JP2001237146A - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state electrolytic capacitor having large capacitance, low equivalent series resistance and small dielectric loss, and its manufacturing method. SOLUTION: The solid-state electrolytic capacitor is composed of an anode electrode body consisting of a metal with valve function, an anode oxide film formed onto the anode electrode body and a high-molecular solid-state electrolyte containing an oxygen acquisitive metallic organic complex as an additive so as to inhibit the lowering of conductivity, and has a solid-state electrolytic layer formed on the anode oxide film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a solid electrolytic capacitor having a small size, a large capacity, and excellent high-frequency characteristics has been demanded. To meet this demand, Japanese Patent Application Laid-Open No. 2-130906 proposes a solid electrolytic capacitor having a solid electrolyte layer formed from a polymer solid electrolyte. Such a solid electrolytic capacitor is manufactured as follows.

[0003] First, a chemical conversion film is grown on the surface of a porous body by anodizing a porous body made of a valve metal such as tantalum, aluminum, and niobium. A solid electrolyte layer made of a solid polymer electrolyte is formed on the chemical conversion film. Subsequently, a carbon layer is formed on the surface of the solid electrolyte layer, and a paint containing silver is applied on the carbon layer to provide a cathode extraction electrode made of a silver conductive resin layer. The carbon layer joins the solid electrolyte layer and the silver conductive resin layer,
Improves conduction in the capacitor.

[0004]

However, the solid polymer electrolyte deteriorates in oxygen due to various heat treatments during the manufacturing process of the capacitor, and the conductivity decreases. Therefore, the capacitance of the solid electrolytic capacitor is reduced, and the equivalent series resistance ("Equivalent series resistance") is reduced.
There is a problem that the "stand" (hereinafter referred to as ESR) and dielectric loss increase.

The present invention has been made to solve the above-described problems, and has as its object to provide a large-capacity, low-ESR, low-loss solid electrolytic capacitor and a method of manufacturing the same.

[0006]

According to the present invention, there is provided a solid electrolytic capacitor comprising: an anode electrode body made of a valve metal; an anodic oxide film formed on the anode electrode body; and an oxygen scavenging film formed on the anodic oxide film. A solid electrolyte layer made of a polymer solid electrolyte containing a reactive metal organic complex as an additive. Since the solid electrolyte layer contains an oxygen-scavenging metal-organic complex as an additive, the oxygen-scavenging metal complex suppresses the intrusion of oxygen from the outside into the solid electrolyte layer, and oxygen moves from the pores on the surface of the solid electrolyte layer to the inside. The diffusion can be delayed with time, and an increase in the oxygen concentration around the solid electrolyte layer can be suppressed.
Therefore, since the solid electrolyte layer is prevented from being oxygen-degraded by various heat treatments during the manufacturing process of the solid electrolytic capacitor and the electric conductivity is suppressed from decreasing, a solid electrolytic capacitor having a large capacity, a low ESR, and a small dielectric loss is used. Can be provided. The above "solid electrolyte layer undergoes oxygen degradation" means that the polymer solid electrolyte contained in the solid electrolyte layer is bonded to oxygen, thereby reducing the free electrons of the polymer solid electrolyte and lowering the conductivity. Is shown.

The valve metal is aluminum, tantalum,
And at least one selected from the group consisting of niobium.

When the conductivity of the oxygen-scavenging metal-organic complex is about 1.0 × 10 ⁻⁷ S / cm or more, it is possible to prevent the decrease in conductivity due to the addition of the oxygen-scavenging metal-organic complex to the solid electrolyte layer. Can be.

When the solid electrolyte layer contains the oxygen-scavenging metal-organic complex in an amount of 0.2% by weight or more and 10% by weight or less with respect to the polymer solid electrolyte, the oxygen-scavenging metal-organic complex is added to the solid electrolyte layer. A decrease in the conductivity of the solid electrolyte layer can be prevented.

It is preferable that the oxygen-scavenging metal organic complex is a phthalocyanine metal complex.

Preferably, the metal contained in the oxygen-scavenging metal-organic complex is selected from the group consisting of iron, cobalt, copper and nickel.

Preferably, the solid polymer electrolyte is at least one polymer selected from the group consisting of pyrrole, aniline, and 3,4-ethylenedioxythiophene.

The method of manufacturing a solid electrolytic capacitor according to the present invention is characterized in that a polymer solid electrolyte containing an oxygen-scavenging metal organic complex as an additive is formed on an anodic oxide film formed by anodizing an anode electrode body made of a valve metal. Forming a solid electrolyte layer, and forming a cathode electrode layer on the solid electrolyte layer. Since the solid electrolyte layer is formed from a polymer solid electrolyte containing an oxygen-scavenging metal-organic complex as an additive, various heat treatments during the manufacturing process of the solid electrolytic capacitor cause the solid electrolyte layer to undergo oxygen degradation and lower conductivity. Is suppressed. Therefore, a solid electrolytic capacitor having a large capacity, a low ESR, and a small dielectric loss can be easily manufactured.

In the step of forming the solid electrolyte layer, it is preferable to use a polymerization liquid containing an oxygen-scavenging metal organic complex as an additive.

If at least one of the step of forming the solid electrolyte layer and the step of forming the cathode electrode layer is performed at a partial pressure of oxygen or less in the air, a decrease in the electric conductivity of the solid electrolyte layer can be further prevented.

[0016]

FIG. 1 is a schematic sectional view showing an embodiment of a solid electrolytic capacitor 100 according to the present invention.

The solid electrolytic capacitor 100 of the present invention has an anode electrode body 2 made of a valve metal, an anodic oxide film 4 (dielectric layer) formed on the anode electrode body 2, and an anodic oxide film 4 formed on the anodic oxide film 4. Solid electrolyte layer 6. The solid electrolyte layer 6 is formed from a polymer solid electrolyte containing the oxygen-scavenging metal-organic complex 12 as an additive. For example, a carbon layer 8 is formed on the solid electrolyte layer 6, and the solid electrolyte layer 6 and the cathode electrode body 10 are connected via the carbon layer 8.

The anode electrode body 2 is made of, for example, a metal having a valve action (valve metal) such as tantalum, aluminum, and niobium, or a porous sintered body made of fine particles thereof. In order to increase the effective surface area and increase the capacitance, a valve metal foil subjected to a surface treatment by etching or the like may be used as the anode electrode body 2.

The solid electrolyte layer 6 is formed of a polymer solid electrolyte containing the oxygen-scavenging metal-organic complex 12 as an additive. The polymer solid electrolyte is, for example, a polymer formed from monomers such as pyrrole, aniline, thiophene, and 3,4-ethylenedioxythiophene. The polymer may be formed by any one of chemical polymerization and electrolytic polymerization. In order to prevent a decrease in the electric conductivity of the solid electrolyte layer 6 due to the addition of the oxygen-scavenging metal-organic complex 12, the electric conductivity of the oxygen-scavenging metal-organic complex 12 is about 1.0 × 10 ^−7.
S / cm or more, and the solid electrolyte layer 6 preferably contains the oxygen-scavenging metal-organic complex 12 in an amount of 0.2% by weight or more and 10% by weight or less based on the polymer solid electrolyte.

The oxygen-scavenging metal-organic complex 12 is, for example, phthalocyanine iron (II) (conductivity: 1.0 × 10 ⁻⁷ S / c)
m), phthalocyanine cobalt (II) (conductivity 1.5 ×
Phthalocyanines such as 10 ^-7 S / cm), copper phthalocyanine (II) (conductivity 2.8 × 10 ^-7 S / cm) and nickel phthalocyanine (II) (conductivity 2.2 × 10 ^-7 S / cm) It is preferably a metal complex. The conductivity of the various materials described above was obtained as a result of molding powders of the various materials so as to have a density of 50% of the theoretical density.

The carbon layer 8 which can be formed on the solid electrolyte layer 6 is formed of, for example, carbon particles. The carbon layer 8 joins the solid electrolyte layer 6 and the cathode electrode body 10 made of a silver conductive resin layer to improve conduction in the capacitor.

Hereinafter, the solid electrolytic capacitor 100 of the present invention will be described.
Will be described.

The anode electrode body 2 made of a valve metal is anodized by a method known to those skilled in the art, and an anodic oxide film 4 as a dielectric layer is formed on the surface of the anode electrode body 2. As shown in FIG. 1, in order to increase the effective surface area, it is preferable to roughen the anode electrode body 2 by etching or the like. The anodic oxide film 4 has a hole 20 formed in the anode electrode body 2.
Is also formed.

Next, an oxygen-scavenging organic complex 1 was used as an additive.
2 is formed on the anodic oxide film 4. In the solid electrolyte layer 6,
The oxygen-scavenging organic complex 12 composed of, for example, a phthalocyanine metal complex contained as an additive does not contribute to the polymerization reaction of the solid polymer electrolyte. The oxygen-scavenging organic complex 12 is
It suppresses oxygen from entering from outside the solid electrolyte layer 6,
It functions to delay the diffusion of oxygen from the pores on the surface of the solid electrolyte layer 6 to the inside over time, thereby suppressing an increase in the oxygen concentration around the solid electrolyte layer 6.

Further, a carbon layer 8 is formed on the solid electrolyte layer 6 by a method known to those skilled in the art.

Subsequently, a cathode electrode layer 10 made of, for example, a silver conductive resin layer is formed on the carbon layer 8 by a method known to those skilled in the art, and a solid electrolytic capacitor 100 is completed.

Hereinafter, the present invention will be described more specifically with reference to examples.

Embodiment 1 Hereinafter, a method for manufacturing the solid electrolytic capacitor 100 of Embodiment 1 will be described. Made of fine tantalum powder, size 1.4 mm x 3.0 mm x 3.8 m
m, a porous sintered body (anode electrode body) 2 having a quantity of electricity of 42,000 μF · V / g per unit weight was subjected to anodic oxidation in a phosphoric acid solution at 80 ° C. while applying a voltage of 32 V to form a dielectric material. A layer (anodized film) 4 is formed.

140 g of 3,4-ethylenedioxythiophene as a monomer and p-type as an oxidizing agent and a dopant
1100 g of iron (III) toluenesulfonate and iron (II) phthalocyanine as an oxygen-scavenging metal organic complex as an additive are mixed with 800 g of 1-butanol as a solvent to prepare a polymerization solution, and kept at 4 ° C. . The weight of the phthalocyanine iron (II) to be mixed is varied to prepare seven types of polymerization liquids. The weight of the phthalocyanine iron (II) to be mixed was 0.2 g (0.1% by weight based on the weight of the obtained solid electrolyte layer) and 0.4 g (0.2% based on the weight of the obtained solid electrolyte layer). %, 1 g (0.5% by weight based on the weight of the obtained solid electrolyte layer), 4 g (2% by weight based on the weight of the obtained solid electrolyte layer), 10 g (based on the weight of the obtained solid electrolyte layer) 5% by weight), 20 g (10% by weight based on the weight of the obtained solid electrolyte layer), and 40 g (20% by weight based on the weight of the obtained solid electrolyte layer). Anodized film 4
Is immersed for 15 minutes. The porous sintered body 2 is taken out of the polymerization solution, and the ambient temperature is set to a room temperature to room temperature.
The temperature is gradually raised to 150 ° C. to vaporize 1-butanol and oxidative polymerization of 3,4-ethylenedioxythiophene. After that, the porous sintered body 2 is washed and dried. By repeating the immersion, oxidative polymerization, washing, and drying steps eight times, the solid electrolyte layer 6 is anodized.
Form on top.

Next, 120 g / carbon particles containing a 2% water-soluble acrylic binder and having a particle size of about 10 nm to 5 μm.
Prepare a liter solution. The porous sintered body 2 having the anodic oxide film 4 and the solid electrolyte layer 6 is immersed in the carbon particle solution for 3 minutes, and then dried at 120 ° C. for 30 minutes to form the carbon layer 8 on the solid electrolyte layer 6.

Further, a silver conductive resin is applied on the carbon layer 8 and dried and cured at 180 ° C. for 1 hour to provide a cathode extraction electrode (cathode electrode body) 10 made of the silver conductive resin layer.
After that, heat treatment was performed at 150 ° C. for 8 hours,
A type of solid electrolytic capacitor 100 is completed.

Example 2 In Example 2, phthalocyanine cobalt (II), phthalocyanine copper (II) and phthalocyanine nickel (II) are used as the oxygen-scavenging organic complexes as additives. Three types of solid electrolytic capacitors 100 having a solid electrolyte layer 6 in which these oxygen-scavenging organic complexes are mixed as additives are produced.

Each of the above three types of oxygen-scavenging organic complexes is added in an amount of 10 g to a polymerization solution for forming the solid electrolyte layer 6.
(5% by weight based on the weight of the obtained solid electrolyte layer 6). Three types of solid electrolytic capacitors 100 of Example 2 are completed in the same manner as in Example 1 except that a different oxygen-scavenging organic complex is used as an additive.

(Comparative Example) FIG. 2 is a schematic sectional view showing a solid electrolytic capacitor 200 of a comparative example. The solid electrolytic capacitor 200 is provided between the anode electrode body 2 made of a porous sintered body of valve metal and the cathode electrode body 10 made of a silver conductive resin layer facing the anode electrode body 2. Oxide film 4
(Dielectric layer), solid electrolyte layer 18, and carbon layer 8
Having. The solid electrolytic capacitor 200 does not include an oxygen-scavenging metal-organic complex. Members having functions substantially similar to those of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

Hereinafter, a solid electrolytic capacitor 200 of a comparative example will be described.
Will be described.

As in the above-described embodiment, a dielectric layer (anodic oxide film) 4 is formed on the surface of the porous sintered body (anode electrode body) 2.

Subsequently, 140 g of 3,4-ethylenedioxythiophene as a monomer and 1100 g of iron (III) p-toluenesulfonate as an oxidizing agent and a dopant were mixed with 800 g of 1-butanol as a solvent. 4 prepared
The porous sintered body 2 having the anodic oxide film 4 is immersed in the polymerization liquid at 15 ° C. for 15 minutes. The porous sintered body 2 is taken out of the polymerization solution, and the temperature of the atmosphere is gradually increased from room temperature to 150 ° C.
-Vaporization of butanol and oxidative polymerization of 3,4-ethylenedioxythiophene. Then, the porous sintered body 2
Is washed and dried. The solid electrolyte layer 18 is formed on the anodic oxide film 4 by repeating the steps of immersion, oxidative polymerization, washing and drying eight times.

Further, similarly to the embodiment, a cathode electrode body 10 comprising a carbon layer 8 and a silver conductive resin layer is provided to complete a solid electrolytic capacitor 200.

The solid electrolytic capacitor 100 according to the first and second embodiments and the solid electrolytic capacitor 200 according to the comparative example
The capacitance at 120 Hz and 100 kHz and the ESR at 1 MHz are shown in Table 1.

[Table 1]

Table 1 shows that the capacitance of the solid electrolytic capacitor 100 according to the embodiment of the present invention is higher than the capacitance of the solid electrolytic capacitor 200 according to the comparative example. Further, the ESR of the solid electrolytic capacitor 100 according to the embodiment of the present invention is
It can be seen that it is lower than R.

This corresponds to the solid electrolytic capacitor 10 of the embodiment.
0, the solid electrolyte layer 8 contains phthalocyanine iron (II) (oxygen trapping metal-organic complex 12) as an additive, so that the solid electrolyte layer 8 is oxygen-degraded by various heat treatments during the manufacturing process of the solid electrolytic capacitor, This is because the decrease in the electric conductivity was suppressed. The iron (II) phthalocyanine contained in the solid electrolyte layer 8 suppresses the intrusion of oxygen into the solid electrolyte layer 8 and prevents the diffusion of oxygen from the pores on the surface of the solid electrolyte layer 8 to the inside over time. And an increase in the oxygen concentration around the solid electrolyte layer 8 can be suppressed.

Further, from Table 1, it can be seen that it is more preferable that the solid electrolyte layer contains the oxygen-scavenging metal-organic complex in an amount of 0.2 to 10% by weight based on the solid polymer electrolyte. This is because it is possible to prevent a decrease in the electric conductivity of the solid electrolyte layer due to the addition of the oxygen-scavenging metal organic complex to the solid electrolyte layer.

[0043]

As described above, according to the present invention, it is possible to provide a solid electrolytic capacitor having a large capacity, a low ESR and a small dielectric loss, and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a solid electrolytic capacitor of the present invention.

FIG. 2 is a schematic sectional view showing a solid electrolytic capacitor of a comparative example.

[Explanation of symbols]

 2 Anode electrode body 4 Anodized film 6 Solid electrolyte layer 8 Carbon layer 10 Cathode electrode body 12 Oxygen scavenging metal organic complex 18 Solid electrolyte layer 100 Solid electrolytic capacitor 200 Solid electrolytic capacitor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 101/00 H01G 9/02 331G H01G 9/00 331H 9/24 A F-term (Reference) 4J002 CM021 CM051 CN061 EZ006 FD111 FD116 GQ02 4J032 BA04 BA13 BB01 BC01 BC21 CG01

Claims (10)

[Claims] 1. An anode electrode body made of a valve metal, an anodic oxide film formed on the anode electrode body, and a polymer containing an oxygen-scavenging metal organic complex as an additive so as to suppress a decrease in conductivity. A solid electrolytic capacitor comprising a solid electrolyte and a solid electrolyte layer formed on the anodic oxide film. 2. The valve metal is aluminum, tantalum,
The solid electrolytic capacitor according to claim 1, wherein the capacitor is at least one selected from the group consisting of niobium and niobium. 3. The solid electrolytic capacitor according to claim 1, wherein the conductivity of the oxygen-scavenging metal-organic complex is about 1.0 × 10 ⁻⁷ S / cm or more. 4. The solid electrolytic capacitor according to claim 1, wherein said oxygen-scavenging metal-organic complex is a phthalocyanine metal complex. 5. The solid electrolytic capacitor according to claim 1, wherein the metal contained in the oxygen-scavenging metal-organic complex is selected from the group consisting of iron, cobalt, copper and nickel. 6. The solid electrolytic capacitor according to claim 4, wherein the solid electrolyte layer contains the oxygen-scavenging metal-organic complex in an amount of 0.2% by weight or more and 10% by weight or less based on the solid polymer electrolyte. 7. The polymer solid electrolyte is at least one polymer selected from the group consisting of pyrrole, aniline, and 3,4-ethylenedioxythiophene.
The solid electrolytic capacitor according to claim 1. 8. A step of forming a solid electrolyte layer made of a polymer solid electrolyte containing an oxygen-scavenging metal organic complex as an additive on an anodic oxide film formed by anodizing an anode electrode body made of a valve metal. Forming a cathode electrode layer on the solid electrolyte layer. 9. The method for producing a solid electrolytic capacitor according to claim 8, wherein in the step of forming the solid electrolyte layer, a polymerization liquid containing the oxygen-scavenging metal-organic complex as an additive is used. 10. The solid electrolyte according to claim 1, wherein at least one of the step of forming the solid electrolyte layer and the step of forming the cathode electrode layer is performed at a partial pressure of oxygen or less in air. Manufacturing method of capacitor.