JPH05144686A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve tight seal properties of the inside of an anode body in a fine chip type solid electrolytic capacitor. CONSTITUTION:The title capacitor is manufactured in the following manner. A plurality of planar type anode bodies 1a and 1b are bonded to each other on the surfaces. A metal foil 20 is welded on the end surface of each of the anode bodies 1a and 1b. An oxide coating film layer, an electrolyte layer, and a conductive layer 4 are formed in order on inner surfaces of the anode bodies 1a and 1b which are opened via the metal foil 20. A plurality of the anode bodies 1a and 1b are again bonded via a planar type cathode body 5.

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 both sides of a flat cathode body is considered. According to this structure, the electrolyte layer formed on the surface of the anode body is covered with the anode body itself, and the anode body forms an exterior for maintaining the internal hermeticity, and further, the mechanical strength as a chip-type electronic component is improved. You can stick.

However, in the solid electrolytic capacitor having this structure, as the anode body, an oxide film layer, an electrolyte layer, etc. are selectively formed on a substrate made of aluminum or the like, and these are individually separated. In the anode body formed by such a manufacturing process, the oxide film layer or the like may be damaged due to the stress in the separation process, which tends to cause the deterioration of electrical characteristics, especially the increase of leakage current. . Further, even when a plurality of anode bodies are joined together, the joining positions are minutely displaced and a gap is generated, which sometimes makes it difficult to maintain the internal hermeticity.

Further, even if the position of each anode body is adjusted after joining in order to correct this minute deviation, the oxide film layer inside may be damaged by this adjustment, and the above-mentioned anode In order to compensate for the decrease in sealing performance due to body displacement, even when the joined anode body is ultrasonically welded,
There is also a problem that the internal electrolyte layer and oxide film layer are damaged even by vibration such as ultrasonic welding.

An object of the present invention is to provide a manufacturing method for obtaining a highly reliable thin solid electrolytic capacitor in a fine chip type solid electrolytic capacitor, in which the sealing property inside the anode body is improved.

[0011]

According to the present invention, in a method for manufacturing a solid electrolytic capacitor, a plurality of anode bodies are joined on the surface thereof, and a metal foil is welded to the end face of each anode body, and then the metal foil is interposed. The present invention is characterized in that an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed on the inner surface of the opened anode body, and a plurality of anode bodies are joined again through a flat cathode body.

[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 anode body 1 itself. In addition, the electrolyte layer 3
Are 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. Also,
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.

Anode body 1 (anode bodies 1a and 1b)
Is pre-joined by a metal foil 20 to be welded to its end face, and thereafter, an oxide film layer, an electrolyte layer 3 and a conductive layer 4 are sequentially formed on the surface in an open state through the metal foil 20, and again through the cathode body 5. The anode bodies 1a and 1b are joined. Therefore, the joining state of the anode bodies 1a and 1b after forming the electrolyte layer 3 is stable, and it is not necessary to adjust the joining position.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a perspective view showing a manufacturing process in an embodiment of the present invention and a sectional view showing a conceptual structure of a solid electrolytic capacitor according to the embodiment in FIG. FIG. 4 is a perspective view showing another embodiment of the present invention.

The anode body 1 is formed by separating a plate-shaped base body made of a valve metal such as aluminum into a predetermined shape, and as shown in FIG. 1B, a recess 8 is formed at a desired position. And an opening is formed in one end surface of the anode body 1. Further, a resist layer 7 for preventing a short circuit between the anode body 1 and the cathode terminal 6 is provided in this opening.

The anode bodies 1a and 1b are joined so that the recesses 8 face each other, and as shown in FIG. 1 (A), they are placed on the surface of the metal foil 20 and ultrasonically welded. The metal foil 20 may be any one that is suitable for welding with the anode bodies 1a and 1b. For example, in this embodiment, an aluminum foil or the like is used.

Next, as shown in FIG. 1 (B), the joined anode bodies 1a and 1b are opened, and in this state, the inner surface of the recess 8 is roughened, and then chemical conversion treatment is performed to form an oxide film. Form the layers. The oxide film layer is made of aluminum oxide obtained by oxidizing the surface layers of the anode bodies 1a and 1b made of aluminum, and serves as the dielectric body of the anode bodies 1a and 1b.

With the anode bodies 1a and 1b connected by the metal foil 20, an electrolyte layer 3 made of polypyrrole is formed on the oxide film layer formed in the recess 8. The polypyrrole layer which is the electrolyte layer 3 is obtained by immersing the anode bodies 1a and 1b in a pyrrole solution containing an oxidant, forming a pyrrole thin film by chemical polymerization on the surface, and then dissolving the pyrrole in an electrolytic solution for electrolytic polymerization. It is formed by immersing and applying a voltage, and the thickness of the generated polypyrrole is several μm to several tens μm. In this polymerization step, masking may be selectively performed with a resin layer or the like so that only the concave portion 8 is exposed to the outside if necessary.

The conductive layer 4 is formed on the surface of the electrolyte layer 3.
Screen print. As a result, the anode bodies 1a and 1b
As shown in FIG. 3, the surface of the concave portion 8, especially the surface of the concave portion 8,
It has a laminated structure in which the electrolyte layer 3 and the conductive layer 4 are sequentially formed. 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.

Next, as shown in FIG. 1B, the cathode body 5 is placed on the anode body 1a or 1b. Cathode body 5
Consists of flat aluminum or its alloy,
A cathode terminal 6 made of a solderable metal layer such as copper is integrally formed at the end portion. And FIG.
As shown in (A), a plurality of anode bodies 1a and 1b are
It joins again via the metal foil 20. By this bonding, the cathode body 5 comes into contact with the conductive layers 4 of the anode bodies 1a and 1b. When the anode bodies 1a and 1b are joined via 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.

Further, the anode terminals 2 are ultrasonically welded to the end faces of the anode bodies 1a and 1b to obtain a solid electrolytic capacitor as shown in FIG. 2 (B). The anode terminal 2 is formed to have an L-shaped cross section. In this embodiment, a solderable metal such as copper is placed on the tip of the printed circuit board facing the wiring pattern, and aluminum is placed on the opposite surface. The clad alloy is arranged and joined.

As described above, in the method for manufacturing a solid electrolytic capacitor according to this embodiment, a plurality of anode bodies 1a and 1 are previously prepared.
Since the oxide film layer, the electrolyte layer 4 and the like are formed in the state where b is joined by the metal foil 20, the oxide film layer is not damaged in the step of separating the anode bodies 1a and 1b as in the conventional case.
In addition, after the anode bodies 1a and 1b are previously joined, the metal foil 2
Since it is opened via 0, the electrolyte layer 3 and the like are formed, and then joined again, the joined state becomes good, and the position adjustment after joining is not necessary.

When a plurality of anode bodies 1a and 1b are welded to the metal foil 20 to be joined, they are placed on a continuous metal foil 21 and welded intermittently or continuously, as shown in FIG. You may. In this case, the anode bodies 1a and 1b in a plurality of combinations connected by the metal foil 21 can be supplied as a continuous body, which simplifies the manufacturing process.

[0024]

As described above, according to the present invention, in the method for manufacturing a solid electrolytic capacitor, a plurality of flat plate-shaped anode bodies are joined on the surface thereof, and a metal foil is welded to the end faces of the respective anode bodies, and then the metal foil Since an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed on the inner surface of the anode body opened through the foil, and a plurality of anode bodies are joined again through the flat cathode body, a plurality of Even if the anode body is joined via the cathode body, the joined state becomes good, and the electrolyte layer and the like inside can be sealed from the outside air.

Further, since the anode body itself is separated from the substrate in advance and then the oxide film layer or the like is formed, the oxide film layer is not damaged in the separation step, and the electrical characteristics such as leakage current are improved. There is no impact.

[Brief description of drawings]

FIG. 1 is a perspective view showing a manufacturing process in an embodiment of the present invention.

FIG. 2 is a perspective view showing a manufacturing process in an embodiment of the present invention.

FIG. 3 is a sectional view showing a conceptual structure of a solid electrolytic capacitor according to an embodiment.

FIG. 4 is a perspective view showing another embodiment of the present invention.

[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 20 Metal foil 21 Metal foil

Claims (1)

[Claims] 1. A plurality of flat plate-shaped anode bodies are joined on the surface thereof, and a metal foil is welded to the end surface of each anode body, and then an oxide film layer is formed on the inner surface of the anode body opened through the metal foil, A method for manufacturing a solid electrolytic capacitor, in which an electrolyte layer and a conductive layer are sequentially formed, and a plurality of anode bodies are joined again via a flat cathode body.