JP4999610B2 - Electrolytic capacitor and manufacturing method thereof - Google Patents

Description

The present invention relates to a case-containing capacitor used in various electronic devices and industrial devices and a manufacturing method thereof , in particular, a sealing plate in which a rubber plate is attached to a substrate, among sealing plates that close the case upper portion of an electrolytic capacitor, and a sealing plate It relates to the manufacturing method .

Conventionally, an aluminum electrolytic capacitor has an aluminum foil as an anode and a cathode, and is laminated or wound through a separator to impregnate an electrolytic solution composed of an organic solvent such as ethylene glycol and an electrolyte as a capacitor element, and a sealing plate is attached to the case. It was stored in. In order to extract the electrode from the capacitor element, one end of a lead lead tab made of aluminum foil is connected to the anode and the cathode, and the other end of the lead lead tab is connected to an external terminal provided on the sealing plate. It was.
In addition, in the case of a sealing plate of paper phenolic insulating plate and rubber plate that are widely distributed in the market, for example, the external terminal has a rivet and a metal plate terminal attached to it, and a flat washer is provided from the insulating plate side. In order to fix to the insertion sealing plate and to connect and fix the drawer lead tab, a hole is made in the end of the drawer lead tab, it is inserted into the cylindrical part of the rivet, then a flat washer is inserted, and riveting is generally performed by caulking. Is.

  In addition, the insulation plate of the sealing plate of the type in which a paper phenol insulation plate and a rubber plate are bonded together is impregnated with a paper base material in which phenol resin before crosslinking is dissolved in alcohol etc. However, when the insulating plate of this capacitor sealing plate comes into contact with the electrolyte or its vapor, its surface is eroded and impurities such as chlorine in the paper substrate or phenol resin flow out. Thus, impurities such as chlorine adhering to the vaporized electrolyte solution have a drawback that corrodes aluminum materials such as a rivet portion inside the capacitor and a lead lead tab.

For this purpose, conventionally, an ionic substance blocking resin film such as ethylene, propylene, a copolymer of ethylene and propylene, or a polyphenylene sulfide film is laminated and integrated on the inner surface of the insulating plate of the sealing plate (patent) Document 1), rubber moldings such as ethylene propylene rubber and butyl rubber moldings are provided on the inner surface and side surface of the insulating plate of the sealing plate (Patent Document 2), such as chlorine in the insulating plate of the sealing plate. The outflow of impurities was prevented.
JP-A-9-283385 Japanese Patent Laid-Open No. 5-200896

An electrolytic capacitor with a sealing plate using a rubber-coated paper phenol insulating plate is laminated and integrated with an ionic substance-blocking resin film on the inner surface of the insulating plate of the sealing plate. In the case of providing a through hole for a terminal, impurities such as chlorine may flow out from the side surface of the sealing plate and the inner surface of the through hole for the external terminal because the processed surface of paper phenol remains exposed. is there.
In addition, when the rubber molded body is provided on the inner surface and the side surface of the insulating plate of the sealing plate, especially when used in a high temperature state, the plasticizer or anti-aging agent contained in the rubber molded body easily flows out into the electrolyte solution, There is a difficulty in high temperature solvent resistance. The present invention is intended to solve these points.

In order to solve the above-mentioned problems, the present invention provides an electrolytic plate having a sealing plate using a rubber- coated paper phenol insulating plate of a paper base, a through hole provided in the sealing plate, and an external terminal penetrating the through hole. In the capacitor, a coating film of a fluororesin of tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer or hexafluoropropylene-vinylidene fluoride copolymer is provided at least on the side surface of the sealing plate and the inner surface of the through hole. An electrolytic capacitor is provided.
Further, in a method of manufacturing an electrolytic capacitor having a sealing plate using a rubber-coated paper phenol insulating plate of a paper base, a through hole provided in the sealing plate, and an external terminal penetrating the through hole, tetrafluoroethylene- It is characterized in that a fluororesin film is provided by applying a solution of hexafluoropropylene-vinylidene fluoride copolymer or hexafluoropropylene-vinylidene fluoride solution on at least the side surface of the sealing plate and the inner surface of the through hole. An electrolytic capacitor manufacturing method is provided.

By providing a fluororesin film on at least the side surface of the sealing plate and the inner surface of the through hole of the sealing plate using a rubber-coated paper phenol insulating plate, it is not easy for the surface to be eroded by the electrolyte even at high temperatures. This prevents the chlorine from flowing into the capacitor from this sealing plate, and the chlorine adhering to the evaporated electrolyte may react with the aluminum of the rivet part and the lead tab of the lead to corrode the rivet part and the lead lead tab. Can be reduced.
Moreover, a sealing board can be procured at low cost by using the sealing board using the rubber | gum sticking paper phenol insulation board currently distribute | circulating in the market.

The rubber-coated paper phenol insulating plate described in the present invention is generally distributed as a capacitor in which a rubber sheet is bonded to a paper phenol insulating plate, and is processed into a sealing plate according to the shape of the capacitor. As a paper phenol insulating board, a paper base material is used which is impregnated with a phenol resin before cross-linking dissolved in alcohol or the like, dried and then heat-cured and cured. Further, butyl rubber, ethylene propylene rubber, or the like is used as the rubber material of the rubber sheet.
The phenol resin has a low chlorine ion concentration, preferably about 10 ppm or less, and a filler having a low chlorine ion concentration, preferably about 10 ppm or less. The phenol resin used in the present invention is a novolac type. A resol type or a modified product may be used, but a low chloride ion concentration is preferred.
In addition, an ionic substance blocking resin film such as polyethylene, polypropylene, a copolymer of ethylene and propylene, a polyphenylene sulfide film, a fluororesin film, or the like may be laminated on the back surface of the rubber-coated paper phenol insulating plate, and bonded and integrated. It doesn't matter.

The external terminal described in the present invention is an external terminal that penetrates a sealing plate of a type in which an insulating plate and a rubber plate are bonded together. For example, a rivet and a metal plate terminal attached thereto are provided from the rubber plate side, and the tip of the rivet is a sealing plate. A fixing washer or the like is inserted into the tip of the rivet from the insulating plate side to fix the external terminal to the sealing plate. Instead of a washer for fixing, the rivet may be transformed into a similar shape. In some cases, the rivet is inserted into the sealing plate in the reverse direction, and the tip of the rivet is crimped after the metal plate terminal is inserted into the rubber plate side. In this case, a columnar protrusion is provided on the head portion of the rivet, and a lead lead tab drawn out from the capacitor element is connected.

The fluororesin film described in the present invention is a film made of a soluble or solvent-dispersible fluororesin, and the thickness of the film is 1 nm to 50 μm, preferably 5 nm to 10 μm. If it is thinner than 1 nm, it is difficult to obtain a continuous film.
Examples of the fluororesin of the present invention include tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE), Examples include tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), hexafluoropropylene-vinylidene fluoride copolymer (HV), and polyvinylidene fluoride (PVDF). Let
As the additive, a silane coupling agent or the like may be used.
Examples of the solvent for dissolving the fluororesin described in the present invention include acetone, methyl ethyl ketone, nitrobenzene, hydrofluoroethers such as methylnonafluoroisobutyl ether and methylnonafluorobutyl ether, N-methyl-pyrrolidone, dimethylsulfoxide and dimethylformamide, cyclohexanone, Examples include isophorone.
The process of providing the fluororesin film is performed after the rubber-coated paper phenol insulation board is provided in the through hole for the external terminal penetrating the sealing board by punching or drilling or by external processing of the sealing board by punching or the like. This is performed before the external terminal is provided in the through hole for the external terminal.
The fluororesin film forming method is performed by dissolving the fluororesin in a solvent that dissolves the fluororesin and impregnating the solution in the solution. Also, a coating method such as air spray may be used. After coating, the solvent is evaporated by heating, and the polymerizable resin is polymerized and solidified. This impregnation-solidification step is preferably repeated at least twice from the viewpoint of preventing pin poles of the resulting film. It may be repeated three or more times.
A rubber plate is attached to one side of the sealing plate of the present invention, and an ionic substance blocking resin film is optionally attached to the back side. The fluororesin is deposited on at least the side surface of the sealing plate and the inner surface of the through hole.
The side surface of the sealing plate and the inner surface of the through-hole can reinforce adhesion between the fluororesin and the sealing plate by providing unevenness by machining or intentionally. In addition, the paper phenol insulation board is a laminated sheet of paper base material, so that the paper base material is exposed on the side surface of the sealing plate that is a cross section and the inner surface of the through hole, and there is a gap between the paper base material and the phenol resin. If it occurs, the fluororesin solution of the present invention can permeate into the gap to reinforce the adhesion between the fluororesin and the sealing plate and prevent the electrolyte from entering. In order to improve the permeability, it is preferable to reduce the viscosity of the fluororesin solution. Therefore, the fluororesin concentration is 0.01 to 10%, preferably about 0.1 to 5%. If it is less than 0.01%, the repetition of the impregnation-solidification step increases, which is not preferable.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 shows a cross-sectional view of an aluminum electrolytic capacitor according to the present invention.
The aluminum electrolytic capacitor according to the present invention is a capacitor element in which an electrode foil is cut to an appropriate width and then a lead lead tab 1 is connected and wound or laminated together with a separator such as paper in the same manner as a normal aluminum electrolytic capacitor. The sealing plate 3 is connected to 2 and made of a metal material such as aluminum having an open upper surface, and is housed in a case 4 that is formed in a cylindrical or elliptical cylindrical shape in appearance. The case 4 may be covered with an insulating tube.
The sealing plate 3 has a rubber phenolic plate 7 bonded to the surface of a paper phenol insulating plate 5 on the back side thereof, and a fluororesin film on the side surface of the sealing plate and the inner surface of the through hole. 8 is deposited.
The external terminal 9 includes a pair of positive and negative rivets 11 that are attached so as to penetrate the sealing plate 3 through holes 10 for penetrating the external terminals, and a plate-like terminal 12 that is connected to the rivet 11 and connected at the other end to the outside. , A fixing washer 13 inserted from the tip of the rivet 11 for fixing to the sealing plate 3, a hole in the lead lead tab 1 pulled out from the capacitor element 2, a hole in the end, and insertion into the rivet 11, Further, a caulking washer 14 is inserted into the rivet 11 and connected.

  FIG. 2 shows a cross-sectional view of a sealing plate of another configuration before external terminal mounting. In FIG. 2A, a rubber plate 6 is bonded to the surface of a paper phenol insulating plate 5 with an ionic substance blocking resin film 7 on the back side, and fluorine is applied to the entire surface of the sealing plate and the inner surface of the through hole. A resin film 8 is applied. In FIG. 2B, the rubber plate 6 is bonded only to the surface of the paper phenol insulating plate 5, and the fluororesin film 8 is adhered to the entire surface of the sealing plate and the inner surface of the through hole.

Hereinafter, the present invention will be described based on examples. In addition, an Example demonstrates the case where an electrolytic capacitor of rated 400V and 560 micro F is manufactured.
First, a sealing plate is prepared. A 1 mm thick butyl rubber plate is bonded to the surface of a 2 mm thick paper phenolic insulating plate, and a polypropylene is bonded to the back side as a 100 μm thick ionic substance-blocking resin film. And a through hole for an external terminal penetrating the sealing plate. Next, after impregnation in a 0.5% concentration solution in which a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) is dissolved in a solvent, the solution is taken out and heated to evaporate and solidify the solvent. This impregnation-solidification was repeated twice. Next, a rivet and a metal plate terminal attached thereto were provided on the rubber plate side, and a fixing washer was inserted from the end of the rivet from the insulating plate side to fix the external terminal to the sealing plate.
Next, the anode foil is manufactured by processing an aluminum foil having a thickness of about 100 μm. That is, the aluminum foil is roughened by direct current and chemical etching. After roughening, boil in pure water. After boiling, a chemical film is formed by applying a direct current voltage of 600 V in a boric acid chemical liquid. After the chemical conversion treatment, phosphoric acid treatment is performed for stabilization, followed by baking at a temperature of 550 ° C. After the firing treatment, it is cut into a size of 40 mm in width and 3000 mm in length to obtain an anode foil.
Further, an aluminum foil having a thickness of 150 μm, a width of 5 mm, and a length of 60 mm, which has been subjected to chemical conversion treatment at 600 V without etching, is used for the lead tab for the anode. The anode lead tab is connected to the anode foil by cold welding.
As the cathode foil, an aluminum foil having a thickness of 30 μm is etched and phosphoric acid-treated, and about 200 μF / cm ² is used. The cathode foil is cut into a size of 40 mm in width and 3050 mm in length.
The cathode lead tab is manufactured by rolling an aluminum foil to a length of 150 μm and a width of 1000 mm, followed by annealing, cutting to a width of 500 mm, and further cutting to a size of 5 mm. The cathode lead tab is connected to the cathode foil by cold welding.
As the electrolytic paper, paper having a width of 50 mm was used, and kraft paper having a thickness of 60 μm and a density of 0.75 g / cm ³ was used.
An anode foil and a cathode foil were laminated and wound through this electrolytic paper to form a capacitor element. Thereafter, an organic acid electrolyte solution of ethylene glycol and ammonium 2-butyloctanedioate was impregnated.
After impregnating the electrolytic solution, the anode lead tab and the cathode lead tab drawn out from the capacitor element were respectively connected to the anode terminal and the cathode terminal provided through the sealing plate. After the connection, the capacitor element was stored in the case. After storage, a sealing plate was attached to the end of the case, and the case was sealed. After the case was sealed, it was left in an atmosphere at a temperature of 85 ° C. and a voltage of 425 V was applied for aging treatment. After the aging treatment, the case was covered with an insulating tube.

Example 3 was produced in the same manner as Example 1 except that the coating resin was changed as shown in Table 1. When the inner surface state of the sealing plate case after leaving the rated voltage applied for 2000 hours at a high temperature of 130 ° C. is observed together with the conventional example 1 where coating is not performed, corrosion is seen in the lead tab portion of the case coated with fluororesin. Although there was no corrosion, the lead tab portion in the uncoated case was corroded. The chloride ion concentration in the electrolytic solution after the rated voltage application test is as shown in Table 1. When a fluororesin is applied, chlorine outflow from the sealing plate is prevented.

1 shows a cross-sectional view of an aluminum electrolytic capacitor according to the present invention. Sectional drawing of the sealing board of another structure before the external terminal mounting | wearing which concerns on this invention is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lead lead tab, 2 ... Capacitor element, 3 ... Sealing plate, 4 ... Case, 5 ... Paper phenol insulation board, 6 ... Rubber plate, 7 ... Ion substance blocking resin film, 8 ... Fluorine resin film, 9 ... External Terminals 10, holes for penetrating external terminals, 11 rivets, 12 plate terminals, 13 fixing washers, 14 caulking washers

Claims (2)

In an electrolytic capacitor having a sealing plate using a paper base rubber- coated paper phenol insulating plate, a through hole provided in the sealing plate, and an external terminal penetrating the through hole, at least the side surface of the sealing plate and the through hole An electrolytic capacitor, wherein a coating film of a fluororesin of tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer or hexafluoropropylene-vinylidene fluoride copolymer is provided on an inner surface.   Tetrafluoroethylene-hexafluoro in a method for producing an electrolytic capacitor having a sealing plate using a paper-based rubber-coated paper phenol insulating plate, a through-hole provided in the sealing plate, and an external terminal penetrating the through-hole Propylene-vinylidene fluoride copolymer or hexafluoropropylene-vinylidene fluoride copolymer dissolved solution is applied to at least the side surface of the sealing plate and the inner surface of the through hole to provide a fluororesin film. Manufacturing method of electrolytic capacitor.

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