JP2013172045A - Film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heating even if size of a capacitor element increases and a current flowing a leading electrode increases so that currents flowing in the vicinity of connection concentrate, with no complicated connection between respective leading electrodes and an external terminal, relating to a film capacitor which includes two capacitor elements in which a film is used as dielectrics and wound, provided with a metallicon electrode at both ends thereof for electrical parallel connection, a tubular bottomed case having an opening on an upper end surface thereof for housing the capacitor elements stacked in winding axis direction, a sealing body for sealing the opening of the tubular case, an external terminal penetrating the sealing body, and a leading foil electrode to which the external terminal and the metallicon electrode are connected.SOLUTION: A leading electrode connected to a metallicon electrode on an external terminal side is provided by integrally extending from a leading electrode of a different capacitor element having the same polarity.

Description

  The present invention relates to a film capacitor.

A capacitor element of a film capacitor uses a film as a dielectric and is formed by depositing a thin film metal electrode on the film, or by winding or laminating a metal foil through this film, and zinc is formed on both end faces. Further, a metal such as copper or aluminum is adhered by metallicon to form an element external electrode (hereinafter referred to as a metallicon electrode).
In such capacitors, self-healing of the capacitor element can be achieved by increasing the deposited film thickness in order to improve the conductivity value of the deposited film as an improvement to reduce the equivalent series resistance and to reduce the loss and heat generation. Performance decreases, and the pressure resistance of the capacitor element decreases. For this reason, Patent Document 1 discloses a method in which one capacitor element is divided and at least two capacitor elements are connected in parallel as a method for shortening the distance to the metallicon electrode of the capacitor element without increasing the deposition film thickness. Is described.
Further, in Patent Document 2, in order to reduce heat generation during operation of a film capacitor having a plurality of capacitor elements, a foil-like metal plate is connected as a lead electrode to a metallicon electrode, and each capacitor element is pulled out. It describes that it is easy to dissipate heat by transferring internal heat to the foil-shaped metal plate.

Japanese Utility Model Publication No. 7-29829 JP 2008-270329 A

  By the way, the lead-out electrodes drawn out from the plurality of capacitor elements are connected to the external terminals of the capacitors, but the connection between the individual lead-out electrodes and the external terminals of the capacitors tends to be complicated. Further, when the capacitor element is enlarged and the current flowing through the extraction electrode is increased, the current flowing near the connection is likely to be concentrated and generate heat.

  In the present invention, the connection between the extraction electrode and the external terminal to be collected is not complicated, the capacity of the capacitor element increases, the current flowing through the extraction electrode increases, and even if the current flowing near the connection is concentrated, the degree of heat generation The purpose is to suppress.

In order to solve the above problems, the present invention provides the following film capacitor.
(1) Two capacitor elements wound using a dielectric film and provided with metallicon electrodes at both ends thereof, and a bottomed cylinder having an opening on the upper end surface for accommodating the capacitor elements stacked in the winding axis direction A cylindrical case, a sealing body for sealing the opening of the cylindrical case, an external terminal penetrating the sealing body, and connecting the external terminal and the metallicon electrode or electrically connecting the two capacitor elements A film capacitor having a foil-like lead electrode connected in parallel with the lead electrode, and the lead electrode connected to the metallicon electrode on the external terminal side is integrated with the lead electrode of another capacitor element having the same polarity as the film capacitor. (2) The lead-out electrode connected to the metallicon electrode on the external terminal side is another front of the same polarity as that of the film capacitor. The film capacitor according to (1), which is integrally extended on both sides of the lead electrode of the capacitor element.

  According to the present invention, the lead electrode connected to the metallicon electrode on the external terminal side is provided so as to be integrally extended from the lead electrode of another capacitor element having the same polarity as the lead electrode. Even if the connection with the external terminal is not complicated, the capacitor element is enlarged, the current flowing through the extraction electrode is increased, and the current flowing near the connection is concentrated, the degree of heat generation can be suppressed.

2 shows two capacitor elements of the present invention and lead electrodes connected to the capacitor elements. 2 shows two capacitor elements of the present invention and another lead electrode connected thereto. The example of the schematic sectional drawing of the capacitor | condenser of this invention is shown.

  The metallicon electrode described in the present invention is an element external electrode connected to the end of an electrode of a capacitor element, and a metal such as zinc, copper, or aluminum deposited by metallicon (spraying) can be used.

  The capacitor element described in the present invention uses a film as a dielectric and is wound together with an electrode. A thin film metal electrode is provided by vapor deposition on a film, or a method of winding a metal foil through the film. included. On both end faces, element external electrodes (metallicon electrodes) in which metal is adhered by metallicon are formed. As the film, polyethylene terephthalate, polypropylene or the like can be used, and as the metal of the metal foil or thin film metal, aluminum, copper, zinc or an alloy thereof can be used. The cross-sectional shape is circular, and when it is crushed, it becomes a flat shape.

The case of the present invention is a bottomed cylindrical container having an opening on the upper end surface and generally usable for a film capacitor, and can be formed of plastic or metal. In the case of plastic, for example, a resin such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, or polyphenylene sulfide can be used. As long as it is a metal, for example, aluminum, magnesium, iron, stainless steel, copper, or an alloy thereof can be used.
A capacitor element is provided in the case, most of which is filled with an insulating resin or the like. Insulating resin is an insulating material generally used for filling film capacitors, and is made by mixing a filler or the like with a resin such as epoxy resin or urethane resin. As the filler, hydroxides such as silicon, titanium, aluminum, calcium, zirconium, and magnesium, oxides, carbides, nitrides, and composites thereof can be used. If necessary, a flame retardant and an antioxidant may be added.

The sealing body of the present invention is an insulator that seals the opening of the case, and is provided with an external terminal described below.
When the inside of the case is filled with resin, it is not always necessary to provide a sealing body at the opening of the case, but the external terminal can be stably provided and the insulation, moisture resistance, and durability are improved. To do.

  The external terminal of the present invention is an electrode terminal penetrating from the outer surface to the inner surface of the sealing body, and is connected to the outside of the capacitor, and the inside of the capacitor is connected to a lead electrode described below. The shape of the external terminal is a cylindrical or polygonal molded body, and is not particularly limited, but the portion protruding from the outer surface of the sealing body is the inner side or the outer side so that it can be easily connected to the outside of the capacitor. Threaded on the outside. The material is made of a metal or alloy such as copper, aluminum, iron, nickel, stainless steel, phosphor bronze, or brass, and tin, solder, or the like may be plated on the surface.

The lead electrode described in the present invention is an electrode for connecting to a metallicon electrode and leading to the outside, and a metal foil such as a metal such as copper, aluminum, iron, nickel, stainless steel, phosphor bronze, brass, or an alloy can be used. Moreover, tin, solder, etc. may be plated on the surface. Tin-plated copper is preferred. The thickness and shape are designed in consideration of allowable current, ESL (equivalent series inductance), strength, stress reduction, and the like required by the product.
Each connection between the lead electrode and the external terminal is not particularly limited, such as spot welding, caulking, soldering, etc., but for the purpose of stable connection against a large current, soldering is possible because the connection area can be widened. preferable.
Further, the lead electrode connected to the metallicon electrode on the external terminal side is provided so as to extend integrally from the lead electrode of another capacitor element having the same polarity as the lead electrode.
By the way, if the lead electrode is provided separately for each capacitor element, it will be connected to the external terminal separately. When connecting by soldering, it is necessary to prepare two kinds of solder materials having different melting temperatures, The work is also complicated. Further, when trying to connect together with external terminals by caulking, the contact area tends to be small and it is difficult to increase the flowing current.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows two capacitor elements of the present invention and lead electrodes connected to the capacitor elements.
The two capacitor elements 1 are each wound using a metallized film to form a cylindrical shape, provided with metallicon electrodes 2a and 2b on both end faces, and stacked in the winding axis direction. In order to connect the two capacitor elements 1 in parallel and connect to the outside, a pair of lead electrodes connecting the pair of external terminals 3a, 3b provided on the upper end surface side of the capacitor element 1 and the respective metallicon electrodes 2a, 2b 4a and 4b are provided. As the lead electrodes 4a and 4b, one metal foil cut out and bent is used.
In FIG. 1, the lead-out electrode 4 a on the back side uses a metal foil processed into a U-shape, the U-shaped base metal metal electrode 2 a facing one external terminal 3 a and the U-shaped tip between the capacitor elements 1. And connect respectively.
Further, in FIG. 1, the leading electrode 4 b on the front side uses a metal foil processed into a strip shape, the lower end of the strip is the bottom side of the capacitor element 1 on the lower side and the upper end of the strip is the other end. The external terminal 3b and the metallicon electrode 2b on the external terminal 3b side are connected to each other by an extending portion 5 that extends integrally from the lead electrode 4b. Further, the width of the portion between the extended portion 5 of the extraction electrode 4b and the external terminal 3b is increased by adding the width of the extended portion 5 so as not to reduce the current density.

  Also, if the metallicon electrode 2b on the surface on the external terminal 3b side is integrally extended on both sides of the lead electrode 4b, the connection area with the metallicon electrode 2b is dispersed rather than extending only from one side. Since the heating temperature and time at the time of connection can be reduced, it is possible to suppress thermal deterioration between the capacitor element 1 main body portion and the metallicon electrode 2b in the peripheral portion. Further, since the width or thickness of the extending portion 5 can be reduced without reducing the current density, the portion is easily deformed and is easily relieved against the connection stress between the extraction electrode 4b and the metallicon electrode 2b.

FIG. 2 shows two capacitor elements of the present invention and another lead electrode connected thereto.
The structure is the same as that shown in FIG. 1 except that the shape of the leading electrode 4b on the near side is different.
In FIG. 1, the extraction electrode 4 b is bent along the upper end surface of the upper capacitor element 1, whereas in FIG. 2, the extraction electrode 4 b is bent away from the upper end surface of the upper capacitor element 1. However, it is different in that the extended portion 5 is bent so as to approach the upper end surface of the upper capacitor element 1. Due to this floating, it is possible to make it difficult to transmit the heat generation of the extraction electrode 4b to the upper capacitor element 1 at the portion where the current of the upper capacitor element 1 and the current of the lower capacitor element 1 collide with each other.

FIG. 3 shows an example of a schematic cross-sectional view of the capacitor of the present invention. Two capacitor elements 1 wired in the same manner as in FIG. 1 are housed in a case 6 having an opening with an open upper end surface, and the opening of the case 6 is sealed with a sealing body 7. The sealing body 7 is provided with a pair of external terminals 3 with screws passing through the outer surface and the inner surface, and a fastener 8 is provided so that the external terminals 3 do not come out of the sealing body 7. An example of a film capacitor filled with a filling resin 9 is shown.
The filling resin 9 is injected into the case 6 from the through hole 10 provided in the sealing body 7 and protrudes from the through hole 10 to the outer surface so that the fastener 8 provided on the external terminal 3 is buried. The protruding resin is damped by a damming function such as a dam-shaped circular body or a damming groove provided on the outer surface of the sealing body 7. The damming function is preferably integrated with the sealing body 7, but may be a separate part. For example, when the adhesive tape is circulated in a dam shape, or when the heat shrinkable tube is provided on the outer periphery of the side surface of the case 6, the protruding resin may be damped by protruding to the external terminal 3 side.

First, aluminum is vapor-deposited at a thickness of 200 angstroms on one side, and two 7 μm-thick belt-like polyester films on which metal electrodes are formed are overlapped and wound to form a columnar body with circular end faces. Two capacitor elements having a diameter of 10 cm are prepared, each having a metallicon electrode formed of zinc and tin metallicon on the surface thereof.
In addition, the lead electrode is processed into a strip shape in which a copper foil having a thickness of 0.4 mm is processed into a U-shape, and an extension part integrally extending from the lead electrode is added to the side connected to the external terminal. Prepare the product and connect the external terminals with solder.
Next, this set of capacitor elements was overlapped in the winding axis direction, and the extraction electrode was bent so as to match the capacitor element.
Next, the U-shaped lead electrode was connected by soldering to the metallicon electrode with the U-shaped tip facing each other between the capacitor elements. The striped lead electrode has a metallicon electrode on the bottom side of the capacitor element with the lower end of the strip, the other external terminal on the upper end of the strip, and a metallicon electrode on the external terminal side. Each of the extended portions integrally extending from the extraction electrode was connected by soldering.
Next, the capacitor element in which this wiring was completed was housed in a polyphenylene sulfide case and sealed with a sealing body.
Next, a filler of an epoxy resin composition was injected from a through hole provided in the sealing body to fill the inside of the case.

  DESCRIPTION OF SYMBOLS 1 ... Capacitor element 2, 2a, 2b ... Metallicon electrode, 3 ... External terminal, 4, 4a, 4b ... Lead-out electrode, 5 ... Extension part, 6 ... Case, 7 ... Sealing body, 8 ... Fastener, 9 ... Filling resin, 10 ... through hole

Claims (2)

  Two capacitor elements that are wound using a dielectric film and provided with metallicon electrodes at both ends, and a bottomed cylindrical case with an opening on the upper end surface that accommodates the capacitor elements stacked in the winding axis direction A sealing body for sealing the opening of the cylindrical case, an external terminal penetrating the sealing body, and connecting the external terminal and the metallicon electrode, or electrically connecting the two capacitor elements in parallel. A film capacitor having a foil-shaped lead electrode to be connected, wherein the lead electrode connected to the metallicon electrode on the external terminal side is integrally extended from the lead electrode of another capacitor element having the same polarity as the film capacitor. A film capacitor is provided.   The film capacitor according to claim 1, wherein the lead electrode connected to the metallicon electrode on the external terminal side is provided integrally extending on both sides of the lead electrode of another capacitor element having the same polarity as the lead electrode.

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