JPH05121279A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve hermeticalness inside an anode in a title capacitor of fine chip form. CONSTITUTION:In this capacitor that is a couple of flat plate anodes 1a, 1b with an oxide film layer, an electrolytic layer 3, and a conductor layer 4 formed one after another on one surface and a flat plate cathode 5 via the conductor layer 4 of the anodes 1a, 1b, the anodes 1a, 2b are made of a clad material comprising an aluminum layer 10 and an aluminum alloy layer 11, and an aluminum layer 10 is arranged on the surface where at least an oxide film layer is formed, whereby workability of the anodes 1a, 1b improve, strain of the surface of the anodes 1a, 1b can be suppressed.

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 a method for manufacturing the same, and more particularly to improvement of a chip type solid electrolytic capacitor using 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.

In recent years, tetracyanoquinodimethane (T
Application of organic conductive compounds such as CNQ) and polypyrrole to solid electrolytic capacitors has been proposed. Solid electrolytic capacitors using these organic conductive compounds,
Compared with conventional solid electrolytes made of metal oxide semiconductors such as manganese dioxide, it has a higher conductivity, and polypyrrole is said to be ideal for chipping because it has excellent heat resistance because the electrolyte is polymerized. .

[0004]

This polypyrrole is
It is formed on the surface of the anode body by chemical polymerization, electrolytic polymerization or vapor phase polymerization of pyrrole. However, the mechanical strength of polypyrrole itself is weak, and the lead wire or the like sometimes breaks the electrolyte layer during the connecting step depending on the lead-out structure of the electrode. Alternatively, mechanical stress on the lead wire after the connection process affects the electrolyte layer,
It may be difficult to obtain desired characteristics.

On the other hand, the electrical characteristics of this polypyrrole tend to fluctuate due to moisture. for that reason,
The electrolyte layer made of polypyrrole needs to be sealed from the outside air.

[0006] Such a problem is that the outer surface of the capacitor body is formed by means such as dip or injection molding.
It can be solved by covering with a synthetic resin layer. However, this exterior resin layer hinders the downsizing and height reduction of solid electrolytic capacitors.
It is difficult to make the height dimension of about mm to 4 mm. In addition, since a minute gap may be formed on the joint surface between the exterior resin layer and the terminal, it is not always possible to obtain high sealing accuracy, that is, desired moisture resistance performance, even by resin molding.

Therefore, a structure in which an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed on the surface of the anode body and the anode body is arranged on the surface or both surfaces of the flat cathode body is conceivable.
According to this structure, the electrolyte layer formed on the surface of the anode body is covered by the anode body itself and the cathode body, and the anode body forms an exterior for maintaining the internal hermeticity. It is possible to maintain the desired strength.

However, in the solid electrolytic capacitor having this structure, although the base body made of aluminum is finely processed to form the anode body, aluminum having high purity is used as the anode body because it is necessary to eliminate the influence of impurities on the solid electrolyte. Used as. Therefore, when the anode body is formed by cutting, punching, or the like from a base made of high-purity aluminum, which is generally softer than other metals, distortion of the surface of the anode body may occur due to the high spreadability of aluminum. was there. Therefore, even if such an anode body is arranged on one side or both sides of the cathode body to form an exterior structure, a gap is created in the joint surface between the anode body and the cathode body or the anode bodies, and the internal hermeticity is maintained. Becomes difficult.

[0009] Such distortion of the surface of the anode body also affects the connection strength of the anode terminal to be welded to the anode body, leading to poor connection, separation from the anode body, and the like. Further, the electrolyte layer may be damaged due to the distortion of the anode body, and desired electrical characteristics may not be obtained.

An object of the present invention is to provide a highly reliable thin solid electrolytic capacitor which improves the sealing property inside the anode body in a fine chip type solid electrolytic capacitor.

[0011]

According to the present invention, a flat plate-shaped anode body in which an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed on one surface, and a flat plate-shaped cathode body are provided. In a solid electrolytic capacitor joined via layers, the anode body is made of a clad material provided with an aluminum layer and an aluminum alloy layer, and the aluminum layer is arranged at least on the surface where an oxide film layer is formed. .

[0012]

As shown in the drawing, the surface of the anode body 1 is covered with the flat cathode body 5 and the separately prepared anode body 1b. Therefore, the inside of the anode body 1 is shielded from the outside air by the cathode body 5 or the anode body 1 itself.

The electrolyte layer 3 is connected to the surface of the cathode body 5 via the conductive layer 4. Therefore, mechanical stress applied to the electrolyte layer 3 is reduced as compared with the case where the lead wire is connected to the conductive layer 4 by means such as wire bonding or soldering. Further, the stress due to bending of the lead wire or the like is not concentrated on a part, and damage to the electrolyte layer 3 can be suppressed to a minimum.

The anode body 1 used in the solid electrolytic capacitor according to the present invention is a clad material obtained by joining the aluminum layer 10 and the aluminum alloy layer 11, for example, aluminum-copper alloy, aluminum-manganese alloy as the aluminum alloy layer 11, Aluminum-magnesium alloy, aluminum-silicon alloy, etc., and high purity aluminum of 99.00% to 99.99% is used as the aluminum layer 10. Therefore, on the surface where the electrolyte layer 3 is formed, the high-purity aluminum layer 10 eliminates the influence of impurities on the electrolyte layer 3, and at the same time, the anode body 1
The mechanical strength of the aluminum alloy layer 11 is improved by the aluminum alloy layer 11.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a manufacturing process of the solid electrolytic capacitor according to the embodiment. 3 is an exploded perspective view showing a solid electrolytic capacitor according to an embodiment, and FIG.
FIG. 3 is a sectional view showing a conceptual structure of a solid electrolytic capacitor according to an example.

As shown in FIG. 3, the anode body 1 is provided with a recess 8 at a desired position, and an oxide film layer is formed on the inner surface of the recess 8 by roughening treatment and chemical conversion treatment.
The recess 8 has an opening at one end face of the anode body 1, and a resist layer 7 for preventing a short circuit between the anode body 1 and the cathode terminal 6 is formed in this opening.

The anode body 1 is made of a clad material in which an aluminum layer 10 which is a valve metal and an aluminum alloy layer 11 are joined. As the aluminum alloy layer 11, for example, aluminum-copper alloy, aluminum-manganese alloy, aluminum-magnesium alloy, aluminum-silicon alloy, etc., and as the aluminum layer 10, high purity aluminum of 99.00% to 99.99% is used. However, in this embodiment, the clad material in which the aluminum layer 10 having a thickness of 300 μm and the aluminum alloy layer 11 made of an aluminum-copper alloy having a thickness of 700 μm are joined is used.

The manufacturing process of the anode body 1 will be described. As shown in FIG. 2A, a plurality of recesses are formed at desired locations on a base body 20 made of a clad material obtained by joining an aluminum layer 10 and an aluminum alloy layer 11. 8 is formed by means of pressing, cutting, etching or the like. Next, a resist layer 7 made of a synthetic resin is applied to a part of the recess 8 by means of screen printing or the like (FIG. 2 (B)), and an oxide film layer is formed on the inner surface of the recess 8 by a roughening treatment and a chemical conversion treatment. Form. This oxide film layer is made of aluminum oxide whose surface layer surface of the aluminum layer 10 is oxidized, and serves as a dielectric. Further, an electrolyte layer 3 made of polypyrrole is formed on this oxide film (FIG. 2).
(C)). The polypyrrole layer, which is the electrolyte layer 3, is the base 2
0 is immersed in a pyrrole solution containing an oxidant, a pyrrole thin film is formed on the surface by chemical polymerization, and then immersed in an electrolytic solution for electrolytic polymerization in which pyrrole is dissolved, and a voltage is applied to generate. Next, the conductive layer 4 is screen-printed on the surface of the electrolyte layer 3, and the base body 20 is cut at desired positions, for example, X-rays and Y-lines to obtain the anode body 1 (anode body 1b) as shown in FIG. obtain.

The anode body 1 manufactured in this manner has a laminated structure in which the electrolyte layer 3 and the conductive layer 4 are sequentially formed on the surface thereof, particularly in the recesses 8, as shown in FIG. The conductive layer 4 may have either a multi-layered structure including a carbon paste, a silver paste, a conductive adhesive, or the like, or a single-layer structure including a conductive adhesive containing metal powder having good conductivity.

The cathode body 5 is made of plate-shaped aluminum or its alloy, and a cathode terminal 6 made of a solderable metal layer such as copper is integrally formed at an end portion thereof. Then, as shown in FIG. 3, a plurality of anode bodies 1 (anode bodies 1a and 1b) are arranged on both surfaces of the cathode body 5. For joining the anode bodies 1a and 1b to the cathode body 5, the cathode body 5 is housed in the recess 8 of the anode bodies 1a and 1b so that the conductive layer 4 of the anode bodies 1a and 1b and the cathode body 5 are in contact with each other.
When the anode bodies 1a and 1b are arranged on both sides of the cathode body 5, a conductive adhesive may be additionally applied to the gap between the anode bodies 1a and 1b and the cathode body 5.

The anode terminals 2 are laser-welded or ultrasonic-welded to the end faces of the anode bodies 1a and 1b. In this embodiment, the anode terminal 2 is made of a clad material in which a solderable metal such as copper is arranged at the tip of the printed circuit board facing the wiring pattern, and aluminum is arranged on the opposite surface of the clad material.

As described above, in the solid electrolytic capacitor according to this embodiment, the anode bodies 1a and 1b are made of the aluminum layer 1.
0 and an aluminum alloy layer 11 are joined together, a high-purity aluminum layer 10 is disposed on the surface where the electrolyte layer 3 is formed to eliminate the influence of impurities and to face the outer surface of the aluminum alloy layer. 11 improves the mechanical strength of the anode body 1 itself. Therefore, even in the cutting step as shown in FIG.
Distortion or the like is less likely to occur on the surface of the anode body 1, and the joint surfaces of the anode body 1a and the anode body 1b arranged on both sides of the cathode body 5 are brought into close contact with each other, so that the internal hermeticity can be improved.

[0023]

As described above, according to the present invention, the oxide film layer,
In a solid electrolytic capacitor in which a flat plate-shaped anode body in which an electrolyte layer and a conductive layer are sequentially formed on one surface and a flat plate-shaped cathode body are joined via a conductive layer of the anode body, the anode body is an aluminum layer. And an aluminum alloy layer, and is characterized in that the aluminum layer is disposed on at least the surface on which the oxide film layer is formed. Therefore, it is possible to form a strong anode body with the aluminum alloy layer having high hardness. You can Therefore, the distortion of the surface of the anode body due to the mechanical stress in the manufacturing process can be suppressed, and even if the anode bodies are arranged on both surfaces of the cathode body, the gap between the joint surfaces is reduced. Therefore, the internal sealing property is improved and the deterioration of the electrolyte layer due to moisture or the like is suppressed, so that the electrical characteristics can be maintained for a long period of time.

Further, since the distortion of the surface of the anode body is reduced, the joining state with the anode terminal to be welded to the end face of the anode body is also improved, and the anode terminal can be prevented from coming off from the anode body. Further, also in the step of processing the base body to be the anode body, the workability is improved because the overall malleability is reduced by the aluminum alloy layer.

[Brief description of drawings]

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

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

FIG. 3 is an exploded perspective view showing a solid electrolytic capacitor according to an embodiment.

FIG. 4 is a sectional view showing a conceptual structure of a solid electrolytic capacitor according to an embodiment.

[Explanation of symbols]

 1 Anode body 2 Anode terminal 3 Electrolyte layer 4 Conductive layer 5 Cathode body 6 Cathode terminal 7 Resist layer 8 Recess 10 Aluminum layer 11 Aluminum alloy layer 20 Base

Claims (1)

[Claims] 1. A solid electrolysis in which a flat plate-shaped anode body in which an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed on one surface and a flat plate-shaped cathode body are joined via a conductive layer of the anode body. In the capacitor, the anode body is made of a clad material having an aluminum layer and an aluminum alloy layer, and the aluminum layer is disposed on at least the surface on which the oxide film layer is formed.