JPH0121544Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an improvement of a dry metallized film capacitor, and provides an extremely safe dry metallized film capacitor. Conventionally, dry metallized film capacitors are made of a plastic dielectric film such as polypropylene film, polyethylene terephthalate film, polycarbonate film, or polystyrene film, and a metal such as aluminum or zinc is provided at the widthwise end of the dielectric film with an insulating margin. hand
A capacitor element is formed by stacking vacuum-deposited metallized films to a thickness of 0.02 to 0.03 μm so that the insulation margins are on the opposite side, and spraying metals such as solder and zinc on both end faces of the capacitor element. Then, lead wires or terminals were connected to the electrode lead-out portions obtained by forming the contact layer, and the capacitor was housed in a case and then sealed to form a dry metallized film capacitor. In a dry metallized film capacitor constructed in this manner, the film may partially break during a current test due to insulation defects contained within the dielectric film or insulation defects formed during metal deposition. However, since the electrode is an extremely thin vacuum-deposited film as mentioned above, the energy from this partial breakdown can scatter the deposited metal layer, and generally the insulation is restored and the capacitor can be used again. becomes. However, although the deterioration of the metallized film is negligible at the initial stage, the destruction progresses little by little, with some destroyed parts as the core, and there is a danger that it will eventually catch fire and smoke. In order to improve such defects, as shown in FIG. 1 and known in Japanese Patent Application Laid-Open No. 57-114219, an insulating margin portion 2 is provided at the end in the width direction on at least one side of the dielectric film to form an electrode. A metallized film 1 is wound around a metallized film 1 provided with structural grooves 4 so as to separate the electrode 3 into a plurality of islands in the length direction of the dielectric film. A metallized film capacitor is shown. However, in order to obtain a self-safety function, it is necessary to make the interval P between the insulating grooves 4 as small as possible, which has the disadvantage that the capacitance loss due to the insulating grooves 4 becomes large. Furthermore, when the capacitor capacity is large, self-heating also increases, so there is a risk of rapid breakdown due to thermal causes. Furthermore, in order to improve these, as shown in Japanese Patent Laid-Open No. 57-20421 and Japanese Patent Laid-Open No. 57-136312, a thin part of the deposited film is provided at the end of the metal irradiation, and the deposited film is scattered at this part. However, in all of these methods, auxiliary masking tape is used during vapor deposition to partially thin the vapor deposited film, which requires complicated equipment and is difficult to manufacture. When such a vapor-deposited metal is stored for a long period of time, depending on the conditions, the high film resistance portion tends to change over time, resulting in a lack of quality stability. The present invention improves these drawbacks and provides a dry metallized film capacitor which has a simple structure, has a self-protection function, is highly stable in quality, and has good productivity. The present invention will be described below with reference to embodiments shown in FIGS. 2 to 5. An insulating margin portion 2 is provided at one end in the width direction of a dielectric film, that is, a polyethylene terephthalate film and a polypropylene film, and an electrode 3 is formed.
A metallized polyethylene terephthalate film 1a and a metallized polypropylene film 1b are formed, and an insulating groove 4a is provided in the length direction of the film to connect the electrode 3a of the metallized polyethylene terephthalate film 1a. A capacitor element 6 is formed by stacking and winding the film 1a and the metallized polypropylene film 1b so that the insulating margin part 2 is on the opposite side, and a contact layer is formed by metal spraying, and a terminal is attached to the obtained electrode lead part 5. Alternatively, after connecting with the lead wires, the metallized film capacitor is constructed by sheathing with resin. In particular, if heat treatment is performed in the atmosphere under appropriate conditions after forming the contact layer, as shown in Fig. 3. Insulating margin portion 2 end portion 2' of metallized polypropylene film 1b
A weak point 3 in the vicinity of which vapor-deposited metal scattering of the metallized polyethylene terephthalate film 1a is likely to occur.
a' is formed, and as shown in FIG. 4, when the dielectric film is partially destroyed, the weak point 3a' scatters and separates the electrode 3a at that part, which significantly stabilizes the self-safety function and further improves the By thermal shrinkage of the metallized film, we were able to obtain a highly productive dry-type metallized film capacitor with little capacity loss. Next, the above embodiment will be explained in more detail. Aluminum vapor deposited film resistance value 6Ω/hole, thickness 6μm
Metallized polyethylene terephthalate film 1
Insulating grooves 4a are provided at intervals P=20 mm in a, and this and a metallized polypropylene film 1b with an aluminum vapor-deposited film resistance of 6 Ω/hole and a thickness of 5 μm are stacked and wound so that the insulating margin portion 2 is on the opposite side. A capacitor element with a capacitance of 20 μF was formed, a contact layer was formed by metal spraying, and after heat treatment at various temperatures in the atmosphere, terminals were connected and resin exterior was applied. After measuring the initial characteristics of this sample, the capacitor was forcibly destroyed and a self-safety function test was conducted. The results are shown in the table below.

[Table] As is clear from this result, the heat treatment temperature was
A good self-protection function can be obtained by setting the temperature to .degree. C. or above, but on the other hand, if the treatment temperature is increased, tan .delta. as an initial characteristic becomes high, which is not preferable. Therefore, in order to obtain good initial properties and self-protection function, it is preferable to heat treat at 100 to 120°C. In the above method, an insulating margin is provided at the end of the polyethylene terephthalate film in the width direction to form an electrode, and a plurality of insulating grooves are provided in the length direction of the polyethylene terephthalate film to completely form the electrode into multiple pieces. The experiment was carried out on the divided metallized film. In addition, as shown in FIG. 5, the metal sprayed side vapor deposited electrode of the metallized polyethylene terephthalate film 1a was partially left narrow in the length direction, and an insulating groove 4a was formed. Even in the case where multiple evaporation electrodes are connected to each other with a narrow evaporation electrode left behind, the dielectric material is not generated when a part of the evaporation electrode is partially broken, and the evaporation metal existing in a narrow width is scattered and the evaporation electrode becomes wider. The result is the same as when the metallized polypropylene film 1b is completely divided into a plurality of pieces, and then the vapor-deposited metal of the metallized polyethylene terephthalate film 1a is scattered near the end portion 2' of the insulation margin 2 of the metallized polypropylene film 1b, resulting in a similar result. Obtained. Furthermore, the self-safety function of the capacitor obtained by winding the metallized polyethylene terephthalate film 1a provided with the insulating grooves 4a as described above is as shown in FIG. Since this is obtained by scattering in the longitudinal direction of the weak point 3a' of the vapor deposition electrode 3a near the end 2', the metallized polypropylene film 1 facing the metal sprayed side end of the metallized film 1
Distance L between b and end 2' of insulating margin part 2
If L is 0.1 mm or more, the above effects can be obtained, but if this distance L is too long, the contact between the vapor deposition electrode and the sprayed metal will deteriorate, which will affect reliability, which is not preferable. Therefore, the above distance L is
0.1 to 2.0 mm is preferred. Note that the above heat treatment was carried out in the atmosphere, but
Even if this is carried out in a vacuum, the thermal behavior remains unchanged and the same effect is obtained. As mentioned above, the dry-type metallized film capacitor of the present invention is dry-type, has an extremely safe self-protection function, provides a highly reliable and highly productive capacitor, and has extremely high practical value. It is.

[Brief explanation of drawings]

Figure 1 is an exploded perspective view of the main parts of a conventional dry-type metallized film capacitor, Figure 2 is an explanatory diagram of the main part of the electrode arrangement of an embodiment of the dry-type metallized film capacitor of the present invention, and Figure 3 is an explanatory diagram of the main part of the electrode arrangement of the dry-type metallized film capacitor of the present invention. Figure 4A is an explanatory diagram of the main part of the electrode arrangement of a dry-type metallized film capacitor constructed by heat treatment. FIG. 5 is an exploded perspective view of a main part of another embodiment of the dry metallized film capacitor of the present invention. 1a...Metalized polyethylene terephthalate film, 1b...Metalized polypropylene film, 2...Insulating margin portion, 3, 3a, 3b...
Electrode, 4, 4a... Insulating groove, 5... Electrode extraction part,
6...Capacitor element.

Claims (1)

[Claims for Utility Model Registration] (1) A metallized film in which an electrode is formed by providing an insulating margin at the end of the dielectric film in the width direction is rolled in a stacked manner so that the insulating margin is on the opposite side. In a dry-type metallized film capacitor that is made up of an exterior capacitor element with electrode extensions formed on both end faces, the electrodes are vapor-deposited on a polyethylene terephthalate film and metallized with multiple insulating grooves in the length direction of the polyethylene terephthalate film. A capacitor element in which a polyethylene terephthalate film and a metallized polypropylene film having electrodes deposited on the polypropylene film are layered and wound, electrode extensions are formed on both end faces, and heat-treated in air or vacuum, and the electrode extensions are A dry metallized film capacitor comprising: a terminal or lead wire connected to the capacitor element; and a resin sheathing the capacitor element. (2) The dry metallized film capacitor according to claim 1, wherein the insulating groove is configured to separate the electrode into a plurality of islands in the length direction of the polyethylene terephthalate film. . (3) The above-mentioned insulating groove is configured to separate the electrode into a plurality of pieces in the length direction of the polyethylene terephthalate film, leaving a part of the electrode on the metal spraying side narrow. 1
Dry metallized film capacitors as described in . (4) The distance L between the metal sprayed end of the metallized polyethylene terephthalate film and the insulation margin end of the opposing metallized polypropylene film is within the range of 0.1 to 2.0 mm. A dry metallized film capacitor according to claim 2 or 3 of the utility model registration claim.