JP3206776B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor, and more particularly to a method for manufacturing 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 formed into chips in response to demands for downsizing electronic devices and increasing the efficiency of mounting on printed circuit boards. Along with this, there is an increasing demand for a chip and a low profile of the electrolytic capacitor. Also, with the diversification of electronic devices, various characteristics are required for chip-type electrolytic capacitors.

[0003] In the solid electrolytic capacitor, in addition to a solid electrolyte composed of a metal oxide semiconductor such as manganese dioxide, a conductive polymer such as tetracyanoquinodimethane (TCNQ), polypyrrole, or polyaniline is applied to the solid electrolytic capacitor. Proposed. It is said that solid electrolytic capacitors using these conductive polymers are higher in conductivity than manganese dioxide or the like, and polypyrrole or the like is particularly excellent in heat resistance, so that it is most suitable for chip formation.

[0004]

The electrolyte layer made of a conductive polymer such as polypyrrole is formed, for example, by 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), and a voltage is applied (electrolytic polymerization) while being immersed in a solution in which pyrrole is dissolved. An electrode lead-out means is provided on the surface of the electrolyte layer, and the outer surface is covered with an exterior resin or the like.

In a solid electrolytic capacitor having such a structure, when a conductive layer is provided on the surface of the anode body for extracting an electrode from the anode body, in order to prevent a short circuit and an increase in leakage current,
A strong electrolyte layer was needed. Therefore, electrolytic polymerization was indispensable as a means for generating an electrolyte layer. However, since the oxide film layer on the anode body surface is an insulator, it is extremely difficult to directly generate an electrolyte layer by electrolytic polymerization. there were. Therefore, a so-called pretreatment by the chemical polymerization as described above is required, and the manufacturing process is complicated.

[0006] In both chemical polymerization and electrolytic polymerization, the anode body is immersed in a pyrrole solution. For this reason, the pyrrole solution crawls up to unnecessary parts, causing problems such as a short circuit accident and an increase in leakage current. For this reason, it is necessary to selectively mask the surface of the anode body or to control the liquid level of the pyrrole solution, which complicates the manufacturing process. In particular, in the case of electrolytic polymerization, it is necessary to strictly control the applied voltage, adjust the distance between the anode body surface and the terminal pin for electrolytic polymerization, and the like, and this is not necessarily suitable for mass production.

Further, the polypyrrole produced in the above-mentioned steps is extremely weak in mechanical strength, and it has been difficult to form an anode body, which is the main body of a chip-type solid electrolytic capacitor. For example, when forming an electrolyte layer on a flat anode body and cutting it to form individual anode bodies,
In this cutting step, the polypyrrole layer was sometimes damaged, and desired electrical characteristics could not be obtained. These difficulties become smaller as product dimensions decrease.
It is increasing more and more in conjunction with the refinement of the processing accuracy of manufacturing equipment.

An object of the present invention is to provide a method for easily manufacturing a highly reliable solid electrolytic capacitor having stable electric characteristics in a fine chip type solid electrolytic capacitor in view of the above-mentioned state. It is in.

[0009]

According to the present invention, there is provided a method of manufacturing a solid electrolytic capacitor, comprising the steps of forming an electrolyte layer made of a conductive polymer on the surface of each of an anode body and a cathode body; Laminating in the electrolyte layer on the surface, including a conductive polymer solution or a suspension of a conductive polymer dispersed in a solvent between the electrolyte layers of the anode body and the cathode body, the anode body and the cathode After laminating the body, the solvent of the conductive polymer solution or suspension is removed.

In the present invention, the anode body is made of a valve metal such as aluminum or tantalum, and may have a plate-like or foil-like shape, but its surface is previously subjected to an etching treatment. In addition, although one anode body may be used, a plurality of anode bodies may be stacked and used when there is room in external dimensions. As the cathode body, iron, copper, nickel or the like may be used in addition to a valve metal such as aluminum. Examples of the electrolyte layer formed on the surfaces of the anode body and the cathode body include polypyrrole and polyaniline. The polymerization method includes chemical polymerization, gas phase polymerization, electrolytic polymerization, and the like, and it is preferable to form the electrolyte layer by using these polymerization methods alone or in combination. Further, examples of the conductive polymer solution interposed between the anode body and the cathode body include polyaniline and soluble polypyrrole. As the suspension, for example, pyrrole is added to P-
It is preferable that an oxidizing agent composed of an aqueous solution of ammonium persulfate is added to a solution of tetraethylammonium toluenesulfonate / acetonitrile, and polypyrrole is dispersed in the solvent by a chemical polymerization reaction.

[0011]

In the method for manufacturing a solid electrolytic capacitor according to the present invention, the electrolyte layers 3 (electrolyte layers 31, 32) made of a conductive polymer are previously formed on the surfaces of the anode body 1 and the cathode body 2.
The anode body 1 and the cathode body 2 are laminated on the electrolyte layer 31 and the electrolyte layer 32, respectively. And
When the anode body 1 and the cathode body 2 are laminated, a suspension 33 (or a conductive polymer solution) in which a conductive polymer is dispersed in a solvent is applied to the surface of the electrolyte layer 31 of the anode body 1 or the cathode body 2. After the anode body 1 and the cathode body 2 are laminated, the solvent of the suspension 33 is removed on the surface of the electrolyte layer 32, or both, by means of application, spraying, dropping, or the like. As a result, a solid electrolyte is generated in the gap between the anode body 1 and the cathode body 2, that is, in the gap between the respective electrolyte layers 31 and 32, forming a layer which may be referred to as a second electrolyte layer 34. And the cathode body 2 are joined.

As a result, it is not necessary to provide an electrode extraction means such as a conductive layer or an internal terminal on the surface of the generated electrolyte layer as in the prior art. By joining the one electrolyte layer 31, the electrode lead-out structure, particularly the electrode lead-out structure on the cathode side, becomes simple.

[0013]

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 an anode body and a cathode body used in an embodiment of the present invention, and FIG. 2 is a perspective view showing an anode body used in the embodiment. 3 to 5 are explanatory views for explaining a manufacturing process of the solid electrolytic capacitor according to the embodiment of the present invention, and FIG. 6 is a partial sectional view showing the solid electrolytic capacitor manufactured according to the embodiment.

The anode body 1 is made of a valve metal such as aluminum and is formed in a flat plate shape as shown in FIG. 1 (A), and a part of its surface is selectively etched and formed by a chemical conversion treatment. An oxide film layer 5 is formed. The chemical conversion treatment is performed by immersing the anode body 1 in a chemical electrolyte for formation while covering a part of the anode body 1 with a resin or the like, and applying a voltage. The generated oxide film layer 5 is made of aluminum oxide in which the surface layer of anode body 1 is oxidized, and becomes a dielectric of anode body 1. The resin and the like used in the chemical conversion treatment and the like are removed after the chemical conversion treatment is performed on the anode body 1.

Further, as shown in FIG. 1B, the cathode body 2 is formed in a flat plate shape similarly to the anode body 1. The cathode body 2 may use a cladding material of aluminum and copper or a solderable metal such as copper or nickel, in addition to a valve metal such as aluminum.

Then, an electrolyte layer 31 made of a conductive polymer is formed on the surface of the oxide film layer 5 of the anode body 1.
In this embodiment, polypyrrole is used as the conductive polymer, and the anode body 1 is immersed in a pyrrole solution containing an oxidizing agent to form a polypyrrole film on the surface by chemical polymerization. In the case where the electrolyte layer 31 is formed into a stronger film, after the chemical polymerization, the anode body 1 may be immersed in a solution in which pyrrole is dissolved while applying a voltage to perform the electrolytic polymerization.

On the other hand, an electrolyte layer 32 made of a conductive polymer is formed on the surface of the cathode body 2 as in the case of the anode body 1. The electrolyte layer 32 formed on the surface of the cathode body 2 may be formed by any of gas phase polymerization, chemical polymerization, electrolytic polymerization, or a combination thereof. In particular, in the case of electrolytic polymerization, since the oxide film layer 5 which is an insulator is not formed on the surface unlike the anode body 1, the pretreatment by chemical polymerization is not required. In the case of gas-phase polymerization or chemical polymerization, an extremely thin film is formed, but the object of the present invention can be achieved.

The anode body 1 and the cathode body 2 thus formed are laminated. At this time, the electrolyte layer 31 of the anode body 1 is
Alternatively, as shown in FIG. 2, a suspension 33 in which a conductive polymer, in this embodiment, polypyrrole is dispersed in a solvent is dropped on the surface of the electrolyte layer 32 of the cathode body 2. The suspension 33 was prepared by adding 0.2 m of pyrrole to an acetonitrile solution.
ol / l and 0.1 mol / l of tetraethylammonium P-toluenesulfonate in a solution of 1.0 m
It is formed by adding an oxidizing agent consisting of an ol / l aqueous solution of ammonium persulfate. Note that these solutions, that is, a pyrrole solution and an aqueous ammonium persulfate solution may be separately dropped on the surface of the electrolyte layer 3 to form the suspension 33 on the electrolyte layer 3.

Then, as shown in FIG. 3, the anode body 1 and the cathode body 2 are overlapped on the electrolyte layer 31 and the electrolyte layer 32, respectively, and left at 100 ° C. for 30 minutes to perform a drying treatment. The solvent of the suspension 33 is removed.
As a result, a second electrolyte layer 34 is generated between the anode body 1 and the cathode body 2, and the second electrolyte layer 34 is formed between the electrolyte layer 31 of the anode body 1 and the cathode body 2. Electrolyte layer 3
2 to form a capacitor element 10. In addition,
In this embodiment, although two cathode bodies 2 are arranged on both surfaces of the anode body 1, a capacitor element provided with a plurality of anode bodies 1 can be formed if necessary.

Next, as shown in FIG. 4, the surface of the capacitor element 10 is covered with a resin layer 8. The resin layer 8
It is made of an insulating synthetic resin such as an epoxy resin, and may be formed by any method such as molding and potting.

Then, the end of the capacitor element 10 is cut on the cut surfaces X ₁ and X ₂ using a means such as a slicer. At this time, together with the resin layer 8 of the capacitor element 10, the ends of the anode body 1 and the cathode body 2 are cut, and as shown in FIG. An exposed surface of the body 2 is provided. Then, the anode terminal 6 and the cathode terminal 7 for external connection are welded to the exposed surface.

Further, as shown in FIG. 6, on the surface of the capacitor element 9 to which the anode terminal 6 and the cathode terminal 7 are welded,
A solid electrolytic capacitor is obtained by coating an exterior resin 9 made of an epoxy resin or the like, and bending end portions of the anode terminal 6 and the cathode terminal 7 protruding from the bottom surface of the exterior resin 9 along the bottom surface of the exterior resin 9.

In this embodiment, an electrolyte layer 31 and an electrolyte layer 32 are formed on the surfaces of the anode body 1 and the cathode body 2, respectively. Therefore, it is not necessary to sequentially form an oxide film layer, an electrolyte layer, a conductive layer, and the like on the anode body, and by overlapping the anode body 1 and the cathode body 2, the electrodes of both electrodes can be drawn out. Therefore, the manufacturing process is simplified, and the lead-out structure of the electrode is simplified, and damage to the electrolyte layer 3 due to stress in the manufacturing process is reduced.

The joining of the anode body 1 and the cathode body 2 is as follows.
The solvent of the suspension 33 dropped to one of the electrolyte layers 3 is removed after the anode body 1 and the cathode body 2 are overlapped,
This is performed by forming a second electrolyte layer 34 between the anode body 1 and the cathode body 2. Therefore, in bonding the anode body 1 and the cathode body 2, for example, a conductive adhesive or the like is not used, and deterioration of electrical characteristics due to unstable behavior at the interface of the adhesive is eliminated. In particular, in this embodiment, polypyrrole is used for both the electrolyte layer 3 and the second electrolyte layer 34, and the electrical adhesion is also improved.

Further, after the anode body 1 and the cathode body 2 are laminated, the surface thereof is covered with a resin layer 8, and the end face of the resin layer 8 is cut together with the anode body 1 and the cathode body 2. The anode terminal 6 and the cathode terminal 7 are welded to the exposed surfaces of the anode body 1 and the cathode body 2 formed as a result. As described above, the anode body 1 and the cathode body 2 are joined by the second electrolyte layer 34 from which the solvent of the suspension 33 has been removed, but the joining strength is not always strong. However, the resin layer 8 covering the surfaces of the anode body 1 and the cathode body 2 complements the bonding strength. Further, it is not necessary to directly attach the anode terminal 6 and the cathode terminal 7 to the anode body 1 and the cathode body 2, respectively, and the stress in the manufacturing process is reduced.

In this embodiment, the anode terminal 6 and the cathode terminal 7, which are external terminals, are welded to the exposed surfaces of the anode body 1 and the cathode body 2 formed by cutting the resin layer 8. A drawer structure may be used. For example, when iron, copper, or the like is used as the cathode body 2, it may be pulled out to the outside and used as an external terminal, or the external terminal may be welded and then coated with the exterior resin 9.

[0027]

As described above, the present invention provides a method for manufacturing a solid electrolytic capacitor, comprising the steps of forming an electrolyte layer made of a conductive polymer on the surface of each of an anode body and a cathode body; Laminating in the electrolyte layer on the surface, including a conductive polymer solution or a suspension of a conductive polymer dispersed in a solvent between the electrolyte layers of the anode body and the cathode body, the anode body and the cathode After laminating the body, it is characterized by removing the solvent of the conductive polymer solution or suspension, so that a layer also called a second electrolyte layer is formed between the anode body and the cathode body, This second electrolyte layer joins the anode body and the cathode body. Therefore, the step of joining the anode body and the cathode body is simplified, and since the second electrolyte layer having the same quality as the electrolyte layer is used as the joining means, the electrical adhesion is improved and the stability is improved. The obtained electrical characteristics can be obtained.

In joining the anode body and the cathode body,
Separate electrolyte layers are previously formed on the anode body and the cathode body, respectively. And since this is combined with the second electrolyte layer, the structure for extracting the electrodes of both electrodes is simplified,
As in the prior art, the stress when the electrode lead-out means is provided on the anode body or the like is reduced, and damage to a conductive polymer such as polypyrrole, which is fragile in mechanical strength, can be prevented. Therefore, desired electrical characteristics can be easily obtained, and particularly, leakage current characteristics can be improved.

Further, since the electrolyte layers are formed on both the anode body and the cathode body, particularly when the anode body is manufactured, it is possible to sequentially form the electrolyte layer and the conductive layer on the oxide film layer as in the conventional case. This eliminates the necessity of masking portions other than desired portions in the step of forming each layer. Further, the electrolyte layers formed on each surface of the anode body and the cathode body may be formed by, for example, only chemical polymerization, so that the polymerization process is greatly simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a conceptual structure of an anode body and a cathode body used in an embodiment of the present invention.

FIG. 2 is a perspective view showing an anode body used in Examples.

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

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

FIG. 5 is an explanatory view illustrating a manufacturing process of the solid electrolytic capacitor according to the embodiment of the present invention.

FIG. 6 is a partial cross-sectional view showing a solid electrolytic capacitor manufactured according to an example.

[Explanation of symbols]

 Reference Signs List 1 anode body 2 cathode body 3 electrolyte layer 31 electrolyte layer (anode side) 32 electrolyte layer (cathode side) 33 suspension 34 second electrolyte layer 5 oxide layer 6 anode terminal 7 cathode terminal 8 resin layer 9 exterior resin 10 Capacitor element

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁷ Identification code FI H01G 9/05 M

Claims (1)

(57) [Claims] An anode body and a cathode include a step of forming an electrolyte layer made of a conductive polymer on a surface of each of an anode body and a cathode body, and a step of laminating the anode body and the cathode body on the electrolyte layer on the surface thereof. Between the electrolyte layers of the body, a conductive polymer solution or a suspension in which a conductive polymer is dispersed in a solvent is interposed, and after the anode body and the cathode body are laminated, the conductive polymer solution or the suspension is formed. A method for producing a solid electrolytic capacitor for removing a solvent.