JPH10326521A - Paste composition for forming solid electrolyte, and manufacture of electronic part using this paste composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold heat resistance and moisture resistance equal to those of manganese dioxide, and to hold the electrical characteristic equal to that of conductive high polymer, by including metal oxide powder and conductive high molecule and a solvent. SOLUTION: As a metal oxide powder, powder of manganese dioxide and lead dioxide having a characteristic of a semiconductor, which shows an electrical conductivity of 10<-5> s.cm<-1> -10 s.cm<-1> , is used. Powder of manganese dioxide or lead dioxide is blended at 1-90 pts.wt. in relation to 100 pts.wt as a total of the metal oxide powder, conductive high molecule and the solvent. As a solvent, a solvent such as cresol and toluene, which can melt or stabilize the conductive high polymer and while which can hold distribution stability of the metal oxide powder, is selected. Even and thick coating film can be obtained by one coating work without changing characteristic of the solid electrolyte by evenly kneading or distributing the predetermined quantity of metal oxide powder, conductive high polymer and the solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a method of thermally decomposing a manganese nitrate solution has been adopted for forming a solid electrolyte of an electronic component such as a tantalum capacitor. That is, using a sintered body made of a valve metal powder such as tantalum as an anode body, the sintered body is subjected to a chemical conversion treatment to form an oxide film of Ta ₂ O ₅ . Next, the sintered body after chemical conversion is immersed in an aqueous solution of manganese nitrate or the like at an arbitrary concentration, and is calcined at an arbitrary temperature to thermally decompose manganese nitrate into manganese dioxide or the like. Further, after firing, a re-chemical conversion treatment is performed to repair the oxide film damaged by heating. Then, the steps of immersion, firing and re-chemical formation are repeated several times to several tens of times to form a manganese dioxide layer or the like having an arbitrary thickness. After forming a manganese dioxide layer and the like, carbon, silver paste and the like are sequentially applied to form a cathode layer. Then, a manufacturing method is employed in which external leads are soldered after the application, and the resin is packaged by a resin dipping method, a resin molding method, or the like.

[0003] Recently, there is an example in which a conductive polymer is used as a solid electrolyte layer instead of a manganese dioxide layer.
In this case, instead of thermally decomposing manganese nitrate, a conductive polymer such as polypyrrole or polyaniline is formed or coated directly on the surface of a sintered body of a valve metal such as tantalum powder by chemical oxidative polymerization. Used as an electrolyte. Also in this case, it is necessary to repeat the formation process several to several tens of times to form the solid electrolyte layer. afterwards,
A cathode layer is formed by sequentially applying carbon, silver paste, and the like. After forming the cathode layer, solder the external leads and package the resin with resin dipping, resin molding, etc.

[Problems to be solved by the invention]

[0004] Two types of methods, namely, a method using manganese dioxide and a method using a conductive polymer are mainly used for forming a solid electrolyte for electronic parts such as tantalum capacitors.

[0005] When manganese dioxide is used as a solid electrolyte, a method of thermally decomposing manganese nitrate is used as a method of forming manganese dioxide. In a method of forming a manganese dioxide layer, a valve electrolyte metal sintered body is immersed in an aqueous solution of manganese nitrate, and then a solid electrolyte layer is formed by repeating a thermal decomposition process called a chemical conversion treatment. At that time, since the thermal decomposition of manganese nitrate, to generate NO _x in pyrolysis process, there are environmental problems such processing these cracked gas.

On the other hand, when a conductive polymer is used as a solid electrolyte, a valve-acting metal sintered body is immersed in a monomer forming the conductive polymer, and the surface of the sintered body is directly subjected to chemical oxidation polymerization by chemical oxidation polymerization. There is a method of forming a molecular layer, and a method of forming a conductive polymer layer by immersing in a previously polymerized conductive polymer solution, doping and then drying. In any of these formations of the inorganic or organic solid electrolyte layer, since the thickness of the coating film that can be formed at a time is extremely thin, a pyrolysis step, a polymerization step, or a polymerization step is performed to form an electrolyte layer having a predetermined thickness. It is necessary to repeat the immersion process several times to more than ten times,
It has the disadvantage that the energy cost and time required for it are very large. Another problem with the performance of solid electrolytic capacitors is that when a manganese dioxide layer is formed, it is difficult for the thickness to be uniform, and when the thickness is small, the carbon layer directly contacts the oxide film and the leakage current increases. There is a disadvantage that it is easy to do. In addition, when the sintered body is square, the manganese dioxide layer and the like are thicker at the corners than at the other parts. However, there is a disadvantage in that In addition, there is a disadvantage that when the resin sheathing is performed by the resin dipping method, the dimensions tend to vary, and stress is applied to the corners when the resin sheath shrinks, and the characteristics are likely to deteriorate.

On the other hand, when a conductive polymer is used as a solid electrolyte instead of manganese dioxide, the conductive polymer is an organic substance, and therefore has poorer heat resistance than manganese dioxide. When the solder is dipped, problems such as deterioration of tan δ and increase in leak current occur. In addition, since the conductivity of the conductive polymer is deteriorated by absorbing moisture, there is a problem in terms of moisture resistance.

[0008] Regarding the above problems, Japanese Patent Laid-Open No. 7-192
No. 536 discloses a method of forming a composite conductive layer containing a conductive polymer and a manganese oxide on a film. However, in this method, since a conductive layer is formed on the film by a chemical reaction, solid When applied as an electrolyte layer, there is a problem that a coating film cannot be formed thick at a time and the process cannot be simplified. Further, Japanese Unexamined Patent Publication No.
Japanese Patent No. 41338 discloses a method of using polyaniline as a conductive polymer, using polysulfonic acid having two or more sulfonic acid groups in the same molecule as a dopant in order to improve moisture resistance, As disclosed in Japanese Patent No. 59599, there is disclosed a method of using a novel disulfonate compound as a dopant in order to improve the heat resistance and moisture resistance reliability of a conductive polymer. In each case, only the conductive material is used, and it is difficult to obtain the same properties as those using manganese dioxide in terms of heat resistance and moisture resistance.

The present invention compensates for the above-mentioned drawbacks, has the same heat resistance and moisture resistance as manganese dioxide, can form a solid electrolyte layer having the same electrical properties as a conductive polymer, and has a solid electrolyte. A paste composition for forming a solid electrolyte capable of forming a thick coating and forming a uniform coating film at the time of formation, and a method for manufacturing an electronic component using the composition, that is, shortening the manufacturing time and improving leakage current characteristics, heat resistance, and moisture resistance An object of the present invention is to provide a method for manufacturing an electronic component having a solid electrolyte layer with improved properties and external dimensions.

[0010]

According to the present invention, there is provided a paste composition for forming a solid electrolyte comprising (A) a metal oxide powder, (B) a conductive polymer and (C) a solvent. The present invention relates to a method for manufacturing an electronic component. The invention according to claim 2 provides the paste composition for forming a solid electrolyte layer, which has the effects of the composition according to claim 1, can further improve the uniformity of the coating film, and is excellent in stability during use. Is what you do. The invention according to claim 3 is, in addition to the invention according to claim 2,
An object of the present invention is to provide a paste composition for forming a solid electrolyte capable of improving the uniformity of a coating film by limiting the particle diameter of a metal oxide powder and producing a coating film having a uniform film quality.
According to a fourth aspect of the present invention, there is provided a method for manufacturing an electronic component, wherein the paste for forming a solid electrolyte according to the first, second or third aspect is applied to various electronic components and dried.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a paste composition for forming a solid electrolyte according to the present invention and a method for manufacturing a solid electrolytic capacitor using the paste composition will be described in detail. The present invention relates to a paste composition for forming a solid electrolyte, comprising (A) a metal oxide powder, (B) a conductive polymer, and (C) a solvent. The metal oxide powder (A) in the present invention is preferably 10 ⁻⁵ s · cm ^{−1 to} 10 s · cm ^−1.
Powder having the properties of a semiconductor showing the electrical conductivity of manganese dioxide, lead dioxide, tin dioxide, tungsten dioxide, titanium dioxide, zinc monoxide,
Copper monoxide, nickel monoxide, cobalt monoxide, iron sesquioxide, vanadium sesquioxide, tungsten trioxide, tantalum oxide, barium titanate, etc. are included, but in consideration of conductivity, manganese dioxide, lead dioxide, zinc monoxide Is preferred. The average particle diameter of the metal oxide powder is preferably 0.01 μm to 5 μm in consideration of the conductivity and the applicability of the paste.
The one having a thickness of 0 μm is preferred, and the one having a thickness of 0.01 to 10 μm is preferred. The shape of the metal oxide powder is spherical, amorphous,
Examples include crushed shapes, but are not limited thereto. The compounding amount of the metal oxide powder in the present invention,
The amount is preferably from 1 to 90 parts by weight, more preferably from 5 to 80 parts by weight, based on 100 parts by weight of the total of (A) metal oxide powder, (B) conductive polymer and (C) solvent. Preferably, it is particularly 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 substrate tend to decrease.

The conductive polymer (B) used in the present invention preferably contains at least one kind of pyrrole, aniline, thiophene or a derivative thereof in the molecule.
Polyaniline is exemplified as being more preferred. These conductive polymers are polymerized by dissolving a polymer synthesized in advance in a solvent, or by chemically oxidizing polymerization of manganese dioxide powder on the surface of manganese dioxide powder with the monomer and metal oxide powder dispersed in the solvent. Can be used to form a polymer, but any of these methods can be used. Further, the present invention is not limited to these methods. These conductive polymers are used in combination with a dopant to impart conductivity and heat resistance. Although the kind of the dopant is not particularly limited, benzenesulfonic acid, toluenesulfonic acid, phenolsulfonic acid, phenoldisulfonic acid, sulfosuccinic acid, and derivatives thereof are exemplified in consideration of conductivity and heat resistance. The amount of the conductive polymer (B) in the present invention is (A) a metal oxide powder,
Total amount of (B) conductive polymer resin and (C) solvent 100
It is preferably 0.5 to 60 parts by weight, more preferably 1 to 50 parts by weight, and more preferably 2 to 4 parts by weight.
It is particularly preferable to use 0 parts by weight. When the blending amount is 0.
If the amount is less than 5 parts by weight, the dispersion of the metal oxide powder becomes insufficient, and a stable coating film cannot be obtained. On the other hand, when the amount exceeds 60 parts by weight, the amount of metal oxide powder attached decreases, and thick coating cannot be performed.

The solvent (C) in the present invention is not particularly limited as long as it can dissolve or stabilize the conductive polymer and maintain the dispersion stability of the metal oxide powder. Organic solvents such as N-methylpyrrolidone are exemplified as preferred. The compounding amount of the solvent (C) in the present invention is preferably 10 to 95 parts by weight based on 100 parts by weight of the total amount of the (A) metal oxide powder (B) conductive polymer and the solvent (C). 2
More preferably 0 to 90 parts by weight, 25 to 80 parts by weight
It is particularly preferred to use parts by weight. This blending amount is 10
If the amount is less than 95 parts by weight, the dispersion of the metal oxide powder becomes insufficient. If the amount exceeds 95 parts by weight, the thickness of the coating film becomes too thin to obtain a sufficient thickness at one time.

In the present invention, the use of a coupling agent is effective for stable dispersion of the metal oxide powder. Examples of the method of using the coupling agent include a method in which the coupling agent is directly added to a paste for forming a solid electrolyte and a method in which a metal oxide powder is treated with a coupling agent and used. As a method of treating the metal oxide powder, for example, a method of directly adding a coupling agent to the metal oxide powder and stirring and mixing (dry treatment method) or a method in which the coupling agent is previously dissolved in a solvent such as hexane and toluene, After mixing and stirring the manganese dioxide powder therein, a method of removing and drying the solvent (wet processing method) and the like are mentioned. As a coupling agent,
When dispersing the metal oxide powder in a dispersion medium containing a conductive polymer, the metal oxide powder is not particularly limited as long as it is easily compatible with the conductive polymer and can improve the dispersion stability. And silane-based, aluminum-based, titanate-based and zirconium-based coupling agents are exemplified as preferred. The addition amount of the coupling agent in the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, and preferably 0.5 to 2 parts by weight based on 100 parts by weight of the metal oxide powder. Particularly preferred. If the amount of the coupling agent is less than 0.1 part by weight, the dispersibility of manganese dioxide tends to decrease, and if it exceeds 10 parts by weight, the conductivity of the metal oxide powder surface tends to decrease.

The paste composition for forming a solid electrolyte of the present invention may be, for example, an antioxidant or a chelating agent, or any other additive having various functions, as long as it does not adversely affect the properties of the cured product of the paste and the coating film. Addition of a modifier or the like may be performed. In addition, carbon black, graphite carbon, or the like can be used in combination to impart conductivity. The amount of these used is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the metal oxide powder.

The paste composition for forming a solid electrolyte of the present invention is prepared by mixing a predetermined amount of (A) a metal oxide powder, (B) a conductive polymer, and (C) a solvent with a conventional stirrer, triturator, or the like.
It can be easily obtained by uniformly kneading or dispersing using a roll, a roll mill or the like, and a uniform and thick coating film can be obtained by a single application without changing the characteristics as a solid electrolyte. And can be suitably used as a solid electrolyte layer of a tantalum capacitor or the like.

The present invention also relates to a method for manufacturing an electronic component using the paste composition for forming a solid electrolyte. For example,
A solid electrolytic capacitor is formed by forming an anodized film on a sintered body obtained from a valve metal powder, immersing in a semiconductor mother liquor and thermally decomposing, then immersing in the solid electrolyte forming paste composition and drying the semiconductor. The layers are formed to produce a solid electrolytic capacitor.

More specifically, a preferable manufacturing method will be described. A valve metal such as tantalum is buried in one end of a tantalum lead wire or the like, the other end is pulled out, compression-molded with a press, and about 2000 ° C. in a vacuum. Heat at a temperature for several tens of minutes to form a sintered body. Next, the sintered body is welded to a metal bar such as stainless steel at a place such as a tantalum wire, and then the sintered body is formed by applying a voltage in a chemical solution such as nitric acid or phosphoric acid to form Ta ₂ O.
The anodic oxide film of ₅ is formed. After forming the anodized film,
The sintered body is immersed in a semiconductor mother liquor such as a manganese nitrate solution to be impregnated with the liquid, fired at a temperature of 200 ° C. to 350 ° C., thermally decomposed, and a semiconductor mainly containing a manganese dioxide layer or the like inside the sintered body. Form a layer. After the thermal decomposition, the anodized film damaged by sintering by re-chemical formation is repaired. Then, the above immersion, firing and re-chemical conversion steps are repeated two or three times as necessary. Next, the sintered body was immersed in the paste composition for forming a solid electrolyte of the present invention for several seconds, first dried at room temperature, and then dried at room temperature.
The semiconductor layer such as a manganese dioxide layer is formed by drying at a temperature of from 200C to 220C, preferably from 180C to 200C.
The immersion and drying steps may be repeated two or more times as necessary to obtain a semiconductor layer having a sufficient thickness. After forming the semiconductor layer, carbon, silver paste, etc. are sequentially applied to form a cathode layer, and the sintered body is connected to a lead frame, or
The terminal is connected to a tantalum lead wire or the like drawn from the sintered body and the cathode layer. Finally, a resin exterior is formed by a resin dipping method or a resin molding method.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the scope of the present invention is not limited thereto.

Example 1 Manganese dioxide powder (RB- made by Mitsui Kinzoku)
A) Manganese dioxide powder containing β-type crystal structure (average particle size: 2 μm) obtained by heat-treating A) at 350 ° C. for 3 hours 1
100 parts by weight of n-hexane 60 parts by weight and Plenact AL-M (Ajinomoto, aluminum-based coupling agent) 1
A part by weight was added, and the mixture was stirred and mixed by a roll mill. Thereafter, manganese dioxide powder having a surface-treated β-type crystal structure was obtained except for n-hexane. 100 parts by weight of the above-mentioned surface-treated manganese dioxide powder, 20 parts by weight of a polyaniline powder (reagent, manufactured by Nitto Denko Corporation) pre-doped with phenolsulfonic acid (reagent, manufactured by Wako Pure Chemical Industries) and 80 parts by weight of cresol were dried in a nitrogen atmosphere. After premixing in a lower mortar, the mixture was kneaded with three rolls to obtain a paste composition for forming a solid electrovolume resistivity. Table 1 shows the results obtained by measuring the volume resistivity, dispersibility, and coating film thickness of the paste composition for forming a solid electrolyte. Volume resistivity, about 50μm coating film is formed on a ceramic plate by screen printing,
After curing, it was measured by a four-terminal method using a digital multimeter. Dispersibility was measured using a grain gauge according to JIS-K54.
The measurement was carried out according to the method of No. 00. The coating thickness is 1 × 2c
The ceramic plate having a thickness of m was dipped in the paste for about 3 seconds and then pulled up. After drying, the thickness of the coating film was measured using a micrometer.

Example 2 20 parts by weight of the polyaniline used in Example 1, 2 parts by weight of Prenact AL-M and 80 parts by weight of cresol were added to 100 parts by weight of the surface-treated manganese dioxide powder used in Example 1 in a mortar under a dry nitrogen atmosphere. After premixing in the mixture, the mixture was kneaded with three rolls to obtain a paste composition for forming a solid electrolyte. Conductivity, dispersibility of this paste composition,
Table 1 shows the film thickness.

Example 3 The same experiment as in Example 1 was conducted except that the dispersion medium was toluene, and the volume resistivity, dispersibility, and coating film thickness of the obtained paste composition for forming a solid electrolyte are shown in Table 1. Indicated.

Example 4 The same experiment as in Example 1 was conducted except that the conductive polymer was polypyrrole, and the volume resistivity, dispersibility, and coating film thickness of the obtained solid electrolyte forming paste composition were shown in Table 1. It was shown to.

Embodiment 5 The coupling agent is Prenact KR TT
The same experiment as in Example 2 was conducted, except that S (manufactured by Ajinomoto Co., titanate-based coupling agent), and the volume resistivity, dispersibility, and coating film thickness of the obtained paste composition are shown in Table 1.

[0020]

Comparative Example 1 A manganese dioxide layer was formed on a ceramic substrate by a conventional method in which a 50% by weight manganese nitrate aqueous solution was thermally decomposed without using a paste composition in which manganese dioxide powder was dispersed, and the volume resistivity and coating film thickness were examined. The results are shown in Table 1. From the results in Table 1, it was found that the paste composition for forming a solid electrolyte of the present invention has good dispersibility and excellent conductivity, and can obtain a predetermined film thickness by one application.

[0021]

[Table 1]

[0022]

The paste composition for forming a solid electrolyte according to claim 1 is excellent in conductivity and can obtain a predetermined film thickness by one application, so that the solid composition of an electronic component such as a tantalum capacitor can be obtained. It is suitable for forming an electrolyte layer.
According to the second aspect of the present invention, the composition effect of the first aspect is exhibited, the uniformity of the coating film can be further improved, and an effect of excellent stability during use can be obtained. Claim 3
According to the described invention, in addition to the effect of the invention of claim 2,
By limiting the particle size of the metal oxide powder, the uniformity of the coating film can be improved, and a coating film with uniform film quality can be produced.
According to the fourth aspect of the invention, using the paste composition for forming a solid electrolyte according to the first, second, or third aspect, the production time can be reduced, and leakage current characteristics, heat resistance, moisture resistance, etc., and accuracy of external dimensions can be improved. An electronic component having a solid electrolyte layer having improved is provided.

Claims (4)

[Claims] 1. A paste composition for forming a solid electrolyte, comprising (A) a metal oxide powder, (B) a conductive polymer and (C) a solvent. 2. The composition according to claim 1, further comprising a silane-based, titanate-based, aluminum-based or zirconium-based coupling agent.
The paste composition for forming a solid electrolyte according to claim 1. 3. The metal oxide powder has an average particle size of 0.01-5.
The paste composition for forming a solid electrolyte according to claim 1 or 2, which has a thickness of 0 µm. 4. A method for producing an electronic component using the paste composition for forming a solid electrolyte according to claim 1, 2 or 3.