JP2955312B2 - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor, and more particularly to an improvement of a chip type solid electrolytic capacitor using an organic conductive compound.

[Conventional technology]

In recent years, there has been a demand for miniaturization of electronic devices and more efficient mounting on a printed circuit board, etc., so that electronic components have been formed into chips. Along with this, there has been an increasing demand for chipping of electrolytic capacitors, and various proposals have been made.

However, in the case of an electrolytic capacitor, particularly an electrolytic capacitor using an electrolytic solution as an electrolyte, it is necessary to seal the electrolytic solution in a certain storage space. Generally, such sealing is performed by attaching a sealing body made of elastic rubber to an opening of a bottomed cylindrical outer case containing a capacitor element.

When reducing the size of an electrolytic capacitor having such a sealed structure, it is necessary to simultaneously reduce the size of the sealed structure.However, in order to maintain a sufficient degree of sealing, a certain space for mounting a sealing body, and It is essential to provide a means, which makes it difficult to reduce the size of the electrolytic capacitor. Therefore, although various proposals have been made for chip type electrolytic capacitors on the premise of miniaturization of the electrolytic capacitor body, for example, the height dimension from the printed circuit board is 10 mm.
However, it is extremely difficult to realize a chip-type electrolytic capacitor of about 1 mm to 3 mm, which is equivalent to the outer diameter of a ceramic capacitor.

On the other hand, a solid electrolytic capacitor that does not use an electrolytic solution generally has a solid electrolyte layer made of, for example, manganese dioxide or the like formed on an anode body made of tantalum or the like having an oxide film layer formed on its surface, and further has a carbon paste and It has a configuration in which a conductive layer made of silver paste or the like is formed.

Such a solid electrolytic capacitor is relatively easy to miniaturize because the electrolyte is solid, and can be made into a chip.

However, the capacitance range of the conventional solid electrolytic capacitor is limited to about 0.1 to 10 μF. Further, although its impedance characteristic is superior to that of an electrolytic capacitor using an electrolytic solution, it is still insufficient compared with a ceramic capacitor or the like, and the cost increases when tantalum is used for the anode body.

[Problems to be solved by the invention]

By the way, recently, tetracyanoquinodimethane (TCNQ),
There has been proposed one in which an organic conductive compound such as polypyrrole is applied to a solid electrolytic capacitor. For example, a solid electrolytic capacitor using polypyrrole is disclosed in
-158829, JP-A-63-173313, JP-A-1-228122
JP-A-1-232712, JP-A-1-231605, JP-A-1-243510, JP-A-1-260809, JP-A-1-268111
And the like.

These solid electrolytic capacitors have higher electrical conductivity than conventional solid oxides made of metal oxide semiconductors, so they have particularly high-frequency impedance characteristics and do not need to seal liquid to the electrolytic capacitor body. It is easy to reduce the size.

However, TCNQ complexes tend to lack chemical stability, and are particularly poor in heat resistance. Therefore, in the case of a solid electrolytic capacitor in which an electrolyte layer made of a TCNQ complex is formed on the surface of an anode body made of aluminum, it may be denatured by a soldering temperature that usually rises to around 260 ° C, which is not suitable for chip formation. Met.

A solid electrolytic capacitor using polypyrrole as an electrolyte is said to be excellent in heat resistance because the electrolyte is polymerized, and is most suitable for chip formation.

This polypyrrole is formed on the surface of the anode body by chemical polymerization, electrolytic polymerization or gas phase polymerization of pyrrole. However, the mechanical strength of the polypyrrole itself is low, and the polypyrrole itself may be damaged by mechanical stress such as twisting of the anode body serving as a base or external pressure.

When a general chip-type electronic component is surface-mounted on a printed circuit board, it is transferred from a supply source and attached by a jig such as a suction nozzle. At this time, it is said that a weight of about 1 kg is applied to the component body by the pressing of the suction nozzle. In the case of ordinary electronic components, the polypyrrole layer, which can sufficiently withstand this degree of overload due to the exterior resin, has poor mechanical strength, is used as the electrolyte layer. The nozzle may be damaged by pressing.

Further, the properties of polypyrrole change due to moisture. Therefore, an exterior structure with improved moisture resistance is required.

Such a demand can be satisfied by forming a polypyrrole layer on a strong block-shaped anode body and coating the exterior with a thick exterior resin as in a conventional solid electrolytic capacitor. However, miniaturization of the entire component is hindered, and as described above, it has been difficult to make the external dimensions comparable to those of the ceramic capacitor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable chip type having sufficient rigidity as a chip type electronic component and not being damaged even when the electrolyte layer has a weak mechanical strength when mounted on a printed circuit board. An object of the present invention is to provide a solid electrolytic capacitor.

[Means for solving the problem]

The present invention provides, in a solid electrolytic capacitor, a plurality of anode bodies each having an oxide film layer, an electrolyte layer, and a conductive layer sequentially formed on a surface thereof, such that the conductive layers are opposed to each other. It is characterized in that a cathode body is arranged in the gap.

Further, as a manufacturing method thereof, while forming an electrolyte layer and a conductive layer on one surface of the anode body, after bonding a plurality of anode bodies with a cathode body in contact with the conductive layer,
At least the gap between the anode bodies is covered with an insulating layer, and the terminal portion and the cathode body previously drawn out of the anode body are bent along the outer surface of the anode body.

(Operation)

As shown in the drawings, in the present invention, a mechanically fragile electrolyte layer 3, for example, a polypyrrole layer is a plate-like strong anode body.
1a and 1b, the electrolyte layer 3 can be protected from mechanical stress, atmospheric moisture, and the like.
The exterior resin 8 can be formed thin. Therefore, it is possible to simultaneously satisfy the two requirements for reducing the size of the component while improving the mechanical strength of the component itself.

Further, the cathode body 5 is sandwiched between a plurality of anode bodies 1a and 1b. Therefore, the connection between the conductive layer 4 and the cathode body 5 is improved, and the terminal structure is simplified. Furthermore, the cathode body 5
Since the electrolyte layers 3 are arranged on both sides of the substrate, the capacity can be increased.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. 3 and 5 are perspective views illustrating a method for manufacturing a solid electrolytic capacitor according to the present invention, FIG. 4 is a conceptual diagram illustrating an electrolyte layer forming process during the process, and FIG. It is a perspective view showing an example.

The anode body 1 is made of plate-like aluminum or its alloy as shown in FIG. A resist layer 2 made of an insulating material is selectively formed on one surface of the anode body 1 by screen printing (FIG. 4A). Next, the exposed aluminum surface 9 is roughened to increase the surface area, and a dielectric oxide film layer made of aluminum oxide is formed by electrolytic oxidation. Then, a pyrrole thin film is formed by chemical polymerization in a pyrrole solution containing an oxidizing agent, and then the anode body 1 is immersed in an electrolytic solution for electrolytic polymerization in which pyrrole is dissolved in a solvent for electrolytic polymerization, and a voltage is applied. Then, an electrolyte layer 3 composed of a polypyrrole layer of several μ to several tens μ is formed on the surface (FIG. 4 (b)).

Further, a conductive layer 4 is screen-printed on the surface of the electrolyte layer 3 (FIG. 4 (c)). The conductive layer 4 may have either a multilayer structure made of a carbon paste and a silver paste, or a single layer structure made of a conductive adhesive containing a metal powder having good conductivity.

Thus, the anode body 1 in which the dielectric layer, the electrolyte layer 3 and the conductive layer 4 sequentially formed on the surface are selectively formed by the resist layer 2 is cut by a dicing saw, a high-pressure jet water stream, a laser beam, or the like. Then, as shown in FIG. 5, an anode body 1a in which the electrolyte layers 3 (conductive layers 4) arranged at selected positions are arranged in a straight line is formed. Then this continuous anode body
A cathode body 5 made of a solderable metal, for example, copper or the like is placed on the conductive layer 4 of 1a. At this time, a conductive adhesive may be applied to the surface of the cathode body 5 in order to secure the joining between the cathode body 5 and the conductive layer 4.

Then, in the same manner as the anode body 1a, an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed on one surface, and the anode body 1b in which these electrolyte layers and the like are linearly arranged at a selected position. Separately prepared and superposed on the anode body 1a on which the cathode body 5 is mounted. Next, the conductive layer 4 of each anode body 1a, 1b is
The anode body 1 is brought into contact with the cathode body 5 and cut and separated from the plurality of facing electrolyte layers 3 as one unit. Further, an anode terminal 6 for extracting an electrode made of a metal such as copper which can be soldered is connected to an end face of each of the separated anode bodies 1 by means of ultrasonic welding, laser welding or the like, as shown in FIG. Such a solid electrolytic capacitor is formed.

As shown in FIG. 6, the surface of the anode body 1 is covered with a thermosetting exterior resin 8, and the anode terminal 6 and the cathode body 5 projecting from the end surface of the anode body 1 are attached to the surface of the exterior resin 8. To obtain a solid electrolytic capacitor provided with an exterior structure made of a synthetic resin.

In the solid electrolytic capacitor obtained by such a manufacturing method, as shown in FIG. 2, the cathode body 5 is sandwiched between a plurality of electrolyte layers via a conductive layer, so that the connection structure is simple and When the cathode body 5 is formed of a lead frame, mass productivity is improved. Further, unlike the related art, the connection portion between the conductive layer and the cathode body 5 is not directly covered with the exterior resin. Therefore, it is not necessary to consider the connection state between the terminal portion and the cathode body as in the related art. Therefore, in addition to resin sealing such as potting, the exterior resin 8 is formed on the surface of the anode body 1 by means such as molding and injection.
Can be coated, the dimensional accuracy of the appearance is improved, the polarity indication on the exterior is easy and the quality is high, and the resin coating process itself is simplified.

Further, in the solid electrolytic capacitor manufactured by the above-described manufacturing process, since the electrolyte layer 3 is sandwiched at least by the anode body 1, it is not directly subjected to external mechanical stress.

As for the sealing of the electrolyte layer 3 itself, as shown in FIG. 1, at least a gap between the plurality of anode bodies 1 has a function of shielding outside air, for example, a sealing resin layer 7 made of an epoxy resin or the like. If the adhesion between the anode body 1 and the resin layer 7 is good, it is not necessary to cover the entire surface of the anode body 1 with the exterior resin 8 as shown in FIG. Therefore, the overall external dimensions can be further reduced.

In the embodiment, the cathode member 5 is made of a metal such as copper that can be soldered, but a clad material of aluminum and a solderable metal such as copper may be used. In addition, one surface of the cathode body 5, in particular, a surface facing the anode body 1 may be subjected to insulation treatment such as coating with a resin, and the folded cathode body 5 may be adhered to the anode body 1.

〔The invention's effect〕

As described above, the present invention provides, in a solid electrolytic capacitor, a plurality of anode bodies each having an oxide film layer, an electrolyte layer, and a conductive layer formed sequentially on a surface thereof, such that the conductive layers are opposed to each other. Since the cathode body is disposed in the gap between the opposing conductive layers, the electrolyte layer is sandwiched by a plurality of anode bodies, and external mechanical stress is suppressed by the anode body. Therefore, for example, the electrolyte layer is not damaged even by the pressing of the suction nozzle in the automatic mounting process, and a highly reliable solid electrolytic capacitor can be obtained, and the anode body having the electrolyte layers formed on both surfaces of the cathode body Are arranged, and the capacity can be increased.

In addition, since an anode body made of at least a plate-like strong aluminum or the like is arranged on both upper and lower surfaces, dimensional accuracy is improved. Therefore, the positioning process in the automatic mounting on the printed circuit board is accurate and simplified, and the printing of the polarity display and the like is facilitated.

Furthermore, the cathode electrode is also led out, because the cathode body is sandwiched by a plurality of electrolyte layers via the conductive layer and is drawn out as it is, so there is no connection between the internal lead wire and the external terminal as in the conventional case, and there is poor contact. Inconvenience such as does not occur.

Further, as a manufacturing method thereof, while forming an electrolyte layer and a conductive layer on one surface of the anode body, after bonding a plurality of anode bodies with a cathode body in contact with the conductive layer,
At least the gap between the anode bodies was covered with an insulating layer, and the terminal part and the cathode body previously drawn out of the anode body were bent along the outer surface of the anode body, so that an electrolyte layer was formed on the anode body. After that, by bonding to another anode body, the cathode electrode can be led out through the conductive layer. This eliminates the step of welding the internal lead wire for drawing the cathode onto the electrolyte layer as in the conventional case, thereby simplifying the process and minimizing the damage to the electrolyte layer in the manufacturing process.

Further, the cathode body is sandwiched between the electrolyte layer formed on the anode body and the conductive layer, and is drawn out as it is. Therefore, a solid electrolytic capacitor that can be surface-mounted on a printed circuit board can be manufactured by simply bending the projecting cathode body along the outer surface of the anode body without connecting it to other external connection terminals, etc. can do.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. 3 and 5 are perspective views illustrating a method for manufacturing a solid electrolytic capacitor according to the present invention, FIG. 4 is a conceptual diagram illustrating an electrolyte layer forming process during the process, and FIG. It is a perspective view showing an example. DESCRIPTION OF SYMBOLS 1 ... Anode body, 2 ... Resist layer, 3 ... Electrolyte layer, 4 ... Conductive layer, 5 ... Cathode body, 6 ... Anode terminal, 7 ... Resin layer, 8 ... Exterior resin, 9 ... ... Anode body surface.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01G 9/04 H01G 9/012

Claims (2)

(57) [Claims] 1. A solid electrolyte comprising: an anode body having an oxide film layer, an electrolyte layer and a conductive layer formed on the surface in this order; and a conductive body of the anode body being in contact with both sides of a strip-shaped cathode body. Capacitors. 2. An anode body having an electrolyte layer and a conductive layer formed on one surface thereof and a plurality of anode bodies bonded together with a cathode body in contact with the conductive layer, and at least a gap between the anode bodies is formed by an insulating layer. Wherein the terminal portion and the cathode body previously led out of the anode body are bent along the outer surface of the anode body.