JP2006156904A - Valve action metal body and its production process, electrolytic capacitor and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve action metal body ensuring sufficient capacitance emergence rate and excellent withstand voltage when an electrolytic capacitor is constituted. <P>SOLUTION: A valve action metal layer is chemically converted with chemical conversion liquid containing a proton donor polymer compound, and a dielectric layer is formed on the surface of the valve action metal layer thus obtaining a valve action metal body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a valve action metal body and a manufacturing method thereof, and an electrolytic capacitor and a manufacturing method thereof.

  In recent years, digitization, downsizing, and speeding up of electronic devices have been increasingly accelerated. Under such circumstances, an electrolytic capacitor that is one of the electronic components suitable for high frequency applications frequently used in various electronic devices is required to have a larger capacity and a lower impedance during high frequency operation than ever before. At the same time, there is a strong desire for operational stability, reliability, and a longer life.

  An electrolytic capacitor is generally composed of a so-called valve action metal layer made of aluminum, tantalum or the like, a dielectric layer made of an oxide film formed by anodizing the surface, an electrolyte layer, graphite, silver, or the like. It has a structure in which conductor layers are sequentially stacked.

  Such electrolytic capacitors are roughly classified into two types, that is, a liquid electrolytic capacitor and a solid electrolytic capacitor, depending on the properties of the electrolyte material constituting the electrolyte layer. The former includes an electrolyte layer containing a liquid electrolyte (electrolytic solution) as an electrolyte material, and the latter includes an electrolyte layer containing a solid electrolyte (complex salt, conductive polymer, etc.) as an electrolyte material. It is. Comparing these from the viewpoints of various characteristics, the former is inherently likely to cause deterioration over time due to leakage or evaporation (dry up) of the electrolyte, whereas the latter has almost no such fear.

  Based on these advantages, research and development of solid electrolytic capacitors has been actively carried out recently. In particular, from the viewpoint of leakage current value, impedance characteristics, heat resistance, etc., the focus of development and practical application is manganese dioxide and complex salts. There is a rapid shift from those using a conjugated conductive polymer in which an electron donating or electron withdrawing substance (dopant) is doped into polypyrrole, polythiophene, polyaniline or the like.

  By the way, in the electrolytic capacitor having the general configuration described above, the valve metal layer is usually roughened and widened to increase the capacity, and the surface thereof has a fine uneven shape. Therefore, the dielectric layer formed on the valve action metal layer has a fine uneven shape as well.

Here, a dielectric material layer is a layer which consists of an oxide film formed by anodizing (chemical conversion) the surface of a valve action metal layer as mentioned above. The chemical conversion treatment, that is, the anodic oxidation of the valve metal layer is generally performed by using a solution of ammonium adipate or the like as a chemical conversion solution and immersing the valve metal in this chemical conversion solution and applying a predetermined voltage. (For example, refer to Patent Document 1). Thereby, the valve action metal body which consists of a valve action metal layer and a dielectric material layer is formed.
Japanese Patent Laid-Open No. 11-45828

  However, a conventional electrolytic capacitor including a valve action metal body in which a dielectric layer is formed using a chemical conversion liquid such as ammonium adipate described above can obtain a capacity close to the theoretical capacity, that is, a sufficient capacity appearance rate. The inventors have found that it is difficult to obtain.

  Furthermore, the electrolytic capacitor is also required to have excellent voltage resistance. In order to improve the voltage resistance, for example, it is effective to increase the thickness of the dielectric layer in the valve action metal body, but when the thickness of the dielectric layer is increased, the capacity tends to decrease, which is excellent. It is difficult to obtain voltage resistance and sufficient capacity at the same time. Then, when the thickness of the dielectric layer is set to such a thickness that the capacity required for the electrolytic capacitor is obtained, the valve action metal body in which the dielectric layer is formed using the above-described chemical conversion liquid such as ammonium adipate is used. The present inventors have found that it is difficult to obtain excellent voltage resistance with the conventional electrolytic capacitor provided.

  The present invention has been made in view of the above-described problems of the prior art, and a valve action metal body capable of obtaining a sufficient capacity appearance rate and excellent withstand voltage when an electrolytic capacitor is configured, and its An object of the present invention is to provide a manufacturing method, and an electrolytic capacitor and a manufacturing method thereof.

  In order to achieve the above object, the present invention can be obtained by forming a valve metal layer in a chemical conversion solution containing a proton donating polymer compound and forming a dielectric layer on the surface of the valve metal layer. The valve action metal body characterized by the above is provided.

  In such a valve metal body, the dielectric layer is formed by forming a valve metal layer using a chemical conversion liquid containing a proton donating polymer compound, and an electrolytic capacitor is formed using the valve metal body. When configured, a sufficient capacity appearance rate and excellent voltage resistance can be obtained.

  The present invention also re-forms a laminate having a valve action metal layer and a dielectric layer formed on at least a part of the valve action metal layer in a chemical conversion liquid containing a proton donating polymer compound. The valve action metal body is obtained by forming a dielectric layer on the surface of the valve action metal layer.

  In this way, a valve obtained by re-forming a laminated body in which a dielectric layer is previously formed on at least a part of the surface of the valve action metal layer using a chemical conversion liquid containing a proton donating polymer compound. According to the working metal body, when an electrolytic capacitor is configured, a sufficient capacity appearance rate and excellent voltage resistance can be obtained.

  In these valve action metal bodies, the proton donating polymer compound contained in the chemical conversion liquid when forming the dielectric layer is polyfluoroethylene having a perfluoroalkyl ether side chain containing a sulfonic acid group or a derivative thereof. It is preferable that

  Thus, the valve action metal obtained by performing formation of a valve action metal layer in a chemical conversion liquid containing polyfluoroethylene which has a perfluoroalkyl ether side chain containing a sulfonic acid group, or its derivative, or re-formation of a layered product According to the body, when an electrolytic capacitor is configured, it is possible to obtain a more sufficient capacity appearance rate and better voltage resistance.

  The present invention further includes a chemical conversion step in which the valve metal layer is formed in a chemical conversion liquid containing a proton donating polymer compound, and a dielectric layer is formed on the surface of the valve metal layer. A method for producing a metal body is provided.

  In addition, the present invention provides a laminate comprising a valve action metal layer and a dielectric layer formed on at least a part of the valve action metal layer in a chemical conversion liquid containing a proton donating polymer compound. And the manufacturing method of the valve action metal body characterized by having the chemical conversion process which forms a dielectric material layer on the said valve action metal layer surface.

  According to these manufacturing methods, it is possible to obtain a valve metal body capable of obtaining a sufficient capacity appearance rate and excellent voltage resistance when an electrolytic capacitor is configured.

  In these valve action metal body production methods, the proton-donating polymer compound contained in the chemical conversion liquid when forming the dielectric layer is polyfluoroethylene having a perfluoroalkyl ether side chain containing a sulfonic acid group. Or a derivative thereof.

  Depending on the case where the electrolytic capacitor is configured by forming the valve action metal layer or re-forming the laminate in the chemical solution containing polyfluoroethylene having a perfluoroalkyl ether side chain containing a sulfonic acid group or a derivative thereof. A valve action metal body capable of obtaining a sufficient capacity appearance rate and a superior voltage resistance can be obtained.

  The present invention also includes the above-described valve action metal body of the present invention, an electrode layer disposed to face the valve action metal body, and an electrolyte layer disposed between the valve action metal body and the electrode layer. And an electrolytic capacitor comprising:

  Since this electrolytic capacitor includes the valve action metal body of the present invention, a sufficient capacity appearance rate and excellent voltage resistance can be obtained.

  Here, the electrolyte layer is preferably a layer made of a solid electrolyte. That is, the electrolytic capacitor of the present invention is preferably a solid electrolytic capacitor having a solid electrolyte layer.

  When the electrolytic capacitor of the present invention is a solid electrolytic capacitor, it is possible to improve problems caused in the case of a liquid electrolytic capacitor, such as deterioration over time due to leakage or evaporation of the electrolytic solution. In a solid electrolytic capacitor, the conductive polymer compound is completely filled in the roughened / expanded portion of the valve action metal body in which the dielectric layer is formed on the surface of the valve action metal layer. However, since the capacity appearance rate is likely to be insufficient, it is possible to obtain a sufficient capacity appearance rate even with a solid electrolytic capacitor by providing the valve action metal body of the present invention, and Excellent voltage resistance can be obtained.

  The present invention further provides an electrolysis comprising a valve metal body, an electrode layer disposed opposite to the valve metal body, and an electrolyte layer disposed between the valve metal body and the electrode layer. There is provided a method for producing an electrolytic capacitor, the method comprising the step of forming a valve action metal body, wherein the valve action metal body is formed by the above-described method for producing a valve action metal body of the present invention. .

  According to this manufacturing method, since it has the valve action metal body formation process which forms a valve action metal body by the manufacturing method of the valve action metal body of the present invention, it has sufficient capacity appearance rate and excellent voltage resistance. It is possible to obtain an electrolytic capacitor capable of obtaining

  Here, the electrolyte layer is preferably a layer made of a solid electrolyte. That is, the electrolytic capacitor manufactured by the manufacturing method of the present invention is preferably a solid electrolytic capacitor including a solid electrolyte layer.

  As a result, it is possible to improve the problems that occur in the case of a liquid electrolytic capacitor, such as deterioration over time due to electrolyte leakage and evaporation, and it is possible to obtain a sufficient capacity appearance rate and excellent withstand voltage. A solid electrolytic capacitor can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, when an electrolytic capacitor is comprised, the valve action metal body which can obtain sufficient capacity | capacitance appearance rate and the outstanding voltage resistance, and its manufacturing method can be provided. In addition, according to the present invention, it is possible to provide an electrolytic capacitor having a sufficient capacity appearance rate and excellent voltage resistance and a method for manufacturing the same.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. The positional relationship such as up, down, left and right is based on the positional relationship in the drawing.

[Electrolytic capacitor]
First, the electrolytic capacitor of the present invention will be described. In the present embodiment, the case where the electrolytic capacitor is a solid electrolytic capacitor will be described. FIG. 1 is a schematic cross-sectional view showing an example of the solid electrolytic capacitor of the present invention. As shown in FIG. 1, the solid electrolytic capacitor 1 has a configuration in which a solid electrolytic capacitor element 18 to which an anode lead-out portion 8 and a cathode lead-out portion 10 are connected is covered with a resin mold layer 16. An external anode terminal 12 and an external cathode terminal 14 are connected to the anode lead-out portion 8 and the cathode lead-out portion 10, respectively. In the solid electrolytic capacitor element 18, the dielectric layer 4 is provided between the electrode (valve action metal layer) 2 and the electrode 6 that are alternately arranged at regular intervals. In addition, a valve action metal body 5 is constituted by the electrode 2 and the dielectric layer 4.

  FIG. 2 is a cross-sectional view schematically showing the main part of the solid electrolytic capacitor 1, and shows the state in which the electrode 2, the dielectric layer 4, the electrode 6 and the resin mold layer 16 are laminated in more detail. . In FIG. 2, the solid electrolytic capacitor 1 has a configuration in which an electrode 2, a dielectric layer 4, a solid electrolyte layer 20, and conductor layers 22 and 24 are sequentially laminated. Thus, the electrode 26 (second electrode layer) is composed of the conductor layers 22 and 24, and the electrode 6 is composed of the solid electrolyte layer 20 and the electrode 26.

(anode)
The electrode (valve action metal layer) 2 functions as an anode in the solid electrolytic capacitor 1. The surface is subjected to a roughening or widening process to form a fine concavo-convex shape, thereby increasing the surface area and increasing the capacity of the solid electrolytic capacitor 1. The material constituting the electrode 2 is not particularly limited as long as it is generally used for an electrolytic capacitor. A metal is mentioned. Among these, aluminum or tantalum is relatively preferably used. The thickness of the electrode 2 is usually preferably about 1 to 500 μm.

(Dielectric layer)
The dielectric layer 4 is formed so as to cover the surface of the electrode 2 along the irregular shape. The dielectric layer 4 is usually formed of a metal oxide film having electrical insulation (for example, an aluminum oxide film when the electrode 2 is aluminum), and is easily formed by oxidizing the surface layer portion of the electrode 2 by a predetermined method. Is done. The thickness of the dielectric layer 4 is usually 1 nm to 1 μm.

(Valve action metal body)
The valve metal body 5 of the present invention is composed of the electrode (valve metal layer) 2 and the dielectric layer 4. The valve action metal body 5 is obtained by forming the electrode 2 in a chemical conversion solution containing a proton donating polymer compound and forming the dielectric layer 4 on the surface of the electrode 2, or in advance on the surface. After the surface (cut surface) where the oxide film 4 is not formed is exposed by cutting the electrode 2 on which the dielectric layer 4 is formed, the oxide film 4 is re-formed on the cut surface in the chemical conversion liquid. This is obtained by forming the dielectric layer 4 on the surface of the electrode 2.

  Here, chemical conversion or re-chemical conversion is performed by anodizing the electrode 2 to form an oxide film and forming the dielectric layer 4. Specifically, the anodic oxidation at this time can be performed by immersing the electrode 2 in a chemical conversion solution and applying a constant voltage with the electrode 2 as a positive electrode. The applied voltage can be appropriately determined according to the thickness of the oxide film to be formed, and is usually set to a voltage of about several volts to several hundred volts.

  As the chemical conversion liquid, one containing a proton donating polymer compound is used. The proton donating polymer compound is a so-called proton conducting polymer compound capable of donating a proton (moving the proton freely). This proton-donating polymer compound is, for example, a compound in which a side chain containing a functional group capable of donating protons (hereinafter referred to as “proton-donating functional group”) is bonded to a polymer skeleton as a main chain. .

  Examples of the polymer skeleton as the main chain include polyfluoroethylene, polystyrene, poly (meth) acrylic acid (polyacrylic acid or polymethacrylic acid), polyimide, polyethylene, polypropylene, polybutadiene, and derivatives thereof.

  Examples of the proton-donating functional group include a sulfonic acid group, a phosphoric acid group, and a carboxyl group, and among these, a sulfonic acid group or a phosphoric acid group that is a relatively strong acid group is more preferable.

  As those having the above-described polymer skeleton and proton-donating functional group, polyfluoroethylene, polystyrene, poly (meth) acrylic acid, polyimide and derivatives thereof having sulfonic acid groups bonded thereto, and phosphoric acid groups are bonded. Poly (meth) acrylic acid and its derivatives are preferably used.

  As the proton-donating polymer compound, those having a perfluoroalkyl ether side chain containing a sulfonic acid group are more preferable, and polyfluoroethylene having a perfluoroalkyl ether side chain containing a sulfonic acid group and derivatives thereof are particularly preferable. preferable. This type of polyfluoroethylene is preferably a copolymer having fluoroethylene having a perfluoroalkyl ether side chain having a sulfonic acid group at the terminal and tetrafluoroethylene as a monomer unit, specifically, For example, the compound which has a repeating unit represented by following formula (1) is mentioned.

  In formula (1), p is approximately 3 to 20, preferably 5 to 15, q is approximately 1 to 1000, preferably 1 to 500, m is approximately 1 to 5, preferably 1 to 3, and n is approximately 1 to 1. 5, preferably an integer from 1 to 3.

  According to the valve metal body 5 obtained by performing the conversion of the electrode 2 or the re-formation of the laminated body in the chemical conversion liquid containing these proton donating polymer compounds, it is more sufficient when an electrolytic capacitor is configured. It is possible to obtain a capacity appearance rate and superior voltage resistance.

  In addition to the above-described proton-donating polymer compound, for example, those used in normal chemical conversion liquids such as ammonium borate, ammonium phosphate, and organic acid ammonium may be added to the chemical conversion liquid. Of these, the organic acid ammonium is preferably ammonium adipate.

  Further, the concentration of the proton donating polymer compound in the chemical conversion liquid is preferably 0.01 to 10% by mass, and more preferably 0.05 to 7% by mass. When the concentration is less than 0.01% by mass, a sufficient oxide film cannot be formed compared to the case where the concentration is within the above range, and the voltage resistance tends to be insufficiently improved. On the other hand, when the concentration exceeds 10% by mass, the proton-donating polymer compound is mixed with the dielectric layer 4 and the solid electrolyte layer 20 to be described later when an electrolytic capacitor is configured as compared with the case where the concentration is in the above range. Between them, the electron conductivity tends to decrease, and the improvement of the capacity appearance rate and the voltage resistance tends to be insufficient.

  When the valve action metal body 5 is obtained by re-forming the laminated body, the laminated body forms the electrode 2 and the dielectric layer 4 is formed on at least a part of the surface of the electrode 2. It can be prepared by forming. The chemical conversion here can be carried out, for example, by immersing the electrode 2 in a chemical conversion solution and applying a constant voltage with the electrode 2 as a positive electrode. The applied voltage can be appropriately determined according to the thickness of the oxide film to be formed, and is usually set to a voltage of about several volts to several hundred volts. The chemical conversion liquid used in the chemical conversion here is not particularly limited, and a known chemical conversion liquid may be used, or a chemical conversion liquid containing the proton donating polymer compound may be used. In addition, in order to save the labor required for such chemical conversion, a laminate that is commercially available with the dielectric layer 4 formed in advance on at least a part of the surface of the electrode 2 may be used.

  The laminated body prepared in this way may be cut into a size required for the valve action metal body 5 and used. In this case, by cutting the laminate, the surface (cut surface) of the electrode 2 where the dielectric layer 4 is not formed is exposed. However, by performing the above re-formation, the dielectric is applied to the cut surface. The layer 4 is formed separately, and the dielectric layer 4 is formed so as to cover the entire necessary portion of the electrode 2.

  In the valve action metal body 5 formed as described above, since the dielectric layer 4 is formed by chemical conversion or re-chemical conversion using a chemical conversion solution containing a proton donating polymer compound, the valve action metal body 5 is formed. The solid electrolytic capacitor 1 provided with can obtain a sufficient capacity appearance rate and excellent voltage resistance.

(cathode)
The solid electrolyte layer 20 is formed so as to fill the concave portion along the dielectric layer 4 on the fine irregular surface of the electrode 2 formed by the surface enlargement. The thickness of the solid electrolyte layer 20 is desirably a thickness that can cover the uneven surface, and is preferably about 1 to 100 μm. The solid electrolyte layer 20 contains at least a conductive polymer compound.

  Here, as the conductive polymer compound, those usually used can be used, for example, polyaniline, polypyrrole, polythiophene, polyfuran, and derivatives thereof can be used, and poly (3,4-ethylene Dioxythiophene) is particularly preferably used. These may be used alone or in combination of two or more.

  The solid electrolyte layer 20 preferably further contains a proton donating polymer compound. As this proton-donating polymer compound, the same compounds as described above can be used.

  These proton-donating polymer compounds have excellent ionic conductivity and function as oxidizing species in the solid electrolyte layer 20, or as a metal oxidation reaction catalyst by water or oxygen unavoidably present in the surroundings. It is considered to function. Therefore, when the oxide film constituting the dielectric layer 4 is damaged due to thermal shock or physical or chemical impact, the solid electrolyte layer 20 comes into contact with the anode at the damaged portion. The anode is oxidized by the oxidizing action or catalytic action of the proton donating polymer compound, and the oxide film can be regenerated. Thereby, the insulating property of the dielectric layer 4 is recovered and maintained. In other words, the solid electrolytic capacitor 1 can be provided with a self-healing function by containing the proton donating polymer compound in the solid electrolyte layer 20. As a result, the solid electrolytic capacitor can obtain better voltage resistance and a more sufficient capacity appearance rate.

  In addition, the content of the proton-donating polymer compound in the solid electrolyte layer 20 is preferably 0.01 to 50 parts by mass with respect to 100 parts by mass of the conductive polymer compound, and 0.1 to 45 parts by mass. More preferably, it is more preferably 0.2 to 40 parts by mass. When the content is less than 0.01 parts by mass, the self-repair function tends to be insufficient as compared with the case where the content is within the above range. On the other hand, when the content exceeds 50 parts by mass, various characteristics (capacity, leakage current value, impedance characteristics, heat resistance, etc.) as a solid electrolytic capacitor are reduced as compared with the case where the content is within the above range. Tend.

  In the solid electrolyte layer 20, in addition to the above proton-donating polymer compound, sulfonic acid compounds such as sulfosalicylic acid, phosphoric acid ester compounds such as urea phosphate and mono-n-butoxyethyl phosphate, maleic acid, Carboxylic acid compounds such as benzoic acid, p-nitrobenzoic acid, phthalic acid, and hydroxycarboxylic acid may be added. These additions tend to improve the self-repair function.

  The solid electrolyte layer 20 preferably further contains a water-soluble polymer compound together with the proton donating polymer compound. The water-soluble polymer compound retains water and can disperse the proton-donating polymer compound, and examples thereof include polyvinyl alcohol and cellulose.

  These water-soluble polymer compounds function as a medium for dispersing the proton-donating polymer compound, and greatly improve the dispersibility of the proton-donating polymer compound in the solid electrolyte layer 20 to provide excellent ion conduction. Sex can be obtained. Thereby, the outstanding self-repair function can be provided to a solid electrolytic capacitor.

  The content of the water-soluble polymer compound in the solid electrolyte layer 20 is preferably 0.01 to 50 parts by mass, and preferably 0.1 to 45 parts by mass with respect to 100 parts by mass of the conductive polymer compound. Is more preferable, and 0.2 to 40 parts by mass is particularly preferable. When the content of the water-soluble polymer compound is less than 0.01 part by mass, the self-repair function tends to be insufficient as compared with the case where the content is in the above range. On the other hand, when the content exceeds 50 parts by mass, various characteristics (capacity, leakage current value, impedance characteristics, heat resistance, etc.) as a solid electrolytic capacitor are reduced as compared with the case where the content is within the above range. Tend.

  The solid electrolyte layer 20 preferably further contains a dopant. The dopant is for increasing the conductivity of the conductive polymer compound. For example, the alkylbenzene sulfonic acid and its salt (for example, sodium paratoluene sulfonate), the alkyl naphthalene sulfonic acid and its salt (for example, isopropyl naphthalene). Sodium sulfonate) and phosphoric acid.

  By containing these dopants, the solid electrolyte layer 20 can obtain excellent electronic conductivity and a high capacity. Moreover, low ESR can be obtained.

  As a material of the conductor layers 22 and 24 constituting the electrode 26 formed on the solid electrolyte layer 20, for example, carbon or metal can be used. As the conductor layer 22, carbon, and as the conductor layer 24 are used. Silver can be used. The electrode 26 is not limited to the two-layer structure of the conductor layers 22 and 24, and may be composed of three or more layers.

  The anode lead-out part 8, the cathode lead-out part 10, the external anode terminal 12 and the external cathode terminal 14 are used for energizing the solid electrolytic capacitor element 18, and for example, all are iron (Fe) or copper (Cu ) And the like, and materials obtained by plating these conductive materials (for example, tin (Sn) plating or tin lead (SnPb) plating).

  The resin mold layer 16 constitutes the exterior of the solid electrolytic capacitor 1 and is made of, for example, an insulating resin material such as an epoxy resin.

  According to the solid electrolytic capacitor 1 described above, since the solid electrolyte is used as the electrolyte, it is possible to improve the problems caused in the case of the liquid electrolytic capacitor, such as deterioration with time due to leakage or evaporation of the electrolytic solution, and Since the valve action metal body 5 described above is provided, a sufficient capacity appearance rate and excellent voltage resistance can be obtained.

[Method of manufacturing electrolytic capacitor]
Next, the manufacturing method of the solid electrolytic capacitor of this invention for manufacturing the solid electrolytic capacitor 1 which has the above structures is demonstrated.

  FIG. 3 is a flowchart showing an example of a procedure for manufacturing the solid electrolytic capacitor 1 of the present invention. As shown in FIG. 3, first, the electrode (valve metal layer) 2 is formed by roughening or expanding the surface of the valve metal (electrode 2 member) by chemical or electrochemical etching ( Step S11: First electrode layer forming step).

  When forming the electrode 2, for example, as described above, an untreated valve metal that has not been roughened or enlarged is used, and the valve metal is roughened or roughened. A surface-treated valve metal that has been subjected to surface roughening or surface enlargement processing in advance may be applied separately, or may be roughened or subjected to surface expansion processing in order to save time and effort. May be used.

  Next, the surface of the electrode 2 (roughened or enlarged portion) is anodized (chemically formed) to form an oxide film, thereby forming the dielectric layer 4 (chemical conversion step). Thereby, the valve action metal body 5 which consists of the electrode 2 and the dielectric material layer 4 is formed (step S12; valve action metal body formation process).

  Here, the chemical conversion step is performed by forming the electrode 2 in a chemical conversion solution containing a proton donating polymer compound and forming the dielectric layer 4 on the surface of the electrode 2. More specifically, chemical conversion is performed by immersing the electrode 2 in the chemical conversion solution and applying a constant voltage with the electrode 2 as a positive electrode. The applied voltage can be appropriately determined according to the thickness of the oxide film to be formed, and is usually set to a voltage of about several volts to several hundred volts. Moreover, as a chemical conversion liquid, the thing similar to what was illustrated in description of an electrolytic capacitor can be used.

  Further, as described above, the chemical conversion step may be performed by using the electrode 2 on which the dielectric layer 4 is not formed and forming the electrode 2, or at least a part of the electrode 2 is previously subjected to dielectric. You may carry out by preparing the laminated body in which the body layer 4 was formed, and reforming the laminated body.

  When the chemical conversion step is performed by re-forming the laminate, the electrode 2 is first formed before the chemical conversion step, and the dielectric layer 4 is formed on at least a part of the surface of the electrode 2 to form the laminate. Prepare (preparation process). The formation of the electrode 2 in this preparation step can be performed, for example, by immersing the electrode 2 in a chemical conversion solution and applying a constant voltage using the electrode 2 as a positive electrode. The applied voltage can be appropriately determined according to the thickness of the oxide film to be formed, and is usually set to a voltage of about several volts to several hundred volts. The chemical conversion liquid used in the chemical conversion here is not particularly limited, and a known chemical conversion liquid may be used, or a chemical conversion liquid containing the proton donating polymer compound may be used. In addition, in order to save the labor required for such chemical conversion, a laminate that is commercially available with the dielectric layer 4 formed in advance on at least a part of the surface of the electrode 2 may be used.

  Thus, after preparing a laminated body, a chemical conversion process is performed by re-forming a laminated body. The re-formation here can be performed by a method similar to the method for forming the electrode 2 described above. In addition, you may cut | disconnect and use the laminated body to prepare for the magnitude | size requested | required as the valve action metal body 5. FIG. In this case, by cutting the laminate, the surface (cut surface) of the electrode 2 where the dielectric layer 4 is not formed is exposed. However, by performing the above re-formation, the dielectric is applied to the cut surface. The layer 4 is formed separately, and the dielectric layer 4 is formed so as to cover the entire necessary portion of the electrode 2.

  Moreover, after performing chemical conversion or re-chemical conversion, you may wash | clean the valve action metal body 5 as needed.

  By forming the valve action metal body 5 through the above chemical conversion step, the finally obtained solid electrolytic capacitor 1 can obtain a sufficient capacity appearance rate and excellent voltage resistance.

  In parallel with step S11 or S12, a polymerization solution containing the monomer constituting the conductive polymer compound described above and an oxidizing agent for oxidative polymerization of the monomer is prepared (step S13). The above-mentioned proton donating polymer compound, water-soluble polymer compound, dopant and the like can be added to this polymerization solution as necessary. As a solvent used when preparing this polymerization solution, polar solvents such as water and alcohol are used. As the alcohol, ethanol and butanol are preferable. These solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the monomer include aniline, pyrrole, thiophene, furan, and derivatives thereof. By polymerizing these, conductive polymers such as polyaniline, polypyrrole, polythiophene, polyfuran, and derivatives thereof. A compound can be obtained. In order to produce poly (3,4-ethylenedioxythiophene) as the conductive polymer compound, it is preferable to use 3,4-ethylenedioxythiophene as the monomer.

  Oxidizing agents used for the polymerization of monomers include halides such as iodine and bromine, metal halides such as silicon pentafluoride, protonic acids such as sulfuric acid, oxygen compounds such as sulfur trioxide, and sulfates such as cerium sulfate. Persulfates such as sodium persulfate, peroxides such as hydrogen peroxide, iron salts such as iron paratoluate, and the like. Moreover, you may use the oxidizing agent which also has a function as a dopant, and while using this oxidizing agent, you may use a dopant different from this further. Examples of the material having both functions of an oxidant and a dopant include iron salts as exemplified above as a dopant such as iron paratoluenesulfonate.

  Here, the solid content concentration in the polymerization solution is preferably 10 to 60% by mass. When the solid content concentration is less than 10% by mass, it is necessary to perform the polymerization treatment many times until a solid electrolyte layer having a desired thickness is formed, as compared with the case where the solid content concentration is within the above range. As the process time becomes longer, the improvement in high temperature reliability tends to be insufficient. On the other hand, when the solid content concentration exceeds 60% by mass, the monomer is introduced into the roughened or widened portion of the valve action metal body as compared with the case where the solid content concentration is within the above range. It is difficult, and the conductive polymer compound is insufficiently filled, so that the capacity of the solid electrolytic capacitor and the improvement of the high temperature reliability tend to be insufficient.

  When the polymerization solution contains a proton-donating polymer compound, the content is preferably 0.01 to 50 parts by mass, and 0.1 to 45 parts by mass with respect to 100 parts by mass of the monomer. Is more preferable, and it is still more preferable that it is 0.2-40 mass parts. When the content is less than 0.01 parts by mass, the self-repair function of the obtained solid electrolytic capacitor tends to be insufficient as compared with the case where the content is in the above range. On the other hand, when the content exceeds 50 parts by mass, various characteristics (capacity, leakage current value, impedance characteristics, heat resistance, etc.) of the obtained solid electrolytic capacitor are reduced as compared with the case where the content is within the above range. Tend to.

  When the polymerization solution contains a water-soluble polymer compound, the content is preferably 0.01 to 50 parts by mass, and 0.1 to 45 parts by mass with respect to 100 parts by mass of the monomer. Is more preferable, and 0.2 to 40 parts by mass is particularly preferable. When the content is less than 0.01 parts by mass, the self-repair function of the obtained solid electrolytic capacitor tends to be insufficient as compared with the case where the content is in the above range. On the other hand, when the content exceeds 50 parts by mass, various characteristics (capacity, leakage current value, impedance characteristics, heat resistance, etc.) of the obtained solid electrolytic capacitor are reduced as compared with the case where the content is within the above range. Tend to.

  Then, the polymerization solution is attached onto the dielectric layer 4 of the valve action metal body 5 by immersing the valve action metal body 5 in the polymerization solution or by applying the polymerization solution to the valve action metal body 5. (Step S14). Next, the monomer contained in the polymerization solution adhered on the dielectric layer 4 is chemically oxidatively polymerized with an oxidizing agent to form the solid electrolyte layer 20 on the dielectric layer 4 (step S15; polymerization process).

  In the polymerization step, the solid electrolyte 20 is formed using a polymerization solution containing a monomer and an oxidizing agent. However, the monomer and the oxidizing agent may be prepared as separate solutions. . In this case, the monomer and the oxidizing agent are brought into contact with each other by, for example, alternately immersing the valve action metal body 5 in each solution or by alternately applying each solution to the valve action metal body 5. Chemical oxidation polymerization of monomers can be performed.

  In the polymerization step, the polymerization of the monomer can be performed by leaving the valve action metal body 5 in a state where the monomer and the oxidant are adhered in the air, but the monomer polymerization reaction is promoted. Therefore, the valve metal body 5 to which the monomer and the oxidizing agent are attached may be left in a high temperature environment. The standing time is not particularly limited, and can be appropriately determined according to the composition of the polymerization solution to be used, the solid content concentration, or other conditions.

  Further, after the polymerization of the monomer, the valve action metal body 5 may be washed and dried. Here, the cleaning is performed by removing impurities of the polymerization composition by using water, alcohol, or the like as a cleaning liquid and spraying it onto the valve action metal body 5 or immersing the valve action metal body 5 in the cleaning liquid. Done. At this time, the cleaning liquid may be flowing or stirred. Further, drying is performed at a temperature at which a liquid such as a cleaning liquid attached to the valve action metal body 5 can be removed.

  In the present invention, the polymerization step may be performed at least once, but may be repeated a plurality of times. By repeating the polymerization step a plurality of times, the solid electrolyte layer 20 having a desired thickness can be formed.

  Next, a conductive member (second electrode layer member) is laminated on the solid electrolyte layer 20 to form the electrode 26 (step S16; second electrode layer forming step). Lamination is performed by, for example, applying a paste made of a conductive member on the solid electrolyte layer 20 to form the conductor layer 22, and further applying a paste made of a different conductive member thereon. This can be done by forming the conductor layer 24. Specifically, for example, after applying and drying a carbon paste on the solid electrolyte layer 20, the conductor layers 22 and 24 can be formed by applying and drying a silver paste.

  After forming the solid electrolytic capacitor element 18 in this way, the anode lead-out portion 8 and the cathode lead-out portion 10 are connected to the electrodes. Subsequently, after each lead-out portion is connected to the external anode terminal 12 and the external cathode terminal 14, the entire solid electrolytic capacitor element 18 is resin-molded so that a part of the external anode terminal 12 and the external cathode terminal 14 are exposed to the outside. The solid electrolytic capacitor 1 is obtained by covering with the layer 16 (step S17). Then, it is preferable to perform an aging process further (step S18; post-processing process). The aging treatment can be performed by applying a constant voltage to the external anode terminal 12 and the external cathode terminal 14 of the solid electrolytic capacitor 1, thereby completing the manufacture of the solid electrolytic capacitor 1.

  In the solid electrolytic capacitor 1 manufactured in this way, since the valve action metal body 5 is formed through the above-described chemical conversion step, a sufficient capacity appearance rate and excellent voltage resistance can be obtained.

  In the present embodiment, an example of the structure and manufacturing method of the chip-type solid electrolytic capacitor 1 having the layer structure shown in FIG. 1 has been described. However, the electrolytic capacitor of the present invention is not limited to this, 2 may have a single layer structure, or may be a wound electrolytic capacitor formed by winding such a layer structure.

  In the present embodiment, the case of a solid electrolytic capacitor in which the electrolyte layer is a layer made of a solid electrolyte has been described. However, the electrolytic capacitor of the present invention is not limited to a solid electrolytic capacitor, and the above-described valve metal As long as the body 5 is provided, a liquid electrolytic capacitor may be used. In this case, for example, an electrolyte layer in which ammonium borate is dissolved in ethylene glycol is used.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
A solid electrolytic capacitor was manufactured through the following procedure. That is, first, an aluminum foil (3.5 mm × 6.5 mm) that has been subjected to a surface enlargement treatment is prepared as an anode, and a portion (anode portion) that should become an anode and a portion that should form a cathode (cathode) on the surface of the aluminum foil. The insulator for partitioning these was formed in the position which should partition with the formation part.

  Next, this aluminum foil was converted into a polyfluoroethylene solution having a sulfonic acid group-containing perfluoroalkyl ether side chain (Nafion (registered trademark) solution SE20192 (trade name, manufactured by Du Pont)) as a chemical conversion solution. After being immersed in (registered trademark) diluted with ethanol so that the solid content concentration becomes 1% by mass), a voltage of 6 V is applied to the aluminum foil to advance the anodic oxidation reaction. A dielectric layer made of an aluminum oxide film was formed on the surface layer. Thereby, the valve action metal body by which a dielectric material layer was formed on aluminum foil was obtained.

  Subsequently, 3,4-ethylenedioxythiophene (trade name: BAYTRON (registered trademark) M, manufactured by Bayel) as a monomer constituting the conductive polymer compound, 0.9 g of iron paratoluenesulfonate ( Trade name: BAYTRON (registered trademark) C-B50, manufactured by Bayel) 10.81 g and butanol 2.63 g were mixed to prepare a polymerization solution. The valve action metal body was immersed in this solution for 1 minute and then pulled up and left in the air for 30 minutes with the polymerization solution attached. Thereby, the monomer in the polymerization solution adhering to the valve action metal body was oxidatively polymerized. The aluminum foil was then washed with running water for 15 minutes and dried at 100 ° C. for 5 minutes. The polymerization process from the immersion of the valve action metal body in the polymerization solution to the drying was repeated three times to form a solid electrolyte layer having a thickness of 1 μm on the dielectric layer.

  Next, a carbon paste layer as a conductor layer is applied to a thickness of 3 μm on the solid electrolyte layer, and a silver paste layer as a conductor layer is further applied to a thickness of 20 μm on the carbon paste layer. did. This formed the cathode which consists of a carbon paste layer and a silver paste layer. Thus, a capacitor element having a structure in which the anode, the dielectric layer, the solid electrolyte layer, and the cathode were laminated in this order was obtained.

  Thereafter, a conductive cathode lead was connected to the cathode side using a conductive adhesive, and a conductive anode lead was connected to the anode side with a resistance welding machine. And the solid electrolytic capacitor was produced by covering the circumference | surroundings of a capacitor | condenser element so that an anode lead and a cathode lead may be partially exposed with an epoxy resin, and forming a resin mold layer.

(Examples 2-3)
Examples 2 to 3 were the same as Example 1 except that the solid concentration of Nafion (registered trademark) in the chemical conversion liquid was 2.5% by mass in Example 2 and 7% by mass in Example 3. A solid electrolytic capacitor was prepared.

(Comparative Example 1)
In the same manner as in Example 1, except that an aqueous solution of ammonium adipate (concentration: 7% by mass) was used instead of the polyfluoroethylene solution having a perfluoroalkyl ether side chain containing a sulfonic acid group as a chemical conversion solution. The solid electrolytic capacitor of Example 1 was produced.

(Evaluation of capacity appearance rate)
For the cathode forming part (3.5 mm × 4.5 mm) of the aluminum foil that has been subjected to the surface enlargement treatment that constitutes the solid electrolytic capacitors of Examples 1 to 3 and Comparative Example 1, the theoretical capacity was previously set before forming the solid electrolyte layer. Have been measured. That is, each aluminum foil was immersed in an electrolytic solution (ammonium adipate aqueous solution), and a theoretical capacity was measured at a frequency of 120 Hz using an LCR meter 4284A manufactured by HEWLETT PACKARD.

On the other hand, about the solid electrolytic capacitor of Examples 1-3 and the comparative example 1, the electrostatic capacitance was measured by IMPANDANCE / GAIN-PHASE ANALYZER 4194A made from HEWLETT PACKARD, respectively. From the electrostatic capacity as the solid electrolytic capacitor and the theoretical capacity measured in advance, the capacity appearance rate (%) was obtained by the following formula.
Capacity appearance rate = (capacitance as solid electrolytic capacitor / theoretical capacity) × 100
The results are shown in Table 1.

(Evaluation of withstand voltage)
Ten solid electrolytic capacitors of Examples 1 to 3 and Comparative Example 1 were prepared, and a voltage was gradually applied to each of them at a rate of 0 to 100 mV / sec. The voltage (V) at the time when it started to flow was measured as the withstand voltage. The results are shown in Table 1. In addition, the value of withstand voltage in the table is an average value of 10 measured values.

  As is apparent from the results shown in Table 1, according to the solid electrolytic capacitors (Examples 1 to 3) of the present invention, compared with the solid electrolytic capacitor of Comparative Example 1, a sufficient capacity appearance rate and excellent resistance It was confirmed that the voltage was obtained.

It is a schematic cross section which shows one Embodiment of the solid electrolytic capacitor of this invention. It is sectional drawing which shows typically the principal part of the solid electrolytic capacitor 1 shown in FIG. It is a flowchart which shows an example of the procedure of the manufacturing method of the solid electrolytic capacitor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid electrolytic capacitor, 2 ... Electrode (1st electrode layer), 4 ... Dielectric layer (dielectric), 5 ... Valve action metal body, 6 ... Electrode, 8 ... Anode lead-out part, 10 ... Cathode lead-out part, DESCRIPTION OF SYMBOLS 12 ... External anode terminal, 14 ... External cathode terminal, 16 ... Resin mold layer, 18 ... Solid electrolytic capacitor element, 20 ... Solid electrolyte layer, 22, 24 ... Conductor layer, 26 ... Electrode (2nd electrode layer), 30 ... Damaged part, 32 ... Repair part.

Claims (10)

  A valve metal body obtained by forming a valve metal layer in a chemical conversion solution containing a proton donating polymer compound and forming a dielectric layer on the surface of the valve metal layer.   A laminate having a valve action metal layer and a dielectric layer formed on at least a part of the valve action metal layer is re-formed in a chemical conversion liquid containing a proton donating polymer compound, and the valve action metal A valve metal body obtained by forming a dielectric layer on a layer surface.   The valve action metal body according to claim 1 or 2, wherein the proton-donating polymer compound is polyfluoroethylene having a perfluoroalkyl ether side chain containing a sulfonic acid group or a derivative thereof.   A method for producing a valve action metal body, comprising: forming a valve action metal layer in a chemical conversion liquid containing a proton donating polymer compound, and forming a dielectric layer on the surface of the valve action metal layer. .   A laminate having a valve action metal layer and a dielectric layer formed on at least a part of the valve action metal layer is re-formed in a chemical conversion liquid containing a proton donating polymer compound, and the valve action metal The manufacturing method of the valve action metal body characterized by having the chemical conversion process which forms a dielectric material layer on the layer surface.   6. The method for producing a valve action metal body according to claim 4, wherein the proton donating polymer compound is polyfluoroethylene having a perfluoroalkyl ether side chain containing a sulfonic acid group or a derivative thereof. The valve metal body according to any one of claims 1 to 3,
An electrode layer disposed opposite the valve action metal body;
An electrolyte layer disposed between the valve metal body and the electrode layer;
An electrolytic capacitor comprising:   The electrolytic capacitor according to claim 7, wherein the electrolyte layer is a layer made of a solid electrolyte. A method for producing an electrolytic capacitor, comprising: a valve metal body, an electrode layer disposed opposite to the valve metal body, and an electrolyte layer disposed between the valve metal body and the electrode layer. There,
A method for producing an electrolytic capacitor, comprising: a valve action metal body forming step of forming the valve action metal body by the method according to any one of claims 4 to 6. The method for manufacturing an electrolytic capacitor according to claim 9, wherein the electrolyte layer is a layer made of a solid electrolyte.

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