Electrolytic capacitor and manufacturing method for the same

Abstract

To provide a highly reliable electrolytic capacitor with suppressed acidification of a separator and a manufacturing method for the same.SOLUTION: An electrolytic capacitor has a capacitor element with a positive electrode foil and a negative electrode foil wound via a separator holding a conductive polymer layer. The separator is mainly made of glass fibers with a porosity of 75 to 90 (%).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electrolytic capacitor using a conductive polymer and a method for manufacturing the same. [Background technology]

[0002] An electrolytic capacitor has a structure in which a capacitor element made of, for example, aluminum foil anode and cathode foils wound with a separator interposed therebetween is impregnated with an electrolyte and assembled together with a sealing body into an exterior case. Examples of aluminum electrolytic capacitors using conductive polymers include solid electrolytic capacitors that hold a conductive polymer within the capacitor element, and hybrid electrolytic capacitors that hold a conductive polymer and an electrolyte within the capacitor element (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-59471 A [Patent Document 2] International Publication No. 2017 / 090241 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, separators such as cellulose fibers that have been conventionally used in aluminum electrolytic capacitors that use conductive polymers have low acid resistance and are decomposed by strongly acidic polymers. When manufacturing solid electrolytic capacitors using this type of separator, for example, in the process of chemically polymerizing a monomer with an oxidizing agent to produce a conductive polymer layer, the separator fibers may rapidly deteriorate due to the effects of chemical polymerization.

[0005] In contrast, even if a conductive polymer layer is formed by immersing a capacitor element in a dispersion of a conductive polymer and drying it, the separator rapidly deteriorates due to the elution of the conductive polymer after manufacture. For example, in the case of a hybrid electrolytic capacitor in which a conductive polymer layer is formed using the above-mentioned dispersion, the conductive polymer is likely to dissolve in the electrolyte contained in the separator. The more the electrolyte evaporates, the higher the acidity of the electrolyte becomes due to the conductive polymer eluted from the conductive polymer layer into the electrolyte, and the faster the deterioration of the separator and the promotion of decomposition.

[0006] As the separator becomes acidic and decomposition proceeds, the amount of conductive polymer retained may decrease, leading to an increase in ESR, and the amount of electrolyte retained may decrease, leading to an increase in leakage current.

[0007] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a highly reliable electrolytic capacitor in which the acidification of the separator is suppressed, and a method for manufacturing the same. [Means for solving the problem]

[0008] The electrolytic capacitor of the present invention has a capacitor element in which an anode foil and a cathode foil are wound with a separator that holds a conductive polymer layer therebetween, and the separator is characterized in that it is mainly made of glass fiber having a porosity of 75 to 90(%).

[0009] In the electrolytic capacitor, the glass fibers may have a porosity of 85 to 90(%).

[0010] In the above electrolytic capacitor, the separator may hold an electrolyte, and the glass fibers may have an average fiber diameter of 0.5 to 1 (μm).

[0011] In the above electrolytic capacitor, the glass fiber may include at least one of borosilicate glass, alkali-free borosilicate glass, and high-silica glass.

[0012] In the above electrolytic capacitor, the separator may include at least one of polyester fibers, polyethylene fibers, polypropylene fibers, aramid fibers, acrylic fibers, and cellulose fibers.

[0013] In the electrolytic capacitor described above, the separator may contain at least one of polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, polyurethane, polyvinylidene fluoride, styrene butadiene rubber, and acrylic resin as a binder.

[0014] In the above electrolytic capacitor, the capacitor element may be impregnated with the electrolyte solution containing at least one of ethylene glycol, γ-butyrolactone, and sulfolane.

[0015] The method for manufacturing an electrolytic capacitor of the present invention includes the steps of winding an anode foil and a cathode foil with a separator between them to produce a capacitor element, immersing the capacitor element in a dispersion or solution of a conductive polymer, and drying the capacitor element, wherein the separator is mainly made of glass fiber having a porosity of 75 to 90%.

[0016] In the above manufacturing method, the glass fibers may have a porosity of 85 to 90(%).

[0017] The above manufacturing method may further include a step of immersing the capacitor element in an electrolyte, and the glass fibers may have an average fiber diameter of 0.5 to 1 (μm).

[0018] In the above manufacturing method, the glass fiber may contain at least one of borosilicate glass, alkali-free borosilicate glass, and high silica glass.

[0019] In the above manufacturing method, the separator may include at least one of polyester fibers, polyethylene fibers, polypropylene fibers, aramid fibers, acrylic fibers, and cellulose fibers.

[0020] In the above manufacturing method, the separator may contain at least one of polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, polyurethane, polyvinylidene fluoride, styrene butadiene rubber, and acrylic resin as a binder.

[0021] In the above manufacturing method, the capacitor element may be impregnated with the electrolyte solution containing at least one of ethylene glycol, γ-butyrolactone, and sulfolane. Effect of the Invention

[0022] According to the present invention, it is possible to suppress the acidification of the separator and improve the reliability. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a side view showing an example of an aluminum electrolytic capacitor; [Diagram 2] FIG. 2 is a perspective view showing an example of a capacitor element. [Diagram 3] 1A to 1C are diagrams illustrating an example of a manufacturing process for an aluminum electrolytic capacitor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] [Embodiment] (Aluminum electrolytic capacitor composition) Fig. 1 is a side view showing an example of an aluminum electrolytic capacitor 1. In the right half of Fig. 1 across a center line L of the aluminum electrolytic capacitor 1, a cross section of the inside is shown.

[0025] The aluminum electrolytic capacitor 1 is a conductive polymer solid electrolytic aluminum capacitor (hereinafter referred to as a solid electrolytic capacitor) or a conductive polymer hybrid aluminum electrolytic capacitor (hereinafter referred to as a hybrid electrolytic capacitor). The aluminum electrolytic capacitor 1 is mounted on an electronic circuit board and is used for coupling, decoupling, smoothing, etc.

[0026] Aluminum electrolytic capacitor 1 has a capacitor element 10, a case 11, a sealing body 12, a base plate 13, a pair of round bar portions 111, and a pair of lead portions 110. Round bar portion 111 and lead portion 110 are extraction electrodes of capacitor element 10, and lead portion 110 extends from the tip of round bar portion 111. Note that while only one round bar portion 111 is shown in Fig. 1, the other round bar portion 111 is provided at a symmetrical position across center line L.

[0027] Case 11 is made of aluminum and has a cylindrical shape with an upper opening that is closed. Case 11 covers capacitor element 10 and sealing body 12, and functions as an exterior of aluminum electrolytic capacitor 1. The shape of case 11 is not limited to a cylindrical shape, and may be a square tube shape.

[0028] Sealing body 12 is a substantially circular member made of an elastic member such as butyl rubber. Sealing body 12 is adjacent to capacitor element 10 and seals the opening at the bottom of case 11.

[0029] As described below, capacitor element 10 has a configuration in which an anode foil, a cathode foil, and a separator (electrolytic paper) are overlapped and wound. Capacitor element 10 has a pair of round bar portions 111 extending from the bottom.

[0030] The round bar portion 111 and the lead portion 110 are rod-shaped members made of aluminum or the like. The pair of round bar portions 111 are joined to the anode foil and the cathode foil by a joining means such as crimping, respectively, and function as the anode terminal and the cathode terminal of the aluminum electrolytic capacitor 1. Each round bar portion 111 is inserted into a pair of through holes 120 formed in the sealing body 12. Note that while only one of the through holes 120 is shown in FIG. 1, the other through hole 120 is provided at a symmetrical position across the center line L.

[0031] The lead portion 110 has a flat plate shape and is bent into an L shape, with its tip portion extending along the plate surface of the base plate 13. The portion of the lead portion 110 on the round bar portion 111 side is inserted into a through hole 130 of the base plate 13. The lead portion 110 is soldered to a pad on the electronic circuit board in the reflow process of the electronic circuit board.

[0032] The seat plate 13 is a plate-like member made of resin or the like, and is provided under the case 11 and the sealing body 12. The seat plate 13 supports the case 11 and the sealing body 12 with respect to the electronic circuit board to which the capacitor is to be mounted. The seat plate 13 is provided with a through hole 130 for the lead portion 110 and a groove portion 131 for accommodating the bent tip portion of the lead portion 110. The groove portion 131 extends from near the center to the outside along the bottom surface of the seat plate 13. The bottom surface of the seat plate 13 is the mounting surface of the aluminum electrolytic capacitor 1 with respect to the electronic circuit board, so that the plate-like lead portion 110 can be soldered to a pad on the electronic circuit board. Note that, although the present embodiment describes a surface-mount type aluminum electrolytic capacitor 1, the examples described below can also be applied to a lead type without the seat plate 13.

[0033] (Capacitor element configuration) Fig. 2 is a perspective view showing an example of a capacitor element 10. In Fig. 2, components common to Fig. 1 are given the same reference numerals and their description will be omitted. Capacitor element 10 has a wound body 100 in which an anode foil 101, a cathode foil 102, and a separator (electrolytic paper) 103 are wound, and a pair of extraction electrodes 19 connected to the anode foil 101 and the cathode foil 102.

[0034] A pair of extraction electrodes 19 extend below the wound body 100. Round bar portions 111 of each extraction electrode 19 are connected to anode foil 101 and cathode foil 102, respectively. Note that Fig. 2 shows the state before lead portion 110 is bent and pressed into a flat plate shape.

[0035] The anode foil 101 and the cathode foil 102 are formed of valve metals such as aluminum, tantalum, titanium, and niobium, and alloy foils and evaporated foils thereof. The surface of the anode foil 101 is etched to increase the electrode area. This ensures that the capacitor element 10 has a predetermined capacitance. Furthermore, an extremely thin oxide film is formed on the surface of the anode foil 101. This insulates the anode foil 101 from other components. The oxide film functions as a dielectric, allowing the capacitor element 10 to function as a capacitor.

[0036] On the other hand, the surface of the cathode foil 102 is etched, but no oxide film is formed on it. Note that an oxide film may be formed on the surface of the cathode foil 102, or an inorganic layer or a carbon layer may be formed on the surface of the cathode foil 102.

[0037] The separator 103 is wound while being sandwiched between the anode foil 101 and the cathode foil 102. In the case of a solid electrolytic capacitor, the separator 103 holds a conductive polymer, and in the case of a hybrid electrolytic capacitor, the separator 103 holds a conductive polymer and an electrolyte. The separator 103 is mainly made of glass fiber having a porosity of 75 to 90% and may contain other organic fibers and binders in addition to the glass fiber. As the separator 103 is mainly made of glass fiber, it is less likely to become acidic than a separator mainly made of cellulose fiber, for example.

[0038] The porosity of the glass fiber is 75 to 90(%). Here, the porosity is the ratio of the volume of the voids to the volume of the entire fiber. If the porosity is less than 75(%), the glass fiber cannot hold a sufficient amount of conductive polymer and electrolyte, and the ESR increases. On the other hand, if the porosity is more than 90(%), the glass fiber can hold a sufficient amount of conductive polymer and electrolyte, and the ESR is sufficiently reduced, but on the other hand, the strength required when winding the separator 103 cannot be maintained, and this is not appropriate.

[0039] Therefore, when the porosity of the glass fiber is 75 to 90%, the amount of conductive polymer and electrolyte retained increases, and the ESR is appropriately reduced. Preferably, when the porosity of the glass fiber is 85 to 90%, a larger amount of conductive polymer can be retained, and the ESR is further reduced. This improves the reliability of the aluminum electrolytic capacitor 1.

[0040] The average fiber diameter of the glass fibers is 0.5 to 1 (μm). If the fiber diameter exceeds 1 (μm), the evaporation rate of the electrolyte becomes excessively high, and the density of the conductive polymer eluted from the conductive polymer layer into the electrolyte increases, so that the acidification of the separator progresses. On the other hand, if the fiber diameter is less than 0.5 (μm), the retention of the conductive polymer deteriorates, which is not appropriate. Therefore, by setting the average fiber diameter of the glass fibers to 0.5 to 1 (μm), the evaporation of the electrolyte is appropriately suppressed, and acidification is suppressed.

[0041] The thickness of separator 103 is 40 μm. If the thickness of separator 103 is less than 40 μm, it will be too thin and the withstand voltage will be low.

[0042] The glass fiber includes at least one of borosilicate glass, alkali-free borosilicate glass, and high silica glass. By using these materials as the main component of the separator 103, an advantage is obtained in that the acid resistance is improved.

[0043] Separator 103 may also contain at least one of polyester fiber, polyethylene fiber, polypropylene fiber, aramid fiber, acrylic fiber, and cellulose fiber. By including these materials in separator 103, advantages such as excellent solvent resistance and improved mechanical strength such as tensile strength can be obtained.

[0044] Separator 103 may contain at least one of polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, polyurethane, polyvinylidene fluoride, styrene butadiene rubber, and acrylic resin as a binder. By including these binders in separator 103, advantages such as excellent solvent resistance and improved mechanical strength such as tensile strength can be obtained.

[0045] Furthermore, when the aluminum electrolytic capacitor 1 is a solid electrolytic capacitor, the separator 103 is impregnated with an electrolytic solution. The solvent of the electrolytic solution may contain at least one of ethylene glycol, γ-butyrolactone, and sulfolane. By impregnating the separator 103 with an electrolytic solution containing these solvents, an advantage is obtained in that the transpiration is lower than in the past.

[0046] (Electrolytic capacitor manufacturing process) 3 is a diagram showing an example of a manufacturing process for the aluminum electrolytic capacitor 1. The manufacturing process for the aluminum electrolytic capacitor 1 is an example of a method for manufacturing an electrolytic capacitor. Note that, although a manufacturing process for a hybrid electrolytic capacitor is given in this example, the following step St6 is omitted in the method for manufacturing a solid electrolytic capacitor.

[0047] First, anode foil 101, cathode foil 102, and separator 103 are prepared (step St1). The surface of anode foil 101 is etched, and an oxide film is formed as a dielectric layer. Separator 103 has a porosity of 75 to 90% and is mainly made of glass fiber. Here, the porosity is preferably 85 to 90%. The average fiber diameter of the glass fiber is preferably 0.5 to 1 μm, which is favorable from the viewpoint of the evaporation rate of the electrolyte and the impregnation of the conductive polymer. Separator 103 has a thickness of 40 μm.

[0048] Next, the separator 103, the anode foil 101, the cathode foil 102, and the separator 103 are stacked in this order, wound, and the outer surfaces are fixed with a winding tape to produce the wound body 100 (step St2). During the winding, the extraction electrodes 19 are connected to appropriate positions of the anode foil 101 and the cathode foil 102, respectively. The connection means may be, but is not limited to, crimping.

[0049] Next, in a reduced pressure atmosphere, the wound body 100 is immersed in a conductive polymer dispersion liquid containing water and an organic solvent for 20 minutes, and then the wound body 100 is pulled up from the conductive polymer dispersion liquid (step St3). In this manner, the wound body 100 can be impregnated with the conductive polymer. Note that in this step, a conductive polymer solution may be used instead of the conductive polymer dispersion liquid.

[0050] Next, the wound body 100 is placed in a drying oven at, for example, 150 degrees and dried for 60 minutes (step St4), which causes the conductive polymers in the separator 103 to bond together to generate a conductive polymer layer, thereby forming a conductive path.

[0051] Next, in a reduced pressure atmosphere, a predetermined amount of electrolyte is impregnated into the wound body 100 (step St5). The electrolyte may be a conductive polymer dispersion liquid mixed with a solute. In other words, the conductive polymer dispersion liquid can be used as the electrolyte. In this case, the impregnation of the electrolyte is performed simultaneously with the impregnation of the conductive polymer.

[0052] Next, wound body 100 is housed in case 11 and sealed with sealing body 12 (step St6). At this time, extraction electrode 19 extending from wound body 100 is inserted into through hole 120 of sealing body 12. Thereafter, an aging treatment may be performed while applying a rated voltage to capacitor element 10. In this manner, the manufacturing process for aluminum electrolytic capacitor 1 is performed. EXAMPLES

[0053] Next, an example of the aluminum electrolytic capacitor 1 will be described. Samples No. 1 to 8 of the aluminum electrolytic capacitor 1 were produced according to the above-mentioned manufacturing method. For comparison, samples No. 9 and No. 10 of the aluminum electrolytic capacitor were produced in which the main part of the separator 103 was made of special rayon fiber (a finely divided cellulose fiber) and cellulose fiber instead of glass fiber. The rated voltage and rated capacitance of samples No. 1 to No. 10 were 63 (V) and 56 (μF), respectively. The diameter of the case 11 was 10 (mm), and the height of the case 11 was 10 (mm). A specific manufacturing method of the aluminum electrolytic capacitor 1 will be described below.

[0054] (Making of the roll) The anode lead electrode was connected to the anode foil, which had been etched and had an oxide film formed on it. The cathode lead electrode was connected to the cathode foil, which had a conductor layer on its end surface and had been pretreated to improve wettability. The separator, cathode foil, separator, and anode foil were then stacked in that order, and the lead electrodes were rolled up while being rolled up, and the outer surface was fixed with a stopper tape to create a wound body. The thickness of the separator, the fiber diameter of the separator's main fiber, and the porosity were varied for each sample.

[0055] The prepared wound body was immersed in an aqueous solution of ammonium phosphate, and a chemical conversion treatment was again performed at 85°C while a predetermined voltage was applied to the anode foil, thereby forming a dielectric layer mainly on the end surfaces of the anode foil.

[0056] (Impregnation of conductive polymers) The wound body was immersed in a conductive polymer dispersion liquid contained in a specified container in a reduced pressure atmosphere (-93 kPa), and then the wound body was pulled out of the dispersion liquid. Next, the wound body impregnated with the conductive polymer was dried in a drying oven at 150°C for 60 minutes to bond the conductive polymers of each layer together and form a conductive path. This produced a capacitor element that functions as a solid electrolytic capacitor.

[0057] (Electrolyte Impregnation) Furthermore, the above capacitor element was impregnated with a predetermined amount of electrolyte (ESE2 manufactured by Teika Corporation) in a reduced pressure atmosphere, thereby producing a capacitor element that functions as a hybrid aluminum electrolytic capacitor.

[0058] (Sealing of capacitor element) The capacitor element impregnated with the electrolyte was sealed to complete the electrolytic capacitor. After that, an aging treatment was performed for a predetermined time at a predetermined temperature while applying a rated voltage.

[0059] (evaluation) Samples No. 1 to 10 were evaluated as solid electrolytic capacitors and hybrid electrolytic capacitors. Using a four-terminal LCR meter, the ESR (mΩ) of the solid electrolytic capacitors and hybrid electrolytic capacitors was measured at a frequency of 100 kHz in an environment of 20°C. The amount of polymer (conductive polymer) retained (g) was also measured to evaluate the solid electrolytic capacitors, and the rate of evaporation of the electrolyte (g / h) at 150°C was measured to evaluate the hybrid electrolytic capacitors. Table 1 shows the measurement results for the solid electrolytic capacitors, and Table 2 shows the measurement results for the hybrid electrolytic capacitors.

[0060] [Table 1]

[0061] Table 1 shows the evaluation results of samples No. 1 to 10 as solid electrolytic capacitors. The separators of samples No. 1 to 8 were mainly made of glass fiber, while the separators of samples No. 9 and 10 were mainly made of special rayon fiber and cellulose fiber, respectively. The ratio of the weight of the main fiber to the total weight of the separator (see weight ratio in Table 1) was 100(%) for samples No. 9 and 10, 65(%) for sample No. 4, and 75(%) for the others.

[0062] The fiber diameter is the average value of the diameters of the main fibers of the separator, and was measured by measuring the separator in plan view at 5000 times magnification using a scanning electron microscope (SEM). The fiber diameters of samples No. 1 to 4, 6, and 8 were 0.5 (μm), the fiber diameter of sample No. 5 was 1.2 (μm), and the fiber diameter of sample No. 7 was 1.0 (μm). The fiber diameter of sample No. 9 was 2.0 (μm), and the fiber diameter of sample No. 10 was 5.0 (μm). The thickness of the separator of sample No. 6 was 30 (μm), and the thickness of the separators of the other samples was 40 (μm).

[0063] The porosity of the separator was varied for each sample. For samples Nos. 1 to 4 and 8, the higher the separator porosity, the higher the polymer retention amount and the lower the ESR tended to be. However, samples Nos. 5 and 7 had a lower porosity than sample No. 4, but the fiber diameter was larger, improving the polymer impregnation, resulting in a higher polymer retention amount and a lower ESR. Sample No. 6 also had a lower porosity than sample No. 4, but was thinner and had a shorter conductive path, resulting in a lower ESR.

[0064] The ESR of Samples No. 1 to No. 8 of the Example was judged as OK / NG based on the ESR of Samples No. 9 and 10 of the Comparative Examples (see the judgment results in the table). Samples No. 1 to No. 7 were judged as OK because the ESR was lower than that of Samples No. 9 and 10. Sample No. 8 was judged as NG because it had a high ESR, even though it had the same thickness as Sample No. 9 and a higher porosity than Sample No. 9. Furthermore, Sample No. 1, which had a porosity of 90%, and Sample No. 2, which had a porosity of 85%, retained a large amount of polymer, and therefore the ESR was further reduced appropriately.

[0065] Therefore, the ESR of Samples Nos. 1 to 7, which had a porosity of 75 to 90%, was suitably reduced. Furthermore, the ESR of Samples Nos. 1 and 2, which had a porosity of 85 to 90%, was suitably reduced.

[0066] Also, the thickness of sample No. 6 was thinner than the other samples No. 1 to 5, 7, and 8. Therefore, the withstand voltage of sample No. 6 was lower than that of comparative sample No. 9. On the other hand, the withstand voltages of samples No. 1 to 5, 7, and 8 were equal to or higher than that of comparative sample No. 9. Therefore, it is preferable that the thickness of the separator is 40 (μm).

[0067] [Table 2]

[0068] Table 2 shows the evaluation results of the hybrid electrolytic capacitors of Samples No. 1 to 10. The contents of Table 2 are the same except for the amount of electrolyte retained, ESR, evaporation rate of the electrolyte, and the evaluation results.

[0069] As in the case of solid electrolytic capacitors, for samples Nos. 1 to 4 and 8, the higher the porosity of the separator, the greater the amount of electrolyte retained and the lower the ESR. However, samples Nos. 5 and 7 had lower porosity than sample No. 4, but had a larger fiber diameter and improved polymer impregnation, resulting in a greater amount of electrolyte retained and a lower ESR. Sample No. 6 also had a lower porosity than sample No. 4, but was thinner and had a shorter conductive path, resulting in a lower ESR.

[0070] The ESR of Samples Nos. 1 to 8 of the embodiment was judged as OK / NG based on the ESR of Samples Nos. 9 and 10 as comparative examples (see the judgment results in the table). Samples Nos. 1 to 7 were judged as OK because they had lower ESR than Samples Nos. 9 and 10. Sample No. 8 had the same thickness as Sample No. 9 and a higher porosity than Sample No. 9, but had a higher ESR and was therefore judged as NG.

[0071] Therefore, the ESR of Samples No. 1 to 7, which had a porosity of 75 to 90%, was suitably reduced. Furthermore, Samples No. 1 and 2, which had a porosity of 85 to 90%, had a larger amount of polymer retained, and therefore the ESR was further suitably reduced.

[0072] The evaporation rate of the electrolyte increases with increasing fiber diameter. This is because the contact area with the electrolyte decreases as the fiber diameter increases, decreasing the electrolyte retention. As the electrolyte evaporates, the acidity increases due to the density of the conductive polymer eluted from the conductive polymer layer into the electrolyte, and the separator becomes more acidic.

[0073] When the evaporation rates of the electrolyte of the comparative samples No. 9 and No. 10 are taken as a standard, the evaporation rate of the electrolyte of the sample No. 5 having the largest fiber diameter among the samples No. 1 to No. 8 is higher than that of the samples No. 9 and No. 10. This is because the fiber diameter of the sample No. 5 is larger than that of the other samples No. 1 to No. 4, No. 6 to No. 8. On the other hand, the evaporation rates of the electrolyte of the other samples No. 1 to No. 4, No. 6 to No. 8 are lower than that of the samples No. 9 and No. 10. Therefore, by setting the average fiber diameter of the glass fiber to 0.6 to 1 (μm), the evaporation of the electrolyte is appropriately suppressed and acidification is suppressed. Here, when the average fiber diameter is less than 0.5 (μm), the impregnation of the polymer decreases, and therefore it is not appropriate.

[0074] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0075] 1. Aluminum electrolytic capacitor 10 Capacitor element 11 Cases 12 Sealing body 13 Seat board 19 Extraction electrode 100 rolls 101 Anode foil 102 Cathode foil 103 Separator

Claims

1. a capacitor element in which an anode foil and a cathode foil are wound with a separator that holds a conductive polymer layer therebetween; The separator is mainly made of glass fibers having a porosity of 75 to 90%.

2. 2. The electrolytic capacitor according to claim 1, wherein the glass fibers have a porosity of 85 to 90%.

3. The separator holds an electrolyte, 3. The electrolytic capacitor according to claim 1, wherein the glass fibers have an average fiber diameter of 0.5 to 1 μm.

4. 3. The electrolytic capacitor according to claim 1, wherein the glass fibers contain at least one of borosilicate glass, alkali-free borosilicate glass, and high-silica glass.

5. 3. The electrolytic capacitor according to claim 1, wherein the separator includes at least one of polyester fibers, polyethylene fibers, polypropylene fibers, aramid fibers, acrylic fibers, and cellulose fibers.

6. 3. The electrolytic capacitor according to claim 1, wherein the separator contains at least one of polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, polyurethane, polyvinylidene fluoride, styrene butadiene rubber, and acrylic resin as a binder.

7. 4. The electrolytic capacitor according to claim 3, wherein the capacitor element is impregnated with the electrolyte solution containing at least one of ethylene glycol, γ-butyrolactone, and sulfolane.

8. winding the anode foil and the cathode foil with a separator to form a capacitor element; immersing the capacitor element in a dispersion or solution of a conductive polymer; and drying the capacitor element. The method for producing an electrolytic capacitor is characterized in that the separator is mainly made of glass fibers having a porosity of 75 to 90(%).

9. 9. The method for producing an electrolytic capacitor according to claim 8, wherein the glass fibers have a porosity of 85 to 90%.

10. The method further comprises the step of immersing the capacitor element in an electrolyte, 10. The method for manufacturing an electrolytic capacitor according to claim 8, wherein the average fiber diameter of the glass fibers is 0.5 to 1 (μm).

11. 10. The method for producing an electrolytic capacitor according to claim 8, wherein the glass fibers contain at least one of borosilicate glass, non-alkali borosilicate glass, and high silica glass.

12. 10. The method for manufacturing an electrolytic capacitor according to claim 8, wherein the separator includes at least one of polyester fibers, polyethylene fibers, polypropylene fibers, aramid fibers, acrylic fibers, and cellulose fibers.

13. 10. The method for manufacturing an electrolytic capacitor according to claim 8, wherein the separator contains at least one of polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, polyurethane, polyvinylidene fluoride, styrene butadiene rubber, and acrylic resin as a binder.

14. 11. The method for producing an electrolytic capacitor according to claim 10, wherein the capacitor element is impregnated with the electrolyte solution containing at least one of ethylene glycol, γ-butyrolactone, and sulfolane.

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