JP2008198924A - Metallizing film capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict a capacity drop of a metallizing film capacitor and improve reliability. <P>SOLUTION: After a pair of metallizing films, in which a metal deposition electrode is formed on dielectric film, are so wound that each metal deposition electrode is put opposite to each other through the dielectric film, the outer boundary side of the winding side face is covered with enveloping film made of any one of polyethylenenaphthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate so that flat topography is obtained by compressing the wound body perpendicularly from both sides to the center with respect to the winding axis. In the thus processed metallizing film capacitor, which is subjected to annealing at a thermal aging temperature of 140-170°C, the thermal shrinkage of the enveloping film at thermal aging temperature is larger than thermal shrinkage at thermal aging temperature of the dielectric film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a metallized film capacitor which is used in various electronic devices, electric devices, industrial devices, automobiles and the like, and is particularly suitable for smoothing, filtering, and snubber of an inverter circuit for driving a motor of a hybrid vehicle.

  In recent years, from the viewpoint of environmental protection, all electric devices are controlled by inverter circuits, and energy saving and high efficiency are being promoted. In particular, in the automobile industry, hybrid vehicles (hereinafter referred to as HEVs) that run on electric motors and engines have been introduced into the market, and the development of technologies relating to energy saving and high efficiency has been activated, which is friendly to the global environment.

  Since such a HEV electric motor has a high operating voltage range of several hundred volts, a metallized film capacitor having high withstand voltage and low loss electric characteristics as a capacitor used in connection with such an electric motor. In addition, the trend of adopting metalized film capacitors with a very long life is conspicuous due to the demand for maintenance-free in the market.

  And since this kind of metallized film capacitor is mounted on automobiles, high heat resistance and high voltage resistance are required, and various developments and proposals for high heat resistance and high voltage resistance have been made. Met.

  In particular, as a film capacitor having excellent heat resistance, polyethylene naphthalate, polyphenylene sulfide, and polyimide have been used for dielectric films.

  Further, in order to improve the volumetric efficiency with respect to the capacity, the wound capacitor element is subjected to pressure from both directions to form an oblong flat shape.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2004-285298 A

  However, in the conventional metallized film capacitor described above, the heat aging treatment is performed after the capacitor element is formed into a flat shape, so that when the treatment for reducing the so-called loosening of the capacitor element is performed, the conventional heat aging treatment temperature is used. In a certain heat treatment at about 120 ° C., the heat resistance of the dielectric film is high, so that loose winding remains, resulting in a decrease in capacity and a short circuit breakdown at a low voltage.

  Accordingly, an object of the present invention is to reduce loosening of the capacitor element after heat aging treatment of the capacitor element having a flat shape using a high heat-resistant dielectric film.

  In order to achieve the above object, the present invention provides a flattened film obtained by winding a metallized film having a metal-deposited electrode on a dielectric film made of any one of polyethylene terephthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate. Heat shrinkage of the exterior film at a heat aging temperature of 140 to 170 ° C. with respect to the exterior film made of any one of polyethylene naphthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate covering the outer periphery of the capacitor element having a shape. The rate is greater than the thermal shrinkage at the heat aging temperature of the dielectric film.

  As described above, the metallized film capacitor according to the present invention has a heat shrinkage rate at the heat aging temperature of the outer film of the capacitor element, which is larger than the heat shrinkage rate at the heat aging temperature of the dielectric film. As a result, the outer film shrinks and tightens by heat, and the winding of the capacitor element can be further reduced.

(Embodiment)
FIG. 1 is an exploded perspective view showing the configuration of a metallized film capacitor according to an embodiment of the present invention (in order to make the configuration easy to understand, omitting a molding resin described later), and FIG. FIG. 3 is a plan view showing a configuration of a capacitor. In FIGS. 1 and 2, reference numeral 1 denotes a capacitor element. The capacitor element 1 has a winding axis with respect to a metallized film or the like wound later. After forming into a flat shape with an oval cross section by compressing so as to be sandwiched from a direction perpendicular to the two, a pair of metallicon electrodes 1a are formed on both end faces by metal spraying.

  Reference numeral 2 denotes a pair of bus bars, 2a denotes an external connection terminal provided at one end of the bus bar 2, and the bus bar 2 has a plurality of capacitor elements 1 (five in the present embodiment) arranged. In this state, a pair of metallicon electrodes 1a formed on both end faces of the capacitor element 1 are soldered via soldering portions 2b as shown in FIG. 1, whereby a plurality of capacitor elements 1 are connected in parallel. It is what you are doing.

  Reference numeral 4 denotes a resin case in which a plurality of capacitor elements 1 connected in parallel by the bus bar 2 are housed. In the present embodiment, PPS (polyphenylene sulfide) is used as a material of the case 4. Yes.

  In FIG. 2, reference numeral 5 denotes a mold resin cast in the case 4, and the mold resin 5 is in a state where the external connection terminal portion 2 a provided at one end of the bus bar 2 is exposed from the case 4. A plurality of capacitor elements 1 and bus bars 2 are covered, and in this embodiment, an epoxy resin is used.

  Here, the production of the capacitor element 1 will be described in more detail.

  3 is a cross-sectional view of the capacitor element 1 with the metallicon electrode 1a removed, and FIG. 4 is a perspective view of the capacitor element 1 further compressed into a flat shape.

  In FIG. 3, first, a pair of metallized films in which a metal deposition electrode such as aluminum is formed on a dielectric film made of any one of polyethylene naphthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate (not shown) are deposited on the metal. The metallized film wound body 6 is formed by winding the electrodes so as to face each other through the dielectric film.

  Next, the outer periphery of the winding side surface of the metallized film winding body 6 is covered with at least one outer covering film made of any one of polyethylene naphthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate. Layer 7 is formed. At this time, the heat shrinkage rate at the heat aging temperature described later of the exterior film used for the exterior film layer 7 is larger than the heat shrinkage rate at the same heat aging temperature of the dielectric film constituting the metallized film winding body 6. Suppose that

  Then, by compressing the metallized film winding body 6 and the exterior film layer 7 so as to be sandwiched from the direction perpendicular to the winding axis, the capacitor element 1 in a state where the metallicon electrode 1a is removed as shown in FIG. Is made.

  Further, the heat aging treatment is performed at a heat aging temperature of 140 to 170 ° C., which is about 10 ° C. to 40 ° C. higher than the use temperature and is such that the film used is not subject to extreme heat damage. This removes moisture in the metallized film wound body 6 by applying a certain thermal load to the metal vapor deposition electrode in the metallized film, increases the withstand voltage, and when the metallized film is wound. The purpose is to eliminate so-called loosening at the time of compression into a flat shape. At this time, if the temperature is not more than 10 ° C above the operating temperature, the effect of eliminating the loosening is thin. It will cause extreme heat damage.

  After the heat aging treatment, the metallized electrode 1a is formed by spraying a metal such as zinc or tin from both end surfaces in the winding axis direction of the metallized film winding body 6 to form the capacitor element 1. .

  Conventionally, the above-mentioned polyethylene naphthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate are high heat-resistant dielectric films that do not cause thermal shrinkage even in the vicinity of 140 to 170 ° C., which is lower than about 120 ° C. In the heat aging treatment performed in step 1, the loosened winding of the metallized film wound body 6 remains.

  On the other hand, according to the metallized film capacitor configured as described above, the heat shrinkage rate at the heat aging temperature of the exterior film is larger than the heat shrinkage rate at the heat aging temperature of the dielectric film, so that the heat treatment is performed at 140 to 170 ° C. In the heat aging treatment, the metallized film winding body 6 and the exterior film layer 7 are tightly wound, and the capacity can be prevented from decreasing.

  In addition, conventionally, the thermal shrinkage of polyethylene naphthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate caused a large thermal shrinkage near 200 ° C., but the crystallinity was lowered during film formation. Then, by causing thermal shrinkage even at 140 to 170 ° C., the thermal shrinkage rate at the thermal aging temperature of the exterior film is made larger than the thermal shrinkage rate at the thermal aging temperature of the dielectric film.

  Further, by making the thermal shrinkage rate in the longitudinal direction of the exterior film used for the exterior film layer 7 larger than the thermal shrinkage rate in the width direction, the tightening becomes more effective and the reduction in capacity can be suppressed. .

  The type of film used for the dielectric film and the type of film used for the exterior film may be the same or different.

  In the first place, when it is used for automobiles, it is often used in a high temperature atmosphere, and in particular, the operating temperature reaches 130 ° C. to 150 ° C. by being arranged on the drive axle or by simplifying the cooling mechanism. Therefore, when the capacitor element 1 is housed together with the mold resin 5 in the case 4 as in the present embodiment, the improvement in reliability becomes more remarkable.

  The metallized film capacitor according to the present invention can increase the heat resistance of the capacitor element and improve the reliability, and is therefore useful for automobiles that require particularly high reliability.

The disassembled perspective view which showed the structure of the case mold type capacitor by one embodiment of this invention Sectional view showing the configuration of the same case mold type capacitor Sectional drawing of the capacitor | condenser element by one embodiment of this invention The perspective view of the metallized film winding body by one embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 1a Metallicon electrode 2 Bus bar 2a Terminal part 2b for external connection Soldering part 4 Case 5 Mold resin 6 Metallized film winding body 7 Exterior film layer

Claims (2)

A pair of metallized films in which a metal vapor deposition electrode is formed on a dielectric film made of any one of polyethylene naphthalate, polyphenylene sulfide, polyimide, and polyethylene terephthalate so that the metal vapor deposition electrodes face each other through the dielectric film. After winding, the outer periphery of this winding side is covered with an exterior film made of any one of polyethylene naphthalate, polyphenylene sulfide, polyimide, polyethylene terephthalate, and compressed so that it is sandwiched from the direction perpendicular to the winding axis. In a metallized film capacitor constituted by a capacitor element in which a metallicon electrode is formed by metal spraying on both end surfaces in the winding axis direction after performing a heat treatment at a heat aging temperature of 140 to 170 ° C. The outer the heat aging large metalized film capacitors than the heat shrinkage at a temperature of the thermal shrinkage ratio in the heat aging temperature is the dielectric film of the film. The metallized film capacitor according to claim 1, wherein the heat shrinkage rate in the longitudinal direction of the exterior film is larger than the heat shrinkage rate in the width direction.

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