JPH05251266A - Film capacitor and metallized film thereof - Google Patents

Abstract

PURPOSE:To enable a fuse inside a film capacitor to function stably. CONSTITUTION:A metal evaporation film 3 is formed on the upper side of a film base material 4 along one side edge, excluding a margin non-evaporation section 4A, and a fuse non-evaporation section 20 is intermittently formed away from the other side edge at a certain distance, and fuses 21 of certain width are formed at gaps respectively, and furthermore a region dividing non- evaporation section 11 extending in a crosswise direction of the film base material 4 is provided so as to reach the margin non-evaporation part 4A extending from the fuse non-evaporation part 20. Each of the lengthwise side edges 20A of the fuse non-evaporation part 20 is formed into a circular arc shape protruding toward the adjacent fuse 21, whereby the width of the center of the fuse 21 is set smaller than those of its ends.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metallized film capacitor and a metallized film for manufacturing the same.

[0002]

2. Description of the Related Art A metallized film capacitor of this type is usually manufactured through the following steps. First, as shown in FIG. 5, a metal such as aluminum or zinc is formed on the upper surface of the dielectric film base material 4 having a constant width and long, except for the non-deposition portion 4A for margin having a constant width along one side edge thereof. The vapor-deposited film 3 is formed, and the first metallized film 1 is formed.
And

Next, like the metallized film 1, a second metallized film 2 is formed by forming a metal vapor deposition film 5 on the upper surface of the dielectric film base material 6 except for the margin non-evaporated portion 6A. Margin non-deposited parts 4A, 6A
Are located on opposite sides of each other, and the non-deposited portions 4A and 6A are superposed on the first metallized film so as to be located inward of the edge of the other film.

Further, after winding the laminated film (1 + 2) into a cylindrical shape, electrodes 8 such as zinc and solder are formed on both ends of the cylindrical body 7 by a spraying method or the like as shown in FIG. A lead wire 9 is connected to each electrode 8 and the whole is covered with an exterior 10 to complete the product.

By the way, in an AC circuit for electric equipment or the like, a safety device may be provided in order to prevent equipment damage and fire accident due to abnormality of a capacitor, and as a safety device of this kind, it is generally operated by an abnormal current. Electric fuses, temperature fuses that utilize temperature rise, pressure fuses that utilize deformation of the lid of a capacitor case, and the like are used.

However, each of the above fuses has a drawback that the response speed is not sufficient and it takes a certain time to operate. It has also been proposed to incorporate the above-mentioned fuse function inside the capacitor.However, the strength of the capacitor case is restricted, which makes it difficult to design the capacitor. However, it has a drawback that it is costly.

Therefore, recently, measures to improve the above-mentioned drawbacks by providing a fuse function in the metallized film for capacitors themselves have begun to be taken. FIG. 7 shows an example of such a metallized film with a fuse. This metallized film is used as one of the metallized films 1 (or 2) in FIG. 5, and the metal vapor-deposited film 3 (or 5) has a non-deposition portion for division 11 extending in the width direction. The formed metal vapor deposition film 3 is divided into a large number of rectangular portions 3A.

To form such a non-deposited portion 11,
After spraying oil on the corresponding part of the film substrate 4,
A method of locally preventing the vapor deposition by performing vapor deposition, a method of removing the vapor deposition film by laser light, or the like is possible.

When the metallized film of FIG. 7 is used, when a short circuit occurs between the metal vapor deposition films 3 and 5, the junction P1 between the rectangular portion 3A including the short-circuited portion and the electrode 8 generates heat and disconnects as a fuse. The power supply to the short-circuited location is stopped.

However, in the above fuse structure,
It is difficult to accurately adjust the contact resistance between the rectangular portion 3A and the electrode 8 and the fuse action tends to vary.

FIG. 8 shows a metallized film in which the above-mentioned drawbacks have been improved. In this film, a non-deposited fuse is formed which extends in the longitudinal direction of the film at a position spaced apart from the edge of the film on the side opposite to the non-deposited portion 4 for the margin. It is characterized in that the portion 12 is formed intermittently, and the division non-deposition portion 11 that extends from the fuse non-deposition portion 12 to the margin non-deposition portion 4 is formed. The fuse non-deposited portion 12 manufactured so far has a longitudinal end formed in a U shape as shown in FIG. 9, and the fuse portion 13 has a rectangular shape.

In this example, the gap between the fuse non-deposited portions 12 is the fuse portion 13, and the metal vapor deposition films 3 and 5 are provided.
When a short circuit occurs, the rectangular portion 3A including the short circuit portion
The fuse portion 13 connected to is disconnected from the fuse due to heat generation, and the power supply to the short-circuited portion is stopped. According to this example, the fuse unit 1
By setting the width of 3 as appropriate, there is an advantage that the energization amount to the fuse portion 13 can be freely set.

[0013]

However, as a result of various safety tests regarding the fuse action of FIG. 9, the present inventors have confirmed that the fuse action still varies. A detailed study of the cause has revealed that the cause is the shape of the fuse portion 13.

That is, since the fuse portion 13 has a rectangular shape with a constant width, when the excess current flows, the entire fuse portion 13 first generates heat (hatched portion in FIG. 9), and the metal in the heat generating portion evaporates. Evaporation starts selectively from the easy part. Once evaporation occurs, heat is concentrated in the narrowed portion, and the fuse portion 13 is blown at once. In this process, the influence of a slight wall thickness error, a slight width error, etc. of the fuse portion 13 is magnified, which causes a deviation at the start of evaporation, so that a relatively large variation occurs in the current value leading to the fuse cutting. This leads to instability of the fuse action.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a film capacitor and a metallized film for a capacitor which can obtain a stable fuse action.

[0016]

In order to solve the above-mentioned problems, the metallized film for capacitors of the present invention has a constant width and a constant width along one side edge on the upper surface of a long plastic film substrate. A metal vapor-deposited film is formed excluding the margin non-vapor-deposited portion, and a non-vapor-deposited portion for fuse that extends in the longitudinal direction of the film substrate is intermittently formed on the metal vapor-deposited film at a position apart from the other side edge of the film by a certain distance. To form a fuse portion having a constant width in the gap between the fuse non-deposited portions, further, in the metal vapor deposition film, extending in the width direction of the film substrate, at least from the fuse non-deposited portion In a metallized film for a capacitor, which is formed with a non-evaporated portion for area division reaching a non-evaporated portion for a margin, both edges of the fuse non-evaporated portion in the longitudinal direction of the film. By forming into a shape tapering toward the adjacent fuse unit, characterized in that the width of the center portion of the fuse unit is smaller than the width of both ends.

Both end edges of the fuse non-deposited portion in the longitudinal direction of the film may have a semicircular arc shape or a semielliptic arc shape. Further, the metal vapor deposition film may be formed of one or more metals selected from aluminum, zinc, copper or alloys thereof. Furthermore, the film base material may be selected from polyethylene terephthalate, polypropylene, polystyrene, polycarbonate, polytetrafluoroethylene, and polyethylene.

On the other hand, in the film capacitor of the present invention, one of the above-mentioned film for capacitor production is used as the first film, and the plastic film substrate having the same width and the same length as the film substrate of the first film. On the upper surface of
The second film on which the metal vapor deposition film is formed except for the margin non-deposited portion having a constant width along one of the side edges is a non-deposited portion for fuse of the first film. In order that the non-deposited portion for margin of the first film corresponds to the metal evaporated film of the second film, it is superposed on the first film and wound, and electrodes are respectively connected to both ends of this cylindrical body. Thus, each electrode is connected to the metal vapor deposition film of each film.

[0019]

According to the film capacitor and the metallized film for capacitors of the present invention, since the shape of the fuse portion is such that the width of the central portion is narrower than that of both ends, the fuse having a relatively high electric resistance when an excess current flows. The central part of the part heats up intensively, and evaporation surely starts from this central part. Therefore, the influence of a slight wall thickness error or a slight dimensional error of the fuse portion on the critical current value at which the fuse portion is broken is small, the variation in the critical current value is small, and a stable fuse action can be obtained.

[0020]

EXAMPLES Examples of the film capacitors and metallized films for capacitors according to the present invention will be described in detail below. FIGS. 1 and 2 are views showing an embodiment of a metallized film. Reference numeral 4 is a long plastic film substrate having a constant width, and 3 is a metal vapor deposition film 3 formed on the upper surface of the film substrate 4. is there.

The metal vapor-deposited film 3 is separated from the marginal non-deposited portion 4A extending along the longitudinal direction of the film with a constant width along one side edge of the film substrate 4 and the other side edge of the film substrate 4 by a certain distance. A non-deposited portion for fuse 20 that extends intermittently in the longitudinal direction of the film at a different position, and a non-deposited portion for region division 11 that extends in the film width direction and reaches the non-deposited portion for margin 4A from the fuse non-deposited portion 20. It is formed over the entire upper surface of the film base material 4, except for.

The plastic used as the material of the film base material 4 is not limited, but preferably, one kind or two or more kinds selected from polyethylene terephthalate, polypropylene, polystyrene, polycarbonate, polytetrafluoroethylene and polyethylene is laminated. Preferably, the thickness is set according to need.

The metal vapor deposition film 3 is preferably formed of one or more metals selected from aluminum, zinc, copper or alloys thereof, and the thickness thereof is appropriately set as necessary. It If the metal vapor deposition film 3 is made of the above metal, the manufacturing cost is relatively low, and good capacitor performance and fuse performance can be obtained.

The main feature of this embodiment is that both ends 20A of the fuse non-deposited portion 20 in the longitudinal direction of the film are formed in a semi-circular shape, so that the width W2 at the center of the fuse portion 21 is at both ends. It is smaller than the width of the section. That is, the radius of curvature R of the both end edges 20A is 1/2 of the width W1 of the fuse non-deposition portion 20. Although the value of the width W1 is not limited, it is generally 0.
The width W2 of the fuse portion 21 is preferably about 0.1 to 2.0 mm.

However, the present invention is not limited to the illustrated example, and both end edges 20A of the fuse non-deposition portion 20 in the longitudinal direction of the film may be formed in an elliptical shape or a triangular shape. That is, it suffices that the width of the central portion of the fuse portion 21 is smaller than the width of both end portions.

Further, in the figure, 1 of the non-evaporated portion 20 for fuse is shown.
The region dividing non-deposited portions 11 are formed every other space, and the two fuse portions 21 are formed for each rectangular portion 3A, but the present invention is not limited to this. May be changed arbitrarily.

In order to manufacture the metallized film as described above, for example, each non-deposited portion 20, of the film base material 4,
It is also possible to spray oil on a portion corresponding to 11 and then perform vapor deposition on a portion excluding the margin non-vapor deposition portion 4A to locally prevent vapor deposition, but the non-vapor deposition portion can be more accurately configured. Laser light may be used for formation.

The manufacturing method using laser light is performed as follows, for example. A wide non-cutting film base material 4 is continuously run in a vacuum container, and the margin non-deposition portion 4
After forming the metal vapor deposition film 3 on the portion excluding A, a portion having a diameter equal to the width of the non-vapor deposition portions 11 and 20 is formed on the portion of the metal vapor deposition film 3 where the non-vapor deposition portions 11 and 20 are to be formed. The circularly focused laser light is emitted (see reference numeral 22 in FIG. 2).

As a result, the metal vapor deposition film 3 at the irradiated portion is evaporated and the film base material 4 is exposed. Next, the wide film substrate 4 is slittered to be cut into a plurality of strips,
Each may be wound up into a metallized film.

Next, an example of a film capacitor using the above metallized film will be described. FIG. 3 is a cross-sectional view showing an example thereof, reference numeral 1 is the metallized film (first film) described above, and reference numeral 2 is the second film.

The second film 2 is formed on the upper surface of a plastic film base 6 having the same width and the same length as the film base 4, except for a margin non-deposited portion 6A having a constant width along one side edge thereof. The metal vapor deposition film 5 is formed, and the first
It does not have a non-deposited portion for fuse and a non-deposited portion for margin like the film 1. The margin non-deposition portion 6A is normally set to have the same width as the margin non-deposition portion 4A.
The values do not necessarily have to be the same, and the values may be changed slightly.

According to the film capacitor and the metallized film for capacitors having the above-mentioned structure, since the shape of the fuse portion 21 is a drum shape in which the width of the central portion is narrower than that of both ends, the electric resistance is relatively increased when an excess current flows. The central portion of the high fuse portion 21 generates heat intensively, and the central portion quickly evaporates. Therefore, the fuse portion 21
The influence of a slight wall thickness error, a slight dimensional error, etc. of the fuse portion 21 on the critical current value at which
There is little variation in the critical current value, and a stable fuse action can be obtained.

[0033]

[Experimental Example] Next, the effect of the present invention will be demonstrated with reference to an experimental example. Using a polyethylene terephthalate film having a thickness of 4.8 μm, a capacitor production film of the present invention as shown in FIG. 1 (experimental example) and a conventional capacitor production film as shown in FIG. 8 (comparative example) are produced. did.

The common dimensions of the experimental example and the comparative example are as follows. Film width: 30 mm Width of margin non-deposition portion 4A: 1.5 mm Fuse non-deposition portion 20 and area division non-deposition portion 11
Width: 0.5 mm Evaporated metal: Aluminum Evaporation amount: Area resistance value 3.5 ohm / cm ^{2 In the} experimental example, both ends of the fuse non-evaporated portion 20 have a semicircular shape with a radius of curvature of 0.5 mm, while comparing In the example, only the rectangular shape is different.

Film capacitors were prepared in exactly the same manner by using the obtained films of the experimental example and the comparative example, and JIS-C was applied to each of the obtained capacitors.
The security test specified in 4908 was performed. This safety test was carried out by the following procedure by connecting the circuit shown in FIG. 4 to the capacitor Cx while keeping the temperature constant by putting the capacitor in a constant temperature bath capable of forcibly cooling to ± 3 ° C.

With the switch S in the open position, a voltage 1.3 times the rated voltage having a waveform close to a sine wave of 50 Hz is applied to the capacitor Cx. Switching the switch S to the terminal b, the discharge capacitor C
A DC voltage 7 times the rated voltage of the capacitor Cx is applied to o. The capacity of Co is twice that of Cx. When the discharging capacitor Co is charged, the switch S is switched to the terminal a, and the electric charge of Co is discharged to Cx to which an AC voltage 1.3 times the rated voltage is applied. After discharging, the switch S is returned to the terminal b again, and the same operation is repeated thereafter. The discharge frequency at this time is once every 15 seconds. The current value is recorded by an alternating current ammeter, and when the alternating current flowing through Cx becomes almost 0, this test is terminated and the number of cycles is recorded. The results of the above-mentioned security test are shown in Table 1.

[0037]

[Table 1]

As is clear from Table 1, the number of cycles of the 10 capacitors prepared using the film of the experimental example was in the range of 476 to 593, while the number of cycles was 205 to 981 in the film of the comparative example. The values fluctuated greatly.

[0039]

As described above, according to the metallized film capacitor of the present invention, the shape of the fuse portion is such that the width of the central portion thereof is narrower than that of the both end portions thereof, so that when an excess current flows, it is relatively Further, the central portion of the fuse portion having a high electric resistance intensively generates heat, and the evaporation surely starts from this central portion. Therefore, the influence of a slight wall thickness error or a slight dimensional error of the fuse portion on the critical current value at which the fuse portion is broken is small, the variation in the critical current value is small, and a stable fuse action can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a film for producing a capacitor according to the present invention.

FIG. 2 is an enlarged view of a fuse portion of the capacitor manufacturing film.

FIG. 3 is a sectional view of an essential part of a capacitor using the film for manufacturing the same capacitor.

FIG. 4 is a circuit diagram showing a circuit used for a security test.

FIG. 5 is a sectional view of a main part of a conventional film capacitor.

FIG. 6 is a plan view of a conventional film capacitor.

FIG. 7 is a plan view of a conventional capacitor manufacturing film.

FIG. 8 is a plan view of a conventional capacitor manufacturing film.

FIG. 9 is an enlarged view of a fuse portion of a conventional capacitor manufacturing film.

[Explanation of symbols]

 1 Capacitor Manufacturing Film (First Film) 2 Second Film 3,5 Metal Evaporation Film 3A Divided Part 3B Electrode Connection Part 4,6 Film Base Material 4A, 6A Margin Non-Evaporated Part 11 Area Divided Non-Evaporated Part 20 Fuse Non-deposited part for fuses 20A Both edges of fuse part 21 Fuse part

Claims (5)

[Claims] 1. A metal vapor-deposited film is formed on the upper surface of a plastic film base material having a constant width and a long width, except for a non-deposited portion for margin having a constant width along one side edge thereof. By intermittently forming a fuse non-deposited portion that extends in the longitudinal direction of the film base material at a position apart from the other side edge of the film by a certain distance, a fuse of a constant width is provided in the gap between the fuse non-deposited portions. Each part,
Furthermore, in the metallized film for a capacitor, which is formed on the metal vapor deposition film in the width direction of the film base material, and at least a region division non-evaporation part reaching from the fuse non-evaporation part to the margin non-evaporation part is formed. The width of the central portion of the fuse portion is made smaller than the width of both ends of the fuse portion by forming both end edges of the non-evaporated portion in the longitudinal direction of the film in a convex shape toward the adjacent fuse portion. A metallized film for capacitors. 2. The metallized film for capacitors according to claim 1, wherein both end edges of the fuse non-deposited portion in the longitudinal direction of the film have a semi-arc shape or a semi-elliptical arc shape. 3. The metal deposition film is made of aluminum, zinc,
The metallized film for capacitors according to claim 1 or 2, which is formed of one kind or two or more kinds of metals selected from copper or alloys thereof. 4. The film base material is formed of one or more plastics selected from polyethylene terephthalate, polypropylene, polystyrene, polycarbonate, polytetrafluoroethylene, and polyethylene. Item 7. A metallized film for capacitors according to item 1, 2 or 3. 5. A plastic film base material having the same width and the same length as the film base material of the first film, while the capacitor manufacturing film according to claim 1, 2, 3 or 4 is used as a first film. A second film having a metal vapor-deposited film formed on the upper surface except a margin non-deposited portion having a constant width along one side edge of the second film, and the margin non-deposited portion of the second film is used for the fuse of the first film. The laminated film is superposed on the first film so as to correspond to the non-vapor-deposited portion, and the non-vapor-deposited portion for margin of the first film corresponds to the metal vapor-deposited film of the second film, and then the laminated film is wound into a cylindrical shape,
A film capacitor, characterized in that electrodes are connected to both ends of the columnar body to connect these electrodes to the respective metal vapor deposition films.