JP2009099652A - Solid electrolytic capacitor, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor used for various kinds of pieces of electronic equipment etc., the solid electrolytic capacitor being inexpensive and having high performance. <P>SOLUTION: The solid electrolytic capacitor comprises an element 5 formed by laminating an anode foil 1 and a cathode foil 3 with a separator 4 interposed therebetween and a conductive polymer solid electrolyte 6 provided between the anode foil 1 and cathode foil 3 of the element 5 in an impregnation state, wherein PET (polyethylene terephthalate) is used for the separator 4 and PSSH (polystyrenesulfonic acid) is added to the conductive polymer solid electrolyte 6 to achieve the high-performance solid electrolytic capacitor which has higher capacity, lower ESR, and a higher breakdown voltage. Further, the solid electrolytic capacitor can be provided at a reduced cost price without adding any manufacturing process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor using a conductive polymer as a solid electrolyte among capacitors used in various electronic devices.

  In response to the higher frequency of electronic equipment, electrolytic capacitors, which are one of the electronic components, have been demanded for large-capacity electrolytic capacitors that have better impedance characteristics in the high frequency region than before, and meet these requirements. Therefore, various solid electrolytic capacitors using a conductive polymer having high electrical conductivity as a solid electrolyte have been studied.

  In addition, in response to the demand for a large capacity, a wound form (anode foil and cathode foil are wound with a separator interposed therebetween), which is structurally easy to increase the capacity compared to the case of laminating electrode foils. Solid electrolytic capacitors using a conductive polymer of a structure) as a solid electrolyte have been commercialized, and since such solid electrolytic capacitors have particularly excellent high frequency characteristics in addition to lifetime and temperature characteristics, Widely used in personal computer power circuits and the like.

  In addition, in a solid electrolytic capacitor having such a wound structure, it is used as a separator used to avoid contact between the anode foil and the cathode foil in an electrolytic capacitor using a conventional driving electrolyte as an electrolyte. So-called electrolytic paper made of manila hemp or kraft paper, glass fiber non-woven fabric, non-woven fabric mainly composed of resin by dry melt blow method, and the like are used.

  Furthermore, a capacitor element is formed by using a separator containing polyvinyl alcohol, and the capacitor element is impregnated with a solution of a boric acid compound, whereby a combined body composed of a compound having a vinyl group and a boric acid compound. A technique has been proposed in which a high withstand voltage is achieved by generating and containing it in a capacitor element.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2003-1000055 A1

  However, in the conventional solid electrolytic capacitor described above, a high withstand voltage is achieved by including a combined body composed of a compound having a vinyl group and a boric acid compound in a capacitor element using a separator containing polyvinyl alcohol. However, such a configuration requires a step of impregnating the capacitor element with a solution of a boric acid compound, resulting in a problem that productivity is lowered and cost is increased.

  Furthermore, along with the downsizing and high performance of electronic devices and the like in which such a solid electrolytic capacitor is used, further increase in capacity, low ESR, high withstand voltage, etc. of the solid electrolytic capacitor are required. There existed a subject that the improvement for meeting such a request | requirement was required.

  The present invention solves such conventional problems, and provides a solid electrolytic capacitor and a method for manufacturing the same capable of realizing further higher capacity, lower ESR, higher withstand voltage, and lower cost. It is intended to provide.

  In order to solve the above problems, the present invention provides an element in which an anode foil and a cathode foil are laminated or wound with a separator interposed therebetween, and a conductive polymer impregnated between the anode foil and the cathode foil of the element. The solid separator is made of PET (polyethylene terephthalate) as the separator, and PSSH (polystyrene sulfonic acid) is added to the conductive polymer solid electrolyte.

  In addition, as a method for producing this solid electrolytic capacitor, a step of producing an element by laminating or winding an anode foil and a cathode foil with a PET (polyethylene terephthalate) separator interposed therebetween, and a heterocyclic type And at least a step of forming a solid electrolyte of polyethylene dioxythiophene between the anode foil and the cathode foil by immersing the element in a polymerization solution comprising ethylenedioxythiophene as a monomer and an oxidizing agent solution and chemically polymerizing the element. In addition, PSSH (polystyrene sulfonic acid) is added to the oxidant solution constituting the polymerization solution.

  As described above, the solid electrolytic capacitor according to the present invention has PSSH (polystyrene sulfonic acid) as a solid electrolyte made of a conductive polymer impregnated between an anode foil and a cathode foil of an element using PET (polyethylene terephthalate) as a separator. The effect of being able to provide a high-performance solid electrolytic capacitor with high capacity, low ESR, and high withstand voltage, and can be provided at low cost without adding a manufacturing process. It is obtained.

(Embodiment)
Hereinafter, the invention described in the entire claims of the present invention will be described by using embodiments.

  FIG. 1 is a partially cutaway perspective view showing a configuration of a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is an enlarged conceptual view of a main part of an element used in the solid electrolytic capacitor. 1 and FIG. 2, an anode foil made of an aluminum foil, in which a roughened layer is formed by etching the surface, and a dielectric oxide film layer 2 is formed on the roughened layer by chemical conversion, 3 is a cathode foil made of an aluminum foil, 4 is a separator made of 100% PET (polyethylene terephthalate, hereinafter referred to as PET), and the separator 4 is interposed between the anode foil 1 and the cathode foil 3. The element 5 is configured by winding.

  In the conceptual diagram of the element 5 shown in FIG. 2, the dielectric oxide film layer 2 formed on the surface of the anode foil 1 is illustrated only on one side in order to make the configuration easier to understand. However, it is formed on both sides.

  6 is a solid electrolyte made of a conductive polymer formed by impregnating the separator 4 disposed between the anode foil 1 and the cathode foil 3 of the element 5, and 7 and 8 are the anode foil 1 and the cathode foil. 3 is an anode lead wire and a cathode lead wire which are respectively joined to the lead wire 3 and pulled out to the outside, and 9 is a bottomed cylindrical aluminum case 10 containing the element 5 to which the anode lead wire 7 and the cathode lead wire 8 are joined. It is a sealing member made of resin vulcanized butyl rubber having a hole through which the anode lead wire 7 and the cathode lead wire 8 are inserted and sealing the opening of the aluminum case 9.

  The separator 4 made of 100% PET is improved in acid resistance with respect to a strongly acidic polymerization solution and heat resistance compared to generally used olefins and vinylon. This is because it has the characteristics of excellent reliability in a high temperature and high withstand voltage environment.

  The solid electrolyte 6 made of the conductive polymer was added with ethylenedioxythiophene monomer, p-nitrophenol (for improving heat resistance), and PSSH (polystyrene sulfonic acid, hereinafter referred to as PSSH). A solid electrolyte 6 of polyethylene dioxythiophene containing PSSH is formed by immersing the element 5 in a polymerization solution composed of an ethanol solution of ferric p-toluenesulfonate to chemically polymerize the element, and the PSSH. Is used because of the improvement in impregnation property due to the effect of surface activity and the SP value, and better adhesion to separators, anode foils and cathode foils compared to polyethylene dioxythiophene alone. Specific examples will be described below.

Example 1
A separator made of 100% PET (density: 0.45 g / cm ³ ) is interposed between an aluminum anode foil whose surface is roughened and a dielectric oxide film layer is formed, and an aluminum cathode foil. The element was produced by winding in a wet state, and this element was immersed in a polymerization solution consisting of an ethylene solution of ethylene dioxythiophene monomer and ferric p-toluenesulfonate containing 5% p-nitrophenol. Then, an element (φ8 × L10 mm) in which a solid electrolyte of polyethylene dioxythiophene was formed was produced by chemical polymerization.

(Example 2)
Example 1 except that a polymerization solution with 1% (solid content) of PSSH added to an ethanol solution of ferric p-toluenesulfonate containing 5% of p-nitrophenol constituting the polymerization solution was used. Thus, an element was produced.

(Comparative Example 1)
An element was produced in the same manner as in Example 1 except that an element was produced using a separator containing PVA (polyvinyl alcohol, hereinafter referred to as PVA) in PET.

(Comparative Example 2)
As a separator, an element was prepared using a separator containing PVA in PET, and 1% PSSH was added to an ethanol solution of ferric p-toluenesulfonate to which 5% of p-nitrophenol constituting the polymerization solution was added. (Solid content) A device was fabricated in the same manner as in Example 1 except that the added polymerization solution was used.

  The results of measuring the capacitance, tan δ, ESR, and withstand voltage characteristics of Examples 1 and 2 and Comparative Examples 1 and 2 according to the present embodiment thus obtained are shown in Table 1.

  As is clear from (Table 1), the solid electrolytic capacitor according to this embodiment uses a separator made of 100% PET, and has a configuration in which PSSH is added to a solid electrolyte made of a conductive polymer (those having a configuration according to Example 2). ), It can be seen that excellent performance is exhibited in a well-balanced manner in all of capacitance, tan δ, ESR, and withstand voltage characteristics.

  In Comparative Examples 1 and 2, although excellent performance was exhibited in capacitance, tan δ, and ESR, the withstand voltage characteristic was low, and a solid made of a conductive polymer. The effect of adding PSSH to the electrolyte is not seen.

  Therefore, the solid electrolytic capacitor according to the present invention does not need to add a step of impregnating the capacitor element with a solution of a boric acid compound, unlike the technique disclosed in the patent document described in the background section. There is a special effect that a high-performance solid electrolytic capacitor can be provided at low cost without lowering productivity.

  In the present embodiment, a polymerization solution having 1% (solid content) PSSH added to an ethanol solution of ferric p-toluenesulfonate added with 5% of p-nitrophenol constituting the polymerization solution is used. As described above by way of example, the amount of PSSH added is not limited to this, but adding 2% or more is not preferable because ESR tends to deteriorate, and if the amount added is greatly reduced Since the effect is reduced, it is not preferable.

  In the present embodiment, the anode foil and the cathode foil have been described using the example in which the element is formed by winding the separator foil therebetween, but the present invention is limited to this. Instead, it may be an element formed by laminating an anode foil and a cathode foil with a separator interposed therebetween.

  Further, in the present embodiment, the description has been made with the example using the aluminum anode foil having the surface roughened and the dielectric oxide film layer formed thereon, and the aluminum cathode foil. The cathode foil is not limited, and a foil of nickel, titanium, carbon or the like may be used, and the same effects as those obtained when an aluminum cathode foil is used can be obtained.

  The solid electrolytic capacitor according to the present invention has an effect of being inexpensive and having high performance, and is useful as a capacitor in all fields.

1 is a partially cutaway perspective view showing a configuration of a solid electrolytic capacitor according to an embodiment of the present invention. Conceptual diagram enlarging the main part of the element used in the solid electrolytic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anode foil 2 Dielectric oxide film layer 3 Cathode foil 4 Separator 5 Element 6 Solid electrolyte 7 Anode lead wire 8 Cathode lead wire 9 Aluminum case 10 Sealing member

Claims (3)

An element formed by laminating or winding an anode foil and a cathode foil with a separator interposed therebetween, and a solid electrolyte composed of a conductive polymer impregnated between the anode foil and the cathode foil of the element; A solid electrolytic capacitor comprising an exterior member containing or covering these, wherein PET (polyethylene terephthalate) is used as the separator, and PSSH (polystyrene sulfonic acid) is added to a solid electrolyte comprising a conductive polymer. The solid electrolytic capacitor according to claim 1, wherein the separator constituting the element is a PET (polyethylene terephthalate) 100%. A step of fabricating an element by laminating or winding an anode foil and a cathode foil with a PET (polyethylene terephthalate) separator interposed therebetween, and comprising an ethylenedioxythiophene as a heterocyclic monomer and an oxidizing agent solution And at least a step of forming a solid electrolyte of polyethylenedioxythiophene between the anode foil and the cathode foil by immersing the element in a polymerization solution and chemically polymerizing the solution. PSSH is added to the oxidant solution constituting the polymerization solution. A method for producing a solid electrolytic capacitor in which (polystyrenesulfonic acid) is added.

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