point valve action metal foil and tantalum is used as the valve action metal. 3. The electrode member for a solid electrolytic capacitor according to claim 1, wherein a niobium foil is used as the valve metal foil having a low melting point, and an alloy containing niobium is used as an alloy of the valve metal. 4. The electrode member for a solid electrolytic capacitor according to claim 1, wherein a niobium foil is used as the valve metal foil having a low melting point, and an alloy of tantalum and niobium is used as an alloy of the valve metal. 5. A solid oxide capacitor layer, a dielectric oxide film layer, a solid electrolyte layer, and a cathode layer are sequentially laminated on an electrode layer of a solid electrolytic capacitor electrode member, and the solid electrolytic capacitor electrode layer is a valve metal foil having a low melting point. And a solid electrolytic capacitor comprising an electrode layer formed on the valve action metal foil by using a powder of the valve action metal or its alloy having a melting point higher than that of the valve action metal foil. 6. A solid electrolytic capacitor in which two or more solid electrolytic capacitors according to claim 5 are laminated.