JP2001110693A - Aluminum electrolytic capacitor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely seal a case opening with a thermosetting resin, without causing transpiration of an electrolyte. SOLUTION: An aluminum foil wound-type capacitor element 13 is housed in a cylindrical case 11 with a bottom. A sealing sheet 16 is disposed on the capacitor element 13. An intermediate sealing layer 17 composed of a UV-curing resin is formed on the sealing sheet 16 for temporary sealing. Then, an outer sealing layer 18 composed of a thermosetting resin is further formed on the intermediate sealing layer 17 for final sealing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum electrolytic capacitor and a method for manufacturing the same, and more particularly, to an improvement in sealing means for the same.

[0002]

2. Description of the Related Art An aluminum electrolytic capacitor is constructed by housing a capacitor element of a rolled type aluminum foil impregnated with an electrolytic solution in a cylindrical case having a bottom and closing an opening of the case. In this case, the sealing is performed exclusively for the purpose of preventing the evaporation of the electrolyte.

[0003] The most well-known sealing method is a method of fitting a sealing rubber made of, for example, butyl rubber into an opening of a case. In this sealing method, a so-called lateral drawing groove is formed along the circumferential direction on the outer peripheral surface side of the case after the sealing rubber is fitted, in order to prevent the sealing rubber from coming off and enhance airtightness, and to open the case. The edges are curled inward.

Therefore, the sealing method using the sealing rubber is limited to a case having a cylindrical shape, and cannot be applied to a rectangular cylindrical case in which formation of a horizontal drawing groove or curling is difficult. Therefore, in the case of a rectangular cylindrical case, another sealing method has been proposed, one example of which is disclosed in JP-A-56-83001.

The sealing method will be described with reference to FIG. 5. A sealing plate 3 for sealing a rectangular case 2 in which a component element 1 is stored.
A laminate in which a support layer 3c such as a foamed sheet is joined to a thermosetting resin layer 3a which is temporarily melted and fluidized at the time of heat processing and then hardened via an adhesive layer 3b co-reactive with the resin layer 3a. Use the body.

The thermosetting resin layer 3a is made of, for example, a phenol resin or epoxy resin resin. According to this, after the sealing plate 3 is fitted into the opening of the square case 2,
By heating to a predetermined temperature, the sealing is performed. That is, when the temperature reaches a certain temperature, the thermosetting resin layer 3a is melted and fused to the case 2, and by further raising the temperature, the thermosetting resin layer 3a is cured while being fused to the case 2.

[0007]

However, there are the following problems in applying this sealing method using a thermosetting resin to, for example, a square (square cylindrical) aluminum electrolytic capacitor.

That is, for example, an epoxy resin which is a thermosetting resin is not completely cured unless a high temperature (for example, about 120 ° C., about 30 minutes) is applied for a predetermined time. In the case of an aluminum electrolytic capacitor, since a capacitor element impregnated with an electrolytic solution is housed in the case, the electrolytic solution evaporates before the thermosetting resin is cured.
The same can be said for the cylindrical aluminum electrolytic capacitor as well as the prismatic type.

As a means for sealing a rectangular aluminum electrolytic capacitor, there is a rubber-clad laminate provided with lug terminals, which is used exclusively for large-sized capacitors. Small capacitors that are directly drawn out have structural and
It is not preferable in terms of cost.

[0010]

According to the present invention, such a problem is solved, and the opening of the case can be sealed with a thermosetting resin without causing evaporation of the electrolytic solution. An aluminum electrolytic capacitor is obtained.

That is, the present invention comprises an aluminum foil wound capacitor element, a bottomed cylindrical case in which the capacitor element is housed, and sealing means for sealing the opening of the case. In an aluminum electrolytic capacitor in which a pair of lead terminals attached to the capacitor element is drawn out of the case through the sealing means, the sealing means is disposed on the capacitor element side in the opening. A sheet, a sealing intermediate layer formed of an ultraviolet curable resin formed on the sealing sheet, and a laminated body having a sealing outer layer formed of a thermosetting resin formed on the sealing intermediate layer, I have.

It is not necessary to raise the temperature to cure the ultraviolet-curable resin. Therefore, at a temperature near normal temperature,
The sealing intermediate layer can be formed without almost evaporating the electrolyte, and can be preliminarily sealed. Therefore, the evaporation of the electrolytic solution when the sealing outer layer is formed by the thermosetting resin is effectively prevented.

In the present invention, since there is no need to form a horizontal drawing groove in the case, a rectangular cylindrical case can be used as the case. Of course, it may be cylindrical. In the case of a cylindrical shape, the opening edge of the case may be curled inward. When the case is in the shape of a rectangular tube, the opening edge thereof may be bent at a substantially right angle inward.

The case may be made of a synthetic resin other than a metal represented by aluminum. As the resin, heat-resistant polyphenylene sulfide (PP
S), a liquid crystal polymer (LCP) or Amodel is preferably exemplified. Further, the sealing sheet is preferably a fluorine-based resin, which may be plate-shaped.

In the present invention, it is preferable that at least the inner surface of the case opening which is in contact with the outer layer of the sealing is roughened by unevenness, whereby the adhesion between the sealing means and the case is improved. it can.

The present invention includes the following three manufacturing methods. That is, the first manufacturing method of the present invention includes a first step of housing an aluminum foil wound capacitor element to which a pair of lead terminals are attached in a bottomed cylindrical case and injecting a predetermined electrolytic solution. A second step of inserting a sealing sheet into the opening of the case while penetrating the lead terminal, and injecting an ultraviolet curable resin onto the sealing sheet in the opening,
Third to cure by ultraviolet irradiation to form a sealing intermediate layer
And a fourth step of injecting a thermosetting resin onto the sealing intermediate layer and curing the same by heating to form a sealing outer layer, whereby the evaporation of the electrolytic solution is caused. Without this, the case opening can be sealed with a thermosetting resin, and the above object is achieved.

A second manufacturing method according to the present invention includes a first step of accommodating a pair of lead terminals and accommodating an aluminum foil wound capacitor element impregnated with an electrolytic solution in a bottomed cylindrical case. A second step of inserting a sealing sheet into the opening of the case while penetrating the lead terminal, and injecting an ultraviolet curable resin onto the sealing sheet in the opening and curing the resin by irradiation with ultraviolet light to form a sealing intermediate layer And a fourth step of injecting a thermosetting resin onto the sealing intermediate layer and curing it by heating to form an outer sealing layer. Thus, the case opening can be sealed with the thermosetting resin without inviting the above, and the above object is achieved.

A third manufacturing method according to the present invention is directed to a bottomed cylinder having a pair of lead terminals attached thereto, and an aluminum foil-wound capacitor element impregnated with an electrolyte with a sealing sheet attached to the lead terminals. A first step of accommodating an ultraviolet-curable resin on the sealing sheet in the opening, and a second step of curing the resin by irradiation with ultraviolet light to form a sealing intermediate layer; And a third step of forming a sealing outer layer by injecting a thermosetting resin and curing by heating, whereby the case opening can be thermoset without causing evaporation of the electrolytic solution. Can be sealed with a conductive resin, thereby achieving the above object.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention will be described with reference to an exploded perspective view of FIG. 1 and a sectional view of FIG. 1 and 2 are upside down.

The first embodiment is of a rectangular tube type. This aluminum electrolytic capacitor 10 includes a bottomed rectangular tube-shaped case 11, a capacitor element 13, and a sealing means 15. In this case, the case 11 is made of aluminum, and a flange 111 as a bending allowance is continuously provided on an opening edge of each case on each side. Each of the flanges 111 is formed in a trapezoidal shape so that their ends do not overlap when bent toward the inside of the case.

Although not shown in detail, the capacitor element 13 is formed by spirally winding an anode electrode foil and a cathode electrode foil both made of aluminum via a separator. Tab terminal type lead terminals 131 are fixed to each electrode foil by welding or swaging.

In this embodiment, the capacitor element 13
Is formed in a rectangular cylindrical shape so that almost no gap is formed in the case 11. Note that the capacitor element 13
May be cylindrical. After housing the capacitor element 13, a predetermined electrolytic solution is injected into the case 11.

Alternatively, the capacitor element 13 may be impregnated with an electrolytic solution in advance and stored in the case 11. In order to form the capacitor element 13 into a rectangular tube shape, it may be wound into a cylindrical shape and then formed into a square shape by pressing or the like, or may be wound around a prismatic core material.

The sealing means 15 comprises a laminate of a sealing sheet 16, a sealing intermediate layer 17, and a sealing outer layer 18. The sealing sheet 16 is preferably made of a fluorine-based resin, and includes a plate-like body. The sealing intermediate layer 17 is made of an ultraviolet curable resin, and the sealing outer layer 18 is made of a thermosetting resin. In this embodiment, an epoxy resin is used.

Although not shown, at least the inner surface of the case 11 which is in contact with the outer sealing layer 18 is subjected to a satin finish so as to have a rough surface having fine irregularities. This rough surface can be formed by, for example, sandblasting or chemical etching. Case 11 is made of heat-resistant polyphenylene sulfide (PPS), liquid crystal polymer (L
It may be made of a synthetic resin such as CP) or Amodel.

The present invention can also be applied to a cylindrical aluminum electrolytic capacitor, an example of which is shown in FIG. 3 as a second embodiment. That is, the case 11A of the aluminum electrolytic capacitor 10A has a cylindrical shape with a bottom, and accordingly, the capacitor element 13A and the sealing means 15A are also formed in a cylindrical shape and a circular shape.

Also in the second embodiment, the case 11A
May be made of metal or synthetic resin. Even when the case 11A is made of metal, the lateral drawing groove is unnecessary. However, the opening edge of the case 11A can be curled inward as in the second embodiment.

Next, the manufacturing method of the present invention will be described with reference to FIG. In FIG. 4, (a), (b)
1), (c1) and (d1) are production examples of the rectangular cylindrical aluminum electrolytic capacitor of the first embodiment, and FIGS. (A), (b2), (c2) and (d2) show the second embodiment. It is a manufacture example about the cylindrical aluminum electrolytic capacitor of an example. Both cases are made of aluminum, and a rough surface made of fine irregularities is formed on the inner surface on the opening side.

The first step shown in FIG. 4A is common to the square tube type and the cylindrical type. That is, in the case of the rectangular tube type, the capacitor element 13 formed in a rectangular tube shape is housed in the case 11 having a bottomed rectangular tube shape, and a predetermined electrolytic solution is injected into the case 11. In the case of a cylindrical type, the cylindrical capacitor element 13A is housed in the bottomed cylindrical case 11A, and a predetermined electrolytic solution is injected into the case 11A. Alternatively, the capacitor element 13 previously impregnated with the electrolytic solution may be housed in the case 11 as described above.

After that, the sealing sheet 16 (16A) is placed on the capacitor element 13 (13A). As shown in FIG. 1, lead insertion holes 161 and 161 for inserting the lead terminals 131 and 131 are formed in the sealing sheet 16 (16A) in advance.

The sealing sheet 16 (16A) is filled with an ultraviolet curable resin 17a so as to have a predetermined thickness, and is cured by irradiating ultraviolet rays. Sealing sheet 16 (1
6A) is for preventing the ultraviolet curable resin 17a from dripping. The ultraviolet curable resin 17a has an output of, for example, 1.0 to
3-5 UV rays by 1.5 kW spot UV irradiator
It can be cured by irradiation for about seconds. In particular, since there is no need to raise the temperature, evaporation of the electrolytic solution hardly occurs.

In this way, as shown in FIGS. 4 (b1) and 4 (b2), the sealing intermediate layers 17, 17A made of ultraviolet curable resin are formed for both the square tube type and the cylindrical type. The sealing intermediate layers 17, 17A function as a temporary (preliminary) sealing material.

Next, as shown in FIG. 4 (b1), the sealing intermediate layer 17 is filled with an epoxy resin 18a as a thermosetting resin so as to have a predetermined thickness.
It is cured by heating, and the main sealing is performed.

To cure the epoxy resin, for example,
Although the case is exposed to a high temperature of 20 ° C. for about 30 minutes, since the case opening is sealed with the sealing intermediate layer 17, there is no possibility that the electrolytic solution evaporates.

As a result, as shown in FIG.
The outer sealing layer 18 is formed on the sealing intermediate layer 17 (final sealing). In this example, since the inner surface of the case 11 is roughened, the adhesion between the outer sealing layer 18 and the case 11 is enhanced. And finally, as shown in FIG. 4 (d1),
The flange 111 formed on each side of the case 11 is bent inward. This bending step is optional and not an essential step in the present invention.

On the other hand, for the cylindrical type, the sealing intermediate layer 17
After the formation of A, as shown in FIG.
After curling the opening edge toward the inside,
As shown in (c2), an epoxy resin 18a as a thermosetting resin is filled on the sealing intermediate layer 17A so as to have a predetermined thickness, and is cured by heating. The heat-curing conditions are the same as those of the square tube type.

In this way, as shown in FIG. 4 (d2), a sealing outer layer 18A is finally formed on the sealing intermediate layer 17A. The curl processing performed in the step of FIG. 4 (b2) is for preventing the epoxy resin 18a from scattering outside the case. If there is no possibility of such a curl processing, it is not necessary to perform the curl processing.

[0038]

Example 1 An aluminum foil-wound capacitor element was housed in a square aluminum case having a side length of 8 mm and a shaft length of 8 mm, and an electrolyte was injected into the case. After disposing a 0.2 mm thick sealing sheet made of tetrafluoroethylene, a 1.0 mm thick sealing intermediate layer made of an ultraviolet curable resin and a 1.5 mm thick sealing outer layer made of an epoxy resin are placed thereon. And the case opening was sealed. In this way, 50 rectangular aluminum electrolytic capacitors were manufactured, and 105
When a reliability test was performed at ℃ / 2000 hours, no liquid leakage was observed for all of the 50 test pieces.

Example 2 A case having a diameter of 8 mm was used.
Except for using a cylindrical aluminum case having an axial length of 8 mm, 50 cylindrical aluminum electrolytic capacitors were manufactured and subjected to a reliability test at 105 ° C./2000 hours in the same manner as in Example 1 above. No liquid leakage was observed for all 50 pieces.

<Comparative Example 1> An attempt was made to seal the square aluminum case of Example 1 with a sealing rubber made of butyl rubber, but the sealing was difficult.

<Comparative Example 2> Japanese Patent Laid-Open Publication No. Sho 5 discloses a case in which the square quadrangular aluminum case of the above-mentioned Embodiment 1 is used as a conventional example.
No. 6,831,001, but the capacitor characteristics (initial value) were too poor to be commercialized.

Comparative Example 3 A sealing rubber made of butyl rubber was fitted into the opening of the cylindrical aluminum case of Example 2 to form a horizontal drawing groove on the outer peripheral surface of the case. The edges were curled and sealed. For these 50 pieces, 105 ° C./20 as in Example 1 above.
When the reliability test was performed for 00 hours, 3 out of 50
Liquid leakage was observed for each individual.

[0043]

According to the present invention, the following effects can be obtained. That is, after the case opening is sealed with an ultraviolet curable resin, the main opening is sealed with a thermosetting resin, so that the case opening is made of a thermosetting resin without causing evaporation of the electrolytic solution. It can be sealed securely.

Therefore, a horizontal drawing groove for sealing is not required, and it is possible to efficiently produce the material as compared with the conventional sealing rubber, and to reduce the height by using the same capacitance. In addition, a rectangular aluminum electrolytic capacitor can also be of a rectangular tube type.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of an aluminum electrolytic capacitor according to the present invention.

FIG. 2 is a sectional view of the first embodiment.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is an explanatory view showing a manufacturing method of the present invention.

FIG. 5 is an exploded perspective view showing a conventional example.

[Explanation of symbols]

 10, 10A Aluminum electrolytic capacitor 11, 11A Case 13, 13A Capacitor element 131 Lead terminal 15, 15A Sealing means 16, 16A Sealing sheet 161 Lead insertion hole 17, 17A Sealing intermediate layer 18, 18A Sealing outer layer

Claims (15)

[Claims] An aluminum foil-wound capacitor element, a bottomed cylindrical case in which the capacitor element is housed, and sealing means for sealing an opening of the case. An aluminum electrolytic capacitor in which a pair of attached lead terminals is drawn out of the case through the sealing means, wherein the sealing means is the same as a sealing sheet arranged on the capacitor element side in the opening. An aluminum electrolytic capacitor comprising a laminate having a sealing intermediate layer formed of an ultraviolet-curable resin formed on a sealing sheet, and a sealing outer layer formed of a thermosetting resin formed on the sealing intermediate layer. . 2. The aluminum electrolytic capacitor according to claim 1, wherein said case has a cylindrical shape without a lateral drawing groove. 3. The aluminum electrolytic capacitor according to claim 2, wherein the opening edge of the case is curled inward. 4. The aluminum electrolytic capacitor according to claim 1, wherein said case has a rectangular tube shape. 5. The aluminum electrolytic capacitor according to claim 4, wherein an opening edge of the case is bent substantially inward toward the inside. 6. The aluminum electrolytic capacitor according to claim 1, wherein said case is made of metal. 7. The aluminum electrolytic capacitor according to claim 1, wherein said case is made of a synthetic resin. 8. The aluminum electrolytic capacitor according to claim 1, wherein said sealing sheet is made of a fluorine resin. 9. The aluminum electrolytic capacitor according to claim 1, wherein at least an inner surface of said opening portion in contact with said outer sealing layer is roughened by unevenness. 10. A first step in which an aluminum foil wound capacitor element to which a pair of lead terminals is attached is housed in a bottomed cylindrical case and a predetermined electrolytic solution is injected, and a sealing sheet is attached to the lead terminal. A second step of inserting into the opening of the case while penetrating the case, and a third step of injecting an ultraviolet curable resin onto the sealing sheet in the opening and curing the resin by irradiation with ultraviolet light to form a sealing intermediate layer; Performing a fourth step of injecting a thermosetting resin onto the sealing intermediate layer and curing the same by heating to form an outer sealing layer. 11. A first step in which a pair of lead terminals are attached and an aluminum foil wound capacitor element impregnated with an electrolytic solution is housed in a bottomed cylindrical case, and a sealing sheet is passed through the lead terminals. A second step of inserting a UV curable resin into the opening sheet of the case while injecting the resin into the sealing sheet in the opening, and curing the resin by irradiation with UV light to form a sealing intermediate layer; A fourth step of injecting a thermosetting resin onto the intermediate layer and curing it by heating to form an outer sealing layer. 12. A method of accommodating a pair of lead terminals and accommodating an aluminum foil wound capacitor element impregnated with an electrolyte in a bottomed cylindrical case with a sealing sheet attached to the lead terminal portion. One step, and a second step of injecting an ultraviolet curable resin onto the sealing sheet in the opening and curing the resin by ultraviolet irradiation to form a sealing intermediate layer;
A step of injecting a thermosetting resin onto the sealing intermediate layer and curing the same by heating to form a sealing outer layer. 13. The method for manufacturing an aluminum electrolytic capacitor according to claim 10, wherein a case in which at least an inner surface of an opening portion in contact with the outer sealing layer is roughened is used as the case. 14. In the case where the case is a metal cylinder, a step of curling the opening edge of the case inward after forming the sealing intermediate layer and before forming the sealing outer layer is further performed. , 11 or 12. 15. In the case where the case is made of a metal and is a rectangular cylinder, a step of bending the opening edge of the case inward at a substantially right angle after forming the outer sealing layer is further performed. 3. The method for producing an aluminum electrolytic capacitor according to item 1.