JPH06132175A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To achieve a reliable solid electrolytic capacitor with stable electrical characteristics in a fine chip-type solid electrolytic capacitor. CONSTITUTION:An anode body 1 and a cathode body 2 formed on the surfaces of an electrolyte layer 3 consisting of a conductive polymer are laminated in each electrolytic layer 3 for forming a capacitor element 8 and at the same time an anode terminal 5 and a cathode terminal 6 are connected to the exposure surfaces of the anode body 1 and the cathode body 2 which are formed by cutting the end face of a resin layer 7 covering the surface of the capacitor element 8, thus connecting the anode body 1 and the cathode body 2 on the electrolyte layer 3 and simplifying the electrode leading structure.

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, and more particularly to improvement of a solid electrolytic capacitor using an electrolyte composed of an organic conductive compound.

[0002]

2. Description of the Related Art In recent years, electronic components have been made into chips due to demands for miniaturization of electronic equipment and efficiency of mounting on a printed circuit board. Along with this, there are increasing demands for making electrolytic capacitors into chips and reducing their height. Also, due to the diversification of electronic devices, various characteristics are required for chip-type electrolytic capacitors.

Also in the solid electrolytic capacitor, an organic conductive compound such as tetracyanoquinodimethane (TCNQ), polypyrrole, polyaniline or the like is applied to the solid electrolytic capacitor in addition to the solid electrolyte composed of a metal oxide semiconductor such as manganese dioxide. Is proposed. Solid electrolytic capacitors using these organic conductive compounds have higher conductivity than manganese dioxide, etc., and especially polypyrrole etc. are excellent in heat resistance because the electrolyte is polymerized, so it is said to be suitable for chip formation. It is being appreciated.

[0004]

The electrolyte layer made of a conductive polymer such as polypyrrole is formed, for example, by immersing the anode body in a pyrrole solution containing an oxidizing agent to form a pyrrole thin film on the surface of the anode body ( It is generated by applying a voltage (electrolytic polymerization) while immersing it in a solution in which pyrrole is dissolved. Then, an electrode lead-out means is provided on the surface of this electrolyte layer, and the outer surface is covered with an exterior resin or the like.

In the solid electrolytic capacitor having such a structure, when a conductive layer is provided on the surface of the anode body to draw out the electrode from the anode body, in order to prevent short circuit and increase of leakage current,
A strong electrolyte layer was needed. Therefore, electrolytic polymerization was indispensable as a means for generating an electrolyte layer, but since the oxide film layer on the surface of the anode body is an insulator, it is extremely difficult to directly generate an electrolyte layer by electrolytic polymerization. Become. Therefore, so-called pretreatment by the above-mentioned chemical polymerization is required, which makes the manufacturing process complicated.

In both chemical polymerization and electrolytic polymerization, the anode body is immersed in a pyrrole solution. Therefore, the pyrrole solution crawls to an unnecessary portion, causing inconveniences such as a short circuit accident and an increase in leakage current. Therefore, it is necessary to selectively mask the surface of the anode body or to control the liquid level of the pyrrole solution, which complicates the manufacturing process. Particularly in electrolytic polymerization, it is necessary to strictly adjust the applied voltage, the distance between the surface of the anode body and the terminal pin for electrolytic polymerization, and this is not necessarily suitable for mass production.

Further, the polypyrrole produced by the above process is extremely weak in mechanical strength, and it is difficult to form the anode body which is the main body of the chip type solid electrolytic capacitor. For example, when forming an electrolyte layer on a flat plate-shaped anode body and cutting it to form individual anode bodies,
In this cutting step, the polypyrrole layer may be damaged and desired electrical characteristics may not be obtained. This difficulty comes as the product's external dimensions decrease.
It will increase more and more in combination with the refinement of processing accuracy of manufacturing equipment.

In view of the above situation, an object of the present invention is to realize a solid electrolytic capacitor having a stable electric characteristic and a high reliability in a fine chip type solid electrolytic capacitor.

[0009]

SUMMARY OF THE INVENTION In a solid electrolytic capacitor, the present invention relates to a capacitor element in which an anode body and a cathode body having an electrolyte layer made of a conductive polymer formed on each surface are laminated in each electrolyte layer. And the external terminals are connected to the exposed surfaces of the anode body and the cathode body formed by cutting the end surface of the resin layer covering the surface of the capacitor element.

In the present invention, the anode body is made of a valve metal such as aluminum or tantalum and may have a plate shape or a foil shape, but the surface thereof is previously subjected to etching treatment. Further, the number of anode bodies may be one, but a plurality of anode bodies may be laminated and used when there is a margin in external dimensions. As the cathode body, iron, copper, nickel or the like may be used in addition to the valve metal such as aluminum. Examples of the electrolyte layer formed on the surfaces of the anode body and the cathode body include polypyrrole and polyaniline. The method for polymerizing the electrolyte layer made of a conductive polymer includes chemical polymerization, gas phase polymerization, electrolytic polymerization and the like, and it is preferable to form the electrolyte layer by combining these single or plural polymerization methods.

[0011]

In the solid electrolytic capacitor according to the present invention, the oxide film layer 4 and the electrolyte layer 31 are sequentially formed on the surface of the anode body 1, and the electrolyte layer 32 is formed on the surface of the cathode body 2. Then, the anode body 1 and the cathode body 2 are joined at the respective electrolyte layers 31, 32 to form a capacitor element 8 having a laminated structure of the anode body 1 and the cathode body 2. Therefore, by joining the cathode body 2 to the anode body 1, the electrodes of both electrodes can be drawn out.

Further, the surface of the capacitor element 8 formed by laminating the anode body 1 and the cathode body 2 is covered with a resin layer 7,
Further, the end face of the resin layer 7 is cut together with the anode body 1 and the cathode body 2. And the anode body 1 formed as a result
The anode terminal 5 and the cathode terminal 6 are welded to the exposed surface of the cathode body 2. As described above, the anode body 1 and the cathode body 2 are bonded at the electrolyte layers 31 and 32, but the bonding strength is not necessarily strong. However, the resin layer 7 covering the surfaces of the anode body 1 and the cathode body 2 complements the bonding strength complementarily. Further, it becomes unnecessary to directly attach the anode terminal 5 and the cathode terminal 6 to the anode body 1 and the cathode body 2, respectively, and stress in the manufacturing process can be reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a partial sectional view showing a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a conceptual structure of an anode body and a cathode body used in the embodiment. Also, in FIG.
FIG. 4 is a perspective view showing a capacitor element according to an embodiment, and FIG. 4 is a cross-sectional view illustrating a manufacturing process of a solid electrolytic capacitor according to the embodiment.

The anode body 1 is made of a valve metal such as aluminum and is formed in a flat plate shape as shown in FIG. 2 (A). A part of the surface of the anode body 1 is subjected to selective etching treatment and chemical conversion treatment. The oxide film layer 4 is formed. The chemical conversion treatment is carried out by immersing a part of the anode body 1 in a resin or the like in an electrolytic solution for chemical conversion and applying a voltage. The generated oxide film layer 4 is made of aluminum oxide in which the surface layer of the anode body 1 is oxidized, and becomes the dielectric body of the anode body 1. The resin and the like used in the chemical conversion treatment are removed after the anode body 1 is subjected to the chemical conversion treatment.

As shown in FIG. 2B, the cathode body 2 is formed in a flat plate shape like the anode body 1. For the cathode body 2, in addition to a valve metal such as aluminum, a clad material of aluminum and copper or a solderable metal such as copper or nickel may be used.

An electrolyte layer 31 made of a conductive polymer is formed on the surface of the oxide film layer 4 of the anode body 1. In this example, polypyrrole is used as the conductive polymer, and the anode body 1 is immersed in a pyrrole solution containing an oxidizing agent to form a polypyrrole film by chemical polymerization on the surface. When the electrolyte layer 31 is to be a more dense film, chemical polymerization may be performed and then electrolytic polymerization may be performed by immersing the anode body 1 in a solution in which pyrrole is dissolved and applying a voltage.

On the other hand, on the surface of the cathode body 2, as in the case of the anode body 1, an electrolyte layer 32 made of a conductive polymer is formed. The electrolyte layer 32 formed on the surface of the cathode body 2 may be formed by any one of gas phase polymerization, chemical polymerization, electrolytic polymerization, or a combination thereof. Especially in the case of electrolytic polymerization,
Since the oxide film layer 4 which is an insulator is not formed on the surface like the anode body 1, the pretreatment by chemical polymerization is not necessary. Further, in the case of gas phase polymerization or chemical polymerization, a very thin film is produced, but the object of the present invention can be achieved.

The capacitor element 8 is formed by stacking the anode body 1 and the cathode body 2 formed as described above. In this embodiment, the anode body 1 is placed in the gap between the two cathode bodies 2.
Was placed. Further, the anode body 1 and the cathode body 2 are joined at the electrolyte layers 3 of the anode body 1 and the cathode body 2, respectively.

When the anode body 1 and the cathode body 2 are joined, a conductive polymer solution or a suspension in which a conductive polymer is dispersed in a solvent is applied to either the electrolyte layer 31 or the electrolyte layer 32. When the solvent is removed after dropping and adhering the anode body 1 and the cathode body 2 to each other, the second electrolyte layer 3
A layer, which should be called “3”, is generated, and this second electrolyte layer 33 is formed.
Thus, the anode body 1 and the cathode body 2 are joined.

The means for drawing out the electrodes of both electrodes from the capacitor element 8 will be described according to the manufacturing process shown in FIG. 4. First, the resin layer 7 is formed on the surface of the capacitor element 8.
Are covered by means such as molding and potting. Next, the end face of the resin layer 7 is cut along with the anode body 1 and the cathode body 2 along the cut surfaces X ₁ and X ₂ to form exposed surfaces of the anode body 1 and the cathode body 2, respectively. Then, an anode terminal 5 and a cathode terminal 6 for external connection are welded to this exposed surface to draw out the electrode to the outside.

Further, as shown in FIG. 1, the outer periphery of the resin layer 7 coated on the surface of the capacitor element 8 is further coated with the exterior resin 9, and the anode terminal 5 protruding from the bottom surface of the exterior resin 9 is formed. The cathode terminal 6 is bent along the bottom surface of the exterior resin 9.

In this embodiment, an electrolyte layer 31 and an electrolyte layer 32 are formed in advance on the respective surfaces of the anode body 1 and the cathode body 2, and the electrodes of both electrodes are drawn to the outside by joining them. Therefore, especially the electrode on the cathode side can be easily drawn out, and in combination with the structure in which the cathode terminal 6 is connected to the exposed surface provided by cutting the end surface of the resin layer 7, external stress is applied to the internal electrolyte layer 3. It will not reach.

In this embodiment, the surface of the resin layer 7 is further covered with the exterior resin 9. Therefore, the anode terminal 5 and the cathode terminal 6 which are external terminals are both fixed by the exterior resin 9, and the anode body 1 and the cathode body 2 are respectively fixed.
The welding strength in the connection portion with and is complementarily strengthened, and the reliability is improved.

[0024]

As described above, according to the present invention, in a solid electrolytic capacitor, an anode body and a cathode body having an electrolyte layer made of a conductive polymer formed on each surface are laminated in each electrolyte layer to form a capacitor element. In addition to forming an external terminal is connected to the exposed surface of the anode body and the cathode body formed by cutting the end surface of the resin layer coated on the surface of the capacitor element, the anode body and the cathode body are connected. The electrodes can be pulled out by superimposing them. Therefore, the connection structure of the electrodes is simplified, reliability is improved, and miniaturization is extremely easy.

Further, since the anode terminal and the cathode terminal for external connection are welded to the exposed surfaces of the anode body and the cathode body which are provided by cutting the ends of the capacitor element coated with the resin layer,
External stress and stress in the manufacturing process do not reach the inside of the capacitor element, and damage to the electrolyte layer made of a conductive polymer having weak mechanical strength is reduced.
Therefore, desired electrical characteristics, particularly leakage current characteristics, can be stably maintained for a long period of time.

Further, an electrolyte layer is formed on both the anode body and the cathode body, and the layers are superposed, that is, in order to draw out the electrode to the outside without interposing a conductive layer or the like as in the conventional case, a dense electrolyte layer formed by electrolytic polymerization. Since it is not necessary to intervene, the manufacturing process can be greatly simplified, and an increase in leakage current due to electrical stress in the electrolytic polymerization process can be prevented.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a conceptual structure of an anode body and a cathode body used in Examples.

FIG. 3 is a perspective view showing a capacitor element according to an embodiment.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of a solid electrolytic capacitor according to an embodiment.

[Explanation of symbols]

 1 Anode body 2 Cathode body 3 Electrolyte layer 4 Oxide film layer 5 Anode terminal 6 Cathode terminal 7 Resin layer 8 Capacitor element 9 Exterior resin

Claims (1)

[Claims] 1. A resin coating an anode body and a cathode body, each having an electrolyte layer made of a conductive polymer formed on each surface thereof, in each electrolyte layer to form a capacitor element and coating the surface of the capacitor element. A solid electrolytic capacitor, wherein external terminals are connected to exposed surfaces of an anode body and a cathode body formed by cutting the end faces of the layers.