JPH05326322A - Metallized film capacitor - Google Patents

Abstract

PURPOSE:To improve the moisture resistance without exposing an electrode by providing a longitudinal insulating groove at one side margin of a dielectric film and providing a plurality of lateral insulating grooves leading to the longitudinal groove so as to constitute a metallized film including electrodes. CONSTITUTION:An electrode 2 is formed at one side of a dielectric film 1 by depositing metal, leaving the insulating groove 3 provided longitudinally at one side margin. And, separately from the insulating groove 3, a plurality of lateral grooves 3 leading to the said longitudinal grooves 3 are provided to separate the electrode 2 into the shape of a plurality of islands lined up in longitudinal direction. Then, two sheets of these metallized films 5 are put on top of each other, and they are rolled to constitute a capacitor element 6. And, an electrode lead section 7 is formed by flame-coating metallicon metal to both sides of the capacitor element 6, and a lead wire 8 is connected to this. Hereby, even if the safety function works, and gas arises, and inner pressure rises, thermosetting resin for armor expands corresponding to it, so it never causes cracks.

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 in which a capacitor element formed by winding a metallized film formed by vapor deposition of metal electrodes on the surface of a dielectric film is coated with a thermosetting resin. It is a thing.

[0002]

2. Description of the Related Art Conventionally, a metallized film capacitor of this type is provided with an insulating groove in the width direction on one side or both sides of a dielectric film to form an electrode by vapor-depositing a metal, and the electrode has a long dielectric film length. A metallized film is obtained by providing a plurality of insulating grooves in the length direction so as to be separated into a plurality of islands in the depth direction.

Then, two of the above metallized films are superposed and wound, and metallicon metal is sprayed on both end faces of the wound metallized film to form electrode lead-out portions, and lead wires are welded to the electrode lead-out portions. To form a capacitor element.

Then, a metallized film capacitor was manufactured by coating the above capacitor element with a thermosetting resin having a glass transition point of 95 ° C. or more and an elongation of 2% or less at 25 ° C.

[0005]

However, the above metallized film capacitor uses a metallized film having a safety function in which a plurality of island electrodes are formed in the length direction of the dielectric film. The thermosetting resin coated with a capacitor element formed by winding the metallized film has a glass transition point of 95 ° C. or higher and an elongation of 2% or less at 25 ° C.

For this reason, during a safety function operation test and during use of the metallized film capacitor, if a part of the metallized film breaks due to some abnormality, gas is generated and the internal pressure rises, resulting in damage to the capacitor. As a result, the exterior resin may be cracked or the exterior resin may scatter,
Finally, there were drawbacks such as smoking and ignition.

[0007]

SUMMARY OF THE INVENTION The present invention seeks to provide a metallized film capacitor which overcomes the above disadvantages. That is, an insulating groove is provided on one side or both sides of the dielectric film in the widthwise edge portion to form an electrode by vapor-depositing a metal, and the electrode is formed into a plurality of islands or a plurality of islands in the length direction of the dielectric film. A metallized film is formed by providing a plurality of lengthwise insulating grooves connected to the insulating grooves so as to be formed in a peninsular shape.

Two metallized films are superposed and wound to form a capacitor element, which has a glass transition point of 65 to 100 ° C. and an elongation of 25 ° C. of 3 to 8
% Metallized film capacitor, which is coated with a thermosetting resin having a property of%.

[0009]

With the above structure, a part of the metallized film causes a breakage phenomenon due to some abnormality during use, and the breakage current concentrates at the breakage point from the power source through the electrode lead-out portion and the electrode contact portion. At this time, since the mechanical contact portion between the electrode lead-out portion and the electrode has a certain electric contact resistance, Joule heat is generated when the breakdown current passes through the contact portion, and the vicinity of the contact portion is generated. The electrode metal film of is evaporated and scattered.

If a part of the electrode metal film in the contact portion is scattered and loses electrical continuity, the density of the current flowing through the remaining conductive contact portion increases, and further large Joule heat is generated, so that it remains. Scattering of the electrode metal film near the conductive contact part accelerates, and eventually the electrode including the break point is completely insulated from the capacitor body and the current to the break point is cut off, causing smoke and ignition. Does not reach.

As a result of further examination of the metallized film capacitor having a structure in which the capacitor element according to the present invention is covered with a thermosetting resin, as a result, in order to fully exhibit the safety function, the safety function is required. The capacitor element has a glass transition point of 65 to 100 ° C and an elongation of 25.
It has been found that coating and coating with a thermosetting resin having a property of 3 to 8% at 0 ° C. may be performed.

When the safety function of the capacitor operates,
Although gas is generated and the internal pressure rises, it is safe by coating with a thermosetting resin that has a glass transition point of 65 to 100 ° C and an elongation of 25 ° C of 3 to 8%. The thermosetting resin expands with respect to the gas of the capacitor generated at the time of function operation, and the safety function can be operated without causing package cracks or scattering.

[0013]

1 is a perspective view showing an essential part of a metallized film capacitor according to the present invention, in which a metal film is left on one surface of a dielectric film 1 and leaving an insulating groove 3 provided at an end portion in the width direction thereof. The electrode 2 is formed by vapor deposition, and the electrode 2 is formed separately from the insulating groove 3.
Of the metallized film 5 provided with the insulating groove 4 connected to the insulating groove 3 so as to divide the dielectric film 1 into a plurality of rectangular islands in the length direction of the dielectric film 1. The electrode lead-out portion 7 is formed by spraying metallikon metal on both end faces of the capacitor element 6, and the lead wire 8 is connected to the electrode lead-out portion 7.

A metallized film capacitor was manufactured by coating the capacitor element 6 constructed as described above with a thermosetting resin 10 having a glass transition point of 65 to 100 ° C. and an elongation of 3 to 8%. Therefore, even if a destruction phenomenon occurs in a part of the electrode 2 of the metallized film capacitor, it does not spread to the whole and it is possible to prevent an accident such as smoke and ignition.

With the above structure, a part of the metallized film 5 may be destroyed due to some abnormality during use,
The breakdown current concentrates from the power source at the breakdown location via the electrode lead-out portion 7 and the contact portion 9 of the electrode 2. At this time, since the mechanical contact portion 9 between the electrode lead-out portion 7 and the electrode 2 has a certain electric contact resistance, Joule heat is generated when the breakdown current passes through the contact portion 9. , The contact portion 9 as shown in FIG.
The electrode metal film in the vicinity causes evaporation and scattering.

If a part of the electrode metal film of the contact portion 9 scatters and loses electrical continuity, the density of the current flowing through the remaining conductive contact portion 9 increases and a larger Joule heat is generated. The remaining electrode metal film near the contact portion 9 having conductivity progresses at an accelerating rate, and finally the electrode 2 including the destruction portion is completely insulated from the capacitor body and the current to the destruction point is cut off. No smoke or fire.

Further, Table 1 shows a capacitance of 8 μF according to the present invention,
A glass transition point of 40 ° C, 50 ° C, 55 ° C, 60 ° C, 65 ° C, 70
℃, 73 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95
Elongation at 2 ℃ at 25 ℃, 100 ℃, 105 ℃
%, 3%, 3.5%, 4.5%, 5.5%, 6%, 7
The results of a safety test are shown for those coated with a thermosetting resin having various properties of 8%, 8%, 9%, 10% and 12%.

As a test method, the capacitor was held in a constant temperature bath at 85 ° C., an alternating voltage of 1.3 times the rated voltage was continuously applied, and a DC voltage of 800 V was applied to a dump condenser having a capacity of twice the test capacitor. A voltage is applied, and the charging voltage of the dump converter is applied to the capacitor once for 15 seconds. Then, when the safety function of the capacitor is activated, the thermosetting resin coating the capacitor element has a crack (exterior crack) or other large external change until the fully opened state and the flowing current becomes 0 A. Judgment was made based on whether smoking or ignition occurred.

Further, the above capacitor was held in a constant temperature / humidity bath at 85 ° C. and 85% to perform a humidity resistance test, and the rate of change in capacitance before and after 500 hours was measured. Table 1 shows the results of the comprehensive judgments of the above-mentioned safety test and moisture resistance characteristic test.

[0020]

[Table 1]

As is clear from the results shown in Table 1, in the capacitor of the present invention, the thermosetting resin for coating the exterior has a glass transition point of 65 to 100 ° C. and an elongation of 3 at 25 ° C.
About 8% is kept in 85 ° C, 85% constant temperature / humidity tank and tested for humidity resistance, and the capacitance change rate before and after 500 hours is good within ± 5%, but it is safe. In the test, even if the safety function of the capacitor operates and gas is generated to increase the internal pressure, the thermosetting resin expands as shown in FIG. 4 (in FIG. 3, the capacitor element is coated with the thermosetting resin. The capacitor was used to show the state before the operation of the safety function), and the operation of the safety function was completed without scattering of exterior cracks, ensuring 100% safety.

A thermosetting resin having a glass transition point of 60 ° C. or 105 ° C. and an elongation of 2% at 25 ° C. has a humidity resistance of 85 ° C. and 85% in a constant temperature and humidity chamber. Characteristic test was performed, and the rate of change in capacitance before and after 500 hours ± 5
% Is good, but in the safety test, when the safety function of the capacitor operates and gas is generated and the internal pressure rises, cracks (exterior cracks) occur in the thermosetting resin although there is no smoke ignition. Insulation cannot be secured and safety cannot be secured.

Further, if the thermosetting resin for coating the exterior has a glass transition point of 55 ° C. or less and an elongation of 9% or more at 25 ° C., the safety function of the capacitor operates in the safety test to generate gas. However, even if the internal pressure rises, the thermosetting resin expands as shown in FIG. 4, and the operation of the safety function is completed without scattering of exterior cracks, and 100% safety can be secured. In a humidity resistance test held in a 85% constant temperature and humidity chamber, the capacitance change rate after 500 hours is ±
It was 5% or more, which did not satisfy the regulation value, and therefore was rejected in the comprehensive judgment.

In addition to the above-mentioned embodiment, the electrode 2 formed on both surfaces of the dielectric film or the electrode 2 formed in a peninsular shape was also tested, but the same effect as described above was obtained. It was

[0025]

As described above, in the metallized film capacitor of the present invention, even if the safety function operates and gas is generated and the internal pressure rises, the exterior thermosetting resin expands correspondingly. Does not cause cracks (exterior cracks),
It is highly safe with no exposure of electrodes and the like, has a small rate of change in capacitance in a humidity resistance test, is small, inexpensive, and easy to manufacture, and is of great industrial and practical value.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a metallized film capacitor element according to the present invention.

FIG. 2 is a perspective view showing a state in which the safety function of the metallized film capacitor element according to the present invention is activated.

FIG. 3 is a side sectional view of the metallized film capacitor of the present invention.

FIG. 4 is a side sectional view showing a state where the safety function of the metallized film capacitor element according to the present invention is activated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric film 2 Electrode 3 Insulation groove 4 Insulation groove 5 Metallized film 6 Capacitor element 7 Electrode lead portion 8 Lead wire 9 Mechanical contact portion between electrode lead portion 7 and electrode 10 Thermosetting resin

Claims (1)

[Claims] 1. A dielectric film is provided with an insulating groove on one or both sides in an end portion in the width direction to vapor-deposit metal to form an electrode, and a plurality of electrodes are formed in the length direction of the dielectric film. A metallized film is formed by providing a plurality of insulating grooves in the lengthwise direction connected to the insulating groove so as to be formed in an island shape or a peninsular shape, and the metallized film is wound to form a capacitor element. The element has a glass transition point of 6
A metallized film capacitor coated with a thermosetting resin having a property of 5 to 100 ° C and an elongation of 3 to 8% at 25 ° C.