JPH09232189A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce breakdown, burning or the like due to a deterioration of an anode foil and enhance the life by a structure wherein two or more leaves of anode foils of a substantially equal length in which an anode lead wire is connected to their center parts are connected parallel. SOLUTION: In a capacitor element 6, two leaves or more of anode foil 1 are disposed in parallel to wind. In this anode foil 1, a transformed film is formed in an etching foil of a valve action metal such as Al and a substantially equal length is formed. Further, one end of an anode lead wire 2 is connected to a substantial center pad of the anode foil 1 and the other end thereof is led out, and as the anode lead wire 2, a valve action metal foil such as untreated Al or a valve action metal foil forming a transformed film is employed. A cathode foil 4 has a width which is substantially same as the anode foil 1 and an etching foil of a valve action metal foil such as Al which is thinner than the anode foil 1 is employed. The anode foil 1 and the cathode foil 4 are overlapped and wound via an electrolytic paper 3, and the anode lead wire 2 and a cathode lead wire 5 are led out to form the capacitor element 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrolytic capacitors such as dry aluminum electrolytic capacitors.

[0002]

2. Description of the Related Art An electrolytic capacitor such as a dry aluminum electrolytic capacitor is formed by stacking an anode foil formed by etching an etching foil such as aluminum at a predetermined voltage and a cathode foil made of the etching foil through an electrolytic paper and winding them. The formed capacitor element is used. In particular, as the anode foil, a plurality of lead wires for an anode are connected to one long foil at equal intervals. With such a structure, the current capacity flowing through the electrolytic capacitor can be increased, and the equivalent series resistance can be reduced, so that heat generation can be reduced and deterioration due to the heat generation can be suppressed.

[0003]

However, when a part of the anode foil deteriorates and becomes short-circuited, a large current concentrates on the deteriorated part even if the other part is normal. for that reason,
The electrolytic capacitor heats up and the pressure inside the case rises,
There are drawbacks such as the lid popping out, the case breaking, or burning.

It is an object of the present invention to provide an electrolytic capacitor which is capable of improving the above-mentioned drawbacks, reducing destruction and burning due to deterioration of the anode foil, and improving the life thereof.

[0005]

In order to achieve the above object, the present invention provides an anode foil to which an anode lead wire is connected,
In an electrolytic capacitor having a capacitor element in which a cathode foil and a cathode foil are superposed and wound via electrolytic paper, two or more anode foils of substantially equal length with one anode lead wire connected to the center are connected in parallel. The present invention provides an electrolytic capacitor characterized by the following.

According to the present invention, when one of the anode foils is deteriorated, the current concentrates on the deteriorated portion and finally becomes a short circuit state. Then, the short circuit causes the anode lead wire connected to the anode foil to flow a large current due to this short circuit, and melts and cuts in the middle. Therefore, this anode foil is opened electrically. Therefore, the electrolytic capacitor
Although the capacity is reduced only in the open anode foil part, the normal function as a capacitor can be maintained without destruction or burning.

Since the lead wire for the anode is connected to the central portion of the anode foil, the equivalent series resistance can be reduced as compared with the case where the lead wire is connected to other positions such as the end portion. Therefore, heat generation of the electrolytic capacitor can be suppressed and the life can be improved.

Further, since the anode lead wire is connected to the central portion of the anode foil and the anode foil has a substantially equal length, the current flowing through each anode foil can be made substantially the same. Therefore, it is possible to suppress the tendency of deterioration due to individual anode foils. Therefore, the life of the electrolytic capacitor can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an anode foil, and two or more foils are arranged in parallel and wound. The anode foil 1 is formed by forming a chemical conversion film on an etching foil of a valve metal such as aluminum and has a substantially uniform length. 2
Is a lead wire for an anode, one end of which is connected to substantially the center of the anode foil 1 and the other end of which is drawn out. As the anode lead wire 2, a foil of valve-action metal such as untreated aluminum or a valve-action metal foil having a chemical conversion film is used. 3 is electrolytic paper, which is made of Kraft paper or Manila paper having a density of 0.4 to 0.7 and a thickness of 30 to 60 μm, and is used by stacking one or two or three sheets according to the rating of the electrolytic capacitor. This electrolytic paper 3 is wider than the anode foil 1. Reference numeral 4 denotes a cathode foil, which is substantially the same width as the anode foil 1 and is made of an etching foil of a valve action metal foil such as aluminum which is thinner than the anode foil 1. Reference numeral 5 is a cathode lead wire connected to the cathode foil 4, and is made of untreated valve metal such as aluminum. Then, the anode foil 1 and the cathode foil 4 are overlapped with each other via the electrolytic paper 3 and wound, and the anode lead wire 2 and the cathode lead wire 5 are drawn out to form the capacitor element 6.

Further, the capacitor element 6 is impregnated with an electrolytic solution. As the electrolytic solution, for example, an organic acid-based solution in which various substances such as boric acid, ammonium borate, phosphoric acid, and mannite are dissolved in a solvent composed of polyhydric alcohol such as ethylene glycol, polypropylene glycol, and glycerin is used. .

The capacitor element 6 impregnated with the electrolytic solution
Is stored in the case 7, as shown in FIG. Case 7
Is made of metal such as aluminum or insulating resin such as epoxy resin, and is usually cylindrical. A cover 8 made of insulating resin is attached to the end of the case 7. The lid 8 may be a laminated plate such as a rubber-clad bake plate. The lid 8 is provided with an anode terminal 9 and a cathode terminal 10 penetrating therethrough. Although screw terminals are used as the anode terminal 9 and the cathode terminal 10, lug terminals or the like may be used instead. The anode lead wire 2 and the cathode lead wire 5 are connected to the anode terminal 9 and the cathode terminal 10, respectively. Thereby, the anode foils 1 can be connected in parallel. Further, a through hole 11 is provided in the lid 8, and an explosion proof valve 12 is inserted and fixed in the through hole 11. Further, the case 7 is filled with a fixing agent 13 such as pitch, atactic polypropylene, or silicone resin to fix the capacitor element 6 to the case 7. The surface of the case 7 is covered with an insulating tube 14 to insulate the electrolytic capacitor 15.

Next, the manufacturing method of the above embodiment will be described. First, in order to manufacture the anode foil 1, the thickness number 1
A valve action metal foil of about 0 to 100 μm is used. That is, first, this foil is immersed in a liquid such as hydrochloric acid or sulfuric acid, and roughened by a direct current etching method or the like. After roughening, boil in pure water. After boiling, in a chemical conversion liquid such as boric acid or oxalic acid, the voltage is gradually increased to about 1.4 times the rated voltage to apply the voltage, and the chemical conversion is performed to form a chemical conversion film. After the chemical conversion treatment, phosphoric acid treatment or the like is performed to stabilize the composition as needed, and then firing treatment is performed. After firing treatment,
Cut into pieces of arbitrary width and length. The anode foil 1
It may be cut into the length at the time of the final winding either before the winding operation or during the winding operation.

When an untreated valve-action metal foil is used, the anode lead wire 2 is cut into a desired width and length before or during the winding process. After cutting, the anode foil 1 is connected to a substantially central portion by a cold weld method, a caulking method, or the like. When a foil having a chemical conversion coating formed on a valve metal foil is used, it is manufactured as follows. That is, first, the valve action metal foil is formed at a voltage higher than the formation voltage of the anode foil 1 to form a formation film. After chemical conversion, phosphoric acid treatment and baking treatment are performed, and then chemical conversion treatment is performed to restore the chemical conversion film. After the re-formation treatment, similarly to the untreated case, it is cut before or during the winding treatment and connected to the anode foil 1.

The cathode foil 4 is manufactured by roughening a valve-action metal foil thinner than the anode foil 1, then subjecting it to phosphoric acid treatment, and cutting it to a size of arbitrary width and length. Then, the cathode lead wire 5 is connected to the cut cathode foil 4 by a cold weld method or a caulking method.

Then, as shown in FIG. 1, the anode foil 1, the electrolytic paper 3 and the cathode foil 4 are wound to form a capacitor element 6. After forming the capacitor element 6, the electrolytic solution is impregnated by a vacuum impregnation method or a vacuum pressure impregnation method.

After impregnation with the electrolytic solution, the capacitor element 6 is housed in the case 7. After housing in the case 7, the anode lead wire 2 and the cathode lead wire 5 are connected to the anode terminal 9 and the cathode terminal 10, respectively. After the connection, the fixing agent 13 before curing is filled in the bottom of the case 7, and the fixing agent 13 is cured to fix the capacitor element 6. After fixing, the lid 8 is attached to the end of the case 7 to seal the case 7. After the case 7 is hermetically sealed, in a high temperature atmosphere, a voltage not less than the rated voltage is finally applied while gradually increasing the voltage to perform an aging treatment. After the aging treatment, the case 7 is covered with the tube 14.

[0017]

As described above, according to the present invention, since two or more anode foils each having a substantially equal length with one anode lead wire connected to the central portion are connected in parallel, the case can be Electrolytic capacitors that can reduce the number of accidents such as breakage, flying of the lid, and burning, and have a longer life can be obtained.

[Brief description of drawings]

FIG. 1 is a development view of a capacitor element used in an embodiment of the present invention.

FIG. 2 shows a cross-sectional view of an electrolytic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Anode foil, 2 ... Anode lead wire, 3 ... Electrolytic paper,
4 ... Cathode foil, 6 ... Capacitor element, 15 ... Electrolytic capacitor.

Claims (1)

[Claims] 1. In an electrolytic capacitor having a capacitor element in which an anode foil to which an anode lead wire is connected and a cathode foil are superposed and wound with electrolytic paper interposed therebetween, one anode lead wire is connected to a central portion. An electrolytic capacitor characterized in that two or more anode foils of substantially equal length are connected in parallel.