JPH0574662A - Capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To realize a small-sized large capacity capacitor having excellent reliability of small deterioration of capacity, loss and high frequency impedance characteristics at high temperature and high moisture and a method for manufacturing the same in the capacitor having excellent frequency characteristics and reliability characteristics and the method for manufacturing the same. CONSTITUTION:A conductive polymer layer 3 is provided in at least one electrode of a capacitor, and a plurality of metal layers 4a, 4b are so formed that the entire layer 3 is covered with at least one of the layers 4a, 4b to constitute a capacitor. Since gas barrier characteristics of oxygen, water, etc., are improved by the plurality of metal layers provided on an outer layer and deterioration of oxidation of the layer 3 of an inner layer is suppressed, a capacitor having excellent reliability of small deterioration of capacity, loss and high frequency impedance characteristics even at high temperature and high moisture can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor having excellent characteristics such as frequency characteristics and reliability characteristics under high temperature and high humidity, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the digitization of electrical equipment,
The capacitors are also required to be small in size, large in capacity, and low in impedance in the high frequency range. Conventionally, capacitors used in the high frequency region include plastic capacitors, mica capacitors, and laminated ceramic capacitors, but it is difficult to increase the capacity of these capacitors due to their large size. On the other hand, as a large-capacity capacitor, there is an electrolytic capacitor such as an aluminum dry electrolytic capacitor or an aluminum or tantalum solid electrolytic capacitor. In these capacitors, the oxide film that serves as a dielectric is extremely thin, so a large capacity can be realized.However, since the oxide film is easily damaged, it is necessary to provide an electrolyte between it and the cathode to repair it. is there.

In the aluminum dry type capacitor, an etched positive and negative aluminum foil is wound around a separator and a liquid electrolyte is impregnated into the separator for use. Since this liquid electrolyte is ionic conductive and has a large specific resistance, the loss is large and the impedance frequency characteristic and temperature characteristic are significantly inferior.In addition, liquid leakage, evaporation, etc. are unavoidable, and the capacity decreases and the loss with the passage of time. I had a problem with an increase.

Further, since the manganese dioxide is used as the electrolyte in the tantalum solid electrolytic capacitor, the problems of temperature characteristics and changes with time such as capacity and loss are solved, but since the specific resistance of manganese dioxide is relatively high, the loss and impedance are relatively high. Was inferior in frequency characteristics to the monolithic ceramic capacitor or film capacitor.

In recent years, a heterocyclic monomer such as pyrrole or thiophene is electrolytically oxidatively polymerized by using a supporting electrolyte, whereby a conductive polymer containing an anion of the supporting electrolyte as a dopant is used as an electrolyte (true cathode). A solid electrolytic capacitor having excellent characteristics and temperature characteristics has been proposed (JP-A-60-37114, JP-A-60-244017).
(See the official gazette).

Furthermore, there has been proposed a large-capacity film capacitor in which a dielectric made of an electrodeposited polyimide thin film is formed on an etched aluminum foil, and then an electrolytically polymerized conductive polymer layer is formed to serve as an electrode (electrochemistry). Pp. 251-252 (1991)).

An example of the structure of a conventional electrolytic polymerization conductive capacitor is shown in FIG. Forming a dielectric layer 2 on the electrode 1,
Further, the conductive polymer electrode layer 3 is formed thereon by electrolytic polymerization. In an actual capacitor, a silver paint layer for drawing out an electrode may be provided with a graphite layer interposed to improve wettability. After further providing the electrode lead 5,
The surface is covered with the insulating resin film 6.

[0008]

However, in such a capacitor using the conventional electrolytically polymerized conductive polymer as an electrode, characteristics such as a decrease in capacitance, an increase in loss or an increase in impedance in a high frequency range are obtained under high temperature and high humidity. It was hard to avoid the deterioration.

This is because the conductive electrolytically polymerized polymer such as polypyrrole or polythiophene forming the conductive polymer electrode layer 3 uses BF ₄ ⁻ , ClO ₄ ⁻ , PF ₅ ⁻ , AsF ₅ ⁻ as a dopant. Therefore, these dopants are likely to cause dedoping under high temperature and high humidity, or even if using a dopant having a large molecular weight to prevent dedoping, a part of the polymer skeleton is oxidized and the length of the conjugated double bond is reduced. The reason is that the electric conductivity is lowered.

Since the latter oxidation proceeds even in the presence of an extremely small amount of oxygen and water, in the case of ordinary resin sheathing represented by dipping, powder coating, potting, injection molding or transfer molding, their diffusion and permeation are prevented. It is difficult to completely prevent it, and thus it is difficult to eliminate the deterioration of the characteristics, and a capacitor with high heat resistance could not be realized. In addition, when the anodized alumina layer is made of a dielectric material, its water resistance is low, and therefore deterioration of the anodized alumina layer itself cannot be avoided under high temperature and high humidity.

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a capacitor suitable for small size and large capacity, which has less deterioration of characteristics under high temperature and high humidity and has excellent reliability characteristics, and a manufacturing method thereof. It was made.

[0012]

The technical means of the present invention for attaining this object comprises a conductive polymer layer on at least one electrode of a capacitor having an electrode through a dielectric layer, A capacitor having at least one metal layer covering at least a part of a conductive polymer layer and at least another metal layer covering at least a part of the conductive polymer layer, and a method for manufacturing the same.

[0013]

According to the present invention, at least one electrode of the capacitor is composed of a conductive polymer layer and a plurality of metal layers to prevent permeation and diffusion of gas such as oxygen and water in the metal layer,
Capacitors with high reliability characteristics with little deterioration of the capacitor characteristics even under high temperature and high humidity because the deterioration of the electrical conductivity and the deterioration of the dielectric film due to the oxidation of the conductive polymer in the inner layer are prevented. Is obtained.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of a capacitor according to an embodiment of the present invention. In FIG. 1, a dielectric layer 2 is provided on a part of an electrode 1, and a conductive polymer layer 3 is formed so as to cover at least a part of the dielectric layer 2. A metal layer 4a is provided so as to cover the conductive polymer layer 3, and another metal layer 4b is formed with an insulating resin layer 6 interposed therebetween.
From the conductive polymer layer 3 and a part of the electrode 1 to the electrode lead 5a,
5b is taken out.

In this embodiment, in a capacitor including a conductive polymer layer 3 on at least one electrode separated by a dielectric layer 2, a metal layer 4 covering the conductive polymer layer 3 as a whole.
By disposing at least another metal layer 4b which covers a part or all of the above-mentioned conductive polymer layer 3 via the insulating resin film 6 and a, the gas barrier property is enhanced and the high temperature of the conductive polymer is increased. This is to prevent oxidation under humid conditions and further prevent hydration deterioration of the dielectric film, thereby realizing a highly reliable capacitor.

The reason why a plurality of metal layers are provided is as follows. That is, as shown in FIG. 1, an electrode (electrode lead 5) formed of the conductive polymer layer 3 on the same surface.
In the case of a) and the structure in which the other electrode lead 5b is provided in the portion where the dielectric layer 2 is not formed, even if only the conductive polymer layer 3 is covered with the metal layer 4a, the outside air is exposed through the end face portion. This is because penetration is inevitable. In such a case, the above-mentioned metal layer 4a is formed so as to cover the end face portion as well.
By further providing the metal layer 4b so as to overlap with, it is possible to prevent outside air from permeating into the conductive polymer layer 3. It suffices that the overlapping part of the metal layer 4b provided so as to be overlapped covers a part of the conductive polymer layer 3, but it prevents the permeation of outside air through minute defects that may occur in the metal layer 4a. Therefore, it is more desirable to provide it so as to cover the entire surface.

The metal layer 4a provided as the inner layer is preferably provided so as to form a part of the electrode, but it may be provided so as to be electrically insulated from the electrode if necessary. The outer metal layer 4b has two electrode leads 5 to prevent short circuit.
It is desirable to be electrically insulated from a and 5b.

The metal layers 4a and 4b need only have the required gas barrier properties. For example, at least one layer should cover the conductive polymer layer 3 over the entire surface.
It is also possible to provide more than one layer.

The metal layers 4a and 4b may be formed by any method as long as a dense thin film having a high gas barrier property can be formed. In particular, since the forming speed is fast and easy, electrolytic or electroless plating can be used. It is favorable.

The present invention only needs to have a conductive polymer layer and a metal layer, and as a base layer for the other metal layers, a graphite layer or a plating base layer for the purpose of improving adhesion, wettability or accelerating plating film formation. Etc. may be interposed between the conductive polymer layer and the metal layer. Any metal layer can be used as long as it has an electric conductivity that substantially functions as an electrode of a capacitor or for drawing out an electrode. Examples of such a metal include copper, nickel, chromium, cobalt, silver, Examples include gold, zinc, tin, rhodium, ruthenium and the like. Further, these alloys or compounds composed of these metals and other non-metals can be similarly used as long as they have the desired electric conductivity.

As the conductive polymer, a heterocyclic compound is used as a repeating unit, and any compound having a desired electric conductivity as a capacitor electrode can be used, but pyrrole or its derivative is used as a repeating unit. Conducting polymers are preferably used because of their ease of formation.

Any dopant can be used as long as it does not cause dedoping up to about 150 ° C. As an example of such a dopant, naphthalene sulfonate, alkyl natalene sulfonate, anthraquinone sulfonate, Sulfonated porphyrin,
Examples thereof include sulfonated phthalocyanine, polyvinyl sulfonate, polystyrene sulfonate and the like.

Any method may be used for the polymerization of the conductive polymer, but it is preferable because it is easy to form a thin film and a high coverage can be applied even to a surface expanded by etching, for example. The method by electrolytic polymerization is used.
In order to easily grow the electrolytically polymerized polymer on the dielectric, the surface of the dielectric may be partially or entirely made conductive by an appropriate method.

The dielectric layer may be composed of an anodized film of aluminum or tantalum, or may be composed of a polymer thin film such as electrodeposited polyimide, or composed of a polymer thin film whose surface is expanded by means such as etching. You can also do it.

The other electrode facing each other may have any structure, but when the dielectric layer 2 is composed of an anodic oxide film of a valve metal such as aluminum or tantalum, it is composed of the valve metal itself and etching. When the polymer thin film surface-enlarged by the above is used as the dielectric layer, the conductive polymer layer 3 is formed on both electrodes as shown in FIG. It is also possible to form a capacitor by forming a plurality of metal layers 4a and 4b.

Further details will be described below. (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described.

A 4 × 10 mm aluminum etched foil is divided into 3 mm and 6 mm portions so that the width is 1 across both sides.
mm polyimide tape is attached, an anode lead is attached to the former side, and the latter 4 × 6 mm portion is applied with 50% V at about 70 ° C. using a 3% ammonium adipate aqueous solution to form a dielectric film by anodic oxidation. Manganese nitrate 30
% Aqueous solution and further heated at 250 ° C. for 10 minutes to deposit pyrolytic manganese oxide on the surface to prepare an anode.

A stainless electrolytic electrode for electrolytic polymerization was brought into contact with this anode foil, and pyrrole monomer (0.25M), sodium triisopropylnaphthalene sulfonate (0.
1M) It was immersed in an electrolytic solution composed of water, and a voltage of 3 V was applied between the electrolytic polymerization second electrode provided separately from the electrolytic polymerization electrode to form an electrolytic polymerization film composed of polypyrrole.

The electropolymerized electrode was removed, washed with water and dried, and the electropolymerized membrane part was treated with stannous chloride dihydrate (30 g /
l) and concentrated hydrochloric acid (15 ml / l) in an aqueous solution for 2 minutes at room temperature, and an activator composed of an aqueous solution containing palladium chloride (0.5 g / l) and concentrated hydrochloric acid (0.5 ml / l) in normal temperature. After being dipped for 3 minutes respectively, it was dipped in a nickel electroless plating solution (Top Chemialoy B-1 manufactured by Okuno Seiyaku) at 60 ° C. for 30 minutes to form a nickel layer.

After this was washed with water and dried, the cathode lead was taken out with epoxy silver paint and aged at 16.2V. After that, an epoxy resin was applied over the entire surface of the electrode foil to form an insulating film, and the treatment after the above-mentioned sensitizer immersion was repeated once more to form a nickel layer on the entire surface to complete 10 capacitors. ..

The initial capacity and loss at 120 Hz, and the loss at 10 ° C under the conditions of 125 ° C and 85 ° C / 85%.
Average value of capacity and loss after holding for 00 hours (Table-1)
It was shown to. For comparison, Comparative Example 1 was prepared under the same conditions except that an epoxy silver paint layer was provided in place of the first nickel plating and the second nickel layer was not provided.
Zero capacitors were completed and the same characteristic evaluation as described above was performed, and the results are shown in (Table 1).

As is clear from (Table 1), the capacitor according to the present embodiment has an excellent effect in that the deterioration of capacity and loss can be reduced under the conditions of 125 ° C. and 85 ° C./85%.

As described above, according to this embodiment, by providing a plurality of nickel plating layers on the conductive polymer polypyrrole electrode formed on the anodized alumina dielectric layer, the capacity under high temperature and high humidity is increased. And small loss deterioration,
It is possible to obtain a highly reliable capacitor.

(Example 2) A second nickel layer was formed on the conductive polymer layer with a width of 6 mm including the anode attachment side.
A capacitor was completed in the same manner as in Example 1 except that the capacitor was provided so as to have a width of mm and overlap with the first nickel layer. The same characteristic evaluation as in Example 1 was performed for them. The results are shown in (Table 1).

As is clear from (Table 1), the capacitor according to the present embodiment has an excellent effect in that the deterioration of the capacity and loss can be reduced under the conditions of 125 ° C. and 85 ° C./85%.

As described above, according to the present embodiment, by providing the nickel-plated layer of a plurality of portions on the polypyrrole electrode of the conductive polymer formed on the anodized alumina dielectric layer, high temperature and high humidity can be obtained. It is possible to obtain a highly reliable capacitor with less deterioration in capacitance and loss under the capacitor.

As is clear from (Table 1), the solid electrolytic capacitor according to the present embodiment has an excellent effect in that the deterioration of capacity and loss can be reduced under the condition of 125 ° C.

(Example 3) Example 1 except that an electroless copper plating layer was formed using OPC copper T (electroless copper plating solution trade name: Okuno Seiyaku Co., Ltd.) instead of the top chemi-alloy B-1.
In the same manner as described above, 10 capacitors were completed. The same characteristic evaluation as in Example 1 was performed for them. The results are shown in (Table 1).

As is clear from (Table 1), the capacitor according to the present embodiment has an excellent effect in that the deterioration of capacity and loss can be reduced under the conditions of 125 ° C. and 85 ° C./85%.

As described above, according to this embodiment, by providing a plurality of nickel plating layers on the conductive polymer polypyrrole electrode formed on the anodized alumina dielectric layer, a plurality of nickel plating layers are formed under high temperature and high humidity. It is possible to obtain a highly reliable capacitor with little deterioration in capacity and loss.

As is clear from (Table 1), the solid electrolytic capacitor according to the present embodiment has an excellent effect in that the deterioration of capacity and loss can be reduced under the condition of 125 ° C.

(Example 4) Example 1 except that an electroless gold plating layer was formed by using OPC muden gold (electroless gold plating liquid trade name: Okuno Seiyaku) instead of the top chemi-alloy B-1. In the same manner, 10 capacitors were completed.
The same characteristic evaluation as in Example 1 was performed for them. The results are shown in (Table 1).

As is clear from this (Table 1), the capacitor according to this embodiment has an excellent effect in that the deterioration of the capacity and loss can be reduced under the conditions of 125 ° C. and 85 ° C./85%.

As described above, according to this embodiment, by providing a plurality of nickel plating layers on the conductive polymer polypyrrole electrode formed on the anodized alumina dielectric layer, a plurality of nickel plating layers can be formed under high temperature and high humidity. It is possible to obtain a highly reliable capacitor with little deterioration in capacity and loss.

In the examples, only the case where the metal layer is formed by electroless plating has been described, but it is clear that the same effect can be obtained by using electrolytic plating.

In the examples, only the case where the silver paint layer is not provided on the conductive polymer layer has been described. However, a silver paint layer may be provided, and silver in the silver paint layer may be used as a catalyst for electroless plating. You can also When a silver paint layer is provided, a colloidal graphite layer can be provided as an underlying layer.

Although only the case where an etched aluminum foil is used as the other electrode and an anodized alumina film is used as the dielectric in the embodiment, the tantalum sintered body and the anodized tantalum pentaoxide are used as the electrode and the dielectric, respectively. Can also be used as Furthermore, without using the anodic oxide film of the valve metal, for example using a polymer thin film as a dielectric,
The present invention can also be applied to a capacitor in which the other electrode is also made of a conductive polymer.

In the examples, only the case where pyrrole was used as the repeating unit constituting the conductive polymer was described, but if a polymer having a desired electric conductivity is obtained, another pyrrole derivative and thiophene or thiophene can be obtained. The derivative may be used as a repeating unit, and the present invention is not limited to that type.

In the examples, only the case where the alkylnaphthalene sulfonate was used as the supporting electrolyte was described. However, the conductive polymer was given a desired electric / electrical conductivity and substantially dedoped in the operating temperature range. Other materials may be used as long as they are not, and the present invention is not limited to the kind.

[0051]

[Table 1]

[0052]

As described above, the present invention includes a conductive polymer layer on at least one electrode of a capacitor having an electrode via a dielectric layer, and at least one layer covering the conductive polymer layer is provided. The present invention provides a capacitor having a structure in which at least one metal layer covering at least one of the metal layer and the conductive polymer layer is further disposed, and a method for producing the same. By preventing diffusion and permeation of the conductive polymer layer into the conductive polymer layer and suppressing deterioration of the conductive polymer layer, there is little deterioration in capacity, loss and high frequency impedance characteristics even under high temperature and high humidity, and excellent reliability. It is possible to realize a small-sized and large-capacity capacitor having

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a capacitor in which a conductive polymer layer used for one electrode is covered with a plurality of metal layers in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a capacitor in which a conductive polymer layer used for both electrodes is covered with a plurality of metal layers in another embodiment of the present invention.

FIG. 3 is a sectional view showing an example of a conventional capacitor using a conductive polymer for one electrode.

[Explanation of symbols]

 1 Electrode 2 Dielectric Layer 3 Conductive Polymer Layer 4a Metal Layer 4b Metal Layer 5a Electrode Lead 5b Electrode Lead 6 Insulating Resin Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigenari Nanai 3-10-1 Higashisanda, Tama-ku, Kawasaki-shi, Kanagawa Matsushita Giken Co., Ltd.

Claims (7)

[Claims] 1. At least one electrode of a capacitor having an electrode via a dielectric layer includes a conductive polymer layer, at least one metal layer covering at least a part of the conductive polymer layer, and further A capacitor in which at least another metal layer covering a part or the whole of a conductive polymer layer is arranged. 2. The repeating unit of the conductive polymer is pyrrole,
The capacitor according to claim 1, which is selected from hetero member ring compounds containing at least one of thiophene and derivatives thereof. 3. The dielectric layer is an oxide of a valve metal.
The listed capacitors. 4. The capacitor according to claim 3, wherein the valve metal is one selected from aluminum and tantalum. 5. A capacitor in which a conductive polymer layer is formed by electrolytic polymerization through a dielectric layer, and at least a part of the conductive polymer layer is coated to form at least one metal layer by plating. Production method. 6. The method for manufacturing a capacitor according to claim 5, wherein the plating is performed by electrolytic plating or electroless plating. 7. A repeating unit of a conductive polymer is pyrrole,
The method for manufacturing a capacitor according to claim 5, wherein the compound is selected from the group consisting of thiophene and heterocyclic compounds containing at least one of these derivatives.