JP2009267089A - Film capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film capacitor having an excellent dielectric loss (tan δ) characteristic. <P>SOLUTION: In this film capacitor, a long-shaped first support body 11 formed with electrode layers 13a, 13b, 13c, 13d, 13e, 13f insulated each other and extending in a plurality of longitudinal directions, a dielectric film 17 not formed with the electrode layer, and a long-shaped second support body 14 formed with a plurality of electrode layers 16a, 16b, 16c, 16d insulated each other and extending in a longitudinal direction are one over the other wound, and extraction electrodes 18, 19 are formed on both the ends to connect a plurality of capacitor elements in series. In the film capacitor, the electrode layers 13a, 13c, 13d, 13f at both the ends in a width direction of the first support body 11 are connected to the extraction electrodes 18, 19, respectively, and also a thickness of the first support body 11 is thicker than that of the second support body 14, and besides is equal to or more than 6 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a film capacitor for high withstand voltage in which a plurality of capacitors are connected in series.

  In film capacitors, so-called series capacitors having a circuit configuration in which a plurality of capacitor elements are connected in series inside a capacitor element are widely used in order to improve withstand voltage.

  As an example of a conventional series capacitor, a perspective view thereof is shown in FIG.

  In the series capacitor of FIG. 2, two strip electrodes 25a and 25b are vapor-deposited on the surface of the upper film 22 along the length direction of the film, and an insulating groove 24 is formed between the two strip electrodes 25a and 25b. In addition, the two strip electrodes 25a and 25b have both ends of the film in contact with the electrode lead portions 21a and 21b. On the surface of the lower layer film 23, a strip-like electrode 27 is deposited at the center along the length direction of the film, and insulating grooves 26, 26 are provided on both ends of the film. With this structure, the equivalent circuit of the metallized film capacitor is composed of a series circuit of two capacitor elements as shown in FIG.

For example, Patent Document 1 is known as prior art document information relating to the invention of the present application.
Japanese Unexamined Patent Publication No. 7-57955

  The series capacitor as described above is a capacitor that can withstand a higher voltage by connecting the capacitors in series. However, since the amount of current increases at the same time, the dielectric loss (or dielectric loss tangent, tan δ) is required to be small. It is done.

  In order to reduce the dielectric loss (tan δ), it is important that the contact between the strip electrodes 25a and 25b and the electrode lead portions 21a and 21b is sufficiently secured.

  Here, since the thickness of the strip electrodes 25a and 25b is very thin, the electrode lead portions 21a and 21b are in contact with part of both ends on the surface of the strip electrodes 25a and 25b in connection with the electrode lead portions 21a and 21b. It is necessary to form so as to.

  The electrode lead portions 21a and 21b are formed by metal spraying called metallicon. For the above reason, the width of the lower film 23 is increased to improve the contact between the strip electrodes 25a and 25b and the electrode lead portions 21a and 21b. It is made shorter than the width | variety 22 and the metal sprayed to the part of both ends on the surface of the strip | belt-shaped electrodes 25a and 25b adheres.

  Moreover, by making the width of the lower layer film 23 shorter than the width of the upper layer film 22, the contact surface of the electrode lead portions 21a and 21b can be increased by providing irregularities on the end face, thereby increasing the adhesive strength.

  For this reason, although not clearly shown in FIG. 2, both end sides of the upper layer film 22 protrude from both end sides of the adjacent lower layer film 23.

  Furthermore, since there is no electrode in the insulating groove portion 26, when the upper layer film 22 and the lower layer film 23 are wound, the difference in thickness is accumulated by the insulating groove portion 26 without this electrode, and both end sides of the upper layer film 22 are more It will be in a floating state.

  For this reason, the pressure at the time of metal spraying causes the both end sides of the upper film 22 to fall down and obstruct the contact between the strip electrodes 25a, 25b and the electrode lead portions 21a, 21b, resulting in a dielectric loss (tan δ) of the series capacitor. There was a problem that the characteristics increased and the characteristics deteriorated.

  Accordingly, an object of the present invention is to provide a film capacitor that hardly causes an increase in dielectric loss (tan δ) and has improved characteristics.

  In order to achieve this object, the film capacitor of the present invention includes a long first support body on which a plurality of longitudinally extending electrode layers that are insulated from each other are formed, and a dielectric film that does not form an electrode layer And a long second support body formed with a plurality of longitudinally extending electrode layers that are insulated from each other, and wound together, forming take-out electrodes on both end faces thereof to form a plurality of capacitor elements. A film capacitor connected in series, wherein the electrode layers on both ends in the width direction of the electrode layer on the first support are connected to the extraction electrode, and the first 1 is a film capacitor characterized in that the thickness of the support is larger than the thickness of the second support and is 6 μm or more.

  The thickness of the first support that forms the electrode layer whose both ends in the width direction are connected to the extraction electrode is thicker than that of the other second support and is 6 μm or more, thereby increasing the shape of the film capacitor. Without lowering, the falling of the support during metal spraying is reduced. As a result, the connection between the electrode layer and the extraction electrode is secured, and the increase in dielectric loss (tan δ) is suppressed, and the characteristics are improved. A film capacitor can be obtained.

  Hereinafter, the film capacitor of the present invention will be described with reference to one embodiment and the drawings.

(Embodiment)
FIG. 1 is a cross-sectional view of the film capacitor of the present embodiment.

  In FIG. 1, strip-like electrode layers 13 a, 13 b, 13 c, 13 d, 13 e, and 13 f that are insulated from each other by a non-deposition portion 12 that does not have an electrode layer are formed on both surfaces of a first support 11 by metal deposition such as aluminum. It is formed continuously in the direction.

  In addition, strip-like electrode layers 16a, 16b, 16c, and 16d that are insulated from each other by the non-deposition portion 15 having no electrode layer are formed on both surfaces of the other second support 14.

  And between the 1st support body 11 and the 2nd support body 14, the dielectric film 17 in which the electrode layer is not formed is pinched | interposed, These 1st support body 11, the dielectric film 17, and 2nd After the support 14 is overlapped and wound, extraction electrodes 18 and 19 (corresponding to electrode extraction portions in the conventional example) are formed on both end surfaces by a method such as metal spraying such as metallicon.

  As the dielectric film 17, an organic film such as a polypropylene film (hereinafter referred to as PP film) or a polyethylene terephthalate film (hereinafter referred to as PET film) is used.

  The supports 11 and 14 are base materials for holding the electrode layers 13 and 16 and may be made of an insulating organic film, but the same PP film or PET film as the dielectric film is used. May be.

  With such a configuration, the electrode layer 13d and the electrode layer 16a facing each other with the dielectric film 17 interposed therebetween, the electrode layer 16a and the electrode layer 13e, the electrode layer 13e and the electrode layer 16b, and the electrode layer 16b and the electrode layer 13f between Two series connected capacitor elements are formed.

  Further, in FIG. 1, since the dielectric film 17 is also disposed below the second support 14 and wound, the entire four capacitor elements connected in series are connected in parallel as a whole. It becomes.

  The electrode layers 16a, 16b, 16c, and 16d are so-called intermediate electrodes, and are not connected to the extraction electrode 18 and the extraction electrode 19.

  Here, as shown in FIG. 1, the width of the second support 14 and the dielectric film 17 is shorter than that of the first support 11, and the electrode layer 13 a and the electrode on the first support 11. The end 20 on the surface of the layer 13f is configured to protrude by about 0.5 to 1.0 mm.

  The extraction electrode 18 and the extraction electrode 19 are formed in contact with part of the protruding electrode layer 13a and electrode layer 13f.

  In the above configuration, by setting the thickness of the first support 11 to 6 μm or more, the electrode layer 13a on the first support 11 is formed by the pressure at the time of formation of the extraction electrode 18 and extraction electrode 19 by metallicon, The end portion 20 on the surface of the electrode layer 13f does not fall down, so that sufficient connection with the extraction electrode 18 and the extraction electrode 19 is ensured at the end portion 20.

  As a result, even after the extraction electrode 18 and the extraction electrode 19 are provided, the dielectric loss (tan δ) does not increase, and a film capacitor with good characteristics can be obtained.

  Furthermore, since the thickness of the 2nd support body 14 is made thinner than the thickness of the 1st support body 11 6 micrometers or more, the shape of a film capacitor is not enlarged.

  Specific examples will be described below.

  In the following examples, the thickness of the second support 14 is set to 5 μm, the thickness of the first support 11 is changed, and the electrode layer 13 and the electrode layer 16 are wound so as to face each other through the dielectric film 17. After that, a film capacitor in which the extraction electrode 18 and the extraction electrode 19 were formed on both end faces by metallicon was produced, and the dielectric loss was measured.

  Each of the produced film capacitor samples has a rated voltage of 2200 V, an electrostatic capacity of 0.017 μF, and a dimension-defined value of a wound outer diameter (outer diameter after winding) of 2.27 cm or less.

  A PP film is used as the material of the first and second supports 11 and 14, and a PP film having a thickness of 12 μm is used as the dielectric film 17 because of the rated voltage.

Example 1
The thickness of the first support 11 was 6 μm, the thickness of the second support 14 was 5 μm, and it was wound together with a 12 μm dielectric film as shown in FIG. 1 to form extraction electrodes 18 and extraction electrodes 19 on both end faces. 100 film capacitor samples were prepared. With respect to this sample, a dielectric loss (tan δ) was measured by applying a voltage of 10 kHz 1 V at 25 ° C., and the ratio of the number of samples having tan δ of 0.03% or more was defined as a defect rate.

  The defect rate of 100 samples according to Example 1 (the ratio of the number of samples with tan δ being 0.03% or more) was 10%.

  The outer diameter of the film capacitor sample was 2.17 cm, which was within the range of the stipulated value.

(Example 2)
100 film capacitor samples were produced in the same manner as in Example 1 except that the thickness of the first support 11 was set to 7 μm, and the result of measuring the tan δ defect rate was 5%.

  The outer diameter of the sample of Example 2 was 2.22 cm, which was also within the range of the dimension specification value.

(Example 3)
100 film capacitor samples were produced in the same manner as in Example 1 except that the thickness of the first support 11 was 8 μm, and the result of measuring the tan δ defect rate was 2%.

  However, as the thickness of the first support 11 is increased, the shape of the film capacitor is increased, the wound outer diameter is 2.27 cm, and the size of Example 3 is the limit of the stipulated dimension value.

(Comparative Example 1)
Except that the thickness of the first support 11 was set to 5 μm, 100 film capacitor samples were produced in the same manner as in Example 1, and the result of measuring the defective rate of tan δ was 40%.

  Moreover, when the cross section of the film capacitor sample of Examples 1-3 and the comparative example 1 was observed, the fall of the 1st support body 11 was the largest in the sample of the comparative example 1, and Examples 1-3 and the 1st support. As the thickness of the body 11 was increased, the degree of the collapse was reduced.

  As apparent from the above results, the defect rate of the dielectric loss (tan δ) of the film capacitor is reduced by making the thickness of the first support 11 thicker than that of the second support 14 and 6 μm or more. The film capacitor can withstand high withstand voltage and large current.

  Here, as the thickness of the first support 11 is thicker, the collapse is reduced and the defective rate of tan δ tends to be reduced, but the outer diameter of the film capacitor is increased.

  In order to compensate for this, it is conceivable to reduce the thickness of the second support 14. However, the thinner the thickness, the harder it is to withstand the heat during metal vapor deposition, and the metal vapor deposition electrodes on both sides as in the present embodiment. In the case of forming, the influence of heat during metal deposition is further increased.

  For this reason, there exists a limit in making the thickness of the 2nd support body 14 thin, and it is preferable to set it as 3-4 micrometers or more.

  Therefore, it is more preferable that the thickness of the first support 11 is 6 μm or more and 8 μm or less, and the thickness of the second support 14 is 3 μm or more and 5 μm or less.

  Moreover, in this Embodiment, it is comprised so that the edge part 20 of the surface of the electrode layers 13a, 13c, 13d, and 13f on the 1st support body 11 may protrude about 0.5-1.0 mm.

  When the width of the projecting end portion 20 is shorter than 0.5 mm, the first support 11 is easily supported by the adjacent dielectric film or the second support 14. Although the degree of falling is reduced, since the width of the end portion 20 is short, the contact portions with the extraction electrode 18 and the extraction electrode 19 are reduced.

  Furthermore, since the unevenness of both end faces when wound is reduced, the surface area of both end faces is reduced, and as a result, the adhesive strength of the extraction electrode is also lowered.

  If the width of the end portion 20 is longer than 1 mm, the contact portion between the extraction electrode 18 and the extraction electrode 19 increases, but the first support 11 is adjacent to the adjacent dielectric film or the second support 14. It becomes difficult to support, and the degree to which the first support 11 falls down during metal spraying increases.

  Therefore, the width of the end portion 20 is preferably 0.5 to 1.0 mm.

  In the present embodiment, PP films are used as the first and second supports 11 and 14, but other organic films such as PET films can also be used.

  The PET film is higher in strength than the PP film and hardly affected by the pressure during metal spraying, but the film itself has a high dielectric loss (tan δ). For example, the PET film is formed symmetrically on both surfaces of the first support 11. If there is a deviation in the positions of the metal layer 16a and the metal layer 16d, a capacitance component having a large tan δ is generated at this deviation portion, which may lead to an increase in tan δ of the entire film capacitor.

  For this reason, it is preferable to use a PP film having a relatively small dielectric loss as the first support 11 and the second support 14.

  Since the dielectric film 17 is a film that functions as a dielectric, a PP film having a small tan δ of the film itself is preferable.

  In this embodiment, the electrode layer formed on both sides of the support and the dielectric film not formed with the electrode layer are wound. However, the present invention is not limited to this, and the conventional structure shown in FIG. Even when the upper film 22 and the lower film 23 are wound as in the example, the same effect can be obtained by making the upper film 22 thicker than the lower film 23 and 6 μm or more.

  In FIG. 1, the gap between the first and second supports 11 and 14 and the dielectric film 17 is exaggerated for the sake of explanation. However, in an actual film capacitor, these are extremely close to each other. Or are in close contact.

  In the film capacitor of the present invention, the thickness of the first support forming the electrode layer whose both ends in the width direction are connected to the extraction electrode is thicker than the other second support and 6 μm or more. Therefore, the increase in dielectric loss (tan δ) is suppressed and the film capacitor with improved characteristics can be obtained by reducing the collapse of the support during metal spraying without increasing the size of the film capacitor. It is useful for a film capacitor for high withstand voltage.

Sectional drawing of the film capacitor by embodiment of this invention Perspective view of a conventional series capacitor Equivalent circuit diagram of conventional metalized film capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 1st support body 12 and 15 Non-deposition part 13a, 13b, 13c, 13d, 13e, 13f Electrode layer 14 2nd support body 16a, 16b, 16c, 16d Electrode layer 17 Dielectric film 18, 19 Extraction electrode 20 End portion 21a, 21b Electrode extraction portion 22 Upper layer film 23 Lower layer film 24 Insulating groove portion 25a, 25b Strip electrode 26 Insulating groove portion 27 Strip electrode

Claims (2)

Forming a long first support body having a plurality of longitudinally extending electrode layers insulated from each other, a dielectric film not forming an electrode layer, and a plurality of longitudinally extending electrode layers insulated from each other A film capacitor in which a plurality of capacitor elements are connected in series by forming take-out electrodes on both end faces thereof, Among the electrode layers on one support, electrode layers at both ends in the width direction of the support are connected to the extraction electrode, and the thickness of the first support is larger than the thickness of the second support. A film capacitor characterized by being thick and 6 μm or more. The film capacitor according to claim 1, wherein the first support, the second support, and the dielectric film are polypropylene films.

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