JP2004221575A - Layered aluminium electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a layered aluminium electrolytic capacitor in which the size is reduced furthermore by eliminating the margin of a separator. <P>SOLUTION: The layered aluminium electrolytic capacitor comprises an aluminium electrolytic capacitor element stacking an anode foil, a cathode foil and an interposed separator, external lead-out terminals bonded, respectively, to the anode foil and the cathode foil of the capacitor element and led out to the outside of a containing case, and lead terminals connected, respectively, with these external lead-out terminals, all of which are encased in the containing case being sealed hermetically. The separator 4 is folded to the inside of the stack at least at two positions to wrap the anode foil 2 (or the cathode foil) at least partially. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an aluminum electrolytic capacitor. More specifically, the present invention minimizes the margin between the electrode foil (anode foil and cathode foil) and the separator to facilitate miniaturization of the aluminum electrolytic capacitor, and prevents short-circuiting due to the displacement of the separator, thereby improving productivity. The present invention relates to a multilayer aluminum electrolytic capacitor having improved characteristics.

  Conventional aluminum electrolytic capacitors generally have a capacitor element that is wound with a separator interposed between two electrode foils (anode foil and cathode foil) and housed in a cylindrical metal case, and have an external lead-out terminal. It is configured by closing the metal case opening with the terminal plate.

  In recent years, as electronic devices have been reduced in size and thickness, conventional cylindrical aluminum electrolytic capacitors are much larger than other electronic components and take up considerable space on a substrate. In addition to the cylindrical type, there is also a flat type, but there are restrictions on the size of the product, which hinders a thin and compact product. Therefore, there is a demand for a product having a shape different from that of the related art in accordance with a space for accommodating parts of an electronic device. To cope with this, an electrolytic capacitor having a hermetically sealed structure using a composite film as disclosed in JP-A-55-143024 and JP-A-58-178517 has been proposed. An electrolytic capacitor having a sealed structure using such a composite film can be formed into an external shape according to the shape of the capacitor element, and is not limited to a conventional cylindrical shape, but may be any shape such as a square, a sheet, and an ellipse. This makes it possible to use an electrolytic capacitor having a shape, and is extremely effective in realizing miniaturization and thinning of a device using the electrolytic capacitor.

  As a capacitor element sealed with a composite film, a capacitor element having a laminated structure in which an anode foil, a separator, and a cathode foil are laminated has been proposed.

  JP-A-59-123220, JP-A-56-135923, and JP-A-4-223317 disclose a capacitor element having a laminated structure in which a separator is interposed between an anode foil and a cathode foil. In order to prevent short-circuiting, the separator is slightly larger (with a margin) than the size of the anode foil and the cathode foil. Or a zigzag bent separator with a plate-shaped anode foil and a zigzag bent cathode foil.

  A separator having a margin from the electrode foil disclosed in JP-A-59-123220 and a two-folded separator disclosed in JP-A-56-135923 (also in this case, the separator is a portion other than the fold). A product capacitor sealed with a composite film using a cathode foil folded in a zigzag pattern and a separator folded in a zigzag pattern will be larger by the margin. When a cathode foil separator bent in a zigzag pattern is used as described in JP-A-4-223317, the anode foil also has ears located outside the laminate, which is advantageous in terms of the laminated structure of the capacitor. It is disadvantageous for certain miniaturization.

  On the other hand, in the case of manufacturing a multilayer capacitor element using a separator having no fold and no margin, there is a troublesome problem that the electrode foil is likely to be displaced during lamination and short circuit is likely to occur.

JP-A-55-143024 JP-A-58-178517 JP-A-59-123220 JP-A-56-135923 JP-A-4-223317

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a more compact laminated aluminum electrolytic capacitor by eliminating the margin of the separator.

  The laminated aluminum electrolytic capacitor of the present invention is sealed in a storage case, a laminated aluminum electrolytic capacitor element comprising an anode foil and a cathode foil and a separator located therebetween, an anode foil of the capacitor element and An aluminum electrolytic capacitor having an external lead terminal joined to the cathode foil and pulled out of the storage case, and a lead terminal connected to each of the external lead terminals, wherein the separator is an anode foil or a cathode foil. It is characterized in that it is folded at least two places inside the laminate so as to at least partially wrap it.

  According to the present invention, by eliminating the margin of the separator with respect to the electrode foil while reliably separating the anode foil and the cathode foil, it is possible to use a more compact laminated aluminum electrolytic capacitor.

  The present invention can be applied to various aluminum electrolytic capacitors. Examples of suitable aluminum electrolytic capacitors include, but are not limited to, aluminum electrolytic capacitors for low voltage up to 100 V, aluminum electrolytic capacitors for medium and high voltage of 100 V or more, aluminum electrolytic capacitors for strobe flash, etc. is there.

  The aluminum electrolytic capacitor of the present invention includes a storage case, an aluminum electrolytic capacitor element sealed and stored in the storage case, and an external lead terminal drawn out of the storage case from the anode foil and the cathode foil of the capacitor element. Have.

  The storage case can be made of any material capable of sealing and storing the capacitor element by enclosing the capacitor element, and this material may be soft or hard.

  For example, the storage case can be made of a metal material. In this case, the capacitor element can be sealed in the metal case by laser welding, resistance welding, pressure bonding, or the like. The capacitor element is insulated from the metal case by a separator surrounding the capacitor element, while the external lead-out terminal connected to the electrode of the element is insulated from the metal case by an insulating material at a portion taken out of the storage case to the outside. As the metal material, aluminum or an alloy of aluminum is preferable in terms of availability, but other metal materials can also be used.

  Resin can be used as the storage case material. The resin may be thermoplastic or thermoset. In the case of a thermosetting resin, by using a thermosetting resin sheet attached to the case, the case can be thermally welded to seal the capacitor element. In addition to heat welding, sealing can be performed by bonding with an adhesive, ultrasonic welding, hermetic sealing, laser welding, pressure bonding, or the like. Thermoplastic resin can seal the capacitor element by heat-sealing the adhesive part for sealing, but it is also possible to seal with an adhesive, ultrasonic welding, hermetic seal, laser welding, crimping, etc. is there. As the resin material, for example, nylon, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), liquid crystal polymer, engineering plastic, polyethylene, polystyrene, fluorine resin, polyamide, etc. are possible. Alternatively, a material having improved heat resistance by adding a filler such as a glass filler to these resins is also effective. The resin material is not limited to these, and other materials may be used.

  Preferred for the aluminum electrolytic capacitor of the present invention is a flexible case because the capacitor element is easily sealed. A typical example is made of a composite material (laminated material) composed of a laminated metal layer and a resin layer. The basic layer configuration of this composite material is a laminated structure in which resin layers are located on both sides of a metal layer.

  As the material of the metal layer in the composite material, aluminum, copper, nickel, titanium, or an alloy thereof is preferable. Most preferred is aluminum or an aluminum alloy because it is the easiest to obtain. The thickness of the metal layer is preferably from 5 to 300 μm, and most preferably from 5 to 200 μm. If the metal layer is too thick, it becomes difficult to process the composite material and seal the storage case, and if it is too thin, the sealing becomes insufficient, which may cause liquid leakage.

  As the material of the resin layer, nylon, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyimide, and the like are preferable. The most preferable resin material is nylon or PET because of availability. The thickness of the resin layer is preferably from 5 to 100 μm, and most preferably from 5 to 50 μm. When the resin layer is thick, it becomes difficult to process the composite material and to seal the storage case, and when the resin layer is too thin, the sealing becomes insufficient, which may cause liquid leakage.

  An adhesive layer may be provided on the side of the composite material that is in contact with the capacitor element (the side that is inside the storage case). The adhesive layer may be a resin layer on the side in contact with the capacitor element in the basic laminated structure of the resin layer, the metal layer, and the resin layer of the composite material, or may be separately provided on the resin layer on the side in contact with the capacitor element. It may be a layer. The adhesive layer is formed of a resin effective for sealing the capacitor element in the storage case by the adhesive action. As the adhesive layer resin, polypropylene (PP), polyethylene (PE), an acid-modified product thereof, an ionomer, or the like can be used. The thickness of the adhesive layer is preferably from 10 to 200 μm, most preferably from 20 to 100 μm.

  The thickness of the composite material is preferably from 20 to 600 μm, most preferably from 30 to 500 μm. When the resin layer is thick, it becomes difficult to process the composite material and to seal the storage case, and when the resin layer is too thin, the sealing is insufficient and the liquid may leak.

  The aluminum electrolytic capacitor element is manufactured as a capacitor element having a laminated structure. Specifically, the high-purity aluminum foil is etched to increase the surface area, the anode foil whose surface is anodized to be a dielectric, and the aluminum cathode foil which is opposed to the anode foil and whose surface is etched, A laminated body composed of a separator (separator) impregnated with an electrolytic solution interposed between the anode foil and the cathode foil is a capacitor element having a laminated structure. In the capacitor element having a multilayer structure, a configuration including a plurality of the above-described multilayer bodies is also possible. Such capacitor elements themselves are widely known and need not be described in further detail here.

  For the separator, natural cellulose fibers, synthetic fibers such as viscose rayon fibers, polypropylene fibers, polyimide fibers, and polyvinyl alcohol fibers, or a mixture of natural cellulose fibers and synthetic cellulose fibers can be used as a raw material. Natural cellulose fibers are preferred from the viewpoint of processability and cost.

  In the laminated aluminum electrolytic capacitor of the present invention, the separator is folded inside the laminate so as to at least partially wrap one of the anode foil and the cathode foil.

  The separator according to the present invention will be described with reference to the drawings. FIG. 1A shows a mode in which the anode foil 2 is partially wrapped by the separator 4, and reference numeral 3 in the drawing denotes an external lead lead joined to the anode foil 2. The separator 4 is bent along both sides in the longitudinal direction of the anode foil such that the respective ends 4a and 4b are located in the region of the anode foil 2, and the separator 4 is a laminate of the electrode foil and the separator. Is folded inside. As a result, the width of the separator after being folded is substantially equal to the width of the anode foil, and the thickness of the part folded inside the separator causes the anode foil 2 in the laminate and the cathode foil ( (Not shown), so that miniaturization of the product capacitor and prevention of short circuit can be realized at the same time.

  In the separator 4 of FIG. 1A, a gap is provided between the front ends 4a and 4b of the folded portions from both sides, and this gap is a danger of short-circuit due to contact between the electrode foils due to deformation of the laminated electrode foils. Can be widened or narrowed depending on the degree of In some cases, it is possible to overlap one folded portion with the other (for example, extend one end 4a of FIG. 1A to a region below 4b).

  In the embodiment shown in FIG. 1B, the anode foil 2 is bent into the region of the anode foil 2 along both sides in the longitudinal direction until the respective ends 4 a and 4 b come into contact with each other, and the left side ( The left side part 4 ′ is also directed into the area of the anode foil 2 so as to eliminate the margin of the separator on the side opposite to the side from which the external lead-out terminal is drawn out, and to make contact with the part folded from both sides in the longitudinal direction. It is folded. As a result, the anode foil 4 of this embodiment is substantially entirely wrapped by the separator.

  Of course, the electrode foil wrapped in the separator may be either an anode foil or a cathode foil. Further, in one capacitor, it is also possible to laminate and use an anode foil and a cathode foil both wrapped by a separator.

  As described above, by using the separator folded inside the laminate in accordance with the outer dimensions (eg, “width”) of the electrode foil (anode foil or cathode foil) at least at two places, the outer dimensions of the electrode foil can be reduced. It is possible to use a capacitor element that is very close, thereby realizing miniaturization of a product capacitor. The separator is integrated with the electrode foil (anode or cathode foil) that it wraps when laminated with the electrode foil, so there is no risk of misalignment and therefore no risk of capacitor element short-circuit, and the productivity of the capacitor is reduced. Can also be improved.

  An external lead-out terminal for connecting the anode foil and the cathode foil to an external circuit is attached to the aluminum electrolytic capacitor element. The external lead-out terminal facilitates attachment of the lead terminal connected thereto, facilitates sealing of the lead-out portion from the storage case, and absorbs movement of the capacitor body housed in the outer case. , A film or a foil strip. In addition, since the external lead terminal is attached to the aluminum electrode foil, it is preferable that the external lead terminal be made of aluminum or an aluminum alloy.

  A lead terminal is connected to the external lead-out terminal in order to reduce the resistance of the capacitor and improve the workability of soldering when mounting the capacitor on a circuit board or the like. Lead terminals can be made from materials that have low electrical resistance and can be soldered. Suitable materials include iron, copper, tin, lead, silver, gold, zinc, bismuth, tungsten, nickel, titanium and chromium. And a metal material containing at least one metal selected from the group consisting of: The lead terminal can have any shape, such as a linear shape or a sheet shape, which allows the capacitor to be mounted on a circuit board or the like. The connection between the external lead terminal and the lead terminal is performed by, for example, ultrasonic welding, laser welding, resistance welding, or crimping.

  The aluminum electrolytic capacitor of the present invention may be housed in an outer case as disclosed in Japanese Patent Application No. 2002-320203.

  As the outer case, a cylindrical case having an arbitrary cross-sectional shape can be used according to the shape of the capacitor in which the capacitor element is stored in the storage case. Examples of the material of the outer case include a metal or resin sheet. The metal is preferably aluminum or an aluminum alloy, and other metal materials can be used. The resin is preferably nylon or PET, and other resins can also be used.

  The outer case can be manufactured by any method. For example, in the case of an outer case made of resin, it can be manufactured by facing two U-shaped members formed from a resin sheet and joining two overlapping sides. To facilitate joining, a thermoplastic resin film may be attached to a resin sheet of a case material. As the thermoplastic resin, a polyester resin, a polyamide resin, and an acid-modified polyolefin resin can be used. The thickness of the resin sheet is preferably from 50 to 500 μm, and most preferably from 100 to 300 μm. When a thermoplastic resin is used for bonding, the thickness is preferably from 10 to 300 μm, and most preferably from 30 to 100 μm.

  In order to prevent the capacitor from coming off the outer case, it is preferable to fix the capacitor to the outer case. This fixation is also useful for reducing stress on the junction between the capacitor element and the external lead-out terminal and the lead terminal. The fixing method may be, for example, bonding with an adhesive, heat fusion, ultrasonic welding, hermetic sealing, laser welding, or crimping.

  When an outer case is used, one end can be sealed with a sealing material, and the lead terminal can penetrate the sealing material, as also disclosed in Japanese Patent Application No. 2002-320203. . The lead terminal penetrating the sealing material is integrated with the sealing material at the penetrating portion.

  The sealing material can be made of a material such as rubber, composite rubber, and resin. Suitable rubber materials include resin vulcanized butyl rubber, peroxide vulcanized butyl rubber, ethylene propylene rubber (EPT), styrene butadiene rubber, or a blend rubber of butyl rubber and EPT. A typical example of a composite rubber material is one in which a material such as polytetrafluoroethylene (PTFE), a base material, a glass fiber sheet, or polypropylene is adhered to one of the rubber materials described above. As the resin material, a thermosetting resin or a thermoplastic resin can be used. For example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), nylon, polyphenylene sulfide (PPS), liquid crystal polymer, engineering plastic, and the like can be used. Yes, or a material obtained by adding a filler such as glass filler to PET, PBT, nylon or PPS to improve heat resistance is also effective.

  The sealing of one end of the outer case with the sealing material can be performed by inserting a sealing material formed in advance into the opening of the outer case and closely contacting the sealing material. The close contact between the outer case and the sealing material is performed by, for example, bonding with an adhesive, heat fusion, ultrasonic welding, hermetic sealing, laser welding, or crimping. The size of the sealing material may be smaller than the opening of the outer case, but it must be in close contact with at least a part of the opening.

  When a sealing material is not used, it is also possible to connect the lead terminals with an insulating material and integrate them.

  Next, examples of the aluminum electrolytic capacitor of the present invention are shown together with conventional examples, but the present invention is not limited to the following examples.

  As a laminated aluminum electrolytic capacitor sample, a capacitor element having a laminated electrode structure with a rated voltage of 330 V and 100 μF was produced. The separator used was a cellulosic fiber having a thickness of 30 μm. The electrode foil had a width of 16 mm for both the anode and the cathode, and an external lead was attached to each. For each of the following examples, 35 sets of devices in which the separator, the anode foil, and the cathode foil were laminated were produced.

Conventional Example 1 is an example of an element manufactured by laminating separators without any breakage. A margin of 1 mm was provided around the separator with respect to the electrode foil.
Conventional examples 2 and 3 are examples of devices fabricated by laminating together with a cathode using a separator that is folded in two and sandwiching an anode between them. The margin (width direction) between the separator and the electrode foil was 1 mm in Conventional Example 2 and 0 mm in Conventional Example 3.

Example 1 is an example in which a separator is used which is folded so as to completely wrap the anode foil from both sides in the width direction of the anode foil.
Example 2 is an example in which separators are used which are folded at three places so as to completely wrap the anode foil from both sides in the width direction of the anode foil and from the side opposite to the side where the external lead is attached.

  Table 1 shows the results of checking the presence / absence of a short circuit between the two electrodes using a tester. In the numerical values shown in the column of the number of shorts in Table 1, the left side shows the number of samples in which shorts are recognized, and the right side shows the total number of samples.

  In Conventional Examples 1 and 2, there is a margin of the separator with respect to the electrode foil, and there is no danger of contact between the bipolar foils even at the fold portion of the separator of Conventional Example 2, so that the number of short circuits in both samples was zero. However, in each of the examples, the element width was larger by the margin than the width of the electrode foil itself. In Conventional Example 3, since the margin of the separator with respect to the electrode foil was not secured, the element width could be manufactured to be substantially the same as the width of the electrode foil. % Of samples showed a short circuit.

  In Examples 1 and 2, there is no margin of the separator with respect to the electrode foil, so that the element width can be made substantially the same as the electrode foil. I was not able to admit.

It is a figure explaining the mode of the separator used by the present invention.

Explanation of reference numerals

2 ... Anode foil 3 ... External lead 4 ... Separators 4a and 4b ... End of separator

Claims (21)

  The aluminum electrolytic capacitor element of a laminated body composed of an anode foil and a cathode foil and a separator located therebetween, which is sealed in the storage case, and bonded to the anode foil and the cathode foil of the capacitor element, respectively. What is claimed is: 1. A laminated aluminum electrolytic capacitor having an external lead-out terminal drawn out to the outside and lead terminals connected to these external lead-out terminals respectively, wherein at least a part of the separator is provided so as to at least partially wrap the anode foil or the cathode foil. A multilayer aluminum electrolytic capacitor, wherein the multilayer aluminum electrolytic capacitor is folded inside the multilayer body at a location.   The multilayer aluminum electrolytic capacitor according to claim 1, wherein tips of the folded portions of the separator are separated from each other.   The multilayer aluminum electrolytic capacitor according to claim 1, wherein tips of the folded portions of the separator are in contact with each other.   The multilayer aluminum electrolytic capacitor according to claim 1, wherein one folded portion of the separator overlaps the other folded portion.   The multilayer aluminum electrolytic capacitor according to claim 1, wherein the separator is folded into the inside of the multilayer body from three directions.   The multilayer aluminum electrolytic capacitor according to any one of claims 1 to 5, wherein the storage case is made of a composite material in which a metal layer and a resin layer are laminated.   The multilayer aluminum electrolytic capacitor according to claim 6, wherein the material of the metal layer is aluminum, copper, nickel, titanium, or an alloy thereof.   8. The multilayer aluminum electrolytic capacitor according to claim 6, wherein the material of the resin layer is nylon, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide or polyimide.   The multilayer aluminum electrolytic capacitor according to any one of claims 6 to 8, wherein an adhesive layer is located on a side of the composite material that contacts the capacitor element.   The multilayer aluminum electrolytic capacitor according to claim 9, wherein the material of the adhesive layer is polypropylene, polyethylene, an acid-modified product thereof, or an ionomer.   11. The method according to claim 1, wherein the lead terminal includes at least one metal selected from iron, copper, tin, lead, silver, gold, zinc, bismuth, tungsten, nickel, titanium and chromium. 4. The multilayer aluminum electrolytic capacitor described in any one of the above.   The multilayer aluminum electrolytic capacitor according to any one of claims 1 to 11, which is housed in an outer case.   13. The multilayer aluminum electrolytic capacitor according to claim 12, wherein a material of the outer case is a metal or resin sheet.   14. The multilayer aluminum electrolytic capacitor according to claim 13, wherein the metal is aluminum or an alloy of aluminum.   14. The multilayer aluminum electrolytic capacitor according to claim 13, wherein the resin is nylon or polyethylene terephthalate.   The multilayer aluminum electrolytic capacitor according to claim 15, wherein a thermoplastic resin film is bonded to the resin sheet.   17. The multilayer aluminum electrolytic capacitor according to claim 16, wherein the thermoplastic resin film is a film of a polyester resin, a polyamide resin, or an acid-modified polyolefin resin.   18. The multilayer aluminum electrolytic capacitor according to claim 12, wherein one end of the outer case is sealed with a sealing material, and the lead terminal penetrates the sealing material.   The multilayer aluminum electrolytic capacitor according to claim 18, wherein the material of the sealing material is rubber, composite rubber, or resin.   The multilayer aluminum electrolytic capacitor according to claim 19, wherein the resin is a thermosetting resin or a thermoplastic resin.   The material of the sealing material is polyethylene terephthalate, polybutylene terephthalate, nylon, polyphenylene sulfide, liquid crystal polymer, engineering plastic, polyethylene terephthalate with glass filler, polybutylene terephthalate with glass filler, nylon with glass filler, or polyphenylene sulfide with glass filler. 20. The multilayer aluminum electrolytic capacitor according to claim 19.

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