JPH0350811A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To enable easy manufacture of a solid electrolytic capacitor being excellent in an electrical characteristic by forming a solid-electrolyte layer on an anodic oxidation film on the surface of a valve-action metal by conducting electrolytic oxidation polymerization of a compound selected from a group of specific heterocyclic compounds. CONSTITUTION:A heterocyclic compound of a monomer which can be led to a polymer solid electrolyte giving excellent characteristics as a solid electrolytic capacitor and of which an anodic oxidation potential is low is selected as a material. The heterocyclic compound used as a material for polymerization is a compound expressed by a formula (I) or (II). As for a method of polymeriz ing the heterocyclic compound, a method using anodic oxidation in an ordinary electrolytic reaction is adopted. In this method, besides, a supporting electrolyte can be employed. It is preferable that the electrolytic oxidation polymerization of the heterocyclic compound is executed by using a solvent which can dissolve the compound together with the supporting electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a solid electrolytic capacitor in which a polymer solid electrolyte layer is formed on the surface of a valve metal such as aluminum or tantalum that has been oxidized.

(Prior art) Conventionally, in solid electrolytic capacitors whose anode body is made of fL material with valve action such as aluminum or tantalum, manganese dioxide (Mn02) or tetracyanoquinodimethane <TCNQ) iff salt has been used as the solid electrolyte. something is well known. These solid electrolytes are immersed in coating components,
This is done by repeating heating and solidification, but the process is complicated and it is difficult to control the thickness of the solid electrolyte. Since it is a complicated process and has low productivity, it is unsuitable for manufacturing small-capacity capacitors, and conversely, high-temperature heating is required for manufacturing large-capacity capacitors, which increases the effect of thermal distortion. Since these solid electrolytes are immersed and solidified by heating at a considerably high temperature, it is difficult to create a pattern on the surface of the anode body using insulating wooden members to form an electrolyte layer locally. The solid electrolyte is a granular material, and it is not possible to perform a process such as cutting into chips after forming a solid electrolyte or other chips. Therefore, at present, these technologies can only realize medium-capacity capacitors.

In recent years, attempts have been made to compensate for these drawbacks by providing solid electrolytic capacitors having a conductive vol layer such as a thiophene polymer as a solid electrolyte.

If this technology is used, most of the above problems are solved, and there is a large degree of freedom in process selection, making it possible to manufacture a wide range of products from chip-type small capacitance capacitors to large capacitance capacitors using appropriate processes.

(Problem to be Solved by the Invention) The polymer solid electrolyte layer is made of aluminum oxide, aluminum oxide (A12o, ), tantalum oxide ('1''a20s>, etc.) on the surface of a valve metal such as aluminum or tantalum, and thiophene, etc. The electrolytically oxidized heavy polymer can be formed well on the surface of metals such as gold and platinum, but it is not good to form on the surface of the anodic oxide film.One of the reasons is that For example, the electrolytic oxidation potential of thiophene is about 2.0 VVSSCE, which is quite high, so it is difficult to perform electrolysis on an anodic oxide film such as aluminum oxide or tantalum oxide.The purpose of the present invention is to solve the above drawbacks. An object of the present invention is to provide a method for easily manufacturing a solid electrolytic capacitor in which a polymer solid electrolyte layer that provides good characteristics as a capacitor is formed on a valve-acting metal anodic body whose surface has been anodized. .

(Means for Solving the Problems) The present invention has been made to solve the above problems, and is a method for manufacturing solid electrolytic capacitors in which a solid electrolyte layer is formed on an anodized film on the surface of a valve metal. By selecting a monomer heterocyclic monomer as a raw material that can lead to a polymer solid electrolyte that provides good characteristics as a solid electrolytic capacitor and has a low anodic oxidation rate, excellent electrical characteristics can be achieved. This made it possible to easily manufacture solid electrolytic capacitors.

The heterocyclic compounds used as heavy raw materials in the present invention are compounds represented by formulas (1) to (II).

(In the formula, n represents an integer of 3 to 10, H- and -〇-, and Y represents -8CH-.) Typical compounds include 4゜X is -S--N, NH and -CH 5゜6-dolihydro-2-thiopentalene, 4.5,6.7-tetrahydro-2-thioindene, 1.4-dithiopentalene, benzo[b]thiophene, cheno[3゜2-b]virol, 1-azabicyclo [3,3,0]octa-2,4 diene, 1-azabicyclo[3°4.0]nona-2,4-diene, 1-oxabicyclo[3,3,0]octane-2
, 4-diene, 1-oxabicyclo[3,4,0]nona-2,4-diene, and the like.

The above-mentioned heterocyclic compound can be polymerized using a conventional electrolytic reaction. An oxidation method is used, such as a current density of 0.01 to 100 A/eI 112, an electrolytic pressure of 1 to 300 cm, a constant current method, a constant voltage method, and any other method.

A supporting electrolyte may be used in this method. Supporting electrolytes include salts of borodisalicylic acid such as tetraalkylammonium 11 salts of borodisalicylate and dialkyl ammonium borodisalicylates, aromatic sulfonic acids or their salts such as benzenesulfonic acid and dodecylbenzenesulfonic acid, oxalic acid, and adipine. Examples include acids. These can also be used in combination.

The electrolysis of the heterocyclic compound is preferably carried out using a solvent that can dissolve the compound together with the supporting electrolyte.

Examples of these solvents include aliphatic nitriles, aliphatic ketones, aliphatic ethers, aliphatic or aromatic hydrocarbons, esters, alcohols, water, etc., but in particular acetonitrile, brobylene carbonate, etc. Nate etc. are preferred.

(Example) The present invention will be specifically explained below using Examples, but the present invention is not limited to the Examples.

Example 1 High-purity aluminum that has been etched in advance is etched! A 1 cm x 1 cm chemically formed foil with a dielectric layer of aluminum oxide formed on the surface was used as an anode, and an aluminum plate was used as a cathode. Tet-laethylammonium borozyza, notylic acid Using an acetonitrile solution with a concentration of 0.1 mol/1, electrolytic oxidation polymerization was carried out in an electrolytic bath at a current density of 2.5 + nA/c stone 2 for 1 hour to form a polymer solid on a chemical foil. An electrolyte layer was formed. After this chemically formed foil was taken out, washed, and dried, the cathode was taken out and sealed with resin using carbon paste and silver paste.

Examples 2 to 7 Capacitors having corresponding polymer solid electrolyte penetrating layers were produced in the same manner as in Example 1 except that the type of polycyclic compound monomer used in Example 1 was changed.

The monomers used in each example are shown in Table 1.

Further, the electrical characteristics of the electrolytic capacitors obtained in each example are shown in Table 2 together with the oxidation potential of the multi-ring compound and the electrolytic potential of the aluminum oxide electrode.

In view of the results of these examples in Table 1, the method of the present invention performs electrolytic oxidation polymerization of a 7-mer with a low oxidation potential, so polymerization easily progresses onto the anodic oxide film on the surface of the S-valve metal. It can be seen that the solid electrolytic capacitor formed by the method described above exhibits excellent electrical characteristics such as a low equivalent series resistance value at high frequencies and a high capacitance per unit area.

(Effects of the Invention) As explained in detail above, according to the method of the present invention, specific heterocyclic compounds represented by the above formulas (1) to (■) are used as heavy raw materials for electrolytic acids. So A I 20
The solid electrolytic capacitor can be easily stacked on a first grade anodic oxide film, and a solid electrolytic capacitor having excellent electrical characteristics can be obtained.

Claims (1)

[Claims] (1) In the manufacturing method of solid electrolytic capacitors in which a solid electrolyte layer is formed on the anodic oxide film on the valve metal surface, the following formulas (I) to (II) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, n is an integer from 3 to 10, X is -S-, -NH- and -O-, Y is -S-, -NH- and -CH=CH-
A method for manufacturing a solid electrolytic capacitor, comprising forming a solid electrolyte layer by electrolytically oxidizing a compound selected from heterocyclic compounds represented by