JP2015211071A - Film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film capacitor that can be made compact, and can have a high capacity, by reducing the volume ratio of a metallicon electrode.SOLUTION: In a film capacitor including a wound body 2 formed by winding at least a pair of dielectric films 4a, 4b having electrode films 5a, 5b on the surface, and a pair of metallicon electrodes 3a, 3b provided at the opposite ends of the wound body 2, the wound body 2 has an effective part 2c the electrode films 5a, 5b of the pair of dielectric films 4a, 4b are superposed each other, and a pair of margin parts 2a, 2b including any one of the electrode films 5a, 5b, and interposed between the effective part 2c and the and metallicon electrodes 3a, 3b. The diameter d1 of the effective part 2c in a cross-section perpendicular to the winding axis X of the wound body 2 is made larger than the diameter d2 of the metallicon electrodes 3a, 3b.

Description

  The present invention relates to a film capacitor.

  A film capacitor is a metallized film that uses an electrode film by depositing a metal such as aluminum on the surface of the dielectric film. Self-healing performance specific to the electrode film (when a short circuit occurs in an insulation defect, Since the electrode film around the defective portion is evaporated and scattered by the short-circuit energy to insulate and recover the function of the capacitor), it has been widely used because of its high reliability against dielectric breakdown.

  Such a film capacitor is obtained by stacking and winding two metallized films while being shifted from each other, and forming metallicon electrodes at both ends in the width direction of the film. For example, in Patent Document 1, for the purpose of improving the connection strength between the metal surface of the metallized film and the metallicon electrode, the vapor deposition surface of the metal surface is oriented in the direction of thermal spraying of the metallicon at both ends of the metallized film. It is tilted.

JP 2013-138046 A

  However, in the film capacitor described in Patent Document 1, the outer diameter of the metallicon electrode is about the same as the outer diameter of the wound body around which the metallized film is wound, and the volume ratio of the metallicon electrode to the wound body is large. There was a problem that it was difficult to reduce the size and increase the capacity of the capacitor.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a film capacitor that can be easily reduced in size and increased in capacity by reducing the volume ratio of the metallicon electrode.

  The film capacitor of the present invention is a film capacitor comprising a wound body obtained by winding at least a pair of dielectric films having electrode films on the surface, and a pair of metallicon electrodes provided at both ends of the wound body. The wound body includes an effective portion in which the electrode films of the pair of dielectric films overlap each other and the electrode film, and a pair of margins interposed between the effective portion and the metallicon electrode. And the diameter of the effective portion is larger than the diameter of the metallicon electrode in a cross section perpendicular to the winding axis of the winding body.

  ADVANTAGE OF THE INVENTION According to this invention, the volume ratio of a metallicon electrode can be reduced and the film capacitor which can be easily reduced in size and increased in capacity can be provided.

It is a perspective view which shows typically the main body of the film capacitor which is one Embodiment of this invention. It is a perspective view which shows typically the state which wound the film with a set of electrode films. (A) of the film capacitor which is one Embodiment of this invention is explanatory drawing which shows the dimension of each part, (B) is an enlarged view of the cross section in the part enclosed with the broken line of (A). It is explanatory drawing of the film capacitor which is one Embodiment of this invention. (A) of the film capacitor which is another embodiment of this invention is explanatory drawing which shows the dimension of each part, (B) is an enlarged view of the cross section in the part enclosed with the broken line of (A). (A) of the film capacitor which is another embodiment of this invention is explanatory drawing which shows the dimension of each part, (B) is an enlarged view of the cross section in the part enclosed with the broken line of (A). (A) of the film capacitor which is another embodiment of this invention is explanatory drawing which shows the dimension of each part, (B) is an enlarged view of the cross section in the part enclosed with the broken line of (A).

  Embodiments of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below is an example of the present invention, and various modifications can be made without departing from the gist of the present invention.

  As shown in FIG. 1, the film capacitor of the present embodiment includes a wound body 2 formed by winding a film 1 with an electrode film, and a pair of metallicon electrodes 3 a and 3 b provided at both ends of the wound body 2. ing.

  Moreover, as shown in FIG. 2, the film 1 with an electrode film is one in which an electrode film 5 having conductivity is provided on one surface of a dielectric film 4, and is a dielectric film 4a provided with an electrode film 5a. A wound body 2 is formed by winding at least a pair of the film with electrode film 1 as a pair of a film with electrode film 1a and a film with electrode film 1b which is a dielectric film 4b having the electrode film 5b. Has been. On one end of the dielectric film 4 in the width direction (direction of the winding axis X), there is a region where the electrode film 5 is not provided. The pair of films 1a, 1b with electrode film are overlapped and wound so that regions where the electrode films 5a, 5b are not provided are located on different end sides. Such a wound body 2 includes a pair of effective portions 2c in which the electrode film 5a and the electrode film 5b overlap with each other via the dielectric films 4a and 4b, and only one of the electrode film 5a and the electrode film 5b. Margin portions 2a and 2b are provided. The margin portion 2a is interposed between the effective portion 2c and the metallicon electrode 3a, and the margin portion 2b is interposed between the effective portion 2c and the metallicon electrode 3b (see FIG. 1). The electrode films 5a and 5b in the margin portions 2a and 2b are exposed at different end portions of the wound body 2, and are electrically connected to the metallicon electrodes 3a and 3b, respectively.

  In the film capacitor of this embodiment, as shown in FIG. 3A, the diameter of the effective portion 2c is d1 and the diameters of the metallicon electrodes 3a and 3b are d2 in a cross section perpendicular to the winding axis X of the winding body 2. D1 is larger than d2. Thus, by making the diameter d1 of the effective portion 2c larger than the diameter d2 of the metallicon electrodes 3a and 3b, the volume ratio of the metallicon electrodes 3a and 3b to the wound body 2 can be reduced, and the film capacitor can be made compact. Therefore, the influence of the metallicon electrodes 3a and 3b can be reduced when the capacity and capacity are increased. In addition, the sprayed area of the metal is reduced, the efficiency of spraying is improved, and the cost can be reduced.

  Here, the diameter d1 of the effective portion 2c is at least the diameter of the effective portion 2c in the direction perpendicular to the winding axis X using a micrometer, a caliper or the like, or using a photograph of a cross section perpendicular to the winding axis X. Two points are measured and the largest of the data obtained by the measurement. Further, the diameter d2 of the metallicon electrodes 3a and 3b is the diameter of the largest portion of the metallicon electrodes 3a and 3b in the direction perpendicular to the winding axis X, using a micrometer, a caliper or the like, or the winding axis X At least two points are measured using a photograph of a cross section perpendicular to, and it is assumed that the data obtained by the measurement is the largest. Hereinafter, the diameter is a diameter in a direction perpendicular to the winding axis X unless otherwise specified.

  The ratio d2 / d1 of d2 to d1 is preferably in the range of 0.85 to 0.99. By setting d2 / d1 to 0.99 or less, the volume ratio of the metallicon electrodes 3a and 3b to the wound body 2 is reduced, and the film capacitor can be easily reduced in size and increased in capacity. Moreover, although mentioned later for details, malfunctions, such as peeling in the peripheral part of metallicon electrode 3a, 3b, can be reduced. By setting d2 / d1 to 0.85 or more, the bonding strength between the electrode films 5a and 5b and the metallicon electrodes 3a and 3b can be increased.

  The margin portions 2a and 2b are closer to the end portion side of the wound body 2 than the diameter on the effective portion 2c side, that is, the diameter on the metallicon electrode 3a side in the margin portion 2a, and the diameter on the metallicon electrode 3b side in the margin portion 2b. It is preferable to have a smaller tapered portion. Since the margin portions 2a and 2b have such a tapered portion, stress due to deformation of the dielectric film 4 and the electrode film 5 is reduced between the effective portion 2c having different diameters and the metallicon electrodes 3a and 3b. And the occurrence of defects can be suppressed.

  Here, when the length of the wound body 2 in the winding axis X direction is L1, and the length of the tapered portion is L2, the ratio L2 / L1 of L2 to L1 is in the range of 0.05 to 0.30. Preferably there is. By setting L2 / L1 to 0.05 or more, d2 of the metallicon electrodes 3a and 3b can be made smaller than the effective layer 2c, and by setting L2 / L1 to 0.30 or less, sufficient electrostatic capacity can be obtained. Capacity can be secured.

  Such a film capacitor may be produced, for example, as follows. First, the dielectric film 4 is prepared. The dielectric film 4 is obtained by, for example, forming a resin solution obtained by dissolving an insulating resin in a solvent into a sheet shape on the surface of a base material made of, for example, polyethylene terephthalate (PET), and drying to volatilize the solvent. It is done. The forming method may be appropriately selected from known film forming methods such as a doctor blade method, a die coater method, and a knife coater method. Solvents used for molding include, for example, methanol, isopropanol, n-butanol, ethylene glycol, ethylene glycol monopropyl ether, methyl ethyl ketone, methyl isobutyl ketone, xylene, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dimethylacetamide, cyclohexane Alternatively, an organic solvent containing a mixture of two or more selected from these may be used. Further, a resin film produced by a melt extrusion method may be stretched.

  The thickness of the dielectric film 4 may be, for example, 5 μm or less, but it is particularly preferable to use the dielectric film 4 having a thickness of 0.5 to 2 μm.

  Examples of the insulating resin material used for the dielectric film 4 include polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), and cycloolefin polymer (COP). . Cycloolefin polymer (COP) is particularly preferable because of its high dielectric breakdown voltage.

The dielectric film 4 may be made of only the above-described insulating resin, but may contain other materials. Examples of components other than the resin contained in the dielectric film 4 include the organic solvents and inorganic fillers described above. As the inorganic filler, for example, inorganic oxides such as alumina, titanium oxide, and silicon dioxide, inorganic nitrides such as silicon nitride, glass, and the like can be used. In particular, when a material having a high relative dielectric constant such as a composite oxide having a perovskite structure is used as the inorganic filler, the relative dielectric constant of the entire dielectric film 4 is improved, and the film capacitor can be reduced in size. In order to improve the compatibility between the inorganic filler and the resin, the inorganic filler may be subjected to a surface treatment such as a silane coupling treatment or a titanate coupling treatment.

  When such an inorganic filler is used for the dielectric film 4, a composite film containing less than 50% by mass of the inorganic filler and 50% by mass or more of the resin is used to maintain the flexibility of the resin. Effects such as improvement of relative dielectric constant can be obtained. Moreover, it is preferable that the size (average particle diameter) of an inorganic filler shall be 4-1000 nm.

  A film 1 with an electrode film provided with an electrode film 5 is formed by depositing a metal component such as aluminum (Al) on one main surface of the produced dielectric film 4 after masking one end in the width direction. prepare.

  Examples of the material of the electrode film 5 include metals and alloys such as aluminum (Al) and zinc (Zn). The thickness of the electrode film 5 is preferably 5 to 100 nm, particularly 10 to 80 nm.

  Next, the mask is removed from the film with electrode film 1 to form a pair of the film with electrode film 1a and the film with electrode film 1b, and the electrode film 5a of the film with electrode film 1a and the electrode film 5b of the film with electrode film 1b are formed. The winding body 2 is obtained by superimposing the main surface so as to face the main surface which is not formed and applying a predetermined tension using a winding machine. At this time, the films with electrode films 1a and 1b are overlapped so that the regions where the electrode films 5a and 5b are not formed by the mask are located on different end sides. Moreover, it is preferable to wind the films 1a and 1b with electrode films so that the surfaces on which the electrode films 5a and 5b are provided are on the outer peripheral side as shown in FIG.

  Here, the thickness of the dielectric film 4 and the electrode film 5 is increased by using the film with electrode film 1 having a thickness of the dielectric film 4 of 2 μm or less and a thickness of the electrode film 5 of 10 to 80 nm. And the influence of the thickness of the electrode film 5 on the diameter of the wound body 2 increases. That is, a pair of margin portions including only one of the electrode film 5a and the electrode film 5b with respect to the diameter d1 of the effective portion 2c where the electrode film 5a and the electrode film 5b overlap with each other via the dielectric films 4a and 4b The diameters of 2a and 2b tend to be small. Accordingly, the difference between the diameter d1 of the effective portion 2c and the diameters of the margin portions 2a and 2b is increased, and the margin portion 2a is wound by winding the films with electrode films 1a and 1b while applying a predetermined tension as described above. And the diameter of 2b becomes small, so that the distance from the effective part 2c becomes large, and a taper part is formed in the margin parts 2a and 2b.

  The film with electrode film 1 may be wound using a core, or the metallized film 1 may be wound in a cylindrical shape without using a core. The diameters of the margin portions 2a and 2b may be further reduced by pressing the wound wound body 2. When a winding core is used, it is preferable to remove the winding core from the wound body 2 from the viewpoint of reducing the volume of the film capacitor.

  In the present embodiment, the margin portions 2a and 2b are entirely tapered, but the margin portions 2a and 2b may be tapered as shown in FIGS. I do not care. For example, in the form of FIG. 5, as shown in FIG. 5B, the tapered portion of the margin portion 2b is formed on the metallicon electrode 3b side of the margin portion 2b. In the embodiment of FIG. 6, as shown in FIG. 6B, the tapered portion of the margin portion 2b is formed on the effective layer 2c side of the margin portion 2b. In the form of FIG. 7, as shown in FIG. 7B, the tapered portion of the margin portion 2b is not in contact with either the effective layer 2c or the metallicon electrode 3b between the effective layer 2c and the metallicon electrode 3b. Is formed. Such a form can be realized, for example, by adjusting the flexibility of the dielectric film 4 or by adjusting the shapes of the margin portions 2a and 2b when the wound body 2 is pressed.

  When the tapered portion is formed in the effective portion 2c, the electrode film 5b located near the margin portion 2a or the electrode film 5a located near the margin portion 2b is peeled off from the dielectric film 4b or 4a, Since there is a concern that the capacitance decreases or varies, the tapered portion is preferably formed in the margin portions 2a and 2b.

  Next, metallicon electrodes 3a and 3b are formed at the ends of the wound body 2 where the electrode film 5a and the electrode film 5b are exposed, respectively. Metallicon electrodes 3a and 3b are formed by spraying a metal such as zinc (Zn) or aluminum (Al) on the end of wound body 2. At this time, the margin portions 2a and 2b have a tapered portion in which the diameter on the end portion side of the wound body 2 is smaller than the diameter on the effective portion 2c side, that is, the diameter on the metallicon electrodes 3a and 3b side is smaller. Thus, the diameters of the metallicon electrodes 3a and 3b can be made smaller than the diameter of the effective portion 2c.

  When forming the metallicon electrode 3, the plurality of wound bodies 2 are arranged so that the end portions thereof are directed in the spraying direction, and simultaneously sprayed. At that time, the diameters of the effective portion 2c and the margin portions 2a and 2b are the same, or the margin portions 2a and 2b are reversely tapered (the diameter of the end portion side of the wound body 2 is larger than the diameter of the effective portion 2c side). When the winding bodies 2 are arranged so as to be in close contact with each other, the metallicon electrodes 3 formed on the adjacent winding bodies 2 are joined together and separated from each other when the metallicon electrodes 3 are separated. Problems such as partial or complete peeling occur. Therefore, it is possible to prevent the metallicon electrodes 3 formed on the adjacent wound bodies 2 from being joined together by arranging a plurality of wound bodies 2 via spacers or the like so that the wound bodies 2 are not in close contact with each other. In addition, the number of wound bodies 2 that can be sprayed simultaneously decreases, and the efficiency of the spraying process decreases.

  When the margin portions 2a and 2b have a tapered portion having a small diameter on the end side of the wound body 2 as in the present embodiment, even if the plurality of wound bodies 2 are arranged so as to be in close contact, the metallicon electrode 3 At the end portion of the wound body 2 where the metal body is formed, a gap is formed between the end portions of the adjacent wound bodies 2, and the metallicon electrodes 3 formed on the adjacent wound bodies 2 are difficult to be joined to each other. . Therefore, it is possible to efficiently form the metallicon electrode 3 free from defects. In the thermal spraying process, the taper portion of the wound body 2 may be masked with a cover tape or the like so that the metallicon electrode 3 is formed only at the end portion.

  When forming the metallicon electrodes 3a and 3b, the lead wires 6a and 6b may be joined to the metallicon electrodes 3a and 3b at the same time as shown in FIG. For example, a copper wire may be used as the lead wire.

  Next, the film capacitor can be obtained by forming the exterior member 7 made of resin on the surface of the main body of the film capacitor on which the metallicon electrodes 3a and 3b (including the lead wires 6a and 6b) are formed. For ease of understanding, in FIG. 4, the exterior member 7 is indicated by a broken line, and the main body of the film capacitor inside is indicated by a solid line.

  In the present embodiment, the main body of the film capacitor has been described as having a circular cross section perpendicular to the winding axis X. However, an elliptical shape or a polygonal shape may be used. In that case, the major axis of the cross section or the length of the diagonal line is regarded as the diameter.

1, 1a, 1b: Film with electrode film 2: Rolled body 2a, 2b: Margin portion of wound body 2c: Effective portion of wound body 3, 3a, 3b: Metallicon electrode 4, 4a, 4b: Dielectric film 5, 5a, 5b: Electrode film 6a, 6b: Lead wire 7: Exterior member

Claims (2)

A film capacitor comprising a wound body formed by winding at least a pair of dielectric films having electrode films on the surface, and a pair of metallicon electrodes provided at both ends of the wound body,
The wound body includes an effective portion in which the electrode films of the pair of dielectric films overlap each other, and a pair of margin portions interposed between the effective portion and the metallicon electrode. And having
A film capacitor, wherein a diameter of the effective portion is larger than a diameter of the metallicon electrode in a cross section perpendicular to a winding axis of the wound body. 2. The film capacitor according to claim 1, wherein the margin portion has a tapered portion whose diameter on the metallicon electrode side is smaller than the diameter on the effective portion side in a cross section perpendicular to the winding axis. .

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