JP2000306789A - Capacitor having case provided with protective mechanism and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor with protective mechanism in a substrate mounting-type, which makes a cover board swell to be flat with pressure in a case which becomes high, when the capacitor is abnormal. SOLUTION: Outer terminal metal fittings 5 with outer brims 4, which are made of extending metal, are inserted into the holes of ring packings 1b that are force-fitted to the holes 1a of a metallic cover board 1 and the holes 3 of two insulating boards 2 sandwiching a face, except for a peripheral part 1A of the cover board 1 to rubber rings 6 arranged on the brim face. The peripheral edge parts of terminal metal fitting protruding parts 7 protruded from the insulating boards 2 are pushed/cut in the direction of the outer brims. They are expanded/caulked, and brim parts 10 which are pressure-contacted with the faces of the insulating boards 2 are formed. The rubber rings 6 are tightly sandwiched by the outer brims 4 and the insulating boards 2, and they are compressed. The outer terminal metal fittings 5 are installed on the insulating boards 2 in a closely tight state. The metal fitting protruding parts 7 or the end parts of the outer brims 4 are jointed to the end parts of inner terminal metal fittings 12 installed on a support board 11 by the protection welding part (y) of welding strength, which is detached with a prescribed tension force. Load foils 13a from capacitor elements 13 are connected to the inner terminal metal fittings 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external terminal fitting by displacing a metal cover plate outward by an internal pressure which increases when a capacitor in a case such as an electrolytic capacitor or an MF (metallized film) capacitor is abnormal. The present invention relates to a case-containing capacitor provided with a security mechanism for interrupting conduction with a capacitor element, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a capacitor with a security mechanism of this type, there has hitherto been known a capacitor disclosed in Japanese Utility Model Publication No. 6-39446. In this conventional technique, a metal case in which a capacitor element is stored, a metal upper lid hermetically attached to the periphery of an upper opening of the metal case via an elastic packing, and the metal upper lid are penetrated. A first rivet of a composite type formed by inserting and pressing an aluminum eyelet under the aluminum rivet, and being compressed and sandwiched between the upper resin molded body and the aluminum eyelet. An elastic member for attaching one rivet to the metal lid in an airtight and insulated manner, an external terminal welded to the upper end of the aluminum rivet, and an aluminum foil plate with a weak point welded to the lower end of the aluminum rivet And a resin-molded fixing plate provided with a hole through which the aluminum foil plate with the weak point is inserted, and a second rivet attached to the resin-molded fixing plate. The second rivet, an electrolytic capacitor with a security device having a structure that includes a drawer lead foil plate from the capacitor element fixed connection with the weak parts with aluminum foil plates.

[0003]

In the prior art described above, when an abnormality occurs in the electrolytic capacitor contained in the case, the metal upper lid is greatly deformed so as to bulge upward due to an increase in the pressure in the metal case. With the upward deformation of the metal lid, the first rivet, which is airtightly and insulated from the metal lid, is also displaced upward. The weakened aluminum foil plate with a weak point is pulled upward and cut easily at the weak point. As a result, the connection between the aluminum foil plate with the weak point and the lead foil plate drawn out from the capacitor element is cut off, whereby the electric circuit of the electrolytic capacitor can be cut off.

Therefore, in this conventional example, as shown in FIG. 2 in the prior art publication, the central portion of the metal upper lid is curved round and the external terminal is tilted outward, as shown in FIG. Since the first rivet is tilted to cut the aluminum foil with the weak point, it is good when the external conductor connected to the external terminal is a flexible conductor such as a covered electric wire. In the case of a so-called "board mounting type" capacitor to be mounted in the connection insertion hole of the etc. and used by connecting the projecting part of the external terminal to the conductive land of the printed wiring board by soldering,
As a result of the first rivet not being tilted due to the immovable external terminal, there is also a blind accident in which the aluminum foil plate with the weak point which should be cut when the capacitor is abnormal does not cut, so that this conventional example cannot be used as a board mounted type capacitor. There is a big problem that.

Further, in this conventional example, since the method of fixing the essential part of the first rivet to the upper lid is only press fitting of the eyelet or the hollow rivet by compressing the elastic packing,
If the first rivet is aluminum, which is a soft metal,
The press fitting strength of the eyelet (hollow rivet) to the rivet is small, and the first rivet starts to grind with the compressive restoring resilience of the packing or a small external force. There is an essential problem that the parted aluminum foil is broken or the rivet itself comes off.

Further, in the above conventional example, even if the first rivet is a conductor other than aluminum, the electrolytic solution in the case penetrates by capillary action from the minute gap in the eyelet (or hollow rivet) press-fit portion. The rivet is more likely to come off due to the penetration of the core, the press-fit part of the core is corroded, and the lubricating action of the electrolytic solution. This also has an essential and serious problem that the useful life of the capacitor is short and can be used for only about 5 years at most.

Therefore, in order to eliminate the above-mentioned problems, the present invention is to reinforce the metal cap plate of a case by sandwiching both sides of a central portion of the metal cover plate with an insulating plate, thereby increasing the pressure in the case when the capacitor is abnormal. Then, the cover plate is swelled flat to form a capacitor with a board-mounting type security mechanism, and the external terminal metal is fixed to the cover plate by caulking with the insulating plate in an insulated state. The purpose is to increase the planting strength of the board and to weld the ends of the inner and outer terminal fittings together with the welding parts for security, so that the resistance of the circuit path to the capacitor element can be kept to a minimum for a long time. I do.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for connecting a capacitor between an external terminal and a capacitor element by displacing a metal cover plate outward by an internal pressure which is increased when a capacitor in a case is abnormal. In constructing the case-containing capacitor so as to block off, two holes sandwiching the surface excluding the peripheral surface portion of the lid plate and the hole of the airtight holding ring packing pressed into the hole of the metal lid plate. An external terminal fitting with an outer flange made of extensible metal is inserted into the hole of the insulating plate up to the rubber ring disposed on the flange surface, and the peripheral portion of the terminal fitting protruding portion protruding from the insulating plate is moved in the outer flange direction. By pressing and scraping, spreading and caulking to form a flange portion pressed against the surface of the insulating plate, the rubber ring is tightly sandwiched between the outer flange and the insulating plate and compressed, and the outer terminal fitting is airtightly sealed to the insulating plate. Planting and also said fittings The protruding portion or the end of the outer flange is joined to the end of the internal terminal fitting planted on the support plate by a security welding portion having a welding strength separated by a predetermined tensile force, and the lead foil from the capacitor element is attached to the internal terminal fitting. While connecting, the capacitor element is housed in the case, the peripheral portion of the support plate is fixed to the inner surface of the capacitor case, and the peripheral surface portion of the lid plate is curled into the opening of the case with a rubber packing interposed therebetween. This was achieved by airtight fixing in the department.

The rubber ring may be inserted into the terminal fitting protruding portion, sandwiched between the flange of the terminal fitting which is widened and crimped, and the insulating plate, and may be maintained in compression. May be provided with an outer conductor pressed against the outer collar of the second member.

[0010]

Embodiments of the present invention will be described with reference to the drawings. First, the basic form of the present invention is:
When the capacitor element 13 housed in the bottomed cylindrical metal case 14 as shown in FIG. 1 rises abnormally and the pressure inside the case 14 increases, the metal lid plate 1 such as a round aluminum plate is removed as shown in FIG. In other words, a case-equipped capacitor with a security mechanism is provided, which can be displaced in the direction of FIG. 2 so that conduction between the external terminal fitting 5 and the internal terminal fitting 12 connected to the capacitor element 13 can be cut off as shown in FIG.

In the present invention, a hole of a ring packing 1b press-fitted into a relatively large hole 1a of the metal cover plate 1 is provided.
It is made by lathing or casting with a ductile metal such as aluminum or copper into the holes 3 of two disc-shaped insulating plates 2 sandwiching the upper and lower surfaces of the upper surface of the lid plate 1 except for the peripheral surface portion 1A. As shown in FIG. 3A, the round pin-shaped external terminal fitting 5 with the outer flange 4 is inserted through the outer conductor L disposed on the flange surface thereof to the rubber ring 6.

Next, as shown in FIG. 3, a peripheral portion 7A of the terminal fitting protruding portion 7 protruding from the insulating plate 2 has a vertical hole 8 which is slightly smaller than its plane profile, and is formed only by a predetermined size using a well-known press machine or the like. The order shown in (b), (c), and (d) of FIG. 3 in the direction of the outer flange at the hole edge of the press die 9 which moves strongly and is vertically divided into two and closed in advance. 1, 3 (d) and FIG. 4 (a), which are pressed in the vertical direction, spread over, spread and caulked, and pressed against the surface of the non-circular recess 2a of the insulating plate 2 as shown in FIGS. Thereafter, the pressing die 9 is removed by opening or the like, so that the rubber ring 6 is tightly sandwiched between the outer flange 4 and the insulating plate 2 as shown in each of the above figures and compressed, and the outer terminal fitting 5 is attached to the insulating plate 2. The plant is planted in an airtight state, and the lid plate 1 and the two insulating plates 2 are attached and maintained as shown in FIG.

A well-known ultrasonic welding machine or butt is attached to an end of the internal terminal fitting 12 which is implanted on an insulating support plate 11 made of a hard dish or the like at the end of the fitting projection 7. Well-known welding means such as welding or stud welding
As shown in FIG. 4B, a capacitor element 1 is attached to an end portion 12A of the internal terminal fitting 12 through an outer flange 12a by a welding portion y for security having a welding strength separated by a pulling force of about 15 kg weight.
The lead foil 13a from No. 3 is crushed as shown in FIG.

Next, the capacitor element is housed in the case 14 together with the above-mentioned members in the case 14 as shown in FIG. 1 and a rubber packing 15 disposed on the peripheral surface 1A of the cover plate 1 is wound around the opening of the case 14 by a well-known curling machine, as shown in each of the above drawings. Part 1
4a Compress tightly and fix tightly.

By fixing in a gas-tight manner as described above, the pressure in the case which increases when the capacitor element 13 is abnormal can be
As shown in FIG. 2, the entire inner surface of the peripheral surface portion 1A of the cover plate 1 is displaced outward while being flat, and the welded portion y of the external terminal fitting 5 and the internal terminal fitting 12 is made as shown in FIG. A capacitor in a case provided with a security mechanism according to the present invention, which can be separated vertically and cut off conduction between the metal fittings 5 and 12, can be constructed.

The reference numeral L in each drawing denotes an external conductor for mounting the substrate, and this conductor L is inserted into the metal fitting 5 in advance in contact with the inner surface of the metal fitting outer flange 4. As shown in FIG. 3, the flange 10, which is obtained by spreading and crimping the metal projection 7, is formed below the external terminal metal 5 as described above. Further, the external conductor L may be a pin-shaped external conductor integrally projecting from the outer surface of the outer flange 4 of the metal fitting 5.
1, the outer flange 4 of the metal fitting 5 and the internal terminal fitting 12 may be welded to form a security welded portion y.

Since the present invention employs the above-described embodiment, if electric energy is continuously supplied even after dielectric damage of the capacitor element 13 occurs,
The dielectric material is thermally destroyed in a chain, generating a large amount of heat and decomposition gas, and the internal pressure of the case 14 increases.
(1) Since the gap between the other members in contact with the support plate is applied to the inner surface of the lid plate through a gap, the lid plate 1 is generally flat from the state shown in FIG. 1 to the upper side as shown in FIG. It bulges outward, and the external terminal fitting 5 rises in parallel by an amount corresponding to this bulge amount.

Since the support plate 11 is fixed by the case curl portion 14a via the rubber packing 15 which is always compressed and localized, the inner terminal fitting 12 and the external terminal fitting locked to the support plate 11 by the outer flange 12a. 7-15kg between 5
When a tensile force of about / cm ² or more is applied, the welded portions y of the two are peeled off and cut off, and the supply of electric energy to the capacitor element 13 is cut off. Therefore, it is possible to avoid a dangerous state of burning or explosion of the capacitor due to heat generation in the case, thermal destruction of the dielectric, and filling of the decomposition gas. In such a case, an abnormality occurs in the electric circuit to be used. After confirming the occurrence of the symptom, the defective capacitor may be found by inspection and replaced with a non-defective one.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The outer collar 12 of the inner terminal fitting 12 is described.
In order to connect the aluminum lead foil 13a from the capacitor element 13 to the end 12A passing through the a, a spot welding connection or a screw connection can be adopted. A pressing die (or a fixed die) applied to the lower end of the fitting end 12A below the lead foil 13a inserted through the fitting end 12A in the state of FIG. 4 (b) and the peripheral surface of the metal cover plate By making the relative distance between the fixed die (or the pressing die) applied to the upper surface of the external terminal fitting 1A or the external terminal fitting 5 close to the predetermined distance by a well-known means, the rigidity of the internal terminal fitting 12 via the hard support plate 11 is reduced. Crush the end 12A passing through the outer collar 12a,
The caulking flange 12B can be formed, and the lead foil 13a can be tightly crimped to the metal fitting end 12A as shown in FIG. 4C.

However, when the die is applied to the peripheral surface 1A of the cover plate and the end 12A of the metal fitting is crushed and crimped by the pressing pressure applied through the support plate 11, the die is applied to the external terminal metal fitting 5 and caulked. Unnecessary caulking stress applied to the welded portion y between the inner and outer terminal fittings is smaller than in the example.

The method of welding the welding portion y is as follows. The welding electrode of the butt welding machine is attached to the ground end of each of the metal fittings 5 and 12 in a state where the welded ends of the inner and outer terminal fittings 5 and 12 are lightly in contact with each other. The metal fittings 5 and 12 are pressed strongly while applying a current of about 1 kA between the electrodes at a voltage of 1.6 volts for about 0.8 seconds, and the metal fittings 5 and 12 are welded to each other at a welding portion y. Can be connected, and when a tensile stress of about 10 kg weight is applied to both metal fittings 5 and 12, the welded portion y is separated,
It turned out that it can be practically used.

Further, according to the present invention, the rubber ring 6 is provided on the protruding portion 7 of the external terminal fitting 5 protruding from the surface of the insulating plate 2.
The rubber ring 6 is press-fitted against the insulating plate 2 by the flange 10 formed by expanding and crimping, so that the airtightness between the external terminal fitting 5 and the insulating plate 2 is ensured. It may be. In this example, the portions indicated by the reference numerals in FIG. 4 indicate the same or the same portions as the same reference numerals in FIG.

[0023]

The present invention adopts the above-described embodiment, and has the following effects. Capacitor element 1
If the supply of electric energy is continued even after the dielectric damage of the dielectric material 3 occurs, the dielectric material is thermally broken down in a chain, generating a large amount of heat and decomposition gas, and the internal pressure of the case 14 increases. This pressure passes through the gap around the support plate 11 and the cover plate 1
, The cover plate 1 bulges upward and outward in a substantially flat state as a whole, and the external terminal fittings 5 rise in parallel by an amount corresponding to the bulge amount.

Since the support plate 11 is fixed at the case curl portion 14a via the rubber packing 15 which is always compressed and localized, the internal terminal fitting 12 and the external terminal fitting secured to the support plate 11 by the outer flange 12a. 7-15kg between 5
When a tensile force of about / cm ² or more was applied, the welded portions y of the two were peeled off and cut off, and the supply of electric energy to the capacitor element 13 could be cut off.

Therefore, according to the present invention, most of the case-covered capacitor except for the peripheral portion of the metal cover plate 1 is sandwiched and reinforced by the insulating plate 2, so that when the capacitor is abnormal, the pressure inside the case is increased. The board 1 can be swelled flat to provide a board-mounted capacitor with a security mechanism, and the external terminal fittings 5 can be connected to the cover plate 1 by the insulating plate 2.
By fixing the terminal in an insulated state, the planting strength of the terminal fitting with respect to the insulating plate can be increased,
Further, since the ends of the inner and outer terminal fittings are welded to each other by the welding portion y for security, there are three effects that the resistance of the electric circuit to the capacitor element can be kept extremely small for a long time.

In particular, the external terminal fitting 5 of the present invention
Since the peripheral portion 7A of the protruding portion 7 is pressed against the insulating plate 2 and crimped and implanted with the flange portion 10 which is spread, the both ends of the metal fitting 5 serving as the essential welding portion y are formed with the caulking. It can be welded to the end face of the internal terminal fitting 12 without any variation with accurate welding strength without causing any damage or deformation, and a reliable light-shielding action and security effect can be obtained.

According to the third and fourth aspects of the present invention, in addition to the above-mentioned effects, since the external terminal L is provided with the external conductor L, the external conductor L can be directly printed as it is. It can be attached to a connection hole such as a through-hole in a wiring board, and has the added effect that it can be used as a so-called "board mounting type" capacitor by connecting the projecting part of the external terminal to the conductive land of the printed wiring board by soldering did it.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing an example of an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view in a state different from FIG. 1;

FIG. 3 is a process sectional view of an example in which external terminal fittings are hermetically planted on an insulating plate.

FIG. 4 is an essential part cross-sectional view showing an example of an assembling order of the one shown in FIG.

FIG. 5 is a sectional view of a main part showing another example in which external terminal fittings are hermetically planted on an insulating plate.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 metal cover plate 1a hole in metal cover plate 1b ring packing for keeping airtight pressed into hole in metal cover plate 1A peripheral portion of metal cover plate 2 insulating plate 3 insulating plate hole 4 outer flange 5 external terminal fitting Reference Signs List 6 Rubber ring 7 Metal projection protruding from insulating plate 7A Peripheral edge of metal projection protruding from insulating plate 8 Vertical hole of push die 9 Push die 10 Collar formed by crimping 11 Support plate 12 Internal terminal fitting 13 Capacitor element 13a Lead foil 14 Case 14a Curl part 15 Packing y Security welding part

Claims (6)

[Claims] 1. A case-containing capacitor in which a metal cover plate is displaced outward by an internal pressure that increases when the case-containing capacitor is abnormal to interrupt conduction between external terminal fittings and the capacitor element. Ring packing 1b for keeping airtight pressed into hole 1a of metal lid plate 1.
And an external terminal fitting 5 with an outer flange 4 made of extensible metal on the flange surface of the cover plate 1 and the holes 3 of the two insulating plates 2 sandwiching the surface excluding the peripheral surface portion 1A of the cover plate 1. The peripheral portion 7A of the terminal fitting protruding portion 7 protruding from the insulating plate 2 is inserted through the rubber ring 6 and the vertical hole 8 slightly smaller than its planar contour.
The rubber ring 6 is pressed against the surface of the insulating plate 2 by pressing and shaping in the direction of the outer flange at the hole edge of the pressing die 9 having
Then, the outer terminal fitting 5 is implanted in the insulating plate 2 in an airtight state, and the lid plate 1 and the insulating plate 2 are attached and maintained. Is bonded to the end of the internal terminal fitting 12 implanted in the support plate 11 at a welding portion y having a welding strength separated by a predetermined tensile force, and a lead foil 13a from the capacitor element 13 is connected to the internal terminal fitting 12, The capacitor element is housed in the case 14 and the peripheral portion of the support plate 11 is
And the peripheral surface 1A of the lid plate 1 is hermetically fixed to the opening of the case 14 with a curl portion 14a with a rubber packing 15 interposed therebetween. The external terminal fitting 5 and the internal terminal fitting 1 are displaced outward by pressure.
A case-equipped capacitor provided with a security mechanism for separating the welded portion y from the second and interrupting conduction. 2. The case-containing capacitor according to claim 1, wherein the metal cover plate is displaced outward by an internal pressure that is increased when the case-containing capacitor is abnormal, so that conduction between the external terminal fitting and the capacitor element is cut off. Ring packing 1b for keeping airtight pressed into hole 1a of metal lid plate 1.
And an external terminal fitting 5 with an outer flange 4 made of extensible metal in the hole 3 and the holes 3 of the two insulating plates 2 sandwiching the surface excluding the peripheral surface 1A of the lid plate 1 to the flange surface. Insert the insulating plate 2
A rubber ring 6 is inserted into a terminal fitting protruding portion 7 protruding from the outer peripheral portion 7A of the protruding portion 7 and is pushed in the outer flange direction by a hole edge of a pressing die 9 having a vertical hole 8 which is slightly smaller than its plane profile. The rubber ring 7 is formed into a flange portion 10 pressed against the surface of the insulating plate 2 by shaving and spreading and caulking, so that the outer terminal fitting 5 is implanted in the insulating plate 2 in an airtight state and is insulated from the cover plate 1. The internal terminal fitting 1 which is attached to the plate 2 and maintained, and the end of the external terminal fitting 5 is planted on the support plate 11.
The internal terminal fitting 12 is connected to the lead foil 13a from the capacitor element 13 while being joined to the end portion 2 at a welding portion y having a welding strength that is separated by a predetermined tensile force. The periphery of the support plate 11 is fixed to the inner surface of the capacitor case 14 and the cover plate 1
The peripheral surface 1A is hermetically fixed to the opening of the case 14 with a curl portion 14a sandwiching a rubber packing 15, and the cover plate 1 is displaced outward due to a pressure inside the case that increases when the capacitor element 13 is abnormal. A cased capacitor provided with a security mechanism for separating the welded portion y between the external terminal fitting 5 and the internal terminal fitting 12 to cut off conduction. 3. An external conductor L for mounting a printed wiring board between an outer flange 4 (10) of an external terminal fitting 5 and a rubber ring 6.
A cased capacitor provided with a security mechanism according to claim 1, wherein said capacitor is fixedly supported. 4. A case equipped with a security mechanism according to claim 2, wherein an external conductor L for mounting a printed wiring board is sandwiched and fixed between the outer flange 4 (10) of the external terminal fitting 5 and the insulating plate 2. Capacitors. 5. A case-containing capacitor, wherein the metal cover plate is displaced outward by an internal pressure that increases when the case-containing capacitor is abnormal, whereby conduction between the external terminal fitting and the capacitor element is cut off. External terminal fittings with outer collar made of extensible metal in the hole of the ring packing pressed into the hole of the metal lid plate and the hole of two insulating plates sandwiching the surface excluding the peripheral surface of this lid plate Through the rubber ring disposed on the flange surface, and push the peripheral portion of the terminal fitting protruding portion protruding from the insulating plate in the outer flange direction with a hole edge of a pressing die having a vertical hole slightly smaller than its plane contour. By shaving and spreading and caulking to form a flange portion pressed against the surface of the insulating plate, the rubber ring is tightly sandwiched between the outer flange and the insulating plate and compressed, and an outer terminal fitting is implanted on the insulating plate in an airtight state. And the lid The plate and the insulating plate are attached and maintained.
The end of the metal fitting is joined to the end of the internal terminal fitting implanted on the support plate at a welding portion having a welding strength that is separated by a predetermined tensile force, and a lead foil from a capacitor element is connected to the internal terminal fitting. The capacitor element is housed in the case, the peripheral edge of the support plate is fixed to the inner surface of the capacitor case, and the peripheral surface of the lid plate is air-tightly fixed to the opening of the case with the curl portion between rubber packings. Become
A case-containing capacitor provided with a security mechanism for displacing the cover plate outward by the case internal pressure that increases when the capacitor element is abnormal and separating the welded portion between the external terminal fitting and the internal terminal fitting to cut off conduction. Manufacturing method. 6. A case-containing capacitor in which a metal cover plate is displaced outward by an internal pressure that increases when the case-containing capacitor is abnormal to interrupt conduction between external terminal fittings and the capacitor element. External terminal fittings with outer collar made of extensible metal in the hole of the ring packing pressed into the hole of the metal lid plate and the hole of two insulating plates sandwiching the surface excluding the peripheral surface of this lid plate To the flange surface, a rubber ring is inserted into the terminal fitting protruding portion protruding from the insulating plate, and the peripheral portion of this protruding portion is formed with a hole edge of a push die having a vertical hole slightly smaller than its plane contour. By pressing and shaving in the direction of the outer flange and spreading and caulking to form the rubber ring as a flange pressed against the surface of the insulating plate, an outer terminal fitting is implanted on the insulating plate in an airtight state, and the lid plate and the insulating plate And maintain coalescence Further, the end of the metal fitting is joined to the end of the internal terminal fitting implanted on the support plate at a welding portion having a welding strength separated by a predetermined pulling force, and a lead foil from a capacitor element is connected to the internal terminal fitting. The capacitor element is housed in a case, the peripheral edge of the support plate is fixed to the inner surface of the capacitor case, and the peripheral surface of the lid plate is hermetically sealed in the opening of the case by a curl portion with a rubber packing interposed therebetween. A security mechanism that is fixed and displaces the lid plate outward by the internal pressure of the case that increases when the capacitor element is abnormal to separate the welded portion between the external terminal fitting and the internal terminal fitting to interrupt conduction. Method for manufacturing a capacitor with a case.