JP3307446B2 - 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 solid electrolytic capacitor and a method of manufacturing the same, and more particularly to a solid electrolytic capacitor using a solid electrolyte made of polypyrrole, which is an organic conductive compound.

[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.

In a solid electrolytic capacitor, a solid electrolyte composed of an organic conductive compound such as tetracyanoquinodimethane (TCNQ), polypyrrole, or polyaniline is used in addition to a solid electrolyte composed of a metal oxide semiconductor such as manganese dioxide. The one applied to is proposed. Solid electrolytic capacitors using these organic conductive compounds have higher conductivity than manganese dioxide and the like,
Significant improvement in electrical characteristics, particularly ESR characteristics, can be expected.

In order to form an electrolyte layer made of an organic conductive compound such as polypyrrole, for example, an anode body is immersed in a pyrrole solution containing an oxidizing agent to form a pyrrole thin film on the surface of the anode body (chemical polymerization). ), And then applying a voltage (electrolytic polymerization) while immersing in a solution in which pyrrole is dissolved has been proposed.

[0005] Such a proposal has a background that a strong electrolyte layer cannot be obtained with an electrolyte layer formed only by chemical polymerization. As a result, it becomes very difficult to provide a means for extracting an electrode such as a conductive paste formed on the surface of the electrolyte layer, and the application of the conductive paste may damage the electrolyte layer, thereby causing a short circuit accident or a function of extracting an electrode of the electrolyte layer. Is not sufficient, a desired capacitance may not be obtained.

On the other hand, although a strong electrolyte layer can be obtained by electrolytic polymerization, it is necessary to apply a voltage to the anode body. However, a dielectric (oxide film layer), which is an insulator, is formed on the surface of the anode body, and it is difficult to directly form an electrolyte layer on the surface of the anode body by electrolytic polymerization. Therefore, as a pretreatment, an electrolyte layer is first formed by chemical polymerization, and a strong electrolyte layer is obtained by performing electrolytic polymerization using the electrolyte layer as an electrode.

[0007]

However, in electrolytic polymerization,
Since a voltage is applied in a pyrrole solution containing an oxidizing agent, there is an inconvenience that it is difficult to reuse the pyrrole solution, and a voltage is applied to each capacitor element.
In addition, it is difficult to say that it is necessary to strictly manage the liquid surface in order to prevent the pyrrole solution from creeping up to the terminal portion of the capacitor element.

Therefore, it is conceivable to form an electrolyte layer made of polypyrrole only by chemical polymerization. In this case, as described above, it is necessary to consider the electrode extraction means on the cathode side, and it is necessary to ensure not only the adhesion between the electrolyte layer made of polypyrrole and the anode body but also the adhesion to the cathode body. That is, if a pyrrole solution and an oxidizing agent solution are applied and dropped onto the surface of the anode body, an electrolyte layer made of polypyrrole is generated, and its adhesion is ensured, but the cathode body is further arranged on this electrolyte layer. Also, almost no adhesion between the electrolyte layer and the cathode body can be obtained. For this purpose, a conductive layer such as a conductive paste has conventionally been provided. However, it is difficult to form a conductive layer with a fragile electrolyte layer generated only by chemical polymerization.

It is also conceivable to arrange the cathode body during the chemical polymerization reaction, but since the chemical polymerization reaction occurs rapidly, it is difficult to adjust the timing thereof, which is not suitable for mass production. In addition, it is inevitable that a pyrrole solution (polypyrrole during generation) or the like which causes a short circuit is protruded, and it is necessary to carefully adjust the dripping amounts of the pyrrole solution and the oxidizing agent solution.

An object of the present invention is to realize a highly reliable solid electrolytic capacitor having stable electric characteristics in a solid electrolytic capacitor using polypyrrole in view of the above-described state.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing a solid electrolytic capacitor in which an anode body and a cathode body having an oxide film layer and an electrolyte layer made of polypyrrole formed on the surface thereof are opposed to each other. The method is characterized in that the solution is applied only to one of the surfaces of the anode body and the cathode body, and then the anode body and the cathode body are joined.

Further, as another technical means, in a method for manufacturing a solid electrolytic capacitor in which an anode body and a cathode body are opposed to each other with a separator interposed therebetween, a pyrrole solution and an oxidizing solution are mixed with the surface of the separator and the surface of the anode body, respectively. After impregnating and coating only one of the above, the anode body and the cathode body are joined via a separator.

[Action]

In the present invention, the electrolyte layer 4 comprises the anode body 1
Of the pyrrole solution 5 applied to the surface of the cathode body 2 and the oxidant solution 6 applied to the surface of the cathode body 2, or the oxidant solution 6 on the surface of the anode body 1 and the pyrrole solution 5 on the surface of the cathode body 2 Produced by chemical polymerization. Then, in the manufacturing process, a chemical polymerization reaction occurs almost simultaneously with the joining of the anode body 1 and the cathode body 2, and thereafter, there is no need to drop and apply a pyrrole solution or the like.

Since the pyrrole solution 5 or the oxidizing agent solution 6 is interposed on the surfaces of the anode body 1 and the cathode body 2, respectively, an electrolyte layer made of polypyrrole is formed on both surfaces of the anode body 1 and the cathode body 2 by a chemical polymerization reaction. 4 are uniformly adhered, and it is possible to reliably take out the electrode particularly on the cathode side.

As another technical means, a pyrrole solution 5 is dropped on the surface of the anode body 1 and a separator 7 is formed.
Is impregnated with the oxidizing agent solution 6 or the oxidizing agent solution 6 is dropped on the surface of the anode body 1, and the pyrrole solution 5 is impregnated into the separator 7, and the separator 7 is laminated on the surface of the anode body 1 together with the cathode body 2. Similarly, the electrolyte layer 4 made of polypyrrole adheres to the surfaces of the anode body 1 and the cathode body 2. When the separator 7 is used as described above, the pyrrole solution 5
Alternatively, the drop amount of the oxidizing agent solution 6 is increased, and the electrolyte layer 4 having a more sufficient thickness is obtained, and the separation distance between the anode body 1 and the cathode body 2 is kept constant, that is, the electrolyte layer 4
It is easy to maintain a uniform thickness. In addition, as the separator 7, glass paper can be used in addition to manila paper.

[0016]

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

The anode body 1 is made of a plate-shaped valve metal such as aluminum or tantalum. As shown in FIG. 2, the surface of the anode body 1 is subjected to an etching process in advance to increase the surface area, and a chemical conversion process is performed. Is applied to form oxide film layer 3. The oxide film layer 3 is formed by oxidizing the surface of the anode body 1 and serves as a dielectric of the capacitor. The cathode body 2 is made of a plate-like valve metal such as aluminum or tantalum, like the anode body 1, and has no oxide film layer formed on its surface, but is etched to increase the surface area. ing.

As shown in FIGS. 1 (a) and 1 (b), a predetermined amount of a pyrrole solution 5 or an oxidizing agent solution 6 is dropped on the surfaces of the anode body 1 and the cathode body 2, respectively. The pyrrole solution 5 may be dropped on any surface of the anode body 1 and the cathode body 2, but in the chemical polymerization reaction between the pyrrole solution 5 and the oxidant solution 6, the pyrrole solution 5 goes from the pyrrole solution 5 side to the oxidant solution 6 side. Since polypyrrole is generated in the direction, the pyrrole solution 5 is desirably placed on the surface of the cathode body 2.
Is dropped, and an oxidizing agent solution 6 is preferably formed on the surface of the anode body 1.

The oxidizing agent solution 6 contains 1.5 mol / l
Of ammonium persulfate and 0.5 mol / l of tetraethylammonium P-toluenesulfonate. The means for coating the surfaces of the anode body 1 and the cathode body 2 is not limited. As shown in the embodiment, it may be dropped, or a means such as screen printing may be used.

Then, as shown in FIG. 2, the anode body 1 and the cathode body 2 to which the pyrrole solution 5 and the oxidizing agent solution 6 have been respectively dropped are bonded. At this time, the pyrrole solution 5 and the oxidizing agent solution 6 come into contact with each other to cause a chemical polymerization reaction, and the anode body 1
Electrolyte layer 4 made of polypyrrole in the gap between
Is generated to constitute the capacitor element 10.

As shown in FIG. 2, the capacitor element 10 thus constructed has an oxide film layer 3 and an electrolyte layer 4 formed sequentially on the surface of the anode body 1 as shown in FIG. The cathode body 2 is disposed in close contact with the layer 4.

The capacitor element 10 is, for example, attached to an anode body 1 and a cathode body 2 of the capacitor element 10 with external connection terminals, and housed in an outer frame having a housing space for housing the capacitor element 10. The opening is sealed with a sealing resin such as an epoxy resin to obtain a solid electrolytic capacitor. Alternatively, the outer surface of capacitor element 10 may be covered with a mold resin or the like.

In this embodiment, the oxidant solution 6
And a pyrrole solution 5 on the surface of the cathode body 2.
Is applied, the anode body 1 and the cathode body 2 are bonded together, and polypyrrole is generated by a chemical polymerization reaction in a gap between the anode body 1 and the cathode body 2, and this is used as an electrolyte layer 4. For this reason, since a means such as immersing the bonded anode body 1 and cathode body 2 in a mixed solution of a pyrrole solution and an oxidizing agent solution is not used as in the related art, a desired portion, that is, the anode body 1 is not used. The electrolyte layer 4 can be selectively formed only on the bonding surface between the anode and the cathode body 2 without using a means such as masking.

Next, another embodiment of the present invention shown in FIG. 3 will be described. In this embodiment, the anode body 1 and the cathode body 2 are joined via a separator 7, and a pyrrole solution 5 or an oxidant solution 6 is dropped on the surface of the anode body 1 and the separator 7, respectively. Here, the oxidizing agent solution 6 was dropped on the surface of the anode body 1 and the pyrrole solution 5 was impregnated in the separator 7 in the same manner as in the previous example. In addition,
The separator 7 may be impregnated with the oxidant solution 6, but in this case, it is desirable to use glass paper as the separator 7 in order to suppress a decrease in the oxidizing ability of the oxidant solution 6. This is because, in the case of a separator made of ordinary manila paper or the like, an oxidation reaction may occur with the oxidizing agent solution 6 and the oxidizing ability of the oxidizing agent solution 6 may be reduced.

Then, these anode body 1 and cathode body 2 are
As shown in FIG. 3, after joining via a separator 7, a capacitor element 11 is formed, and after connecting an electrode lead-out means, an exterior structure such as a mold resin is provided.

In this embodiment, the separator 7 is impregnated with the pyrrole solution 5. Then, the cathode body 2 and the anode body 1 coated with the oxidant solution 6 on the surface thereof through the separator 7.
And an electrolyte layer 4 made of polypyrrole is adhered to the surfaces of the anode body 1 and the cathode body 2 by a chemical polymerization reaction occurring at the time of the bonding. For this reason, it is possible to impregnate the separator 7 with a larger amount of the pyrrole solution 5 than in the previous example, so that the electrolyte layer 4 having a sufficient thickness can be obtained.

The pyrrole solution 5 and the oxidizing agent solution 6
When the anode body 1 and the cathode body 2 are joined, they are both held by the separator 7, so that the protrusion from the capacitor element 11 can be more completely prevented. Further, the distance between the anode body 1 and the cathode body 2 is also constant by the separator 7, so that a uniform electrolyte layer 4 can be generated, and the electrolyte layer 4 becomes strong against external stress.

[0028]

As described above, the present invention relates to a method for manufacturing a solid electrolytic capacitor in which an anode body and a cathode body having an oxide film layer and an electrolyte layer made of polypyrrole formed on the surface thereof are opposed to each other. The solution is applied to only one of the surfaces of the anode body and the cathode body, respectively, and then the anode body and the cathode body are joined together. A selective electrolyte layer can be easily provided without masking with a resist or the like.

Further, a pyrrole solution and an oxidizing agent solution are applied to either the surface of the anode body or the surface of the cathode body, respectively, and joined to each other to cause a chemical polymerization reaction, whereby the electrolyte layer and the cathode body are separated. Because of the close contact, there is no need to provide a cathode extraction means such as a conductive paste on the already generated electrolyte layer, and the overall element structure is simplified, and a solid electrolytic capacitor can be manufactured without the need for electrolytic polymerization. it can.

Since no electrolytic polymerization step is required, the production process is simplified, and no special production equipment is required. Further, the oxide film layer is not damaged by voltage application in the electrolytic polymerization step, and in particular, the leakage current characteristics can be stably maintained for a long time.

According to the present invention, as another technical means, in a method for manufacturing a solid electrolytic capacitor in which an anode body and a cathode body are opposed to each other with a separator interposed therebetween, a pyrrole solution and an oxidizing agent solution are added to the separator and the anode, respectively. After impregnating only one of the surface of the body, after applying, it is characterized by joining the anode body and the cathode body via a separator, the amount of dripping of the pyrrole solution or the oxidizing agent solution increases, An electrolyte layer having a sufficient thickness can be obtained, and it is easy to keep the distance between the anode body and the cathode body constant, that is, to keep the thickness of the electrolyte layer uniform.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a manufacturing process according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a conceptual structure of a solid electrolytic capacitor according to an embodiment.

FIG. 3 is a sectional view showing a conceptual structure of a solid electrolytic capacitor according to a second embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 anode body 2 cathode body 3 oxide film layer 4 electrolyte layer 5 pyrrole solution 6 oxidizing agent solution 7 separator 10, 11 capacitor element

Claims (2)

(57) [Claims] 1. A solid electrolytic capacitor in which an anode body and a cathode body each having an oxide film layer and an electrolyte layer made of polypyrrole formed on the surface thereof are opposed to each other. A method of manufacturing a solid electrolytic capacitor in which an anode body and a cathode body are joined after being applied to only one of the surfaces. 2. In a solid electrolytic capacitor in which an anode body and a cathode body are opposed to each other with a separator interposed therebetween, a pyrrole solution and an oxidizing agent solution are impregnated and applied to only one of the separator and the surface of the anode body, respectively. After that, a method for manufacturing a solid electrolytic capacitor in which an anode body and a cathode body are joined via a separator.