JPH02178912A - Solid electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To promote low impedance advancement in a high frequency region by forming a conductive resist layer at the specified part of an anode foil which is made by providing a valve metallic foil with a dielectric film, and forming a conductive polymer layer by the aqueous solution of electric polymeric monomer that the part of an anode foil, which is divided and isolated by a conductive resist layer, is dissolved by a supporting electrolyte. CONSTITUTION:A conductive resist layer 13, which is insoluble in water and soluble in organic solvent, is applied on the anode drawing-out part of an anode foil 11 that a valve metallic film is roughened and a dielectric film is provide by anode oxidation. The conductive resist layer 13 is never dissolved during electrolytic polymerization because the polymerization liquid is aqueous solution, and it effects the role of a power supply electrode and forms a conductive polymer layer 17 without making an electric bridge in the dielectric film. Hereby, it becomes suitable for impedance advancement in a high frequency region, and is cheep in manufacturing and easy to make, and the volumetric efficiency of capacity becomes favorable.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solid electrolytic capacitor that is suitable for lowering impedance in a high frequency region and has good volumetric efficiency of capacitance, and a method for manufacturing the same.

2. Description of the Related Art In recent years, with the digitalization of electronic devices, there has been an increasing demand for electrolytic capacitors with low impedance in the high frequency range. Conventionally, plastic film capacitors, mica capacitors, multilayer ceramic capacitors, and the like have been used as capacitors for high frequency regions. Other types include aluminum dry electrolytic capacitors and aluminum or tantalum solid electrolytic capacitors. Unfortunately, in aluminum and tantalum solid electrolytic capacitors, the electrolyte is solidified to improve the characteristics of the aluminum dry electrolytic capacitor. To form this isoelectrolyte, the anode body is immersed in manganese nitrate solution.
It is thermally decomposed in a high-temperature furnace at around 350"C to form a manganese dioxide layer. In addition, in recent years, solid electrolysis using organic semiconductors such as γ, 7, 8, 8-tetracyanoquinodimethane salt as a solid electrolyte has been developed. A capacitor has been developed.Furthermore,
In order to increase the conductivity of a solid electrolyte, a method has been proposed in which polymerizable monomers such as pyrrole, thione-5-heene, and furan are electrolytically polymerized to form a conductive polymer, and this is used as a solid electrolyte. Regarding conductive polymers, it is possible to prototype capacitors using conductive polymers with conductivity of approximately 1 to 1005-cm, and they have good frequency characteristics in the high frequency range and a wide temperature range that takes advantage of the advantages of solids. It is expected that it will be possible to realize these characteristics. According to Japanese Unexamined Patent Publication No. 63-232413, an insulating layer for separating an anode and a cathode is provided on a roughened valve metal plate at a predetermined portion, and then a dielectric film layer, a conductive polymer layer, and a graphite layer are applied. layer and silver paint layer are formed sequentially. −
According to Japanese Unexamined Patent Publication No. 63-239917, masking is applied to the part that will become the anode from the insulating layer for separating the anode and cathode, and a dielectric film layer, a conductive polymer layer, and a graphite layer are formed. and a manufacturing method in which the masking is removed after sequentially forming silver paint layers. Further, as a laminating means, the capacitor elements obtained as described above were stacked so that the anodes and cathodes corresponded to each other (6/<-7), and the cathodes were bonded to each other by silver paint and the anodes by welding or the like. ing.

Problems to be Solved by the Invention However, the above conventional configuration has the following problems.

■ Since the valve metal plate was set in a predetermined shape before forming the dielectric film, it was difficult to obtain an effective dielectric film and short-circuits were likely to occur.

■ Masking was performed on the page after the insulating layer was provided, resulting in a redundant manufacturing method, and the provision of the insulating layer also resulted in a low volumetric efficiency of capacitance.

■ It is difficult to obtain high reliability if the anodes are joined to each other by welding or the like in a laminated method, and it is difficult to obtain high reliability if the anodes are joined together at once, and even if the anodes are joined together several times individually, it is difficult to achieve high reliability. The process was complicated.

■ When forming a conductive polymer layer by electrolytic polymerization, electrical bridges were created in the dielectric film because electricity was supplied directly from the valve metal plate, making it easy for products to short-circuit7.

The present invention solves the above-mentioned conventional problems, and includes a solid electrolytic capacitor that uses a conductive polymer, is suitable for reducing impedance in a high frequency range, is inexpensive and easy to manufacture, and has good volumetric capacity efficiency, and a method for manufacturing the same. The purpose is to provide the following.

Means for Solving the Problem In order to solve this problem, the solid electrolytic capacitor of the present invention and its manufacturing method utilize aluminum foil, tantalum foil,
A conductive resist layer is formed on a predetermined portion of the anode foil, which is made by roughening a valve metal foil such as niobium foil or titanium foil and further providing a dielectric film by anodizing, and the anode is isolated in sections by the conductive resist layer. The foil portion is composed of a conductive polymer layer formed from an aqueous solution of an electrolytically polymerizable monomer in which a supporting electrolyte is dissolved, and the valve metal foil is roughened and a dielectric film is further provided by anodizing. An anode foil in the form of a band with a plurality of protrusions formed on one side at predetermined intervals, or an anode foil in the form of a strip and connected to one side of a support plate made of valve metal at predetermined intervals by welding or the like. A step of providing a dielectric film on the cut portion using a chemical solution, and uniformly attaching a semiconductor made of an organic or inorganic compound in the form of an island or layer to the entire cathode extraction portion on the surface of the protrusion or strip-shaped anode foil portion. a step of forming a conductive resist layer on a predetermined portion of the protrusion or strip-shaped anode foil portion; and forming a conductive polymer layer on the surface of the cathode extraction portion sectioned and isolated by the conductive resist layer. a step of sequentially forming a graphite layer and a silver paint layer for exposing the cathode on the surface of the conductive polymer layer; a step of dissolving and removing the conductive resist layer with an organic solvent; a step of laminating the cathode extraction portion by bending the strip-shaped portion or the support plate; a step of forming a silver paint layer again on the silver paint layer; The method includes the steps of cutting the protrusion or strip-shaped anode foil portion leaving an anode extraction portion, and attaching terminals to the anode extraction portion and the cathode extraction portion, respectively.

Effect: With this configuration and method, a conductive resist layer that is insoluble in water and soluble in organic solvents is coated on the anode lead-out portion of the anode foil, which has been roughened on the valve metal foil and further provided with a dielectric film by anodizing. During electrolytic polymerization, since the polymerization solution is an aqueous solution, the conductive resist layer does not dissolve and acts as a power supply electrode, forming a conductive polymer layer without creating electrical bridges in the dielectric film. Furthermore, by removing the conductive resist layer soluble in the organic solvent with an organic solvent, the conductive polymer layer, which is the cathode lead electrode, can be separated from the anode lead part, and the product can be made difficult to show 1-L. can. Furthermore, since the conductive resist layer is soluble in an organic solvent, it can be easily removed during the manufacturing process. In addition, by bending the anode lead-out portion, the reliability of the product can be increased without affecting the reliability of welding, etc.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.
-Explain from beginning to end.

Figures 2 and 3 show the structure of a capacitor element foil constituting a solid electrolytic capacitor in an embodiment of the present invention. Figure 2 shows a strip-shaped capacitor element foil with a plurality of protrusions formed at predetermined intervals on one side. FIG. 3 shows a capacitor element foil in which an anode foil is formed into a strip and connected to one side of a support plate made of valve metal at predetermined intervals by welding or the like. In FIG. 1, 11 is an anode foil made of roughened aluminum foil and further provided with a dielectric film, 12 is a protrusion covered with a semiconductor layer,
13 is a conductive resist layer. In Figure 3, 14
12 is a strip-shaped aluminum anode foil covered with a semiconductor layer; 13 is a conductive resist layer; 15 is an aluminum support plate;
indicates the weld between the anode foil and the support plate.

The valve metal foil serving as the capacitor element may be made of aluminum, tantalum, titanium, niobium, etc., and aluminum is used in this embodiment. The shape of the capacitor element foil may be such that the portion where the conductive polymer layer is formed does not damage the dielectric film at the portion where the conductive polymer layer comes into contact in a step before forming the conductive polymer layer. In this embodiment, the shape shown in FIG. 2 is used.

FIG. 4 is an enlarged view of the protrusion 12 in FIG. 2 in which a graphite layer and a silver paint layer are sequentially formed on the conductive polymer layer for cathode extraction, and FIG. 4(a) is a plan view thereof. 4(b) shows a sectional view taken along the line AA of FIG. 4(a). In FIG. 4, 11 is an anode foil made of roughened aluminum foil and further provided with a dielectric film, 16 is a semiconductor layer, 13 is a conductive resist layer, 17 is a conductive polymer layer, 1
8 represents a graphite layer, and 19 represents a silver paint layer.

A method of manufacturing the solid electrolytic capacitor element configured as described above will be described below.

First, aluminum etched chemically formed foil is punched out with a die into the shape shown in FIG. 2, and the dielectric film damaged by the punching is repaired by a known chemical conversion treatment method. Next, manganese nitrate is attached to the surface of the projection 120 and thermally decomposed to produce manganese dioxide. In addition,
In this example, thermal decomposition of manganese nitrate was used as a means to uniformly adhere semiconductors made of organic or inorganic compounds in the form of islands or layers. It is also possible to use semiconductor materials such as oleic acid, which is difficult to achieve. In short, it is sufficient that the semiconductor material is thinly and uniformly adhered to the surface of the dielectric film.

Next, the conductive resist layer 13 is formed so that each protrusion 12 is isolated. In this example, a carbon conductive paint was used as the conductive substance that is insoluble in water and soluble in an organic solvent, but the present invention is not limited to this, and for example, a conductive paint made of silver thread may be used. ．． It may be a charge transfer complex having γ, 8,8-tetracyanoquinodimethane or the like as an acceptor, or an organic semiconductor such as a solvent-soluble conductive polymer. In short, any electrically conductive power supply material that is insoluble in water and soluble in organic solvents may be used.

Next, each protrusion 12 is immersed in an aqueous solution of an electrolytically polymerizable monomer in which a supporting electrolyte is dissolved, the conductive resist layer 13 is used as a positive electrode as a power supply electrode, and an aqueous solution of an electrolytically polymerizable monomer in which -7 is dissolved is immersed in the supporting electrolyte 13. A predetermined DC voltage is supplied as a negative electrode. Conductive polymer layer 17 in FIG.
is formed on the anode foil 11 via the semiconductor layer 16. In this example, the sodium salt of triisopropylnaphthalene sulfonate was used as the supporting electrolyte, and virol was used as the electrolytically polymerizable monomer, but the invention is not limited thereto.
It is also possible to use the sodium salt of 1. using thiophene as an electrolytically polymerizable monomer. The point is that the conductive polymer layer can be electrochemically formed using an aqueous solution for electrolytic polymerization.

To form the graphite layer 18 and the silver paint layer 19 on the conductive polymer layer 1a, the portion of the anode foil 11 on which the conductive polymer layer 17 is formed is immersed in a graphite solution, and then cured. After forming the graphite layer 18, it is further immersed in a silver paint solution and then hardened to form a silver paint layer 19.

Next, remove the conductive resist layer by dissolving it with an organic solvent.
＼-Noru. In this example, the carbon conductive paint that is the semiconductor layer 16 was removed using dimethylformamide, but the organic solvent is not limited to this. Ultrasonic cleaning may also be used when removing the scum. Note that in this step, the anode foil 11 is folded 9 times.
Needless to say, this may be carried out after bending.

Next, the sheets are alternately bent along the line B-B in FIG. 4 (?L), and a predetermined number of sheets are stacked so that the protrusions 12 overlap each other. FIG. 5 is a side view showing a state in which four conductive resist layers are laminated. In Fig. 5, 11 is an anode foil made of roughened aluminum foil and further provided with a dielectric film;
19 indicates a conductive resist layer, and 19 indicates a silver paint layer. After the conductive resist layer 13 is dissolved and removed using an organic solvent, the silver paint layer 19 is immersed in a silver paint solution and then cured. Next, the anode foil 11 is cut along the line CC in FIG. 5, leaving only the part necessary for drawing out the anode.

FIG. 1 shows the configuration of a solid electrolytic capacitor in one embodiment of the present invention, and FIG. 1(a) is a top view thereof, and FIG.
Figure ('b) shows its plan view. 15 in Figure 1,
-2, 11 is an anode foil made of roughened aluminum foil and further provided with a dielectric film, 19 is a silver paint layer, 20 is an anode lead, 2
1 is a cathode lead, and 22 is an exterior.

FIG. 6 shows the impedance frequency characteristics of the solid electrolytic capacitor constructed as described below. Figure 6 shows a rated capacity of 16V and a rated capacity of 1oμF, dimensions of 6.5cm x 6.
Orran X 4. This shows the impedance up to about 10 Mflz for one embodiment of the present invention of Omm, and it can be seen that the impedance is almost close to ideal characteristics up to IMllz or higher.

Effects of the Invention As described above, the present invention provides an excellent solid electrolytic capacitor that uses a conductive polymer, is suitable for lowering impedance in a high frequency range, is inexpensive, easy to manufacture, and has high capacity and volume efficiency, and a method for manufacturing the same. It is possible to realize this.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a solid electrolytic capacitor in an embodiment of the present invention, FIG. 1(a) is its top view, FIG. 1('b) is its top view, and FIG. 2 is the present invention. 3 is a front view of a strip-shaped capacitor element foil having a plurality of protrusions formed at predetermined intervals on one side of a solid electrolytic capacitor in one embodiment; FIG.
The figure is a front view of a capacitor element foil in which strips of anode foil are connected by welding at predetermined intervals to one side of a support plate made of valve metal. This is an enlarged view of the state in which a graphite layer and a silver paint layer are sequentially formed on the conductive polymer layer.
is its plan view, and Fig. 4 ('b) is Fig. 3 (a) (7).
FIG. 5 is a side view showing a state in which four conductive resist layers are laminated, and FIG. 6 is an impedance frequency characteristic diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 11--Anode foil made by roughening aluminum foil and further providing a dielectric film, 12--Protrusion covered with semiconductor layer, 13--Conductive resist layer, 14 A: Aluminum support plate, 15--Welded part of anode foil and support plate, 16--Semiconductor layer, 17--Conductive polymer layer, 18--Graphai l-layer, 19...
...Silver pane l-layer, 2o...Anode lead, 21
...Cathode lead, 1/22... Exterior. Name of agent: Patent attorney Shigetaka Awano (1 person)
) ward

Claims (6)

[Claims] (1) A conductive resist layer is formed on a predetermined portion of the anode foil, which is made by roughening the valve metal foil and is further provided with a dielectric film by anodizing, and the portions of the anode foil that are sectioned and isolated by the conductive resist layer are A solid electrolytic capacitor with a conductive polymer layer formed from an aqueous solution of electrolytically polymerizable monomers in which a supporting electrolyte is dissolved. (2) Conductive paint containing carbon or silver that is insoluble in water and soluble in organic solvents as a conductive resist layer, 7, 7, 8,
2. The solid electrolytic capacitor according to claim 1, wherein a charge transfer complex having 8-tetracyanoquinodimethane or the like as an acceptor or a solvent-soluble conductive polymer is used. (3) As a supporting electrolyte in which the conductive polymer layer is composed of one or two of the sodium salts of polyvinyl sulfonate, dodecylbenzene sulfonate, triisopropylnaphthalene sulfate, isopropyl phosphate, or n-butyl phosphate. The solid electrolytic capacitor according to claim 1, which is a polymerized solid electrolytic capacitor. (4) The solid electrolytic capacitor according to claim 1, wherein the conductive polymer layer is polymerized using pyrrole, thiophene, or furan as a monomer. (5) The solid electrolytic capacitor according to claim 1, wherein aluminum foil, tantalum foil, niobium foil or titanium foil is used as the valve metal foil. (6) A valve metal foil with a roughened surface and a dielectric film formed by anodizing the anode foil, which is shaped like a belt and has a plurality of protrusions formed at a predetermined interval on one side, or the anode foil is shaped into a strip to form a valve. A step of applying a dielectric film to the cut portion of a support plate made of metal, connected by welding or the like at a predetermined interval using a chemical solution, and taking out the cathode on the surface of the protrusion or strip-shaped anode foil portion. A step of uniformly attaching a semiconductor made of an organic or inorganic compound to the entire part in the form of islands or layers;
a step of forming a conductive resist layer on a predetermined portion of the protrusion or the strip-shaped anode foil portion; a step of forming a conductive polymer layer on the surface of the cathode extraction portion sectioned and isolated by the conductive resist layer; a step of sequentially forming a graphite layer and a silver paint layer for taking out the cathode on the surface of the conductive polymer layer; a step of dissolving and removing the conductive resist layer with an organic solvent; a step of bending the support plate to laminate the cathode extraction portion; a step of forming a silver paint layer again on the silver paint layer; and a step of forming the protrusion or strip-shaped anode on which the conductive polymer layer is not formed. A method for manufacturing a solid electrolytic capacitor, which includes at least the steps of: cutting a foil portion leaving an anode extraction portion; and attaching terminals to the anode extraction portion and the cathode extraction portion, respectively.