TW201432751A - Solid electrolytic capacitor - Google Patents

Abstract

The purpose of the present invention is to reduce the ESR of a solid electrolytic capacitor. The present invention is a solid electrolytic capacitor in which are formed on the surface of an anode comprising a metal, in this order, a dielectric oxide coating layer, a solid electrolyte layer, a conductive carbon layer, and a cathode leadout layer, wherein the conductive carbon layer contains at least 0.5 weight percent of graphene and/or nanographene. Due to the conductive carbon layer containing graphene and/or nanographene, the electrical conductivity of the conductive carbon layer is reduced, and a low ESR can be achieved for the solid electrolytic capacitor.

Description

Solid electrolytic capacitor

The present invention relates to a solid electrolytic capacitor, and more particularly to a solid electrolytic capacitor used in a high frequency circuit for supplying power to a CPU.

Conventionally, as an electrolytic capacitor, a valve metal such as aluminum or ruthenium is used as an anode body, and an electrolytic solution or a solid electrolyte is used as a capacitor of a true cathode electrolyte.

In recent years, the drive circuit of the CPU particularly requires low drive voltage, low power consumption, high frequency correspondence, etc., and therefore, the capacitor is also required to have a larger capacitance and a lower series equivalent resistance ( Hereinafter, the series equivalent resistance is referred to as ESR) and the lower series equivalent inductance (hereinafter, the series equivalent inductance is referred to as ESL). In response to such a request, in particular, for the purpose of low ESR, a conductive polymer having high conductivity was used as a solid electrolyte of an electrolytic capacitor, and development thereof was carried out.

Here, the structure of the electrolytic capacitor using the conventional conductive polymer as a solid electrolyte will be described with reference to FIG. 3 . Figure 3 is A cross-sectional view showing a configuration of an electrolytic capacitor in which a conventional conductive polymer is used as a solid electrolyte. In Fig. 3, 31 is an electrode (aluminum electrode body for an anode), 32 is a dielectric oxide film layer, 33 is a solid electrolyte layer, 34 is a conductive carbon layer, 35 is a silver coating layer, and 36 is a cathode terminal. The cathode lead. In the solid electrolytic capacitor of such a configuration, the silver coating layer 35 constitutes a cathode extraction layer.

As shown in FIG. 1, the anode is made of the surface of the aluminum electrode body 31. The roughening treatment is performed, and a dielectric oxide film layer 32 is formed on the surface. The surface of the aluminum electrode body 31 for an anode provided with the dielectric oxide film layer 32 on the surface thereof is formed of a solid polymer made of a conductive polymer such as polypyrrole, polythiophene, polyaniline or a derivative thereof. Electrolyte layer 33. Further, on the solid electrolyte layer 33, a capacitor element is formed which is sequentially formed with a conductive carbon layer 34 and a silver coating layer 35. For the capacitor element, an anode terminal (not shown) is connected to the anode aluminum electrode body, the cathode lead 36 is connected to the silver coating layer 35, and further, if necessary, a mold resin is used for external electrical connection. A capacitor element is packaged to form a conventional solid electrolytic capacitor.

Such a conventional conductive polymer as a solid electrolyte The solid electrolytic capacitor has a characteristic that its ESR is lower than that of an electrolytic capacitor using an electrolytic solution as an electrolyte and a solid electrolytic capacitor using manganese dioxide and TCNQ (tetracyanoquinodimethane) as a solid electrolyte. This is because the conductivity of the conductive polymer is higher than that of the conventional electrolyte, manganese dioxide, TCNQ, etc., and the use of the conductive polymer as a solid electrolyte solid electrolytic capacitor, and the use of the conventional electricity Compared with a solid electrolyte capacitor that is desolved, a reduction in ESR can be achieved.

However, as the CPU's high frequency action, as a power supply The source electrolytic capacitor is also required for further low ESR. Here, the structure of the electrolytic capacitor is reviewed, and various materials constituting the solid electrolyte layer 33, the conductive carbon layer 34, and the silver coating layer 35 are examined.

Among them, a conductive polymer is formed on the surface of the anode body In the solid electrolytic capacitor of the formed solid electrolyte layer, since the solid electrolyte layer is electrically connected to the external electrode, a conductive carbon layer and a silver coating layer are generally formed on the upper surface of the solid electrolyte layer.

Conductive carbon layer as such a solid electrolytic capacitor The required characteristics are such that the adhesion to the solid electrolyte layer is high, and the internal resistance inside the conductive carbon layer is required to be low. Therefore, in order to satisfy such a characteristic, it is known to use graphite which is relatively large (Patent Document 1), and carbon particles having a small particle diameter such as carbon black are used (Patent Document 2), and further, Carbon tube (Patent Document 3).

Moreover, mixing these carbon materials is also a common hand for users. segment. The reason for mixing such a carbon material to form a conductive carbon layer will be as follows. That is, in the case where the conductive carbon layer is formed only by the carbon particles having a small particle diameter, the contact area with the solid electrolyte layer is increased, and it is suitable for reducing the interface contact resistance with the solid electrolyte layer. . On the other hand, when a conductive carbon layer is formed only from carbon particles having a small particle diameter, in order to form a conductive carbon layer having a certain thickness, the thickness of the conductive carbon layer is often changed to carbon particles, and carbon particles are present. The interface contact resistance between each other becomes large. Therefore, when only a carbon particle having a small particle diameter is used to form a conductive carbon layer, the interfacial contact resistance with the solid electrolyte layer is reduced, but the internal resistance of the inside of the conductive carbon layer is increased. Get a full ESR reduction effect.

Here, it is necessary to mix carbon materials with a larger particle size to reduce The internal resistance of the less conductive carbon layer. When carbon materials of different particle diameters are mixed, the carbon particles having a smaller particle diameter reduce the interface contact resistance with the solid electrolyte layer, and the conductive carbon layer has a carbon material having a larger particle diameter, thereby reducing the conductivity. The frequency of contact between the carbon particles inside the carbon layer reduces the internal resistance. As a result, the entire internal resistance can be reduced as a whole of the conductive carbon layer functioning as an electrode pulled out from the solid electrolyte layer.

As such a carbon material having a large particle size, it is known that The flaky graphite of natural graphite, which is mostly used in a size of about 0.1 to 50 μm. Further, as the carbon element having a small particle diameter, carbon black is known, and it is also known that it is particularly preferable to use a high conductivity Ketchen black.

Further, in Patent Document 3, it is disclosed in such a guide The electric carbon layer contains a carbon nanotube, whereby the adhesion to the solid electrolyte layer can be improved, and the deterioration of ESR over time can be suppressed.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. Hei 2-265234

Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-79838

Patent Document 3: Japanese Laid-Open Patent Publication No. 2003-86464

However, even if a conventional carbon material such as graphite or carbon black is combined at various ratios to form a carbon layer, it is difficult to further reduce the ESR of the solid electrolytic capacitor.

The present invention has been made in order to solve the above-described problems of the prior art, and an object of the present invention is to further reduce the ESR of a solid electrolytic capacitor.

In order to solve the above problems, the invention described in claim 1 is a solid electrolytic capacitor in which a dielectric oxide film layer, a solid electrolyte layer, and a conductive layer are sequentially formed on a surface of an anode body made of a metal material having a valve action. A solid electrolytic capacitor of a carbon layer and a cathode lead layer, characterized in that the conductive carbon layer contains graphene and/or nanographene.

Here, the term "graphene" means a carbon atom bonded to a thickness of 1 atom SP ² to form a carbon atom having a two-dimensional hexagonal lattice structure. Further, the term "nano graphene" refers to a structure in which the graphene is laminated into a plurality of layers, and has a thickness of approximately 10 to 1000 nm.

Each layer of graphite is an ABA layer or a structure called a Benel layer. In this configuration, the electron band structure of the two layers is close to the two sets of electrons. The hole can be made with a hole. Having such an electronic band structure When the laminated layer has a plurality of layers, a part of the energy band is doped with electrons and a part is doped with a hole by interlayer interaction. It is said that the graphite is called a metalloid because the electron doping increases the electrical resistance.

On the other hand, nanographene, which is graphene-laminated In the structure, there is a structure called an ABC laminate. In this configuration, unlike the above-described structure of the ABA laminate of graphite, that is, the AB-AB-AB... continuous laminate, the structure of the C layer exists between the AB laminates. The C layer has the original electron band structure of graphene, and there is no interlayer interaction (or weak interaction) from the adjacent layers, so there is no part of the band doping electrons, a part of the doping Hole (or the number is very rare). It is said that this does not increase the resistance.

In this way, graphene, nanographene and general graphite phase Its conductivity is extremely high. As such graphene and nano graphene, about 50 layers of nanographene are commercially available. Further, the aspect ratio of the commercially available nanographene (thickness of the nanographene: area) is about 1:10 to 1:1000. However, the invention of the present invention is not limited to such nanographenes, as long as it has an electron band structure of graphene and has a high electrical conductivity from a graphene structure, an aspect ratio of graphene, nanographite. The aspect ratio or the number of layers of the olefin can be arbitrarily selected.

As described above, graphene and nanographene have come High conductivity from its construction. Therefore, the conductive carbon layer can reduce the electric resistance of the conductive carbon layer by containing graphene and/or nanographene, and can realize low ESR as a solid electrolytic capacitor.

Then, the content of graphene and/or nanographene is The weight ratio of the entire solid content of the conductive carbon layer to be formed is preferably 0.5% by weight or more. Usually, in order to form a conductive carbon layer, a coating material containing a carbon material is applied, and the dispersion medium is dried to form a conductive carbon layer. In the present invention, the weight ratio of the coating agent for forming the conductive carbon layer is not defined, but the weight ratio of the state in which the dispersion medium is evaporated after the coating agent is dried is defined. In other words, it is a weight ratio of a solid component (nonvolatile component) contained in a coating agent for forming a conductive carbon layer.

Further, when graphite is used as the carbon material, it is also considered that graphene and/or nanographene are formed in the pulverization process of graphite. Moreover, there are reports that graphite contains about 10% of graphene electron band structures. However, in the present invention, the graphene electron band structure originally present in the graphite or the graphene and/or nanographene contained in the graphite material is formed in the graphite manufacturing process. As part of the graphite material. Therefore, the content of the weight of the solid component constituting the conductive carbon is calculated based on the amount of the graphite material or the like added as graphene and/or nanographene.

The content of graphene and/or nanographene is set to 0.5% by weight or more based on the total weight of the solid component forming the conductive carbon layer, thereby obtaining the effect of reducing the ESR of the solid electrolytic capacitor. If the content is less than 0.5% by weight, the ESR characteristics of the solid electrolytic capacitor do not vary too much. Further, as the content of graphene and/or nanographene, it has been observed that as the content thereof increases, the effect of lowering the ESR tends to increase. Graphene and/or nanographene on the other hand When the content of the coating agent is more than the quantitative setting, the viscosity of the coating agent rises, and the workability of the coating process of the coating agent is remarkably lowered. This operability depends on the total amount of graphite, carbon black, graphene and/or nanographene as a carbon material for an organic solvent, and the content of a resin further as a binder, and the ratios thereof are changed. Since the upper limit of the amount of addition of graphene and/or nanographene (the upper limit causing deterioration of workability) also changes, the upper limit of the amount of addition cannot be clearly defined.

According to the present invention, it is possible to provide a solid electrolytic capacitor which can reduce the ESR of a solid electrolytic capacitor and can supply electric charge excellently in a high frequency circuit.

1‧‧‧ capacitor components

2‧‧‧Connecting board

11‧‧‧Aluminum

12‧‧‧Dielectric oxide coating

13‧‧‧Solid electrolyte layer

14‧‧‧ Conductive carbon layer

15‧‧‧Silver coating

16‧‧‧ Cathode

17‧‧‧Anode

21‧‧‧Insert substrate

22‧‧‧Anode conductor

23‧‧‧Cathode conductor

24‧‧‧Anode conductor

25‧‧‧Cathode conductor

31‧‧‧Electrode body

32‧‧‧Dielectric oxide coating

33‧‧‧Solid electrolyte layer

34‧‧‧ Conductive carbon layer

35‧‧‧Silver coating

36‧‧‧Cathode lead

C‧‧‧Solid electrolytic capacitor

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing the structure of an example of a solid electrolytic capacitor according to the present invention.

Fig. 2 is a perspective view showing a mounting substrate used in an example of a solid electrolytic capacitor of the present invention.

3 is a cross-sectional view showing a conventional solid electrolytic capacitor.

The best form for implementing the invention

Hereinafter, with respect to the solid electrolytic capacitor of the present invention The embodiment (hereinafter, referred to as an embodiment) will be specifically described.

The shape of the solid electrolytic capacitor suitable for the present invention is not Particularly, for example, a solid electrolytic capacitor having the following configuration can be applied.

a solid electrolytic capacitor having a capacitor element, and The substrate is mounted on the inner surface of the concave portion formed in the center of the anode body formed by the valve action metal, and a dielectric oxide film layer, a solid electrolyte layer, and a cathode portion are sequentially formed, and around the concave portion The anode substrate is an anode portion, and the mounting substrate has a surface on which the capacitor element is mounted and a mounting surface facing the wiring board, and the surface on which the capacitor element is mounted is formed to correspond to the anode portion and the cathode portion of the capacitor element, respectively. The conductor has a cathode electrode and an anode electrode around the cathode electrode on the mounting surface facing the wiring substrate, and the conductor penetrates the inside and is electrically connected to the anode electrode and the cathode electrode, respectively.

Hereinafter, the structure of the solid electrolytic capacitor described above, An embodiment of the present invention will be described.

Figure 1 (a) is a view showing a solid electrolytic capacitor of the present invention In the cross-sectional view, (b) is a cross-sectional view showing the solid electrolytic capacitor being decomposed into a capacitor element and a mounted substrate.

The capacitor element 1 used in the present invention will be described together with Fig. 1(b). First, a thin plate-shaped aluminum material is used as the anode body 11, and a recess having a predetermined size is formed at the center of the anode body 11 by cutting, pressing, etching, or the like. Further, the inner surface of the concave portion is subjected to a surface expansion treatment by etching, and the dielectric oxide film layer is further formed by anodization. 12. Then, a solid electrolyte layer 13 made of a conductive polymer is formed on the dielectric oxide film layer 12 which becomes the inner surface of the concave portion of the cathode, and then a conductive carbon layer 14 and a silver coating layer are formed on the solid electrolyte layer 13. 15. The cathode portion 16 serves as the capacitor element 1. In the capacitor element 1, a portion around the concave portion of the anode body 11 serves as the anode portion 17.

Such a capacitor element 1 is an aluminum material of a starting material. The thickness is set to about 100 to 500 μm, the thickness of the etching layer is 20 to 30 μm, and the depth from the uppermost portion of the etching layer to the concave portion is about 15 to 50 μm, whereby a thin capacitor element can be manufactured.

The depth of the recess of the capacitor element 1 is formed to be Shallowly, the conductive distance from the dielectric oxide film layer 12 to the cathode portion 16 of the power source of the capacitor element is short, and the effect of reducing the ESL is preferable. However, a dielectric oxide film layer 12 is formed on the inner surface of the concave portion, and a solid electrolyte layer 13 and a cathode portion 16 (conductive carbon layer 14, silver coating) are sequentially formed on the dielectric oxide film layer 12. Layer 15), but it is necessary for the solid electrolyte layer 13 and the cathode portion 16 not to protrude from the concave portion. Therefore, even if the thickness of the solid electrolyte layer 13 is formed to a thickness of about 3 to 10 μm, and the thickness of the cathode portion 16 is formed to be about 10 to 15 μm, in order to prevent the protrusion from protruding from the concave portion, the depth of the concave portion must be 15~. About 50μm.

Moreover, in order to form the concave portion to a depth of about 15 to 50 μm The thickness of the aluminum material of the starting material needs to be about 100 μm. If it is thinner than this, when the concave portion is formed, the aluminum material 11 itself is deformed, and the strength of the anode body after the concave portion is formed becomes extremely weak.

However, even if it is made of aluminum having a thickness of 100 μm In the case of a capacitor element, it cannot be said that its strength must be strong enough. Here, in order to reinforce the strength of such a capacitor element, it is also possible to affix a steel material having a higher strength than aluminum to the opposing surface of the concave portion of the capacitor element. Further, the single side of the aluminum material may be anodized in advance to increase the strength.

Moreover, when the thickness of the aluminum material 11 is set to about 500 μm, Since sufficient strength can be ensured when the concave portion is formed, it is not necessary to increase the strength such as adhesion of the steel material or anodizing treatment.

In addition, among the capacitor elements, in the dielectric oxide film For the layer and the solid electrolyte layer, it is necessary to avoid the application of mechanical stress. If mechanical pressure is applied to the dielectric oxide film layer and the solid electrolyte layer, the dielectric oxide film is damaged, and there is a concern that the leakage current is increased. In addition, if mechanical pressure is applied to the solid electrolyte layer, there is a concern that the conductivity of the solid electrolyte layer is lowered. However, in the capacitor element, the dielectric oxide film layer and the solid electrolyte layer are formed inside the concave portion of the anode body and are surrounded by the anode body 11 to be protected.

(solid electrolyte layer)

The solid electrolyte layer 13 formed by the capacitor element 1 described above will be described.

The solid electrolyte layer 13 is formed of a conductive polymer, and as the conductive polymer, polythiophene, polypyrrole, polyaniline, and derivatives thereof are preferable. As a method of forming the solid electrolyte layer, a monomer and an oxidizing agent using the conductive polymer as a precursor can be used for chemical polymerization. A method of forming a solid electrolyte layer, a method of forming a solid electrolyte layer by electrolytically polymerizing a monomer, a conductive polymer dispersion obtained by dispersing fine particles of a conductive polymer at a predetermined position, and forming a solid by drying A method of forming an electrolyte layer, such as a method of forming a solid electrolyte layer made of a conductive polymer.

(conductive carbon layer)

A conductive carbon layer 14 is formed on the solid electrolyte layer 13 described above. The conductive carbon layer 14 is obtained by adding and mixing a predetermined amount of graphene and/or nanographene to a carbon material made of graphite or carbon black, a polyester resin as a binder, a phenol resin, an acrylic resin, or the like. The mixture is dispersed in a coating material made of an organic solvent, and the mixed coating material is applied onto the solid electrolyte layer 13 to form a conductive carbon layer after drying. As a coating material in which graphite, carbon black, and a polyester resin, a phenol resin, an acrylic resin, or the like as a binder are further dispersed in an organic solvent, a conductive carbon coating material in the field of solid electrolytic capacitors can be generally used. Further, the coating and drying process may be carried out by a method of forming a conductive carbon layer of a usual solid electrolytic capacitor. Further, as the material constituting the conductive carbon layer, a metal fine powder may be contained. The feature of the present invention is that the conductive carbon layer contains a specific amount of graphene and/or nanographene.

The carbon material constituting the conductive carbon layer 14 is not limited In the above graphite and carbon black. However, as a general conductive carbon layer, graphite and carbon black are often contained. The particle size of carbon black is about 3 to 500 nm, and the particle diameter is extremely small, and it is widely adhered to the solid electrolyte layer. Therefore, by carbon black The interface contact resistance between the solid electrolyte layer and the conductive carbon layer can be lowered, so that carbon black is preferably added. The content of the carbon black is preferably 5 to 20% by weight, and more preferably 10 to 16% by weight, based on the total weight of the solid component forming the conductive carbon layer. A decrease in ESR can be expected in this range. Further, as carbon black, it is preferably spherical. Further, the size of graphite is often used in a relatively large particle size of about 0.1 to 50 μm. The conductivity of graphite itself is lower than that of graphene and/or nanographene, but the particle size of graphite is large, so that the contact frequency of the carbon materials in contact with each other in the conductive carbon layer is reduced. Therefore, as a whole of the conductive carbon layer, the contact resistance between the carbon materials can be reduced. For this reason, it is preferred to add graphite. Further, graphene and/or nanographene having the same size as the particle diameter of carbon black or the particle diameter of graphite as described above are prepared, and graphene and/or nanographene of various sizes are mixed to form only When the conductive carbon layer formed of graphene and/or nanographene is used, the electric resistance of the conductive carbon layer can be further reduced.

The content of graphene and/or nanographene The weight ratio of the solid content of the electric carbon layer to the entire weight is preferably 0.5% by weight or more. This reason is as described above.

(silver coating)

As the silver coating agent for forming the silver coating layer 15, the silver particles of the electrically conductive material are dispersed in a resin or the like, and can be roughly classified into a high-temperature firing molding and a polymer molding. In the high-temperature firing, the silver particles are fused to each other by heating to about 500 to 900 ° C to form a continuous conductive film to obtain conductivity. On the other hand, the polymer type improves the film properties, the dispersibility of the silver particles, and the substrate. For the purpose of adhesion, the resin is contained, and the resin is cured by heating from room temperature to a temperature of about 200 ° C, whereby the metal particles are brought into contact with each other to form a conductive film, thereby exhibiting conductivity.

Solid electricity using a conductive polymer as a solid electrolyte In the case of the capacitor, it is preferred to use a polymer type silver coating agent which can form a silver coating layer at a temperature lower than the decomposition temperature of the conductive polymer.

More specifically, a silver coating agent can be used to oxidize silver nanoparticles. The particles, and the silver neodymium silicate of the organic silver compound are mixed in a mixed coating agent of a specified organic solvent.

Moreover, as an organic silver compound used in a silver coating agent, In addition to silver neodecanoate, a silver salt of a tertiary fatty acid such as pivalic acid, neoheptanoic acid or neodecanoic acid can also be used.

Because the silver oxide of the silver coating agent is fine particles of nanometer grade Therefore, the gap of the capacitor element described above is trapped in the unevenness of the surface, and the contact area with the solid electrolyte layer can be sufficiently ensured.

Then, the silver coating agent first has a temperature range of 150 to 160 ° C Sintering for 30 minutes allowed the coating to harden. Then, it is heat-treated at a temperature of 170 to 190 ° C for 30 minutes to volatilize residual organic components on the surface of the silver coating.

By this heat treatment, the silver particles become mutually fused The conductive path inside the silver coating is ensured to increase the electrical conductivity of the entire silver coating layer 15. Moreover, the silver coating layer 15 does not cause microcracks in the above temperature range. Therefore, there is no obstruction of the conductive path due to micro-cracks. Broken, at this point, the resistance of the silver coating 15 can also be lowered.

The silver coating layer 15 described above constitutes the cathode lead of the present invention Floor. Further, the method for forming the cathode extraction layer is not limited to the above-described method of forming a silver coating layer by a silver coating agent, and various methods such as a method of forming a cathode extraction layer by metal vapor deposition may be employed.

Next, the mounting substrate 2 will be described. Mounted substrate with epoxy glass The insulating substrate 21 such as a substrate is a base, and includes an anode electrode 22 and a cathode electrode 23 on the bottom surface, and an anode conductor 24 and a cathode conductor 25 which are respectively connected to the anode portion and the cathode portion of the capacitor element, and an anode conductor of the upper surface and the back surface. 24 is electrically connected to the anode electrode 22, the cathode conductor 25, and the cathode electrode 23, respectively.

Moreover, the structure of the electrode on the bottom surface of the substrate 2 can be mounted. The shape of the connected CPU or the like is formed into an arbitrary shape, but is the same as the shape of the anode portion and the cathode portion of the capacitor element, and is formed to surround the cathode electrode 23 with the anode electrode 22 as shown in FIG. 2(b). The shape of the surrounding electrodes is better.

An anode conductor 24 formed on the upper surface of the mounting substrate 2, The pole conductor 25 may have a shape that fits the anode portion 17 and the cathode portion 16 of the capacitor element 1, respectively. Fig. 2(a) is a perspective view of the mounting substrate 2 as seen from above. As in the configuration of the capacitor element 1 described above, the cathode portion 16 is formed in the concave portion, and the periphery of the concave portion is formed as the shape of the capacitor element 1 of the anode portion 17, and the anode conductor 24 of the substrate 2 is mounted in accordance with the shape. The cathode conductor 25 is surrounded.

The thicknesses of the anode electrode 22 and the cathode electrode 23 are all By setting the same thickness, the mounting surface of the anode electrode 22 and the cathode electrode 23 is a horizontal plane, and the solid electrolytic capacitor can be stably mounted when mounted on the mounting substrate.

And the anode electrode 22 and the cathode electrode 23 like this In order to approach each other, the current flowing through the anode electrode 22 and the cathode electrode 23 is reversed, so that the magnetic fields generated by the currents flowing through the respective electrodes cancel each other, and the ESL can be lowered. Further, in order to prevent short-circuiting caused by mounting the substrate with solder when the anode electrode 22 and the cathode electrode 23 are brought close to each other, it is preferable to form the solder resist layer 26 between the anode electrode 22 and the cathode electrode 23.

In this way, it becomes an insulating substrate on which the substrate is mounted. A thickness of about 200 μm is suitable for strength, but a thickness of about 80 μm can also be used. Further, the anode electrode, the cathode electrode, and the conductor formed on the insulating substrate may each have a small electric resistance and can be bonded to the solder, and a copper or gold-plated nickel conductor is preferably used. The thickness of the electrode and the conductor can be formed by a thickness of 30 to 100 μm on one side.

Conducting the conductors 24, 25 and the bottom on the substrate 2 In the method of the electrodes 22 and 23, the specific position of the mounting substrate 2 can be perforated by laser, and the inner surface of the hole can be plated by via plating to form conduction. The position and number of the via plating for the conduction can be arbitrarily designed in accordance with characteristics such as the current capacity required for the solid electrolytic capacitor.

Mounting the substrate in this way, from the anode of the capacitor element The distance between the anode electrode and the cathode electrode of the substrate and the cathode electrode at the current outlet can be set to only the thickness of the substrate to be mounted, and current can be obtained. The shortening of the flow path. In particular, the thickness of the mounting substrate is preferably about 200 μm, but it can be manufactured to a thickness of about 80 μm, and the thickness of the conductor and the electrode of the mounting substrate can be formed by a thickness of about 30 μm. When the capacitor element is mounted on the resin mold of the lead frame, the distance from the cathode portion of the capacitor element to the cathode electrode on which the substrate is mounted can be extremely shortened. Therefore, it is possible to reduce the ESL of the solid electrolytic capacitor, and it is possible to rapidly supply electric power to the CPU or the like in the transient response.

The capacitor element 1 as described above is mounted on a mounting substrate 2. The anode portion 17 and the cathode portion 16 of the capacitor element 1 are respectively connected to the anode conductor 24 and the cathode conductor 25 of the mounting substrate with a conductive adhesive or the like to form a solid electrolytic capacitor.

Moreover, the dielectric film layer and solid of the solid electrolytic capacitor The electrolyte layer and the cathode portion are protected by mounting the substrate, and not only the mechanical pressure at the time of manufacture, but also stress applied to the solid electrolytic capacitor at the time of mounting, the stress can be buffered to alleviate the stress applied to the inside of the capacitor element. .

And, if necessary, capacitor elements can also be used as mold trees The grease is molded into a mold.

As described above, the capacitor element is about 100 μm thick. In the mounting substrate, the electrode including both surfaces and the thickness of the conductor layer have a thickness of about 140 μm, so that a solid electrolytic capacitor having a thickness of at least 240 μm can be obtained.

Moreover, if the thickness is to be further thinned, it can be used as the above The substrate on which the substrate is mounted is produced by using a flexible film-like resin film as a base.

In the solid electrolytic capacitor of the above embodiment, the capacity is The interface between the dielectric oxide film layer and the solid electrolyte layer, and the distance from the interface to the cathode electrode of the external electrode is short, and the internal resistance of the solid electrolytic capacitor is extremely lowered. In the solid electrolytic capacitor having such a structure that the internal resistance is lowered, the effect of lowering the ESR of the solid electrolytic capacitor by the conductivity of the conductive carbon layer of the present invention is more remarkable.

Further, the shape of the solid electrolytic capacitor is not limited to the above shape. For example, it is also applicable to a case where a solid electrolyte layer made of a conductive polymer is formed on the anode body obtained by sintering the tantalum powder, and a conductive carbon layer is further formed on the solid electrolyte layer. Further, the present invention can also be applied to a case where a solid electrolyte layer and a conductive carbon layer are formed over an anode body made of an aluminum plate, and the anode volume layer is further formed into a plurality of sheets to form a solid electrolytic capacitor.

Example

Next, an embodiment of the present invention will be described.

As the anode body, an aluminum material having a size of 5 × 5 mm and a thickness of 500 μm was prepared, and then a concave portion having a size of 3 × 3 mm was formed at the center portion thereof. An etching treatment was applied to the inner surface of the concave portion, and an anodic oxidation treatment was further performed at a voltage of 3.6 V to form a dielectric oxide film layer.

Then, in the concave portion, poly-3,4-ethylenedioxythiophene (PEDOT: A dispersion of poly(3,4-ethylenedioxythiophene)), after drying, forms a solid electrolyte layer made of PEDOT.

Further, a conductive carbon layer is formed on the solid electrolyte layer.

Banihaito (trade name) of a capacitor current collector coating made by Nippon Graphite Co., Ltd. was used as a coating agent for forming a conductive carbon layer, and the "graphene" manufactured by Bridgestone KBG Co., Ltd. was weighed and adjusted. Paint material. Moreover, "graphene" manufactured by Bridgestone KBG Co., Ltd. has a laminate of 2 to 40 layers and a thickness of 40 to 100 nm, so it conforms to the nanographene described in the specification. Hereinafter, "graphene" described in the examples is a trade name, and actually represents nanographene.

Add "graphene" to 0.3, 1, 3, 10, 20 When the coating material was adjusted by weight %, the viscosity of the coating agent adjusted by adding 10% by weight was increased. Further, even if 20% by weight is to be added to adjust the coating agent, the viscosity of the coating agent is too high to mix the materials, and a uniform coating agent cannot be produced.

Banihaito is contained as a binder in a polyester resin in an amount of about 10% by weight. Therefore, it is estimated that Banihaito is used as a raw material to adjust the amount of the coating agent, and the amount of "graphene" added can be increased to a small amount to improve the viscosity.

Here, in order to compare the amount of "graphene" added In addition, butyl carbitol was used as a solvent, and a phenol resin was used as a binder to change the amount of "graphene" and other carbon materials, and various coating agents were tried. As a result, even a constituent material of the conductive carbon layer after the coating agent is dried The weight ratio is set to 54% by weight of "graphene", 1% by weight of Ketjen black, and 46% by weight of phenol resin. The amount of each material added is not too high, and the viscosity of the coating agent is not too high. The solid electrolyte layer applied to the solid electrolytic capacitor (each material was almost uniformly mixed, and the workability was good).

Therefore, it has been found that the amount of "graphene" added can be 50% by weight or more by changing the constituent material of the coating agent. Further, considering the ESR characteristics of the capacitor, the amount of "graphene" added is preferably less than 50% by weight.

Table 1 below shows the ratio (content) of "graphene" after the addition amount of "graphene" and the adjustment of the paint material by using Banihaito as a raw material. Moreover, Banihaito also contains a spherical Ketchen Black, and the existence ratio (content) is also shown in the table. The table is described as having a range in the presence ratio column because the raw material of Banihaito has a maximum value and a minimum value of the allowable range of the solid component contained in the coating agent, and the coating agent is in the range of the maximum value and the minimum value. After all the organic solvent components were dried, a conductive carbon layer formed only of a solid component was formed, and the ratio of existence was calculated.

The above conventional examples and the first to fourth embodiments are used. The type of the coating agent was applied to the solid electrolyte layer and dried at 160 ° C to form a conductive carbon layer.

Further forming silver on a conductive carbon layer by a known method coating.

The capacitor element formed by the above method is mounted The solid electrolytic capacitors of the conventional examples and the first to fourth embodiments were completed on the same mounting substrate as the capacitor element.

The solids of the above conventional examples and Examples 1 to 4 were measured. Capacitance and ESR of electrolytic capacitors. Thereafter, the solid electrolytic capacitor was left unloaded at an ambient temperature of 170 ° C for 100 hours, and the rate of change in capacitance and ESR after standing was measured.

The results are shown in Table 2 below.

It can be seen from the results shown in Table 2 that the capacitance is in the past. As well as Examples 1 to 4, the initial values and the rate of change after leaving at 170 ° C for 100 hours did not seem to differ much. However, the initial values of the first to fourth embodiments were 11.8 to 10.4 mΩ with respect to the conventional initial value of ESR of 13.9 mΩ, and it was found that the ESR can be greatly reduced by 2.1 to 3.5 mΩ. Further, each of the examples in which the content of Ketjen black was 10 to 16% by weight was compared with the conventional example, and the ESR was reduced. Further, it was also found that Example 4 having a large content of "graphene" has a further ESR reducing effect as compared with Ketjen black.

Calculate the addition of "graphene" from the data of the above embodiment The addition is related to the initial value of ESR and the simulation when adding trace amounts of graphene. When 0.1% by weight of "graphene" was added in the same manner as in the above examples, the initial ESR value was 13.3 mΩ (Reference Example 1), and when 0.2% by weight was added, it was 12.7 mΩ (Reference Example 2). The amount of addition of "graphene" in Reference Example 1 and Reference Example 2 is 0.3 to 0.8% by weight and 0.6 to 1.6% by weight in terms of the ratio of "graphene".

The results of this simulation are shown in Table 3 below.

The simulation results shown in Table 3 indicate that even "graphite The existence ratio of the olefin is 0.5% by weight, and the ESR reduction effect of the solid electrolytic capacitor can also be seen.

In addition, compare the ESR after placing at 170 ° C for 100 hours, In the conventional example, the value of ESR is increased by 25 times. On the other hand, Examples 2 to 4 are 13 to 4.3 times, and the rate of increase is low. From this point of view, it is also known that as the amount of "graphene" added increases, the heat resistance of the solid electrolytic capacitor increases.

1‧‧‧ capacitor components

2‧‧‧Connecting board

11‧‧‧Aluminum

12‧‧‧Dielectric oxide coating

13‧‧‧Solid electrolyte layer

14‧‧‧ Conductive carbon layer

15‧‧‧Silver coating

16‧‧‧ Cathode

17‧‧‧Anode

21‧‧‧Insert substrate

22‧‧‧Anode conductor

23‧‧‧Cathode conductor

24‧‧‧Anode conductor

25‧‧‧Cathode conductor

26‧‧‧ solder resist layer

C‧‧‧Solid electrolytic capacitor

Claims (3)

A solid electrolytic capacitor is a solid electrolytic capacitor in which a dielectric oxide film layer, a solid electrolyte layer, a conductive carbon layer and a cathode lead layer are sequentially formed on a surface of an anode body made of a metal material, wherein The conductive carbon layer contains graphene and/or nanographene. The solid electrolytic capacitor according to claim 1, wherein the content of the graphene and/or nanographene which constitutes the solid component of the conductive carbon layer is 0.5% by weight or more. The solid electrolytic capacitor according to claim 1 or 2, wherein the conductive carbon layer further contains carbon black in an amount of 5 to 20% by weight based on the weight of the solid component constituting the conductive carbon layer.