JPS63137407A - Metallized film capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a metallized film capacitor constructed by winding a metalized film in which metal electrodes are formed on the surface of a dielectric film by vapor deposition or the like. be.

Prior Art Conventionally, this type of metallized film capacitor is shown in Fig. 6a.
, b, a metal electrode 22 is formed on one or both sides of a dielectric film 21 such as a polypropylene film, a polyester film, or a polycarbonate film in the width direction of the dielectric film 21 by vapor deposition, sputtering, or the like. Insulating groove part (usually called margin part, hereinafter referred to as margin part) 23
The metallized film 24 is obtained by providing and forming the metallized film 24.

When obtaining a capacitor using such a metallized film 24, two metallized films 24 are overlapped and wound, and Zn is coated on both end surfaces of the wound metallized film 240.
, Sn, Cu, Pb, or other metal material is thermally sprayed to form an electrode lead-out part, and a lead wire is connected to the electrode lead-out part by welding or the like to form a capacitor element. The sheets are stacked so that the margin portion 3 faces the reflective side, and the electrodes are drawn out to form a capacitor element in the same way as in the above-mentioned wound type capacitor.

Problems to be Solved by the Invention By the way, if such wound type and laminated type capacitors are analyzed and evaluated in detail from the viewpoint of productivity, capacitor characteristics, etc., each type has advantages and disadvantages. In particular, the major difference in characteristics is that multilayer capacitors have a structure in which multiple small capacitance capacitors are connected in parallel, so even if a part of the metallized film breaks down due to some abnormality during use, If only one capacitor element loses its function, other capacitor elements are hardly affected, resulting in only a slight reduction in capacitance. This means that it is a very safe capacitor with a safety function.

On the other hand, wound-type capacitors are currently mainstream because they can be easily manufactured using conventional general equipment, but if some abnormality occurs during use, the metallized film may When a part of the metallized film undergoes a destruction phenomenon, the capacitance change due to the destruction phenomenon is negligible at the initial stage because it only decreases in proportion to the reduced area of the electrode of the metallized film. Since the wound type capacitor is a single capacitor, the damage gradually progresses without stopping, with a part of the broken part serving as a core, and eventually leads to smoke and ignition. Therefore, in this wound type capacitor, sufficient safety cannot be ensured unless some kind of safety device is added.

The present invention is intended to solve these problems, and aims to develop a capacitor that combines the high productivity of a wound-type capacitor with the high safety of a multilayer capacitor. be.

Means for Solving the Problem In order to solve this problem, the present invention provides electrodes that are arranged in a plurality of rectangular shapes in the length direction of the metallized film, separately from the margin parts provided at the ends in the width direction. A capacitor element is constructed by using a metallized film provided with a margin part connected to the margin part so as to be separated into islands, and by overlapping and winding two such metallized films.

In the present invention, since the element itself can have a safety function, there is no need to add another safety device, and a resin molded exterior using a plastic case is possible. The feature of the present invention is that in the filling resin that protects the capacitor element, J
Elongation based on IS K-6301 is 10 inches or more and 300%
The following thermosetting resins are used.

Operation With this configuration, if a part of the metallized film breaks down due to some abnormality during use, the breaking current will be concentrated at the broken point from the power source through the electrode lead-out part and the contact part of the electrode. At this time, since the mechanical contact part between the electrode lead-out part and the electrode has a certain electrical contact resistance, when the breakdown current passes through the contact part, Joule heat is generated.
The electrode metal film near the contact area evaporates and scatters. If part of the electrode metal film in this contact part scatters and loses continuity, the density of the current flowing through the remaining conductive contact part increases, generating even more Joule heat, which causes the remaining conductivity to disappear. The scattering of the electrode metal film near the contact area progresses at an accelerating rate, and eventually the electrode containing the broken point is completely insulated from the capacitor body, and the current to the broken point is cut off, as seen in the conventional product. There is no progress of destruction, so no smoke or ignition occurs.

Regarding a capacitor having a structure in which the capacitor element of the present invention is filled and packaged with a thermosetting resin in an outer case,
As a result of further investigation, in order to fully demonstrate the safety function mentioned above, the capacitor element with the safety function should be made of thermosetting resin with an elongation of 10% to 300% at temperatures above 30°C. They discovered that all they had to do was fill it up. If dielectric breakdown occurs due to some abnormality during use of a film capacitor at the generally rated operating temperature, and the safety function of the element itself operates as described above, the temperature of the capacitor element and the surrounding exterior surrounding the element will be lower than the capacitor temperature. It was confirmed that the temperature rose to 30°C or higher due to self-heating of the element. Furthermore, when the safety function operates, gas is generated and internal pressure increases. Therefore, by filling the exterior case with a thermosetting resin that has a certain elongation at 30°C or higher, the resin expands against the gas from the capacitor that is generated when the safety function is activated, causing the exterior to crack and scatter. Safety functions can be operated frequently.

Embodiment FIG. 1 is a block diagram of a metallized film capacitor according to an embodiment of the present invention. In FIG. 2, 6 is a capacitor element, 7 is an electrode extension part, 8 is a lead wire, 10 is a plastic case, 11 is filled resin.

That is, in the present invention, as shown in FIG.
A metallized film 4' is used in which a margin portion 6 connected to the margin portion 3 is provided so as to separate the electrode 2 into a plurality of rectangular islands in the length direction of the metallized film 4, and such metallization A capacitor element is constructed by overlapping two films 4' and winding them. With this configuration, it can be manufactured in the same way as a wound type capacitor, and the electrode structure is the same as a laminated type, so even if a part of the electrode 2 breaks down, This can prevent accidents such as ignition and smoke, which often spread to the whole area.

With this configuration, if a part of the metallized film breaks down due to some abnormality during use, a breaking current will be concentrated at the broken point from the power source through the contact portion between the electrode lead-out portion 7 and the electrode 2. At this time, since the mechanical contact portion between the electrode lead-out portion 7 and the electrode 2 has a certain electrical contact resistance, when the breakdown current passes through the contact portion, Joule heat is generated and the As shown in Figure 3, the electrode metal film near the contact area evaporates and scatters. If part of the electrode metal film in this contact part scatters and loses continuity, the density of the current flowing through the remaining conductive contact part increases, generating even more Joule heat, which causes the remaining conductivity to be lost. The scattering of the electrode metal film near the contact area progresses at an accelerated rate, and eventually the electrode 2, including the broken point, is completely insulated from the capacitor body and the current to the broken point is cut off. As a result, there is no progression of force destruction, and therefore no smoke or ignition occurs.

In addition, the following table shows the JI of the capacitor element of the present invention at 30°C.
Each elongation based on SK-6301 is 3%.

The results of safety tests are shown for plastic cases filled with thermosetting resins of 6%, 8%, 10%, 20%, and 60%.

The test method was to hold the capacitor in a constant temperature bath at the maximum operating temperature and at room temperature, and continue to apply an AC voltage of 1.3 times the rated voltage to a dump capacitor with twice the capacity of the test capacitor. Apply the DC voltage that is the maximum, and then apply the charging voltage of the dump capacitor to the capacitor once for 15 seconds. Then, by the time the capacitor's safety function was activated and the capacitor was completely open and the flowing current reached OA, a judgment was made based on whether there were any cracks or other major external changes in the plastic case or filled resin, and whether smoke or ignition occurred. .

As is clear from the results in this table, in the capacitor of the present invention, if the elongation of the filled resin is 10% or more, the filled resin will expand even if the capacitor's safety function operates and generates gas and the internal pressure increases. In contrast, when the capacitor was less than 10%, the capacitor did not ignite or emit smoke, but the filling resin cracked and the insulation between the terminals and the sheath was not ensured. .

Therefore, the elongation at 30°C or higher used in the present invention is 10
% or more is a resin that can fully exhibit the performance of a capacitor with a safety function. by the way,
As shown in FIG. 4, the relationship between resin temperature and elongation is a curve that has a peak at the TG point (glass transition point) temperature.

So, the TG point is the same and the elongation is 50, 100, 200, 3
Using capacitors filled with resins of 00, 400 and 500%, a tensile test was conducted on the capacitor lead wires at the temperature of this TG point under the conditions specified in JISC-4908.

As a result, in the case of a capacitor using a resin whose elongation exceeded 300% at 10 temperature points, the resin stretched at the contact portion between the lead wire and the resin, creating a gap. In this case, it is not possible to maintain airtightness of the capacitor element, resulting in deterioration of characteristics. Therefore, it is necessary to set the upper limit of the elongation of the resin to 300%.

Effects of the Invention As described above, the metallized film capacitor of the present invention can fully exhibit its high safety function, and is also a capacitor that is inexpensive, easy to manufacture, resource-saving, and highly effective in industry.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a metallized film capacitor according to an embodiment of the present invention, Fig. 2 is a perspective view showing main parts of the metallized film capacitor according to the invention, and Fig. 3 is a safety function in operation of the capacitor. Fig. 4 is a characteristic diagram showing the relationship between resin temperature and elongation, and Fig. 5 (
a) and (b) are perspective views showing general metallized films. 1... Dielectric film, 2... Electrode,
3, 5...Margin part, 4'...Metalized film, 6...Capacitor element, 7...
...Electrode extraction part, 10...Plastic case, 11...Filled resin. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure 5 (Yuf

Claims (1)

[Claims] A metallized film is constructed by forming an electrode on one or both sides of a dielectric film, and providing a plurality of insulating grooves so that the electrode is separated into a plurality of islands in the length direction of the film. A capacitor element is constructed by winding a film of
A metallized film capacitor filled with a thermosetting resin having an elongation of K-6301 of 10% or more and 300% or less.