JPS62118511A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for manufacturing a solid electrolytic capacitor with good performance using a conductive polymer compound as a solid conductor.

[Prior Art] Conventional solid electrolytic capacitors, such as aluminum electrolytic capacitors, are made by providing an aluminum oxide layer as a dielectric on an etched porous aluminum foil with a large specific surface area, and using electrolytic paper between the cathode foil and the etched porous aluminum foil. It has a structure impregnated with a liquid electrolyte, but since the electrolyte is liquid, it causes problems such as leakage, which is not desirable.
Therefore, attempts have been made to replace this conductive layer with a solid layer. These solid electrolytic capacitors have a structure in which a solid conductor is attached to a film-forming metal such as aluminum or tantalum with an anodized film, and the solid conductor of this type of solid capacitor is mainly made of manganese nitrate. Manganese dioxide, which is formed by the thermal decomposition of However, in solid electrolytic capacitors, the high heat required during thermal decomposition and the oxidizing effect of the NOx gas generated damage the oxide film of the metal such as aluminum or tantalum, which is the dielectric material, and as a result, the withstand voltage decreases. However, there are extremely serious drawbacks such as increased leakage current and deterioration of dielectric properties.

In order to compensate for these drawbacks, attempts have been made to convert an organic semiconductor abrasive material with high conductivity f1 into a solid conductor, such as the Buno method, which forms a solid># lightning body layer without applying high heat. For example, 7,7,8,8-detracyanoquinodimethane (
TCNQ)! A solid electrolyte in which an organic compound containing a fi salt is used as a main component of a solid conductive body is known. However, this solid electrolyte]
CN Q♀j salt has poor adhesion to the anodic oxide film and has a conductivity of 10-3 to 10'S/
Since it is less than 1 minute per centimeter, the dielectric loss is small, the dielectric loss is small, and the thermal stability over time is poor and reliability is low. Further, since the TCNQ#ft salt has a high cost 1~, there is a problem in that the production of the entire solid-state electrode 1j is expensive.

Bamboo has a high conductivity, has a dielectric coating, and has a high conductivity.
<Also, solid electrolysis using an inexpensive conductive polymer compound as a solid conductor] 111! Attempts have been made to reduce the thickness of the porous metal oxide when depositing a conductive polymer compound on the porous metal oxide film used as a dielectric. Thunderbolt 1jI+ in the pore
Introducing ``II molecular compounds into I waters and making them habituated to humans is considered an important issue by [i5 and others].

In general, conductive t'l polymer compounds are insoluble and infusible, and their excipients 111, +-f1 are poor in color. For this reason, most conductive polymer compounds [well, melt molding, key switch]
Since it is not possible to form a solid conductor with <-1, etc., the solid conductor cannot be introduced into the pores of a porous metal oxide while maintaining 4T. Therefore, it cannot be used for solid electrolysis in many cases. We solved the problems of the technique in one go, and added solids (Al) into the pores of the porous body.
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Can a polymer compound be easily introduced, and can it also be used with a dielectric coating? A solid electrolyte that uses a solid electrolyte that uses a polymer compound that has a good f1 and a high fτ゛, and has a low susceptibility I.
The production of Ndenri 1 > the offering of 1;♂ (there is).

. [Solving the Problems I, Second Section 91 According to the present invention, in manufacturing a solid electrolytic converter in which an electric +r>-++ polymer compound is made into a solid electrolyte, the conductive high By carrying out an electrolysis procedure starting from the metal surface of the porous dielectric material where the metal is partially exposed, the molecular compound is precipitated and grown on the surface of the porous dielectric layer, and then anodized. A method of manufacturing a solid electrolytic condenser is provided, which comprises forming a dielectric layer on an exposed metal surface using Ni.

In the method of the present invention, an IWf polymer compound used as a solid conductor is deposited and grown on the surface of a porous dielectric layer by electrolysis starting from the metal surface of a porous dielectric layer where metal is partially exposed. is a polymer compound having a π-electron JL system, and has an electrical conductivity of 1O-3S/c
It is desirable to have a value of m or more. Typical examples of such Ti electrically conductive bulk polymer compounds include polyacerene, polyparaph-J-nylene, polypyrrole, bodeofene, polycyanoaledylene, polyisodeanaphthene, polyacerene, polyaniline, polyphthalocyanine, and the seven polymers constituting these polymers. Examples include dielectric polymers and the like. Among these molecular compounds with high J properties, examples of conductive polymer compounds with high J properties include bolib A) More preferably, polybuophene can be mentioned.

Some of the above conductive polymer compounds contain 1O
Some have an electrical conductivity of -3S/cm or more,
When doping an electrically conductive material (1 or an electron-withdrawing dopane), there is also a material that has an electrical conductivity of 1) or an electron-attracting dopane, which has an electrical conductivity of 1) or more than 1), and eventually becomes a solid conductor. In the latter case, any of doping methods such as GJ doping, chemical doping, and electrochemical doping may be employed.

Dopanes 1 to 1 to be chemically doped include various conventionally known electron-accepting compounds and electrons! j
compounds such as ([) iodine, bromine and bromine iodide, (■ [) arsenic pentafluoride, anti-t
metal octarides such as silicon tetrafluoride, phosphorus pentachloride, phosphorus pentafluoride, aluminum chloride, aluminum bromide and aluminum fluoride, (III) sulfuric acid, nitric acid, fluorosulfuric acid, trifluoromethane 1iliQ and chlorosulfuric acid. (IV) oxidizing agents such as sulfur trioxide, nitrogen dioxide, difluorosulfonyl per 4-cyto, (V) A
g (j104, (■) Tetracyanoedylene, Tetracyanoquinodimethane, Floranil, 2,3-dichloro-
5,6-disiacbenzoquinone, 2,3-dibromo-5,6-disiacbenzoquinone, (■) Li, N
Alkali metals such as a, ni, etc. can be used. On the other hand, dopants for electrochemical (J-doping) include (I) halide anions of Va group elements such as PFo, 5bFii, ASFi, and SbCβ1, halide anions of l[a group elements such as 11Fi, I- (I
:i>, anion dopants such as halogen anions such as 3r-, Cjl-, perchlorate anions such as C90i, and (TI)Li+.

Alkali metal ions such as Na, K", Rh", Cs4, general formula R4, M"Hx or 83M1+ (wherein R is a C1 to C1o argyl group, phenyl, ha[
1) ■ Aryl group such as nyl, alkylphenyl, MC1
, N, l), As, Ml is O or S, x is 0 or 1. ) represented by jtraalkylammonium ion A, te1-laalkylbosphonium ion, detraalyl arsonium ion, trialni1lua1 :I-
Examples include, but are not necessarily limited to, cations such as sonium, trifluorkylsulfonium ions, and dopant ions.

The type of porous dielectric used in the present invention is not particularly limited, but oxides of metals such as aluminum, tantalum, and niobium can be suitably used. There are no particular limitations on the method of partially exposing the metal surface on the porous dielectric, for example, using the metal surface generated when cutting the porous dielectric, or exposing the metal surface in spots on the - side. can be used.

The surface area of the exposed metal part of the porous dielectric is the conductivity - Ω
- = 7 - Although it cannot be determined unconditionally as it varies depending on the type of polymerization polymer that provides the polymeric compound, it is generally 0.001 to 10%, preferably 0. It is preferably within the range of .01 to 5%.

The electrolytic polymerization method used in the present invention refers to a method in which, for example, an electrolytic solution containing a seven-termer for polymerization that provides the electrically conductive polymer compound is electrolyzed to carry out oxidative polymerization of the seven-termer. This can be carried out by selecting appropriate known polymerization conditions for various types of polymers.In the electrolytic polymerization methods known so far, electrochemical polymers such as gold or platinum are used as an anode. Stable materials are used, but in the present invention, as mentioned above, a porous dielectric material with partially exposed metal is used.The polymerization reaction proceeds rapidly starting from this metal surface, and it becomes conductive. The polymer compound grows to cover the surface of the dielectric material.

The polymerization temperature for electrolytic polymerization is not particularly limited, but it is generally carried out at a humidity of -60°C to 80°C, preferably -20°C to 30°C.

The polymerization time is determined by observing the precipitation and growth of the conductive polymer compound, but is generally in the range of several minutes to several hours.

There is no particular limitation on the polymerization pressure, but generally, before the start of polymerization, the pressure is reduced to return the pores of the porous dielectric layer to normal pressure, which is filled with an electrolytic solution, and then the polymerization operation is carried out.

After polymerization, anodic oxidation (post-chemical formation) is used to repair and cover the metal surface of a porous dielectric where metal is partially exposed.
It is carried out using non-aqueous systems, aqueous systems, solid phase systems, etc.
111 Select an appropriate system depending on the type of polymer compound 1J
can be done.

[Effect of the invention 1] The solid electrolytic capacitor manufactured by the method of the present invention has improved capacitance, dielectric loss, and stability over time compared to solid electrolytic capacitors using conventional inorganic oxide semiconductors or solid-state semiconductors. It has extremely poor odor performance.

Furthermore, the solid electrolytic capacitor produced by the method of the present invention has the following advantages compared to the conventionally known solid FRSM 11 capacitor.

■ Since a conductive polymer compound can be formed on the porous dielectric layer without heating to high temperatures, there is no damage to the oxide film on the anode. Therefore, the rated voltage can be increased several times compared to the conventional capacitor, and the shape can be made smaller compared to the conventional capacitor, even though the capacitor has the same capacity and the same rated voltage.

■ Leakage current is small because the conductive polymer compound and dielectric coating have good adhesion.

■ Capacitors with high withstand voltage can be manufactured.

(2) Since the conductivity of the conductive polymer compound is sufficiently high at 10'S/cm or more, there is no need to provide a conductive layer such as graphite, and the culm for this purpose can be simplified.

■Good frequency characteristics.

■ Low manufacturing cost.

[Example] The present invention will be explained in more detail by referring to Examples and Comparative Examples.

Note that the characteristic values of each solid electrolytic capacitor are shown in the table.

Example 1 Aluminum foil with a thickness of 100 μm (purity 99.99%)
was used as an anode, and the surface of the foil was electrochemically etched by alternating direct current and alternating current to obtain a porous aluminum foil with an average pore diameter of 2 μm and a specific surface area of 127 rL2/g. The etched aluminum substrate was then immersed in an aluminum borate solution, and a thin dielectric layer was electrochemically formed in the solution on top of the aluminum substrate.

It was decided to cut the outer circumferential part of the aluminum tube () produced in this way, so as to partially expose the aluminum metal surface. The exposed portion of aluminum metal was 0.1% of the total surface area of the porous dielectric. This was used as an anode, and the platinum plate was used as a cathode.
/, Qthiophene and 0.05 mofl'/J I-i
[A benzonitrile solution containing 3F+ in an argon gas atmosphere at room temperature and normal pressure 'C: 4 to 5 V, 2 m A /
A current of cm 2 was applied for 2 hours to electrochemically polymerize thiophene to deposit a polythiophene film on the anode plate. The conductivity of this polythiophene film is 20
It was 8/cm. Next, using the aluminum foil covered with this polythiophene film as an anode and the platinum plate as a cathode, post-chemical conversion was performed in an ethylene glycol solution of ammonium borate at 9 V for 10 minutes. Thereafter, the chemical compound was used as an anode, aluminum foil was used as a cathode, and the capacitor was sealed with rubber to produce a solid electrolytic capacitor.

Example 2 Using the same anode as in Example 1 and a carbon plate as a cathode, 0.1 mo, O/ρ of 1.3=isothianaphthene and 0.05 ma1/1 of tetraphenylphosphium A were prepared. A current of 2 to 3 V and 11 mA/cm2 is applied to an acetonitrile solution containing chloride in an argon gas atmosphere at room temperature and pressure for 2 hours to electrochemically polymerize isothianaphthene and form polyisothianaphthene on the anode plate. A film was deposited. The electrical conductivity of this poly(1,3-isothianaphthene) film was 10 S/cm. After post-forming in the same manner as in Example 1, aluminum foil was used as the cathode and sealed with rubber to produce a solid electrolytic capacitor.

Example 3 Using the same anode as in Example 1 and using a platinum plate as a cathode, 0.1mofJ/, 11 pillars [1-pole 0.05m]
oj/41 p-toluenesulfonic acid tri-n-butylammonium salt in an acetonitrile solution containing 3 to 4 V11'rrLA at room temperature and pressure in an argon gas atmosphere.
A current of /cm2 was passed for 2 hours to electrochemically polymerize pyrrole and deposit a polypyrrole film on the anode plate. The electrical conductivity of this polypyrrole film was 50S/α. After post-forming in the same manner as in Example 1, aluminum foil was used as the cathode and sealed with rubber to produce a solid electrolytic capacitor.

Comparative Example A solid electrolytic capacitor was manufactured using the same aluminum foil as in Example 1 for the dielectric layer, using conventional manganese dioxide as the solid conductor, and having the cathode made of aluminum foil.

Claims (1)

[Claims] In manufacturing a solid electrolytic capacitor using a conductive polymer compound as a solid conductor, electrolytic polymerization of the conductive polymer compound is carried out starting from the metal surface of a porous dielectric material with partially exposed metal. A method for producing a solid electrolytic capacitor, which comprises depositing and growing a porous dielectric layer on the surface thereof, and then forming a dielectric layer on the exposed metal surface by anodic oxidation.