JPH0536574A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To prevent the title capacitor from being deteriorated by a leakage current after an electrolytic polymerization operation by a method wherein, in the electrolytic polymerization operation to form a polypyrrole chemically formed film on a chemically formed body, parts other than a part used to electrolytically polymerize the chemically formed body are masked electrically and an electric current flowing to the chemically formed body from a member for electricity-feeding use is stopped. CONSTITUTION:A solid electrolytic capacitor which uses a polypyrrole film formed in the following manner as a solid electrolyte is manufactured: pyrrole is electrolytically polymerized onto a flat board-shaped chemically formed body 1 provided with an oxide film on its surface. At this time, the chemically formed body 1 is separated from a cathode 3 connected to a power supply 2; they are immersed in an electrolyte 4 for electrolytic polymerization use; members 5, for electricity-feeding use, which are connected to an anode at the power supply 2 are arranged so as to be close to the oxide film on the chemically formed body 1; a voltage is applied; an electrolytic polymerization operation is executed. Thereby, the polypyrrole chemically formed film is formed on the chemically formed body 1. During the electrolytic polymerization operation, parts other than a part used to electrolytically polymerize the chemically formed body 1 are masked 6 electrically. Thereby, an electric current flowing to the chemically formed body 1 from the members 5 for electricity-feeding use is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor, and more particularly, to a method for manufacturing a solid electrolytic capacitor which prevents deterioration of LC (leakage current) after polymerization in electrolytic polymerization using an external electrode. Regarding the method.

[0002]

2. Description of the Related Art Electrolytic capacitors are compact, have a large capacity, are inexpensive, and exhibit excellent characteristics such as smoothing of rectified output.
It is one of the important components of electronic equipment. Generally, electrolytic capacitors are classified into an electrolytic solution type and a solid type. While the former interposes an electrolytic solution between an anode and a cathode, the latter has
A conductive oxide or organic substance such as manganese dioxide, lead dioxide, tetracyanoquinodimethane complex salt or polypyrrole is interposed as a solid electrolyte. Since the electrolytic capacitor of the electrolytic solution type is based on ionic conduction using a liquid electrolyte, the resistance is significantly increased and the impedance is increased in a high frequency region. Therefore, in terms of high frequency characteristics, the solid electrolytic capacitor is significantly superior.

As the solid electrolyte used for the solid electrolytic capacitor, the capacitance (Cap), dielectric loss tangent (tan δ), and leakage of the electrolytic capacitor which are defined by the conductivity and stability of the solid electrolyte itself and the properties of the solid electrolyte used. From the indicators of current (LC), equivalent series resistance (ESR), etc., polypyrrole is considered to be the best.

A solid electrolytic capacitor using polypyrrole as a solid electrolyte is disclosed in, for example, JP-A-63-17331.
No. 3 is described. Generally, when manufacturing this type of solid electrolytic capacitor, a thin film of polypyrrole is formed on the anode foil by chemical polymerization and electrolytic polymerization, and then terminals are bonded to this surface using a conductive paste such as silver paste. Take out the counter lead and coat it with epoxy resin to make a capacitor product.

On the other hand, with the recent progress in miniaturization of electric and electronic equipment, miniaturization of electrolytic capacitors is progressing,
There is an increasing demand for so-called chip capacitors.
When manufacturing this type of electrolytic capacitor, a manufacturing method of simultaneously manufacturing a large number of small-sized chipping materials having a certain quality is adopted. For example, when a polypyrrole polymer film is formed on a flat aluminum compound body by electrolytic polymerization using an external electrode, a voltage is simultaneously applied to a plurality of polymerized parts by using a plurality of current-carrying members such as a current-carrying pin or a current-carrying jig. It is common to apply the voltage to carry out electrolytic polymerization.

In such a case, when carrying out electrolytic polymerization, the chemical conversion body and the cathode connected to the power source are separated from each other and immersed in the electrolytic polymerization electrolytic solution, and the energizing member connected to the anode of the power supply is formed into the chemical conversion body. It is placed close to the oxide film of the polypyrrole (PP
y) A chemical conversion film is formed, but as shown in FIG. 3, a constant potential difference is generated between the current-carrying pin connected to the anode and the chemical conversion product (aluminum plate), so a reverse current flows through the conversion film, resulting in production. There is a problem that LC (leakage current) deterioration in the electrolytic capacitor element is remarkable.

[0007]

DISCLOSURE OF THE INVENTION The present invention focuses on the reverse current flowing from the current-carrying member to the chemical product in the electrolytic polymerization step carried out by using the external electrode when manufacturing the solid electrolytic capacitor. By blocking and removing the potential difference between the current-carrying member and the chemical compound, LC after polymerization
An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor that prevents deterioration.

[0008]

According to the present invention, there is provided a solid electrolytic capacitor having a polypyrrole film as a solid electrolyte formed by electrolytically polymerizing pyrrole on a flat-plate type conversion body having an oxide film on its surface. During production, the chemical compound and the cathode connected to the power source are separated from each other and immersed in the electrolytic polymerization electrolyte solution, and the current-carrying member connected to the anode of the power source is placed close to the oxide film of the chemical compound, and the voltage is applied. It consists of forming a polypyrrole chemical conversion film on the chemical conversion material by applying an electric current and flowing from the current-carrying member to the chemical conversion material by electrically masking a part other than the portion of the chemical conversion material to be subjected to the electropolymerization during the electrolytic polymerization. There is provided a method for manufacturing a solid electrolytic capacitor, which is characterized by blocking an electric current and preventing LC deterioration.

[0009] The flat plate type compound having an oxide film on the surface is
Usually, an aluminum chemical conversion plate whose surface is changed to an oxide film dielectric by electrolytic oxidation and has an etching chemical conversion layer is preferable. It is also possible to carry out electrolytic polymerization by forming a grid of an appropriate size on the chemical conversion plate.

In electropolymerization, a metal plate is used as the cathode, which is preferably stainless steel, nickel,
It can be composed of materials such as aluminum or platinum.

The current-carrying member is preferably a current-carrying pin,
In the present invention, this is used by connecting it to the anode of the power supply. It is possible to use a plurality of current-carrying members and simultaneously carry out electrolytic polymerization in a large number of compartments.

The electrolytic polymerization is carried out in an electrolytic solution for electrolytic polymerization.

It is preferable to dissolve pyrrole in the solvent for electrolytic polymerization at a concentration of 0.01 to 1 M / l.

The supporting electrolyte for electrolytic polymerization is 0.01-2 M /
1 BST / AN solution (provided that BST: borodisalicylic acid triethylamine salt or triethylammonium borodisalicylate, AN: acetonitrile) is suitable. In addition, propylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane and the like can be used as a solvent for electrolytic polymerization. In the present invention, NaNS (sodium naphthalene sulfonate) can be used at a concentration of 0.01 to 1 M / l.

The electrolytic polymerization is preferably carried out at a constant current of 0.1 to 10 mA for 1 to 3 hours. A current of 0.05 to 5 mA is applied to one energizing member.

In the electrolytic polymerization, the current flowing from the current-carrying member to the chemical compound is blocked by electrically masking the portion other than the portion of the chemical compound that is used for the electrolytic polymerization, and LC deterioration is prevented. All but the squares are masked by printing, coating, etc., and the mask is removed after electrolysis.

After the polypyrrole polymer film is formed on the flat plate type chemical compound by the above-mentioned method, it is made into an element by a conventional method and sealed to obtain a product.

[0018]

As described above, in the conventional electrolytic polymerization, a constant potential difference is generated between the current-carrying pin connected to the anode and the chemical conversion body (aluminum plate), so that a reverse current flows through the chemical conversion film. There is a problem that LC (leakage current) deterioration in the manufactured electrolytic capacitor element becomes remarkable.

The present invention has been completed as a result of diligent study, paying attention to a reverse current flowing from a current-carrying member to a chemical product in the production of a solid electrolytic capacitor, particularly in an electrolytic polymerization step using an external electrode. By preventing this reverse current and removing the potential difference between the current-carrying member and the chemical, LC deterioration after polymerization is prevented.

That is, according to the present invention, by electrically masking a portion other than the portion of the chemical conversion product to be subjected to the electrolytic polymerization during the electropolymerization, the current flowing from the current-carrying member to the conversion product is blocked, and the reverse conversion to the chemical conversion film An electric current can be blocked, and thus LC deterioration after polymerization can be effectively prevented.

[0021]

According to the present invention, when manufacturing a solid electrolytic capacitor, attention is paid to a reverse current flowing from a current-carrying member to a chemical body, particularly in an electrolytic polymerization step performed using an external electrode, and the reverse current is blocked. By removing the potential difference between the current-carrying member and the chemical compound, a method for producing a solid electrolytic capacitor is provided which prevents LC deterioration after polymerization.

[0022]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1 As shown in FIG. 1, a chemical conversion plate was used as a chemical conversion product, and an energization pin was used as an energization member to carry out electrolytic polymerization to prepare an element, and a solid electrolytic capacitor was manufactured by a conventional method.

That is, in this example, a solid electrolytic capacitor using a polypyrrole film formed by electrolytically polymerizing pyrrole on a flat type conversion sheet 1 having an oxide film on its surface as a solid electrolyte is manufactured. The chemical conversion plate 1 and the cathode 3 connected to the power source 2 are soaked away from each other that they are immersed in the electrolytic polymerization electrolytic solution 4, and the energization pin 5 connected to the anode of the power source 2 is arranged close to the oxide film of the chemical conversion plate 1. Then, a voltage is applied to form a polypyrrole conversion film on the conversion product by electrolytic polymerization. When the chemical conversion plate is electrically masked 6 by screen printing or coating during electrolytic polymerization, a current flowing from the energizing pin 5 to the chemical conversion plate 1 is blocked and a reverse current to the chemical conversion film is blocked.

22V having a grid of 3 mm × 3 mm
f, after subjecting the 10WV conversion plate to ordinary chemical polymerization,
Using an electrolytic solution containing 0.04 M / l NaNS (sodium naphthalene sulfonate) and 0.2 M / l pyrrole,
A 90 mA current was applied for 120 minutes (450 mass, 0.2 mA per pin) to carry out electrolytic polymerization, and the element obtained by masking the chemical conversion plate was examined for LC deterioration after polymerization. As a result, an element of 0.06 to 0.36 μA was obtained.

Comparative Example 1 As shown in FIG. 2, electrolytic polymerization was carried out in the same manner as in Example 1 except that masking was not carried out to manufacture a solid electrolytic capacitor. The LC of the obtained device after polymerization was 0.81 to
It became 4.80 μA.

As described above, comparing Example 1 with Comparative Example 1, it is understood that the deterioration of the device produced by masking is small and the reverse current to the chemical conversion film is prevented.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example in which a chemical conversion plate is used as a chemical conversion product, a conduction pin is used as a conduction member, and masking is performed to carry out electrolytic polymerization.

FIG. 2 is an explanatory view showing a comparative example in which a chemical conversion plate is used as a chemical conversion product, a conduction pin is used as a conduction member, and electrolytic polymerization is performed without masking.

[Figure 3] Conducting member (energizing pin) to chemical body (aluminum)
Explanatory diagram showing a mechanism of potential difference generation due to a reverse current flowing in the.

[Explanation of symbols] 1 chemical conversion plate 2 power supply 3 cathode 4 electrolyte solution 5 energizing pin 6 masking

Claims (1)

What is claimed is: 1. When producing a solid electrolytic capacitor using a polypyrrole film as a solid electrolyte, which is formed by electrolytically polymerizing pyrrole on a flat-plate type conversion body having an oxide film on its surface, The chemical body and the cathode connected to the power source are separated from each other and immersed in the electrolytic polymerization electrolyte solution, and the current-carrying member connected to the anode of the power source is placed close to the oxide film of the chemical body, and voltage is applied. It consists of forming a polypyrrole conversion film on the chemical conversion product by electrolytic polymerization, and blocks the current flowing from the current-carrying member to the conversion product by electrically masking the parts of the conversion conversion product other than those used for electrolytic polymerization during electropolymerization. And a method for manufacturing a solid electrolytic capacitor, which prevents LC deterioration.