JP3416061B2 - Solid electrolytic capacitor and method of manufacturing the same - 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 manufacturing method thereof, and more particularly to a solid electrolytic capacitor having a solid electrolyte layer made of a conductive polymer and a manufacturing method thereof.

[0002]

2. Description of the Related Art Usually, a solid electrolytic capacitor has a structure in which an anode conductor, a dielectric layer, a solid electrolyte layer, and a cathode conductor are arranged in the above order.

Conventional solid electrolytic capacitors utilize manganese dioxide as a solid electrolyte layer. In the manufacturing method, a metal having a valve action such as tantalum or aluminum is used as an anode conductor, and the metal is anodized in an electrolyte solution to form an oxide film layer (dielectric layer) on the surface thereof. Next, the anode conductor having the oxide film layer is immersed in a manganese nitrate solution and fired to form a solid electrolyte layer made of manganese dioxide on the oxide film surface. Finally, a solid electrolytic capacitor is completed by forming a cathode conductor on the solid electrolyte layer.

In recent years, in electronic equipment in which a solid electrolytic capacitor is used, the frequency of integrated circuits is increasing and the current is increasing significantly. Along with this, the equivalent series resistance is low, the capacitance is large,
Moreover, a solid electrolytic capacitor with low loss is required.

It is considered that the factors that determine the equivalent series resistance are the resistances of the solid electrolyte layer, the negative and anode conductors, the negative and anode conductor terminals, and the dielectric film, which are conductive paths for the charge and discharge current of the capacitor. Conventionally, the main factor was considered to be the solid electrolyte.

In view of the above factors, manganese dioxide used as a solid electrolyte in the prior art has a conductivity of about 0.1 to 1 S / cm, but a conductive polymer material having a conductivity higher than this has been found. Was done. When a solid electrolyte layer is formed of a conductive polymer such as polypyrrole, the electrolyte has a high conductivity of about 100 S / cm, and also has stability over time and resistance to heat and humidity, so a tantalum solid with good high frequency characteristics is obtained. An electrolytic capacitor can be obtained (see JP-A-2-130906). Cyclic organic compound polymers such as aniline and furan are known as other conductive polymer materials.

Further, it is also known to form an intermediate layer made of a conductive polymer between the cathode conductor and the solid electrolyte layer. However, most of the conductive polymers constituting the intermediate layer have been obtained by chemically or chemically polymerizing the same monomer used in the solid electrolyte layer, and the conductive polymer materials are not different. The intermediate layer may not be formed.

Since the oxide film of the anode conductor is insulative and it is difficult to use the electrolytic polymerization method to form the conductive polymer on the surface of the oxide film, it is necessary to use the chemical polymerization method. Specifically, the chemical polymerization method involves immersing a sintered body, which is an anode conductor having an oxide film, in a mixed solution obtained by mixing a monomer solution and an oxidant solution, and then forming an oxide film on the surface of the micropores of the sintered body. A polymer layer is formed on the surface. Alternatively, a porous sintered body having an oxide film formed thereon may be impregnated with a monomer solution and then immersed in an oxidizing agent solution to form a polymer layer on the oxide film on the surface of the micropores of the sintered body. .

Further, the polymer layer formed by the chemical polymerization method can be used as an electrode for electrolysis, which plays a role of an anode during electrolytic polymerization, by ensuring a sufficient film thickness. Specifically, a sintered body provided with a polymer film is immersed in an electrolytic solution containing a monomer, and an electrode is bonded to the polymer film to form an anode, while a cathode plate is placed in the solution to carry out electrolytic polymerization. A polymer film is laminated and grown by this to form an intermediate layer made of a conductive polymer on the solid electrolyte layer.

Subsequently, a suspension coating containing carbon particles is applied to the surface of the sintered body formed up to the intermediate layer, the suspension coating is dried and solidified to form a carbon layer, and silver is further contained on the carbon layer. The suspension paint is applied to complete a cathode conductor composed of a carbon layer and a silver layer. Carbon particles are other carbon particles,
It is bonded to the intermediate layer and the silver layer to improve conduction inside the capacitor.

[0011]

However, the polymer formed by the electrolytic polymerization method has higher conductivity than that obtained by the chemical polymerization method, but is characterized by a strong and smooth film-like product. However, there is a problem that the polymer has poor adhesion to the cathode conductor and has a high equivalent series resistance.

Further, even if a conductive polymer having a high conductivity is used for the solid electrolyte, the equivalent series resistance of the solid electrolytic capacitor does not fall below a certain value. Upon detailed examination, it was found that the equivalent series resistance is much larger than the total value of the resistance of each member in the conductive path of the charging / discharging current of the capacitor.

The present invention has been made in view of the above problems of the prior art, and provides a solid electrolytic capacitor having a low equivalent series resistance and a low loss, and a method for manufacturing the same.

[0014]

When the above-mentioned problems are examined in more detail, the main cause of the equivalent series resistance is that the carbon particles 1 protruding from the surface of the cathode conductor 5 as shown in FIG.
It was predicted that this was caused by the contact resistance between 1 and the solid electrolyte layer 3. Further, when a solid electrolytic capacitor including an intermediate layer was examined, it was predicted that the contact resistance depending on the contact between the carbon particles protruding from the surface of the cathode conductor and the intermediate layer would affect the characteristics of the solid electrolytic capacitor. .

In the solid electrolytic capacitor according to the present invention, the conductive polymer intermediate layer interposed between the solid electrolyte layer and the cathode conductor is made of a soft material to bring the intermediate layer into close contact with the carbon particles and The contact area between the intermediate layer and the intermediate layer is increased, the contact resistance is reduced, and the series equivalent resistance is reduced.

Further, in the solid electrolytic capacitor, it is preferable that the solid electrolyte layer is formed of a conductive polymer, and the hardness of the conductive polymer intermediate layer is smaller than the hardness of the solid electrolyte layer.

Further, in the above solid electrolytic capacitor, it is preferable that the conductive polymer intermediate layer is provided with a protrusion made of conductive particles on the cathode conductor side, and the protrusion is closely attached to the carbon particle group.

The method for producing a solid electrolytic capacitor according to the present invention comprises: an anode conductor; a dielectric layer formed on the surface of the anode conductor; a solid electrolyte layer formed on the surface of the dielectric layer; In the method for producing a solid electrolytic capacitor having a conductive polymer intermediate layer formed on the surface of an electrolyte layer and a cathode conductor formed on the surface of the conductive polymer intermediate layer, the anode made of a metal having a valve action. On the conductor
Using the solid electrolyte layer forming step of forming the solid electrolyte layer via the dielectric layer, a monomer solution containing a monomer and an oxidizing agent solution containing an oxidant, the solid of the monomer by a chemical polymerization method. The conductive polymer intermediate layer made of a polymer having a hardness smaller than that of the electrolyte layer,
Conductive polymer intermediate layer forming step to be formed on the surface of the solid electrolyte layer, the cathode conductor is formed on the surface of the conductive polymer intermediate layer, the carbon particle group contained in the cathode conductor to the conductive polymer intermediate layer And a step of forming a cathode conductor in close contact with each other.

Specifically, in the method for producing the solid electrolytic capacitor described above, in the step of forming the conductive polymer intermediate layer,
The conductive polymer having a protrusion on the cathode conductor side is prepared by mixing the monomer solution and the oxidant solution, and using a mixed solution containing carbon particles or polymer particles of the monomer as conductive particles. Forming an intermediate layer,
In the step of forming the cathode conductor, it is preferable that the protrusion is closely attached to the carbon particle group.

Further, in the method for producing a solid electrolytic capacitor described above, in the step of forming the conductive polymer intermediate layer, the monomer solution and the oxidant solution are mixed, and a part of the monomer is oxidatively polymerized to form the monomer. It is also possible to generate a polymer, prepare a mixed solution in which the polymer and the monomer are mixed, and use the mixed solution to form the conductive polymer intermediate layer having the protrusion.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the solid electrolytic capacitor of the present invention will be described below. As shown in Figure 1,
The capacitor element 16 according to the present invention has a structure in which the anode conductor 1 and the cathode conductor 5 face each other with the dielectric layer 2, the solid electrolyte layer 3 and the conductive polymer intermediate layer 4 interposed therebetween. Specifically, the dielectric layer 2 is formed on the surface of the anode conductor 1, the solid electrolyte layer 3 is formed on the surface of the dielectric layer 2, and the conductive polymer intermediate layer 4 is composed of the solid electrolyte layer 3 and the cathode conductor 5. It is formed so as to be interposed therebetween.

The anode conductor 1 is formed of a sintered pellet made of a valve metal or fine particles thereof.
Specifically, tantalum, aluminum, titanium, niobium, zirconium, zinc or the like is used. Furthermore, in order to increase the capacitance, a metal foil subjected to surface expansion treatment by etching or the like is used for the anode conductor 1. The dielectric layer 2 is an oxide film obtained by oxidizing the surface of the cathode conductor 1, and is also formed in the pores of the sintered pellet.

The solid electrolyte layer 3 and the conductive polymer intermediate layer 4 are both formed of a conductive polymer, and the conductive polymer material forming the conductive polymer intermediate layer 4 forms the solid electrolyte layer 3. Softer than the conductive polymer material. Specifically, the solid electrolytic layer 3 is formed of polypyrrole or the like, the conductive polymer intermediate layer 4 is 3,
It is formed from a polymer of 4-ethylenedioxythiophene. Since the dielectric layer 2 is insulative and it is difficult to provide a current supply electrode on the surface of the dielectric 2 to carry out electrolytic polymerization, the solid electrolyte layer 3 is preferably formed by a chemical polymerization method.

In the present specification, soft means having at least one of the characteristic that elastic deformation is easy (flexibility) and the characteristic that plastic deformation is easy (plasticity).

The cathode conductor 5 has a two-layer structure including a carbon layer 9 and a silver paint layer 10. further,
The carbon layer 9 contains carbon particles that are conductive particles, and the carbon particles project toward the conductive polymer intermediate layer 4 side.

The cathode conductor 5 and the solid electrolyte layer 3 are electrically connected to each other through the conductive polymer intermediate layer 4. Figure 2
As shown in, the conductive polymer intermediate layer 4 is formed so as to contact the surface of the solid electrolyte layer 3, and the protrusions of the cathode conductor 5, that is, the carbon particles 11 are adhered to the conductive polymer intermediate layer 4. There is.

In the present invention, the conductive polymer intermediate layer 4
Since the polymer forming the is soft, the carbon particles 11 contained in the cathode conductor 5 adhere to the conductive polymer intermediate layer 4 as shown in FIG.
It is possible to increase the number of joint surfaces between the carbon particles 11 and the carbon particles 11. Therefore, the resistance value depending on the contact between the conductive polymer 4 and the carbon particles 11 can be reduced, and the equivalent series resistance of the solid electrolytic capacitor element 16 can be reduced.

Further, as shown in FIG. 4, a cathode lead terminal 13 and an anode lead terminal 14 are provided on the capacitor element 16.
Is attached and is covered with epoxy resin 15 to complete the electrolytic capacitor 17 according to the present invention. Cathode lead terminal 13
Are attached to the capacitor element 16 by a conductive adhesive 12.

Next, a modification of the above embodiment will be described. In the solid electrolytic capacitor element according to this modification, as shown in FIG. 3, conductive particles 8 are contained in the conductive polymer intermediate layer 4, and a protrusion is provided on the cathode conductor 5 side of the conductive polymer intermediate layer 4. It is a thing. Conductive particles 8
Is softer than the conductive polymer material forming the solid electrolyte layer 3, that is, has a greater flexibility or plasticity. Specifically, carbon particles, polymer particles of 3,4-ethylenedioxythiophene, and the like are used.

As shown in FIG. 3, the protrusions of the conductive polymer intermediate layer 4 are brought into close contact with the surfaces of the carbon particles 11 contained in the cathode conductor 5, whereby the conductive polymer intermediate layer 4 is formed.
To increase the contact surface between the conductive polymer intermediate layer 4 and the cathode conductor 5 depending on the contact between the carbon particles 11 to reduce the equivalent series resistance of the solid electrolytic capacitor element. You can

It has been found that the flexibility or plasticity of the above-mentioned conductive material can be evaluated by measuring the hardness of the material. The hardness of the material was measured as follows. The material hardness is measured by the Barcol hardness method in which an intruder is pressed against the sample surface.

First, a film-like conductive polymer compound is formed on the surface of a glass substrate by a chemical polymerization method using various monomers and derivatives thereof, followed by washing and drying with an organic solvent, and a micro hardness tester (Shimadzu). The hardness of the conductive polymer compound film was measured using HMV2000). Next, the same measurement was performed on the above-mentioned monomer and its derivative using various electron-withdrawing aromatic compounds as dopants. Table 1 shows the hardness of each conductive polymer compound and the equivalent series resistance when a solid electrolytic capacitor is manufactured with each material.

[0033]

[Table 1]

As shown in Table 1 above, the hardness of the polymer of 3,4-ethylenedioxythiophene used as the conductive polymer intermediate layer of the solid electrolytic capacitor of the present invention is the same as that of the polypyrrole forming the solid electrolyte layer. It is smaller than hardness and also has an equivalent series resistance smaller than that of polypyrrole.

As Example 1, the solid electrolytic capacitor of the above embodiment was manufactured. Specifically, the anode conductor is made of tantalum metal powder, the solid electrolytic layer is made of polypyrrole, and the conductive polymer intermediate layer is made of a polymer of 3,4-ethylenedioxythiophene to manufacture a solid electrolytic capacitor. did.

The method of manufacturing the solid electrolytic capacitor of Example 1 will be described below with reference to FIG. First, fine powder of tantalum metal with valve action is sintered to 1.4 mm x
Anode conductor 1 made of sintered pellets having a tantalum wire lead for drawing out the anode was manufactured by molding into 3.0 mm × 3.8 mm. Next, the anode conductor 1 is formed with a phosphoric acid solution at about 30 V to form a film of tantalum oxide on the surface of the anode conductor 1, then washed and dried to obtain the anode conductor 1.
A dielectric layer 2 made of a tantalum oxide film was formed on the surface of the.

On the other hand, 10 vo of isopropyl alcohol
Pyrrole as a monomer in an aqueous solution containing 1% of 0.
A monomer solution was prepared by dissolving 1 mol / l. Also, 10 vol% isopropyl alcohol 10 vol
% Iron (III) sulfate as an oxidizing agent in an aqueous solution containing 0.1%
An oxidant solution was prepared by dissolving mol / l and Na salt of alkylnaphthalenesulfonate ion of 0.05 mol / l.

Then, the sintered pellets having the dielectric layer 2 are dipped in the monomer solution and then in the oxidant solution to form a polypyrrole layer, which is a polymer of pyrrole, on the dielectric layer 2. And subsequently the sintered pellets were washed and dried. While repeating the polypyrrole layer forming step 20 times, the sintering pellets are re-formed with a phosphoric acid solution having a concentration of about 0.1% at a formation voltage of about 20V at appropriate times.
The dielectric layer 2 was repaired. Next, about 90
It was washed in pure water at 0 ° C., the ambient temperature was set to about 120 ° C., and the sintered pellets were dried to form the solid electrolyte layer 3 made of polypyrrole on the dielectric layer 2.

On the other hand, 3,4-ethylenedioxythiophene (hereinafter referred to as EDT) which is a monomer and iron (III) p-toluenesulfonate which is an oxidizing agent are mixed in an n-butanol solution to prepare EDT. The polymerization liquid was prepared so that the concentration of 1 mol / l and the concentration of iron (III) p-toluenesulfonate were 1 mol / l.

Further, after the sintered pellets were immersed in the above polymer liquid for about 3 minutes, the ambient temperature was gradually raised from room temperature to 160 ° C. to evaporate the solvent on the surface of the sintered pellets, E
Oxidative polymerization of DT was carried out to form a polymer of EDT.

A monomer solution containing EDT and iron (III) p-toluenesulfonate as an oxidant 1 mol / l
An oxidant solution containing and was separately prepared, and the sintered body pellet was impregnated with the monomer solution, and then immersed in the oxidant solution to accelerate the oxidative polymerization of EDT on the surface of the sintered body pellet. Good.

After the EDT polymerization process as described above is repeated 2 to 5 times, the sintered pellets are washed with isopropyl alcohol and fired at a formation voltage of about 20 V with an aqueous solution of isopropyl alcohol containing 0.1% phosphoric acid. Body pellets were reformed. After re-formation, the sintered pellets are washed in pure water at 40 to 90 ° C and the ambient temperature is room temperature to 120 ° C.
Then, the conductive polymer intermediate layer 4 made of an EDT polymer was formed on the solid electrolyte layer 3.

Next, the sintered pellets are dipped in an aqueous suspension liquid containing carbon fine particles to apply the suspension liquid to the conductive polymer intermediate layer 4, and then about 13
The suspension liquid was dried and solidified by standing at 0 ° C. for about 2 hours to form a carbon layer 9 on the conductive polymer intermediate layer 4. Subsequently, the sintered pellets are immersed in a silver paint solution and left at room temperature for 1 hour, and then the silver paint solution is dried and solidified at about 145 ° C. for 1 hour to form a silver paint layer 10 on the carbon layer 9. Was formed to complete the cathode conductor 5 including the carbon layer 9 and the silver paint layer 10. In this way, the solid electrolytic capacitor element 16 was manufactured.

The conductive polymer intermediate layer 4 made of the EDT polymer thus formed is, as shown in FIG.
Since it is in close contact with the surface of the carbon particles 11 of the cathode conductor 5, the resistance value depending on the contact between the conductive polymer intermediate layer 4 and the carbon particles 11 is reduced, and the equivalent series resistance of the solid electrolytic capacitor element is reduced. You can

Next, while the cathode conductor 5 of the solid electrolytic capacitor element 16 and the cathode lead terminal 11 are connected by the conductive adhesive 12, the tantalum wire on the anode conductor side of the solid electrolytic capacitor element 16 is welded to the anode terminal 12. did. Further, the capacitor element 16 was covered with epoxy resin 13 to complete the solid electrolytic capacitor 17 shown in FIG.

Next, as Example 2, a solid electrolytic capacitor according to a modification of the above embodiment was manufactured. Example 2
The solid electrolytic capacitor of No. 2 is obtained by adding carbon particles, which are conductive particles, to the conductive polymer intermediate layer 4 of the solid electrolytic capacitor of Example 1 described above.

In the method for producing a solid electrolytic capacitor of Example 2, a maximum diameter was added to an n-butanol solution containing 1 mol / l of EDT as a monomer and 1 mol / l of iron (III) p-toluenesulfonate as an oxidant. Was used as a polymerization liquid in which 10 wt% of carbon particles which are conductive particles having a particle size of 1 μm or less were mixed. The manufacturing method of the solid electrolytic capacitor of Example 1 is the same as that of Example 1 except that the polymerization liquid contains carbon particles.

Further, a monomer solution containing EDT,
Iron (III) p-toluenesulfonate 1mo which is an oxidizing agent
The oxidant solution containing 1 / l and the oxidant solution is separately prepared, and carbon particles having a maximum diameter of 1 μm or less are contained in at least one of the oxidant solutions, and the sinter pellet is impregnated with the monomer solution. To form a conductive cathode layer made of EDT polymer on the surface of the sintered pellet.

The conductive conductive polymer intermediate layer 4 of the EDT polymer formed by using the above-mentioned polymerization solution is provided with a protrusion formed of carbon particles 8 as shown in FIG. 3, and the protrusion is a cathode conductor. Because it adheres to the carbon particles 11 of 5,
The resistance value depending on the contact between the conductive polymer intermediate layer 4 and the carbon particles 11 can be reduced, and the equivalent series resistance of the solid electrolytic capacitor element can be reduced.

Furthermore, as a third embodiment, the above-mentioned first embodiment
A solid electrolytic capacitor according to the modified example was manufactured. The solid electrolytic capacitor of Example 3 is obtained by adding EDT polymer fine particles as conductive particles to the conductive polymer intermediate layer of the solid electrolytic capacitor of Example 1 described above.

The polymerization liquid used for producing the solid electrolytic capacitor according to Example 3 was prepared by adding ED to n-butanol solution.
T1 mol / l and iron (III) p-toluenesulfonate
2 mol / l was mixed and allowed to stand at room temperature for about 30 hours to produce EDT polymer fine particles having a maximum diameter of about 100 μm in the n-butanol solution. The polymerization liquid thus prepared is a suspension in which EDT and EDT polymer fine particles are mixed. The method for manufacturing the solid electrolytic capacitor according to Example 3 is the same as the method for manufacturing the solid electrolytic capacitor according to Example 1 above, except that EDT and EDT polymer particles are mixed in the polymerization liquid.

By immersing the pellets of the sintered body having the solid electrolyte layer produced by the same method as in Example 1 above into the above-mentioned polymer solution which was sufficiently stirred, the cathode layer containing the EDT polymer fine particles was formed. Formed.

The conductive conductive polymer intermediate layer 4 made of the EDT polymer formed by using the above-mentioned polymerization solution is shown in FIG.
The protrusions are made of polymer fine particles 8 of EDT, and the protrusions adhere to the surfaces of the carbon particles 11 of the cathode conductor 5. In this way, the resistance value depending on the contact between the conductive polymer intermediate layer 4 and the carbon particles 11 can be reduced, and the equivalent series resistance of the solid electrolytic capacitor element can be reduced.

Comparative Example 1. As Comparative Example 1, a conventional solid electrolytic capacitor (Conventional Example 1) in which the solid electrolyte layer and the conductive polymer intermediate layer have the same hardness was manufactured. Specifically, the polypyrrole forming step is performed in the same manner as in Example 1 above.
After the solid electrolyte layer was formed on the fired pellets by repeating 0 times, the same polypyrrole forming step was repeated 20 times to form the conductive polymer intermediate layer on the solid electrolyte layer to manufacture a solid electrolytic capacitor. The method of manufacturing the solid electrolytic capacitor of Conventional Example 1 is the same as that of the solid electrolytic capacitor of Example 1 except for the method of forming the conductive polymer intermediate layer described above.

Comparative Example 2. As Comparative Example 2, a conventional solid electrolytic capacitor (Conventional Example 2) including a conductive polymer intermediate layer formed by an electrolytic polymerization method was manufactured. Specifically, after the solid electrolyte layer was formed on the pellet of the fired body by the same method as in Example 1, azetonitrile containing 0.3 mol / l of pyrrole as a monomer and 0.3 mol / l of dodecylbenzenesulfonic acid was used. Immerse the above fired pellets in an electrolytic solution consisting of a solution,
Electrolytic polymerization was carried out at a constant voltage of about 20 minutes to form a conductive polymer intermediate layer on the solid electrolyte layer. The method of manufacturing the solid electrolytic capacitor of Conventional Example 2 is the same as that of the solid electrolytic capacitor of Example 1 except for the method of forming the conductive polymer intermediate layer described above.

Next, a bias voltage of 1.0 V was applied to each of the solid electrolytic capacitors of Examples 1 to 3 and Conventional Examples 1 and 2 and impedance frequency characteristics were measured at 100 Hz to 40 MHz. Table 2 shows the equivalent series resistance at the resonance frequency of each solid electrolytic capacitor and the tangent (tan δ) of the loss angle at 120 Hz.

[0057]

[Table 2]

From Table 2 above, the solid electrolytic capacitors of Examples 1 to 3 are all equivalent series resistance and tangent of loss angle (tan δ) as compared with the solid electrolytic capacitors of Conventional Examples 1 and 2.
It turns out that both are improved.

[0059]

According to the solid electrolytic capacitor of the present invention,
By interposing a soft conductive polymer intermediate layer between the cathode conductor and the solid electrolyte layer, the conductive polymer intermediate layer is adhered to the carbon particles contained in the cathode conductor, and the conductive polymer intermediate layer and carbon particles By reducing the resistance value depending on the contact of, the equivalent series resistance and loss of the solid electrolytic capacitor are reduced.

According to the solid electrolytic capacitor of the present invention, the hardness of the solid electrolyte layer is made larger than the hardness of the conductive polymer intermediate layer, thereby improving the degree of adhesion between the conductive polymer intermediate layer and the carbon particles of the cathode conductor. Therefore, the equivalent series resistance and loss of the capacitor can be reduced.

According to the solid electrolytic capacitor of the present invention, the carbon contained in the conductive polymer intermediate layer and the cathode conductor is provided by providing the conductive polymer intermediate layer with the protrusion and bringing the protrusion into close contact with the cathode conductor. Improves adhesion with particles,
The equivalent series resistance of the capacitor can be reduced.

According to the solid electrolytic capacitor of the present invention, the conductive polymer intermediate layer is made to contain the conductive particles, the conductive polymer intermediate layer is provided with the soft protrusion, and the protrusion is brought into close contact with the cathode conductor. Thus, the equivalent series resistance and loss of the capacitor can be reduced.

According to the method for producing a solid electrolytic capacitor of the present invention, a conductive polymer intermediate layer having a high flexibility is formed by chemical polymerization between the cathode conductor and the solid electrolyte layer to form the conductive polymer intermediate layer as the cathode. It is possible to reduce the equivalent series resistance and loss of the capacitor by bringing the carbon particles contained in the conductor into close contact with each other to reduce the resistance value depending on the junction between the conductive polymer intermediate layer and the carbon particles.

According to the method for producing a solid electrolytic capacitor of the present invention, a soft conductive polymer having protrusions by chemical polymerization using a polymerization solution containing conductive particles in a mixed solution of a monomer solution and an oxidant solution. By forming the intermediate layer, the resistance value depending on the bonding between the conductive polymer intermediate layer and the carbon particles contained in the cathode conductor can be reduced, and the equivalent series resistance of the capacitor can be reduced.

According to the method for producing a solid electrolytic capacitor of the present invention, a monomer solution and an oxidant solution are mixed, a polymer of the monomer is produced in the mixed solution, and the mixed solution containing the monomer and the polymer is polymerized. By forming a conductive polymer intermediate layer having a protrusion as a liquid, the resistance value depending on the bonding between the conductive polymer intermediate layer and the carbon particles contained in the cathode conductor is reduced, and the equivalent series of the capacitor is reduced. The resistance can be reduced.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view showing an interface between a conductive polymer intermediate layer and a cathode conductor of a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view showing an interface between a conductive polymer intermediate layer and a cathode conductor of a solid electrolytic capacitor according to a modified example of the embodiment of the present invention.

FIG. 4 shows a cross-sectional view of a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view showing an interface between a solid electrolyte layer and a cathode conductor of a solid electrolytic capacitor according to a conventional technique.

[Explanation of symbols]

1 ... Anode conductor, 2 ... Dielectric layer, 3 ... Solid electrolyte layer, 4 ...
Conductive polymer intermediate layer, 5 ... Cathode conductor, 8 ... Conductive particles, 9 ... Carbon particle group, 11 ... Carbon particles, 16 ...
Solid electrolytic capacitor.

Front page continuation (72) Inventor Yoshihiko Tsujikawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-10-32145 (JP, A) JP-A-7-94368 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01G 9/028 H01G 9/04

Claims (3)

(57) [Claims] 1. A solid electrolyte layer forming step of forming a solid electrolyte layer on an anode conductor made of a metal having a valve action via a dielectric layer, and an oxidant solution containing a monomer solution containing a monomer and an oxidant. And containing conductive particles of the above monomers
By using a liquid, the chemical polymerization rather small hardness than the solid electrolyte layer made of the polymer and the cathode conductor side
In the conductive polymer intermediate layer forming step of forming on the surface of the solid electrolyte layer, a conductive polymer intermediate layer having a protruding portion by conductive particles of the monomer, carbon particles protruding to the conductive polymer intermediate layer side A step of forming a cathode conductor having a group on the surface of the conductive polymer intermediate layer and bringing the protrusions of the conductive polymer intermediate layer into close contact with the carbon particle group. Manufacturing method of solid electrolytic capacitor. 2. In the step of forming the conductive polymer intermediate layer, the monomer solution and the oxidant solution are mixed and a part of the monomer is oxidatively polymerized to produce a polymer of the monomer. The method for producing a solid electrolytic capacitor according to claim 1 , wherein the mixed solution in which a monomer is mixed is prepared, and the conductive polymer intermediate layer having the protrusion is formed using the mixed solution. . Wherein said monomer is or claim 1, characterized in that a 3,4-ethylenedioxythiophene
2. The method for producing a solid electrolytic capacitor as described in 2 .