JP6191860B2 - Electrolytic capacitor manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a wound type electrolytic capacitor.

  The electrolytic capacitor includes a capacitor element, a bottomed cylindrical outer case in which the capacitor element is accommodated, and a sealing member that seals an opening of the outer case (see, for example, Patent Document 1). The capacitor element has a wound body, and the wound body includes an anode foil, a cathode foil, and a separator. A dielectric film is formed on the surface of the anode foil. In the wound body, the anode foil and the cathode foil are wound in a state where the cathode foil is superimposed on the anode foil. The separator is superimposed on the anode foil and the cathode foil so as to be interposed between the anode foil and the cathode foil in the wound body. The separator is impregnated with an electrolyte.

  Conventionally, it has been proposed to use a synthetic fiber as a constituent material of a separator (for example, Patent Document 2). Such synthetic fibers include acrylic and vinylon.

Japanese Utility Model Publication No. 61-75124 JP 2006-344742 A

  However, when a synthetic fiber such as acrylic or vinylon is used as a constituent material of the separator, when the wound body is heat-treated in the manufacturing process of the electrolytic capacitor, the synthetic fiber is likely to undergo a state change such as crimping. Such a change in the state of the synthetic fiber causes the separator to expand in the thickness direction. For this reason, the wound body expands, and this may cause deformation of the wound body or breakage of the winding stop tape wound around the outermost peripheral surface of the wound body. Further, the change in the state of the synthetic fiber causes the separator to contract in the length direction and the width direction. For this reason, there is a portion where no separator is interposed between the anode foil and the cathode foil, and the anode foil and the cathode foil may be electrically short-circuited at the portion.

  Therefore, it is conceivable to use a synthetic fiber having high heat resistance such as aramid as a constituent material of the separator. However, such a synthetic fiber is an expensive material and increases the manufacturing cost of the electrolytic capacitor.

  In addition, for example, when reflow soldering is performed in order to mount the electrolytic capacitor on the substrate, there is a possibility that the gas remaining in the synthetic fiber in the separator may be released due to heat applied to the electrolytic capacitor, There was a risk that gas was generated due to partial decomposition. Such gas generation is not preferable because it causes an increase in the internal pressure of the electrolytic capacitor.

  Therefore, an object of the present invention is to suppress a defect such as deformation of the wound body or electrical short circuit that may occur with a change in the state of the synthetic fiber in the method of manufacturing an electrolytic capacitor in which the synthetic fiber is included in the separator, Moreover, it is to realize the production of an electrolytic capacitor in which gas due to the synthetic fiber is hardly generated.

  An electrolytic capacitor manufacturing method according to the present invention is a manufacturing method in which a wound body is formed by winding a separator containing a synthetic fiber and an electrode member, and then the wound body is impregnated with an electrolyte, and the separator is formed. It has a process, a first heat treatment process, a winding process, and a second heat treatment process. In the separator forming step, paper is made from the synthetic fiber. Before or after the separator formation step, in the first heat treatment step, the synthetic fiber is heat-treated at a first temperature set to be equal to or higher than the softening point of the synthetic fiber. After the separator formation step and the first heat treatment step, the winding body is formed by winding the separator and the electrode member in the winding step. After the winding step, in the second heat treatment step, the wound body is heat-treated at a second temperature set to be equal to or lower than the first temperature. In addition, about the synthetic | combination material of a fiber, the temperature measured based on JIS-K7206 (Vicat softening temperature test method of a thermoplastic plastic) in the bulk state before fiberizing was defined as the softening point of a synthetic fiber.

  In the said manufacturing method, it is preferable that 2nd temperature is set more than the softening point of a synthetic fiber. The synthetic fiber preferably contains one or more fibers selected from the group consisting of acrylic, vinylon, nylon, polyester, polyethylene terephthalate, and polyethylene naphthalate.

  According to the method for manufacturing an electrolytic capacitor according to the present invention, it is possible to suppress an inconvenience that may occur with a change in the state of the synthetic fiber and to manufacture an electrolytic capacitor that hardly generates a gas due to the synthetic fiber.

It is sectional drawing which showed an example of the electrolytic capacitor produced with the manufacturing method of this invention. It is the perspective view which decomposed | disassembled and showed the capacitor element with which an electrolytic capacitor is provided. It is the flowchart which showed the manufacturing method of the electrolytic capacitor. It is the flowchart which showed the modification of the manufacturing method of an electrolytic capacitor.

  FIG. 1 is a cross-sectional view showing an example of an electrolytic capacitor produced by the production method of the present invention. As shown in FIG. 1, the electrolytic capacitor includes a capacitor body 40 and a seat plate 50 on which the capacitor body 40 is mounted. The capacitor main body 40 includes a capacitor element 41, a bottomed cylindrical outer case 42 in which the capacitor element 41 is accommodated, and a sealing member 43 that is fitted into the opening 421 of the outer case 42. .

  FIG. 2 is a perspective view showing a part of the capacitor element 41 in an exploded manner. As shown in FIG. 2, the capacitor element 41 includes a wound body 1, an anode lead tab terminal 2, and a cathode lead tab terminal 3. The wound body 1 includes an anode foil 11, a cathode foil 12, and two separators 13 and 14. Here, the anode foil 11 and the cathode foil 12 are each formed from a valve action metal such as aluminum, tantalum, or niobium. A dielectric coating (not shown) is formed on the surface of the anode foil 11. The separators 13 and 14 include, for example, one or more synthetic fibers selected from the group consisting of acrylic, vinylon, nylon, polyester, polyethylene terephthalate, and polyethylene naphthalate.

  In the wound body 1, the anode foil 11 and the cathode foil 12 are wound in a state where the cathode foil 12 is superimposed on the anode foil 11. The separators 13 and 14 are overlaid on the anode foil 11 and the cathode foil 12 respectively so as to be interposed between the anode foil 11 and the cathode foil 12 in the wound body 1. The separators 13 and 14 are impregnated with at least one of an electrolyte solution and a solid electrolyte. The wound body 1 may be formed by winding various forms of anode members and cathode members that are not limited to foil.

  As shown in FIG. 2, the anode lead tab terminal 2 is attached to the anode foil 11 and is electrically connected to the anode foil 11. The cathode lead tab terminal 3 is attached to the cathode foil 12 and electrically connected to the cathode foil 12. As shown in FIG. 1, the anode lead tab terminal 2 and the cathode lead tab terminal 3 are drawn out from the lower end surface 1 a of the wound body 1. The number of anode lead tab terminals 2 connected to the anode foil 11 is not limited to one and may be a plurality. Further, the number of cathode lead tab terminals 3 connected to the cathode foil 12 is not limited to one and may be plural.

  The anode lead tab terminal 2 and the cathode lead tab terminal 3 penetrate the sealing member 43. Thereby, the capacitor element 41 is fixed to the sealing member 43, and the lead portion 21 of the anode lead tab terminal 2 and the lead portion 31 of the cathode lead tab terminal 3 are drawn out of the outer case 42. Each of the lead portions 21 and 31 penetrates the seat plate 50 and is bent so that the tip portion is along the lower surface 50 a of the seat plate 50. In this way, the external terminals of the electrolytic capacitor are formed by the portions of the lead portions 21 and 31 that are present on the lower surface 50a of the seat plate 50.

  The outer case 42 is made of a metal material such as aluminum. The opening 421 of the outer case 42 is formed with a throttle portion 422 for fixing the sealing member 43 to the outer case 42 by performing a horizontal drawing process on the opening 421. In the present embodiment, the opening end of the outer case 42 is further curled. The exterior case 42 is not limited to a metal material, and may be formed from various materials including an electrical insulating material.

  The sealing member 43 is formed from an elastic material such as rubber. The throttle unit 422 compresses the sealing member 43 from the periphery to the inside. As a result, the sealing member 43 is elastically deformed, and its side peripheral surface 43 a is in close contact with the inner peripheral surface 42 a of the exterior case 42. In this way, the opening 421 of the exterior case 42 is sealed by the sealing member 43. Note that the opening 421 of the outer case 42 may be sealed with the resin material by filling the opening 421 with a resin material instead of the insertion of the sealing member 43.

  Next, as an embodiment of the present invention, a method for manufacturing the electrolytic capacitor will be specifically described. FIG. 3 is a flowchart showing the manufacturing method of the present embodiment. In the present embodiment, the first heat treatment step, the separator formation step, the winding step, the re-chemical conversion treatment step, the second heat treatment step, the electrolyte impregnation step, and the sealing step are performed in this order. .

  In the first heat treatment step, first, synthetic fibers that are constituent materials of the separators 13 and 14 are prepared. Specifically, one or more synthetic fibers are selected from the group consisting of acrylic, vinylon, nylon, polyester, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). The softening points of these synthetic fibers are as follows. That is, acrylic is 190 to 240 ° C, vinylon is 220 to 230 ° C, nylon is 230 to 235 ° C, polyester is 238 to 240 ° C, PET is about 260 ° C, and PEN is about 275 ° C. It is difficult to measure the softening point of the synthetic fiber in that state (fiber state) after the fiber synthetic material is made into a fiber. Therefore, regarding the synthetic material of the fiber, the temperature measured in accordance with JIS-K7206 (a method for testing the Vicat softening temperature of thermoplastics) in the bulk state before fiberization was defined as the softening point of the synthetic fiber.

  Next, heat treatment is performed on the prepared synthetic fiber. Specifically, when only one type of synthetic fiber is selected when preparing the synthetic fiber, the prepared synthetic fiber is heat-treated at a first temperature set to be equal to or higher than the softening point of the synthetic fiber. On the other hand, when two or more types of synthetic fibers are selected when preparing the synthetic fibers, the first temperature is set to be equal to or higher than the lowest softening point among the softening points of the prepared synthetic fibers. More preferably, 1st temperature is set more than the softening point with the highest temperature among the softening points of the prepared synthetic fiber. Then, the prepared synthetic fiber is heat-treated at the first temperature. In addition, it is preferable that 1st temperature is a temperature 10 degree | times or more higher than the softening point used as a reference | standard. However, the first temperature is set to a temperature at which the synthetic fiber does not melt or decompose. Moreover, it is preferable that the heat processing time of a synthetic fiber is 1 hour or less.

  In the separator forming step, the separators 13 and 14 are made using a synthetic fiber after heat treatment. At this time, natural fibers such as cellulose and pulp may be mixed (mixed) with the synthetic fibers. For the formation of the separators 13 and 14, a binder such as polyvinyl alcohol, polyester, or polyethylene glycol may be used. In addition, it is preferable that the thickness of the separators 13 and 14 is 10-100 micrometers, respectively.

  In the winding process, the wound body 1 is formed by winding the anode foil 11, the cathode foil 12, and the separators 13 and 14 around a winding core (not shown) (see FIG. 2). Then, in order to prevent the winding body 1 from being deformed, a winding tape (not shown) is wound around the outermost peripheral surface of the winding body 1. The anode foil 11 is formed by cutting a metal foil having a dielectric coating on the surface into a predetermined shape. Therefore, a part of the metal constituting the anode foil 11 is exposed on the cut surface. Further, the dielectric coating is easily damaged by the stress applied when the anode foil 11 is wound.

  In the re-chemical conversion treatment step, the wound body 1 is subjected to a re-chemical conversion treatment. Specifically, the wound body 1 is immersed in a chemical conversion solution such as an aqueous solution of ammonium adipate, and a voltage is applied between the anode lead tab terminal 2 and the chemical conversion solution in this state. Thereby, a dielectric film is formed on the exposed surface (cut surface) of the anode foil 11, and the damaged portion of the dielectric film is repaired. As a result, the entire surface of the anode foil 11 is covered with the dielectric film.

  In the second heat treatment step, the wound body 1 is subjected to heat treatment for carbonization treatment of the separators 13 and 14, annealing treatment after the re-chemical conversion treatment, and further decomposition treatment of the binder contained in the separators 13 and 14. It is a process. Specifically, the wound body 1 is heat-treated at a second temperature set to be equal to or lower than the first temperature. Here, when the separators 13 and 14 include only one type of synthetic fiber, the second temperature is preferably set to be equal to or higher than the softening point of the synthetic fiber. On the other hand, when the separators 13 and 14 include two or more kinds of synthetic fibers, the second temperature is preferably set to a softening point that is the lowest among the softening points of the synthetic fibers.

  In the electrolyte impregnation step, the separators 13 and 14 are impregnated with at least one of an electrolyte solution and a solid electrolyte. Thereby, the capacitor element 41 is completed.

  In the sealing step, the capacitor element 41 is inserted into the outer case 42 and the opening 421 of the outer case 42 is sealed with the sealing member 43. In addition, you may seal the opening part 421 of the exterior case 42 by filling this with the resin material. Thereby, the capacitor body 40 is completed. Thereafter, the electrolytic capacitor is completed by mounting the capacitor body 40 on the seat plate 50.

  In the manufacturing method of the present embodiment, heat treatment is performed on the synthetic fibers in the first heat treatment step before the separators 13 and 14 are formed. At this time, since the first temperature, which is the heat treatment temperature, is equal to or higher than the softening point of the synthetic fiber, the state of the synthetic fiber changes due to softening. And even if the separators 13 and 14 formed from such synthetic fibers are subjected to heat treatment in the subsequent process, the separators 13 and 14 hardly expand or contract as long as the temperature is equal to or lower than the first temperature. Therefore, even when the wound body 1 is heat-treated in the second heat treatment step, the heat treatment temperature (second temperature) at that time is equal to or lower than the first temperature, so that the separators 13 and 14 hardly expand or contract. Therefore, according to the manufacturing method of the present embodiment, problems such as deformation of the wound body 1 and breakage of the winding tape, which may occur as the separator 13 or 14 expands, and further, as the separator 13 or 14 contracts. Problems such as electrical short circuits that can occur are suppressed.

  In addition, according to the manufacturing method of the present embodiment, by performing the first heat treatment step in advance, the gas remaining in the synthetic fibers in the separators 13 and 14 is released, and the synthetic fibers in the separators 13 and 14 are also released. A part of is disassembled. Therefore, even when the produced electrolytic capacitor is heated, the separator 13 or 14 hardly generates gas due to the synthetic fiber. In addition, the case where an electrolytic capacitor is mounted in a board | substrate by reflow soldering is mentioned as a scene where an electrolytic capacitor is heated. Therefore, according to the manufacturing method of the present embodiment, an increase in the internal pressure of the electrolytic capacitor can be prevented.

  Furthermore, acrylic, vinylon, nylon, polyester, polyethylene terephthalate, and polyethylene naphthalate are inexpensive and have a low softening point as described above. Therefore, the manufacturing method of this embodiment is suitable for the electrolytic capacitor in which these synthetic fibers are used as the constituent material of the separators 13 and 14.

  FIG. 4 is a flowchart showing a modification of the manufacturing method. In this modification, the first heat treatment step is performed after the separator formation step. In addition, about the process after the winding process performed after a 1st heat treatment process, since it is the same as that of the said embodiment, description is abbreviate | omitted.

  In the separator forming step, first, synthetic fibers that are constituent materials of the separators 13 and 14 are prepared. Specifically, at least one synthetic fiber is selected from the group consisting of acrylic, vinylon, nylon, polyester, polyethylene terephthalate, and polyethylene naphthalate. Next, the separators 13 and 14 are paper-made using the prepared synthetic fiber. At this time, natural fibers such as cellulose and pulp may be mixed (mixed) with the synthetic fibers. For the formation of the separators 13 and 14, a binder such as polyvinyl alcohol, polyester, or polyethylene glycol may be used.

  In the first heat treatment step, the synthetic fibers contained in the separators 13 and 14 are heat-treated by heat-treating the separators 13 and 14. Specifically, when the separator 13 is formed using only one type of synthetic fiber, the separator 13 is heat-treated at a first temperature set to be equal to or higher than the softening point of the synthetic fiber included therein. On the other hand, when the separator 13 is formed using two or more kinds of synthetic fibers, the first temperature is set to be equal to or higher than the lowest softening point among the softening points of the synthetic fibers included in the separator 13. More preferably, the first temperature is set to be equal to or higher than the highest softening point among the softening points of the synthetic fibers contained in the separator 13. Then, the separator 13 is heat-treated at the first temperature. The separator 14 is similarly heat-treated. In addition, it is preferable that 1st temperature is a temperature 10 degree | times or more higher than the softening point used as a reference | standard. However, the first temperature is set to a temperature at which the synthetic fiber does not melt or decompose. Moreover, it is preferable that the heat processing time of a synthetic fiber is 1 hour or less. Furthermore, the thickness of the separators 13 and 14 after the heat treatment is preferably 10 to 100 μm.

  In the manufacturing method of the modified example, after the separators 13 and 14 are formed and before the winding body 1 is formed, the separators 13 and 14 are subjected to heat treatment in the first heat treatment step. At this time, since the first temperature, which is the heat treatment temperature, is equal to or higher than the softening point of the synthetic fiber, the separators 13 and 14 expand or contract as the synthetic fiber softens. And even if the separators 13 and 14 are subjected to a heat treatment in the subsequent process, the separators 13 and 14 change to a state where they hardly expand or contract if the temperature is not higher than the first temperature. Therefore, even when the wound body 1 is heat-treated in the second heat treatment step, the heat treatment temperature (second temperature) at that time is equal to or lower than the first temperature, so that the separators 13 and 14 hardly expand or contract. Therefore, according to the manufacturing method of the modified example, problems such as deformation of the wound body 1 and breakage of the winding tape that may occur with expansion of the separator 13 or 14, and further, contraction of the separator 13 or 14 occur. Problems such as an electrical short circuit obtained are suppressed.

  Further, according to the manufacturing method of the modified example, by performing the first heat treatment step in advance, the gas remaining in the synthetic fibers in the separators 13 and 14 is released, and the synthetic fibers in the separators 13 and 14 A part is decomposed. Therefore, even when the produced electrolytic capacitor is heated, the separator 13 or 14 hardly generates gas due to the synthetic fiber. In addition, the case where an electrolytic capacitor is mounted in a board | substrate by reflow soldering is mentioned as a scene where an electrolytic capacitor is heated. Therefore, according to the manufacturing method of the modified example, an increase in the internal pressure of the electrolytic capacitor can be prevented.

  In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, the embodiment and the modification can be applied not only to the above-described synthetic fiber but also to a method for manufacturing an electrolytic capacitor in which various synthetic fibers having a softening point are used as constituent materials of the separator. Moreover, the said embodiment and modification are applicable also to the manufacturing method of the electrolytic capacitor which does not have a cathode foil.

DESCRIPTION OF SYMBOLS 1 Winding body 1a Lower end surface 2 Anode lead tab terminal 3 Cathode lead tab terminal 11 Anode foil (electrode member)
12 Cathode foil (electrode member)
13, 14 Separator 21, 31 Lead portion 40 Capacitor body 41 Capacitor element 42 Exterior case 42a Inner peripheral surface 43 Sealing member 43a Side peripheral surface 50 Seat plate 50a Lower surface 421 Opening portion 422 Restriction portion

Claims (3)

A method for producing an electrolytic capacitor, comprising forming a wound body by winding a separator containing a synthetic fiber and an electrode member, and impregnating the wound body with an electrolyte,
Heat treating the synthetic fiber at a first temperature set above the softening point of the synthetic fiber;
After the step of heat-treating at the first temperature, a step of papermaking the separator from the synthetic fiber;
After enough engineering for papermaking the separator, by winding the separator and the electrode member, and forming the wound body,
And a step of heat-treating the wound body at a second temperature set to be equal to or lower than the first temperature after the step of forming the wound body.   The method for manufacturing an electrolytic capacitor according to claim 1, wherein the second temperature is set to be equal to or higher than the softening point. The method for producing an electrolytic capacitor according to claim 1 or 2, wherein the synthetic fiber includes one or more fibers selected from the group consisting of acrylic, vinylon, nylon, polyester, polyethylene terephthalate, and polyethylene naphthalate. .

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