JP2012044068A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor which suppresses the evaporation of an electrolytic solution and enhances fracture strength of a sealing body.SOLUTION: An electrolytic capacitor includes a capacitor element 7 formed by overlapping a valve metal anode foil 1 on a valve metal cathode foil 2 with a sheet of electrolytic paper sandwiched therebetween and rolling up the overlapped anode foil 1 and the cathode foil 2, a cup shaped exterior case 12 housing the capacitor element 7, and a sealing body 20 sealing an opening of the exterior case 12. An elastic body in which scale like glass is mixed is used as the sealing body 20.

Description

  The present invention relates to an electrolytic capacitor.

  An electrolytic capacitor uses a metal called valve metal such as aluminum, tantalum, and niobium as an electrode, and uses an oxide film layer obtained by anodizing as a dielectric.

  An aluminum electrolytic capacitor using aluminum as an electrode has an anode foil and a cathode foil that have been subjected to an etching process and an oxide film forming process wound around a separator and fixed by an element stopper tape to form a capacitor element. Yes. The capacitor element is impregnated with a driving electrolyte solution, and then stored in a bottomed cylindrical outer case, and in some cases, is fixed in the case using a fixing material.

  Further, a sealing body is attached to the opening of the exterior case, and the opening is configured to be sealed by drawing.

  The substrate self-supporting type aluminum electrolytic capacitor has an anode terminal and a cathode terminal formed on the outer end surface of the sealing body, and the anode tab terminal and the cathode tab terminal drawn out from the capacitor element are electrically connected to the ends of these terminals. It is connected. Further, in the lead wire type aluminum electrolytic capacitor, the lead terminal electrically connected to the anode tab terminal and the cathode tab terminal drawn out from the capacitor element is drawn to the outside through the insertion hole provided in the sealing body. .

  By the way, in the conventional electrolytic capacitor, there existed a problem that a lifetime became short because electrolyte solution evaporated from a sealing body.

  One measure for solving this problem is to improve the airtightness by mixing glass fiber or inorganic powder base material with phenol resin used for the sealing plate (see Patent Document 1), talc or The thing using the rubber material which added mica as a sealing board is considered (refer patent document 2 and patent document 3).

JP 2005-721159 A JP-A-55-55514 JP 2008-251980 A

  Further, in the electrolytic capacitor, a pressure valve is provided at the bottom of the bottomed cylindrical outer case, and the pressure valve is operated as the internal pressure rises to release the internal pressure to the outside. . By improving the breaking strength of the sealing body so as to correspond to the operating pressure at which this pressure valve operates, the pressure valve operates before the sealing body breaks.

  Thus, since it is necessary to improve the breaking strength of the sealing body so as to correspond to the operating pressure of the pressure valve, if the breaking strength of the sealing body can be increased, the operating pressure of the pressure valve can be increased. it is conceivable that.

  An object of this invention is to provide the electrolytic capacitor which can suppress the evaporation of electrolyte solution and can raise the breaking strength of a sealing body.

  The electrolytic capacitor of the present invention includes a capacitor element formed by stacking and winding a valve metal anode foil and a cathode foil through a separator, a bottomed cylindrical outer case for housing the capacitor element, and the outer case An electrolytic capacitor provided with a sealing body that seals the opening of the above, wherein an elastic body mixed with scaly glass is used as the sealing body.

  According to this configuration, by using a rubber material mixed with glass flakes for the sealing body, the gas permeation amount of the sealing body can be reduced, and the breaking strength is also improved in the sealing body of the large capacitor. be able to.

  In the electrolytic capacitor of the present invention, the elastic body has at least 0.5 weight of the glass flake powder having an average thickness of 0.4 to 5.0 μm and an average particle diameter of 10 to 900 μm. % Mixture.

  According to this configuration, by using an elastic body in which at least 0.5% by weight of scaly glass having a predetermined average thickness and a predetermined average particle diameter is used, the gas permeation amount is reduced and the sealing body of the large capacitor is used. It is possible to effectively improve the breaking strength.

  Moreover, the electrolytic capacitor of the present invention is characterized in that, in the above configuration, the sealing body is a resin plate to which the elastic body mixed with the glass flakes is attached.

  According to this configuration, it is possible to easily reduce the gas permeation amount and improve the breaking strength of the sealing body of the large capacitor by simply attaching the rubber material mixed with the glass flakes to the phenol resin plate.

  According to the electrolytic capacitor of the present invention, it is possible to provide an electrolytic capacitor capable of suppressing the evaporation of the electrolytic solution and increasing the breaking strength in the sealing body of the large capacitor.

It is a disassembled perspective view of the capacitor | condenser element used with the electrolytic capacitor of this invention. It is sectional drawing which shows the structure of the electrolytic capacitor of this invention. It is a flowchart which shows the manufacturing process of the electrolytic capacitor of this invention. It is a top view which shows the pressure valve provided in the bottom face part of the exterior case of the electrolytic capacitor of this invention. It is a graph which shows the result of the gas permeability test of the electrolytic capacitor using the sealing board of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a capacitor element of the electrolytic capacitor according to the present embodiment, and FIG. 2 is a cross-sectional view showing the configuration of the electrolytic capacitor. As shown in FIG. 1, in an electrolytic capacitor, an anode foil 1 and a cathode foil 2 that have been subjected to an etching process and an oxide film formation process are wound through an electrolytic paper (separator) 3, and an element stopper tape 6 is used. A capacitor element 7 is formed by being fixed. The capacitor element 7 is impregnated with a driving electrolyte, and then stored in a bottomed cylindrical outer case 12 (FIG. 2) and fixed by a fixing material 14 (FIG. 2) made of polypropylene or tar pitch. .

  A sealing plate 20 is attached to the opening of the outer case 12 as a sealing member, and the opening is sealed by drawing. The sealing plate 20 includes a phenol resin plate 21 and a rubber material 22 attached to the phenol resin plate 21. The rubber material 22 is provided on the entire surface of the phenol resin plate 21 outside the electrolytic capacitor by adhesion. The rubber material 22 is mixed with at least 0.5% by weight or more of scaly glass having an average thickness of 0.4 to 5.0 μm and an average particle diameter of 10 to 900 μm.

  An anode terminal 8 and a cathode terminal 9 are formed on the outer end surface of the sealing plate 20, and an anode lead lead 4 and a cathode lead lead 5 drawn from the capacitor element 7 are crimped at the ends of these terminals 8 and 9. They are electrically connected via the parts (or welds) 13A and 13B.

  Here, the anode lead 4 is subjected to a chemical conversion treatment, but the cathode lead 5 is generally not subjected to a chemical conversion treatment. For any of the lead leads (the anode lead lead 4 and the cathode lead lead 5), a valve metal foil that is not subjected to surface processing is generally used.

  Further, the sealing of the substrate self-supporting type electrolytic capacitor is made by the rubber material of the sealing plate 20 and the portion where the outer case 12 is curled.

  As described above, the sealing plate 20 used in the electrolytic capacitor according to the present embodiment is obtained by attaching the rubber material 22 mixed with the glass flakes to the phenol resin plate 21. A breaking strength test was performed on the sealing plate 20 to which the rubber material 22 formed by mixing powder of glass flakes having a predetermined average thickness and a predetermined average particle diameter was attached. The sealing plate 20 used for this breaking strength test is a sealing plate used for an electrolytic capacitor having a diameter of 35 mm. In addition, an electrolytic capacitor having a rating of 50 V, 15000 μF, a diameter of 35 mm, and a length of 50 mm was produced using the sealing plate 20, and a gas permeability test was performed. These test results will be described later.

  Next, a method for manufacturing the electrolytic capacitor of the present embodiment will be described. FIG. 3 is a flowchart showing manufacturing steps of the electrolytic capacitor according to the present embodiment.

(Etching process)
In an etching solution (strongly acidic aqueous solution such as hydrochloric acid), the surface of the aluminum foil is made uneven by electrochemically applying a DC voltage or an AC voltage to increase the surface area (step S101).

(Chemical conversion process)
A DC voltage is applied in a chemical conversion solution (weakly acidic aqueous solution such as ammonium borate) to form an aluminum oxide film serving as a dielectric on the surface of the etching foil (step S102).

(Casting and winding process)
The electrode lead material is connected to each of the anode foil and the cathode foil while being wound around the cylindrical capacitor element 7 via the electrolytic paper 3 shown in FIG. 1 between the two electrode foils. Stop with the tape 6 (step S103). Examples of the connection method between the electrode lead material and the electrode foil include a needle hole crimping method and cold crimping (cold crimping).

(Impregnation process)
Capacitor element 7 is impregnated with the driving electrolyte by reducing pressure or increasing pressure (step S104). The impregnation time at this time varies depending on the size of the capacitor element 7 and the type of the driving electrolyte, but generally the larger the element size, the longer the impregnation time. Thereafter, a certain amount of excess driving electrolyte is removed by a centrifuge.

(Assembly process)
After the capacitor element 7 impregnated with the driving electrolyte and the sealing plate 20 (the phenol resin plate 21 with the rubber material 22 attached) are joined, the fixing material 14 is poured into the outer case 12. Immediately after that, the capacitor element 7 to which the sealing plate 20 is bonded is inserted into the outer case 12 and sealed to keep hermetic (step S105). The sealing plate 20 can be obtained by a simple method of simply sticking the rubber material 22 mixed with the glass flakes to the phenol resin plate 21.

(Aging process)
A DC voltage is applied to the electrolytic capacitor (product) at a high temperature to repair the oxide film damaged by cutting or winding the foil (step S106).

  The present invention will be described more specifically with reference to the following examples.

  First, the breaking strength test of the sealing plate 20 will be described. In this breaking strength test, a sealing plate 20 in which a rubber material 22 was bonded to a phenol resin plate 21 with an adhesive was produced. The size of the sealing plate 20 is a size used for an electrolytic capacitor having a diameter of 35 mm.

Example 1
Example 1 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 0.4 μm and an average particle size of 10 μm is mixed at a ratio of 0.5 wt% is attached to a phenol resin plate 21. It is.

(Example 2)
Example 2 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 0.4 μm and an average particle size of 10 μm is mixed at a ratio of 5.0% by weight is bonded to a phenol resin plate 21. It is.

(Example 3)
Example 3 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 0.4 μm and an average particle size of 10 μm is mixed at a ratio of 10.0% by weight is attached to a phenol resin plate 21. It is.

Example 4
Example 4 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 5.0 μm and an average particle size of 10 μm is mixed at a ratio of 0.5% by weight is attached to a phenol resin plate 21. It is.

(Example 5)
Example 5 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 5.0 μm and an average particle size of 10 μm is mixed at a ratio of 10.0% by weight is attached to a phenol resin plate 21. It is.

(Example 6)
Example 6 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 0.4 μm and an average particle size of 900 μm is mixed at a ratio of 0.5% by weight is attached to a phenol resin plate 21. It is.

(Example 7)
Example 7 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 0.4 μm and an average particle size of 900 μm is mixed at a ratio of 10.0% by weight is attached to a phenol resin plate 21. It is.

(Example 8)
Example 8 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 5.0 μm and an average particle size of 900 μm is mixed at a ratio of 0.5% by weight is attached to a phenol resin plate 21. It is.

Example 9
Example 9 is a sealing plate 20 in which a rubber material 22 in which a scale-like glass powder having an average thickness of 5.0 μm and an average particle size of 900 μm is mixed at a ratio of 10.0% by weight is attached to a phenol resin plate 21. It is.

(Example 10)
Example 10 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 0.1 μm and an average particle size of 900 μm is mixed in a proportion of 10.0% by weight is attached to a phenol resin plate 21. It is.

(Example 11)
Example 11 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 5.5 μm and an average particle size of 900 μm is mixed at a ratio of 10.0% by weight is attached to a phenol resin plate 21. It is.

(Example 12)
Example 12 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 5.0 μm and an average particle size of 5 μm is mixed at a ratio of 10.0% by weight is attached to a phenol resin plate 21. It is.

(Example 13)
Example 13 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 5.0 μm and an average particle size of 1000 μm is mixed at a ratio of 10.0% by weight is attached to a phenol resin plate 21. It is.

(Conventional example)
A conventional example is a sealing plate formed by sticking a rubber material not mixed with powder of glass flakes to a phenolic resin plate.

  The breaking strength test and the rubber hardness were measured for the sealing plate 20 of Examples 1 to 13 and the sealing plate of the conventional example. The breaking strength test is a test in which a sealing plate is attached to a hydraulic testing machine and the pressure when the sealing plate is broken is measured. The rubber hardness was measured according to JIS K6253. The measurement results are shown in Table 1.

  Table 1 shows the following. When the sealing plate 20 using the rubber material 22 mixed with the glass flake powder of Examples 1 to 13 of the present invention is compared with the sealing plate of the conventional example using the rubber material not mixing the glass flake powder, Rubber hardness and breaking strength are improved. Thus, the rubber hardness was improved by mixing the scaly glass with the rubber material 22, and the breaking strength of the sealing plate 20 was improved.

  Thus, from Table 1, the sealing plate 20 formed by adhering the rubber material 22 mixed with the glass flake powder at a ratio of at least 0.5% by weight to the phenol resin plate 21 is mixed with the glass flake powder. The breaking strength can be improved as compared with a sealing plate formed by attaching a rubber material that is not bonded to the phenol resin plate 21. In the electrolytic capacitor using the sealing plate 20, the occurrence of warpage of the sealing plate 20 can be reduced by increasing the internal pressure.

  Further, as shown in FIG. 4, a pressure valve 15 is provided on the bottom surface portion 12 </ b> A (FIG. 2) of the outer case 12 for the purpose of releasing the gas generated suddenly in the electrolytic capacitor. The pressure valve 15 is formed by forming a thin portion in a cross shape on the bottom surface portion 12A of the outer case 12, so that the thin portion is broken as the internal pressure rises, and the internal pressure is released to the outside. The internal pressure when the valve is opened is called the valve operating pressure, and it is necessary to improve the breaking strength of the sealing plate 20 so as to be able to cope with this operating pressure. According to the present invention, since the breaking strength of the sealing plate 20 can be improved, the valve operating pressure of the exterior case 12 can be increased accordingly.

  Next, the gas permeability test will be described. After superposing the anode foil 1 and the cathode foil 2 with the electrolytic paper 3 and impregnating the wound substrate self-supporting type electrolytic capacitor element 7 with the driving electrolytic solution, the excess driving electrolytic solution is removed by a centrifuge. remove. The capacitor element 7 was inserted into the outer case 12 together with the sealing plate 20 and fixed by the fixing material 14 to produce an electrolytic capacitor having a rating of 50 V, 15000 μF, a diameter of 35 mm, and a length of 50 mm.

(Example 14)
Example 14 is a sealing plate 20 in which a rubber material 22 in which a glass flake powder having an average thickness of 0.4 μm and an average particle size of 160 μm is mixed at a ratio of 0.5 wt% is attached to a phenol resin plate 21. This is an electrolytic capacitor using

  A gas permeability test was performed on the electrolytic capacitors of Examples 1 and 14 and the electrolytic capacitor of the conventional example. The gas permeability test is to examine the amount of transpiration of internal gas over time (permeation amount of internal gas permeating through the sealing plate 20) when the electrolytic capacitor is left in an environment of 115 ° C. In this gas permeability test, the change in the weight of the electrolytic capacitor is measured, and this measurement result is used as the amount of decrease in the electrolytic solution. The measurement results are shown in the graph (FIG. 5).

  FIG. 5 shows the weight of the electrolytic capacitor over time (0 to 500 hours [H]) when the electrolytic capacitors of Examples 1 and 14 and the conventional example are left in an environment of a predetermined temperature (115 [° C.]). It is a graph which shows the measurement result of a change (deltag / g [%]).

  As shown in FIG. 5, the electrolytic capacitors of Examples 1 and 14 of the present invention have a smaller change in the weight of the electrolytic capacitor over time as compared with the electrolytic capacitor of the conventional example. This means that there is little decrease in the electrolyte solution. From this measurement result, the sealing plate 20 used in the electrolytic capacitors of Examples 1 and 14 (the rubber material 22 mixed with the glass flakes) was used. It can be seen that the gas permeation amount of the sealing plate affixed to the phenol resin plate 21 is small.

  That is, it can be seen that the gas permeation amount is small in the sealing plate 20 in which the rubber material 22 formed by mixing the glass flake powder at a ratio of at least 0.5 wt% is attached to the phenol resin plate 21. By using the sealing plate 20 with a small amount of gas permeation, transpiration of the electrolytic solution can be suppressed, and the life of the electrolytic capacitor can be extended accordingly.

  As another comparative example for suppressing the evaporation of the electrolytic solution from the sealing plate, a method of increasing the thickness of the phenol resin plate can be considered instead of using the rubber material 22 mixed with the glass flake powder. In this case, it is necessary to remarkably increase the thickness of the phenolic resin plate. On the other hand, in the sealing plate 20 of the present embodiment, the rubber material 22 obtained by mixing the glass flake powder is simply attached to the phenol resin plate 21 which is a general sealing plate material. With this configuration, the evaporation of the electrolyte can be suppressed, and the evaporation of the electrolyte can be sufficiently suppressed while suppressing a significant increase in the thickness of the sealing plate 20.

  As described above, by using the sealing plate 20 formed by adhering the rubber material 22 obtained by mixing the powder of glass flakes to the phenolic resin plate 21, the breaking strength of the sealing plate 20 can be increased. , Gas permeability can be lowered. Thereby, it is possible to realize an electrolytic capacitor having a large valve operating pressure and suppressing evaporation of the electrolytic solution.

  Further, a high-strength sealing plate with a small amount of gas permeation is obtained by a simple process of attaching a rubber material 22 mixed with scaly glass to a phenolic resin plate 21 generally used as the sealing plate 20. 20 can be obtained. Thereby, an electrolytic capacitor having a large valve operating pressure that suppresses the evaporation of the electrolytic solution can be obtained by a simple manufacturing process.

  In the above-described embodiment, the case where the rubber material 22 is provided on the outer surface of the electrolytic capacitor of the phenol resin plate 21 has been described. However, the present invention is not limited to this. You may make it provide in the surface or both surfaces.

Moreover, in the above-mentioned embodiment, although the case where the phenol resin board 21 was used as a resin board used for the sealing body 20 was described, it is not restricted to this, Other resin materials can be used.
In the above-described embodiment, the present invention is applied to an electrolytic capacitor having a rating of 50 [V], 15000 [μF], a diameter of 35 [mm], and a length of 50 [mm]. However, the present invention can be applied to electrolytic capacitors of various other sizes and specifications.

1 Anode foil 2 Cathode foil 3 Electrolytic paper (separator)
4 Anode lead 5 Cathode lead 6 Element stop tape 7 Capacitor element 8 Anode terminal 9 Cathode terminal 12 Exterior case 12A Bottom portion 14 Fixing material 15 Pressure valve 20 Sealing plate 21 Phenolic resin plate 22 Rubber material

Claims (3)

A capacitor element formed by superposing and winding the anode foil and the cathode foil of the valve metal through a separator;
A bottomed cylindrical outer case for storing the capacitor element;
A sealing body for sealing the opening of the outer case, and an electrolytic capacitor comprising:
An electrolytic capacitor using an elastic body mixed with scaly glass as the sealing body. The elastic body is
2. The electrolytic capacitor according to claim 1, wherein at least 0.5 wt% of the glass flake powder having an average thickness of 0.4 to 5.0 μm and an average particle diameter of 10 to 900 μm is mixed. . The sealing body is
The electrolytic capacitor according to claim 1, wherein the electrolytic capacitor is a resin plate to which the elastic body mixed with the glass flakes is attached.

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