JPH0582400A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To realize a thin solid electrolytic capacitor of high reliability by a method wherein an anode body is joined to a cathode body firmly so as to enhance their hermetically sealed property. CONSTITUTION:In a solid electrolytic capacitor, anode bodies 1 are arranged on both faces of a flat boardlike cathode, body 5, a resin film 9 is pasted on the outer circumferential face of the anode bodies 1 and resin layers 10 are filled into opening end parts of the resin film 9. In the solid electrolytic capacitor, an anode terminal 2 which is welded to end faces of the anode bodies 1 and which is extracted from the opening end part of the resin film 9 is arranged on a plane which is different from the surface of at least the anode bodies 1. A gap is produced between the resin film 9 and the anode terminal 2 and the resin layer is formed in the gap. As a result, the joint strength and the hermetically sealed property of the anode terminal 2 are enhanced.

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 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, 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 both surfaces of the flat cathode body, and a resin film is attached to the outer peripheral surface of the anode body. A structure is conceivable in which the resin layer is attached and a resin layer is formed at the open end of the resin film. According to this structure, the electrolyte layer formed on the surface of the anode body is covered with the anode body itself, and the resin film and the resin layer attached to the outer peripheral surface of the anode body can maintain the internal hermeticity. .

However, in the solid electrolytic capacitor having this structure, the anode terminal is connected to the end face of the bonded anode body by means of ultrasonic welding, laser welding or the like. Dimension is 1mm to 4
Since the length is mm, the welding length of the anode terminal is also 1 m
There is no choice but to be within m to 4 mm. Therefore, sufficient connection strength at the welded portion could not be obtained, and the anode terminal sometimes separated from the anode body.

Further, when the length of the welded portion of the anode terminal is formed to be approximately the same as the height dimension of the bonded anode body, the end face of the anode terminal should be arranged on the same plane as the surface of the anode body. become. Therefore, when a resin film is attached to the surface of the anode body, the resin film and the anode terminal come into contact with each other. Therefore, even if the opening end of the resin film is filled with the resin layer, the portion where the resin film and the anode terminal are in contact with each other is not filled with the resin layer, and the sealing performance is impaired from this portion. Moreover, since the resin layer is not formed on both surfaces of the anode terminal, the connection strength with the anode body becomes more and more weak.

An object of the present invention is to improve the sealing performance inside the anode body in a fine chip type solid electrolytic capacitor and to realize a highly reliable thin solid electrolytic capacitor.

[0011]

According to the present invention, an anode body having an oxide film layer, an electrolyte layer and a conductive layer sequentially formed on the surface thereof is arranged on both sides of a flat cathode body, and the outer peripheral surface of the anode body is arranged. In a solid electrolytic capacitor in which a resin film is attached to the resin film and the opening end of the resin film is filled with a resin layer, the anode terminal which is welded to the end face of the anode body and led out from the opening end of the resin film is at least the surface of the anode body. It is characterized in that it is arranged on a plane different from that and resin layers are formed on both surfaces of the anode terminal.

[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. A resin film 9 is attached to the surfaces of the anode bodies 1a and 1b, and a resin layer 10 is filled in the open ends thereof. Therefore, the inside of the anode body 1 is shielded from the outside air by the anode body 1 itself, the resin film 9, and the resin layer 10.

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 terminals 2 welded to the end faces of the anode bodies 1a and 1b arranged on both sides of the cathode body 5 are arranged on a plane different from at least the surfaces of the anode bodies 1a and 1b. A certain gap is created between the resin film 9 attached to the outer peripheral surfaces of the anode bodies 1a and 1b and the anode terminal 2, and the resin layer 1 is formed at the open end of the resin film 9.
When 0 is filled, the resin layer 10 adheres to both surfaces of the anode terminal 2.

[0015]

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

As shown in FIG. 3, the solid electrolytic capacitor according to the embodiment of the present invention has a resin film 9 attached to the outer periphery thereof, and the resin film 9 filled in the opening end of the resin film 9 and projected from the solidified resin layer 10. The cathode terminal 6 formed is the resin layer 10
It is bent along the bottom.

The anode body 1 to which the resin film 9 is adhered is made of a valve metal such as aluminum and has a recess 8 at a desired position as shown in FIG. This recess 8 is
An opening is formed on one end surface 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 provided in the opening. The inner surface of the concave portion 8 is roughened and then subjected to chemical conversion treatment to form an oxide film layer. The oxide film layer is made of aluminum oxide obtained by oxidizing the surface layer of the anode body 1 made of aluminum, and serves as a dielectric body of the anode body 1.

On the oxide film layer of the anode body 1, an electrolyte layer 3 made of polypyrrole is formed. The polypyrrole layer which is the electrolyte layer 3 is obtained by immersing the anode body 1 in a pyrrole solution containing an oxidant, forming a pyrrole thin film by chemical polymerization on the surface, and then immersing it in an electrolytic solution for electrolytic polymerization in which pyrrole is dissolved. At the same time, a voltage is applied to generate polypyrrole, and the thickness of the generated polypyrrole is several μm to several tens μm.

Further, a conductive layer 4 is screen-printed on the surface of the electrolyte layer 3. Therefore, the surface of the anode body 1,
Particularly, the surface of the concave portion 8 has the electrolyte layer 3 as shown in FIG.
The conductive layer 4 and the conductive layer 4 are sequentially formed into a laminated structure. 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 its end. Then, as shown in FIG. 2, a plurality of anode bodies 1 (anode bodies 1a and 1b) are arranged and joined to both surfaces of the cathode body 5. In this joining, the cathode body 5 is replaced with the anode body 1
Anode bodies 1a and 1b are in contact with the conductive layers 4a and 1b.
It is stored in the concave portion 8 of b. When the anode bodies 1a and 1b are arranged on both sides of the cathode body 5, the anode bodies 1a and 1b are
A conductive adhesive may be additionally applied to the gap between the cathode body 5 and the cathode body 5.

On the end face of the anode body 1, as shown in FIG.
The anode terminal 2 for drawing out the anode is welded. The anode terminal 2 is formed to have an L-shaped cross section, and in this embodiment, a solderable metal, such as copper, is placed at the tip of the printed circuit board facing the wiring pattern.
Using a clad alloy in which aluminum is arranged and joined on the opposite surface, laser welding is performed on the end faces of the joined anode bodies 1a and 1b.

The anode terminal 2 is arranged on a plane different from the surfaces of the anode bodies 1a and 1b. That is, as shown in FIG. 1, the welded portion of the anode terminal 2 is formed shorter than the width dimension at which the anode bodies 1a and 1b are joined, and the surface of the anode terminal 2 does not correspond to the upper and lower surfaces of the anode bodies 1a and 1b. Weld so that they are placed on different planes.

A resin film 9 made of an epoxy resin or the like is wound around and bonded to the outer peripheral surfaces of the anode bodies 1a and 1b at least once. The width dimension of the resin film 9 is formed longer than the longitudinal dimension of the anode bodies 1a and 1b, and the resin film 9 extends from the ends of the anode bodies 1a and 1b.
Will protrude. Further, the anode terminal 2 and the cathode terminal 6 are led out from the open end of the resin film 9. Then, the opening end portion of the resin film 9 that protrudes is filled with the second resin layer 11.

The anode terminal 2 is, as described above, the anode body 1a.
And 1b are arranged on different planes from the upper and lower surfaces. Therefore, as shown in FIG. 1, a gap is formed between the anode terminal 2 and the insulating film 9 attached to the outer peripheral surfaces of the anode bodies 1a and 1b, and the resin layer 10 filled in the open end of the insulating film 9 is formed. Will adhere to both surfaces of the anode terminal 2.

As described above, in the solid electrolytic capacitor according to this embodiment, the anode terminal 2 is welded on a plane different from the surfaces of the joined anode bodies 1a and 1b, so that the anode terminal 2 and the resin film 9 are joined together. The gap is filled with the resin layer 10 to hold the anode terminal 2 firmly. Therefore, the joined state of the anode terminal 2 becomes strong, and sufficient connection strength can be obtained even if the welded portion of the anode terminal 2 is small.

The electrolyte layer 3 is, as shown in FIG.
Electrical contact is made on the surface of the cathode body 5 via the conductive layer 4. Therefore, it is possible to connect without using a means such as bonding with a lead wire as in the conventional case.
It is possible to suppress the stress in this connecting step.

[0027]

As described above, according to the present invention, the oxide film layer,
An anode body in which an electrolyte layer and a conductive layer are sequentially formed on the surface is arranged on both sides of a flat cathode body, and a resin film is attached to the outer peripheral surface of the anode body to form a resin layer at the open end of the resin film. In the filled solid electrolytic capacitor,
The anode terminal, which is welded to the end face of the anode body and led out from the opening end of the resin film, is arranged on a plane different from at least the surface of the anode body, and the resin layer is formed on both sides of the anode terminal. Therefore, the anode body and the anode terminal are fixed to each other not only by the welded portion but also by the resin layer that adheres to both surfaces of the anode terminal. Therefore, even in a fine solid electrolytic capacitor having a height of about 1 mm to 4 mm, the anode terminal can be firmly bonded, and the reliability of the solid electrolytic capacitor is improved.

Further, since the resin layer is formed between the anode terminal and the insulating film attached to the surface of the anode body, the sealing property at this portion is also improved, and the anode terminal can be bent by bending or the like. The sealing performance is not impaired.

Further, the electrolyte layer and the cathode body are connected to each other via the conductive layer. Therefore, mechanical stress on the electrolyte layer can be reduced as compared with the conventional case where the electrode is pulled out by a lead wire or the like.

[Brief description of drawings]

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

FIG. 2 is an exploded perspective view showing a solid electrolytic capacitor according to an embodiment.

FIG. 3 is a perspective view showing an external shape of a solid electrolytic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION 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 9 Resin film 10 Resin layer

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01G 9/10 D 7924-5E

Claims (1)

[Claims] 1. An anode body on which an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed is arranged on both sides of a flat cathode body, and a resin film is attached to the outer peripheral surface of the anode body to form a resin. In a solid electrolytic capacitor in which the opening end of the film is filled with a resin layer, the anode terminal, which is welded to the end face of the anode body and led out from the opening end of the resin film, is arranged at least on a plane different from the surface of the anode body. , Solid electrolytic capacitors with resin layers formed on both sides of the anode terminal.