Film capacitor

Abstract

The present disclosure addresses the problem of providing a film capacitor with which it is possible to improve voltage resistance. This film capacitor (100) is provided with a capacitor main body (1) in which two metallized films (3) are stacked and wound or alternately laminated. In a first metallized film (31), a metal oxide layer (6) is disposed on the upper surface side or the lower surface side of a first metal layer (71), a dielectric film (41 or 42) is disposed so as to face a surface of the first metal layer, the surface being opposite to the surface that is in contact with the metal oxide layer, and the dielectric breakdown voltage of the dielectric film that faces the first metal layer on which the metal oxide layer is disposed is higher than the dielectric breakdown voltage of the dielectric film that faces the metal oxide layer.

Description

Film capacitor

[0001] This disclosure relates to film capacitors in general, and more specifically to film capacitors that utilize film as a dielectric.

[0002] Patent Document 1 discloses a metallized film capacitor. This metallized film capacitor consists of a pair of metallized films, each having a metal vapor-deposited electrode formed on a dielectric film, and an element formed by winding or laminating these metallized films so that the respective metal vapor-deposited electrodes on the pair of metallized films face each other through the dielectric film, and a pair of metallicon electrodes formed on both end faces of this element. At least one of the metal vapor-deposited electrodes of the pair of metallized films is mainly composed of aluminum and has an oxide film layer formed at the junction with the dielectric film and a magnesium-containing layer formed on this oxide film layer, with the atomic concentration ratio of magnesium being highest in the magnesium-containing layer.

[0003] However, there is a need to improve the voltage resistance of the aforementioned film capacitors.

[0004] Japanese Patent Publication No. 2013-65747

[0005] The objective of this disclosure is to provide a film capacitor that can achieve improved voltage resistance.

[0006] A film capacitor according to one aspect of the present disclosure comprises a capacitor body formed by winding together a first metallized film and a second metallized film, or by alternately stacking the first metallized film and the second metallized film. The first metallized film includes a first dielectric film, a first metal oxide layer, and a first metal layer. The first dielectric film has a first upper surface and a first lower surface opposite to the first upper surface. The first metal oxide layer and the first metal layer are arranged on the first upper surface in order from the first upper surface. The second metallized film includes a second dielectric film and a second metal layer. The second dielectric film has a second upper surface and a second lower surface opposite to the second upper surface. The second metal layer is arranged on the second upper surface. The first metallized film and the second metallized film are stacked together such that the first upper surface side and the second lower surface side face each other. The dielectric breakdown voltage of the second dielectric film is higher than that of the first dielectric film.

[0007] A film capacitor according to one aspect of the present disclosure comprises a capacitor body formed by winding together a first metallized film and a second metallized film, or by alternately stacking the first metallized film and the second metallized film. The first metallized film includes a first dielectric film, a first metal oxide layer, and a first metal layer. The first dielectric film has a first upper surface and a first lower surface opposite to the first upper surface. The first metal layer and the first metal oxide layer are arranged on the first upper surface in order from the first upper surface. The second metallized film includes a second dielectric film and a second metal layer. The second dielectric film has a second upper surface and a second lower surface opposite to the second upper surface. The second metal layer is arranged on the second upper surface. The first metallized film and the second metallized film are stacked so that the first upper surface side and the second lower surface side face each other. The dielectric breakdown voltage of the first dielectric film is higher than that of the second dielectric film.

[0008] Figure 1 is a schematic cross-sectional view showing a film capacitor according to the first embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view showing a film capacitor according to the second embodiment of the present disclosure.

[0009] 1. Overview The film capacitor 100 according to the embodiment will be described with reference to the figures. Note that each figure is a schematic diagram, and the ratios of the size and thickness of each component in each figure do not necessarily reflect the actual dimensional ratios. Also, the arrows indicating each direction in each figure are not intended to define the direction in which the film capacitor 100 is used, but are merely indicated to make the explanation easier to understand and do not represent actual dimensions. The first direction D1 is the short side direction (width direction) of the dielectric film 4 and is sometimes called the "left-right direction". The third direction D3 is the thickness direction of the dielectric film 4 and is sometimes called the "up-down direction". In this embodiment, although not shown in the figures, the direction perpendicular to the first direction D1 and the third direction D3 is called the second direction D2. The second direction D2 is the longitudinal direction of the dielectric film 4. The first direction D1, the second direction D2, and the third direction D3 are mutually orthogonal.

[0010] The film capacitor 100 according to this embodiment comprises a capacitor body 1 formed by stacking two metallized films 3. The capacitor body 1 may be of the wound type or the laminated type. That is, it may be formed by stacking and winding two metallized films 3 together, or by alternately laminating them. The metallized film 3 includes a dielectric film 4 and a metal layer 7 as constituent elements. In addition to the dielectric film 4 and the metal layer 7, the metallized film 3 may also include a metal oxide layer 6 as a constituent element.

[0011] In this embodiment, the metal oxide layer 6 is in contact with either the upper or lower surface of the metal layer 7 that is electrically connected to the negative electrode. The metal oxide layer 6 contains a metal oxide and has a high energy barrier. Therefore, it can suppress the movement of electrons emitted from the side of the metal layer 7 that is in contact with the metal oxide layer 6 that is electrically connected to the negative electrode.

[0012] On the other hand, in this embodiment, the dielectric film 4 is positioned in contact with the side of the metal layer 7 that is electrically connected to the negative electrode, opposite to the side that is in contact with the metal oxide layer 6. The dielectric breakdown voltage of the dielectric film 4 that is in contact with the metal layer 7 that is electrically connected to the negative electrode is higher than the dielectric breakdown voltage of the dielectric film 4 that is not in contact with the metal layer 7 that is electrically connected to the negative electrode. Therefore, the movement of electrons emitted from the side of the metal layer 7 that is opposite to the side that is in contact with the metal oxide layer 6 can be sufficiently suppressed.

[0013] In this embodiment, the movement of electrons emitted from the metal layer 7 electrically connected to the negative electrode can be restricted. Therefore, the voltage withstand capability of the film capacitor 100 can be improved.

[0014] 2. Details (1) First Embodiment (1.1) Film Capacitor A film capacitor 100 according to the first embodiment will be described. Figure 1 is an explanatory diagram showing the film capacitor 100 according to the first embodiment. Note that in order to make the following explanation easier to understand, Figure 1 shows the two metallized films 3 (first metallized film 31 and second metallized film 32) separated. That is, the first metallized film 31 and the second metallized film 32 are in direct contact.

[0015] The capacitor body 1 includes a first metallized film 31 and a second metallized film 32. For example, in the case of a wound-type film capacitor 100, the capacitor body 1 is formed by winding the first metallized film 31 and the second metallized film 32 together. In the case of a multilayer film capacitor 100, the capacitor body 1 is formed by alternately stacking the first metallized film 31 and the second metallized film 32.

[0016] The first metallized film 31 has a constant width in the first direction D1, extends in the second direction D2, and has thickness in the third direction D3. For example, the width of the first metallized film 31 is 5 mm or more and 120 mm or less, and the thickness of the first metallized film 31 is 1.5 μm or more and 10.0 μm or less. In this case, it becomes easier to achieve improved dielectric strength.

[0017] The first metallized film 31 includes a first dielectric film 41, a first metal oxide layer 61, and a first metal layer 71.

[0018] The first dielectric film 41 has a constant width in the first direction D1, extends in the second direction D2, and has a constant thickness in the third direction D3.

[0019] The first dielectric film 41 has two main surfaces 8, a first upper surface 81 and a first lower surface 82. The first upper surface 81 is the upper surface in the third direction D3. The first lower surface 82 is the surface opposite to the first upper surface 81. In other words, the first lower surface 82 is the lower surface in the third direction D3.

[0020] The thickness of the first dielectric film 41 is the distance between the first upper surface 81 and the first lower surface 82, and is not particularly limited, but for example, it is 1.0 μm or more and 10.0 μm or less. In this case, it is easier to improve the withstand voltage of the film capacitor 100.

[0021] The first dielectric film 41 is a film composed of a dielectric material. The dielectric material includes, for example, at least one selected from the group consisting of polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polycarbonate (PC), and polystyrene (PS). Among these, polypropylene (PP) or polyethylene terephthalate (PET) is preferred. In other words, it is preferable that the first dielectric film 41 includes at least one selected from the group consisting of polypropylene (PP) and polyethylene terephthalate (PET). In this case, the dielectric breakdown voltage of the first dielectric film 41 is increased. Therefore, the withstand voltage of the film capacitor 100 can be further improved.

[0022] The first metal oxide layer 61 includes an oxide of at least one metal selected from the group consisting of, for example, aluminum (Al), silicon (Si), zirconium (Zr), titanium (Ti), barium (Ba), calcium (Ca), and copper (Cu). Among these, aluminum oxide (AlO ｘ ) or silicon oxide (SiO ｘ) can be suitably used. Among aluminum oxides, Al ２ O ３ This is more preferably used. In other words, the first metal oxide layer 61 is Al ２ O ３ It is more preferable to include this. In this case, an improvement in withstand voltage is more easily achieved.

[0023] The thickness of the first metal oxide layer 61 is not particularly limited, but for example, it is 3 nm or more and 30 nm or less. If the thickness is 3 nm or more, the tunnel current generated in the film capacitor 100 can be suppressed. If the thickness is 30 nm or less, the electron avalanche generated in the film capacitor 100 can be suppressed.

[0024] The first metal layer 71 includes at least one selected from the group consisting of, for example, aluminum (Al), gold (Au), magnesium (Mg), zinc (Zn), tin (Sn), nickel (Ni), chromium (Cr), iron (Fe), copper (Cu), and titanium (Ti). Among these, aluminum (Al) is preferably used. In other words, it is preferable that the first metal layer 71 includes Al. In this case, it becomes easier to achieve improved dielectric strength.

[0025] The thickness of the first metal layer 71 is not particularly limited, but is, for example, 3 nm or more and 100 nm or less.

[0026] On the first upper surface 81, a first metal oxide layer 61 and a first metal layer 71 are arranged in order of proximity to the first upper surface 81. The first metal oxide layer 61 is in direct contact with the first upper surface 81. The first metal layer 71 is in direct contact with the first metal oxide layer 61. The first metal layer 71 may be arranged to cover the entire first metal oxide layer 61, or to cover a part of the first metal oxide layer. For example, the first metal layer 71 may be divided into multiple regions to partially cover the first metal oxide layer 61.

[0027] The second metallized film 32 has a constant width in the first direction D1, extends in the second direction D2, and has thickness in the third direction D3. For example, the width of the second metallized film 32 may be the same as the width of the first metallized film 31. The thickness range of the second metallized film 32 may be the same as that of the first metallized film 31, for example, 1.5 μm or more and 10.0 μm or less. However, the thickness of the second metallized film 32 is different from the thickness of the first metallized film 31.

[0028] The second metallized film 32 includes a second dielectric film 42 and a second metal layer 72.

[0029] The second dielectric film 42 has a constant width in the first direction D1, extends in the second direction D2, and has thickness in the third direction D3.

[0030] The second dielectric film 42 has two main surfaces 8, a second upper surface 83 and a second lower surface 84. The second upper surface 83 is the upper surface in the third direction D3. The second lower surface 84 is the surface opposite to the second upper surface 83. In other words, the second lower surface 84 is the lower surface in the third direction D3.

[0031] The thickness of the second dielectric film 42 is the distance between the second upper surface 83 and the second lower surface 84, and it is preferable that it has an appropriate thickness from the viewpoint of improving dielectric strength. The range of the thickness of the second dielectric film 42 may be the same as that of the first dielectric film 41, for example, 1.0 μm or more and 10.0 μm or less.

[0032] It is preferable that the thickness of the second dielectric film 42 and the thickness of the first dielectric film 41 satisfy a specific relationship. Specifically, in the first embodiment, the thickness of the second dielectric film 42 is greater than the thickness of the first dielectric film 41. In this case, it is easier to achieve an improvement in dielectric strength. It is preferable that the thickness of the second dielectric film 42 is 1.05 times or more the thickness of the first dielectric film 41, and more preferably 1.10 times or more. In this case, it is easier to achieve an improvement in dielectric strength.

[0033] The second dielectric film 42 can be constructed using the materials listed as dielectrics constituting the first dielectric film 41. The dielectrics constituting the first dielectric film 41 and the dielectrics constituting the second dielectric film 42 may be the same or different. From the viewpoint of improving the dielectric strength of the film capacitor 100, it is preferable that the second dielectric film 42 includes at least one selected from the group consisting of polypropylene (PP) and polyethylene terephthalate (PET). The dielectric breakdown voltage in this disclosure can be measured based on the method for measuring dielectric breakdown strength specified in JIS C2151:2019.

[0034] Furthermore, as already mentioned, the dielectric breakdown voltage of the dielectric film 4 in contact with the metal layer 7 electrically connected to the negative electrode is higher than the dielectric breakdown voltage of the dielectric film 4 not in contact with the metal layer 7 electrically connected to the negative electrode. Therefore, in the first embodiment, the dielectric breakdown voltage of the second dielectric film 42 is higher than the dielectric breakdown voltage of the first dielectric film 41.

[0035] Furthermore, from the viewpoint of improving dielectric strength, it is preferable that the dielectric breakdown potential gradient of the second dielectric film 42 is increased. For example, the dielectric breakdown potential gradient of the second dielectric film 42 is 500 V / m or more. In this case, it becomes easier to further improve dielectric strength. This dielectric breakdown potential gradient is preferably 600 V / m or more, and more preferably 700 V / m or more.

[0036] In this disclosure, the dielectric breakdown potential gradient is defined as the value obtained by dividing the dielectric breakdown voltage, determined by the method described above, by the thickness (measured using a micrometer).

[0037] Furthermore, it is preferable that the dielectric breakdown voltage gradient of the second dielectric film 42 and the dielectric breakdown voltage gradient of the first dielectric film 41 satisfy a specific relationship. Specifically, in the first embodiment, the dielectric breakdown voltage gradient of the second dielectric film 42 is higher than that of the first dielectric film 41. In this case, it becomes easier to further improve the withstand voltage property. The dielectric breakdown voltage gradient of the second dielectric film 42 is preferably 1.05 times or more, more preferably 1.10 times or more, and even more preferably 1.20 times or more of the dielectric breakdown voltage gradient of the first dielectric film 41. In this case, it becomes particularly easy to improve the withstand voltage property.

[0038] The second metal layer 72 can contain the metals that the first metal layer 71 can contain. Similar to the first metal layer 71, the second metal layer 72 preferably contains Al. In this case, it becomes easier to improve the withstand voltage property.

[0039] The second metal layer 72 is disposed on the second upper surface 83. The second metal layer 72 is in direct contact with the second upper surface 83.

[0040] The first metallized film 31 and the second metallized film 32 are overlapped such that the first upper surface 81 side and the second lower surface 84 side face each other. As already described, the first metallized film 31 and the second metallized film 32 are in direct contact. Therefore, in the first embodiment, the first metal layer 71 included in the first metallized film 31 and the second lower surface 84 of the second dielectric film 42 included in the second metallized film 32 are in direct contact. And the first lower surface 82 of the first dielectric film 41 included in the first metallized film 31 and the second metal layer 72 included in the second metallized film 32 are in direct contact.

[0041] In the first embodiment, the capacitor body 1 includes a first end face electrode 21 disposed on one end face and a second end face electrode 22 disposed on the other end face. The first end face electrode 21 is disposed on the right side of the film capacitor 100. The second end face electrode 22 is disposed on the left side of the film capacitor 100.

[0042] The first metal layer 71 is connected to the first end face electrode 21. On the other hand, the second metal layer 72 is not connected to the first end face electrode 21. The material of the first end face electrode 21 is not particularly limited, and examples thereof include zinc (Zn), tin (Sn), or an alloy thereof. The thickness of the first end face electrode 21 is not particularly limited, and for example, it is 0.5 mm or more and 1.5 mm or less.

[0043] The second metal layer 72 is connected to the second end face electrode 22. On the other hand, the first metal layer 71 is not connected to the second end face electrode 22. The material and thickness of the second end face electrode 22 may be the same as or different from those of the first end face electrode 21. In the first embodiment, they are the same as the material and thickness of the first end face electrode 21.

[0044] Note that the thickness of the portion near the connection part of the first metal layer 71 with the first end face electrode 21 may be larger than the thickness of the portion other than the portion near the connection part of the first metal layer 71 with the first end face electrode 21. The thickness of the portion near the connection part of the second metal layer 72 with the second end face electrode 22 may be larger than the thickness of the portion other than the portion near the connection part of the second metal layer 72 with the second end face electrode 22.

[0045] Also, in the first embodiment, the first end face electrode 21 is connected to the negative electrode of the power source, and the second end face electrode 22 is connected to the positive electrode of the power source. That is, the first end face electrode 21 is the negative electrode, and the second end face electrode 22 is the positive electrode. In this case, it is easier to achieve an improvement in withstand voltage.

[0046] (1.2) Effects In the first embodiment, the film capacitor 100 can be charged by applying a voltage between the first end electrode 21 and the second end electrode 22. After charging, the film capacitor 100 can be discharged through the first end electrode 21 and the second end electrode 22. When using the film capacitor 100, dielectric breakdown of the first dielectric film 41 or the second dielectric film 42 may occur due to the movement of electrons from the first metal layer 71, which is electrically connected to the negative electrode, to the second metal layer 72, which is electrically connected to the positive electrode. However, the first metal layer 71, which is electrically connected to the negative electrode, is positioned between the first metal oxide layer 61 and the second dielectric film 42 so as to be in direct contact with the first metal oxide layer 61 and the second dielectric film 42. Therefore, the movement of electrons emitted from the first metal layer 71 toward the second metal layer 72 can be suppressed. This improves the dielectric strength of the film capacitor 100. As a result, dielectric breakdown of the first dielectric film 41 or the second dielectric film 42 can be suppressed.

[0047] In the first embodiment, a first metal oxide layer 61 is interposed between the first dielectric film 41 and the first metal layer 71 connected to the negative electrode. Therefore, even if the thickness of the first dielectric film 41 is reduced, the voltage withstand capability of the film capacitor 100 does not decrease easily. In other words, the first embodiment has the advantage of being able to increase the capacitance of the film capacitor 100 while improving the voltage withstand capability of the film capacitor 100.

[0048] (2) Second Embodiment (2.1) Film Capacitor The film capacitor 100 according to the second embodiment will be described with reference to Figure 2. Figure 2 shows the two metallized films 3 (first metallized film 31 and second metallized film 32) separated in order to make the following explanation easier to understand. That is, the first metallized film 31 and the second metallized film 32 are in direct contact. In the second embodiment, components similar to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and detailed explanations may be omitted.

[0049] Similar to the first embodiment, the film capacitor 100 according to the second embodiment comprises a capacitor body 1 formed by winding together a first metallized film 31 and a second metallized film 32, or by alternately stacking the first metallized film 31 and the second metallized film 32.

[0050] However, the second embodiment differs from the first embodiment in the arrangement of the first metal oxide layer 61 and the first metal layer 71, and in the relationship between the dielectric breakdown voltage of the first dielectric film 41 and the dielectric breakdown voltage of the second dielectric film 42. Specifically, in the second embodiment, the first metal layer 71 and the first metal oxide layer 61 are arranged on the first upper surface 81 of the first dielectric film 41, in order of proximity to the first upper surface 81. Furthermore, the dielectric breakdown voltage of the first dielectric film 41 is higher than the dielectric breakdown voltage of the second dielectric film 42.

[0051] Similar to the first embodiment, the first metallized film 31 has a constant width in the first direction D1, extends in the second direction D2, and has a constant thickness in the third direction D3. For example, the width of the first metallized film 31 may be the same as that of the first metallized film 31 in the first embodiment. The thickness range of the first metallized film 31 may be the same as that of the first metallized film 31 in the first embodiment, for example, 1.5 μm or more and 10.0 μm or less.

[0052] The first metallized film 31 includes a first dielectric film 41, a first metal oxide layer 61, and a first metal layer 71.

[0053] The first dielectric film 41 has a constant width in the first direction D1, extends in the second direction D2, and has thickness in the third direction D3.

[0054] The first dielectric film 41 has two main surfaces 8: a first upper surface 81 and a first lower surface 82 opposite to the first upper surface 81.

[0055] The thickness of the first dielectric film 41 is the distance between the first upper surface 81 and the first lower surface 82, and is not particularly limited, but for example, it is 1.0 μm or more and 10.0 μm or less. In this case, it is easier to improve the withstand voltage of the film capacitor 100.

[0056] The width and thickness of the first dielectric film 41 may be the same as, or different from, the width and thickness of the first dielectric film 41 according to the first embodiment. The first metal layer 71 and the first metal oxide layer 61 contained in the first metallized film 31 are formed by vapor deposition of metal or metal oxide, but the dielectric strength of the first dielectric film 41 may decrease due to the heat generated during vapor deposition. Therefore, from the viewpoint of maintaining the dielectric strength of the first dielectric film 41, it is preferable that the thickness of the first dielectric film 41 be moderately thick.

[0057] The first dielectric film 41 can be constructed using the materials listed as dielectrics constituting the first dielectric film 41 according to the first embodiment.

[0058] From the viewpoint of improving dielectric strength, it is preferable that the dielectric breakdown voltage of the first dielectric film 41 is increased.

[0059] Furthermore, from the viewpoint of improving dielectric strength, it is preferable that the dielectric breakdown potential gradient of the first dielectric film 41 is increased. For example, the dielectric breakdown potential gradient of the first dielectric film 41 is 500 V / m or more. In this case, improvement in dielectric strength becomes easier to achieve. This dielectric breakdown voltage is preferably 600 V / m or more, and more preferably 700 V / m or more.

[0060] The first metal oxide layer 61 may contain metal oxides that may be present in the first metal oxide layer 61 according to the first embodiment. Similar to the first embodiment, the first metal oxide layer 61 may contain Al ２ O ３ It is more preferable to include the following. In this case, it becomes easier to achieve improved dielectric strength. The thickness of the first metal oxide layer 61 may be the same as or different from the thickness of the first metal oxide layer 61 in the first embodiment.

[0061] The first metal layer 71 may contain metals that may be present in the first metal layer 71 according to the first embodiment. Similar to the first embodiment, it is preferable that the first metal layer 71 contains Al. In this case, it is easier to achieve improved dielectric strength. The thickness of the first metal layer 71 may be the same as or different from the thickness of the first metal layer 71 according to the first embodiment.

[0062] In the second embodiment, a first metal layer 71 and a first metal oxide layer 61 are arranged on the first upper surface 81 in order of proximity to the first upper surface 81. The first metal layer 71 is in direct contact with the first upper surface 81. The first metal oxide layer 61 is in direct contact with the first metal layer 71.

[0063] The second metallized film 32 has a constant width in the first direction D1, extends in the second direction D2, and has thickness in the third direction D3. For example, the width of the second metallized film 32 may be the same as that of the second metallized film 32 according to the first embodiment. The thickness range of the second metallized film 32 may be the same as that of the second metallized film 32 according to the first embodiment, for example, 1.5 μm or more and 10.0 μm or less. However, the thickness of the second metallized film 32 is different from the thickness of the first metallized film 31.

[0064] Similar to the first embodiment, the second metallized film 32 includes a second dielectric film 42 and a second metal layer 72.

[0065] The second dielectric film 42 has a constant width in the first direction D1, extends in the second direction D2, and has thickness in the third direction D3.

[0066] The second dielectric film 42 has two main surfaces 8: a second upper surface 83 and a second lower surface 84 opposite to the second upper surface 83.

[0067] The thickness of the second dielectric film 42 is the distance between the second upper surface 83 and the second lower surface 84, and is not particularly limited, but for example, it is 1.0 μm or more and 10.0 μm or less. In this case, it is easier to improve the withstand voltage of the film capacitor 100.

[0068] It is preferable that the thickness of the second dielectric film 42 and the thickness of the first dielectric film 41 satisfy a specific relationship. Specifically, in the second embodiment, the thickness of the first dielectric film 41 is greater than the thickness of the second dielectric film 42. In this case, it is easier to achieve an improvement in dielectric strength. The thickness of the first dielectric film 41 is preferably 1.05 times or more the thickness of the second dielectric film 42, more preferably 1.10 times or more, and even more preferably 1.20 times or more. In this case, it is easier to achieve an improvement in dielectric strength.

[0069] As already mentioned, the dielectric breakdown voltage of the dielectric film 4 in contact with the metal layer 7 electrically connected to the negative electrode is higher than the dielectric breakdown voltage of the dielectric film 4 not in contact with the metal layer 7 electrically connected to the negative electrode. Therefore, in the second embodiment, the dielectric breakdown voltage of the first dielectric film 41 is higher than the dielectric breakdown voltage of the second dielectric film 42. The dielectric breakdown voltage of the first dielectric film 41 is preferably 1.05 times or more, more preferably 1.10 times or more, and even more preferably 1.20 times or more than the dielectric breakdown voltage of the second dielectric film 42. In this case, it becomes easier to achieve improved dielectric strength.

[0070] Furthermore, it is preferable that the dielectric breakdown potential gradient of the second dielectric film 42 and the dielectric breakdown potential gradient of the first dielectric film 41 satisfy a specific relationship. Specifically, in the second embodiment, the dielectric breakdown potential gradient of the first dielectric film 41 is higher than the dielectric breakdown potential gradient of the second dielectric film 42. In this case, it becomes easier to achieve further improvement in dielectric strength. The dielectric breakdown potential gradient of the first dielectric film 41 is preferably 1.05 times or more, more preferably 1.10 times or more, and even more preferably 1.20 times or more, than the dielectric breakdown potential gradient of the second dielectric film 42. In this case, it becomes particularly easier to achieve improvement in dielectric strength.

[0071] The second metal layer 72 may contain metals that may be included in the second metal layer 72 according to the first embodiment. Similar to the first embodiment, it is preferable that the second metal layer 72 contains Al. In this case, it is easier to achieve improved dielectric strength. The thickness of the second metal layer 72 may be the same as or different from the thickness of the second metal layer 72 according to the first embodiment.

[0072] Similar to the first embodiment, a second metal layer 72 is arranged on the second upper surface 83. The second metal layer 72 is in direct contact with the second upper surface 83.

[0073] The first metallized film 31 and the second metallized film 32 are stacked so that their first upper surface 81 and second lower surface 84 face each other. As already mentioned, the first metallized film 31 and the second metallized film 32 are in direct contact. Therefore, in the second embodiment, the first metal oxide layer 61 contained in the first metallized film 31 and the second lower surface 84 of the second dielectric film 42 contained in the second metallized film 32 are in direct contact. Furthermore, the first lower surface 82 of the first dielectric film 41 contained in the first metallized film 31 and the second metal layer 72 contained in the second metallized film 32 are in direct contact.

[0074] In the second embodiment, similar to the first embodiment, the capacitor body 1 includes a first end-face electrode 21 arranged on one end face and a second end-face electrode 22 arranged on the other end face. The first end-face electrode 21 is located on the right side of the film capacitor 100. The second end-face electrode 22 is located on the left side of the film capacitor 100.

[0075] The first metal layer 71 is connected to the first end electrode 21. On the other hand, the second metal layer 72 is not connected to the first end electrode 21. The material of the first end electrode 21 is not particularly limited, but examples include zinc (Zn), tin (Sn), or alloys thereof. The thickness of the first end electrode 21 is not particularly limited, but for example, it is 0.5 mm or more and 1.5 mm or less.

[0076] The second metal layer 72 is connected to the second end electrode 22. On the other hand, the first metal layer 71 is not connected to the second end electrode 22. The material and thickness of the second end electrode 22 may be the same as or different from that of the first end electrode 21, but in the second embodiment, they are the same as those of the first end electrode 21.

[0077] Similar to the first embodiment, the thickness of the first metal layer 71 near the connection with the first end electrode 21 may be greater than the thickness of the first metal layer 71 in areas other than the connection with the first end electrode 21. The thickness of the second metal layer 72 near the connection with the second end electrode 22 may be greater than the thickness of the second metal layer 72 in areas other than the connection with the second end electrode 22.

[0078] Furthermore, in the second embodiment, the first end-face electrode 21 is connected to the negative terminal of the power supply, and the second end-face electrode 22 is connected to the positive terminal of the power supply. In other words, the first end-face electrode 21 is the negative terminal, and the second end-face electrode 22 is the positive terminal. In this case, it becomes easier to achieve improved voltage resistance.

[0079] (2.2) Effects The second embodiment also produces the same effects as the first embodiment. That is, the first metal layer 71, which is electrically connected to the negative electrode, is arranged between the first metal oxide layer 61 and the first dielectric film 41 so as to be in direct contact with the first metal oxide layer 61 and the first dielectric film 41. Therefore, the movement of electrons emitted from the first metal layer 71 toward the second metal layer 72 can be suppressed. This makes it possible to improve the dielectric strength of the film capacitor 100. As a result, dielectric breakdown of the first dielectric film 41 or the second dielectric film 42 can be suppressed.

[0080] (3) Summary As described above, the film capacitor 100 according to the embodiment can restrict the movement of electrons emitted from the metal layer 7 that is electrically connected to the negative electrode. Therefore, the voltage withstand capability of the film capacitor 100 can be improved.

[0081] The film capacitor 100 according to this embodiment can be manufactured by stacking two metallized films 3, but the metal oxide layer 6 is arranged on only one of the two metallized films 3. In other words, it is not necessary to arrange the metal oxide layer 6 on the other metallized film 3. Therefore, there is an advantage in that the manufacturing cost of the film capacitor 100 can be reduced.

[0082] This disclosure is not limited to the embodiments described above, and can be modified as appropriate within the scope of the claims and equivalents thereof. For example, the capacitor body 1 does not have to have an end electrode 2. Alternatively, if the capacitor body 1 has an end electrode 2, the first end electrode 21 may be connected to the positive terminal of the power supply, and the second end electrode 22 may be connected to the negative terminal of the power supply. In other words, the first end electrode 21 may be the positive terminal and the second end electrode 22 may be the negative terminal. The same effects and advantages as in the embodiments described above can be obtained in such embodiments as well.

[0083] 3. Aspects As will be clear from the above embodiments, this disclosure includes the following aspects. Hereafter, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0084] A film capacitor (100) according to a first aspect of the present disclosure comprises a capacitor body (1) formed by winding together a first metallized film (31) and a second metallized film (32) or by alternately stacking the first metallized film (31) and the second metallized film (32). The first metallized film (31) includes a first dielectric film (41), a first metal oxide layer (61), and a first metal layer (71). The first dielectric film (41) has a first upper surface (81) and a first lower surface (82) opposite to the first upper surface (81). On the first upper surface (81), the first metal oxide layer (61) and the first metal layer (71) are arranged in order from the first upper surface (81). The second metallized film (32) includes a second dielectric film (42) and a second metal layer (72). The second dielectric film (42) has a second upper surface (83) and a second lower surface (84) opposite to the second upper surface (83). A second metal layer (72) is disposed on the second upper surface (83). The first metallized film (31) and the second metallized film (32) are stacked so that the first upper surface (81) side and the second lower surface (84) side face each other. The dielectric breakdown voltage of the second dielectric film (42) is higher than that of the first dielectric film (41).

[0085] According to this embodiment, a film capacitor (100) that can achieve improved voltage resistance can be provided.

[0086] The film capacitor (100) according to the second aspect of the present disclosure includes a capacitor body (1) formed by overlapping and winding a first metallized film (31) and a second metallized film (32), or by alternately laminating the first metallized film (31) and the second metallized film (32). The first metallized film (31) includes a first dielectric film (41), a first metal oxide layer (61), and a first metal layer (71). The first dielectric film (41) has a first upper surface (81) and a first lower surface (82) opposite to the first upper surface (81). On the first upper surface (81), the first metal layer (71) and the first metal oxide layer (61) are arranged in order from the closest to the first upper surface (81). The second metallized film (32) includes a second dielectric film (42) and a second metal layer (72). The second dielectric film (42) has a second upper surface (83) and a second lower surface (84) opposite to the second upper surface (83). On the second upper surface (83), the second metal layer (72) is arranged. The first metallized film (31) and the second metallized film (32) are overlapped such that the first upper surface (81) side and the second lower surface (84) side face each other. The breakdown voltage of the first dielectric film (41) is higher than the breakdown voltage of the second dielectric film (42).

[0087] In the film capacitor (100) according to the third aspect of the present disclosure, in the first or second aspect, the first metal layer (71) and the second metal layer (72) contain Al. The first metal oxide layer (61) contains Al ２ O ３ and contains it.

[0088] In the film capacitor (100) according to the fourth aspect of the present disclosure, in any one of the first to third aspects, the capacitor body (1) includes a first end face electrode (21) arranged on one end face and a second end face electrode (22) arranged on the other end face. The first metal layer (71) is connected to the first end face electrode (21), and the second metal layer (72) is connected to the second end face electrode (22).

[0089] In the film capacitor (100) according to the fifth aspect of the present disclosure, in the fourth aspect, the first end face electrode (21) is a negative electrode, and the second end face electrode (22) is a positive electrode.

[0090] In the film capacitor (100) according to the sixth aspect of the present disclosure, in any one of the first and third to fifth aspects, the thickness of the second dielectric film (42) is greater than the thickness of the first dielectric film (41).

[0091] In the seventh aspect of the present disclosure, the film capacitor (100) is configured such that, in any one of the second to fifth aspects, the thickness of the first dielectric film (41) is greater than the thickness of the second dielectric film (42).

[0092] In the eighth aspect of the present disclosure, the film capacitor (100) is configured such that, in any one of the first and third to sixth aspects, the dielectric breakdown potential gradient of the second dielectric film (42) is greater than the dielectric breakdown potential gradient of the first dielectric film (41).

[0093] In the ninth aspect of the present disclosure, the film capacitor (100) is configured such that, in any one of the second to fifth and seventh aspects, the dielectric breakdown potential gradient of the first dielectric film (41) is greater than the dielectric breakdown potential gradient of the second dielectric film (42).

[0094] 1 Capacitor body 100 Film capacitor 2 End face electrodes 21 First end face electrode 22 Second end face electrode 3 Metallized film 31 First metallized film 32 Second metallized film 4 Dielectric film 41 First dielectric film 42 Second dielectric film 6 Metal oxide layer 61 First metal oxide layer 7 Metal layer 71 First metal layer 72 Second metal layer 81 First upper surface 82 First lower surface 83 Second upper surface 84 Second lower surface

Claims

1. The capacitor body comprises a first metallized film and a second metallized film superimposed and wound together, or a first metallized film and a second metallized film alternately laminated, wherein the first metallized film includes a first dielectric film, a first metal oxide layer, and a first metal layer, the first dielectric film has a first upper surface and a first lower surface opposite to the first upper surface, the first metal oxide layer and the first metal layer are arranged on the first upper surface in order from the first upper surface, the second metallized film includes a second dielectric film and a second metal layer, the second dielectric film has a second upper surface and a second lower surface opposite to the second upper surface, the second metal layer is arranged on the second upper surface, and the first metallized film and the second metallized film are superimposed so that the first upper surface side and the second lower surface side face each other. A film capacitor wherein the dielectric breakdown voltage of the second dielectric film is higher than the dielectric breakdown voltage of the first dielectric film.

2. The capacitor body comprises a first metallized film and a second metallized film superimposed and wound together, or a first metallized film and a second metallized film alternately laminated, wherein the first metallized film includes a first dielectric film, a first metal oxide layer, and a first metal layer, the first dielectric film has a first upper surface and a first lower surface opposite to the first upper surface, the first metal layer and the first metal oxide layer are arranged on the first upper surface in order from the first upper surface, the second metallized film includes a second dielectric film and a second metal layer, the second dielectric film has a second upper surface and a second lower surface opposite to the second upper surface, the second metal layer is arranged on the second upper surface, and the first metallized film and the second metallized film are superimposed so that the first upper surface side and the second lower surface side face each other. A film capacitor in which the dielectric breakdown voltage of the first dielectric film is higher than the dielectric breakdown voltage of the second dielectric film.

3. The first metal layer and the second metal layer contain Al, and the first metal oxide layer contains Al ２ O ３ A film capacitor according to claim 1 or 2, comprising the above.

4. The film capacitor according to any one of claims 1 to 3, wherein the capacitor body comprises a first end-face electrode disposed on one end face and a second end-face electrode disposed on the other end face, the first metal layer is connected to the first end-face electrode and the second metal layer is connected to the second end-face electrode.

5. The film capacitor according to claim 4, wherein the first end electrode is a negative electrode and the second end electrode is a positive electrode.

6. The film capacitor according to any one of claims 1 and 3 to 5, wherein the thickness of the second dielectric film is greater than the thickness of the first dielectric film.

7. The film capacitor according to any one of claims 2 to 5, wherein the thickness of the first dielectric film is greater than the thickness of the second dielectric film.

8. The film capacitor according to any one of claims 1 and 3 to 6, wherein the dielectric breakdown potential gradient of the second dielectric film is greater than the dielectric breakdown potential gradient of the first dielectric film.

9. The film capacitor according to any one of claims 2 to 5 and 7, wherein the dielectric breakdown potential gradient of the first dielectric film is greater than the dielectric breakdown potential gradient of the second dielectric film.

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