JPH0513532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a solid electrolytic capacitor, and particularly to a structure in which a shape memory alloy is incorporated in a solid electrolytic capacitor.

[Conventional technology]

In general, the failure mode of solid electrolytic capacitors is often short-circuit failure, and when a large short-circuit current flows, the capacitor element generates heat and may even burn out. In the event of a failure due to this excessive short-circuit current, it is necessary to change the failure mode from short circuit (short circuit) to open (oven) in order to protect the circuit components, using a fuse as shown in Figure 4. The means are known. As a conventional technology, for example,
There is a solid electrolytic capacitor with a built-in fuse, as shown in Publication No. -250974.

In FIG. 4, the present solid electrolytic capacitor includes a solid electrolytic capacitor element 5, an anode external terminal 7 drawn out to the outside via an anode lead 8, and a cathode external terminal 3 drawn out to the outside via a fuse 6.
An exterior resin 4 is provided.

[Problem that the invention seeks to solve]

In the conventional solid electrolytic capacitor with a fuse described above, as shown in FIG. This is an interposed connection. Therefore, the first drawback is that during soldering, low temperature solder must be used that does not damage the capacitor element, which does not provide good adhesion. If high-temperature solder is used to increase adhesion, the drawback is that the capacitor cannot withstand high heat. The second drawback is that the area of the foamed resin is small, which prevents the fuse from being completely blown, resulting in the fuse material being reattached after being blown, resulting in a short circuit and continuing to maintain electrical connection. It has the disadvantage of being

SUMMARY OF THE INVENTION An object of the present invention is to provide a solid electrolytic capacitor which solves the above-mentioned drawbacks, which quickly melts down in the event of a short circuit accident, and which prevents short circuits from occurring again.

[Means for solving problems]

The structure of the solid electrolytic capacitor of the present invention is such that a shape memory alloy whose surface is coated at least in part with a foamed resin having heat insulating properties is inserted and connected between a solid electrolytic capacitor element and an external terminal, and an insulating exterior is provided. It is characterized by

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view of a solid electrolytic capacitor according to an embodiment of the present invention. In the figure, the present solid electrolytic capacitor is constructed by anodizing an anode body made of a valve metal such as tantalum, and sequentially depositing a manganese dioxide layer 5a, a carbon layer 5b, and a silver paste layer 5c thereon. A solid electrolytic capacitor element (hereinafter abbreviated as element) 5 having an anode portion is formed.
Furthermore, an anode lead 8 planted on this element 5
and the anode external terminal 7 are connected by means such as welding. Next, the element 5 and the end portion 1 of the shape memory alloy 1
a and then connect the other end 1b of the shape memory alloy 1 to the cathode external terminal 3.
and then apply exterior resin 4 such as epoxy.
with an insulated exterior to form a solid electrolytic capacitor.

FIG. 2 is an enlarged cross-sectional view of the insertion connection portion of the shape memory alloy 1 shown in FIG. 1. As shown in FIG. 2, for example, an end portion 1a of the shape memory alloy 1 bent in a zigzag manner is connected to the element 5 using a conductive adhesive or the like, and the other end portion 1b is contact-connected to the cathode external terminal 3.

Next, a foamed resin material 2 that can generate air bubbles inside, such as a foamed resin material made by adding a foaming material to a thermoplastic resin emulsion, is applied so as to cover at least a portion of the bridged shape memory alloy 1. , perform foaming treatment.

By this foaming treatment, the surface of the shape memory alloy 1 is covered with the foamed resin 2 containing air bubbles.

In this embodiment, the foamed resin 2 swelled with gas is used.
Since the periphery of the shape memory alloy 1 is covered with the heat insulating effect, the shape memory alloy 1 contracts and deforms with a relatively low current, and the cathode external terminal 3 and the element 5 can be separated and immediately opened.

FIG. 3 is a sectional view of a solid electrolytic capacitor according to another embodiment of the present invention. In the figure, in the solid electrolytic capacitor of this embodiment, a solid electrolytic capacitor element 5 having a silver paste layer 5a, a carbon layer 5b, a manganese dioxide layer 5c, etc. is formed in the same manner as in the previous embodiment. Next, the anode lead 8 planted on this element 5 and the anode external terminal 7 formed into an L-shaped cross section are connected by means such as welding. Next, after connecting the end 3a of the cathode external terminal 3 and the end 1b of the shape memory alloy 1 with a conductive adhesive or the like, the other end 1a of the shape memory alloy 1 is connected.
is connected to the cathode portion of the element 5, and then insulated with an exterior resin 4 such as epoxy using a resin dip or the like to form a solid electrolytic capacitor.

Next, a foamed resin material 2 that can generate air bubbles inside, such as a foamed resin material made by adding a foaming material to a thermoplastic resin emulsion, was applied so as to cover at least a portion of the bridged shape memory alloy 1. Later, foaming treatment is performed.

By this foaming treatment, the surface of the shape memory alloy 1 is covered with the foamed resin 2 containing air bubbles.

〔Effect of the invention〕

As explained above, the present invention has the following effects.

(i) Since the shape memory alloy can be covered with a foamed resin that does not interfere with shape deformation, the solid electrolytic capacitor element and the external terminal can be completely opened.

(ii) By covering the shape memory alloy with foamed resin,
Since the heat conduction from the shape memory alloy to the surroundings is reduced and the shape deformation current of the shape memory alloy can be kept low, accidents such as the capacitor element overheating and burning can be prevented.

(iii) When connecting shape memory alloys, it is possible to use a conductive adhesive or the like to prevent short-circuit failures due to solder melting, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a solid electrolytic capacitor according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part of the capacitor shown in FIG. 4 is a sectional view of a conventional solid electrolytic capacitor with a fuse. 1... Shape memory alloy, 2... Foamed resin, 3...
Cathode external terminal, 4... Exterior resin, 5a... Manganese dioxide layer, 5b... Carbon layer, 5c... Silver paste layer, 5... (Solid electrolytic capacitor) element,
6...Fuse, 7...Anode external terminal, 8...Anode lead.

Claims (1)

[Claims] 1. A shape memory alloy whose surface is at least partially covered with a foamed resin having heat insulating properties is inserted and connected between a solid electrolytic capacitor element and a cathode external terminal to form an insulating exterior. solid electrolytic capacitor. 2. The solid electrolytic capacitor according to claim 1, wherein the foamed resin is made of a material obtained by adding a foaming material to a thermoplastic resin.