JP2011192949A - Laminated type conductive polymer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To significantly reduce the cost of a laminated type conductive polymer capacitor so as to be competitive, by solving the problem wherein a winding-type solid electrolytic capacitor using a conductive polymer is now able to satisfy the demand for low price due to rapid cost reduction in ethylenedioxythiophene, while a laminated type conductive polymer capacitor uses a silver paint for laminate bonding, and it is considered that there is no room for cost reduction. <P>SOLUTION: A laminated type conductive polymer capacitor is configured, in a manner such that a material mainly composed of a high-conductivity distributed conductive polymer is used for laminate bonding instead of a silver paint, and consequently, it is possible to achieve significant cost reduction, while maintaining superior high-frequency characteristics. It is also possible to have the colloidal graphite layer interposed between a polymerization conductive polymer layer 3 to be used for internal filling and the distributed conductive polymer to be used for lamination. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a stacked solid electrolytic capacitor using a conductive polymer as a cathode conductive layer, a so-called stacked conductive polymer capacitor. In particular, a conductive polymer dispersed in a liquid is formed by using a valve metal foil having an anodized film formed on the surface of the surface as an anode, forming a cathode conductive layer by electrolytic polymerization on the surface of the anodized film The present invention relates to a laminated type conductive polymer capacitor that is laminated and bonded using the above. In addition, the present invention includes a colloidal graphite layer provided between an electropolymerized conductive polymer layer and a conductive polymer layer obtained from a conductive polymer dispersed in the liquid upon lamination.

  In general, a conjugated double bond conductive polymer represented by polyaniline, polypyrrole or polythiophene can be produced by chemical oxidative polymerization and electrolytic polymerization. When the electropolymerization is used, the conductive polymer is formed on the electrode in a uniform film shape, which is suitable for use as an electronic device.

  Patent Document 1 discloses a conductive polymer capacitor in which electrolytically polymerized polypyrrole is actually formed on the surface of an etched aluminum foil on which an anodized film is formed via a manganese dioxide layer.

The cathode is taken out by sequentially forming a colloidal graphite layer and a silver paint layer on the electropolymerized polypyrrole layer. This is the same traditional cathode formation method as a tantalum solid electrolytic capacitor using manganese dioxide as the cathode conductive layer.
A multilayer conductive polymer capacitor using electropolymerized polypyrrole as a cathode conductive layer is disclosed in Patent Document 2. This consists of preparing a plurality of capacitor elements in which an electropolymerized polypyrrole layer is formed via a manganese dioxide layer on the etched aluminum foil surface on which the anodized film is formed, and colloidal graphite layers and silver paint are formed on the conductive polymer surface of each element. A layered conductive polymer capacitor is manufactured by providing layers.

The multilayer conductive polymer capacitor thus obtained is characterized by extremely excellent high-frequency characteristics because the cathode is taken out with a silver paint layer having a small size, large capacity and high electrical conductivity. .
A cross-sectional view of a conventional aluminum laminated conductive polymer capacitor is shown in FIG. Although the case of stacking three sheets is shown, there may be a case where the number of stacked layers is actually increased as necessary. An alumina coating 2 is formed on the etched aluminum anode foil surface 1 by anodic oxidation, and an in situ polymerized conductive polymer layer 3 is formed on the surface. In the case of an aluminum capacitor, it is often an electropolymerized polypyrrole, but a chemically polymerized polyethylene dioxythiophene layer may be formed. Thereafter, the silver paint 5 is laminated and bonded through the colloidal graphite layer 4.
The problem of this manufacturing method is that the silver paint layer is expensive.

On the other hand, a conductive polymer capacitor in which chemically polymerized polyethylene dioxythiophene is formed on an aluminum capacitor element in which an anode foil and a cathode foil are wound via a separator has also been developed as a large capacity capacitor. This is disclosed in Patent Document 3, for example.
Although silver paint is not used here, there exists a subject that ESR (equivalent series resistance) cannot be made low because a separator exists between positive and negative electrodes. There was also a problem that ethylenedioxythiophene was expensive, but with the expiration of the patent of Patent Document 1, the number of participating manufacturers increased and the price declined rapidly, and this problem is being overcome.

Further, in the tantalum solid electrolytic capacitor, as shown in FIG. 2, a conventional block-shaped sintered body is used for the capacitor element. Although omitted in FIG. 2, the tantalum sintered body 6 having a chemical conversion film and an in-situ polymerized conductive polymer layer sinters fine tantalum powder, forms a tantalum dielectric film on this surface, and further An in situ polymerized conductive polymer layer 3 is formed thereon. On top of that, a silver paint layer 5 is formed via a colloidal graphite layer 4 to form a cathode. The anode lead 7 is a tantalum wire, but a tantala dielectric layer 8 is also formed on a part thereof. Since this sintered body type capacitor has a capacity drawn from the deep part of the sintered body, the conductive path becomes long, and even when a conductive polymer is used, it is difficult to sufficiently reduce ESR.
As shown in FIG. 3, a tantalum sintered body is thinly formed to form a manganese dioxide layer 9 inside the sintered body and manganese dioxide 10 on the surface of the sintered body, and the thin sintered body capacitor element is made of colloidal graphite 4 and Proposals have been made to improve frequency characteristics by laminating a plurality of sheets using silver paint 5. In this case, although the high-frequency characteristics are improved, there is a problem that the price increases due to an increase in the amount of silver paint.
As disclosed in Patent Document 4, a capacitor using polyethylenedioxythiophene as a cathode conductive layer was filed in 1989, but the period expired in 2009. Along with this, many manufacturers have entered the ethylenedioxythiophene supply, and the price has been drastically decreasing. This conductive polymer is used in a wound aluminum conductive polymer capacitor, and the capacitor price is rapidly decreasing under the influence.

  Furthermore, the electrical conductivity of the conductive polymer obtained by dispersing a complex of polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) in water and volatilizing the medium is increased to 1000 S / cm. It has been announced that This is disclosed in Non-Patent Document 1, for example. If such a conductive polymer having high electrical conductivity is used instead of expensive silver paint, a multilayer solid electrolytic capacitor having excellent high frequency characteristics can be realized.

Japanese Unexamined Patent Publication No. 01-310529 Japanese Patent Laid-Open No. 06-124858 Japanese Patent Laid-Open No. 10-310829 Japanese Patent Laid-Open No. 02-15611

http: // techon. nikkeibp. co. jp / article / NEWS / 20090629/172378 / A polymer film having a conductivity of 1000 S / cm was obtained from German H.C. C. Starck ships sample (June 29, 2009)

  A multilayer conductive polymer capacitor made by laminating etched aluminum foil using polypyrrole, which is an inexpensive monomer raw material, is expensive due to the use of silver paint mixed with silver powder in the binder of each capacitor element foil was there.

  On the other hand, in a wound aluminum conductive polymer capacitor using polyethylene dioxythiophene, the amount of polyethylene dioxythiophene filled between the positive and negative electrodes through a separator layer is smaller than that of a tantalum conductive polymer capacitor. Since the price of ethylenedioxythiophene monomer, which is relatively expensive, is difficult to reduce the price of the capacitor, there has never been a large price difference between the two.

  However, as mentioned above, with the expiration of the patent for capacitors using polyethylene dioxythiophene, the price of ethylenedioxythiophene monomer has dropped significantly, and laminated aluminum conductive polymer using electropolymerized polypyrrole and silver paint Capacitors are becoming less expensive.

  Since the tantalum conductive polymer capacitor has a large capacity and a small volume, the amount of the conductive polymer and silver paint to be used is small. However, the frequency characteristics are low because the tantalum powder is expensive and the ESR (equivalent series resistance) of the cathode conductive layer cannot be made as small as in the case of the aluminum conductive polymer capacitor because of the structure of using the block-like electrode. Somewhat inferior.

  The present invention solves the above-mentioned problems of the prior art, and is a laminated type conductive polymer capacitor that is excellent in high-frequency characteristics and inexpensive by laminating a plate type capacitor in which an in-situ polymerized conductive polymer is formed on a cathode conductive layer. Is intended to provide.

  According to the first aspect of the present invention, there is provided a conductive polymer dispersed in a liquid, wherein a dielectric coating and a cathode conductive layer are formed on the surface of a foil-like valve metal with an in-situ polymerized conductive polymer. A laminated conductive polymer capacitor in which the above-mentioned dielectric coating and each foil-shaped valve metal with a cathode conductive layer formed using a conductive polymer as a main component are provided at low cost because silver paint is not used. It is a feature that can be done.

  The invention according to claim 2 of the present invention is a laminated conductive polymer capacitor whose in-situ polymerization is electrolytic polymerization or chemical polymerization, and has a feature that a low ESR capacitor can be provided at low cost.

  The invention according to claim 3 of the present invention is a laminated conductive polymer capacitor characterized in that the in-situ polymerized conductive polymer is polypyrrole or a derivative thereof, polythiophene or a derivative thereof, and a capacitor having a low ESR. Can be provided at low cost.

  The invention according to claim 4 of the present invention is a multilayer conductive polymer capacitor in which the conductive polymer dispersed in the liquid is a kind selected from those mainly composed of polyethylenedioxythiophene, and has a low ESR. The capacitor can be provided at a low cost. The conductive polymer layer dispersed in the liquid may include a binder for facilitating the lamination of individual capacitor elements.

  The invention according to claim 5 of the present invention is a laminated conductive polymer capacitor in which the foil-shaped valve metal is any one of an etched aluminum foil, a tantalum sintered thin film or a niobium sintered thin film, and has a low ESR. The capacitor can be provided at low cost.

  The invention according to claim 6 of the present invention is a multilayer conductive polymer capacitor having a structure in which each foil-like valve metal electrode has an anode terminal and the anode terminal is electrically joined, and has a low ESR. The capacitor can be provided at low cost.

  According to the seventh aspect of the present invention, a dielectric coating and a cathode conductive layer are formed on the surface of a foil-like valve metal with an in-situ polymerized conductive polymer, and further dispersed in a liquid via a colloidal graphite layer. A laminated type conductive polymer capacitor in which the respective foil-like valve metals on which the dielectric coating and the cathode conductive layer are formed are laminated using the conductive polymer layer. By interposing the colloidal graphite layer, the adhesion between the in-situ polymerized conductive polymer layer and the conductive polymer layer dispersed in the liquid is improved, and a higher effect is obtained for improving the ESR.

  The invention according to claim 8 of the present invention is the laminated conductive polymer capacitor according to claim 7, wherein the in-situ polymerization is electrolytic polymerization or chemical polymerization, and has a feature that a low ESR capacitor can be provided at low cost. .

  The invention according to claim 9 of the present invention is the multilayer conductive polymer capacitor according to claim 7 or 8, wherein the in-situ polymerized conductive polymer is polypyrrole or a derivative thereof, polythiophene or a derivative thereof, and has a low ESR. The capacitor can be provided at low cost.

  The invention according to claim 10 of the present invention is one in which the conductive polymer dispersed in the liquid is one selected from those mainly composed of polyethylenedioxythiophene. It is a molecular capacitor and has a feature that a low ESR capacitor can be provided at low cost.

  The invention according to claim 11 of the present invention is the laminated conductive polymer capacitor according to any one of claims 7 to 10, wherein the foil-shaped valve metal is an etched aluminum foil, a tantalum sintered thin film or a niobium sintered thin film. The low ESR capacitor can be provided at low cost.

  The invention according to claim 12 of the present invention is the laminated conductive polymer according to any one of claims 7 to 11, wherein each foil-shaped valve metal electrode has an anode terminal, and the anode terminal is electrically joined. The capacitor is characterized in that a low ESR capacitor can be provided at low cost.

  Conductive film mainly composed of conductive polymer dispersed in a liquid with high electrical conductivity without using silver paint. Since the polymer is laminated, a low ESR multilayer conductive polymer capacitor can be obtained at a low cost. Furthermore, by providing a colloidal graphite layer between the in-situ polymerized conductive polymer layer and a conductive polymer layer mainly composed of a conductive polymer dispersed in a liquid having high electrical conductivity, In addition, the present invention has a feature that it can improve the adhesiveness of the resin, and can provide a conductive polymer capacitor having a low ESR.

Sectional view showing a conventional laminated aluminum solid electrolytic capacitor structure using a conductive polymer for the cathode conductive layer Sectional view showing a conventional tantalum sintered solid electrolytic capacitor structure using a conventional conductive polymer for the cathode conductive layer Sectional view showing a conventional multilayer tantalum sintered solid electrolytic capacitor structure using conventional manganese dioxide as the cathode conductive layer Sectional drawing which shows the laminated aluminum solid electrolytic capacitor structure which used the conductive polymer in Example 1 of this invention for the cathode conductive layer Sectional drawing which shows the laminated aluminum solid electrolytic capacitor structure which used the conductive polymer in Example 2 of this invention for the cathode conductive layer Sectional drawing which shows the laminated type tantalum sintered compact solid electrolytic capacitor structure which used the conductive polymer in Example 3 of this invention for the cathode conductive layer Sectional drawing which shows the laminated type tantalum sintered compact solid electrolytic capacitor structure which used the electroconductive polymer in Example 4 of this invention for the cathode conductive layer Sectional drawing which shows the structure of the capacitor | condenser element which formed the cathode conductive layer which consists of a conductive polymer on the aluminum foil in Example 1 of this invention

  Embodiments of the present invention will be described below with reference to the drawings. Although typical examples of the present invention are described in the examples, the present invention is not limited to the embodiments of the present invention.

  FIG. 8 is a cross-sectional view showing the structure of the capacitor element of the first embodiment.

  The capacitor element was affixed with a polyimide adhesive tape 12 having a width of 1 mm across both sides so as to partition the etched aluminum anode foil 1 having a length of 8 mm and a width of 3.5 mm into 4 mm and 3 mm portions in the length direction. .

  Next, electricity was applied from a 3 mm long portion of the etched aluminum anode foil 1, and a constant voltage of 3 V was applied to the 4 mm long portion using a 3% ammonium adipate solution at 70 ° C. An alumina dielectric coating 2 was formed. The capacitance of the capacitor element at this time was measured in the chemical conversion solution and found to be 20 μF. Thereafter, it was washed with deionized water and dried.

  Next, a 4 mm long portion of etched aluminum anode foil 1 was immersed in a 30% aqueous manganese nitrate solution and heated to 250 ° C. to form a pyrolytic manganese dioxide layer (not shown).

Next, a stainless steel polymerization start electrode is brought into contact with the polyimide adhesive tape, immersed in a polymerization positive electrolyte containing 0.3M pyrrole monomer and 0.1M sodium naphthalene sulfonate, and separately separated in the polymerization solution. Electropolymerization was performed by applying a DC voltage of 3 V between the provided cathode and the in-situ polymerized conductive polymer layer 3 made of polypyrrole was formed on the spot. PEDOT (polyethylenedioxythiophene) / PPS (polystyrene sulfonic acid) dispersion in which 5% of dimethyl sulfoxide (DMSO) is added to the in-situ polymerized conductive polymer layer 3 of this device (CLEVIOS manufactured by HC Stark) ^TM PH750) was added with 1 part by weight of a binder made of modified polyethylene terephthalate, and this was applied and laminated and bonded as shown in FIG. At the same time, an anode lead (not shown) was attached at the same time to produce 10 aluminum foil laminated solid electrolytic capacitors, and a capacity of 1 kHz, tan δ, and an equivalent series resistance (ESR) of 100 kHz were measured. Their average values are shown in (Table 1).

(Comparative Example 1)
Next, in the same manner as in Example 1, except that a carbon layer was formed on the in-situ polymerized conductive polymer layer 3 by Aquadug and laminated using silver paint Unimec H9430S (Namics). Ten laminated aluminum solid electrolytic capacitors were manufactured and evaluated in the same manner as in Example 1. The results are shown in (Table 1).

  From these comparisons, there was almost no difference in the characteristics of the obtained multilayer aluminum solid electrolytic capacitor, and the multilayer aluminum solid electrolytic capacitor of the present invention did not use silver, so it was possible to significantly reduce the cost. . This is because the electric conductivity of the conductive polymer mainly composed of PEDOT / PSS used for lamination is as high as about 750 S / cm.

  Ten capacitors as shown in FIG. 5 were produced in the same manner as in Example 1 except that the colloidal graphite layer 4 was provided on the in-situ polymerized conductive polymer 3 in Example 1 above. The same evaluation was performed. The results are shown in (Table 1).

  In Example 2, by providing the colloidal graphite layer 4, the capacity, tan δ, and ESR tend to be improved, although slightly. This is achieved by interposing a colloidal graphite layer 4 and an in situ polymerization conductive polymer layer 3. It is considered that the adhesion and covering properties of the dispersion-type conductive polymer layer 10 are improved.

  In the case where the in-situ polymerized conductive polymer 3 is an electropolymerized polypyrrole, since a flat and dense film is formed, the effect of interposing the colloidal graphite layer 4 is not noticeable. The polymer 3 can also be formed by chemical polymerization, in which case a powdered conductive polymer layer is formed, and the adhesion / coverability is improved by interposing the colloidal graphite layer 4, and the effect is improved. It appears greatly. Note that although the case where a dispersive conductive polymer is used for the lamination is described here, a soluble conductive polymer can be used as long as the conductivity is similarly high.

  First, a thin tantalum sintered body element with a tantalum lead of 0.33 mm × 2.1 mm × 1.6 mm was prepared. The lead wire was drawn out from a portion having a small area in the plan view. To this tantalum sintered body, an tantalum dielectric coating 8 was formed by anodic oxidation using an electrolytic solution in which 5 ml of phosphoric acid was dissolved in 1000 ml of deionized water and applying 18 V at about 90 ° C. Thereafter, it was washed with deionized water and dried at 105 ° C. The capacity at this time was measured in 2N sulfuric acid and found to be 42 μF.

Thereafter, an in-situ polymerized electrolytic polymer film 3 was formed in the same manner as in Example 1 to complete the capacitor element. Further, similarly to Example 1, a laminated tantalum solid electrolytic capacitor was produced by laminating three sheets using the dispersed conductive polymer layer 10.
This sintered body was immersed in a solution of ethylenedioxythiophene: p-toluenesulfonic acid ferric acid: methanol: 18: 10: 10 (weight ratio) and then heated at 80 ° C. for 1 hour to obtain polyethylenedioxythiophene. A layer was formed inside and then washed with ethanol. This operation was repeated until the inside and the surface were filled with the conductive polymer.

  As shown in FIG. 6, this thin tantalum sintered body element is laminated using the same dispersion type conductive polymer as in Example 1, and 10 anodes of laminated tantalum solid electrolysis are attached by attaching anode leads (not shown). The capacitor was completed. This capacitor was measured in the same manner as in Example 1, and the results are shown in (Table 1).

(Comparative Example 2)
In Example 3, 1.3 mm × 2.1 mm × 1.6 mm tantalum sintered instead of a thin tantalum sintered body with a tantalum lead of 0.33 mm × 2.1 mm × 1.6 mm as shown in FIG. Ten tantalum solid electrolytic capacitors were prepared in the same manner as in Example 3, except that the silver paint layer 5 was formed by using the ligature and further laminating the colloidal graphite layer 4 in the same manner as in Example 2. Their characteristics are shown in (Table 1).

  Since the capacitor of Comparative Example 2 is not laminated, it is difficult to form the in-situ polymerized conductive polymer layer 3 in the deep part, and the capacitance is low. Further, since tan δ and ESR tend to increase due to the large thickness, the resistance to drawing from the deep portion is large. The multilayer tantalum solid electrolytic capacitor according to the present invention is inexpensive because it does not use expensive silver paint, and because it uses thin foil-like tantalum sintered body, it uses a conventional block electrode. Compared to the above, a capacitor having excellent high frequency characteristics can be obtained.

  In Example 3, a laminated tantalum solid electrolytic capacitor shown in FIG. 7 was produced in the same manner as in Example 3 except that the colloidal graphite layer 4 was interposed, and the same evaluation as in Example 1 was performed. The results are shown in (Table 1). By interposing the colloidal graphite layer 4, the in-situ polymerized conductive polymer layer 3 and the dispersive conductive polymer layer 11 are improved in adhesion and covering properties, and further increase in capacity and decrease in tan δ and ESR. It is clear that is realized.

In the examples, only the case of using electropolymerized polypyrrole and the case of using chemically polymerized polyethylene dioxythiophene as the in-situ polymerized conductive polymer were described, but other conductive polymers may be used, and the present invention It is not limited to those types. In the embodiments, only the case where PEDOT / PSS is the main component as the dispersive conductive polymer has been described, but the present invention is not limited to that type.
It is also possible to use a material in which polypyrrole is dispersed. It is easily assumed that the same result can be obtained when niobium is used as the anode valve metal.

  Since the multilayer solid electrolytic capacitor according to the present invention is laminated with an adhesive mainly composed of a highly conductive conductive polymer, instead of expensive silver paint, it is inexpensive and has excellent high-frequency characteristics. Can be realized. In particular, the patent disclosed in Japanese Patent Laid-Open No. 01-310529 expired in 2009, and the cost of ethylene dioxythiophene monomer and ferric p-toluenesulfonate as an oxidizing agent has been drastically reduced. The price of wound aluminum solid electrolytic capacitors using a conductive polymer is decreasing. The conventional laminate type had a problem that it was relatively expensive because it was bonded with silver paint. However, the dispersion type conductive polymer with high electrical conductivity represented by PEDOT / PSS to which DMSO was added was applied to silver paint. By using it instead of a layer, it is possible to realize a significant cost reduction with almost no deterioration in characteristics, and industrial applicability is extremely high.

  Furthermore, after that, distributed PEDOT / PSS exceeding 1000 S / cm has been developed in Germany. C. Sample shipments from Starck were announced on June 29, 2009. On March 16, 2009, Sanyo Electric Co., Ltd. announced PEDOT / PSS having electrical conductivity reaching 1400 S / cm. By using these as the main material of the laminating adhesive, it is expected that a laminar solid electrolytic capacitor having further excellent high frequency characteristics can be realized at low cost, and industrial applicability is further increased.

Claims (12)

    Forming a dielectric coating on the surface of the foil-shaped valve metal and a cathode conductive layer with an in-situ polymerized conductive polymer, and using the conductive polymer layer mainly composed of a conductive polymer dispersed in a liquid A laminated conductive polymer capacitor in which each foil-like valve metal on which a dielectric coating and a cathode conductive layer are formed is laminated.     The laminated conductive polymer capacitor according to claim 1, wherein the in-situ polymerization is electrolytic polymerization or chemical polymerization.       3. The laminated conductive polymer capacitor according to claim 1 or 2, wherein the in-situ polymerized conductive polymer is polypyrrole or a derivative thereof, polythiophene or a derivative thereof.     4. The laminated conductive polymer capacitor according to claim 1, wherein the conductive polymer dispersed in the liquid is mainly composed of polyethylene dioxythiophene.     5. The laminated conductive polymer capacitor according to claim 1, wherein the foil-shaped valve metal is an etched aluminum foil, a tantalum sintered thin film or a niobium sintered thin film.     6. The multilayer conductive polymer capacitor according to claim 1, wherein each foil-like valve metal electrode has an anode terminal and the anode terminal is electrically joined.     A conductive film composed mainly of a conductive polymer dispersed in a liquid via a colloidal graphite layer is formed by forming a dielectric coating on the surface of the foil-shaped valve metal and a cathode conductive layer with an in-situ polymerized conductive polymer. A laminated conductive polymer capacitor in which each foil-like valve metal on which the dielectric coating and the cathode conductive layer are formed is laminated using a molecular layer.     The multilayer conductive polymer capacitor according to claim 7, wherein the in-situ polymerization is electrolytic polymerization or chemical polymerization.   The multilayer conductive polymer capacitor according to claim 7 or 8, wherein the in-situ polymerized conductive polymer is polypyrrole, a derivative thereof, polythiophene, or a derivative thereof.     10. The multilayer conductive polymer capacitor according to claim 7, wherein the conductive polymer dispersed in the liquid is one selected from those mainly composed of polyethylene dioxythiophene.     11. The laminated conductive polymer capacitor according to claim 7, wherein the foil-shaped valve metal is an etched aluminum foil, a tantalum sintered thin film or a niobium sintered thin film.     12. The laminated conductive polymer capacitor according to claim 7, wherein each foil-like valve metal electrode has an anode terminal, and the anode terminal is electrically joined.

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