JPS607480Y2 - aluminum electrolytic capacitor - Google Patents

Description

[Detailed description of the invention] This invention relates to aluminum electrolytic capacitors, and in particular, forms a terminal part on the case of a dry aluminum electrolytic capacitor to enable face bonding (direct attachment to the surface) to the wiring conductor of a printed circuit board. Concerning what has been done.

Generally, as electronic devices become smaller and more precise, capacitors used in the electronic devices are required to be smaller and have higher reliability, and aluminum electrolytic capacitors are no exception.

FIG. 1 shows the structure of a conventional aluminum electrolytic capacitor.

In the figure, a sealing comb 4 is fitted into the opening of the aluminum case 2 to maintain airtightness, and in order to strengthen the bond between the aluminum case 2 and the sealing rubber 4, the area near the opening edge of the aluminum case 2 is The sealing rubber 4 is compressed by crimping to a small diameter, and the opening edge of the aluminum case 2 is curved toward the center so as to surround the sealing rubber 4.

The aluminum electrolytic capacitor element 6 is sealed inside the aluminum case 2, which is sealed with the sealing rubber 4 to maintain a high level of airtightness.

This aluminum electrolytic capacitor element 6 has an aluminum foil on the cathode side and an electrode foil on the anode side, on the surface of which a dielectric oxide film is formed by coating, in a wound form with a separator interposed between the two. It is impregnated with electrolyte.

An anode terminal section 8 and a cathode terminal section 10 made of aluminum are drawn out from the ends of the aluminum electrolytic capacitor element 6, and are connected to aluminum foil on the anode side or the cathode side. External lead part 1
2.14 are electrically connected by welding or the like.

Each terminal portion 8, 10 and each external lead portion 12゜14 are
The connecting part is positioned inside the sealing rubber 4 and penetrated,
Only the external lead portions 12 and 14 are drawn out from the sealing rubber 4.

In such conventional aluminum electrolytic capacitors, in order to firmly maintain the airtightness of the aluminum case 2 and avoid evaporation of the electrolyte, the volume of the sealing rubber 4 is increased to increase the joint area with the inner surface of the aluminum case 2. taking it.

Therefore, the volume ratio occupied by the sealing rubber in the aluminum electrolytic capacitor element becomes extremely large.
This causes electrolytic capacitors to become larger.

However, if the sealing rubber is made smaller, the airtightness of the aluminum case 2 will be reduced accordingly, and the reliability of the capacitor will be lost.

Conventionally, as shown in FIG. 2, a terminal portion 22.24 is formed on the surface of a component body 20 instead of a lead wire, and this terminal portion 22.24 is directly fixed onto a wiring board 26 with solder 28. has proposed an electrolytic capacitor that can be face bonded in which the component body 20 is wired.

In this electrolytic capacitor, metal caps are fitted to both ends of a wound capacitor element, aluminum foil is selectively connected to each metal cap on the anode side or the cathode side, and synthetic resin is applied to the surface of the capacitor element. It is attached and has an exterior covering.

In an electrolytic capacitor constructed in this way, the outer periphery of the capacitor element is covered with synthetic resin, so in order to ensure the breathing effect of the capacitor element, each metal cap has its opening end drawn to allow the capacitor element to A space sufficient for breathing is provided.

However, when an electrolytic capacitor is configured in this manner, there are the following disadvantages.

(a) Since synthetic resin is attached to the capacitor element, it is necessary to take measures such as installing a space in the metal cap to ensure its breathing effect, and the electrolytic capacitor element is impregnated with electrolyte. Therefore, it is impractical to integrally attach the synthetic resin to the capacitor element.

(b) When a metal cap is fitted to a capacitor element, unnecessary stress is applied to the aluminum foil, causing problems such as damage to the dielectric oxide film of the aluminum foil on the anode side.

(C) It is not easy to maintain airtightness by bonding the synthetic resin and the metal cap, and there is a risk that the airtightness of the exterior will be insufficient.

Therefore, the present invention reduces the volume ratio occupied by the conventional sealing rubber to downsize the entire device, improves airtightness and improves reliability, and damages the dielectric oxide film on the aluminum foil on the anode side. The aim is to provide an aluminum electrolytic capacitor that enables face bonding without any problems.

That is, the present invention provides an aluminum electrolytic capacitor element formed by winding aluminum foil on the anode side and the cathode side with a separator interposed therebetween and impregnating the inside with an electrolytic solution, and a housing for housing the aluminum electrolytic capacitor element. an insulating cylinder having a space and a recess formed on the outer periphery; and an insulating cylinder that fits into both ends of the insulating cylinder and is crimped to be engaged with the recess to close the insulating cylinder, and the aluminum electrolytic capacitor. A terminal cap that is electrically connected to an anode or cathode tab drawn out from the element to constitute an anode or cathode terminal, and a terminal cap that is inserted in a compressed state between this terminal cap and the insulating cylinder. It is characterized by being constructed from an elastic member that maintains airtightness between the two by its expansion force.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 3 shows an embodiment of the aluminum electrolytic capacitor of the present invention.

In FIG. 3, an aluminum electrolytic capacitor element 30
In this method, an aluminum foil on the cathode side and an aluminum foil on the anode side, on which a dielectric oxide film is formed on the surface by skinning, are wound with a separator interposed between them, and then impregnated with an electrolyte. It is something that

The insulating tube 32 in which the aluminum electrolytic capacitor element 30 is housed is formed of an insulating material such as an insulating resin into a hollow body with a storage space inside. Recesses 38 and 39 for locking caps 34 and 36 are formed.

The terminal cap 34, 36 is an aluminum container with one end open, and its outer surface is plated with a solderable metal layer such as copper or tin to enable soldering. has been done.

Note that the terminal caps 34 and 36 are intended to enable direct soldering to a wiring board (not shown), so in order to stabilize the connection, they are cylindrical bodies with a flat part formed on the - side or It may be composed of a rectangular cylindrical body, and
To enable soldering, a clad material having a solderable metal plate bonded to the outer surface may be used instead of plating.

Aluminum tabs 40 and 42 derived from the aluminum electrolytic capacitor element 30 are connected to approximately the center of the inner surface of the terminal cap 34, 36 by ultrasonic welding or the like.

For example, tab 40 is on the anode side and tab 42 is on the cathode side.

Therefore, the terminal caps 34 and 36 are attached to the insulating tube 32.
A terminal for an anode and a terminal for a cathode are formed through the terminal.

An elastic member 44.46, which is made of a rubber ring or the like and constitutes a backing, is housed in the corner of the inner surface of the terminal cap 34.36. is in contact.

This elastic member 44.46 is connected to the terminal cap 34.36.
It is provided to close the insulating tube 32 by making the joint between the terminal cap 34, 36 and the insulating tube 32 airtight, and to compress the terminal cap 34, 36 and the insulating tube 32 so that an expansion force acts between them. It is inserted in the state.

This compressed state is maintained, and the expansion force of the elastic members 44, 46 acts between the terminal cap 34, 36 and the insulating tube 32 to maintain a high degree of airtightness.
The vicinity of the end of the insulating cylinder 32 is crimped and secured to the recesses 38 and 39 of the insulating cylinder 32.

With the above structure, the insulating cylinder 32 is tightly kept airtight by the terminal caps 34, 36 and the elastic members 44, 46, and evaporation of the electrolytic solution can be prevented.

As a result, since the aluminum electrolytic capacitor element 30 is placed in a sealed state, deterioration of the electrical characteristics of the aluminum electrolytic capacitor element 30 is prevented and reliability is maintained.

Furthermore, since the terminal caps 34 and 36 can be directly soldered to the wiring board, handling of wiring such as connection on the wiring board is facilitated and simplified.

Furthermore, as is clear from the comparison with the sealing rubber in Figure 1, the elastic members 44 and 46 are extremely small and their volume occupancy is extremely low, making it possible to miniaturize the capacitor and increase its capacity. .

Moreover, even if the aluminum electrolytic capacitor element 30 becomes longer in the axial direction to increase the capacitance, the elastic member 4
There is no need to change the size or form of 44.46, and as a result, the larger the capacitor, the smaller the volume occupied by the elastic member 44.46.

Therefore, from this point of view as well, it can be understood that miniaturization of capacitors is a distant relative.

Next, a method for manufacturing an aluminum electrolytic capacitor according to the present invention will be explained.

As shown in FIG. 4, an elastic member 44 or 46 is inserted into the terminal cap 34 or 36.

Next, tabs 40 and 42 derived from the aluminum electrolytic capacitor element 3o are attached to terminal caps 34 and 3, respectively.
Weld to the inner surface of 6.

In this case, after welding one terminal cap 34 and tab 40, the insulating tube 32 is fitted onto the aluminum electrolytic capacitor element 30, and then the other is welded.

Next, as shown in FIG.
After fitting the terminal cap 34, 36 into the insulating tube 32, force is applied in the direction shown by arrow A to compress the elastic member 44, 46, and force is applied in the direction of arrows B and C to push the terminal cap 34, 36 into the insulating tube 32.
Tighten toward the recesses 38 and 39.

As a result, the terminal caps 34 and 36 are secured to the insulating cylinder 32 while maintaining a strong seal.

6 and 7 show other embodiments of the aluminum electrolytic capacitor of the present invention.

In the embodiment shown in FIG. 6, the elastic member 44 shown in FIG.
46, an elastic member 44A having a stepped portion 50 that partially supports the corner portion of the aluminum electrolytic capacitor element 30;
It is composed of 46A.

By doing this, the insulating tube 32 and the terminal cap 34.
Not only can the aluminum electrolytic capacitor element 30 be airtightly joined to the aluminum electrolytic capacitor element 36, but also the aluminum electrolytic capacitor element 30 can be held elastically, and dangers such as breakage of the tabs 40 and 42 due to vibration can be avoided.

In the embodiment shown in FIG. 7, the concave portion of the insulating tube 32 that locks the terminal cap 34 or 36 is constituted by one concave portion 52.

This has the advantage that the insulating tube 32 can be easily formed.

In addition, in this example, the recesses of the insulating tube that lock the terminal caps were formed all around the insulating tube, but there is no need to form such recesses, and the recesses are formed at regular intervals around the insulating tube. may be formed.

In this case, the terminal cap may be crimped according to the region where the recess is formed, and the same effect as in the embodiment described above can be obtained.

As explained above, according to the present invention, the following effects can be obtained.

(a) Reliability is improved because the elastic member maintains a high level of airtightness between the insulating tube and the terminal cap, and the terminal cap eliminates the need to pass lead wires on the wiring board, which was previously required. Connection can be made by face bonding, and the volume of the elastic member can be made smaller than that of conventional sealing rubber, so the entire capacitor can be made smaller.

(b) Also, compared to conventional electrolytic capacitors that allow face bonding, in which a metal cap is directly fitted to the capacitor element, and a synthetic resin is attached to the outer surface of the capacitor element to provide an exterior covering. In this invention, there is no need to take measures against the breathing effect of the capacitor element, there is no manufacturing difficulty in attaching synthetic resin to the capacitor element impregnated with electrolyte, and it is possible to fit the metal cap to the capacitor element. There is no inconvenience such as damage to the dielectric oxide film of the aluminum foil on the anode side due to stress caused by this, and the exterior can ensure sufficient airtightness and maintain stable electrical characteristics over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a conventional aluminum electrolytic capacitor, Fig. 2 is an explanatory diagram showing how electrical parts are mounted on a wiring board by face bonding, and Fig. 3 is an example of the aluminum electrolytic capacitor of the present invention. Fig. 4 is a sectional view showing the terminal cap and the elastic member;
The figure is an explanatory view showing an assembly method, and FIGS. 6 and 7 are longitudinal sectional views showing other embodiments of the present invention. 30... Aluminum electrolytic capacitor element, 3
2... Insulating cylinder, 34.36... Terminal cap, 38.39, 52... Recessed part, 40,
42...Tab, 44, 44A, 46, 46A・
...Elastic member, 50...Stepped portion.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. An aluminum electrolytic capacitor element formed by winding aluminum foil on the anode side and the cathode side with a separator interposed therebetween and impregnating the inside with an electrolyte, and housing this aluminum electrolytic capacitor element. an insulating cylinder having a storage space and a recess formed on the outer periphery, and the aluminum A terminal cap that is electrically connected to the anode or cathode tab pulled out from the electrolytic capacitor element to constitute an anode or cathode terminal, and a terminal cap that is compressed between the terminal cap and the insulating tube. An aluminum electrolytic capacitor comprising an elastic member that is inserted and maintains airtightness between the two by its expansion force. 2. Utility model registration claim 1, characterized in that a step part for supporting the aluminum electrolytic capacitor element is provided in a part of the elastic member, and the aluminum electrolytic capacitor element is elastically supported by the step part. Aluminum electrolytic capacitors as described in section.