JP2005079520A - Coin-type solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor having superior damp-proof and leak current characteristics, by solving the problems of oxidation deterioration and deterioration in characteristic due to stress during assembly as a solid electrolytic capacitor, using conductive macromolecules for a solid electrolyte. <P>SOLUTION: The anode part of a capacitor element 1 is connected to a dish-shaped 1st metal case 8 and the anode part is connected to a dish-shaped 2nd metal case 9, which is connected covering closing the 1st metal case 8; and the 1st and 2nd metal cases 8 and 9 are connected together to maintain superior airtightness with a high sealing force, so the possibility that external oxygen reaches the capacitor element 1 put therein to cause oxidation deterioration becomes extremely low and stress is no longer applied during assembly, to provide the solid electrolytic capacitor which has superior damp-proof and leak current characteristics and is made small-sized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coin-type solid electrolytic capacitor using, as a solid electrolyte, a conductive polymer excellent in low profile, moisture resistance, and leakage current characteristics among capacitors used in various electronic devices.

  Along with the higher frequency of electronic devices, capacitors that are one of the electronic components are also required to have better ESR (equivalent series resistance) characteristics in the higher frequency range than before. Various solid electrolytic capacitors using a highly conductive polymer as a solid electrolyte have been studied.

  FIG. 7 is a sectional view showing the structure of this type of conventional solid electrolytic capacitor, and FIG. 8 is a partially cutaway perspective view showing a capacitor element used in this solid electrolytic capacitor. Reference numeral 24 denotes a capacitor element. The capacitor element 24 roughens the surface of an anode body 25 made of an aluminum foil, which is a valve metal, and is subjected to a chemical conversion treatment to form a conversion film (not shown) of aluminum oxide, which is a dielectric. 2), a polyimide adhesive tape 26 for forming an insulating portion is attached to a predetermined position of the anode body 25 to separate the anode portion 27 and the cathode portion 28, and the surface of the cathode portion 28 is electrically conductive. A solid electrolyte layer 29 made of a polymer and a cathode layer 30 made of carbon and silver paste are sequentially laminated and formed.

  Reference numeral 31 denotes an anode lead frame obtained by integrally bonding the anode portions 27 of the capacitor elements 24 in a state where a plurality of the capacitor elements 24 having the above-described configuration are stacked, and 32 denotes the cathode layer 30 of each capacitor element 24 in the same manner. An integrally connected cathode lead frame 33 is an insulating exterior resin that integrally covers the plurality of capacitor elements 24 in a state where parts of the anode lead frame 31 and the cathode lead frame 32 are exposed on the outer surface. In general, an epoxy resin is often used for the exterior resin 33.

  In the conventional solid electrolytic capacitor configured as described above, the external lead 31a is formed by bending the anode lead frame 31 and the cathode lead frame 32 exposed from the exterior resin 33 from the side surface to the bottom surface along the outer surface of the exterior resin 33. And 32a were respectively formed, thereby forming a surface mount type solid electrolytic capacitor.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 9-320895

  However, in the above-described conventional solid electrolytic capacitor, various conductive polymers for forming the solid electrolyte layer 29 have been developed, and although application development to the solid electrolytic capacitor has been advanced at a rapid pace, Since all conductive polymers are organic, they cause oxidative degradation in an oxygen atmosphere, which leads to reduced conductivity and reduced adhesion and stability with the dielectric oxide film layer. In particular, it has been found that the deterioration of capacitor characteristics (especially capacity reduction and ESR increase) is caused in a high humidity atmosphere.

  In order to solve these problems, in the conventional solid electrolytic capacitor of this type, the capacitor element 24 and the cathode lead frame 32 are particularly roughened by roughening the interface of the cathode lead frame 32 connected to the capacitor element 24. The adhesion between the exterior resin 33 and the cathode lead frame 32 for molding a part of the exterior resin 33 is improved, and the thickness of the exterior resin 33 is increased to increase the distance between the cathode lead frame 32 and the capacitor element 24, thereby reducing the cathode lead. Attempts have been made to prevent oxidative degradation in an oxygen atmosphere by increasing the contact distance between the frame 32 and the exterior resin 33 as much as possible.

  However, if the method of increasing the contact distance between the cathode lead frame 32 and the exterior resin 33 by increasing the thickness of the exterior resin 33 and increasing the distance between the cathode lead frame 32 and the capacitor element 24 as described above, the outer shape is obtained. As a result, the size is increased, and as a result, there is a problem that miniaturization becomes extremely difficult.

  The present invention solves such a conventional problem, prevents oxidative deterioration due to external oxygen reaching the capacitor element, does not deteriorate leakage current characteristics due to stress during assembly, and is reduced in thickness. An object of the present invention is to provide a coin-type solid electrolytic capacitor that can be realized.

  In order to solve the above-mentioned problems, an invention according to claim 1 of the present invention is a capacitor element in which a conductive polymer is used as a solid electrolyte and an anode extraction part and a cathode extraction part are formed, and an anode of this capacitor element. A dish-shaped first metal case to which the take-out part is connected, a dish-like second metal case to which the cathode take-out part is connected and closed so as to close the first metal case, and the first metal case; The coin-shaped solid electrolytic capacitor is formed of a sealing material that is disposed at the periphery between the second metal cases and performs insulation and sealing, and thereby connects the dish-shaped first and second metal cases. As a result, a high sealing force can be exhibited and excellent airtightness can be maintained, so the probability that external oxygen will reach the capacitor element accommodated therein and cause oxidative degradation is extremely low. Excellent moisture resistance, and because the capacitor element is sealed with two dish-shaped metal cases, no physical stress is applied to the capacitor element, so that the leakage current characteristics are stabilized. In addition, the solid electrolytic capacitor having a reduced thickness can be provided stably.

  According to a second aspect of the present invention, there is provided a capacitor element comprising an anode body comprising a valve-acting metal foil having a roughened surface and a dielectric oxide film layer provided with an insulating portion. The cathode part is separated, and a solid electrolyte layer made of a conductive polymer and a cathode layer are sequentially laminated on the cathode part.

  According to a third aspect of the present invention, the capacitor element is formed by laminating an anode foil formed by etching to form a dielectric oxide film layer and an etched cathode foil with a separator interposed therebetween, and the anode In this configuration, a solid electrolyte layer made of a conductive polymer is formed between the foil and the cathode foil.

  The invention according to claim 4 of the present invention is such that the conductive polymer forming the solid electrolyte layer is one or more of polypyrrole, polyaniline, and polyethylenedioxythiophene, and / or derivatives thereof, and / or their It consists of the compound of.

  According to a fifth aspect of the present invention, the capacitor element is fixed to the first metal case through an insulating member.

  According to the sixth aspect of the present invention, the capacitor element is fixed to the second metal case through a silver paste, a carbon paste, or a conductive adhesive.

  The invention according to claim 7 of the present invention has a configuration in which a plurality of capacitor elements are laminated, and has an effect of easily increasing the capacity.

  In the invention according to claim 8 of the present invention, one end of the external terminal is joined to the first metal case and the second metal case, respectively, and the other end of the pair of external terminals is disposed on the same surface. It has a configuration in which the mounting surface is used, and has an effect of being able to easily cope with the surface mounting type.

  As described above, in the coin-type solid electrolytic capacitor according to the present invention, the anode extraction portion of the capacitor element using the conductive polymer as the solid electrolyte is connected to the dish-shaped first metal case, and the cathode extraction portion is similarly formed as the dish-shaped solid electrolytic capacitor. By connecting to the second metal case and connecting the second metal case so as to close the first metal case, the first metal case and the second metal case are combined to provide a high sealing force. Therefore, since the probability that external oxygen reaches the capacitor element accommodated therein and causes oxidative degradation is extremely low, it has excellent moisture resistance, and two Due to the configuration in which the capacitor element is sealed with a dish-shaped metal case, no physical stress is applied to the capacitor element, so that the leakage current characteristic is stabilized, and In which it exhibits the special effect of a solid electrolytic capacitor which attained types of can be provided stably.

(Embodiment 1)
Hereinafter, the first and second aspects of the present invention will be described with reference to the first embodiment.

  FIG. 1 is a cross-sectional view showing a configuration of a coin-shaped solid electrolytic capacitor according to Embodiment 1 of the present invention, and FIG. 2 is a partially cutaway perspective view showing a capacitor element used in the coin-shaped solid electrolytic capacitor. 1 and 2, reference numeral 1 denotes a capacitor element. The capacitor element 1 roughens the surface of an anode body 2 made of an aluminum foil, which is a valve action metal, and is subjected to chemical conversion treatment to oxidize as a dielectric. After forming a chemical conversion film (not shown) of aluminum, a polyimide adhesive tape 3 for forming an insulating portion is attached to a predetermined position of the anode body 2 to separate the anode portion 4 and the cathode portion 5. A structure in which a solid electrolyte layer 6 made of polypyrrole as a conductive polymer and a cathode layer 7 made of carbon and silver paste are sequentially laminated on the surface of the portion 5 A.

  8 and 9 are a first metal case and a second metal case formed in a circular dish shape, and 10 is for insulating or fixing the capacitor element 1 on the inner surface of the first metal case 8. An insulating sheet, 11 is a lead wire for electrically connecting the anode part 4 of the capacitor element 1 to the first metal case 8, and 12 is a cathode layer 7 for fixing the capacitor element 1 to the inner surface of the second metal case 9. The first metal case 8 serves as an anode and the second metal case 9 serves as a cathode.

  13 is a sealing member that is disposed on the periphery between the first metal case 8 and the second metal case 9 and performs insulation and sealing by curling the periphery of the first and second metal cases 8 and 9 together. In this embodiment, the sealing material 13 is made of butyl rubber.

  The coin-type solid electrolytic capacitor according to the present embodiment configured as described above exhibits a high sealing force by joining the dish-shaped first and second metal cases 8 and 9, and maintains excellent airtightness. Therefore, the probability that external oxygen reaches the capacitor element 1 accommodated in the capacitor element 1 to cause oxidative degradation is extremely low, and thus a solid electrolytic capacitor having excellent moisture resistance and a reduced thickness can be obtained. In addition, since the capacitor element 1 is sealed with the dish-shaped first / second metal cases 8 and 9, the capacitor element 1 is mechanically sealed at the time of sealing. Therefore, it is possible to realize a solid electrolytic capacitor with a low leakage current because it is not subjected to excessive stress. Such moisture resistance characteristics and leakage current characteristics are compared with the conventional product as a comparative example. It is shown in (Table 1).

  As apparent from Table 1, the value of the leakage current after aging of the coin-type solid electrolytic capacitor according to the present embodiment is lower than that of the conventional product. This is because, in the conventional product, mechanical stress is applied when the capacitor element after polymerization is covered with the exterior resin, whereas in the solid electrolytic capacitor according to the present embodiment, mechanical stress is applied when the capacitor element is sealed. It is because it does not take. In the test at 85 ° C. and 85% RH, the solid electrolytic capacitor according to the present embodiment has a smaller rate of change with respect to the initial capacitance than the conventional product. This is because in the conventional product, moisture enters the capacitor element through the exterior resin in an atmosphere of 85 ° C. and 85%. In contrast, in the solid electrolytic capacitor according to the present embodiment, the sealing is performed with the sealing material 13 using butyl rubber, and thus surface permeation is suppressed by the expansion of the rubber at a high temperature.

  In the present embodiment, the configuration using the lead wire 11 as an example of means for electrically connecting the anode portion 4 of the capacitor element 1 to the first metal case 8 has been described. However, the present invention is not limited thereto. The configuration is not limited, and the anode portion 4 may be directly connected to the first metal case 8.

  Moreover, although the example which used polypyrrole as the solid electrolyte layer 6 which consists of a conductive polymer which comprises the capacitor | condenser element 1 was demonstrated, polyaniline and polyethylene dioxythiophene may be used individually or in combination in addition to this. It ’s good.

  Moreover, although the example which used aluminum foil as the anode body 2 which consists of the valve action metal which comprises the capacitor | condenser element 1 was demonstrated, the same effect is obtained even if it uses tantalum foil, niobium foil, etc. besides this. is there.

(Embodiment 2)
Hereinafter, the invention described in claim 3 of the present invention will be described with reference to the second embodiment.

  The present embodiment is different from the first embodiment in the configuration of the capacitor element of the coin-type solid electrolytic capacitor, and the other configurations are the same as those in the first embodiment. The detailed description will be omitted, and only different parts will be described below with reference to the drawings.

  FIG. 3 is a partially cutaway perspective view showing a configuration of a coin-shaped solid electrolytic capacitor according to Embodiment 2 of the present invention, and FIG. 4 is a cross-sectional view showing a capacitor element used in the coin-shaped solid electrolytic capacitor. 3 and 4, reference numeral 14 denotes a capacitor element. The capacitor element 14 is formed by etching an aluminum foil to form an anode foil 15 on which a dielectric oxide film layer (not shown) is formed, and also etching the aluminum foil. A cathode foil 16 is laminated with a separator 17 made of a polyethylene terephthalate nonwoven fabric interposed therebetween, and a solid electrolyte layer 18 made of polyethylene dioxythiophene, which is a conductive polymer, between the anode foil 15 and the cathode foil 16. Is formed.

  Reference numerals 8 and 9 denote a first metal case and a second metal case. The capacitor element 14 has the anode foil 15 in the first metal case 8 and the cathode foil 16 in the second metal by means not shown, as in the first embodiment. The first metal case 8 is electrically connected to the metal case 9 and is assembled by disposing the sealing material 13 on the periphery between the first metal case 8 and the second metal case 9 and curling. In addition, the second metal case 9 is configured to be a cathode.

  The coin-type solid electrolytic capacitor according to the present embodiment configured as described above exhibits excellent airtightness, excellent moisture resistance, and thickness reduction, similarly to the coin-type solid electrolytic capacitor according to the first embodiment. It is possible to provide the intended solid electrolytic capacitor. Further, since the capacitor element 14 is sealed with the dish-shaped first / second metal cases 8 and 9, no mechanical stress is applied to the capacitor element 14 at the time of sealing. A low solid electrolytic capacitor can be realized.

  In the present embodiment, the example in which polyethylene dioxythiophene is used as the solid electrolyte layer 18 made of a conductive polymer constituting the capacitor element 14 has been described, but the present invention is not limited to this. Even if polyaniline and polypyrrole are used alone or in combination, the same effects can be obtained.

  Moreover, although the example which used the nonwoven fabric of the polyethylene terephthalate as the separator 17 which comprises the capacitor | condenser element 14 was demonstrated, it is the same even if it uses the separator which consists of resin fibers, such as a polypropylene and polyethylene, or the nonwoven fabric of resin other than this Thus, the following effects can be obtained.

(Embodiment 3)
The third aspect of the present invention will be described below with reference to the seventh embodiment.

  This embodiment has a configuration in which a plurality of capacitor elements of the coin-type solid electrolytic capacitor according to the first embodiment are stacked, and other configurations are the same as those in the first embodiment, and therefore the same parts are the same. Detailed description thereof will be omitted, and only different parts will be described below with reference to the drawings.

  FIG. 5 is a cross-sectional view showing the configuration of a coin-type solid electrolytic capacitor according to Embodiment 3 of the present invention. In FIG. 5, reference numeral 1 denotes the capacitor element described with reference to FIG. In the embodiment, two capacitor elements 1 are stacked and further integrated to form a cathode layer 7 made of silver paste.

  With such a configuration, it is possible to easily increase the capacity and reduce the ESR.

  Although the present embodiment has been described using an example in which two capacitor elements 1 are stacked, the present invention is not limited to this, and the effect increases as the number of stacked layers increases. .

(Embodiment 4)
Hereinafter, the fourth aspect of the present invention will be described with reference to the fourth embodiment.

  In this embodiment, the coin-type solid electrolytic capacitor according to the first embodiment is joined to an external terminal for taking out an electrode. Since the other configuration is the same as that of the first embodiment, the same portion is used. Are given the same reference numerals and detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  6 (a) and 6 (b) are front views showing the configuration of a coin-type solid electrolytic capacitor according to Embodiment 4 of the present invention. In FIGS. 6 (a) and 6 (b), reference numerals 19 and 21 denote the above-described embodiments. External terminals for taking out anode-side electrodes joined to the first metal case 8 of the coin-shaped solid electrolytic capacitor according to the first embodiment, and 20 and 22 are external parts for taking out the cathode-side electrodes joined to the second metal case 9 respectively. The external terminal 19 (21) is configured to be mounted on the mounting surface of the printed circuit board 23 together with the other external terminal 20 (22) by being bent stepwise so that it can be surface mounted. is there.

  6A shows a configuration in which the external terminals 19 and 20 are taken out in opposite directions, and FIG. 6B shows a configuration in which the external terminals 21 and 22 are taken out in the same direction. It is only necessary to respond to the situation.

  The coin-type solid electrolytic capacitor according to the present invention is excellent in moisture resistance and has a feature that it can be thinned. Therefore, the coin-type solid electrolytic capacitor is particularly useful as a solid electrolytic capacitor or the like in a field where low profile and moisture resistance are required.

Sectional drawing which showed the structure of the coin-shaped solid electrolytic capacitor by Embodiment 1 of this invention Partially cutaway perspective view showing a capacitor element used in the coin-type solid electrolytic capacitor Partially cutaway perspective view showing the configuration of a coin-shaped solid electrolytic capacitor according to Embodiment 2 of the present invention Sectional view showing the capacitor element used in the coin-type solid electrolytic capacitor Sectional drawing which showed the structure of the coin-shaped solid electrolytic capacitor by Embodiment 3 of this invention (A), (b) The front view which showed the structure of the coin type solid electrolytic capacitor by Embodiment 4 of this invention Sectional view showing the structure of a conventional solid electrolytic capacitor Partially cutaway perspective view showing a capacitor element used in the solid electrolytic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,14 Capacitor element 2 Anode body 3 Polyimide adhesive tape 4 Anode part 5 Cathode part 6,18 Solid electrolyte layer 7 Cathode layer 8 1st metal case 9 2nd metal case 10 Insulation sheet 11 Lead wire 12 Conductive adhesive 13 Sealing Material 15 Anode foil 16 Cathode foil 17 Separator 19, 20, 21, 22 External terminal 23 Printed circuit board

Claims (8)

A capacitor element using a conductive polymer as a solid electrolyte and having an anode extraction part and a cathode extraction part, a dish-shaped first metal case to which the anode extraction part of the capacitor element is connected, and a cathode extraction part And a dish-shaped second metal case joined so as to close the first metal case, and a sealing member disposed on the periphery between the first metal case and the second metal case for insulation and sealing. Coin-shaped solid electrolytic capacitor made of materials. Capacitor elements are provided with an insulating part on an anode body made of a valve-acting metal foil having a roughened surface and a dielectric oxide film layer, and are separated into an anode part and a cathode part. 2. The coin-type solid electrolytic capacitor according to claim 1, wherein a solid electrolyte layer made of a polymer and a cathode layer are sequentially laminated. A capacitor element is laminated by etching an anode foil having a dielectric oxide film layer formed thereon and an etched cathode foil with a separator interposed therebetween, and a conductive polymer between the anode foil and the cathode foil. The coin-shaped solid electrolytic capacitor according to claim 1, wherein a solid electrolyte layer is formed. 2. The coin according to claim 1, wherein the conductive polymer forming the solid electrolyte layer is composed of one or more conductive polymers of polypyrrole, polyaniline, and polyethylenedioxythiophene, dielectrics thereof, and / or compounds thereof. Type solid electrolytic capacitor. The coin-shaped solid electrolytic capacitor according to claim 1, wherein the capacitor element is fixed to the first metal case via an insulating member. The coin-shaped solid electrolytic capacitor according to claim 1, wherein the capacitor element is fixed to the second metal case through any one of silver paste, carbon paste, and conductive adhesive. The coin-shaped solid electrolytic capacitor according to claim 1, wherein a plurality of capacitor elements are laminated. The coin shape according to claim 1, wherein one end of the external terminal is joined to each of the first metal case and the second metal case, and the other end of the pair of external terminals is disposed on the same surface to be a mounting surface on the substrate. Solid electrolytic capacitor.

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