Film capacitor element and film capacitor

Abstract

Included are: a main unit in which a plurality of dielectric films, and first electrode films and second electrode films, are laminated or wound; and a first external electrode electrically connected to the first electrode films and a second external electrode electrically connected to the second electrode films, the external electrodes being provided on respective ends of the main unit. The main unit has capacitance portions, at which the first electrode films and the second electrode films face each other across the dielectric films, and gaps are provided between the dielectric films and the first electrode films or the second electrode films at the capacitance portions.

Description

[Technical field]

[0001] The present disclosure relates to a film capacitor element and a film capacitor including the same. [Background technology]

[0002] An example of the prior art is described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-211071 A Summary of the Invention

[0004] A film capacitor element according to one embodiment of the present disclosure includes: A body in which a dielectric film, a first electrode film, and a second electrode film are laminated or wound in a plurality of layers; a first external electrode provided on both ends of the body and electrically connected to the first electrode film and a second external electrode electrically connected to the second electrode film, the main body has a capacitance section in which the first electrode film and the second electrode film face each other with the dielectric film interposed therebetween, In the capacitance portion, there is a gap between the dielectric film and the first electrode film or the second electrode film.

[0005] Further, a film capacitor according to one aspect of the present disclosure includes the film capacitor element, a housing in which the film capacitor element is housed; and a sealant that seals the film capacitor element housed in the housing. [Brief description of the drawings]

[0006] The objects, features and advantages of the present disclosure will become more apparent from the following detailed description and drawings.

[0007] [Figure 1] 1 is a diagram illustrating a cross section of a film capacitor element according to an embodiment of the present disclosure cut along a plane along a first direction X. FIG. [Figure 2A] 11A to 11C are diagrams for explaining a procedure for expanding gas such as air remaining in an electrode film-forming film. [Figure 2B] 11A to 11C are diagrams for explaining a procedure for vaporizing and expanding a solvent remaining in an electrode film-forming film. [Diagram 3] 1 is a diagram showing a state in which a film capacitor element is exteriorly covered with resin. [Figure 4] 10 is a diagram showing a schematic diagram of the pressure of resin acting on a film capacitor element when the film capacitor element is exterior-wrapped with resin. FIG. [Diagram 5] 1 is a cross-sectional view illustrating a schematic diagram of a film capacitor according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The basic configuration of this disclosure discloses a film capacitor element and a film capacitor including a wound body formed by winding at least one pair of dielectric films having electrode films on their surfaces, and a pair of metallikon electrodes provided on both ends of the wound body. In this disclosure, the wound body has an effective portion where the electrode films of the pair of dielectric films overlap each other, and it is proposed that the diameter of the effective portion is made larger than the diameter of the metallikon electrodes in a cross section perpendicular to the winding axis of the wound body, thereby reducing the volume ratio of the metallikon electrodes and achieving a smaller size and higher capacity of the film capacitor.

[0009] An embodiment of the film capacitor element will be described below.

[0010]

[0023] The embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are merely examples of the present disclosure, and various modifications are possible without departing from the spirit and scope of the present disclosure.

[0011] FIG. 1 is a schematic diagram showing a cross section of a film capacitor element according to an embodiment of the present disclosure cut along a plane along a first direction X. The film capacitor element 1 includes a main body 20 in which a plurality of electrode film-forming films 6 each having dielectric films 2a, 2b and electrode films 4a, 4b formed on one surface of the dielectric films 2a, 2b are laminated or wound, and a pair of external electrodes 3a, 3b provided at both ends of the main body 20 in the first direction X and connected to the electrode films 4a, 4b of the plurality of electrode film-forming films 6, respectively, so that a capacitance section 20c (effective section) is formed in the first direction X intermediate section between both ends. The main body 20 has a gap S between the electrode film-forming films 6. That is, the plurality of dielectric films 2a, 2b are plastically deformed in a state in which the gap S is present in the lamination direction. The width of the gap S, i.e., the interval in the lamination direction between the electrode film-forming films 6 adjacent to each other across the gap S, is, for example, 0.5 μm or more. The width of the gap S may be, for example, one or more times the thickness of the dielectric films 2a and 2b, or may be two or more times the thickness of the dielectric films 2a and 2b. The electrode film-forming film 6 has a surface on which a plurality of minute recesses 7 are provided.

[0012] The recess 7 may be a hole having a circular, elliptical, polygonal, star-shaped, or other shape in plan view, or may be a groove having a linear, arcuate, dendritic, or other shape in plan view. The recess 7 may also have a shape in which two or more holes or grooves are connected. The depth of the recess 7 may be, for example, 10 nm or more and half or less of the thickness of the dielectric films 2a, 2b. When the recess 7 is a hole, the diameter of the recess 7 in plan view may be, for example, 10 nm or more and 2 μm or less. When the recess 7 is a groove, the width of the recess 7 in plan view may be, for example, 10 nm or more and 2 μm or less, and the length may be, for example, 200 μm or less. The density of the recess 7 may be, for example, 1 piece / mm 2 More than 1000 pieces / mm 2 It may be the following.

[0013] The recess 7 here refers to a hole having a diameter to depth ratio (diameter / depth) or a groove having a width to depth ratio (width / depth) of 3 or less.

[0014] Hereinafter, the dielectric films 2a, 2b may be simply referred to as the dielectric film 2, and the electrode films 4a, 4b may be simply referred to as the electrode film 4.

[0015] The film capacitor element 1 can be produced, for example, as follows. First, the dielectric film 2 is prepared. The dielectric film 2 is obtained by forming a resin solution, for example, in which an insulating resin is dissolved in a solvent, into a sheet on the surface of a base film made of, for example, polyethylene terephthalate (PET), and drying to volatilize the solvent. The forming method may be appropriately selected from well-known film forming methods such as a doctor blade method, a die coater method, and a knife coater method. Examples of the solvent used for forming include 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, and organic solvents containing a mixture of two or more selected from these. The dielectric film 2 can also be produced by stretching a resin film produced by a melt extrusion method.

[0016] The thickness of the dielectric film 2 may be, for example, 5 μm or less, and it is particularly preferable to use a dielectric film having a thickness of 0.5 to 2 μm.

[0017] Examples of insulating resins used for the dielectric film 2 include polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), polyarylate (PAR), polyphenylene ether (PPE), polyetherimide (PEI), and cycloolefin polymer (COP). Cycloolefin polymer (COP) is particularly preferred because of its high dielectric breakdown voltage.

[0018] The dielectric film 2 may be composed of only the insulating resin described above, but may also contain other materials. Examples of components other than the resin contained in the dielectric film 2 include the organic solvent and inorganic filler described above. Examples of the inorganic filler that can be used include inorganic oxides such as alumina, titanium oxide, and silicon dioxide, inorganic nitrides such as silicon nitride, and glass. In particular, when a material with a high relative dielectric constant, such as a complex oxide having a perovskite structure, is used as the inorganic filler, the relative dielectric constant of the entire dielectric film 2 is improved, and the film capacitor can be made smaller. In addition, 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.

[0019] FIG. 2A is a diagram for explaining a procedure for expanding gas such as air remaining in the electrode film-forming film 6. In FIG. 2A, the electrode film 4 is omitted for ease of illustration. For example, by heating a film capacitor element 1 in which an electrode film-forming film 6 having a plurality of minute recesses 7 is laminated, the air remaining in the minute recesses 7 can be expanded. The expanded air enters between the electrode film-forming films 6, forming voids S between the electrode film-forming films 6. The dielectric film 2 is plastically deformed with the voids S formed, and even if the film capacitor element 1 is cooled, the state in which the voids S are formed between the electrode film-forming films 6 is maintained.

[0020] The film capacitor element 1, on which the electrode film-forming film 6 having a plurality of minute recesses 7 is laminated, can be housed in a container, and the container housing the film capacitor element 1 can be evacuated to expand the air present in the minute recesses 7 of the electrode film-forming film 6. The expanded air gets into the gaps between the electrode film-forming films 6, forming voids S between the electrode film-forming films 6. Since the dielectric film 2 is plastically deformed with the voids S formed, the state in which the voids S are formed between the electrode film-forming films 6 can be maintained even if the pressure inside the container housing the film capacitor element 1 is set to atmospheric pressure.

[0021] In addition, by housing a film capacitor element 1 laminated with an electrode film-forming film 6 having a plurality of minute recesses 7 in a container, creating a vacuum inside the container housing the film capacitor element 1, and heating the film capacitor element 1, the air present in the recesses 7 of the electrode film-forming film 6 can be expanded even more easily.

[0022] FIG. 2B is a diagram for explaining the procedure for vaporizing the solvent remaining in the electrode film-forming film 6. In FIG. 2B, the electrode film 4 is omitted for ease of illustration. The film capacitor element 1 on which the electrode film-forming film 6 is laminated can be heated, for example, to vaporize the solvent remaining in the electrode film-forming film 6. The vaporized solvent penetrates between the electrode film-forming films 6, forming voids S between the electrode film-forming films 6. The dielectric film 2 is plastically deformed with the voids S formed, and even if the film capacitor element 1 is cooled, the state in which the voids S are formed between the electrode film-forming films 6 is maintained.

[0023] 3 is a diagram showing a state in which the film capacitor element 1 is sheathed with resin. The dimension of the expanded main body 20 in the lamination direction is L max The dimension of the external electrodes 3a and 3b in the lamination direction is l m As, L max -l m is defined as the maximum thickness difference, (L max -l m ) / l m ×100 is defined as the maximum expansion coefficient (%) in the lamination direction. Both the maximum thickness difference and the maximum expansion coefficient in the lamination direction are greater than 0. The maximum thickness difference may be, for example, greater than or equal to the thickness of the dielectric film 2, or greater than 0.5 μm. The maximum expansion coefficient in the lamination direction may be 100% or less, 50% or less, and particularly 25% or less. 5 denotes terminals connected to the external electrodes 3a and 3b, respectively.

[0024] 4 is a diagram showing a schematic diagram of the pressure of the resin acting on the film capacitor element 1 when the film capacitor element 1 is covered with the resin. In the dielectric film 2 of each layer, the capacitance portion 20c located between the pair of external electrodes 3a, 3b is plastically deformed so as to expand in the stacking direction, and a gap S is formed between the electrode film-forming films 6 of each layer. The pressure acting on the capacitance portion 20c in the stacking direction is alleviated by the presence of gas such as air in the gap S between the electrode film-forming films 6 of each layer. The gas present in the gap S may flow from the gap around the external electrodes 3a, 3b to the gap S of another layer. This further alleviates the pressure acting on the capacitance portion 20c.

[0025] This reduces the high pressure acting on the capacitance portion 20c in the stacking direction, and prevents the electrode film-forming films 6 from coming into contact with each other under high pressure, thereby preventing thermal damage to the electrode film-forming films 6, and thereby preventing the occurrence of short circuit breakdown.

[0026] The void S may be provided in at least a part of the stacking direction of the main body 20. The void S may extend across both ends of the main body 20 in the first direction X, or may be provided in a part between the both ends.

[0027] Fig. 5 is a cross-sectional view that typically illustrates a film capacitor according to an embodiment of the present disclosure. The film capacitor 100 includes the film capacitor element 1 according to the embodiment described above, a housing 10 that houses the film capacitor element 1, and a sealant 9 that seals the film capacitor element 1 housed in the housing 10. The sealant 9 is, for example, a resin. According to the film capacitor 100, a highly reliable film capacitor that is unlikely to suffer short circuit breakdown can be provided. Note that the film capacitor element is not limited to the film capacitor element 1 illustrated in Figs. 1 to 4, and other film capacitor elements may be used.

[0028] As another embodiment, the electrode films 4a, 4b are not formed on the dielectric films 2a, 2b, and the electrode films 4a, 4b and the dielectric films 2a, 2b are overlapped in an unbonded state and then laminated or rolled. Also, an electrode film-forming film 6 in which the electrode film 4a is formed on one surface of the dielectric film 2a and the electrode film 4b is formed on the other surface of the dielectric film 2a can be overlapped with a dielectric film 2b on which the electrode films 4a, 4b are not formed, and then laminated or rolled.

[0029] The present disclosure may have the following embodiments.

[0030] A film capacitor element according to one embodiment of the present disclosure includes: A body in which a dielectric film, a first electrode film, and a second electrode film are laminated or wound in a plurality of layers; a first external electrode provided on both ends of the body and electrically connected to the first electrode film and a second external electrode electrically connected to the second electrode film, the main body has a capacitance section in which the first electrode film and the second electrode film face each other with the dielectric film interposed therebetween, In the capacitance portion, there is a gap between the dielectric film and the first electrode film or the second electrode film.

[0031] Further, a film capacitor according to one aspect of the present disclosure includes the film capacitor element, a housing in which the film capacitor element is housed; and a sealant that seals the film capacitor element housed in the housing.

[0032] According to the film capacitor element and film capacitor of the present disclosure, short circuit breakdown can be suppressed and reliability can be improved.

[0033] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-mentioned embodiments, and various modifications and improvements are possible within the scope of the gist of the present disclosure. It goes without saying that all or part of the components of each of the above-mentioned embodiments can be appropriately combined within the scope of not contradicting each other. [Explanation of symbols]

[0034] 100 Film Capacitor 1 Film capacitor element 2a, 2b Dielectric film 3a,3b External electrode 4a,4b Electrode film 20 Main unit 20c capacity part 6 Electrode film forming film 9. Encapsulating materials S void

Claims

1. A body in which a dielectric film, a first electrode film, and a second electrode film are laminated or wound in a plurality of layers; a first external electrode provided on both ends of the body and electrically connected to the first electrode film and a second external electrode electrically connected to the second electrode film, the main body has a capacitance portion in which the first electrode film and the second electrode film face each other with the dielectric film interposed therebetween, In the capacitance section, a gap is provided between the dielectric film and the first electrode film or the second electrode film, The first electrode film or the second electrode film is further provided on one surface of the dielectric film, The surfaces of the plurality of electrode film-forming films have a plurality of minute recesses.

2. The film capacitor element according to claim 1 , wherein the width of the gap in the lamination direction is equal to or greater than the thickness of the dielectric film.

3. The film capacitor element according to claim 1 or 2, a housing in which the film capacitor element is housed; and a sealing material that seals the film capacitor element housed in the housing.

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