JPH11265838A - Paste composition for solid electrolyte formation, solid electrolysis capacitor using the same and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform the prescribed film thickness of a paste composition for solid electrolyte formation and to inhibit the contact resistance of manganese dioxide powder, by a method wherein the paste composition for solid electrolyte formation contains a conductive filler consisting of either of the metallic oxide powder and/or the carbon powder and a manganese nitride solution as its essential components. SOLUTION: A paste composition for solid electrolyte formation contains an electric conductivity of 1×10<2> Ω.cm and below of metallic oxide powder, such as manganese dioxide powder, ruthenium oxide powder, indium oxide powder and niobium dioxide powder, a mean particle diameter of 50 μm or below of carbon powder, such as graphite powder and carbon black powder, or a conductive filler consisting of either of the metallic oxide powder and the carbon powder, and a manganese nitride solution as its essential components. As a result, the prescribed film thickness of the paste composition can be uniformly obtained by a one-time application of the paste composition and the contact resistance of the manganese dioxide powder can be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a paste composition for forming a solid electrolyte used for forming an electrode layer on an electronic component such as a capacitor, a solid electrolytic capacitor using the same, and a method for producing the same. is there.

[0002]

2. Description of the Related Art Conventionally, a method of thermally decomposing a manganese nitrate solution has been employed for forming a solid electrolyte layer of an electronic component such as a tantalum capacitor. In other words, a sintered body made of a valve metal powder such as tantalum is used as the anode body,
The sintered body is subjected to a chemical conversion treatment to form an oxide film of Ta2O5. Next, the sintered body having the anodic oxide film formed thereon is immersed in a solution such as manganese nitrate having an arbitrary concentration, and is baked at an arbitrary temperature to be thermally decomposed into manganese dioxide or the like. After firing, the oxide film damaged by heating is repaired by a re-chemical conversion treatment. The steps of dipping, firing and re-chemical formation are repeated several times to several tens of times to form a semiconductor layer such as manganese dioxide having an arbitrary thickness. After forming the semiconductor layer, carbon,
A silver paste or the like is sequentially applied to form a cathode layer. Then, after coating, external leads are connected with solder, a conductive adhesive, or the like, and the package is covered with a resin by a resin dipping method, a resin molding method, or the like, thereby manufacturing a solid electrolytic capacitor.

[0003] In this method, the thickness of the coating film obtained at the same time is extremely small during the step of immersing the sintered body having the anodic oxide film formed therein in a manganese nitrate solution and thermally decomposing it.
In order to form a semiconductor layer having a predetermined thickness, it is necessary to repeat the thermal decomposition process several times to several tens of times, which is disadvantageous in that the time and energy cost required for the process are extremely large. As a problem in the performance of the solid electrolytic capacitor, the thickness of the semiconductor layer such as manganese dioxide is difficult to be uniform,
When the thickness is small, there is a disadvantage that the anodic oxide film directly contacts the carbon layer and the leakage current increases. In addition, when the sintered body has a square shape, the semiconductor layer such as manganese dioxide is thicker at the corners than at the other parts. There is a disadvantage that the moisture resistance is reduced. Furthermore, when the resin sheathing is performed by the resin dipping method, the dimensions are likely to vary, and stress is applied to corner portions when the resin sheathing shrinks, resulting in a disadvantage that characteristics are deteriorated.

Regarding the above problem, Japanese Patent Laid-Open Publication No.
No. 59 discloses a method of mixing manganese dioxide powder into a volatile solvent such as water, alcohol, thinner, carbon tetrachloride, and ammonium carbonate. Japanese Patent Application Laid-Open No. Hei 7-233298 discloses a method in which a part of metal powder used for a conductive paste is replaced with manganese dioxide powder. However, these methods have a problem that it is difficult to obtain a uniform coating film due to aggregation and sedimentation of the manganese dioxide powder in the solution, and the properties as a solid electrolyte are not sufficiently exhibited.

Further, Japanese Patent Application Laid-Open No. Hei 8-69559 discloses a method for obtaining a paste composition for forming a solid electrolyte in which manganese dioxide powder hardly precipitates and a uniform coating film can be formed. However, there is a problem that the coating film has unevenness and cracks. In addition, there is a problem that the equivalent series resistance ESR increases in the capacitor characteristics. This is because the manganese dioxide layer of the cured paste has a higher specific resistance than the conventional manganese dioxide layer obtained from the thermal decomposition of manganese nitrate, and the contact resistance between the manganese dioxide fillers is higher. It is thought to be due to the largeness.

[0006]

SUMMARY OF THE INVENTION The present invention overcomes the above drawbacks, enables a uniform film thickness to be obtained, suppresses the contact resistance of manganese dioxide powder, and reduces the specific resistance of the cured paste to a low level. By using the paste composition for forming a solid electrolyte capable of obtaining a resistive coating film and this composition, the equivalent series resistance characteristics, leakage current characteristics, heat resistance, moisture resistance, etc. of the solid electrolytic capacitor and the accuracy of the external dimensions are improved. An improved solid electrolytic capacitor and a method for manufacturing the same are provided.

[0007]

SUMMARY OF THE INVENTION The present invention provides a solid electrolyte comprising (A) a metal oxide powder and / or (B) a conductive filler composed of one or both of carbon powder, and (C) a manganese nitrate solution as an essential component. The present invention relates to a forming paste composition.

In the present invention, it is preferable that the binder resin (D) is an essential component.

In the present invention, it is preferable that the conductivity of the metal oxide powder (A) be 1 × 10 ² Ω · cm or less.

In the present invention, it is preferable that the average particle size of the metal oxide powder (A) is 50 μm or less.

In the present invention, it is preferable that the metal oxide powder (A) is a manganese dioxide powder containing a β-type crystal structure.

In the present invention, it is preferable to combine (A) the metal oxide powder with two or more metal oxide powders.

In the present invention, it is preferable that the average particle size of the carbon powder (B) is 50 μm or less.

In the present invention, as the coupling agent (E), one or two of silane, titanate, aluminum, zirconium, zirconium, fatty acid, carboxylic acid and phosphoric acid are used. It is preferable that the above be an essential component.

The present invention relates to a solid electrolytic capacitor using the above paste composition for forming a solid electrolyte.

The present invention relates to a method for producing a solid electrolytic capacitor using the above paste composition for forming a solid electrolyte.

In the production method of the present invention, an anodic oxide film is formed on the surface of an anode body made of a valve metal powder, a semiconductor layer is formed on the anodic oxide film, and a conductive film is further deposited thereon. In the method for manufacturing a solid electrolytic capacitor to be used as the cathode layer, it is preferable that all or a part of the semiconductor layer is a semiconductor layer made of the paste composition for forming a solid electrolyte.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a paste composition for forming a solid electrolyte, a solid electrolytic capacitor using the paste composition and a method of manufacturing the same according to the present invention will be described in detail. As the metal oxide powder (A) in the present invention, considering the electrical conductivity,
For example, manganese dioxide (including β-type crystal structure), ruthenium oxide, iridium oxide, rhenium trioxide, niobium dioxide, antimony oxide-doped tin oxide, tin oxide / antimony-doped titanium oxide and the like can be mentioned. There is no particular limitation as long as the conductivity is 1 × 10 ² Ω · cm or less. The average particle size of the metal oxide powder is 50 μm or less in consideration of the dispersion stability of the paste and the applicability.
The following are preferred. If the average particle size exceeds 50 μm, sedimentation tends to occur, and it tends to be difficult to form a uniform coating film. The shape of the metal oxide powder is exemplified by a sphere, an irregular shape, a crushed shape and the like, but is not particularly limited. Note that two or more different metal oxide powders may be used in combination.

In the present invention, the compounding amount of (A) the metal oxide powder is as follows: (A) a metal oxide powder and (B) a conductive filler made of a single or a combination of two types of carbon powder, and (C) a manganese nitrate solution. Is preferably 1 to 90 parts by weight with respect to 100 parts by weight of
It is more preferably 80 parts by weight, and further preferably 20 to 70 parts by weight. If the amount is less than 1 part by weight, it is difficult to form a coating film, and the function as a solid electrolyte tends to decrease. If the amount exceeds 90 parts by weight, the applicability as a paste and the adhesion to a base material decrease. Tend.

The carbon powder (B) in the present invention includes, for example, graphite, carbon black and the like, but is not particularly limited as long as it is a conductive carbon powder. The average particle diameter of the carbon powder is preferably 50 μm or less, more preferably 10 μm or less, in consideration of paste coatability and the like.
If the average particle size exceeds 50 μm, the dispersion state is unstable, and further, there is a tendency that peeling and cracking occur from the base material during the formation of the coating film, making it difficult to form a uniform coating film. Also, the shape of the carbon powder is spherical, scale-like,
Examples include, but are not particularly limited to, irregular shapes. Note that two or more different carbon powders may be used in combination.

In the present invention, the compounding amount of the (B) carbon powder is as follows.
In addition, the amount is preferably 90 parts by weight or less, more preferably 80 parts by weight or less, and even more preferably 70 parts by weight or less, based on 100 parts by weight of the total amount of the manganese nitrate solution (C). If the amount exceeds 90 parts by weight, the applicability as a paste and the adhesion to a substrate tend to decrease.

In the present invention, as the conductive filler of the metal oxide powder (A) and the carbon powder (B) alone or in combination of two kinds, one kind of metal oxide powder,
Two or more kinds of metal oxide powders, one kind of carbon powder, two or more kinds of carbon powders, one kind of metal oxide powder and one kind of carbon powder, two or more kinds of metal oxide powders and one kind of carbon powder And one type of metal oxide powder and two or more types of carbon powder, and two or more types of metal oxide powder and two or more types of carbon powder. The amount used when combining (A) metal oxide powder and (B) carbon powder is based on 100 parts by weight of the total amount of (A) metal oxide powder, (B) carbon powder and (C) manganese nitrate solution.
The amount is preferably 1 to 90 parts by weight, and the metal oxide powder (A) and the carbon powder (B) are selected in any ratio.

The manganese nitrate solution (C) used in the present invention includes, for example, an aqueous solution of manganese nitrate, but is not particularly limited as long as it is a solution in which manganese nitrate is dissolved. In the present invention, the compounding amount of the (C) manganese nitrate solution is 100% by weight of the conductive filler of (A) the metal oxide powder and the (B) carbon powder alone or in combination of two kinds, and (C) the manganese nitrate solution. Parts by weight, preferably 10 to 95 parts by weight, more preferably 20 to 9 parts by weight.
It is more preferably 0 parts by weight, and further preferably 25 to 80 parts by weight. If the amount is less than 10 parts by weight, the dispersion of the metal oxide powder (A) and the carbon powder (B) becomes insufficient, and if it exceeds 95 parts by weight, a sufficient film thickness tends not to be obtained at once. .

In the present invention, the use of the binder resin (D) is effective for improving the strength and adhesion of the coating film.
(D) As the binder resin, a thermosetting resin, a thermoplastic resin, or a resin mixture thereof is used. For example, urea resin, urea / melamine resin, phenol resin, epoxy resin, polyester resin, alkyd resin,
Urethane resin, polyethylene resin, polypropylene resin, polyacetal resin, acrylic resin, sialyl phthalate resin, polystyrene resin, silicon resin, fluorine resin, polyvinyl chloride resin, polyvinyl resin, polyamide resin, polyetheramide resin, polyetheramideimide resin and Water-soluble polymer resins and the like can be mentioned. Note that two or more resins may be used in combination.

In the present invention, the compounding amount of the binder resin (D) is based on the total amount of the (A) metal oxide powder and the (B) carbon powder alone or in combination of two conductive fillers, and (C) the manganese nitrate solution. It is preferable that the content is not more than 40 parts by weight based on 100 parts by weight.
More preferably, the amount is not more than part by weight. This formula is 4
If the amount exceeds 0 parts by weight, the conductivity tends to decrease, and the performance as a solid electrolyte tends to deteriorate.

In the present invention, the use of the coupling agent (E) prevents aggregation of the (A) metal oxide powder and (B) the carbon powder and is effective in stabilizing the dispersion. As a method of using the coupling agent (E), a method of directly adding to the paste for forming a solid electrolyte and using it, or a method of treating (A) a metal oxide powder and (B) a carbon powder with a coupling agent (E). The method used is mentioned. As a method for treating (A) the metal oxide powder, for example, a method in which (E) a coupling agent is directly added to the (A) metal oxide powder and mixed by stirring (dry treatment method) or a solvent such as hexane or toluene is used. (E) The coupling agent is dissolved in advance, and the metal oxide powder (A) is added therein, mixed and stirred, and then the solvent is removed and dried (wet processing method).
The same method can be used for the carbon powder (B).

The coupling agent (E) in the present invention is not particularly limited as long as it can prevent aggregation of the (A) metal oxide powder and (B) the carbon powder and improve the dispersion stability. Preferred examples thereof include silane-based, titanate-based, aluminum-based, zirconium-based, zirconium-based, fatty acid-based, carboxylic acid-based, and phosphoric acid-based coupling agents. In the present invention, the amount of the coupling agent (E) added is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, based on 100 parts by weight of the total amount of the (A) metal oxide powder and (B) the carbon powder. If the amount of the coupling agent (E) exceeds 10 parts by weight, the electrical conductivity of the metal oxide powder (A) and the electrical conductivity of the carbon powder (B) tend to decrease.

The paste composition for forming a solid electrolyte of the present invention has, for example, an antioxidant, a chelating agent, a surfactant and other various functions as long as it does not adversely affect the properties of the cured product when the paste and the coating film are formed. Additives and modifiers may be added.

The paste composition for forming a solid electrolyte of the present invention comprises a predetermined amount of (A) a metal oxide powder, (B) a conductive filler made of a single or a combination of two carbon powders, (C) a manganese nitrate solution and the like. Can be easily obtained by kneading or dispersing uniformly using a conventional stirrer, mill, three-roll or roll mill, etc., without changing the characteristics as a solid electrolyte, uniform and thick in one application. It can provide a coating film and can be suitably used as a solid electrolyte layer of a tantalum capacitor or the like.

The present invention relates to a solid electrolytic capacitor using a paste composition for forming a solid electrolyte, a method for producing the same, an anodic oxide film formed on the surface of an anode body made of valve metal powder, and a semiconductor layer formed on the anodic oxide film. And a method for producing a solid electrolytic capacitor having a cathode layer by further attaching a conductive film thereon, wherein a solid electrolytic capacitor in which part or all of a semiconductor layer is replaced with the solid electrolyte forming paste composition of the present invention. , A method for manufacturing a solid electrolytic capacitor for forming a semiconductor layer by combining a semiconductor mother liquor and the paste composition for forming a solid electrolyte of the present invention, and a paste for forming a solid electrolyte of the present invention on the outermost shell of the semiconductor layer. The present invention relates to a method for producing a solid electrolytic capacitor using the composition. The manufacturing method is not particularly limited as long as the solid electrolyte-forming paste composition of the present invention is included in a part of the semiconductor layer. For example, after forming an anodized film on the surface of the anode body made of a valve action metal powder, or after immersing the sintered body having the formed anodized film in a semiconductor mother liquor, firing and re-forming, the present invention A semiconductor layer is formed using the paste composition for forming a solid electrolyte. Next, if necessary, the molded body is immersed in a semiconductor mother liquor, fired and re-formed to form a semiconductor layer, and a solid electrolytic capacitor is manufactured.

More specifically, a preferred manufacturing method will be described. One end of a tantalum lead wire or the like is buried in a valve metal such as tantalum, compression molded by a press, and heated in a vacuum at a temperature of about 2000 ° C. for several tens of minutes. To form a tantalum sintered body. Then, one end of the tantalum lead wire or the like of the sintered body was welded to a metal bar such as stainless steel, and chemical conversion treatment by applying a voltage to the sintered body by chemical liquid such as nitric acid or phosphoric acid, Ta ₂ O ₅
Is formed. After forming the anodic oxide coating,
The sintered body is dipped in the paste composition for forming a solid electrolyte of the present invention for several seconds, fired and re-formed to form a semiconductor layer mainly composed of manganese dioxide or the like. Alternatively, a sintered body having an anodic oxide film formed thereon is immersed in a semiconductor mother liquor such as a manganese nitrate solution, baked at a temperature of 200 ° C. to 350 ° C., and thermally decomposed to form a semiconductor mainly containing manganese dioxide or the like inside the sintered body. Form a layer. After firing, the anodized film damaged by heating is repaired by re-chemical formation. Then, the above immersion, firing and re-chemical conversion steps are repeated several times as necessary. Next, the sintered body is immersed in the paste composition for forming a solid electrolyte of the present invention for several seconds, fired and re-formed to form a semiconductor layer mainly composed of manganese dioxide or the like. Specifically, the sintered body is immersed in the paste composition for forming a solid electrolyte of the present invention for several seconds, and then fired at a temperature of 200 to 350 ° C. to form a semiconductor layer mainly containing manganese dioxide or the like. . After firing, the damaged anodic oxide film is repaired by re-chemical conversion. The immersion, firing and re-chemical conversion steps may be repeated twice or more in order to obtain a semiconductor layer having a sufficient thickness. Then, if necessary, the molded body is immersed in a semiconductor mother liquor such as a manganese nitrate solution, baked at a temperature of 200 ° C. to 350 ° C., thermally decomposed, and further re-formed to mainly produce manganese dioxide and the like. Is formed.

In the above-described semiconductor layer forming process, the solid electrolyte forming paste composition of the present invention is used alone or in combination with a semiconductor mother liquor. The combination is not particularly limited as long as it is included in the section. After forming the semiconductor layer by the above method, carbon, silver paste and the like are sequentially applied to form a cathode layer. Next, this formed body is connected to a lead frame with solder or a conductive adhesive, and an anode,
In a state where the cathode and the like can be taken out, a resin exterior is formed by a resin dipping method or a resin molding method.

[0033]

Next, the present invention will be described specifically with reference to examples, but the present invention is not limited by these examples.

Example 1 As a conductive filler, manganese dioxide powder (RB-A made by Mitsui Kinzoku) was heat-treated at 450 ° C. for 1.5 hours. : 2 μm) 100 parts by weight, and 200 parts by weight of manganese nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) were premixed in a mortar, and then mixed.
The mixture was kneaded with this roll to obtain a paste composition for forming a solid electrolyte. Table 1 shows the results of measuring the volume resistivity, dispersibility, coating film thickness, and coatability of the paste composition for forming a solid electrolyte. Volume resistivity is about 50 by screen printing.
A μm coating film was formed on a ceramic plate, and after curing was measured and calculated by a four-terminal method using a digital multimeter.
The dispersibility was measured using a grain gauge according to the method of JIS-K5400. For measuring the coating thickness, a 1 × 2 cm ceramic plate was dipped in the paste for about 3 seconds and then pulled up.
After firing at 250 ° C. for 10 minutes, the measurement was performed using a micrometer. In addition, the applicability was evaluated by visually observing the surface of the coating film after drying, and evaluated from three grades of excellent (◎), good (○), and poor (×) in terms of good surface condition (in the following examples). The same).

Example 2 As a conductive filler, ruthenium oxide 1 of a metal oxide was used.
The same experiment as in Example 1 was conducted except that 00 parts by weight was used. Table 1 shows the volume resistivity, dispersibility, coating film thickness, and coatability of the obtained paste composition for forming a solid electrolyte.

Example 3 The same experiment as in Example 1 was carried out except that 50 parts by weight of carbon powder (Hitasol GP-60S manufactured by Hitachi Powdered Metals Co., Ltd.) was used as the conductive filler, and the obtained paste for forming a solid electrolyte was obtained. Table 1 shows the volume resistivity, dispersibility, coating film thickness and coatability of the composition.

Example 4 An experiment similar to that of Example 1 except that 50 parts by weight of manganese dioxide powder (RB-A) having a β-type crystal structure and 50 parts by weight of ruthenium oxide as a metal oxide were used as conductive fillers. Table 1 shows the volume resistivity, dispersibility, coating film thickness, and coatability of the obtained paste composition for forming a solid electrolyte.

Example 5 As a conductive filler, 80 parts by weight of manganese dioxide powder (RB-A) having a β-type crystal structure, carbon powder (HITA)
SOL GP-60S) An experiment was conducted in the same manner as in Example 1 except that 20 parts by weight was used, and the volume resistivity, dispersibility, coating film thickness and coatability of the obtained paste composition for forming a solid electrolyte were shown in Table 1. Shown in

Example 6 As a conductive filler, 40 parts by weight of manganese dioxide powder (RB-A) having a β-type crystal structure, 40 parts by weight of ruthenium oxide as a metal oxide, and carbon powder (HITASOLGP-60S)
The same experiment as in Example 1 was conducted except that 20 parts by weight was used. Table 1 shows the volume resistivity, dispersibility, coating film thickness, and coatability of the obtained paste composition for forming a solid electrolyte.

Example 7 Metal oxide ruthenium oxide 5 was used as a conductive filler.
The same experiment as in Example 1 was performed except that 0 parts by weight and 50 parts by weight of iridium oxide were used, and the volume resistivity, dispersibility, coating film thickness, and coating properties of the obtained paste composition for forming a solid electrolyte were shown. It is shown in FIG.

Example 8 As a conductive filler, ruthenium oxide 8 of a metal oxide was used.
The same experiment as in Example 1 was conducted except that 0 parts by weight and 20 parts by weight of carbon powder (HITASOL GP-60S) were used, and the volume resistivity, dispersibility, and coating film of the obtained solid electrolyte-forming paste composition were obtained. Table 1 shows the thickness and coatability.

Comparative Example 1 The same experiment as in Example 1 was carried out except that 100 parts by weight of manganese dioxide powder containing no β-type crystal structure (γ-type crystal structure) was used as the conductive filler. Table 1 shows the volume resistivity, dispersibility, coating film thickness, and coatability of the forming paste composition.

Comparative Example 2 Example 1 was repeated except that 100 parts by weight of a metal oxide having a conductivity of 1 × 10 ² Ω · cm or more was used as the conductive filler.
Table 1 shows the volume resistivity, dispersibility, coating film thickness, and coatability of the obtained paste composition for forming a solid electrolyte.

Comparative Example 3 The same experiment as in Example 1 was carried out except that manganese dioxide powder having an average particle size larger than 50 μm was used as the conductive filler, and the volume resistivity of the obtained paste composition for forming a solid electrolyte was obtained. The dispersibility, coating thickness and coatability are shown in Table 1.

Comparative Example 4 The same experiment as in Example 1 was carried out except that ruthenium oxide having an average particle size larger than 50 μm was used as the conductive filler, and the volume resistivity of the obtained paste composition for forming a solid electrolyte was as follows: Table 1 shows the dispersibility, coating film thickness, and coatability.

Comparative Example 5 The same experiment as in Example 1 was carried out except that carbon powder having an average particle diameter of more than 50 μm was used as the conductive filler, and the volume resistivity of the obtained paste composition for forming a solid electrolyte was Table 1 shows the dispersibility, coating film thickness, and coatability.

From the results shown in Table 1, it was found that the paste composition for forming a solid electrolyte of the present invention had good dispersibility, low volume resistivity, and was able to obtain an appropriate coating thickness by one application. did. In particular, by adding tens of percent of carbon powder, the volume resistivity is reduced, and it is expected that the equivalent series resistance ESR characteristics of the capacitor will be reduced.

Next, a method for producing a solid electrolytic capacitor using the paste composition for forming a solid electrolyte of the present invention will be specifically described with reference to Examples and Comparative Examples. It is not particularly limited as long as the electrolyte-forming paste composition is included.

Example 9 First, one end of a 0.24φ tantalum lead wire was buried in fine tantalum powder and pressed to obtain 1.97 mm × 2.1 mm ×
A 2.8 mm square compact is produced and sintered. This sintered body was subjected to a chemical conversion treatment with nitric acid to form an anodic oxide film of Ta ₂ O ₅ . Next, the paste composition for forming a solid electrolyte prepared in Example 1 was used as a stock solution, and diluted with manganese nitrate hexahydrate into a stock solution: manganese nitrate hexahydrate = 3: 2 (weight ratio). Was immersed for several seconds, baked at 250 ° C. for 10 minutes, and further subjected to a chemical conversion treatment. And this dipping,
The firing and the chemical conversion treatment were repeated six times to form a semiconductor layer. Next, a carbon paste and a silver paste were sequentially applied to form a cathode layer. After the formation of the cathode layer, the molded body was connected to a lead frame, and a resin exterior was formed by a resin molding method to produce a solid electrolytic capacitor.

Example 10 A solid electrolytic capacitor was manufactured in the same manner as in Example 9, except that the paste composition for forming a solid electrolyte prepared in Example 2 was used as a stock solution when forming a semiconductor layer.

Example 11 A solid electrolytic capacitor was manufactured in the same manner as in Example 9, except that the paste composition for forming a solid electrolyte prepared in Example 3 was used as a stock solution when forming a semiconductor layer.

Example 12 A solid electrolytic capacitor was manufactured in the same manner as in Example 9 except that the paste for solid electrolyte formation prepared in Example 4 was used as a stock solution when forming a semiconductor layer.

Example 13 A solid electrolytic capacitor was manufactured in the same manner as in Example 9, except that the paste composition for forming a solid electrolyte prepared in Example 5 was used as a stock solution when forming a semiconductor layer.

Example 14 A solid electrolytic capacitor was manufactured in the same manner as in Example 9 except that the paste composition for forming a solid electrolyte prepared in Example 6 was used as a stock solution when forming a semiconductor layer.

Example 15 A solid electrolytic capacitor was manufactured in the same manner as in Example 9, except that the paste composition for forming a solid electrolyte prepared in Example 7 was used as a stock solution when forming a semiconductor layer.

Example 16 A solid electrolytic capacitor was manufactured in the same manner as in Example 9 except that the paste composition for forming a solid electrolyte prepared in Example 8 was used as a stock solution when forming a semiconductor layer.

Example 17 In forming a semiconductor layer, a series of steps of immersing the sintered body having the anodic oxide film formed therein in a manganese nitrate solution, firing and re-forming was repeated three times. Next, using the paste composition for forming a solid electrolyte prepared in Example 5 as a stock solution, manganese nitrate hexahydrate was used as a stock solution: stock solution: manganese nitrate hexahydrate =
The sintered body was immersed in a liquid diluted to 3: 2 (weight ratio) for several seconds, baked at 250 ° C. for 10 minutes, and further subjected to a chemical conversion treatment. Then, a solid electrolytic capacitor was produced in the same manner as in Example 9, except that the immersion, firing and chemical conversion treatments were repeated three times.

Example 18 In forming a semiconductor layer, the paste composition for forming a solid electrolyte prepared in Example 5 was used as a stock solution of a sintered body having an anodized film formed thereon, and manganese nitrate hexahydrate was used as a stock solution: nitric acid. The sintered body was immersed in a liquid diluted to manganese hexahydrate = 3: 2 (weight ratio) for several seconds, baked at 250 ° C. for 10 minutes, and further subjected to a chemical conversion treatment. The immersion, firing and chemical conversion treatments were repeated three times. Next, a solid electrolytic capacitor was produced in the same manner as in Example 9, except that a series of treatments of dipping in a manganese nitrate solution, firing and re-chemical formation was repeated three times.

Example 19 In forming a semiconductor layer, a series of processes of immersing the sintered body having the anodized film formed therein in a manganese nitrate solution, firing and re-forming was repeated twice. Then, the paste composition for forming a solid electrolyte prepared in Example 5 was used as a stock solution, and the solution was diluted with manganese nitrate hexahydrate to a stock solution: manganese nitrate hexahydrate = 3: 2 (weight ratio). The sintered body was immersed for several seconds, fired at 250 ° C. for 10 minutes, and further subjected to a chemical conversion treatment. The immersion, firing and chemical conversion treatments were repeated twice. Next, a solid electrolytic capacitor was produced in the same manner as in Example 9, except that a series of treatments of immersing in a manganese nitrate solution, firing and re-chemical formation was repeated twice.

Comparative Example 6 The procedure of Example 9 was repeated, except that a series of steps of immersing the sintered body having the anodic oxide film formed thereon in a manganese nitrate solution, sintering and re-chemical formation was repeated six times. To produce a solid electrolytic capacitor.

Table 2 shows the results of evaluating the characteristics of the tantalum chip type solid electrolytic capacitors having a rated voltage of 16 V and 35 μF produced in Examples 9 to 19 and Comparative Example 6. Here, the number of samples was 500 each. As is clear from Table 2, in Comparative Example 6 of the conventional method, the thermal decomposition step of manganese nitrate was performed six times, but the leakage current characteristics were insufficient. However, by using the method of the present invention, as compared with Comparative Example 6, the same or higher characteristics can be obtained in the capacitance and the equivalent series resistance ESR and the characteristics of about 1/2 in the leakage current can be obtained in six application times. I was able to. Thereby, by replacing the immersion of the manganese nitrate solution and the thermal decomposition step with the immersion of the paste composition for forming a solid electrolyte of the present invention and the firing step, the number of steps can be reduced and a solid electrolytic capacitor having good characteristics can be manufactured. It became clear that there was.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

The paste composition for forming a solid electrolyte according to the present invention is excellent in conductivity and can obtain a predetermined film thickness by a single application, so that it can be used for forming a solid electrolyte layer of a tantalum capacitor element. It is suitable. According to the second aspect of the present invention, a coating film having improved strength and adhesion can be formed by adding a binder resin. According to the third aspect of the present invention, it is possible to form a low-resistance coating film by limiting the conductivity of the metal oxide powder. According to the fourth aspect of the invention, by limiting the average particle size of the metal oxide powder, sedimentation of the metal oxide powder can be suppressed, and a uniform coating film can be formed. According to the fifth aspect of the present invention, by using a manganese dioxide powder having a β-type crystal structure as the metal oxide powder, it is possible to form a semiconductor layer having the same conductivity as the conventional one. According to the invention of claim 6, by using two or more kinds of metal oxide powders, semiconductor layers having different conductivity can be formed. According to the seventh aspect of the present invention, by limiting the average particle size of the carbon powder, the sedimentation of the carbon powder can be suppressed, and a uniform coating film can be formed. Claim 8
According to the invention described above, the effects of the composition according to claim 1 are exhibited, aggregation of the metal oxide powder and the carbon powder can be prevented, and stability during use can be improved.

According to the ninth aspect of the present invention, by using the paste composition for forming a solid electrolyte of the present invention, the film quality of the semiconductor layer is made uniform, and the equivalent series resistance characteristics, leakage current characteristics, heat resistance, A solid electrolytic capacitor having improved moisture resistance and external dimension accuracy is provided. According to the tenth aspect of the present invention, by using the paste composition for forming a solid electrolyte of the present invention, the manufacturing process is simplified, the film quality of the semiconductor layer is made uniform, the equivalent series resistance characteristic and the leakage current characteristic of the capacitor are obtained. The present invention provides a method for manufacturing a solid electrolytic capacitor having improved heat resistance, moisture resistance, and external dimension accuracy. According to the eleventh aspect of the present invention, an anodic oxide film is formed on the surface of an anode body made of a valve action metal powder, a semiconductor layer is formed on the anodic oxide film, and a conductive film is further deposited thereon. In the method for manufacturing a solid electrolytic capacitor having a negative electrode layer, the equivalent series resistance characteristics of the capacitor and the leakage current are determined by the method for manufacturing a solid electrolytic capacitor in which part or all of the semiconductor layer is replaced with the solid electrolyte forming paste composition of the present invention. A solid electrolytic capacitor having improved characteristics, heat resistance, moisture resistance and accuracy of external dimensions can be manufactured.

Claims (11)

[Claims] 1. A conductive filler comprising (A) a metal oxide powder and / or (B) a carbon powder,
And (C) a paste composition for forming a solid electrolyte comprising a manganese nitrate solution as an essential component. 2. The paste composition for forming a solid electrolyte according to claim 1, further comprising (D) a binder resin as an essential component. 3. The method according to claim 2, wherein the metal oxide powder has a conductivity of 1 × 1.
3. The paste composition for forming a solid electrolyte according to claim 1, wherein the paste composition has a resistivity of 0 ² Ω · cm or less. (A) a metal oxide powder having an average particle size of 50
The paste composition for forming a solid electrolyte according to any one of claims 1 to 3, which has a diameter of not more than μm. 5. The paste composition for forming a solid electrolyte according to claim 1, wherein the metal oxide powder is a manganese dioxide powder having a β-type crystal structure. 6. The paste composition for forming a solid electrolyte according to claim 1, wherein (A) two or more metal oxide powders are combined with the metal oxide powder. 7. (B) The carbon powder has an average particle size of 50 μm.
The paste composition for forming a solid electrolyte according to any one of claims 1 to 6, which is not more than m. 8. A coupling agent (E) comprising one or more of silane, titanate, aluminum, zirconium, zirconium, fatty acid, carboxylic acid and phosphoric acid. The paste composition for forming a solid electrolyte according to any one of claims 1 to 7, which is an essential component. 9. A solid electrolytic capacitor using the paste composition for forming a solid electrolyte according to claim 1. Description: 10. A method for producing a solid electrolytic capacitor, comprising using the paste composition for forming a solid electrolyte according to claim 1. Description: 11. An anodic oxide film is formed on the surface of an anode body made of a valve metal powder, a semiconductor layer is formed on the anodic oxide film, and a conductive film is further deposited thereon to form a cathode layer. A method for producing a solid electrolytic capacitor, wherein the whole or a part of the semiconductor layer is a semiconductor layer using the paste composition for forming a solid electrolyte according to any one of claims 1 to 8.