JP2010245150A - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide a solid electrolytic capacitor having an excellent capacitance characteristic and ESR characteristic by increasing the amount of conductive polymer formed.
A capacitor element 10 formed by winding an anode foil 1 made of aluminum on which a dielectric oxide film is formed and a cathode foil 2 made of aluminum through a separator 3, and the separator 3 having a fiber diameter of 1 μm. It is composed of the following fibers, and a conductive polymer 4 in the form of a film of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate is formed between the fibers of the separator 3 and the fibers. A solid electrolytic capacitor is provided.
[Selection] Figure 1

Description

  The present invention relates to a wound solid electrolytic capacitor used in various electronic devices and a method for manufacturing the same.

  Electrolytic capacitors are widely used as electronic components constituting various electronic devices. Conventionally, electrolytic capacitors using an electrolytic solution as an electrolyte have been used. However, with the increase in the frequency of electronic equipment, electrolysis with a large capacity and low equivalent series resistance (hereinafter referred to as ESR) excellent in impedance characteristics in a high frequency region. Capacitors have been demanded.

  Recently, in order to reduce the ESR in the high frequency region, a solid electrolytic capacitor using a solid electrolyte such as a conductive polymer having a high electric conductivity in the high frequency region has been studied. In addition, in response to the demand for higher capacity, compared to the case of laminating electrode foils (laminated type), it is easier to increase the capacity (anode foil and cathode foil are wound via a separator). Of the structure) has been commercialized. Compared to the laminated type, the wound shape as the shape of the capacitor has the advantage that the capacity of the capacitor can be increased while the area and size of the electrode foil are reduced. Such a wound solid electrolytic capacitor has excellent life and temperature characteristics. In addition, since the high frequency characteristics are very excellent, it is widely used in power supply circuits of personal computers.

  Further, the higher the voltage applied to the dielectric that constitutes the solid electrolytic capacitor, the more electric charge can be stored on the surface of the dielectric. Therefore, it is also required that the voltage applicable to the solid electrolytic capacitor is high, that is, so-called rated voltage is increased. For this purpose, there is a need for a so-called short-circuit resistance that does not cause a short circuit, even when a high voltage is applied to the solid electrolytic capacitor.

  In the wound structure, it is essential to interpose a separator in order to avoid contact between the anode foil and the cathode foil. As the material of the separator, a carbonized electrolytic paper (hereinafter, carbonized paper) or a non-woven fabric is used. Electrolytic paper materials include Manila hemp and kraft paper. Glass fiber and synthetic resin are used for the material of the nonwoven fabric.

  As a method of forming this conductive polymer in a wound capacitor element, an anode foil and a cathode foil are wound through a separator to form a wound capacitor element, and then the wound capacitor element is polymerized. There is a method of immersing in a mixed solution of a polymerizable monomer and an oxidizing agent, drying and heating, or a method of separately immersing the wound capacitor element in the polymerizable monomer solution and the oxidizing agent solution. . As the polymerizable monomer, polypyrrole, polythiophene, polyaniline, polyethylenedioxythiophene (hereinafter, PEDOT) or the like is used. Examples of the oxidizing agent include 1,5-naphthalenedisulfonic acid, benzenesulfonic acid, paratoluenesulfonic acid (hereinafter, p-TSA). In this method, after immersing the wound capacitor element in the polymerizable monomer solution, and subsequently immersing the wound capacitor element in an oxidant solution, the inside of the wound capacitor element penetrated. The polymerizable monomer comes into contact with the oxidizing agent. Thus, the polymerizable monomer is chemically polymerized, and a conductive polymer can be uniformly formed between the anode foil and the cathode foil (Patent Documents 1 to 3).

  As a method of forming this conductive polymer in a wound capacitor element, an anode foil and a cathode foil are wound through a separator to form a wound capacitor element, and then the wound capacitor element is A method of immersing in a mixed solution of a polymerizable monomer and the oxidizing agent, drying and heating, or a method of separately immersing the wound capacitor element in the polymerizable monomer solution and the oxidizing agent solution There is.

  Further, as a method for forming the conductive polymer, there is also known a method in which polypyrrole fine particles or PEDOT fine particles are dispersed in a dispersion medium such as water and a fine particle dispersion is applied onto an electrode foil. In this method, the wound capacitor element is immersed in a fine particle dispersion (in which the dispersion is described as a solution in Patent Document 4) and an additive is added to form a film-like conductive material on the separator. Form a polymer. Here, phosphoric acid or phosphoric acid ester having a function of forming an oxide film is used as an additive.

  In the solid electrolytic capacitor manufactured by the above method, it is said that an oxide film is re-formed on the defective portion of the dielectric oxide film of the anode foil, and a solid electrolytic capacitor having high pressure resistance can be obtained (Patent Document 4). .

Furthermore, as an additive described in Patent Document 4, there is a method of using a polymer precursor having insulating properties. According to this method, it is said that a solid electrolytic capacitor with high pressure resistance can be obtained by insulating a film defect portion (for example, Patent Document 5).
JP 2007-273751 A Japanese Patent Laid-Open No. 10-340829 Japanese Patent No. 3606137 Japanese Patent No. 3551038 JP 2003-1000056 A1

  In the solid electrolytic capacitor of Patent Document 1, since the fiber diameter of the mixed paper constituting the separator is several μm and non-uniform, defects in the separator occur when the density of the separator is reduced or the thickness is reduced. As a result, when the rated voltage of the solid electrolytic capacitor is 16 V or more, there is a problem that the short-circuit rate increases.

  Further, the solid electrolytic capacitor of Patent Document 2 has a wide distribution of the fiber diameter of the vinylon fiber of the separator as 2 to 8 μm, and the dissolution and removal rate of the binder is not constant, so that the characteristics of the obtained solid electrolytic capacitor vary. There are challenges.

  Further, the solid electrolytic capacitor of Patent Document 3 also has a problem in further reducing the ESR of the solid electrolytic capacitor because the fiber diameter of the separator is large.

  The method of chemically oxidatively polymerizing polymerizable monomers disclosed in Patent Documents 1 to 3 has a problem that the withstand voltage of the solid electrolytic capacitor is lowered because the oxidant solution corrodes the dielectric oxide film of the anode foil. .

  FIG. 6 shows a conductive polymer formed on the separator by the chemical oxidative polymerization. In the figure, it can be seen that the conductive polymer particles agglomerate and voids exist throughout the separator. The presence of this void makes it difficult to further reduce the ESR of the solid electrolytic capacitor.

  Further, the solid electrolytic capacitor of Patent Document 4 is obtained by depositing a film-like conductive polymer using an aqueous dispersion liquid such as polypyrrole fine particles and polyethylene dioxythiophene fine particles. Unlike the patent documents 1 to 3, the oxidant solution does not contact the dielectric oxide film of the anode foil in the conductive polymer forming method of the patent document 4. Although the withstand voltage is thereby improved, there is a problem in that the ESR of the solid capacitor is increased because the affinity between water, which is a solvent for the conductive polymer, and the fibers of the separator is not sufficient.

  The solid electrolytic capacitor of Patent Document 5 also has a problem that the ESR of the solid capacitor increases due to the additive although the withstand voltage is improved as in Patent Document 4.

  An object of the present invention is to solve such conventional problems and to provide a solid electrolytic capacitor having excellent ESR characteristics, capacitance characteristics, leakage current characteristics, rated voltage values, and the like.

  In order to solve the above problems, a solid electrolytic capacitor of the present invention is a capacitor element formed by winding an anode foil made of aluminum on which a dielectric oxide film is formed and a cathode foil made of aluminum through a separator; A conductive polymer of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (hereinafter referred to as PEDOT / PSS) is formed on the separator, the separator is formed of fibers having a fiber diameter of 1 μm or less, and fibers In addition, a film-like conductive polymer is deposited between the fibers without a gap.

  In the production method of the present invention, cellulose or resin is dissolved in a solvent, and a DC voltage is applied to a nozzle for injecting this solution to deposit non-fibrillated fibers having a fiber diameter of 1 μm or less to form a separator. A step of forming a capacitor element by interposing and winding the separator between an anode foil and a cathode foil, immersing the capacitor element in a PEDOT / PSS dispersion, and drying the dispersion medium And a step of depositing a film-like conductive polymer between the fibers of the separator and the fibers.

  According to the solid electrolytic capacitor of the present invention, by forming a capacitor element using a separator formed of uniform fibers having a fiber diameter of 1 μm or less, the thickness of the separator can be reduced while keeping the density of the separator low. Thereby, since the PEDOT / PSS conductive polymer is deposited without gaps between the fibers of the separator and the fibers, the conductivity of the separator is improved. As a result, a solid electrolytic capacitor having excellent ESR characteristics and capacitance characteristics can be obtained.

  Further, according to the method for forming a solid capacitor of the present invention, 3,4-ethylenedioxythiophene (hereinafter referred to as EDOT) is added with p-toluenesulfonic acid (hereinafter referred to as pTSA) and subjected to chemical oxidative polymerization, whereby a dispersion of PEDOT / PSS. Get. Next, the dispersion liquid is impregnated into the capacitor element, and then dried to form a film-like conductive polymer on the separator. Through the above steps, a film-like conductive polymer can be formed on the separator without corrosion of the dielectric oxide film of the anode foil. Therefore, a solid electrolytic capacitor having a low leakage current can be obtained, and a capacitor having a high rated voltage can be obtained because of excellent short circuit resistance.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is a partial cross-sectional perspective view showing the configuration of the solid electrolytic capacitor of the present invention, and FIG. 2 is an enlarged partial cross-sectional conceptual view of the main part of the solid electrolytic capacitor. In FIG. 1, the capacitor element 10 is formed by winding an anode foil 1 and a cathode foil 2 through a separator 3.

  The anode foil 1 is made of an aluminum foil having a dielectric oxide film 9 formed by roughening the surface by etching and then anodizing. The cathode foil 2 is made of an aluminum foil whose surface is roughened by an etching process.

  The capacitor element 10 is accommodated in a cylindrical aluminum case 8 with a bottom, and the open end of the aluminum case 8 is led out from each of the anode foil 1 and the cathode foil 2 by a rubber sealing material 7. 5 and the cathode lead 6 are sealed so as to penetrate the sealing material 7.

  In FIG. 2, the conductive polymer 4 fills the space between the anode foil 1 and the cathode foil 2 without any gap. Here, the separator 3 in FIG. 1 serves as an anchor for the conductive polymer 4 and is held between the anode foil 1 and the cathode foil 2. The above configuration constitutes a wound solid electrolytic capacitor.

  FIG. 3 is a planar SEM photograph (× 3000 times) of the separator 3 in the first embodiment. As shown in this figure, the separator 3 according to the first embodiment is formed by depositing long non-fibrillated fibers having a fiber diameter of 1 μm or less, the fiber diameter is uniform, and the fibers of the separator 3 and The conductive polymer 4 can be formed on the separator 3 by impregnating a dispersion of PEDOT / PSS between the fibers and drying.

  Separator 3 used for capacitor element 10 is made of cellulose fiber or polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyacrylonitrile (PAN), aramid, It is at least one synthetic fiber selected from polyimide, nylon, modified PP, modified PE, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE).

  FIG. 4 is a schematic view of a basic apparatus for producing the separator 3 in the first embodiment. The manufacturing method of the separator 3 in this Embodiment 1 is demonstrated using FIG.

  First, a solution in which cellulose or resin is dissolved in an organic solvent or water is prepared, and this solution is poured into the solution tanks 15 and 16. Next, a DC voltage of 10 to 50 kV is applied between the nozzles 13 and 14 connected to the solution tanks 15 and 16 and the current collector plate 12 set on the upper surface of the substrate 11. Next, by ejecting the solution from the nozzles 13 and 14, long fibers having a fiber diameter of 1 μm or less are deposited on the surface of the current collector plate. Finally, an aggregate of long fibers deposited on the upper surface of the current collector plate 12 is molded. Thereafter, saponification or heating is performed according to the application.

  Through the above steps, the separator 3 according to the first embodiment is obtained.

  In addition, the fiber diameter of the fiber which comprises the separator 3 of this Embodiment 1 can obtain arbitrary things by adjusting DC voltage.

  As the cellulose solution, copper ammonia cellulose, cellulose esters such as cellulose nitrate, cellulose acetate, and acetic acid-butyric acid cellulose can be used. The cellulose concentration with respect to the solution is preferably in the range of 5 to 20 wt%.

  Next, a method for producing a copper ammonia cellulose solution will be described. First, regenerated cellulose is added to a solution in which ammonia is dissolved in a copper sulfate solution. Next, it can be prepared by sufficiently stirring and dissolving it, and further adding polyalkylene glycol and a surfactant.

  The resin solution includes polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyacrylonitrile (PAN), aramid, polyimide, nylon, modified PP, A solution comprising at least one resin selected from modified PE, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE), which is dissolved in an organic solvent or water is used.

  Examples of the organic solvent include methyl alcohol, ethyl alcohol, isopropanol, acetone, benzene, toluene, acetonitrile, cyclohexane, propylene carbonate, N-methylpyrrolidine, dimethylacetamide, and the like, which are selected depending on the resin.

  Although the resin is dissolved in an organic solvent or water to form a solution, the resin does not necessarily have to be dissolved in the solvent. For example, a fine resin dispersed in a solvent or an emulsion can be used.

  In the separator of Embodiment 1, the fiber diameter is 1 μm or less, preferably 0.1 to 0.8 μm, and the thickness is 1 to 20 μm, preferably 5 to 15 μm. If the fiber diameter is less than 0.1 μm, sufficient separator strength cannot be obtained, and the capacitor element cannot be formed due to the separator tearing when the capacitor element is formed. On the other hand, when the fiber diameter exceeds 1 μm, the amount of the separator fibers and the conductive polymer deposited between the fibers decreases, and the ESR characteristics of the solid electrolytic capacitor deteriorate. On the other hand, if the thickness of the separator is less than 1 μm, the insulation of the separator is lowered and the voltage resistance of the capacitor element is lowered. Further, if the thickness of the separator exceeds 20 μm, the solid electrolytic capacitor cannot be reduced in size. Moreover, when the distance between the anode and the cathode is increased, the electrical resistance value therebetween increases. As a result, the ESR characteristic of the solid electrolytic capacitor is deteriorated.

The density of the separator of the first embodiment is 0.1 to 1 g / cm ^3, preferably 0.3 to 0.7 g / cm ^3. The weighing is 10 to 70 g / m ² , preferably 30 to 50 g / m ² . If it is less than the lower limit value of the density and weighing shown here, the strength and insulation of the separator are lowered. Further, if the density and the upper limit values of weighing are exceeded, a sufficient amount of conductive polymer is not formed in the separator 3 of the first embodiment. For this reason, the electrical resistance value between the anode and the cathode is increased, so that the ESR characteristic is degraded.

  A method for depositing the conductive polymer 4 on the separator 3 will be described. First, an EDOT solution and a pTSA solution are prepared. Here, pTSA is an oxidant for the chemical oxidative polymerization reaction of EDOT, and at the same time, combines with EDOT after the polymerization reaction to become a dopant. Next, after chemical oxidation polymerization of the EDOT solution, it is mixed with a dispersion medium to prepare a PEDOT / PSS dispersion solution. Hereinafter, this is referred to as a dispersion. Next, the capacitor element 10 is impregnated in this dispersion, and then dried, so that PEDOT / PSS is deposited between the fibers of the separator 3 and the fibers. Through the above steps, the conductive polymer 4 can be applied to the separator 3.

  Here, attaching the conductive polymer to the separator means that the fibers of the separator 3 and the space between the fibers are covered with a thin film film made of PEDOT / PSS. When the state in which the conductive polymer is deposited on the separator 3 is observed, the conductive polymer is attached to the entire separator 3 so as to spread.

  The conductive polymer 4 of the present invention is different in shape from that obtained by the conventional forming methods described in Patent Documents 1 to 3. The conductive polymer formed by the conventional method becomes a particulate film, and the conductive polymer 4 of the present invention becomes a film-like film that is nearly transparent. The preferable thickness is about 0.05 to 5.0 μm, more preferably 0.1 to 1.5 μm.

  As the separator used here, a cellulose-based separator using manila hemp or hemp material and a synthetic fiber separator are well known. They are formed of non-uniform fibers having a fiber diameter of several μm, and since the distance between the fibers is long, the conductive polymer film-like film cannot be held. As a result, only conductive polymer membranes with many defects were obtained, and the solid electrolytic capacitor had poor ESR characteristics.

  In the solid electrolytic capacitor of the present invention, the conductive polymer 4 made of PEDOT / PSS is formed on a separator 3 on which non-fibrillated fibers having a fiber diameter of 1 μm or less are deposited, and the fibers of the separator 3 and its By applying the conductive polymer 4 between the fibers in the form of a film, defects in the conductive polymer film are reduced. As a result, the capacitance of the solid electrolytic capacitor can be increased, and an excellent ESR characteristic and leakage current characteristic can be obtained. Further, when forming the conductive polymer 4 on the separator 3, an anode foil in which the dispersion constitutes the capacitor element 10 can be obtained by using a conductive polymer dispersion whose pH is adjusted to near neutral. Does not corrode. As a result, a solid electrolytic capacitor with low leakage current can be obtained. Moreover, since the obtained solid electrolytic capacitor is excellent in short circuit resistance, a capacitor with a high rated voltage can be obtained.

  Next, specific examples of the present invention will be described, but the present invention is not limited thereto.

Example 1
First, cotton linter was added to a solution in which ammonia was dissolved in a copper sulfate solution (concentration: 10 wt%). This was sufficiently stirred and dissolved, and further 5 wt% of polyalkylene glycol and 0.5 wt% of a surfactant were added to prepare a copper cellulose solution.

Next, a separator was produced using the apparatus shown in FIG. First, the prepared solution was poured into a solution tank. After the injection, an aggregate of long fibers was deposited on the current collector plate by applying a voltage of 20 kV between the nozzle and the current collector plate and spraying the copper cellulose solution toward the current collector plate. The separator A (fiber diameter 0.2 μm, thickness 15 μm, weighing 60 g / m ² ) was produced by molding and heat-treating it at 200 ° C. for 30 minutes.

  Next, the surface of the aluminum foil was roughened by etching. Subsequently, the aluminum foil was subjected to an anodic oxidation treatment at a formation voltage of 32 V for a sufficient time. After anodizing treatment, a dielectric oxide film was formed on the surface, and then cut into strips (65 × 5 mm) to produce an anode foil.

  Next, the aluminum foil different from that used for the anode foil preparation was etched to roughen the surface. Next, it cut | disconnected to strip shape (50x6 mm), and produced the cathode foil.

  After welding the respective leads to the anode foil and the cathode foil prepared earlier, the separator A was interposed between the anode foil and the cathode foil and wound to obtain a capacitor element. When impregnated with 10 wt% ethylene glycol solution, the capacitance value at a frequency of 120 Hz was 100 μF.)

  Subsequently, the capacitor element prepared above was anodized (formation voltage 32 V) for 30 minutes in an aqueous solution of ammonium dihydrogen phosphate, and then heat-treated at 200 ° C.

  Next, EDOT and p-TSA were mixed with ion-exchanged water, and ammonium persulfate and an oxidation catalyst solution of ferric sulfate were added to and stirred in this mixed solution to carry out a chemical polymerization reaction. Next, the obtained reaction solution was centrifuged and salted out to remove unreacted EDOT, PSSA, ammonium persulfate and ferric sulfate. As a result, a conductive polymer dispersion composed of PEDOT / PSS (molecular weight; about 150,000) was produced.

  The capacitor element was impregnated in the conductive dispersion, lifted from the dispersion, and dried at 120 ° C. Thereby, the film-like PEDOT / PSS was deposited on the separator, and a conductive polymer was formed between the anode foil and the cathode foil.

  Subsequently, a capacitor element formed with a film-like conductive polymer was composed of a resin vulcanized butyl rubber sealing material (30 parts butyl rubber polymer, 20 parts carbon, 50 parts inorganic filler. Sealing body hardness: 70 IRHD [international rubber Hardness unit]) and enclosed in a bottomed cylindrical aluminum case. Finally, the opening was sealed by curling treatment to produce a solid electrolytic capacitor (size: diameter 8 mm, height 8 mm).

(Example 2)
In Example 2, a solution in which cellulose acetate was dissolved in diacetone alcohol (cellulose concentration: 10 wt%) was prepared as a solution for producing a separator. Using the solution, an assembly of long fibers was deposited on the current collector plate through the same apparatus and procedure as in Example 1. Next, it was immersed in a caustic soda / methanol solution for alkali saponification. This was molded and subjected to a heat treatment at 200 ° C. for 30 minutes to prepare a separator B (fiber diameter 0.3 μm, thickness 15 μm, weighing 50 g / m ² ). A solid electrolytic capacitor was produced by the same procedure as in Example 1 except that the separator B was used.

Example 3
In Example 3, a solution in which polybutylene terephthalate (PBT) resin (10 wt%) was dissolved in an organic solvent was prepared as a solution for producing a separator. Using the solution, an assembly of long fibers was deposited on the current collector plate through the same apparatus and procedure as in Example 1. This was molded and subjected to a heat treatment at 250 ° C. for 30 minutes to produce a separator C (fiber diameter 0.5 μm, thickness 15 μm, weighing 40 g / m ² ). A solid electrolytic capacitor was produced by the same procedure as in Example 1 except that the separator C was used.

Example 4
In Example 4, a solution in which poly (vinylidene fluoride) (PVDF) resin (10 wt%) was dissolved in an organic solvent was prepared as a solution for producing a separator. Using the solution, an assembly of long fibers was deposited on the current collector plate through the same apparatus and procedure as in Example 1. It was molded and subjected to a heat treatment at 120 ° C. for 20 minutes to produce a separator D (fiber diameter 0.7 μm, thickness 15 μm, weighing 20 g / m ² ). A solid electrolytic capacitor was produced by the same procedure as in Example 1 except that the separator D was used.

(Comparative Example 1)
In Comparative Example 1, a capacitor element was formed using Separator E (fiber diameter 8 μm, thickness 20 μm, weighing 15 g / m ² ) made of cotton linter as a separator. FIG. 5 shows a surface SEM photograph (× 3000 magnification) of the separator E. From this, it was found that the separator E was formed of non-uniform fibers having a fiber diameter of 7 to 10 μm. Next, the manufacturing procedure of the solid electrolytic capacitor of Comparative Example 1 is shown below.

  First, the surface of the aluminum foil was roughened by etching. Subsequently, the aluminum foil was subjected to an anodic oxidation treatment at a formation voltage of 32 V for a sufficient time. After anodizing treatment, a dielectric oxide film was formed on the surface, and then cut into strips (65 × 5 mm) to produce an anode foil.

  Next, the aluminum foil different from that used for the anode foil preparation was etched to roughen the surface. Next, it cut | disconnected to strip shape (50x6 mm), and produced the cathode foil.

  After welding the respective leads to the anode foil and the cathode foil prepared earlier, the separator E was interposed between the anode foil and the cathode foil and wound to obtain a capacitor element (ammonium adipate was added to this capacitor element). When impregnated with 10 wt% ethylene glycol solution, the capacitance value at a frequency of 120 Hz was 75 μF.)

  Next, 1 part of EDOT and 2 parts of p-TSA ferric salt were dissolved in 4 parts of n-butanol to prepare an EDOT / p-TSA ferric salt mixed solution. Next, after the capacitor element was immersed in the mixed solution and pulled up, chemical polymerization was performed at 85 ° C. for 60 minutes, and conductive polymer fine particles made of PEDOT / PSSA were deposited on the separator E. FIG. 6 shows a surface SEM photograph (× 300 times) of the separator E after the conductive polymer fine particles are formed. From this, it was found that the conductive polymer of Comparative Example 1 had voids and was agglomerated in some places. A solid electrolytic capacitor was produced by the above procedure.

(Comparative Example 2)
In Comparative Example 2, a capacitor element was formed using a separator F (fiber diameter 15 μm, thickness 20 μm, weighing 15 g / m ² ) mixed with Manila hemp as a separator. A solid electrolytic capacitor was produced by the same procedure as in Comparative Example 1 except that the capacitor element was formed using the separator F.

(Comparative Example 3)
In Comparative Example 3, a capacitor element was formed using a nonwoven fabric separator G (fiber diameter 10 μm, thickness 20 μm, weigh 10 g / m ² ) prepared by forming a polyethylene terephthalate fiber by a wet method as a separator. A solid electrolytic capacitor was produced by the same procedure as in Comparative Example 1 except that the capacitor element was formed using the separator G.

  Table 1 shows the electrical characteristics of the solid electrolytic capacitors of Examples 1 to 4 and Comparative Examples 1 to 3 of the present invention. As the electrical characteristics of the solid electrolytic capacitor, values of capacitance (measurement frequency 120 Hz), ESR (measurement frequency 100 kHz), and leakage current (2 minutes value after application of the rated voltage 16V) are shown. The left side of Table 1 shows the initial values, and the right side shows the electrical characteristics of the solid electrolytic capacitor after 2000 hours of the high-temperature voltage application test (applying a DC voltage of 16 V to the solid electrolytic capacitor at 105 ° C). It was.

  The number of tests was 50. In addition, the values of capacitance, impedance, and leakage current in Table 1 are shown as average values of samples excluding short products.

  From Table 1, the solid electrolytic capacitors of Examples 1 to 4 exhibited electrical characteristics superior to the solid electrolytic capacitors of Comparative Examples 1 to 3 both at the initial characteristics and after the high temperature voltage application test.

  From the above, it was shown that a solid electrolytic capacitor having excellent capacitance characteristics and ESR characteristics was obtained by constituting the separator of the capacitor element from fibers having a fiber diameter of 1 μm or less.

  Moreover, it was shown that a solid electrolytic capacitor excellent in leakage current characteristics and short-circuit resistance was obtained by removing unreacted EDOT, PSSA, ammonium persulfate and ferric sulfate.

  In Examples 1 to 4, the example using cotton linter, cellulose acetate, PBT resin, and PVDF resin as the material of the separator was described. However, polyimide, polyester such as PET, and fluorine resin such as PTFE may be used. Similar effects can be obtained.

  The present invention relates to a wound solid electrolytic capacitor used in various electronic devices. By providing a solid electrolytic capacitor excellent in capacitance, ESR and leakage current characteristics, and excellent in short-circuit resistance, high frequency and high voltage are provided. It can be applied to electronic parts used in.

The partial cross section perspective view which shows the structure of the solid electrolytic capacitor in Embodiment 1 of this invention The conceptual diagram which expanded the principal part of the capacitor element of FIG. Surface SEM photograph of separator in Embodiment 1 of the present invention Schematic of separator manufacturing apparatus in Embodiment 1 of the present invention Surface SEM photograph of separator in Comparative Example 1 Surface SEM photograph of conductive polymer formed on separator of Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 Anode foil 2 Cathode foil 3 Separator 4 Conductive polymer 5 Anode lead 6 Cathode lead 7 Sealing material 8 Aluminum case 9 Dielectric oxide film 10 Capacitor element 11 Substrate 12 Current collector plate 13, 14 Nozzle 15, 16 Solution tank

Claims (6)

A capacitor element formed by winding an anode foil made of aluminum on which a dielectric oxide film is formed and a cathode foil made of aluminum through a separator, and the separator is made of fibers having a fiber diameter of 1 μm or less, A solid electrolytic capacitor characterized in that a conductive polymer in the form of a film of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate is deposited between the fibers and the fibers. 2. The solid electrolytic capacitor according to claim 1, wherein the separator is formed by dissolving cellulose in a solvent and applying a DC voltage to a nozzle for injecting the solution to deposit long fibers having a fiber diameter of 1 μm or less. The separator is polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyacrylonitrile (PAN), aramid, polyimide, nylon, modified PP, modified PE. At least one resin selected from polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) is dissolved in an organic solvent or water, and a direct current voltage is applied to a nozzle for injecting this solution to obtain a fiber diameter of 1 μm. The solid electrolytic capacitor according to claim 1, which is formed by depositing the following long-fiber non-fibrillated fibers. Forming a separator by preparing a solution in which cellulose or resin is dissolved in an organic solvent or water, applying a direct current voltage to a nozzle for injecting the solution to deposit long fibers having a fiber diameter of 1 μm or less, and the separator A capacitor element is formed by winding a metal foil between an anode foil and a cathode foil, and a conductive polymer dispersion of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate. A method for producing a solid electrolytic capacitor, comprising: dipping the capacitor element and drying to deposit a fiber of the separator and a film-like conductive polymer between the fibers. A step of forming a film-like conductive polymer, which is obtained by adding a polystyrene sulfonic acid dopant and an oxidant to 3,4-ethylenedioxythiophene and subjecting it to chemical oxidative polymerization. 5. The capacitor element is immersed in a conductive polymer dispersion of dioxythiophene) / polystyrene sulfonate, and then dried to deposit a separator fiber and a film-like conductive polymer between the fibers. The manufacturing method of the solid electrolytic capacitor of description. A step of forming a separator, in which a plurality of nozzles each having a fiber diameter of 1 μm or less are prepared by preparing at least two nozzles for injecting a solution and spraying solutions having different resin concentrations for dissolving the resin in an organic solvent or water. The method for producing a solid electrolytic capacitor according to claim 5, wherein the separator is formed by intertwining long fibers having a fiber diameter of 1 μm or less into a three-dimensional structure in which the non-fibrillated fibers are bonded to resin particles.