JPH05283290A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To realize a fine chip-shaped solid electrolytic capacitor whose reliability is high by a method wherein the influence of a stress from the outside is reduced in the solid electrolytic capacitor. CONSTITUTION:One part or the whole of a surface 12 which is the surface of an anode body 1 and which is closest to a cathode terminal 7 is covered with a resin layer 10; an electrolyte layer 3 is formed on the surface of the anode body 1 and the resin layer 10. A stress which is brought from the outside via the cathode terminal 7 can be reduced by using the resin layer.

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 organic conductive compound as an electrolyte.

[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]

An electrolyte layer made of a polymer such as polypyrrole is prepared by, for example, 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 (chemical polymerization). ), A voltage is applied (electrolytic polymerization) while immersing in an electrolytic solution in which pyrrole is dissolved.

However, the polypyrrole produced by such a process is extremely weak in mechanical strength. Damage to solid electrolytes such as polypyrrole leads to fluctuations in electrical characteristics, and in particular, the reformation process can no longer function to repair the damaged part of the oxide film layer on the surface of the anode body, thus avoiding an increase in leakage current. I can't. Then, the damage of the electrolyte layer also causes the damage of the oxide film layer which is the dielectric formed on the surface layer of the anode body, and in combination with the deterioration of the repairability thereof, it is possible to realize and maintain the desired characteristics. It could be difficult.

Such damage of the electrolyte layer is caused by stress when gripping the anode body with a jig or the like, stress when connecting the internal terminal to the conductive layer on the surface of the anode body, and further between the internal terminal and the external terminal. Often caused by stress when connecting. Difficulties in such manufacturing processes increase as the external dimensions of products become smaller, which makes it difficult to adopt complicated terminal structures such as wire bonding and other internal terminals. .

Therefore, a structure in which the conductive layer formed on the surface of the electrolyte layer is directly connected to the external terminal through a conductive adhesive or the like without using the internal terminal can be considered. However, when mounting a solid electrolytic capacitor having such a structure on a printed circuit board or the like, the product may be pinched by a jig such as a chuck for positioning on the printed circuit board and transportation, and the stress at this time is There is a possibility that the conductive layer and the electrolyte layer may directly reach from the external terminal, especially the cathode terminal.

An object of the present invention is to reduce the influence of external stress on a fine chip-type solid electrolytic capacitor and to realize a highly reliable solid electrolytic capacitor.

[0009]

The present invention relates to a solid electrolytic capacitor in which a cathode terminal is connected through an electrically conductive adhesive layer exposed on an end surface of an exterior resin, the surface of the anode body being connected to the cathode terminal. It is characterized in that a part or all of the surfaces closest to each other are coated with a resin layer, and an electrolyte layer made of a solid electrolyte is formed on the surfaces of the anode body and the resin layer.

[0010]

In the solid electrolytic capacitor according to the present invention, the conductive layer formed on the surface of the electrolyte layer is connected to the cathode terminal through the adhesive layer without using the internal terminal. Therefore, the terminal structure is simplified and the manufacturing process thereof can be simplified. Then, by covering the surface of the anode body closest to the cathode terminal, that is, a part or all of the surface most affected by external stress with a resin layer, it is possible to prevent damage to the oxide film layer on this surface. As a result, it is possible to eliminate the influence of the connection of the cathode terminal and the stress when mounting the printed board.

The electrolyte layer is formed on the surface of the anode body and the surface of the resin layer. Therefore, the portion covered with the resin layer does not contribute to the capacity formation, but it is possible to suppress the fluctuation of the characteristics due to the damage of at least the oxide film layer and the electrolyte layer, especially the increase of the leakage current. .

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a conceptual structure of a solid electrolytic capacitor according to an embodiment of the present invention, and FIGS. 2 to 4 are explanatory views for explaining a manufacturing process of the solid electrolytic capacitor according to the embodiment.

In the solid electrolytic capacitor according to this embodiment, as shown in FIG. 1, an oxide film layer 2, an electrolyte layer 3 and a conductive layer 4 are sequentially formed on the surface of a plate-shaped or columnar anode body 1. There is. An anode terminal 6 having a solderable metal layer is connected to one end surface of the anode body 1 by means such as laser welding. On the other hand, the anode terminal 6
The cathode terminal 7 is arranged on the other end face opposite to.
The cathode terminal 7 is electrically connected to the electrolyte layer 2 via a conductive adhesive 5 applied on the surface of the conductive layer 4,
Further, the anode body 1 is sealed from the outside together with the exterior resin 8.

The surface 12 of the surface of the anode body 1 is coated with a resin layer 10 made of epoxy resin or the like. The surface 12 of the anode body 1 is the anode body 1 to which the anode terminal 6 is connected.
Of the resin layer 10 is an end face opposite to the end face of
Covers part or all of 2. The electrolyte layer 3 and the conductive layer 4 are formed on the surfaces of the resin layer 10 and the anode body 1.

That is, in this embodiment, the surface 12 of the anode body 1 is the surface closest to the cathode terminal 7 which is an external terminal, and a part or the whole of this surface 12 is covered with the resin layer 10 to form the cathode terminal 7. The resin layer 10 can reduce the stress caused from the outside through the resin layer 10.

Therefore, the oxide film layer 2 which is the dielectric formed on the surface layer of the anode body 1 can be prevented from being damaged. That is, when the solid electrolytic capacitor according to this embodiment is mounted on a printed circuit board, even if the solid electrolytic capacitor is gripped by a jig such as a chuck used for transportation and positioning, the stress is absorbed by the resin layer 10. , The anode body 1 is not reached.

Further, unlike the conventional case, the cathode terminal 7 is electrically connected to the anode body 1 through the conductive adhesive 5 without using an internal terminal or the like. Poor connection due to impact etc. is less likely to occur.

Next, a process of manufacturing the solid electrolytic capacitor according to the embodiment of the present invention will be described. Anode body 1
Is made of a valve-acting metal such as aluminum, and is formed by cutting out at a desired portion A from a square pole-shaped aluminum wire as shown in FIG. Then, as shown in FIG.
An anode terminal 6 is connected to one end surface of the anode body 1 cut out from an aluminum wire. In this embodiment, strip-shaped concave formed in the base body 9 of the anode terminal 6 _a, 6 _b ~6 _n
A plurality of anode bodies 1 _a , 1 _b to 1 _n were connected to each other by means such as ultrasonic welding or laser welding. Also, the individual anode terminals 6 are
A part of the surface thereof is provided with a solderable metal layer of copper, nickel or the like, and can be used as it is for external connection.

Next, the recess 61 of the anode terminal 6 is filled with the insulating resin layer 20. The resin layer 20 is made of, for example, silicon resin or epoxy resin, and covers the inside of the anode terminal 6 and a part of the anode body 1. Then, the surface of the anode body 1 is subjected to chemical conversion treatment to form the oxide film layer 2 (see FIG. 1). The oxide film layer 2 is made of aluminum oxide whose surface layer of the anode body 1 is oxidized, and serves as a dielectric body of the anode body 1.

Anode body 1 having an oxide film layer 2 formed on the surface
Of the solid electrolytic capacitor according to this embodiment, the surface 12 closest to the cathode terminal 6 is covered with the resin layer 10 made of epoxy resin or the like. Resin layer 10
In coating a, as shown in FIG. 4, dipped into a plurality of anode body 1 _a, 1 _b ~1 _n epoxy resin 11 to melt the end face of which is connected by a base body 9, and dried and solidified.

Then, an electrolyte layer 3 made of polypyrrole is formed on the surfaces of the oxide film layer 2 and the resin layer 10 of the anode body 1. The electrolyte layer 3 is formed by immersing the anode bodies 1 _a , 1 _b to 1 _n connected by the base body 9 in a pyrrole solution containing an oxidizing agent, leaving the anode terminals 6 _a and 6 _{b to} 6 _n, and forming a pyrrole thin film by chemical polymerization, and then the electrolytic solution for electrolytic polymerization by dissolving pyrrole, chemical polymerization and immersed leaving anode terminal 6 _a, 6 _b ~6 _n Similarly, external for electropolymerization A voltage is applied from the electrodes to the surface of the anode body 1 to form a polypyrrole layer, that is, an electrolyte layer 3. In addition,
Since the pyrrole thin film is formed on the surface of the resin layer 10 by chemical polymerization, the polypyrrole layer is also formed by electrolytic polymerization.

Next, a conductive layer 4 made of a carbon paste, a silver paste, a conductive adhesive, etc. is formed on the surface of the electrolyte layer 3. As a result, on the surface of the anode body 1,
As shown in FIG. 1, the electrolyte layer 3 and the conductive layer 4 are sequentially formed on the oxide film layer 2 formed on the surface layer of the anode body 1 to form a laminated structure.

Anode bodies 1 _a , 1 _b to 1 thus obtained
_The cathode terminal 7 is connected to the other end surface of _n , that is, the end surface on which the resin layer 10 is formed, via the conductive adhesive layer 5. Then, the anode terminals 6 _a , 6 _{b to} 6 _n are cut at desired positions, and the single anode body 1 and a part of the anode terminal 6 and the cathode terminal 7 are covered with the exterior resin 8 and shown in FIG. To form such a solid electrolytic capacitor.

In the solid electrolytic capacitor manufactured by the manufacturing process as described above, the resin layer 10 covers the surface 12 of the anode body 1 that is closest to the cathode terminal 7, and also the electrolyte layer 3 and the conductive layer. The layer 4 is formed on the surface of the resin layer 10.

Therefore, in the process of forming the electrolyte layer 3 and the like, for example, in electrolytic polymerization, it is necessary to contact the external electrode with the surface of the anode body 1 to apply a voltage, but the oxide film layer 2 due to the contact of the external electrode. Can be prevented from being damaged. Further, even in the step of connecting the cathode terminal 7, the stress pressing the cathode terminal 7 is absorbed by the resin layer 10 and does not reach the oxide film layer 2 of the anode body 1.

In this embodiment, the resin layer 10 is
One end surface of the anode body 1, that is, the end surface opposite to the end surface to which the anode terminal 6 is connected is covered.
Is to be led out from the lower part of the exterior resin 8, the surface closest to the cathode terminal 7 in this case, that is, the anode body 1
The resin layer 10 is coated on part or all of the lower surface of the.

[0027]

INDUSTRIAL APPLICABILITY As described above, the present invention provides a solid electrolytic capacitor in which a cathode terminal is connected through an electrically conductive adhesive layer exposed on the end face of an exterior resin, in the surface of the anode body and at the cathode terminal. Since a part or all of the surfaces closest to each other are coated with a resin layer, and an electrolyte layer made of a solid electrolyte is formed on the surfaces of the anode body and the resin layer, the cathode layer 7 is used to externally It is possible to prevent the resulting mechanical stress from directly reaching the oxide film layer. Therefore, increase in leakage current due to damage to the oxide film layer, variation in capacitance, etc. are reduced, and stable characteristics can be maintained for a long period of time.

Further, the manufacturing process, especially the stress when forming the electrolyte layer, the conductive layer and the like on the fine anode body and the stress when connecting the cathode terminal can be eliminated as much as possible, and the desired characteristics are provided. It becomes easy to form the anode body with less variation, and as a result, the yield in the manufacturing process is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a conceptual structure of a solid electrolytic capacitor according to an embodiment.

FIG. 2 is an explanatory view illustrating a manufacturing process of a solid electrolytic capacitor according to an embodiment.

FIG. 3 is an explanatory view illustrating a manufacturing process of a solid electrolytic capacitor according to an embodiment.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode body 2 Oxide film layer 3 Electrolyte layer 4 Conductive layer 5 Adhesive layer 6 Anode terminal 61 Recess 7 Cathode terminal 8 Exterior resin 9 Base 10 Resin layer 20 Resin layer

Claims (1)

[Claims] 1. A solid electrolytic capacitor in which a cathode terminal is connected via an electrically conductive adhesive layer exposed on an end surface of an exterior resin, in a part of a surface of an anode body which is the closest to the cathode terminal or A solid electrolytic capacitor, characterized in that the whole is coated with a resin layer, and an electrolyte layer made of a solid electrolyte is formed on the surfaces of the anode body and the resin layer.