JPH08111353A - Aluminum electrolytic capacitor - Google Patents

Abstract

PURPOSE: To prevent an electrolyte from leaking through the gap between the hole made through a sealing body and a terminal penetrating the through hole by filling the space between the upper surface of a capacitor element in an outer case and the sealing body with silicon thereby protecting the terminal against corrosion due to alkali. CONSTITUTION: A capacitor element 3 impregnated with electrolyte is encased on a tubular bottomed outer case 2. The capacitor element 3 comprises an aluminum anode foil and an aluminum cathode foil wound through a separator paper. The anode and cathode foils of the capacitor element 3 are bonded, respectively, with a lead terminal 4 and a part of which is collapsed to for a battledore part 4a and a lead wire 6 is welded to an uncollapsed rod part 5. Prior to fitting a sealing body 7, silicon putty 9 is placed on the upper surface and then the sealing body 7 is placed thereon and pushed downward thus filling the space between the capacitor element 3 and the sealing body 7 fully with the silicon 9. This structure prevents leakage of the electrolyte.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aluminum electrolytic capacitor.

[0002]

2. Description of the Related Art As shown in FIG. 3, in an aluminum electrolytic capacitor 20, a capacitor element 21 formed by winding an aluminum anode foil and an aluminum cathode foil with separator paper is impregnated with a driving electrolytic solution. After housing the capacitor element 21 in a bottomed outer case 22 made of aluminum having an opening on one side, a rubber sealing body 23 is arranged and closed in the opening of the outer case to seal the periphery of the opening of the outer case. It has a closed structure by processing. It should be noted that in FIG. 3, the aluminum electrolytic capacitor 20 is shown in a state at the time of manufacture, and is upside down during use.

Lead terminals 2 are provided on the anode foil and the cathode foil, respectively.
4 is fixed. The lead terminal 24 is formed by crushing a part of a round rod-shaped aluminum wire to form a battledore portion 25, and the lead wire 27 is welded to the uncrushed round rod portion 26. The battledore portion 25 of the lead terminal 24 is fixed to the anode foil and the cathode foil by crimping or the cold weld method, the round bar portion 26 penetrates the through hole 28 of the rubber sealing body 23, and the lead wire 27 welded to it is external. Have been pulled out.

As a driving electrolytic solution, in recent years, a quaternary salt electrolytic solution, that is, a quaternary ammonium salt of o-phthalic acid or a solvent such as γ-butyrolactone or ethylene glycol, is used in order to achieve low impedance. A quaternary salt electrolyte in which a quaternary ammonium salt of maleic acid is dissolved as a solute is used.

The electrolytic solution is impregnated into a capacitor element under a vacuum and is held on a rolled aluminum anode foil and cathode foil or separator paper, but the held amount varies somewhat. If the holding amount is large, the electrolytic solution may ooze out to the surface of the capacitor element 21 that faces the rubber sealing body 23 in use, and the surface of the rubber sealing body may be wet.

[0006] In particular, when an electrolytic solution containing a quaternary salt as a solute as described above is used, when an electric field is applied, the lead terminal, particularly the cathode, between the capacitor element 21 and the rubber sealing body 23 is applied. PH of the electrolyte around the side lead terminal
Is known to become a strong alkali. For this reason, the round bar portion 26 near the lead terminal on the cathode side entering the through hole 28 of the rubber sealing body 23 is eroded, and the through hole 28 of the rubber sealing body 23 and the through hole 28 are closely contacted and penetrated during a long period. There is a case in which a gap is formed between the lead rod on the cathode side and the round bar portion 26, and the electrolytic solution may leak to the outside from this gap.

Therefore, conventionally, an anodic oxide film or a chemical conversion film is formed on the round bar portion of the lead terminal so that the round bar portion is not corroded by alkali.

[0008]

However, even in the method of forming the anodic oxide film or the chemical conversion film, there is a possibility that the electrolyte may be corroded by the alkali and leak the electrolyte to the outside when it is used for a long time.

The present invention provides an aluminum electrolytic capacitor which prevents the terminal from being corroded by alkali and prevents the electrolytic solution from leaking to the outside between the through hole of the sealing body and the terminal penetrating the sealing hole. It is an object.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a capacitor element in which an aluminum anode foil and a cathode foil are wound around separator paper and impregnated with an electrolytic solution is housed in an outer case having a bottom, and a capacitor is provided. In the aluminum electrolytic capacitor in which one end of the terminal fixed to the anode foil and the cathode foil of the element is drawn out of the outer case through the through hole of the sealing body that seals the opening of the outer case, The space between the upper surface of the capacitor element and the sealing body is filled with silicon.

Even if the terminal is a flat tab terminal as a whole, it is made of a round bar and the part fixed to the anode foil and the cathode foil is flat like a battledore, and the lead wire drawn out of the outer case is welded to the other end. It may be a lead terminal that has been used. The silicon is preferably putty. Silicon is placed in a spherical or plate-like shape between the capacitor element and the sealing body during the assembly of the aluminum electrolytic capacitor, and the silicon is crushed when the sealing body is pressed toward the capacitor element. The space between the upper surface of the capacitor element and the sealing body is filled without any gap to form a silicon layer.

Examples of silicon include Cylmate 82-C manufactured by Toshiba Silicon Co., Ltd. and #EU manufactured by Fuji Polymer Co., Ltd.

[0013]

Since the space between the upper surface of the capacitor element and the sealing body is filled with silicon, the terminal is not exposed between the capacitor element and the sealing body, and the terminal is not corroded by alkali.

[0014]

FIG. 1 shows a state in which an aluminum electrolytic capacitor according to an embodiment of the present invention is being assembled. The aluminum electrolytic capacitor 1 is placed in a cylindrical outer case 2 having a bottom and is impregnated with an electrolytic solution. The capacitor element 3 has a capacitor element 3, and the capacitor element 3 is formed by winding an aluminum anode foil and an aluminum cathode foil via separator paper.

Lead terminals 4 are fixed to the anode foil and the cathode foil of the capacitor element 3, respectively. The lead terminals 4 crush a part of a round bar-shaped aluminum wire to form a battledore portion 4a,
The lead wire 6 is welded to the round bar portion 5 which is not crushed. The battledore portion 4a of the lead terminal 4 is fixed to the anode foil and the cathode foil by caulking, cold welding, or the like, and the round bar portion 5 penetrates the through hole 8 of the rubber sealing body 7 and the round bar portion 5
The lead wire 6 welded to is drawn out to the outside.

At the time of assembling the aluminum electrolytic capacitor, putty-like silicon 9 is placed on the upper surface of the capacitor element 3 before mounting the sealing body 7. As the silicon 9, a plurality of spherical or dumpling-shaped ones are used. In addition to spherical silicon, plate-shaped silicon may be used. The plate-shaped silicon may have a size that covers the entire upper surface of the capacitor element 3 or a plurality of plates that have a size that covers a part of the capacitor element 3. Good. Further, the plate-shaped silicon may be provided with a hole through which the lead terminal 4 penetrates.

When silicon 9 is placed on the upper surface of the capacitor element 3 and the sealing body 7 is placed thereon and the sealing body 7 is pressed downward, the silicon is crushed and the capacitor element 3
And the space between the sealing body 7 and the sealing body 7 is expanded to completely fill the space. At that time, silicon is used as the capacitor element 3 as shown in FIG.
And a part of the silicon also enters the through hole 8 of the sealing body 7.

By thus filling the space between the capacitor element 3 and the sealing body 7 with no space, the aluminum electrolytic capacitor in a used state (a state in which FIG. 1 is inverted after assembly) is a capacitor element. The electrolytic solution impregnated in 3 does not exude to the sealing body 7 side. Further, since the part of the lead terminal 4 from the capacitor element 3 to the through hole 8 of the sealing body 7 is covered with silicon and is not exposed, the lead terminal 4, especially the round bar portion 5 may be corroded by alkali. Absent.

<Test Example> Aluminum electrolytic capacitor according to the present invention (rated 6.3V 100μF, diameter 6.3m)
m and height 7 mm) were used as Test Examples 1 to 3, and 200 conventional products not filled with silicon having the same rating and size as the comparative examples were manufactured. As the electrolyte,
A quaternary salt electrolyte solution containing 25% by weight of tetramethylammonium hydrogen phthalate as a solute and γ-butyrolactone as a solvent was used together. In Test Examples 1 to 3, #EU made by Fuji Polymer was used as silicon, and the amount was sufficient to fill the space between the upper surface of the capacitor element and the sealing body. In Test Example 1, this was made into three spherical shapes, and Test Example 2
Was used as two plate-shaped members that partially cover the upper surface of the capacitor element, and in Test Example 3 as one plate-shaped member that covers the entire upper surface of the capacitor element. The plate-shaped body was provided with a hole through which the lead terminal penetrates.

60 aluminum electrolytic capacitors
After applying the rated voltage for up to 2000 hours at a humidity of 95% and a maximum of 2000 hours, the electrolyte leaked between the round bar of the terminal on the cathode side and the through hole of the rubber sealing body that penetrated through it. After confirming how many were there with a 20 × stereomicroscope, Table 1
I got a result like.

[0021]

[Table 1]

From these results, it can be seen that the aluminum electrolytic capacitor according to the present invention has an excellent effect on leakage of the electrolytic solution.

[0023]

According to the present invention, a capacitor element formed by winding an aluminum anode foil and a cathode foil with separator paper impregnated with an electrolytic solution is housed in an outer case having a bottom, and the anode foil of the capacitor element and In an aluminum electrolytic capacitor in which one end of the terminal fixed to the cathode foil is drawn out of the outer case through the through hole of the sealing body that seals the opening of the outer case, the upper surface of the capacitor element in the outer case and Silicon is filled in the space between the sealing body,
The electrolytic solution impregnated into the capacitor element does not ooze out, and the terminal is covered with silicon and is not exposed, so it is recommended to use an electrolytic solution that uses a quaternary salt that becomes a strong alkali near the terminal on the cathode side. The round bar of the terminal on the cathode side is not eroded, and the electrolyte leakage can be prevented.

Therefore, the γ-butyrolactone quaternary ammonium salt type electrolytic solution having the highest conductivity can be used as the electrolytic solution of the aluminum electrolytic capacitor, and the secondary smoothing capacitor can be downsized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state during assembly of an example of an aluminum electrolytic capacitor of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a state of being filled with silicon.

FIG. 3 is an exploded view of an aluminum electrolytic capacitor.

[Explanation of symbols]

 1 Aluminum Electrolytic Capacitor 2 Exterior Case 3 Capacitor Element 3a Anode Foil 3b Cathode Foil 3c Separator 4 Terminal (Lead Terminal) 4a Battledore Part 5 Round Bar Part 6 Lead Wire 7 Sealing Body 8 Through Hole 9 Silicon

Claims (1)

[Claims] 1. A capacitor element obtained by winding an aluminum anode foil and a cathode foil with separator paper impregnated with an electrolytic solution in a bottomed outer case, and storing the capacitor element in an anode foil and a cathode foil. In an aluminum electrolytic capacitor in which one end of the fixed terminal is pulled out of the outer case through the through hole of the sealing body that seals the opening of the outer case, the upper surface of the capacitor element in the outer case and the sealing body An aluminum electrolytic capacitor, characterized in that the space between is filled with silicon.