JP2009231645A - Solid electrolytic capacitor, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor using a conductive polymer cathode layer improved in heat resistance; and a manufacturing method thereof. <P>SOLUTION: This solid electrolytic capacitor is provided with a capacitor element 1 in which an anode foil with a dielectric coating formed thereon and a cathode foil facing it are wound by interposing separator paper between them, and a conductive polymer cathode layer containing a fullerene compound (a fullerene compound bonded to a polymer skeleton of a conductive polymer cathode layer and a fullerene compound dispersed in the conductive polymer cathode layer) having a C60 structure is formed in its inside. Such a conductive polymer cathode layer is formed by preparing a chemical polymerization liquid formed by mixing a monomer solution of 3, 4-ethylenedioxythiophene with a solution with a ferric salt of sulfonated fullerene C60 as a dopant and oxidizer dissolved in a butyl alcohol solvent, immersing the capacitor element 1 in the chemical polymerization liquid, and thereafter including the sulfonated fullerene C60 as a fullerene compound by oxidation polymerization. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor and a manufacturing method thereof, and more particularly to a solid electrolytic capacitor having a conductive polymer cathode layer and a manufacturing method thereof.

  In recent years, with the downsizing and high performance of electronic devices, there has been a demand for a solid electrolytic capacitor having a large capacitance per product volume and a low equivalent series resistance (ESR). In view of the above, a solid electrolytic capacitor using an organic semiconductor such as a TCNQ complex salt or a conductive polymer such as polypyrrole, polythiophene, polyfuran, or polyaniline as a solid electrolyte has attracted attention. These conductive polymers have a higher electrical conductivity than manganese dioxide, which is a solid electrolyte that has been used in conventional solid electrolytic capacitors, and thus can greatly contribute to lowering the ESR of solid electrolytic capacitors. .

As the conductive polymer, those obtained by chemical oxidative polymerization or electrolytic oxidative polymerization of monomers (pyrrole, thiophene, furan, aniline, etc.) that are the basic skeleton are generally employed. In addition, an organic sulfonic acid is mainly used as a dopant agent when performing such oxidative polymerization, and among them, an aromatic sulfonic acid (for example, an alkylbenzene sulfonic acid or an alkylnaphthalene sulfonic acid) is particularly used to improve heat resistance. Is adopted. Moreover, the metal which has an oxidizing action is used for the oxidizing agent at the time of performing oxidative polymerization, and ferric iron is frequently used among them. For these reasons, ferric salts of aromatic sulfonic acids are usually used as dopants and oxidants in oxidative polymerization (see, for example, Patent Document 1 and Patent Document 2).
JP 10-32145 A JP-A-11-31626

  In the above conventional solid electrolytic capacitors, aromatic sulfonic acid is added to improve the heat resistance of the conductive polymer. However, due to the recent high-temperature treatment such as lead-free solder reflow and the increase in the guaranteed temperature, the conductivity can be increased. There is a demand for higher heat resistance of functional polymers.

  The present invention has been made in view of these problems, and an object thereof is to provide a solid electrolytic capacitor using a conductive polymer cathode layer with improved heat resistance and a method for producing the same.

  In order to achieve the above object, a solid electrolytic capacitor according to the present invention is a solid electrolytic capacitor in which a dielectric layer and a conductive polymer cathode layer are sequentially formed on the surface of an anode body. And a fullerene compound bonded to a polymer skeleton of the conductive polymer cathode layer and a fullerene compound dispersed in the conductive polymer cathode layer. Here, the fullerene compound bonded to the polymer skeleton of the conductive polymer cathode layer means a fullerene compound in a state of functioning as a dopant of the conductive polymer cathode layer, and the fullerene dispersed in the conductive polymer cathode layer. The compound means a fullerene compound that is not bonded to the polymer skeleton of the conductive polymer cathode layer (a fullerene compound that does not function as a dopant for the conductive polymer cathode layer).

In order to achieve the above object, a method for manufacturing a solid electrolytic capacitor according to the present invention includes a method for manufacturing a solid electrolytic capacitor in which a dielectric layer and a conductive polymer cathode layer are sequentially formed on the surface of an anode body. As a dopant and oxidant for forming the molecular cathode layer by oxidative polymerization, a compound of a fullerene compound and a metal having an oxidizing action is dissolved in a solvent to be used as a conductive polymer cathode layer. It is characterized by containing a fullerene compound bonded to the polymer skeleton of the cathode layer and a fullerene compound dispersed in the conductive polymer cathode layer.

  According to the present invention, a solid electrolytic capacitor using a conductive polymer cathode layer with improved heat resistance and a method for producing the same are provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(First embodiment)
FIG. 1 is a schematic cross-sectional view showing the configuration of the solid electrolytic capacitor according to the first embodiment of the present invention, and FIG. 2 is an exploded perspective view of the capacitor element constituting the solid electrolytic capacitor of FIG.

  In the solid electrolytic capacitor of the first embodiment, as the capacitor element 1, as shown in FIG. 2, an anode foil 2 having a dielectric film (not shown) formed as a dielectric layer and a cathode foil 3 opposite to the anode foil 2 are provided. What was wound through separator paper 4 is adopted. An anode lead wire 7 is drawn out from the anode foil 2 via a lead tab terminal 6, and a cathode lead wire 8 is drawn out from the cathode foil 3 via another lead tab terminal 6. As shown in FIG. 1, the fullerene compound (fullerene compound bonded to the polymer skeleton of the conductive polymer cathode layer and fullerene compound dispersed in the conductive polymer cathode layer) is contained inside the capacitor element 1. A conductive polymer cathode layer (not shown) is formed, the capacitor element 1 is housed in a bottomed cylindrical metal case 9, and a sealing rubber 10 is attached to the open end of the case 9. To do. The sealing rubber 10 is fixed by subjecting the opening end of the case 9 to lateral drawing and curling. Thereafter, a plastic seat plate 11 is inserted into the curled surface of the capacitor, and the lead wire (the anode lead wire 7 and the cathode lead wire 8) of the capacitor element is pressed and bent as the electrode terminal 12, and the chip type and the surface mounting are performed. An (SMD) type solid electrolytic capacitor is completed.

  The specific configuration of the solid electrolytic capacitor is as follows.

  The anode foil 2 is made of a foil made of metal having a valve action such as aluminum, tantalum, niobium, etc., and etching treatment for roughening the foil surface and formation of a dielectric film (dielectric layer) on the foil surface A chemical conversion treatment has been applied. An anode lead wire 7 is connected to the upper edge of the anode foil 2 via a metal lead tab terminal 6.

  As the cathode foil 3, a foil made of a metal having the same valve action as the anode foil 2 is employed. A cathode lead wire 8 is connected to the upper edge of the cathode foil 3 via a metal lead tab terminal 6. The cathode foil 3 may be a foil made of a valve metal different from the anode foil 2.

  The capacitor element 1 is configured by winding an anode foil 2 and a cathode foil 3 opposite to the anode foil 2 in a cylindrical shape through a separator paper 4 made of an insulator or the like, and then winding it with a winding tape 5 on the outer periphery. .

As the solid electrolyte, a conductive polymer such as polypyrrole, polythiophene, polyfuran, and polyaniline is employed. However, it is desirable to employ a conductive polymer composed of polythiophene or a derivative thereof as a solid electrolyte having good conductivity. . A conductive polymer as a solid electrolyte selected from the above is formed inside the capacitor element 1 by a known method such as impregnation or coating. In the embodiment of the present invention, fullerene (a compound in which carbon atoms form a spherical network structure) is included. Note that fullerene has a very large molecular weight and is therefore one of the characteristics of high heat resistance. For example, a C60 structure (60 carbon atoms having 12 five-membered rings and 20 six-membered rings). The fullerene (fullerene C60) having a structure formed of a soccer ball-like hollow molecule exhibits excellent stability even at a high temperature of 400 ° C. or higher.

  The metal case 9 is usually an aluminum case formed in a bottomed cylindrical shape with an aluminum plate or the like that is easy to form. The capacitor element 1 is housed and fixed in the case 9, and a sealing rubber 10 is attached to the opening end of the case 9 and sealed. In addition, as the metal case 9, a case made of metal such as stainless steel, copper, iron, brass or the like other than aluminum may be adopted, or a case made of these alloys may be adopted.

  The rubber 10 for sealing is an elastic body, in particular, silicon rubber (SR), fluorine rubber (FR), ethylene propylene rubber (EPT), high pylon rubber (CSM), which are materials having relatively high heat resistance and sealing properties. ), Butyl rubber (IIR), and isoprene rubber (IR). The sealing rubber 10 is formed with through holes for drawing out the lead tab terminals 6 connected to the anode lead wire 7 and the cathode lead wire 8, respectively. The sealing rubber 10 is attached to the opening end of the case 9 with the lead tab terminal 6 inserted into the through hole, and subjected to lateral drawing and curling on the opening end of the case 9. It is fixed.

  The plastic seat plate 11 has a through hole for allowing the anode lead wire 7 and the cathode lead wire 8 to pass therethrough, and is attached and fixed to the curled surface of the capacitor with both lead wires inserted. The anode lead wire 7 and the cathode lead wire 8 are bent along the plate surface of the seat plate 11 in the opposite directions as the electrode terminals 12.

(Production method)
Next, a method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present invention will be described.

  Step 1: A foil made of a valve metal (aluminum, tantalum, niobium, etc.) subjected to an etching process for roughening and a chemical conversion process for forming a dielectric film (dielectric layer) is used as an anode foil 2, Capacitor element 1 is formed by winding cathode foil 3 facing anode foil 2 in a cylindrical shape with separator paper 4 interposed therebetween. Anode lead wire 7 and cathode lead wire 8 are attached to anode foil 2 and cathode foil 3 via lead tab terminals 6, respectively. The capacitor element 1 is formed with a dielectric film on the end face of the anode foil 2 and subjected to cut formation and heat treatment in order to repair damaged portions and scratches caused by winding of the anode foil 2. The dielectric film is reinforced.

  Step 2: A chemical polymerization liquid in which a monomer (monomer) solution to be a conductive polymer and a solution in which a compound of a fullerene compound and an oxidizing metal as a dopant / oxidant is dissolved in an alcohol solvent are mixed. Prepare. Thereafter, the capacitor element 1 is immersed in the chemical polymerization solution, and a conductive polymer cathode layer is formed as a solid electrolyte inside the capacitor element 1 by oxidative polymerization. At this time, the reaction is facilitated by heat treatment to raise the temperature. The fullerene of the fullerene compound includes fullerene Cn represented by fullerene C60 (n = 60, 70, 76, 78, 82, 84, 86, 88, 92, 94, 96, 110) or a derivative thereof. Derivatives of the mixture are used. In addition, the alcohol solvent is used as a simple substance or a mixture of alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, and the metal constituting the metal salt having an oxidizing action is, for example, a transition metal. Iron (III), copper (II), chromium (VI), manganese (VII), and zinc (II) are used.

  Process 3: The rubber | gum 10 for sealing in which the predetermined through-hole was formed is prepared. Then, the lead tab terminal 6 of the capacitor element 1 is inserted into the through hole of the sealing rubber 10.

  Step 4: An aluminum case 9 formed in a bottomed cylindrical shape is prepared. The capacitor element 1 is housed and fixed inside the case 9.

  Process 5: The rubber 10 for sealing is arrange | positioned at the opening edge part of case 9, and a horizontal drawing process and a curl process are performed with respect to the opening edge part of case 9. In this way, the sealing rubber 10 is fixed, and the capacitor element 1 is sealed in the case 9 by the sealing rubber 10.

  Step 6: An aging process is performed in which a predetermined voltage is applied via both lead wires (the anode lead wire 7 and the cathode lead wire 8). Thereby, the characteristics of the capacitor element 1 are stabilized.

  Step 7: Finally, a plastic seat 11 is inserted into the curled surface of the capacitor, and both lead wires (the anode lead wire 7 and the cathode lead wire 8) of the capacitor element 1 are pressed and bent using the electrode terminals 12. .

  Through the above steps, the solid electrolytic capacitor in the first embodiment includes a fullerene compound bonded to the polymer skeleton of the conductive polymer cathode layer and a fullerene compound dispersed in the conductive polymer cathode layer. A solid electrolytic capacitor having a polymer cathode layer is manufactured.

  In the following examples, a solid electrolytic capacitor corresponding to the above-described first embodiment was produced, and the characteristics were evaluated. Moreover, in the comparative example, the solid electrolytic capacitor provided with the electroconductive polymer cathode layer formed using the conventional dopant and oxidizing agent was produced, and the characteristic evaluation was performed. Each of the solid electrolytic capacitors has a rated voltage of 4 V and a capacitance of 560 μF, and the outer dimensions are a diameter of 6.3 mm and a height of 12.0 mm.

(Example)
In Examples, a solid electrolytic capacitor A including a conductive polymer cathode layer containing sulfonated fullerene C60 as a fullerene compound was produced through the above-described steps (Step 1 to Step 7).

  Step 1A: Aluminum foil subjected to an etching treatment for roughening and a chemical conversion treatment (applied voltage 8 V, current density 4 mA / piece, applied time 2 to 5 hours) for forming a dielectric film (dielectric layer) Is used as the anode foil 2, and the cathode foil 3 facing the anode foil 2 is wound into a cylindrical shape via the separator paper 4 to form the capacitor element 1. The current density is managed by the current value per capacitor, and is changed according to the size of the capacitor. Anode lead wire 7 and cathode lead wire 8 are attached to anode foil 2 and cathode foil 3 via lead tab terminals 6, respectively. Thereafter, the capacitor element 1 is subjected to a cut formation process and a heat treatment at 260 ° C.

Step 2A: 3,4-ethylenedioxythiophene monomer solution and 40% by weight of sulfonated fullerene ferric salt (fullerene sulfonic acid ferric salt) as a dopant and oxidant in a butyl alcohol solvent A chemical polymerization solution is prepared by mixing a solution in which is dissolved. Note that the fullerenes above fullerene C60 is employed, sulfonated fullerene ferric salt is represented by the chemical structural formula _{Fe (C60-O-SO 3} ) 3. Then, after the capacitor element 1 preheated at a temperature of 100 ° C. or higher is immersed in this chemical polymerization solution, the monomer (monomer) is oxidatively polymerized by performing a heat treatment at a temperature of 200 ° C. or higher, and the capacitor element 1 A conductive polymer cathode layer made of 3,4-ethylenedioxythiophene is formed with a thickness of about 40 μm between the two electrode foils. In this case, the conductive polymer cathode layer contains sulfonated fullerene C60 (sulfonated fullerene C60 bonded to the polymer skeleton of the conductive polymer cathode layer and sulfonated fullerene C60 dispersed in the conductive polymer cathode layer). It is.

  And the solid electrolytic capacitor A in an Example is manufactured through the above-mentioned process 3-process 7.

(Comparative example)
In a comparative example, a monomer solution of 3,4-ethylenedioxythiophene, a solution in which 40% by weight of p-toluenesulfonic acid ferric salt as a dopant and oxidant is dissolved in a butyl alcohol solvent, A solid electrolytic capacitor X was produced in the same manner as in the example except that the conductive polymer cathode layer was formed by performing oxidative polymerization using a chemical polymerization solution mixed with the above. This p-toluenesulfonic acid corresponds to a conventional aromatic sulfonic acid.

(Evaluation)
Each solid electrolytic capacitor was evaluated for capacitance (C) and equivalent series resistance (ESR). The capacitance was measured by applying an AC rated voltage of 120 Hz to each solid electrolytic capacitor, and the equivalent series resistance was measured by applying an AC rated voltage of 100 kHz to each electrolytic capacitor. Each evaluation was performed before the heat resistance test (initial state) and after a lapse of 1000 hours by applying a rated voltage of 4 V in a thermostat holding a solid electrolytic capacitor at 150 ° C. as a heat resistance test.

  Table 1 shows the evaluation results of capacitance and equivalent series resistance in each solid electrolytic capacitor. Each characteristic value is an average of 20 samples.

  The capacitance change (C change) and equivalent series resistance change (ESR change) are calculated by the following formulas (1) and (2) using respective characteristic values before and after the heat resistance test.

Capacitance change (%) = (capacitance difference ΔC before and after heat resistance test / capacitance C before heat resistance test) × 100 (1)
Equivalent series resistance change (times) = (Equivalent series resistance after heat resistance test / Equivalent series resistance before heat resistance test) (2)

  As shown in Table 1, in the example (solid electrolytic capacitor A), compared to the conventional comparative example (solid electrolytic capacitor X), the change (deterioration) in capacitance and equivalent series resistance due to the heat resistance test is suppressed to a small extent. Has been. This is because the sulfonated fullerene C60 bonded to the polymer skeleton of the conductive polymer cathode layer and the sulfonated fullerene C60 dispersed in the conductive polymer cathode layer are contained in the conductive polymer cathode layer ( a) Compared to a conductive polymer cathode layer containing an aromatic sulfonic acid, the heat-resistant polymer cathode layer has a heat-resistant sulfonated fullerene C60 contained as a dopant in the conductive polymer cathode layer. (B) Fullerene C60 as a radical scavenging action as an antioxidant rather than as a dopant (function to supplement the conductive polymer to be decomposed without being able to withstand heat and suppress decomposition) This is presumably because the heat resistance of the conductive polymer cathode layer has been improved.

  From the above, in order to improve the heat resistance of the solid electrolytic capacitor, a conductive polymer is used by using a ferric salt of sulfonated fullerene C60 as a dopant and an oxidizing agent when the conductive polymer cathode layer is subjected to oxidative polymerization. It can be seen that it is effective to add fullerene C60 (fullerene C60 bonded to the polymer skeleton of the conductive polymer cathode layer and fullerene C60 dispersed in the conductive polymer cathode layer) to the cathode layer.

  According to the solid electrolytic capacitor and the manufacturing method thereof according to the first embodiment of the present invention, the following effects can be obtained.

  (1) Since fullerene C60 has a radical scavenging action and suppresses decomposition of the conductive polymer due to heat load, in the conductive polymer cathode layer containing the fullerene compound (sulfonated fullerene), the conventional aromatic Compared to the conductive polymer cathode layer to which sulfonic acid is added, its heat resistance is improved. As a result, a solid electrolytic capacitor with improved heat resistance can be obtained.

  (2) A chemical polymerization solution in which a monomer solution to be a conductive polymer and a solution in which a compound of a sulfonated fullerene and an oxidizing metal as a dopant and oxidant is dissolved in an alcohol solvent are mixed. By conducting oxidative polymerization, sulfonated fullerene (sulfonated fullerene bonded to the polymer skeleton of the conductive polymer cathode layer and sulfonated fullerene dispersed in the conductive polymer cathode layer) can be easily converted into the conductive polymer. It can be included in the cathode layer.

  (3) A capacitor in a chemical polymerization solution obtained by mixing a monomer solution to be a conductive polymer and a solution in which a compound of a sulfonated fullerene and an oxidizing metal as a dopant and oxidant is dissolved in an alcohol solvent. Since the element 1 is immersed and the conductive polymer cathode layer is formed by oxidative polymerization inside the capacitor element 1, a sulfonated fullerene having a large molecular weight and high heat resistance can act as a dopant. Compared to a dopant (for example, aromatic sulfonic acid), the heat resistance of the conductive polymer cathode layer can be further improved. As a result, the heat resistance of the solid electrolytic capacitor can be further improved.

  (4) As a compound of a sulfonated fullerene and an oxidizing metal, a fullerene having another structure (for example, for example, by adopting a ferric salt of sulfonated fullerene C60 that can be produced at low cost) Compared to the case of using a ferric salt of fullerene C70 or the like, a conductive polymer cathode layer with improved heat resistance can be formed at low cost.

  (5) By using an alcohol solvent as the solvent in the chemical polymerization solution used for the oxidation polymerization, the wettability with respect to the base substrate (dielectric film formed on the anode foil 2) is increased, and the conductive polymer cathode. Since the adhesion between the layer and the base substrate is improved, the heat resistance of the conductive polymer cathode layer can be further improved.

  (6) By using a polythiophene-based material as a conductive polymer, a conductive polymer cathode layer having a higher decomposition temperature and higher structural stability against applied voltage is formed compared to a polypyrrole-based material or a polyaniline-based material. be able to.

  (7) The capacitor element 1 is made of a sintered body by adopting an anode foil 2 on which a dielectric film is formed and a cathode foil 3 facing the anode foil 2 via a separator paper 4. Compared to a capacitor element formed using an anode body and a capacitor element formed using an anode body made of a metal plate, the capacitor element can be easily manufactured. For this reason, cost reduction of the solid electrolytic capacitor with improved heat resistance can be realized.

  (8) According to the manufacturing method of 1st Embodiment, a suitable solid electrolytic capacitor as described in said (1)-(7) can be manufactured.

(Second Embodiment)
Next, a dielectric film (dielectric layer) and the above-mentioned conductive polymer cathode layer (polymer skeleton of the conductive polymer cathode layer) are formed on the surface of an anode body made of a sintered body of metal particles having a valve action. A solid electrolytic capacitor employing a capacitor element in which a conductive polymer cathode layer containing a fullerene compound bonded to a conductive polymer cathode and a fullerene compound dispersed in a conductive polymer cathode layer) and a cathode lead layer are sequentially formed is described. To do.

  FIG. 3 is a schematic cross-sectional view of a solid electrolytic capacitor according to a second embodiment of the present invention.

  As shown in FIG. 3, the solid electrolytic capacitor according to the second embodiment is formed on an anode body 21 made of a sintered body of metal particles having a valve action from which an anode lead 21 a is led out, and on the surface of the anode body 21. Dielectric layer 22, conductive polymer cathode layer 23 formed on dielectric layer 22, and cathode lead layer (conductive carbon layer 24a formed on conductive polymer cathode layer 23) And a laminated film 24 of a silver paste layer 24b). The conductive polymer cathode layer 23 employs the same conductive polymer as in the first embodiment, and a fullerene compound (for example, sulfonated fullerene C60) is added therein. A flat cathode terminal 27 is joined to the cathode lead layer 24 of the capacitor element 1a via a conductive adhesive (not shown), and a flat anode terminal 26 is joined to the anode lead wire 21a. Yes. And the mold exterior body 28 which consists of an epoxy resin etc. is shape | molded in the form from which the anode terminal 26 and a part of cathode terminal 27 were pulled out outside like FIG.

  The conductive polymer cathode layer 23 is formed by the same method (step 2) as in the first embodiment. That is, a monomer (monomer) solution that becomes a conductive polymer, and a compound of a fullerene compound and a metal having an oxidizing action as a dopant and oxidant in an alcohol solvent (for example, a ferric salt of sulfonated fullerene C60) A chemical polymerization solution is prepared by mixing a solution in which is dissolved. Thereafter, the capacitor element 1a is immersed in this chemical polymerization solution, and the conductive polymer cathode layer 23 is formed on the surface of the dielectric layer 22 in the capacitor element 1a by oxidative polymerization. At this time, the reaction is facilitated by heat treatment to raise the temperature. In addition, for the formation of the conductive polymer cathode layer, an electrolytic polymerization method can be employed.

  According to the solid electrolytic capacitor and the manufacturing method thereof according to the second embodiment of the present invention, the following effects can be obtained in addition to the effects (1) to (6).

  (9) Compared to a solid electrolytic capacitor having a wound capacitor element (first embodiment) and a solid electrolytic capacitor having a capacitor element formed using an anode body made of a metal plate (third embodiment). Therefore, it is possible to easily reduce the size and increase the capacity. In particular, when the capacitance is constant, the solid electrolytic capacitor with improved heat resistance can be reduced in size.

  (10) According to the manufacturing method of the second embodiment, a suitable solid electrolytic capacitor as described in (1) to (6) and (9) above can be manufactured.

(Third embodiment)
Next, on the surface of the metal plate having a valve action, a dielectric film (dielectric layer), the above-described conductive polymer cathode layer (fullerene compound bonded to the polymer skeleton of the conductive polymer cathode layer, and conductive A solid electrolytic capacitor using a capacitor element in which a conductive polymer cathode layer containing a fullerene compound dispersed in a conductive polymer cathode layer) and a cathode lead layer are sequentially formed will be described.

  FIG. 4 is a schematic cross-sectional view showing the configuration of the multilayer solid electrolytic capacitor according to the third embodiment, and FIG. 5 is a schematic cross-sectional view of a capacitor element used in the multilayer solid electrolytic capacitor of FIG.

As shown in FIG. 4, the multilayer solid electrolytic capacitor according to the third embodiment includes a capacitor element 1 b that is stacked in a plurality (four in this example), and has an external lead terminal at the center of the stacked state. A functioning lead frame (anode terminal 36 and cathode terminal 37) is attached. The laminated capacitor element 1b, the anode terminal 36, and the cathode terminal 37 are covered with a mold exterior body 38 in such a manner that a part of the anode terminal 36 and the cathode terminal 37 is drawn to the outside in opposite directions. It is.

  As shown in FIG. 5, the capacitor element 1b has a dielectric layer 32, a conductive polymer cathode layer 33, and a cathode lead layer on the surface of a metal plate (metal single plate) 31 having a valve function as an anode body. 34 are sequentially formed. The dielectric layer 32 is composed of a dielectric made of an oxide of the metal plate 31. The conductive polymer cathode layer 33 employs the same conductive polymer as in the first embodiment, and contains a fullerene compound (for example, sulfonated fullerene C60). The cathode lead layer 34 is composed of a laminated film of a conductive carbon layer 34a and a silver paste layer 34b. The portion where the conductive polymer cathode layer 33 and the cathode lead layer 34 are formed on the dielectric layer 32 becomes the cathode portion 42, and the conductive polymer cathode layer 33 and the cathode lead layer 34 are not formed. The portion becomes the anode portion 41. Then, as shown in FIG. 4, a plurality of capacitor elements 1 b having such a structure are stacked on the lead frame (the anode terminal 36 and the cathode terminal 37) (two in each case on the upper and lower surfaces), and the anode portion 41. And the anode terminal 36 and the adjacent anode part 41 are resistance-welded, and the cathode part 42 and the cathode terminal 37 and the adjacent cathode part 42 are bonded and fixed together with the conductive adhesive 35 to obtain a multilayer solid electrolytic capacitor. Is formed.

  The conductive polymer cathode layer 33 is formed by the same method (step 2) as in the first embodiment. That is, a monomer (monomer) solution that becomes a conductive polymer, and a compound of a fullerene compound and a metal having an oxidizing action as a dopant and oxidant in an alcohol solvent (for example, a ferric salt of sulfonated fullerene C60) A chemical polymerization solution is prepared by mixing the solution in which the solution is dissolved. Thereafter, the capacitor element 1b is immersed in this chemical polymerization solution, and the conductive polymer cathode layer 33 is formed on the surface of the dielectric layer 32 in the capacitor element 1b by oxidative polymerization. At this time, it becomes easy to react by the heat treatment which raises temperature.

  According to the solid electrolytic capacitor and the manufacturing method thereof according to the third embodiment of the present invention, the following effects can be obtained in addition to the effects (1) to (6).

  (11) A solid electrolytic capacitor having a wound capacitor element (first embodiment) or a solid electrolytic capacitor having a capacitor element formed using an anode body made of a sintered body of metal particles (second embodiment) Compared to the embodiment, the equivalent series resistance (ESR) and the effective series inductance (ESL) can be reduced.

  (12) According to the manufacturing method of the third embodiment, a suitable solid electrolytic capacitor as described in (1) to (6) and (11) above can be manufactured.

  The present invention is not limited to the above-described embodiment, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. Embodiments to which such a modification is added Can also be included in the scope of the present invention.

  In the first embodiment, the example in which the plastic seat plate is attached to the upper part of the solid electrolytic capacitor after sealing with the sealing rubber is shown, but the present invention is not limited to this. For example, the seat plate may not be provided. Also in this case, the above effect can be enjoyed.

  In the first embodiment, the capacitor element has a chip type in which two electrode terminals (anode lead wire and cathode lead wire) are bent. However, the present invention is not limited to this. For example, it may be a radial lead type in which the electrode terminal is projected as it is without being bent. Also in this case, the above effect can be enjoyed.

  In the above embodiment, when forming the conductive polymer cathode layer containing the fullerene compound (fullerene compound bonded to the polymer skeleton of the conductive polymer cathode layer and fullerene compound dispersed in the conductive polymer cathode layer). , Formed by using a chemical polymerization solution in which a monomer solution to be a conductive polymer and a solution of a sulfonated fullerene and an oxidizing metal compound dissolved in an alcohol solvent as a dopant and oxidant are mixed However, the present invention is not limited to this. For example, a monomer solution that becomes a conductive polymer, a compound of a sulfonated fullerene and an oxidizing metal as a dopant and oxidizing agent in an alcohol solvent, an aromatic sulfonic acid and an oxidizing metal You may form using the chemical polymerization liquid which mixed the solution which melt | dissolved the compound. In this case, the same effect can be enjoyed.

1 is a schematic cross-sectional view showing a configuration of a solid electrolytic capacitor according to a first embodiment of the present invention. The disassembled perspective view of the capacitor | condenser element which comprises the solid electrolytic capacitor of FIG. The schematic sectional drawing of the solid electrolytic capacitor which concerns on 2nd Embodiment of this invention. The schematic sectional drawing of the solid electrolytic capacitor which concerns on 3rd Embodiment of this invention. The schematic sectional drawing of the capacitor | condenser element used for the solid electrolytic capacitor of FIG.

Explanation of symbols

  1 Capacitor Element, 2 Anode Foil, 3 Cathode Foil, 4 Separator Paper, 5 Winding Tape, 6 Lead Tab Terminal, 7 Anode Lead Wire, 8 Cathode Lead Wire, 9 Case, 10 Sealing Rubber, 11 Seat Plate, 12 Electrode Terminal.

Claims (5)

In the solid electrolytic capacitor in which the dielectric layer and the conductive polymer cathode layer are sequentially formed on the surface of the anode body,
The conductive polymer cathode layer includes a fullerene compound bonded to a polymer skeleton of the conductive polymer cathode layer and a fullerene compound dispersed in the conductive polymer cathode layer. Electrolytic capacitor.   The solid electrolytic capacitor according to claim 1, wherein the fullerene compound is composed of a sulfonated fullerene.   The solid electrolytic capacitor according to claim 1, wherein the conductive polymer cathode layer is polythiophene or a derivative thereof. In a method for producing a solid electrolytic capacitor in which a dielectric layer and a conductive polymer cathode layer are sequentially formed on the surface of an anode body,
As a dopant and oxidant when forming the conductive polymer cathode layer by oxidative polymerization, a compound of a fullerene compound and an oxidizing metal is dissolved in a solvent to be used in the conductive polymer cathode layer. A method for producing a solid electrolytic capacitor comprising: containing the fullerene compound bonded to a polymer skeleton of the conductive polymer cathode layer; and the fullerene compound dispersed in the conductive polymer cathode layer.   The method for producing a solid electrolytic capacitor according to claim 4, wherein the conductive polymer cathode layer is formed using an alcohol-based solvent as a solvent for the dopant and oxidizing agent.

Images