JP2000232036A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity of a solid electrolytic capacitor by reducing the ESR by forming a conductive high polymer layer by dipping an anode conductor in a polymeric liquid prepared by adding a monomer to a suspension containing conductive polymer particles. SOLUTION: Chemically formed sintered pellets are obtained by chemically forming dielectric layers 2 on the surfaces of fine sintered particles 1 of tantalum which is a valve metal by using the particles 1 as anode conductors. After the pellets are dipped in a monomer solution, solid electrolyte layers 3 of a conductive macromolecular polymer are formed on the surfaces of the dielectric layers 2 in the pores of the pellets. Then conductive high polymer layers 4 composed of EDT polymer are formed on the surfaces of the electrolyte layers 3 by repeating a step of dipping the pellets carrying the electrolyte layers 3 in a suspension prepared by adding EDT to the suspension after adjustment by polymerizing, for example, ethylene dioxythiophene with EDT, a step of pulling out the pellets, and a step of making EDT polymerization. Since the high polymer layers 4 have uneven surfaces formed of conductive polymer particles, the joint surfaces of the layers 4 which come into contract with cathode conductor layers 5 formed on the layers 4 increase and the ESR is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 having a conductive polymer layer.

[0002]

2. Description of the Related Art In recent years, in electronic equipment using a solid electrolytic capacitor, the frequency and current of an integrated circuit have been remarkably increased. Accordingly, a solid electrolytic capacitor having a low equivalent series resistance (hereinafter, referred to as ESR) and a large capacitance is required. Usually, the solid electrolytic capacitor has a structure in which an anode conductor, a dielectric layer, a solid electrolyte layer, and a cathode conductor layer are arranged in the above order.

Next, a method for manufacturing a solid electrolytic capacitor will be described. First, a sintered pellet of a film-forming valve metal such as tantalum and aluminum is used as an anode conductor,
The sintered pellet is anodized in an electrolyte solution to form a dielectric layer on its surface. Next, the sintered body pellet having the dielectric layer is immersed in a manganese nitrate solution and sintered to form a manganese dioxide solid electrolyte layer on the surface of the dielectric layer. Finally, a solid electrolytic capacitor is completed by forming a cathode conductor layer on the solid electrolyte layer.

The factors that determine the ESR are the resistances of the solid electrolyte layer, anode conductor, cathode conductor layer, negative anode conductor terminal, and dielectric layer, which are conductive paths for charging / discharging current of the capacitor. It was thought to be an electrolyte.

In view of the above factors, manganese dioxide conventionally used as a solid electrolyte has a conductivity of 0.1 to 1 S /
cm, a conductive polymer compound having a higher conductivity was found. When the solid electrolyte layer is formed of a conductive polymer compound, for example, polypyrrole, the tantalum has a high conductivity of about 100 S / cm, has stability over time, and heat and moisture resistance, and has good high-frequency characteristics. A solid electrolytic capacitor is obtained (JP-A-2-130)
906).

In order to form such a solid electrolyte layer, which is a conductive polymer compound, on the surface of the dielectric layer, chemical polymerization is used because the dielectric layer is non-conductive. The chemical polymerization method is a method of immersing a sintered body pellet having a dielectric layer formed therein in a mixed solution obtained by mixing a monomer solution and a compound acting as an oxidizing agent, or a method of immersing a monomer solution in a sintered body pellet having a dielectric layer formed therein. And then immersing it in an oxidizing agent solution. In this way, a conductive polymer layer is formed on the surface of the dielectric layer formed inside the pores of the sintered pellet. .

Further, electrolytic polymerization is performed by using the conductive polymer layer formed by the above-described chemical polymerization method as a preliminary electrode layer,
A sufficient amount of solid electrolyte layer may be secured. in this case,
A sintered body pellet having a conductive polymer layer is immersed in an electrolytic solution containing a monomer, the conductive polymer layer is brought into contact with an electrode to serve as an anode, and a cathode plate is attached in the polymer solution.
A voltage is applied between both electrodes to grow a conductive polymer layer by electrolytic polymerization. The conductive polymer layer formed on the surface of the dielectric layer deep in the pores of such a sintered pellet,
It conducts to a cathode conductor layer to be formed later as a solid electrolyte layer.

[0008]

However, the above-mentioned conductive polymer layer has the following problems. Since the growth of the conductive polymer layer generated by chemical polymerization depends on the adsorption and lamination of the polymer generated in the form of particles on the surface of the sintered pellet, the amount of the polymer solution that penetrates into the pores of the sintered pellet Is limited, and the solubility of the monomer in the solvent is limited. Therefore, the growth rate of the conductive polymer layer is slow, and the thickness of the conductive polymer layer may be insufficient, resulting in poor productivity. Further, the strength of the conductive polymer formed by chemical polymerization is not sufficient. In other words, when the conductive polymer layer is formed by chemical polymerization,
As a result, there is a problem that the dielectric layer on the surface of the sintered body is damaged, a leakage current is generated, and the capacitor is deteriorated.

Further, the conductive polymer layer formed by electrolytic polymerization has a higher conductivity, is stronger, and is smoother than that formed by chemical polymerization. However, since the conductive polymer layer formed by electrolytic polymerization is strong and smooth, the adhesion to the cathode conductor layer is poor,
There is a problem that it is difficult to increase the contact area with the cathode conductor layer.

Further, even if the electrolyte layer is formed of a conductive polymer having high conductivity as described above, there is a problem that the ERS of the solid electrolytic capacitor does not fall below a certain value.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing a solid electrolytic capacitor capable of manufacturing a solid electrolytic capacitor having reduced ERS with high productivity.

[0012]

Considering the above problems, it is considered that the ESR of a capacitor is much larger than the total value of the resistance of each component such as a dielectric layer and an electrolyte layer in a conductive path. There was found. Also, the cathode conductor layer is a suspension paint containing conductive particles,
Apply to the surface of the sintered body pellet with the electrolyte layer formed,
The conductive particles are formed by drying and solidifying, and the conductive particles are bonded to other conductive particles and the electrolyte layer to develop conductivity in the cathode conductor layer. It has been found that the electric resistance depending on the junction with the metal is extremely large. That is, it has been found that the main factor of the ESR is not the electrolyte layer but the contact resistance between the conductive particles contained in the cathode conductor layer and the solid electrolyte layer, as has been considered so far.

In order to solve the above problems, a conductive polymer layer made of a conductive polymer compound having high plasticity or flexibility is formed at the interface between the solid electrolyte layer and the cathode conductor layer, and the conductive polymer layer is The bonding area of the cathode conductor layer with the conductive fine particles was increased. Further, as shown in FIG. 4, conductive fine particles 8 having plasticity or flexibility are mixed in the conductive polymer layer 4, and irregularities are provided at the interface 12 of the conductive polymer layer 4. And the junction area between the anode and the cathode conductor layer 9 were further increased. By providing such a conductive polymer layer 4,
The ESR of the capacitor is reduced.

Next, a method for forming the conductive polymer layer will be described. First, a mixed solution is prepared by mixing a monomer and an oxidizing agent in an equimolar number with the monomer. In this mixture, the monomer is oxidatively polymerized to produce conductive polymer particles of the monomer. While the concentration of the conductive polymer particles in the mixture satisfies a predetermined value, the sintered body pellet having the electrolyte layer formed thereon is immersed in the mixture, and the mixture is applied to an outer layer portion thereof. Is removed and polymerized to form a conductive conductive polymer layer containing conductive polymer particles on the electrolyte layer.

More specifically, the mixed solution is obtained by mixing a monomer solution containing a monomer and an oxidizing agent solution containing an oxidizing agent, and oxidizing and polymerizing the monomer at an ambient temperature of room temperature to 70 ° C. to form a conductive polymer. It is generated. As shown in FIG. 5, the concentration of the conductive polymer particles in the mixed solution changes over time, and thus the time during which the sintered pellet can be impregnated is limited to t ₁ . Therefore, the step of forming the bonding electrolyte layer is complicated and redundant, and there is a problem in productivity.

The method of manufacturing a solid electrolytic capacitor according to the present invention is to manufacture a conductive polymer layer of a solid electrolytic capacitor by a method having high productivity. Specifically, the method for producing a solid electrolytic capacitor of the present invention is a polymerization liquid preparation step of preparing a polymerization liquid by adding a monomer that is a basic unit of a conductive polymer to a suspension containing conductive polymer particles, Immersing the anode conductor on which the dielectric layer is formed in a polymerization liquid, and forming a conductive polymer layer containing conductive polymer particles on the dielectric layer. ,
It is intended to manufacture a solid electrolytic capacitor using a conductive polymer layer as a solid electrolyte layer.

Further, according to the method for manufacturing a solid electrolytic capacitor of the present invention, the anode conductor on which the electrolyte layer is formed via the dielectric layer is immersed in the above-mentioned polymerization solution to form conductive polymer particles on the electrolyte layer. A conductive polymer layer may be formed.

In the method for producing a solid electrolytic capacitor of the present invention, the polymerization solution is prepared by preparing a monomer solution containing a monomer, an oxidizing agent solution having an oxidizing action and a suspension, or a monomer solution containing a monomer. And a suspension having an oxidizing action are preferably prepared.

Further, according to the method for manufacturing a solid electrolytic capacitor of the present invention, the suspension is mixed with a monomer solution containing a monomer and an oxidizing agent solution containing an oxidizing agent, and the monomer is subjected to an oxidative polymerization reaction. It is preferable that the conductive polymer is generated until the polymerization reaction is completed. It is more preferable to prepare the above suspension at an atmosphere temperature of -5 ° C to 70 ° C.

In the method for producing a solid electrolytic capacitor of the present invention, it is preferable that the oxidizing agent is a complex of trivalent iron ions.

In the method for manufacturing a solid electrolytic capacitor according to the present invention, the number of moles of the monomer in the mixture of the monomer solution and the oxidizing agent solution is 0.1% of the number of moles of the oxidizing agent.
Preferably, it is twice to 0.9 times.

Further, according to the method for manufacturing a solid electrolytic capacitor of the present invention, the conductive polymer layer is provided with at least one of plasticity and flexibility so as to be in close contact with the cathode conductor. Can further be manufactured.

In the method for manufacturing a solid electrolytic capacitor according to the present invention, the weight of the conductive polymer particles contained in the conductive polymer layer is set to 30% or less of the weight of the conductive polymer layer. 100 μm
It is preferable to set the following.

Specifically, in the method for producing a solid electrolytic capacitor of the present invention, it is preferable that the monomer is a heterocyclic organic compound or an aromatic organic compound, and more specifically,
Monomer, pyrrole, pyrrole derivative, thiophene, thiophene derivative, furan, furan derivative, selenophene, selenophene derivative, aniline, aniline derivative, phenylene, phenylene derivative, naphthalene, naphthalene derivative, anthracene, anthracene derivative , Pyrene, a derivative of pyrene, azulene, a derivative of azulene, and 3,4-ethylenedioxythiophene.

More specifically, in the method for producing a solid electrolytic capacitor of the present invention, the number of moles of 3,4-ethylenedioxythiophene contained in the monomer solution is changed to the p-toluenesulfonic acid contained in the oxidant solution. Preferably, the suspension is prepared by mixing the monomer solution and the oxidizing agent solution so that the molar number is 0.05 to 0.4 times the number of moles of iron (III).

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solid electrolytic capacitor according to an embodiment of the present invention will be described. The solid electrolytic capacitor of the present embodiment includes a conductive polymer layer made of a conductive polymer compound between the solid electrolyte layer and the cathode conductor layer. The conductive polymer layer has at least one of plasticity and flexibility so that it can be in close contact with the cathode conductor layer, and has irregularities formed by the conductive polymer particles. Due to the irregularities made of the conductive polymer particles, the bonding surface where the cathode conductor layer and the conductive polymer layer are in contact with each other is increased.

Next, a method for forming a conductive polymer layer will be described. First, a monomer which is a basic unit of the conductive polymer in the suspension containing the conductive polymer particles is mixed to prepare a polymerization solution. Next, the conductive polymer layer is formed on the electrolyte layer by immersing the anode conductor on which the electrolyte is formed via the dielectric layer in the above-mentioned polymerization solution. The suspension used in this step had no change in the concentration of the conductive polymer with time, and was obtained based on the verification described below.

The conductive polymer compound having conductivity which can be used as the conductive polymer layer of the solid electrolytic capacitor is obtained by polymerizing and synthesizing a monomer by a dehydrogenation reaction with an oxidizing agent. Specifically, heterocyclic compounds such as pyrrole, thiophene, and derivatives thereof are polymerized and synthesized by bonding mainly with elimination of hydrogen at the 2,5-positions, and aromatic compounds are bonded by polymerization at the para-position. Is done.

For example, by oxidative polymerization using an oxidizing agent,
In the terminal heterocycle of the polymer polymer chain PPy (n) of polypyrrole synthesized from n pyrroles, the hydrogen group at the 2- or 5-position is eliminated, and the 2- or 5-position of Py composed of pyrrole as a monomer is further removed. Is eliminated, whereby polymer polymer chains PPy (n) and Py are synthesized,
A polymer polymer chain PPy (n + 1) of polypyrrole composed of n + 1 pyrroles is generated.

Such a mode of reaction also applies to oxidative polymerization in which a conductive polymer is formed. That is, since the oxidative polymerization reaction of the conductive polymer is a sequential reaction, the progress of the polymerization is limited by the amount of the oxidizing agent, and the reaction stops when the entire amount of the oxidizing agent is consumed. For example, when synthesizing pyrrole, up to twice the number of moles of pyrrole is consumed in the oxidizing agent to stop the reaction. Further, in the oxidative polymerization reaction, the degree of polymerization of the conductive polymer, the molecular weight distribution of the conductive polymer, and the like can be controlled by the monomer concentration, the oxidizing agent concentration, and the polymerization reaction temperature. That is, the degree of polymerization of the conductive polymer, the molecular weight distribution of the conductive polymer, and the like can be controlled by the mixing ratio of the monomer and the oxidizing agent.

Specifically, when a monomer solution containing a monomer is mixed with an oxidizing agent solution containing an oxidizing agent, and the monomer is oxidized and polymerized to prepare a suspension containing conductive polymer particles, By making the number of moles of the monomer in the solution smaller than the number of moles of the oxidizing agent in the oxidizing agent solution and completing the oxidative polymerization of the monomer in suspension, the composition of the conductive polymer particles, A suspension whose concentration does not change over time can be obtained. The suspension is preferably prepared in an atmosphere at -5 ° C to 70 ° C.

Even if the suspension was left in the sealed container for 250 hours, the liquid state of the suspension, the sedimentation of the conductive polymer particles, and the like did not change. Further, the ambient temperature is set to -5 ° C.
Even when the temperature was changed in the range of ４０40 ° C. and the suspension was allowed to stand in a sealed container for 250 hours, the liquid state of the suspension and the sedimentation of the conductive polymer particles did not change with time. That is, at an ambient temperature of −5 ° C. to 40 ° C., the concentration of the conductive polymer particles in the suspension prepared as described above does not change with time.

[0033] A monomer is added again to the suspension prepared as described above, and a polymerization solution prepared so that the newly added monomer is oxidatively polymerized by the oxidizing agent remaining in the suspension. Then, the conductive polymer layer of the solid electrolytic capacitor of the present embodiment is formed. FIG. 1 shows the concentration of the conductive polymer in the suspension prepared by mixing the monomer solution and the oxidizing agent solution, and the concentration of the conductive polymer in the polymerization solution prepared by re-adding the monomer to the suspension. As shown in the figure, the concentration of the polymer particles after completing the preparation of the suspension is stable over time.

In the above embodiment, the polymerization solution is prepared by adding the monomer to the suspension in which the oxidizing agent remains, that is, the suspension having the oxidizing effect. However, the present invention is not limited to this. is not. For example, a polymerization solution may be prepared by mixing an oxidizing agent solution having an oxidizing action and a monomer solution and a suspension containing a monomer, or a monomer solution containing a monomer and a suspension having an oxidizing action. May be mixed to prepare a polymerization solution.

When forming the conductive polymer layer of the solid electrolytic capacitor, the monomer solution and the oxidizing agent solution are mixed such that the number of moles of the monomer is 1/9 to 8/9 times the number of moles of the oxidizing agent. Is used. Specifically, the number of moles of the monomer is 1/9 times the number of moles of the oxidizing agent,
It is more preferable to use a suspension prepared by stirring at 24 ° C. for 24 hours to carry out an oxidative polymerization reaction. Since the suspension thus prepared is most excellent in liquid state and pot life, by forming the conductive polymer layer of the solid electrolytic capacitor using such a suspension, the ESR and L of the solid electrolytic capacitor can be reduced.
The C defect rate can be reduced most.

As described above, when preparing the suspension, the number of moles of the monomer is 1/9 to 8 times the number of moles of the oxidizing agent.
/ 9 times is preferable, but the present invention is not limited to this, and the number of moles of the monomer may be 0.1 to 0.9 times the number of moles of the oxidizing agent. Further, the monomer is 3,4-ethylenedioxythiophene, and the oxidizing agent is p
When iron (III) toluenesulfonate is used, the number of moles of the monomer is 0.05 to 0.4 times the number of moles of the oxidizing agent.
It should just be double.

The conductive polymer layer thus prepared has at least one of plasticity and flexibility so that it can be in close contact with the cathode conductor layer, and has irregularities formed by conductive polymer particles. is there. The form of the irregularities is
The film-shaped polymer layer has a shape in which the particulate polymer is scattered, and the polymerization ratio of the particulate polymer is proportional to the molar ratio of the monomer added for the polymerization reaction in the liquid to the oxidizing agent in the initial stage. Is increased or decreased. Due to the irregularities formed of the conductive polymer particles, the bonding surface at which the cathode conductor layer and the conductive polymer layer are in contact with each other is increased, so that the ESR and LC failure rate of the solid electrolytic capacitor are reduced.

Further, in order to increase the bonding surface at which the cathode conductor layer and the conductive polymer layer come into contact with each other, it is preferable that the size of the conductive polymer particles contained in the conductive polymer layer be 100 μm or less. More preferably, the weight of the conductive polymer particles is 30% or less of the weight of the conductive polymer layer.

Specifically, it is preferable to use a monomer as a heterocyclic organic compound or an aromatic organic compound. Further, specifically, as a monomer, pyrrole,
Pyrrole derivatives, thiophenes, thiophene derivatives,
Furan, furan derivatives, selenophene, selenophene derivatives, aniline, aniline derivatives, phenylene,
Phenylene derivatives, naphthalene, naphthalene derivatives, anthracene, anthracene derivatives, pyrene, pyrene derivatives, azulene, azulene derivatives, and 3,
It is preferably selected from 4-ethylenedioxythiophene and the like. Further, it is preferable to use a trivalent iron ion complex or the like as the oxidizing agent. The polymer particles formed from such an oxidizing agent and a monomer can increase the bonding surface where the cathode conductor layer and the conductive polymer layer come into contact.

Hereinafter, a solid electrolytic capacitor having a conductive polymer layer formed by the above-described method will be specifically described. As anode conductors for solid electrolytic capacitors, tantalum, aluminum, titanium, niobium, zirconium,
A metal having a valve action such as zinc is used. Further, in order to increase the capacitance, the anode conductor is preferably a sintered body made of fine particles of the above metal, or a metal foil that has been subjected to a surface enlargement treatment such as etching. On the surface of the anode conductor, a dielectric layer formed by a known electrochemical anodic oxidation method is formed.

Further, a solid electrolyte layer is formed on the dielectric layer. As the solid electrolyte layer, a conductive oxide such as manganese dioxide or a conductive polymer compound is used.

Further, a cathode conductor layer is formed on the solid electrolyte layer via the conductive polymer layer formed by the above method. Usually, the cathode conductor layer is composed of a carbon layer and a silver paste layer, and the carbon layer is formed of a silver paste and a conductive polymer layer in order to improve the adhesion between the silver paste layer and the conductive polymer layer. And intervenes between them. The cathode conductor layer is formed by immersing the anode conductor on which the conductive polymer layer is formed in a suspension aqueous solution containing fine carbon particles, applying the suspension aqueous solution on the conductive polymer layer, and then drying and solidifying the water. Then, a carbon layer is formed, and the anode conductor having the carbon layer formed thereon is immersed in a silver paint solution, and then dried and solidified to form a silver paste layer. In addition, the cathode conductor layer may be formed only from the silver paste layer.

The solid electrolytic capacitor of the above embodiment is
Although the structure has an electrolyte and a conductive polymer layer between the dielectric layer and the cathode conductor layer, the present invention is not limited to this. A molecular layer may be formed, and a cathode conductor layer may be formed on the conductive polymer layer.

[0044]

Embodiments of the present invention will be described below.

Example 1 As Example 1, a tantalum electrolytic capacitor 17 shown in FIGS. 2 and 3 was manufactured. Specifically, polypyrrole, a conductive polymer compound, is used as the solid electrolyte layer, a fine powder sintered body of tantalum, which is a valve metal, is used as the anode conductor, and the conductive polymer layer is formed by a chemical oxidation polymerization method. It was adopted.

First, a fine tantalum powder of about 70,000 μF · V / g was molded and sintered together with a tantalum wire lead for drawing out an anode to have dimensions of 1.4 mm × 3.0 mm ×
A 3.8 mm tantalum sintered body 1 was formed. Next, the tantalum sintered body 1 was formed in a phosphoric acid aqueous solution at a formation voltage of 30 V, a dielectric layer 2 was formed on the surface, and the formed sintered body pellets were obtained through washing and drying.

Next, isopropyl alcohol was added to 10 vol.
0.1 mol / l pyrrole in an aqueous solution containing 1%
And a monomer solution was prepared. Further, an aqueous solution containing 10 vol% of isopropyl alcohol was added with 0.1 mol / mol of iron (III) sulfate as an oxidizing agent.
1) As another additive, a sodium salt of alkylnaphthalenesulfonate ion was dissolved at 0.05 mol / l to prepare an oxidizing agent solution.

Subsequently, the chemically-formed sintered compact pellet prepared above is immersed in a monomer solution, and then immersed in an oxidizing agent solution, so that the surface of the dielectric layer 2 inside the pores of the sintered pellet is electrically conductive. A water-soluble polymer was formed, washed and dried. This operation was repeated 30 times, and a chemical conversion voltage of 30 V was appropriately applied in a 0.1% phosphoric acid aqueous solution to perform re-chemical formation for repairing the dielectric layer 2. Next, the sintered body pellets are washed in pure water at about 90 ° C., and further dried in an atmosphere at about 120 ° C. to form a sufficient amount of a high quality solid electrolyte layer 3 on the dielectric layer 2. did.

Next, an n-butanol solution 9 containing 1.0 g of ethylenedioxythiophene (hereinafter referred to as EDT) and 40 wt% of iron (III) p-toluenesulfonate was prepared.
5 g and 17 g of n-butanol were mixed in a tightly-sealed container, and a polymerization reaction was performed at an ambient temperature of 40 ° C. for 24 hours to prepare a suspension.

Further, 8 g of EDT was added to 113 g of the suspension cooled to about 5 ° C. to 15 ° C., and the mixture was stirred with a stirrer to prepare a polymerization solution. 3 was immersed in the polymerization liquid for 3 minutes. After pulling up the sintered body pellets from the polymerization solution, the solvent was vaporized in an atmosphere at 30 ° C. to 40 ° C. to form a polymer precursor. Next, the polymerization of the EDT polymer was promoted in an atmosphere at 80 ° C. to 160 ° C. for 20 minutes. This EDT polymerization step was repeated 1 to 4 times. next,
Washing the sintered pellet in isopropyl alcohol,
A chemical conversion voltage of 20 V is applied in an aqueous solution of 0.1% phosphoric acid-10% isopropyl alcohol to re-form the dielectric layer 2, and further, the sintered body pellet is purified in pure water at 40 ° C. to 90 ° C. Was washed, and the sintered body pellets were dried in an atmosphere at room temperature to 120 ° C. Thus, the conductive polymer layer 4 made of the EDT polymer was formed.

Next, the sintered body pellet having the conductive polymer layer 4 formed thereon is immersed in an aqueous suspension liquid containing fine carbon particles, and the surface of the conductive polymer layer 4 is coated with the aqueous suspension liquid. It was left at 30 ° C. for 30 minutes, dried and solidified to form a carbon layer 9. Furthermore, the sintered compact having the carbon layer 9 formed thereon was similarly immersed in a silver paint solution, and then dried and solidified at 145 ° C. for 1 hour to form a silver paint layer 10. Thus, the carbon layer 9
And the cathode conductor layer 5 composed of the silver paint layer 10 is completed,
The tantalum solid electrolytic capacitor element 16 was completed.

Next, the cathode side was connected to the cathode external lead-out terminal 13 using the conductive adhesive 12, and the tantalum wire previously attached to the anode side was welded to the anode external lead-out terminal 14. Further, the capacitor element 16 was covered with an epoxy resin 15 to produce a solid electrolytic capacitor 17. The ESR of the produced capacitor was measured with an impedance analyzer, and the applied voltage was 6 V, and the leakage current (LC) after 30 seconds was measured.

(Example 2) As Example 2, a tantalum electrolytic capacitor was manufactured as follows. First, a dielectric layer was formed on the same sintered pellet as in Example 1 in the same manner as in Example 1 to produce a chemically-formed sintered pellet. Next, an n-butanol solution 95 containing 1.5 g of EDT and 40 wt% of iron (III) p-toluenesulfonate was used.
g and n-butanol in a 17 g sealed vessel,
A polymerization reaction was performed at an ambient temperature of 40 ° C. for 24 hours to prepare a suspension.

Further, the suspension 1 cooled to about 5 to 15 ° C.
8 g of EDT was added to 13 g, and the mixture was stirred with a stirrer to prepare a polymerization solution.
C., and the formed sintered compact pellets were immersed for 20 minutes. Thereafter, the sintered pellets are pulled up from the polymerization solution so as not to cause liquid splashing and the like, and the pellets are placed in an atmosphere of about 40 ° C. for about 3 hours.
After a polymerization reaction for about 10 hours, take out at room temperature
After leaving to cool for minutes, the EDT was polymerized. This EDT polymerization step was repeated 5 to 10 times. Next, the sintered body pellet is washed in isopropyl alcohol, and a formation voltage of 20 V is applied in an aqueous solution of 10 wt% isopropyl alcohol containing 0.1 wt% phosphoric acid for 10 minutes to re-form the dielectric layer. , And further washed in pure water at 40 to 90 ° C, and dried in an atmosphere at room temperature to 120 ° C. Thus, an electrolyte layer made of a conductive polymer compound made of an EDT polymer was formed. Next, a carbon layer and a silver paint layer were formed in the same manner as in Example 1, a tantalum solid electrolytic capacitor was manufactured, and ESR and LC were measured.

(Comparative Example 1) As Comparative Example 1, a tantalum solid electrolytic capacitor was manufactured as follows. A dielectric layer was formed in the same manner as in Example 1 using the same sintered pellets as in Example 1 above. Further, polypyrrole was formed as a solid electrolyte on the dielectric layer inside the pores of the sintered pellet.

Next, the sintered pellets on which the solid electrolyte layer was formed were mixed with a polymerization solution obtained by mixing 1 mol / l of EDT and an n-butanol solution containing 1 mol / l of iron (III) p-toluenesulfonate. Immerse for 3 minutes. Subsequently, the sintered body pellets were pulled out of the polymerization liquid, and left for 15 minutes in an atmosphere at room temperature to 40 ° C., and then left for 20 minutes in an atmosphere at about 80 ° C. to 160 ° C. to perform polymerization formation of EDT. . This EDT polymerization step was repeated 2 to 5 times to form a conductive polymer layer. Thereafter, a carbon layer and a silver paint layer were formed in the same manner as in Example 1, the positive and negative electrode terminals were attached, and a mold was formed using an epoxy exterior resin. A solid electrolytic capacitor of Comparative Example 1 was produced, and ESR and LC were measured. .

(Comparative Example 2) As Comparative Example 2, a tantalum solid electrolytic capacitor was manufactured as follows. The electrolyte layer of the tantalum solid electrolytic capacitor of Comparative Example 2 was EDT10
g, 95 g of iron (III) p-toluenesulfonate, and n
-17 g of butanol was mixed and prepared, and this was formed as a polymerization solution. Other manufacturing methods are described in Example 2 above.
Is the same as Further, the ESR and LC of the solid electrolytic capacitor of Comparative Example 2 were measured.

Comparative Example 3 As Comparative Example 3, a tantalum solid electrolytic capacitor was manufactured as follows. A dielectric layer was formed in the same manner as in Example 1 using the same sintered pellets as in Example 1 above. Furthermore, polypyrrole was formed as a solid electrolyte on the dielectric layer inside the pores of the sintered pellet. Next, 1 mol / l of EDT and an n-butanol solution containing 1 mol / l of iron (III) p-toluenesulfonate were mixed, and the mixture was stirred at about 5 ° C. for 90 hours. Then, the sintered body pellet on which the solid electrolyte layer was formed was immersed for 3 minutes. Furthermore, after pulling up the sintered compact pellets from the polymerization liquid, room temperature to 40 ° C.
For 15 minutes, followed by about 80-160 ° C
The mixture was allowed to stand for 20 minutes in the atmosphere described above to form EDT polymerization. This EDT polymerization step was repeated 2 to 5 times to form a conductive polymer layer. Thereafter, a carbon layer and a silver paint layer were formed in the same manner as in Example 1 described above, the positive and negative electrode terminals were attached, and a mold was formed using an epoxy exterior resin, to produce a solid electrolytic capacitor of Comparative Example 3, and ESR and LC were measured. It was measured.

The ESR and LC defect rates of the solid electrolytic capacitors of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in Table 1 below.
Shown in

[0060]

[Table 1]

Comparing the ESR and the LC defect rate, it is clear from Table 1 that the solid electrolytic capacitors of the examples are superior to the solid electrolytic capacitors of the comparative examples.

[0062]

As described above, according to the method for producing an electrolytic capacitor of the present invention, a polymerization solution is prepared by adding a monomer which is a basic unit of a conductive polymer to a suspension containing conductive polymer particles. Then, the anode conductor on which the dielectric layer is formed is immersed in a polymerization solution to form a conductive polymer layer containing conductive polymer particles on the dielectric layer. This is to manufacture a solid electrolytic capacitor having a solid electrolyte layer. According to the manufacturing method of the present invention, ES
An electrolytic capacitor having excellent R can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 shows the concentration of conductive polymer particles in a mixture of a monomer solution and an oxidizing agent solution used when forming a conductive polymer layer of a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the solid electrolytic capacitor according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of the solid electrolytic capacitor according to the embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view of a bonding interface between a conductive polymer layer and a cathode conductor layer of a solid electrolytic capacitor.

FIG. 5 shows the concentration of conductive polymer particles in a mixture of a monomer solution and an oxidant solution used when forming a conductive polymer layer of a solid electrolytic capacitor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... anode conductor, 2 ... dielectric layer, 3 ... electrolyte layer, 4 ... conductive polymer layer, 5 cathode conductor layer, 9 ... carbon layer, 10 ... silver paste layer.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Yoshihiko Tsujikawa, 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Hideo Hashimoto 1006 Kadoma, Kadoma, Kadoma, Osaka Pref. 72) Inventor Masakazu Tanahashi 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Toshitaka Kato 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (15)

[Claims] 1. An anode conductor made of a valve metal, a dielectric layer formed on a surface of the anode conductor, a solid electrolyte layer formed on a surface of the dielectric layer, and a surface provided on the surface of the solid electrolyte layer. A method for producing a solid electrolytic capacitor having a cathode conductor layer, wherein the production method comprises adding a monomer that is a basic unit of the conductive polymer to a suspension containing the conductive polymer particles to prepare a polymerization solution. A preparing step, immersing the anode conductor on which the dielectric layer is formed in the polymerization solution to form a conductive polymer layer containing the conductive polymer particles on the dielectric layer; A method for producing a solid electrolytic capacitor, comprising: a step of forming a molecular layer; and producing a solid electrolytic capacitor using the conductive polymer layer as the solid electrolyte layer. 2. An anode conductor made of a valve metal, a dielectric layer formed on the surface of the anode conductor, a solid electrolyte layer formed on the surface of the dielectric layer, and a surface provided on the surface of the solid electrolyte layer. In a method for manufacturing a solid electrolytic capacitor having a cathode conductor layer, a polymerization liquid preparation step of adding a monomer that is a basic unit of the conductive polymer to a suspension containing conductive polymer particles to prepare a polymerization liquid; The anode conductor on which the electrolyte layer is formed via a dielectric layer is immersed in the polymerization solution to form a conductive polymer layer containing the conductive polymer particles on the electrolyte layer. A method for manufacturing a solid electrolytic capacitor, comprising a step of forming a polymer layer. 3. The polymerization liquid is prepared by preparing a monomer solution containing the monomer, an oxidizing agent solution having an oxidizing action and the suspension, or has a oxidizing action with a monomer solution containing the monomer. 2. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein said suspension is one of prepared ones. 4. The polymerization liquid is prepared by preparing a monomer solution containing the monomer, an oxidizing agent solution having an oxidizing action and the suspension, or has a oxidizing action with a monomer solution containing the monomer. 3. The method for producing a solid electrolytic capacitor according to claim 2, wherein the suspension is one of prepared ones. 5. The suspension is obtained by mixing a monomer solution containing the monomer and an oxidizing agent solution containing an oxidizing agent, and subjecting the monomer to an oxidative polymerization reaction. The method for producing a solid electrolytic capacitor according to any one of claims 1 to 4, wherein a conductive polymer is generated. 6. The method according to claim 1, wherein the number of moles of the monomer in the mixture of the monomer solution and the oxidizing agent solution is 0.1 to 0.9 times the number of moles of the oxidizing agent. Item 6. The method for producing a solid electrolytic capacitor according to Item 5. 7. The method for producing a solid electrolytic capacitor according to claim 5, wherein the suspension is prepared at an ambient temperature of −5 ° C. to 70 ° C. 8. The method according to claim 5, wherein the oxidizing agent is a complex of trivalent iron ions. 9. The method according to claim 1, wherein the conductive polymer layer has at least one of plasticity and flexibility so as to be in close contact with the cathode conductor. The manufacturing method of the solid electrolytic capacitor described in the above. 10. The conductive polymer layer according to claim 1, wherein the weight of the conductive polymer particles contained in the conductive polymer layer is 30% or less of the weight of the conductive polymer layer.
The method for producing a solid electrolytic capacitor according to any one of the above. 11. The conductive polymer particles having a size of 1
2. The thickness is not more than 00 μm.
0. The method for manufacturing a solid electrolytic capacitor according to any one of the above items. 12. The method according to claim 1, wherein the monomer is a heterocyclic organic compound or an aromatic organic compound.
12. The method for manufacturing a solid electrolytic capacitor according to any one of items 11 to 11. 13. The method according to claim 13, wherein the monomer is pyrrole, a derivative of pyrrole, thiophene, a derivative of thiophene, furan,
Furan derivatives, selenophene, selenophene derivatives, aniline, aniline derivatives, phenylene, phenylene derivatives, naphthalene, naphthalene derivatives, anthracene, anthracene derivatives, pyrene, pyrene derivatives, azulene, azulene derivatives, and 3,4 The method for producing a solid electrolytic capacitor according to any one of claims 1 to 12, wherein the one is selected from the group consisting of -ethylenedioxythiophene. 14. The method according to claim 5, wherein the monomer is 3,4-ethylenedioxythiophene, and the oxidizing agent is iron (III) p-toluenesulfonate. The manufacturing method of the solid electrolytic capacitor described in the above. 15. The 3,4 contained in the monomer solution
The mole number of ethylenedioxythiophene is 0.05 to 0.4 times the mole number of iron (III) p-toluenesulfonate contained in the oxidizing agent solution. The manufacturing method of the solid electrolytic capacitor described in the above.