JPS62118510A - 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] The present invention relates to a method for manufacturing a solid electrolytic capacitor with good performance using a lightning conductive polymer compound as a solid conductor. It is something.

[Prior art] Conventional solid electrolytic capacitors, such as aluminum electrolytic capacitors, are: [Touching place]! l The structure consists of a porous aluminum foil with a large Lk specific surface area, an aluminum oxide layer as a dielectric material, and an electrolytic paper between the cathode foil and impregnated with a liquid electrolyte. Since it is liquid, it causes problems such as liquid leakage, which is preferable b.
Therefore, attempts have been made to replace this conductive layer with a solid 1j lightning body. These solid electrolytic capacitors have a structure in which a solid conductor is attached to a film-forming metal such as aluminum or tantalum that has an anodized film, and the solid conductor of this type of solid capacitor mainly contains manganese nitrate. Manganese dioxide, which is formed by the thermal decomposition of However, this solid electrolyte]
J 4J: The high heat required during thermal decomposition and the oxidizing effect of the NOx gas generated can damage the oxide film of metals such as aluminum and tantalum, which are dielectrics. There are disadvantages such as a decrease in leakage current, a deterioration of the lightning protection properties, and a process called re-formation. .

In order to compensate for these drawbacks, attempts have been made to use highly conductive organic semiconductor materials as a solid conductor as a method of forming a solid conductor layer without applying high heat. An example of this is JP-A-IF, ? As described in Japanese Patent No. 52-79255, a solid electrolytic capacitor in which a conductive organic compound containing a 7,7,8,8-tetracyanoquinodimethane <TCNQ) complex salt is the main component of the solid S conductor is known. There is.

However, in this solid electrolytic capacitor, the TCNQ salt has poor adhesion to the complex salt oxide film, and the conductivity is also 10-1.
3 to 10"2S/CIl+, which is insufficient, the capacitance value of the capacitor is small, the dielectric loss is large, and the thermal stability over time is also poor, and the reliability i (1 is low.
Since the NQ Iff salt is expensive, there is a problem in that the manufacturing process of the entire solid electrolytic capacitor is expensive.

In recent years, lightning conductivity is high and adhesion with dielectric coatings is J:
Attempts have also been made to provide solid electrolytic capacitors using inexpensive conductive polymer compounds as solid conductors. In this attempt, when depositing a conductive polymer compound onto a film of porous metal oxide used as a dielectric, the conductive polymer compound was skillfully introduced into the pores of the porous metal oxide. The most important issue is to stabilize the situation.

In general, conductive polymer compounds are insoluble and infusible, and have extremely poor formability and additive properties; therefore, most conductive polymer compounds cannot be processed by melt molding or casting methods. Since the formation of the metal oxide is not possible, it is difficult to introduce the circular conductor into the pores of the porous metal oxide, and therefore the solid electrolyte 1 [Problems that the invention solves] The purpose of the present invention is to solve the problems of the prior art described above, and to create a porous M electric body. It is possible to easily introduce a conductive polymer compound with excellent performance as a solid conductor into the pores of the pores, and it also has good adhesion with the dielectric coating, and is low in manufacturing cost. An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor using a polymer compound as a solid conductor.

[T stage for solving the problem] According to the present invention, in producing a solid electrolyte in which a conductive polymer compound is used as a circular conductor, the conductive polymer compound is subjected to an electrolytic polymerization method. Provided is a method for forming a solid electrolytic capacitor, which is characterized by depositing and growing a porous dielectric layer on the surface of the porous dielectric layer.

In the method of the present invention, the conductive polymer compound used as the solid conductor deposited and grown on the surface of the porous dielectric layer by electrolytic polymerization refers to a polymer compound having a π-electron conjugated system. It is desirable that the electrical conductivity is 1O-3S/cm or more. Typical examples of such conductive polymer compounds include polyacetylene, polyparaphenylene, polypyrrole, bothiophene, polycyanoacetylene, polyisothianaphthene, polycyanoethylene, polyaniline, polyphthalocyanine, and the seven polymers constituting these polymers. Examples include dielectric polymers and the like. Among these 'Ml-like polymer compounds, preferred conductive polymer compounds include polythiophene,
Examples include poly(1,3-isodeanaphthene) and polypyrrole, and more preferably polythiophene.

Some of the above sum 11 polymer compounds contain 10
Some have electrical conductivity of more than 'S/cm',
Electricity supply! There are some materials whose electrical conductivity is increased to 10 to 3 S/cm or more by doping them with j-type or electron-withdrawing dopants, and any of them can be used as a solid conductor.

In the latter case, either chemical doping or electrochemical doping may be used for doping. Chemical dopants include various conventionally known electron-accepting compounds and electron-73 compounds, such as (I) iodine, bromine, and bromine iodide.
(II) Metal halides such as arsenic pentafluoride, ambumonate pentafluoride, silicon tetrafluoride, phosphorus pentafluoride, phosphorous pentafluoride, aluminum chloride, aluminum bromide and aluminum fluoride, (I[[ ) Protonic acids such as sulfuric acid, nitric acid, fluorosulfuric acid, 1- to 1-difluoromethanesulfuric acid, (rV) oxidizing agents such as sulfur trioxide, nitrogen dioxide, difluorosulfonyl per-J, l-cyto, )A(I C,
OOl, (■I) T l~5 Schiff/Ethyl/n, Te1-lacyano4ninodimethane, Floranil, 2.
3-dichloro-5,6-dicyatsubarabenzoquinone, 2
．． 3-dibromo-5,6-cycyanoparabenzoquinone,
(■) Alkali metals such as Li, Na, and Ni can be used. - 10,000, Dopants to be electrochemically doped include (I) PFii, Sb Fi, As F
ii, a halide anion of an element of the Va group such as SbCρi, BF; a halide anion of an element of the Ila group such as i, a 1]gen anion such as I (Ii >, Br -, C, II-), such as CρOa Anionic dopants such as perchlorate anions and (T)L,i''.

Na, ni+, Rb", Cs"'/) Like87
metal ion, general formula R4-xM+1-]
x or RM + (in the formula, R is an alkyl group from C1 to C1o, )lyl, herophenyl, alkylphenyl, etc.0) 71J −/L, i, M are N, P, As,
MlG, L; O or 3. x represents O or 1. ] Examples include cations and dopants such as tetraalkylammonium ions, tetraalkylphosphonium ions, tetraalkylarsonium ions, [-realkyloxonium, trialkylsulfonium ions, etc., but are not necessarily limited to these. It's not something you can do.

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.

The electrolytic polymerization method according to the present invention () refers to, for example, the above-mentioned conductive polymer compound! This is a method in which an electrolytic solution containing a monomer for polymerization is electrolyzed to carry out oxidative polymerization of a C monomer.
This can be done by selecting a known appropriate polymerization strip 1'1 for each (Φjlq) combination L summer.
In the electrolytic polymerization method, which was first known in 11°C, the anode is
For example, electrochemically stable materials such as gold and platinum are used, but in the present invention, for example, aluminum
In the anode, a material in which the surface of a metal that is extremely difficult to oxidize is covered with a porous dielectric, such as an oxide such as aluminum, is used between the anodes. By protecting the metal surface of this porous dielectric, it is possible to carry out only 7-mer polymerization without proceeding with oxidation of the metal.

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

The polymerization time is appropriately selected by observing and judging the precipitation and growth rate of the conductive polymer compound, but is generally about several minutes to several hours.

Although there is no particular limitation on the polymerization pressure, generally, before the start of polymerization, the pores of the porous dielectric layer are filled with an electrolytic solution by a pressure reduction operation, and then the pressure is returned to normal pressure and the polymerization operation is performed.

[Effects of the Invention] The solid electrolytic capacitor manufactured by the method of the present invention has significantly superior capacitance, dielectric loss, and stability over time compared to conventional solid electrolytic capacitors using inorganic oxide semiconductors or organic semiconductors. It has performance.

Moreover, the solid type produced by the method of the present invention = 8
- Solvent capacitors have the following advantages over conventionally known solid electrolytic capacitors:

■ Apply electricity to the porous dielectric layer without heating it to high temperatures.
! '? Since a 4fI polymer compound is formed, there is no risk of damaging the oxide film of the anode, and there is no need to perform anodic oxidation (reformation) for repair. Therefore, the rated voltage can be increased several times compared to the conventional one, and the same capacity and rated voltage]
In order to obtain the undenna, the shape can be made smaller compared to the conventional -b.

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

(2) It is possible to produce a high-voltage resistor.

(2) Since the conductivity of the conductive polymer compound is as high as -1 min at 1O-3S/cm or more, there is no need to prepare a conductive layer such as graphite, and the process for this purpose can be simplified.

■　Good frequency characteristics 1゜ ■! II″#i] S1- is low.

[Examples] Hereinafter, the present invention will be explained in more detail by referring to Examples and Comparative Examples.

The characteristic values of the solid electrolytic capacitors on each side 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 produce a porous aluminum foil with an average pore diameter of 2 μTrL and a specific surface area of 12 m, 2/g. The etched aluminum foil was then immersed in an ammonium borate solution, and a thin dielectric layer was electrochemically formed on the aluminum foil in the solution.

The aluminum foil produced in this way was used as an anode, and the platinum plate was used as a cathode.
fJ thiophene 0.05 moil/, OliB
A current of 15 to 20 V and 11 mA/cm2 was applied to a benzoni-1-lyl solution containing F4 for 4 hours at room temperature and pressure in an argon gas atmosphere to electrochemically polymerize diophene and form a Bordge A phen film on the anode. It was precipitated. The conductivity of this polydione film was 108/cm. Use aluminum foil for the cathode and seal it with rubber to make it solid? A solution of ti = 1 was created.

Example 2 Using the same anode as in Example 1 and using a carbon plate as a cathode, 0.1 mofJ/fJ of 1,3-isodeanaphthene and 0.051110 fJ/! In an acetonitrile solution containing sulfonium chloride, etc., at room temperature and LE in an argon gas atmosphere, apply a voltage of 10 to 15 V% at normal LE.
A current of 1 mA/cm2 is passed for 4 hours, 1,
3~ Electrochemical polymerization of isodeanaphthene to deposit a poly(1,3-isodeanaphthene) film on the anode plate μk. The lightning conductivity of this poly(1,3-isodeanaphthene) film was 5 S/cm.

A solid electrolytic capacitor was fabricated by using aluminum foil as a cathode and stopping it with rubber.

Example 3 Using the same anode as in Example 1 and using a platinum plate as the cathode, pyrrole of 0.1 mo, Il /ρ and 0.05 mo of
j/, Q to an acetonitrile solution containing tri-n-butylammonium salt of p-toluenesulfonic acid at room temperature and pressure in an argon gas atmosphere at 15 to 20 mA/c.
A current of m2 was applied for 4 hours to electrochemically polymerize the pyrrole and deposit a polypyrrole film on the anode plate.

The electrical conductivity of this polypyrrole film was SO8/cm. A solid electrolytic capacitor was fabricated by using aluminum foil for the cathode and sealing it with rubber.

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

table

Claims (1)

[Claims] In manufacturing a solid electrolytic capacitor using a conductive polymer compound as a solid conductor, the solid electrolytic capacitor is characterized in that the conductive polymer compound is deposited and grown on the surface of a porous dielectric layer by an electrolytic polymerization method. Production method.