JP2006253458A - Chip type aluminum electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip type aluminum electrolytic capacitor whose product cycle is improved by suppressing its sealing body from deforming after its spinning. <P>SOLUTION: The chip type aluminum electrolytic capacitor has: a capacitor element wherein an anode foil connected with an anode lead and a cathode foil connected with a cathode lead wind together with a separator; a driving electrolyte wherewith the capacitor element is impregnated; a bottomed cylindrical metal case having the capacitor element integrated thereinto; and a sealing body for sealing therewith the opening portion of the metal case. An annular recess is so provided in the side surface of the sealing body as to fit to the shape of the annular recess a protrusion of the metal case spinned from the outside of the metal case. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chip-type aluminum electrolytic capacitor used in various electronic devices.

  FIG. 3 is a cross-sectional view showing the configuration of a chip-type aluminum electrolytic capacitor capable of high-density mounting among electrolytic capacitors. In the figure, a capacitor element 22 having a pair of lead members 21 and impregnated with a driving electrolyte (not shown), a sealing body 23, an exterior metal case 24, and an insulating plate 25, The pair of lead members 21 drawn out from the capacitor element 22 are passed through the sealing body 23, the capacitor element 22 is accommodated in the metal case 24, and the opening of the metal case 24 is put together with the sealing body 23. The drawn portion 26 is drawn, and the curled portion 27 is curled and sealed, the pair of lead members 21 are passed through the insulating plate 25, and the distal ends of the pair of lead members 21 are bent. It is housed in a housing recess 28 provided on the outer surface of the insulating plate 25.

  As the driving electrolytic solution, an organic solvent such as ethylene glycol or γ-butyrolactone and a solute of boric acid or ammonium borate is used. In addition, those using azelaic acid, butyloctanedioic acid, 5,6-decanedicarboxylic acid, 1,7-octanedicarboxylic acid, etc. as solutes can reduce the moisture in the driving electrolyte solution, so It is said that the valve opening of the electrolytic capacitor due to an increase in the internal pressure of moisture can be suppressed even under the environment.

  The sealing body 23 is made of styrene butadiene rubber (SBR), ethylene-propylene copolymer rubber (EPM), ethylene-propylene-diene terpolymer rubber (EPDM), or isobutylene-isoprene copolymer. Rubber (IIR) or the like is used, and is selected according to the composition of the driving electrolyte. However, since the sealing body 23 curls and seals the opening of the metal case 24, the sealing body 23 has an elastic characteristic. It is important.

  By mounting such a chip-type aluminum electrolytic capacitor on a printed circuit board, it is said that the insulating plate 25 can be mounted stably and accurately.

  The chip-type aluminum electrolytic capacitor has a metal case 24 having a diameter of φ3 to 20 mm, and the size of the insulating plate 25 is adjusted to the size of the metal case.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP-A-11-186115

  In the conventional chip type aluminum electrolytic capacitor, the sealing body 23 has a cylindrical shape, and when the side surface is drawn from the outside of the metal case 24, the sealing body 23 is deformed as shown in FIG. Inadvertent stress is applied to the element 22 and cracks are generated, resulting in a problem that the product life of the aluminum electrolytic capacitor is shortened. In particular, the outer diameter of the sealing body 23 appears more noticeably as 10 mm or less.

  This is because when the metal case 24 is drawn, the pressure applied to the sealing body 23 is concentrated at one point, and the stress escapes to the flat surface side of the sealing body 23. It is thought that a crack occurs in the part.

  An object of the present invention is to provide a chip-type aluminum electrolytic capacitor that solves such a conventional problem and improves the product life by suppressing deformation of the sealing body after drawing.

  In order to solve the above problems, the present invention provides a capacitor element in which an anode foil connected with an anode lead and a cathode foil connected with a cathode lead are wound together with a separator, a driving electrolyte impregnated in the capacitor element, It has a bottomed cylindrical metal case containing a capacitor element, and a sealing body that seals the opening of the metal case. An annular recess is provided on the side of the sealing body, and is drawn from the outside of the metal case. The protrusion is adapted to follow the shape of the annular recess.

  The chip-type aluminum electrolytic capacitor of the present invention is provided with an annular recess on the side surface of the sealing body, and the protrusions drawn from the outside of the metal case are made to follow the shape of the annular recess so that the entire annular recess of the sealing body Since the pressure is uniformly applied to the capacitor, deformation of the sealing body can be suppressed, and thereby stress on the capacitor element can be reduced. In addition, since the contact area between the sealing body and the metal case can be increased, leakage of the electrolytic solution can also be reduced, so that the product life can be improved.

  Hereinafter, an embodiment of the present invention will be described in detail.

  FIG. 1 is a cross-sectional view showing a configuration of a chip-type aluminum electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a perspective view of a sealing body. In FIG. 1, reference numeral 11 denotes a capacitor element. The capacitor element 11 has an aluminum foil on which a dielectric oxide film is formed by a chemical conversion treatment after the surface is roughened as an anode foil, and the anode foil and the cathode foil are interposed therebetween. And is wound by interposing a separator. Reference numerals 12 and 13 are anode leads and cathode leads drawn from the anode foil and the cathode foil of the capacitor element 11, respectively, and 14 is provided with a through hole 16 through which the anode lead 12 and the cathode lead 13 pass. It is the sealing body which has the elasticity which seals the opening part. After the capacitor element 11 is inserted into the metal case 17 together with a driving electrolyte (not shown), the anode lead 12 and the cathode lead 13 are inserted through the through hole 16 of the sealing body 14 and inserted into the opening of the metal case 17, The opening of the metal case 17 is bent inward to press the sealing body 14, and the outside of the metal case 17 is drawn to seal the side surface of the sealing body 14. In this drawing process, since the side part of the sealing body 14 has the shape of the annular recess 15, the drawing part 18 is formed along the annular recess 15 by drawing from the outside of the metal case 17. Like to do.

  Finally, the anode lead 12 and the cathode lead 13 are passed through the insulating seat plate 19, and the tips of the leads 12 and 13 are bent and disposed on the outer surface of the insulating seat plate 19. Yes.

  In addition, the sealing body 14 is kneaded by adding a crosslinking agent, a crosslinking aid, a reinforcing material or a filler, a deterioration preventing agent or the like to butyl rubber, and thereafter molded and processed in a vacuum, and further subjected to secondary crosslinking in a vacuum. The sealing body 14 can be obtained by annealing.

  The shape of the sealing body 14 is a cylindrical elastic body having a diameter of 4 to 10 mm and a thickness of 2 to 6 mm, and an R-shaped annular recess having a radius of curvature of about 1/2 or more of the diameter on the side surface thereof. Is formed.

  As the driving electrolyte solution, a solution selected from one or more of ethylene glycol, γ-butyrolactone, propylene carbonate, sulfolane, and water is used, and an organic acid or inorganic acid, or an organic acid or inorganic acid ammonium salt or A material containing an electrolyte salt selected from any one or more of primary to quaternary ammonium salts or imidazolium salts and imidazolinium salts and derivatives thereof can be used.

  Examples of the organic acid or inorganic acid include formic acid, acetic acid, propionic acid, maleic acid, citraconic acid, phthalic acid, adipic acid, azelaic acid, benzoic acid, butyloctanoic acid, formic acid, decanedicarboxylic acid and the like, boron Examples thereof include inorganic acids such as acid and phosphoric acid, and primary to quaternary ammonium salts thereof can be used.

  Examples of the imidazolium salt, imidazolinium salt and derivatives thereof include imidazoline compounds, imidazole compounds, benzimidazole compounds, and alicyclic pyrimidine compounds quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group. Specifically, 1-methyl-1,8-diazabicyclo [5,4,0] undecene-7, 1-methyl-, which can provide an aluminum electrolytic capacitor with high conductivity and low loss, can be provided. 1,5-diazabicyclo [4,3,0] nonene-5, 1,2,3-trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,3-dimethyl-2-ethyl -Imidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2-heptylimidazolinini 1,3-dimethyl-2-(-3'heptyl) imidazolinium, 1,3-dimethyl-2-dodecylimidazolinium, 1,2,3-trimethyl-1,4,5,6-tetrahydro Pyrimidium, 1,3-dimethylimidazolium, and 1,3-dimethylbenzimidazolium are preferred.

  In addition, a conductive polymer layer such as polypyrrole, polythiophene, polyaniline, etc. is formed on the capacitor element by electrolytic polymerization or chemical polymerization, and used together with the driving electrolyte solution, so that the ESR can be reduced to a solder reflow temperature. In contrast, a stable aluminum electrolytic capacitor can be obtained.

  Further, the ESR can be further reduced by using the capacitor element having only the conductive polymer layer without using the driving electrolyte.

  Specific examples will be described below.

Example 1
Capacitor elements constructed by winding and interposing a Manila fiber separator between the anode foil connected to the anode lead and the cathode foil connected to the cathode lead, and γ-butyrolactone as a driving electrolyte, A material composed of mono (triethylamine) -phthalate, p-nitrobenzoic acid, and monobutyl phosphate was impregnated.

  After sealing the capacitor element together with the sealing body in a bottomed cylindrical aluminum metal case, the opening of the metal case is sealed by curling treatment, and the anode lead and cathode lead are passed through the insulating seat plate. In addition, by bending the tips of both leads and disposing them on the outer surface of the insulating seat plate, a chip-type aluminum electrolytic capacitor with a rated voltage of 35 V and a capacitance of 220 μF (size: diameter 10 mm × height 10 mm) ) Was produced.

  The shape of the sealing body is 10 mm in diameter and 4 mm in thickness, and each side surface is formed with an annular recess having a radius of curvature of 5, 10, 15, and 20 mm. Drawing was performed so that the drawn portion of the metal case was aligned with the annular recess formed in the portion.

(Example 2)
In the first embodiment, a chip was formed in the same manner as in the first embodiment except that a chip type aluminum electrolytic capacitor (size: diameter 4 mm × height 5.8 mm) having a rated voltage of 35 V and a capacitance of 4.7 μF was used. Type aluminum electrolytic capacitors were produced.

  The shape of the sealing body is 4 mm in diameter and 2 mm in thickness, and an annular recess having a radius of curvature of 2 mm is formed on its side surface, and the metal case is drawn by an annular recess formed on the side surface of the sealing body. The metal case was drawn so that the drawn portion of the metal case was along.

(Example 3)
In Example 1, instead of the driving electrolyte, the capacitor element contains 1 part of ethylenedioxythiophene as a heterocyclic monomer and 31.0% by weight of ferric p-toluenesulfonate as an oxidizing agent. A solid electrolyte layer of polyethylenedioxythiophene, which is a conductive polymer, is electrode foil by dipping in a polymerizable mixed solution containing 6 parts of an oxidant solution of 6 parts of n-butanol solution and then leaving it at 85 ° C. for 60 minutes. A chip-type aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that it was formed in between.

(Comparative Example 1)
A chip-type aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that a sealing body having a diameter of 10 mm and a thickness of 4 mm (no annular recess) was used.

(Comparative Example 2)
A chip-type aluminum electrolytic capacitor was produced in the same manner as in Example 2 except that a sealing body having a diameter of 4 mm and a thickness of 2 mm (no annular recess) was used.

  About the chip-type aluminum electrolytic capacitors of Examples 1 to 3 and Comparative Examples 1 and 2 described above, 20 samples were prepared and subjected to a life test. The results are shown in (Table 1). The life test was a ripple load test at a test temperature of 105 ° C.

  As apparent from (Table 1), the chip-type aluminum electrolytic capacitors of Examples 1 to 3 have an annular recess formed in the side surface portion of the sealing body, and are drawn into the annular recess when being drawn from the outside of the metal case. By forming the drawn portion so as to follow, a chip-type aluminum electrolytic capacitor excellent in the life test can be obtained.

  Further, by using a conductive polymer solid electrolyte instead of the driving electrolyte, further excellent capacitor characteristics and life characteristics can be obtained.

  The aluminum electrolytic capacitor according to the present invention has a feature that it can improve the reliability of life with a simple configuration and can be manufactured without applying stress to the capacitor element, and is useful as a chip-type aluminum electrolytic capacitor that requires reliability. It is.

Sectional drawing which shows the structure of the chip-type aluminum electrolytic capacitor in one embodiment of this invention Perspective view of the enclosed body Sectional view showing the configuration of a conventional chip-type aluminum electrolytic capacitor Sectional view showing the configuration of a chip-type aluminum electrolytic capacitor after the same life test

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Capacitor element 12 Anode lead 13 Cathode lead 14 Sealing body 15 Annular recess of sealing body 16 Through hole 17 Metal case 18 Drawing part of metal case 19 Insulating seat plate

Claims (3)

A capacitor element in which an anode foil connected to an anode lead and a cathode foil connected to a cathode lead are wound together with a separator, a driving electrolyte impregnated in the capacitor element, and a bottomed cylindrical metal containing the capacitor element A case and a sealing body that seals the opening of the metal case, an annular recess is provided on a side surface of the sealing body, and a protrusion that is drawn from the outside of the metal case follows the shape of the annular recess. Chip-type aluminum electrolytic capacitor. The chip-type aluminum electrolytic capacitor according to claim 1, wherein an annular recess provided on a side surface of the sealing body has an R shape. The chip-type aluminum electrolytic capacitor according to claim 1 or 2, wherein a conductive polymer is used as an electrolyte instead of the driving electrolyte.

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