JP2004006573A - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small size solid electrolytic capacitor having large capacitance which realizes a low ESR and low ESL. <P>SOLUTION: In a rectangular solid electrolytic capacitor, a capacitor element formed by isolating a rectangular anode body consisting of a metal for valve operation into an anode portion and a cathode portion in the shorter-side direction is covered with externally mounted resin. Since a pair of external electrodes 2 are provided opposing to the side of longer-side, a product length making contribution to an ESL can be formed short by making shorter the distance between external electrodes 2 than the longer-side and the ESL can be remarkably lowered by eliminating elongation of electrode through introduction of a comb terminal. Accordingly, the solid electrolytic capacitor realizing reduction in size, a low ESL and low ESR can be provided stably. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid electrolytic capacitor used for various electronic devices and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, there has been a strong demand for electrolytic capacitors used around CPUs of personal computers to have a small size and a large capacity. In addition to a reduction in ESR (equivalent series resistance) corresponding to a high frequency, furthermore, a transient response is required. There is a demand for excellent low ESL, and various solid electrolytic capacitors are being studied to meet such demands.
[0003]
FIG. 13 is a perspective view showing the configuration of a conventional solid electrolytic capacitor of this type, FIG. 14 is a sectional view of the same, FIG. 15 is a perspective view showing the same capacitor element, and in FIGS. A capacitor 31 is a capacitor element. The capacitor element 31 is a rectangular (long side L × short side W) aluminum foil whose surface area is enlarged by etching, or a valve action metal powder (tantalum, niobium) having an anode lead wire embedded therein. ) Is formed into a rectangular shape and sintered and used as an anode body. The anode body is separated into an anode section 36 and a cathode section 37 in the long side direction by a resist material 35, and then the cathode section 37 is electrolyzed. A dielectric oxide layer (not shown) is formed on the outer surface by anodic oxidation (chemical formation) in a liquid, and a solid electrolyte layer (not shown) and a cathode layer 38 are sequentially laminated on the dielectric oxide layer. Those constructed by forming.
[0004]
Reference numerals 32 and 33 denote an anode comb terminal and a cathode comb terminal which are formed by laminating a plurality of the capacitor elements 31 constructed as described above and are respectively connected on the short side (W) side. Is an insulative exterior resin integrally covering a plurality of capacitor elements 31 in a state where a part of each is exposed to the outside, so that an anode comb is formed on the short side of a rectangular shape (long side L × short side W). A solid electrolytic capacitor having a terminal 32 and a cathode comb terminal 33, each of which has a small size and a large capacity, and which can be mounted on a surface is configured.
[0005]
FIG. 16 is a characteristic diagram showing the results of measuring the ESL characteristics of various capacitors currently available including such a conventional solid electrolytic capacitor. As is clear from FIG. And the ESL of the type in which the capacitor element made of an anode body using tantalum powder is connected to the comb terminal is the highest when compared with the same product length, followed by the anode body using an aluminum foil It can be seen that the ESL of the type in which the capacitor element is connected to the comb terminal is high, and the ESL of the type in which the capacitor element formed of an anode body using aluminum foil is collected at the end face is high.
[0006]
[Problems to be solved by the invention]
However, in the conventional solid electrolytic capacitors shown in FIGS. 13 to 15, the anode portion 36 and the cathode layer 38 of the rectangular capacitor element 31 made of an anode body using aluminum foil are opposed to the short side (W) side. Since it was developed mainly for miniaturization and large capacity and low ESR by connecting to the anode comb terminal 32 and the cathode comb terminal 33 provided respectively, as is clear from FIG. When the ESL characteristics were evaluated, the performance was not satisfactory.
[0007]
An object of the present invention is to solve such a conventional problem and to provide a solid electrolytic capacitor which is small in size and large in capacity and achieves both low ESR and low ESL, and a method of manufacturing the same.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 of the present invention separates a rectangular anode body made of a valve action metal into an anode section and a cathode section in a short side direction, and forms a dielectric on the surface of the cathode section. A capacitor element in which a body oxide film layer, a solid electrolyte layer, and a cathode layer are sequentially laminated, an insulating sheath resin in which the capacitor elements are singly or two or more laminated, and a length of the sheath resin. The anode portion and the cathode portion are provided so as to face each other, and the anode portion and the cathode portion are each formed of a pair of external electrodes. This makes it possible to increase the distance between the pair of external electrodes contributing to the ESL. Since it is possible to shorten the length and eliminate the electrode routing by the comb terminal, there is an operational effect that the ESL can be greatly reduced.
[0009]
According to a second aspect of the present invention, in the first aspect of the invention, a rectangular anode body made of a valve metal is formed on a valve metal foil or a valve metal foil having a roughened surface. This is a configuration in which a sintered layer made of valve metal powder is formed, and thereby has the same operation and effect as the operation and effect obtained by the first aspect of the present invention.
[0010]
The invention according to claim 3 of the present invention is the invention according to claim 1, wherein the valve action metal is aluminum, tantalum, niobium, or an alloy thereof. This has the effect of being able to realize a small, large-capacity solid electrolytic capacitor.
[0011]
According to a fourth aspect of the present invention, in the first aspect of the present invention, the solid electrolyte layer is made of a conductive polymer. This has the effect that the ESR can be reduced.
[0012]
According to a fifth aspect of the present invention, in the first aspect of the present invention, a part of the anode part of the anode body constituting the capacitor element is cut out, and the cut parts are alternately arranged so as not to overlap. It is a configuration in which a plurality of capacitor elements are stacked upside down, whereby the exterior resin is sufficiently filled in a part of the anode part of the anode body that forms the capacitor element by cutting out the anode part. Therefore, the solid electrolytic capacitor having a high airtightness can be obtained.
[0013]
The invention described in claim 6 of the present invention is the invention according to claim 1, wherein one of the cathode layer and the external electrode of each capacitor element is connected via a silver or copper plate or a rivet. Accordingly, the cathode and the external electrode of the capacitor element are connected at the shortest distance, so that there is an operational effect that the ESL can be greatly reduced.
[0014]
According to a seventh aspect of the present invention, in the first aspect, the external electrode is formed by a plating layer, thereby achieving both low ESR and low ESL. Has the effect of being able to
[0015]
According to an eighth aspect of the present invention, in the first aspect of the present invention, the surfaces which become the mounting surfaces of the pair of external electrodes provided to face each other on the long side are extended in a direction in which they are close to each other. This is a configuration in which the area is enlarged, which has the effect of reducing the ESL by further reducing the distance between the external electrodes.
[0016]
According to a ninth aspect of the present invention, in the first aspect of the present invention, the height from a surface serving as a mounting surface of a pair of external electrodes provided to face the long side is set in the same direction as the exterior resin. The height is smaller than the height of the mounting surface, which can prevent a phenomenon in which another electronic component or the like comes into contact with the external electrode on the surface opposite to the mounting surface to cause a short circuit. Having.
[0017]
According to a tenth aspect of the present invention, in the first aspect of the invention, an insulating material is provided on a pair of external electrodes exposed to face opposite to a surface serving as a mounting surface. This has the same function and effect as the function and effect obtained by the invention according to claim 9.
[0018]
According to an eleventh aspect of the present invention, a rectangular anode body made of a valve metal foil subjected to a surface roughening treatment is separated into an anode part and a cathode part in a short side direction, and a dielectric material is formed on the surface of the cathode part. A capacitor element is manufactured by sequentially forming a body oxide film layer, a solid electrolyte layer, and a cathode layer, and then a plurality of the capacitor elements are laminated and covered with an insulating exterior resin. This is a method for manufacturing a solid electrolytic capacitor in which a pair of external electrodes, to which a negative electrode part and a negative electrode part are respectively connected, are provided so as to face the long side of the exterior resin. This has the effect of stably producing the electrolytic capacitor.
[0019]
According to a twelfth aspect of the present invention, in the invention of the eleventh aspect, after stacking a plurality of capacitor elements, each cathode layer is electrically integrated by connecting a metal rivet to the cathode layer. This method has the same function and effect as the function and effect obtained by the invention according to claim 11.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Hereinafter, the first embodiment of the present invention will be described with reference to the first to fourth, sixth, seventh, eleventh, and twelfth embodiments.
[0021]
1 is a perspective view showing a configuration of a solid electrolytic capacitor according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, FIG. 3 is a perspective view before the same mold, and FIG. It is the perspective view which showed the capacitor element.
[0022]
In FIG. 1, reference numeral 1 denotes a solid electrolytic capacitor, and 2 denotes an external electrode. The external electrode 2 faces the long side L of the solid electrolytic capacitor 1 formed in a rectangular shape (long side L × short side W). By providing a pair, the distance between the pair of external electrodes 2 is configured to be shorter than the dimension of the long side L.
[0023]
FIG. 4 shows a capacitor element 3 used for the solid electrolytic capacitor 1 shown in FIG. 1 described above. This capacitor element 3 is formed by bonding a rectangular anode body made of a valve metal foil such as aluminum to an insulating resist. The material 4 is separated into an anode part 5 and a cathode part 6 in the short side direction, a dielectric oxide film layer and a solid electrolyte layer (not shown) are formed on the surface of the cathode part 6, and then a cathode made of carbon and silver paste is formed. It is constituted by forming the layer 7.
[0024]
As shown in FIG. 3, a plurality of the capacitor elements 3 configured as described above (three in FIG. 3 are shown, but the present invention is not limited to this). Each of the cathode layers 7 is electrically integrated by connecting a rivet 8 or the like made of a material having a low specific resistance such as silver to the long side of the cathode 7, and then, as shown in FIG. The solid electrolytic capacitor 1 of the present embodiment is formed by integrally covering and further forming a pair of the external electrodes 2 to which the anode portions 5 of the capacitor element 3 and the rivets 8 are respectively connected so as to face each other. Is what it is.
[0025]
5 (a) and 5 (b) are perspective views showing a molding die when integrally covering a plurality of capacitor elements 3 to which the rivets 8 are connected with an insulating exterior resin 9, and main parts thereof. 5 is an enlarged cross-sectional view. In FIG. 5, reference numeral 10 denotes a molding die, and the molding die 10 is provided with a plurality of cavities 11 having a size corresponding to the external dimensions of the solid electrolytic capacitor 1. At the same time, a hole 12 into which the rivet 8 is fitted is provided on the bottom surface of the hollow portion 11, and is connected to the long side of the cathode layer 7 of the capacitor element 3 (capacitor element laminate) in which a plurality of sheets are laminated. The capacitor element laminate is held in the hollow portion 11 by fitting the set rivet 8 into the hole 12, and the molding is performed by filling the exterior resin 9 into the hollow portion 11 in this state. Ah .
[0026]
In the solid electrolytic capacitor according to the present embodiment configured as described above, the distance between the pair of external electrodes 2 contributing to ESL can be made shorter than the long side L, and the conventional electrode wiring by the comb terminal is eliminated. As a result, the ESL can be greatly reduced, and a small and large-capacity solid electrolytic capacitor having a low ESR and a greatly reduced ESL can be realized. When the ESL of the electrolytic capacitor was measured, it was found to be stable at around 2.35 nH, which was extremely low as compared with the conventional product (the results are shown in FIG. 12).
[0027]
In the present embodiment, an example is described in which a roughened surface-treated valve metal foil is used as the anode body constituting the capacitor element 3. However, the present invention is not limited to this. The same operation and effect can be obtained by using a material in which a sintered layer made of valve metal powder is formed on a foil.
[0028]
Also, the rivet 8 in which each of the cathode layers 7 and one of the external electrodes 2 are electrically integrated and connected has been described as a columnar example of a stepped structure, but the present invention is not limited to this. The shape may be a prismatic shape, but it is not preferable that the side connected to the external electrode 2 is made larger than necessary because airtightness may be reduced.
[0029]
(Embodiment 2)
Hereinafter, the second embodiment of the present invention will be described with reference to the second embodiment.
[0030]
6 is a cross-sectional view showing a configuration of a solid electrolytic capacitor according to Embodiment 2 of the present invention, FIG. 7 is a perspective view before the molding, and FIG. 8 is a perspective view showing the capacitor element.
[0031]
6 to 8, reference numeral 13 denotes a capacitor element. The capacitor element 13 is formed by forming a rectangular anode body made of a valve metal foil such as aluminum by using an insulating resist material 14 in the short side direction with the anode part 15. It is constituted by separating into a cathode portion 16, forming a dielectric oxide film layer and a solid electrolyte layer (not shown) on the surface of the cathode portion 16, and then forming a cathode layer 17 made of carbon and silver paste. is there.
[0032]
Further, the anode portion 15 of the anode body is formed in a shape in which a length of about 2/3 in a long side direction is cut out, and the cut portions are alternately inverted so as not to overlap with each other, so that a plurality of capacitors are formed. In a state where the elements 13 are stacked, the respective cathode layers 17 are electrically integrated by connecting a rivet 18 or the like made of a material having a low specific resistance, such as silver, to the long side of the cathode layer 17, and then the insulating sheath is formed. The anodes 15 of the capacitor element 13 and the external electrodes 20 to which the rivets 18 are respectively connected are provided as a pair opposed to the long side of the solid electrolytic capacitor having a rectangular shape. Thus, the distance between the pair of external electrodes 20 is configured to be shorter than the long side.
[0033]
In the solid electrolytic capacitor according to the present embodiment having the above-described configuration, a part of the anode part 15 of the anode body is cut out, and the cut-out parts are alternately inverted so as not to overlap with each other. In this configuration, the notched portion of the anode portion 15 is sufficiently filled with the exterior resin 19, so that a highly airtight solid electrolytic capacitor can be obtained. The ESL of the solid electrolytic capacitor according to the present embodiment is stable at about 2.30 nH, and is extremely low as compared with the conventional product. 12).
[0034]
(Embodiment 3)
Hereinafter, the third embodiment of the present invention will be described with reference to the third embodiment.
[0035]
FIG. 9 is a perspective view showing a configuration of a solid electrolytic capacitor according to Embodiment 3 of the present invention. In FIG. 9, reference numeral 21 denotes a solid electrolytic capacitor; The external electrodes are provided, and the external electrodes 22 are formed by extending a surface (referred to as a lower surface in FIG. 9) serving as a mounting surface to a printed circuit board (not shown) in a direction in which the external electrodes come closer to each other to increase the area. It is.
[0036]
That is, the external electrode 22 on the surface serving as the mounting surface is enlarged to a total dimension C obtained by adding the dimension B to the dimension A as shown in FIG. By extending the area to increase the area, the distance between the external electrodes 22 can be further shortened and the ESL can be further reduced, so that a special effect can be obtained. When the ESL of the capacitor was measured, it was found to be stable at a little less than 2.25 nH, which was extremely lower than that of the conventional product (the results are shown in FIG. 12).
[0037]
(Embodiment 4)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the fourth embodiment.
[0038]
FIG. 10 is a perspective view showing the configuration of a solid electrolytic capacitor according to Embodiment 4 of the present invention. In FIG. 10, reference numeral 23 denotes a solid electrolytic capacitor, and 24 denotes a pair facing the long side of the solid electrolytic capacitor 23. The external electrode 24 is provided so that the height of the external electrode 24 from a surface serving as a mounting surface (not shown in FIG. 10) on a printed board (not shown) is lower than the height of the exterior resin 25 in the same direction. It was done.
[0039]
That is, the height h of the external electrode 24 from the surface serving as the mounting surface is formed to be smaller than the height H of the exterior resin 25 in the same direction as shown in FIG. Due to the reduced height, when the solid electrolytic capacitor 23 of the present embodiment is mounted on a printed circuit board, the solid electrolytic capacitor 23 is provided with the external electrodes 24 on the surface opposite to the mounting surface (indicating the upper surface in FIG. 10). In particular, the electronic component and the like can be prevented from being short-circuited by contact with each other.
[0040]
(Embodiment 5)
Hereinafter, the fifth embodiment of the present invention will be described with reference to the fifth embodiment.
[0041]
FIG. 11 is a perspective view showing a configuration of a solid electrolytic capacitor according to Embodiment 5 of the present invention. In FIG. 11, reference numeral 26 denotes a solid electrolytic capacitor; The external electrodes 28 provided are a pair of external electrodes exposed to a surface (pointing to a lower surface in FIG. 11) opposite to a surface (pointing to a lower surface in FIG. 11) to be a mounting surface to a printed board (not shown). It is an insulating member that insulates the electrode 27.
[0042]
The solid electrolytic capacitor 26 of the present embodiment configured as described above is attached when the solid electrolytic capacitor 26 of the present embodiment is mounted on a printed circuit board, similarly to the solid electrolytic capacitor 23 of the fourth embodiment. This provides a special operation and effect that a phenomenon in which another electronic component or the like contacts the external electrode 27 on the surface opposite to the surface (indicating the upper surface in FIG. 11) and short-circuits can be prevented.
[0043]
【The invention's effect】
As described above, the solid electrolytic capacitor according to the present invention separates a rectangular anode body made of a valve metal into an anode section and a cathode section in the short side direction, and forms a dielectric oxide film layer, a solid electrolyte on the surface of the cathode section. Layer, and a capacitor element in which a cathode layer was sequentially laminated was covered with an exterior resin in a laminated state, and a pair of external electrodes to which the anode and the cathode were respectively connected were provided facing the long side of the exterior resin. With this configuration, the distance between the pair of external electrodes contributing to the ESL can be made shorter than the long side, and electrode routing by the comb terminal can be eliminated, so that the ESL can be greatly reduced. This is a special effect.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a solid electrolytic capacitor according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along a line AA in FIG. 1. FIG. FIG. 5 (a) is a perspective view showing a molding die of the solid electrolytic capacitor. FIG. 5 (b) is a cross-sectional view showing an enlarged main part of the same solid electrolytic capacitor. FIG. 7 is a sectional view showing the configuration of a solid electrolytic capacitor according to Embodiment 2. FIG. 7 is a perspective view showing the same before the molding. FIG. 8 is a perspective view showing the capacitor element. FIG. 9 is a solid electrolytic capacitor according to Embodiment 3 of the present invention. FIG. 10 is a perspective view showing a configuration of a capacitor. FIG. 10 is a perspective view showing a configuration of a solid electrolytic capacitor according to a fourth embodiment of the present invention. FIG. 11 shows a configuration of a solid electrolytic capacitor according to a fifth embodiment of the present invention. FIG. 12 is a perspective view according to an embodiment of the present invention. FIG. 13 is a characteristic diagram showing an ESL characteristic of a solid electrolytic capacitor. FIG. 13 is a perspective view showing a configuration of a conventional solid electrolytic capacitor. FIG. 14 is a cross-sectional view. FIG. 15 is a perspective view showing the capacitor element. Characteristic diagram comparing and showing the ESL characteristics of conventional solid electrolytic capacitors.
1,21,23,26 Solid electrolytic capacitor 2,20,22,24,27 External electrode 3,13 Capacitor element 4,14 Resist material 5,15 Anode part 6,16 Cathode part 7,17 Cathode layer 8,18 Rivet 9, 19, 25 Exterior resin 10 Molding mold 11 Cavity 12 Hole 28 Insulating member

Claims (12)

A capacitor element in which a rectangular anode body made of valve metal is separated into an anode section and a cathode section in the short side direction, and a dielectric oxide film layer, a solid electrolyte layer, and a cathode layer are sequentially formed on the surface of the cathode section. And an insulating exterior resin that covers the capacitor element alone or in a state of lamination of two or more, and is provided to face the long side of the exterior resin, and the anode part and the cathode part are connected respectively. A solid electrolytic capacitor comprising a pair of external electrodes. The rectangular anode body made of a valve action metal is a valve action metal foil having a roughened surface, or a sintered layer made of a valve action metal powder formed on the valve action metal foil. Solid electrolytic capacitor. The solid electrolytic capacitor according to claim 1, wherein the valve metal is one of aluminum, tantalum, niobium, and an alloy thereof. The solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer is made of a conductive polymer. 2. The solid electrolytic device according to claim 1, wherein a part of the anode part of the anode body constituting the capacitor element is cut out, and a plurality of capacitor elements are laminated by alternately turning the front and back so that the cut part does not overlap. Capacitors. 2. The solid electrolytic capacitor according to claim 1, wherein one of the cathode layer and the external electrode of each capacitor element is connected via a silver or copper plate or a rivet. The solid electrolytic capacitor according to claim 1, wherein the external electrode is formed by a plating layer. The solid electrolytic capacitor according to claim 1, wherein surfaces which become mounting surfaces of a pair of external electrodes provided to face each other on the long side are extended in a direction approaching each other to increase the area. 2. The solid electrolytic capacitor according to claim 1, wherein a height from a surface serving as a mounting surface of the pair of external electrodes provided to face the long side is lower than a height of the exterior resin in the same direction. 2. The solid electrolytic capacitor according to claim 1, wherein an insulating material is provided on a pair of external electrodes exposed to face opposite to a face serving as a mounting face. A rectangular anode body made of a valved metal foil subjected to a roughening treatment is separated into an anode part and a cathode part in a short side direction. A capacitor element is manufactured by sequentially forming a laminate, and then a plurality of the capacitor elements are laminated and covered with an insulating external resin. A method for manufacturing a solid electrolytic capacitor, wherein electrodes are provided to face the long side of the exterior resin. The method for manufacturing a solid electrolytic capacitor according to claim 11, wherein after stacking a plurality of capacitor elements, each cathode layer is electrically integrated by connecting a metal rivet to the cathode layer.

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