Film capacitor and metallized film

Abstract

This film capacitor includes a capacitor main body, a first end surface electrode, and a second end surface electrode. A first metallized film has a first dielectric film and a first electrode. The first electrode is obtained by stacking a first aluminum oxide layer and a first metal layer. A second metallized film has a second dielectric film and a second electrode. The second electrode is obtained by stacking a second aluminum oxide layer and a second metal layer. The element ratio of O to Al in each of the first aluminum oxide layer and the second aluminum oxide layer as determined by composition analysis by means of X-ray photoelectron spectroscopy is 1.3 or more and 1.5 or less.

Description

Film capacitors and metallized films

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to film capacitors and metallized films, and more particularly to film capacitors and metallized films that utilize the film as a dielectric.

[0002] Patent Document 1 discloses a metallized film capacitor. This metallized film capacitor comprises a pair of metallized films, each having a dielectric film and a vapor-deposited metal electrode formed thereon, which are wound or laminated together so that the vapor-deposited metal electrodes formed on the pair of metallized films face each other via the dielectric film, and a pair of metallikon electrodes formed on both end surfaces of the element. At least one of the vapor-deposited metal electrodes of the pair of metallized films is primarily composed of aluminum and has an oxide layer formed on the bonding surface with the dielectric film and a magnesium-containing layer formed on the oxide layer, with the atomic concentration ratio of magnesium being greatest in the magnesium-containing layer.

[0003] The technology of Patent Document 1 is said to be capable of improving the withstand voltage of a metallized film capacitor.

[0004] JP 2013-65747 A

[0005] A film capacitor according to one aspect of the present disclosure includes a capacitor body including a first metallized film and a second metallized film, a first end electrode disposed on one end surface of the capacitor body, and a second end electrode disposed on the other end surface of the capacitor body. The first metallized film and the second metallized film are wound or alternately stacked. The first metallized film includes a first dielectric film and a first electrode connected to the first end electrode. The first dielectric film has a first surface on which the first electrode is disposed and a second surface opposite the first surface. The first electrode includes a first aluminum oxide layer and a first metal layer, and the first aluminum oxide layer and the first metal layer are stacked in this order from the first surface. The second metallized film includes a second dielectric film and a second electrode connected to the second end electrode. The second dielectric film has a third surface on which the second electrode is disposed and a fourth surface opposite the third surface. The second electrode includes a second aluminum oxide layer and a second metal layer, and the second aluminum oxide layer and the second metal layer are stacked in this order from the third surface. The second surface of the first dielectric film faces the third surface of the second dielectric film. The element ratio of O to Al in composition analysis by X-ray photoelectron spectroscopy of each of the first aluminum oxide layer and the second aluminum oxide layer is 1.3 or more and 1.5 or less.

[0006] A metallized film according to one aspect of the present disclosure includes a long dielectric film and an electrode disposed on one surface of the dielectric film. The electrode includes an aluminum oxide layer and a metal layer, and the aluminum oxide layer and the metal layer are stacked in this order from the one surface. Composition analysis of the aluminum oxide layer by X-ray photoelectron spectroscopy reveals that the elemental ratio of O to Al is 1.3 or more and 1.5 or less.

[0007] According to the present disclosure, it is possible to provide a film capacitor and a metallized film that have excellent insulation properties at high temperatures.

[0008] FIG. 1 is a schematic partial cross-sectional view showing a film capacitor according to an embodiment of the present disclosure.

[0009] Recently, there has been a growing demand for film capacitors with higher performance, and there is a demand for improved insulation properties at higher temperatures, for example, at 125°C.

[0010] The present disclosure provides a film capacitor and a metallized film that have excellent insulation properties at high temperatures.

[0011] 1. Overview The film capacitor 100 of the present disclosure will be described below with reference to FIG. 1 . FIG. 1 is a schematic diagram, and the size and thickness ratios of the components in FIG. 1 do not necessarily reflect the actual dimensional ratios. Furthermore, the arrows indicating the directions in FIG. 1 are not intended to define the directions in which the film capacitor 100 is used; they are merely shown to facilitate understanding of the description and have no substance. The first direction D1, the second direction D2 (not shown), and the third direction D3 are mutually orthogonal. The first direction D1 is the short-side direction (width direction) of the dielectric film 4 and may also be referred to as the "left-right direction." The second direction D2 is the longitudinal direction of the dielectric film and may also be referred to as the "front-rear direction." The third direction D3 is the thickness direction of the dielectric film and may also be referred to as the "up-down direction."

[0012] The film capacitor 100 of the present disclosure includes a capacitor body 1 formed by stacking two metallized films 3, and two end electrodes 2 formed on each of both end surfaces of the capacitor body 1. The metallized film 3 includes a dielectric film 4 and an electrode 5. Each of the electrodes 5 of the two metallized films 3 is connected to a different end electrode 2. The electrode 5 includes an aluminum oxide layer 6 and a metal layer 7, and the aluminum oxide layer 6 and the metal layer 7 are stacked in descending order from the surface 8 of the dielectric film 4 on which the electrode 5 is disposed. In the film capacitor 100 of the present disclosure, the elemental ratio of O to Al (hereinafter also referred to as the O / Al elemental ratio) of the aluminum oxide layer 6 is 1.3 or more and 1.5 or less in composition analysis by X-ray photoelectron spectroscopy.

[0013] The film capacitor 100 of the present disclosure has excellent insulating properties at high temperatures by selecting an aluminum oxide layer 6 as the metal oxide layer and by setting the O / Al element ratio of the aluminum oxide layer 6 within the above-mentioned specific range. That is, as shown in the examples described later, the effect of improving the breakdown voltage (BDV) at 125°C is significant. The present disclosure has found a range of the O / Al element ratio of the aluminum oxide layer 6 that exhibits the same but significantly superior effects as those of prior art such as Patent Document 1.

[0014] 2. Details (1) Film Capacitor The film capacitor 100 according to this embodiment will be described. Examples of the film capacitor 100 include a wound film capacitor 100 and a stacked film capacitor 100.

[0015] 1 is a diagram showing a portion of a cross section of a film capacitor 100. The film capacitor 100 includes a capacitor body 1 and end electrodes 2 (a first end electrode 21 and a second end electrode 22).

[0016] <Capacitor Body> Capacitor body 1 includes a first metallized film 31 and a second metallized film 32. In wound film capacitor 100, capacitor body 1 includes first metallized film 31 and second metallized film 32 that are stacked and wound. In laminated film capacitor 100, capacitor body 1 includes first metallized film 31 and second metallized film 32 that are alternately stacked.

[0017] <Metalized Film> The first metalized film 31 and the second metalized film 32 each have a certain width in the first direction D1, extend in the second direction D2, and have a thickness in the third direction D3. The widths and thicknesses of the first metalized film 31 and the second metalized film 32 may be the same or different, but in this embodiment, the widths and thicknesses of the first metalized film 31 and the second metalized film 32 are approximately equal.

[0018] First metallized film 31 includes a first dielectric film 41 and a first electrode 51. Second metallized film 32 includes a second dielectric film 42 and a second electrode 52.

[0019] (Dielectric Film) The dielectric film 4 (first dielectric film 41 and second dielectric film 42) is a film made of a dielectric material.

[0020] The first dielectric film 41 and the second dielectric film 42 each have a constant width in the first direction D1, extend in the second direction D2, and have a constant thickness in the third direction D3.

[0021] For example, long dielectric films are used as the first dielectric film 41 and the second dielectric film 42 in the case of the wound film capacitor 100, and for example, dielectric films that are rectangular in plan view are used in the case of the laminated film capacitor 100. The length of the long dielectric film is, for example, 1 m or more and 800 m or less, and the width is, for example, 5 mm or more and 100 mm or less. The length of one side of the rectangular dielectric film in plan view is, for example, 5 mm or more and 100 mm or less.

[0022] The dielectric includes at least one material selected from the group consisting of, for example, polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polycarbonate (PC), and polystyrene (PS). These materials may be stretched, for example, by biaxial stretching. The dielectric constituting the first dielectric film 41 and the dielectric constituting the second dielectric film 42 may be the same or different, but in this embodiment, the same dielectric is used.

[0023] The first dielectric film 41 has a first surface 81 and a second surface 82. The first surface 81 is the upper surface. The second surface 82 is the surface opposite to the first surface 81. In other words, the second surface 82 is the lower surface. The second dielectric film 42 has a third surface 83 and a fourth surface 84. The third surface 83 is the upper surface. The fourth surface 84 is the surface opposite to the third surface 83. In other words, the fourth surface 84 is the lower surface.

[0024] The thickness of the first dielectric film 41 is the distance between the first surface 81 and the second surface 82, and the thickness of the second dielectric film 42 is the distance between the third surface 83 and the fourth surface 84. The thicknesses of the first dielectric film 41 and the second dielectric film 42 are not particularly limited, but are, for example, 1.0 μm or more and 10.0 μm or less. The length, width, and thickness of the first dielectric film 41 and the second dielectric film 42 may be the same or different, but are approximately equal in this embodiment.

[0025] The second surface 82 faces the second metallized film 32. More specifically, the second surface 82 of the first dielectric film 41 faces the third surface 83 of the second dielectric film 42. The fourth surface 84 faces the first metallized film 31. More specifically, the fourth surface 84 of the second dielectric film 42 faces the first surface 81 of the first dielectric film 41. In this way, in the film capacitor 100, the second surface 82 side of the first metallized film 31 faces the third surface 83 side of the second metallized film 32.

[0026] The fourth surface 84 and the first electrode 51 may be separated from each other in the vertical direction or may be in contact with each other, but in this embodiment, the fourth surface 84 and the first electrode 51 are separated from each other. The second surface 82 and the second electrode 52 may be separated from each other in the vertical direction or may be in contact with each other, but in this embodiment, the second surface 82 and the second electrode 52 are separated from each other.

[0027] (Electrodes) The first electrode 51 is disposed on the first surface 81 of the first dielectric film 41. The second electrode 52 is disposed on the third surface 83 of the second dielectric film 42. The first electrode 51 and the second electrode 52 may be disposed over the entire first surface 81 or the entire third surface 83, or may be disposed over a part of the first surface 81 or a part of the third surface 83.

[0028] The first electrode 51 includes a first aluminum oxide layer 61 and a first metal layer 71. The first aluminum oxide layer 61 and the first metal layer 71 are stacked in order from the bottom to the top in the third direction D3. In other words, the first dielectric film 41, the first aluminum oxide layer 61, and the first metal layer 71 are stacked in order from the bottom to the top in the third direction D3. The second electrode 52 includes a second aluminum oxide layer 62 and a second metal layer 72. The second aluminum oxide layer 62 and the second metal layer 72 are stacked in order from the bottom to the top in the third direction D3. In other words, the second dielectric film 42, the second aluminum oxide layer 62, and the second metal layer 72 are stacked in order from the bottom to the top in the third direction D3.

[0029] [Aluminum Oxide Layer] The aluminum oxide layer 6 (first aluminum oxide layer 61 and second aluminum oxide layer 62) contains an oxide of aluminum (Al). The oxide of aluminum (Al) can be represented by the chemical formula AlOx (x is a number greater than 0 and equal to or less than 1.5), for example.

[0030] The thickness of the first aluminum oxide layer 61 and the second aluminum oxide layer 62 is not particularly limited, but is, for example, 3 nm or more and 50 nm or less.

[0031] The element ratio of O to Al (O / Al element ratio) in the first aluminum oxide layer 61 and the second aluminum oxide layer 62, as determined by composition analysis using X-ray photoelectron spectroscopy, is 1.3 or more and 1.5 or less. By setting the O / Al element ratio of the aluminum oxide layer 6 within this range, the film capacitor 100 has excellent insulation properties at high temperatures. The "O / Al element ratio" is determined by performing composition analysis using X-ray photoelectron spectroscopy, and determining the ratio of Al to Al from the peaks of aluminum (Al) and oxygen (O) measured. ２ O ３ It can be determined by determining the number of Al and O atoms using a standard sample such as a single crystal, and then calculating the ratio of the number of Al and O atoms.

[0032] The lower limit of the O / Al element ratio is preferably 1.33 or more, more preferably 1.35 or more, even more preferably 1.37 or more, and particularly preferably 1.38 or more. In this case, the insulating properties at high temperatures can be further improved. The upper limit of the O / Al element ratio may be 1.47 or less, 1.45 or less, 1.43 or less, or 1.41 or less. In this case, the aluminum oxide layer 6 can be formed more easily, and the insulating properties at high temperatures can be further improved.

[0033] The aluminum oxide layer 6 (first aluminum oxide layer 61 and second aluminum oxide layer 62) can be formed, for example, by vapor deposition on one surface 8 (first surface 81 or third surface 83) of the dielectric film 4 (first dielectric film 41 and second dielectric film 42). Specifically, the aluminum oxide layer 6 can be formed, for example, by vapor deposition of metallic aluminum in the presence of oxygen gas.

[0034] [Metal Layer] The metal layer 7 (first metal layer 71 and second metal layer 72) contains at least one metal 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), titanium (Ti), etc. The thickness of the first metal layer 71 and the second metal layer 72 is not particularly limited, but is, for example, 3 nm or more and 100 nm or less.

[0035] In this embodiment, the first metal layer 71 and the second metal layer 72 are disposed so as to be in direct contact with the first aluminum oxide layer 61 or the second aluminum oxide layer 62, respectively. The first metal layer 71 and the second metal layer 72 may be disposed so as to cover the entire surface of the first aluminum oxide layer 61 or the second aluminum oxide layer 62, respectively, or may be disposed so as to cover a portion of the surface of the first aluminum oxide layer 61 or the second aluminum oxide layer 62.

[0036] The first metal layer 71 and the second metal layer 72 may each be solid or divided into multiple regions. The first metal layer 71 and the second metal layer 72 may each have a fuse. The fuse melts when an excessive current flows, thereby interrupting the circuit.

[0037] The metal layer 7 (first metal layer 71 and second metal layer 72) can be formed by vapor deposition, for example, on the surface of the aluminum oxide layer 6 (first aluminum oxide layer 61 or second aluminum oxide layer 62) opposite to the dielectric film 4 (first dielectric film 41 or second dielectric film 42). Specifically, the metal layer 7 can be formed by vapor deposition of the above-mentioned metal, for example.

[0038] <End Surface Electrodes> The first end surface electrode 21 is disposed on the right side of the film capacitor 100 and is connected to the first electrode 51. The second end surface electrode 22 is disposed on the left side of the film capacitor 100 and is connected to the second electrode 52.

[0039] The material of the first end surface electrode 21 and the second end surface electrode 22 is not particularly limited, but examples thereof include zinc (Zn), tin (Sn), and alloys thereof. The first end surface electrode 21 and the second end surface electrode 22 can be formed, for example, by thermally spraying these metals onto both end surfaces of the capacitor body 1. The thickness of the first end surface electrode 21 and the second end surface electrode is not particularly limited, but is, for example, 0.5 mm to 1.5 mm.

[0040] (2) Method for Manufacturing the Film Capacitor A method for manufacturing the film capacitor 100 according to this embodiment will be described.

[0041] The manufacturing method of the film capacitor 100 includes, for example, a dielectric film preparation step, a vapor deposition step, a lamination step, and an end surface electrode formation step. The vapor deposition step includes a first vapor deposition step and a second vapor deposition step. Each step will be described below.

[0042] (Dielectric Film Preparation Step) In the dielectric film preparation step, a dielectric film 4 is prepared. To manufacture the wound film capacitor 100, a long dielectric film 4 is prepared. To manufacture the stacked film capacitor 100, a dielectric film 4 having a rectangular shape in plan view or the like is prepared.

[0043] (First Vapor Deposition Step) In the first vapor deposition step, the aluminum oxide layer 6 is formed by vapor deposition. Specifically, for example, metallic aluminum is evaporated onto one surface 8 of the dielectric film 4 using a vacuum vapor deposition apparatus, and oxygen gas is introduced therein to vapor-deposit aluminum oxide represented by the chemical formula AlOx (x is a number between 1.3 and 1.5), thereby forming the aluminum oxide layer 6. The value of x in AlOx can be adjusted by controlling the vapor deposition conditions, such as the amount of oxygen gas supplied.

[0044] (Second Vapor Deposition Step) In the second vapor deposition step, a metal layer 7 is formed on the surface of the aluminum oxide layer 6 formed in the first vapor deposition step, opposite the dielectric film 4, by vapor deposition of a metal using, for example, a vacuum vapor deposition apparatus, thereby obtaining a metallized film 3.

[0045] (Lamination Process) In the lamination process, the multiple metallized films 3 obtained in the second vapor deposition process are laminated. To obtain a wound type film capacitor 100, the multiple metallized films 3 are stacked and wound. To obtain a laminated type film capacitor 100, the multiple metallized films 3 are alternately laminated. In this way, the capacitor body 1 is obtained.

[0046] (End Surface Electrode Forming Step) In the end surface electrode forming step, end surface electrodes 2 are formed by metal spraying or the like on both end surfaces of the capacitor body 1 obtained in the lamination step.

[0047] In this manner, the film capacitor 100 can be manufactured.

[0048] 3. Aspects As is clear from the above embodiments, the present disclosure includes the following aspects. In the following, reference numerals are given in parentheses only to clarify the correspondence with the embodiments.

[0049] A film capacitor (100) according to a first aspect of the present invention comprises a capacitor body (1) including a first metallized film (31) and a second metallized film (32), a first end electrode (21) disposed on one end surface of the capacitor body (1), and a second end electrode (22) disposed on the other end surface of the capacitor body (1). The first metallized film (31) and the second metallized film (32) are wound in a stacked manner or alternately laminated. The first metallized film (31) has a first dielectric film (41) and a first electrode (51) connected to the first end electrode (21). The first dielectric film (41) has a first surface (81) on which the first electrode (51) is disposed and a second surface (82) opposite the first surface (81). The first electrode (51) includes a first aluminum oxide layer (61) and a first metal layer (71), and the first aluminum oxide layer (61) and the first metal layer (71) are laminated in this order from the first surface (81). The second metallized film (32) includes a second dielectric film (42) and a second electrode (52) connected to the second end surface electrode (22). The second dielectric film (42) has a third surface (83) on which the second electrode (52) is disposed, and a fourth surface (84) opposite the third surface. The second electrode (52) includes a second aluminum oxide layer (62) and a second metal layer (72), and the second aluminum oxide layer (62) and the second metal layer (72) are laminated in this order from the third surface (83). The second surface (82) of the first dielectric film (41) faces the third surface (83) of the second dielectric film (42). The element ratio of O to Al in composition analysis by X-ray photoelectron spectroscopy of each of the first aluminum oxide layer (61) and the second aluminum oxide layer (62) is 1.3 or more and 1.5 or less.

[0050] According to this aspect, by setting the O / Al element ratio of the first aluminum oxide layer (61) and the second aluminum oxide layer (62) within the above-mentioned specific range, the film capacitor (100) can have excellent insulating properties at high temperatures.

[0051] A metallized film (3) according to a second aspect includes a long dielectric film (4) and an electrode (5) disposed on one surface (8) of the dielectric film (4). The electrode (5) includes an aluminum oxide layer (6) and a metal layer (7), and the aluminum oxide layer (6) and the metal layer (7) are laminated in this order from the one surface (8). The aluminum oxide layer (6) has an elemental ratio of O to Al of 1.3 or more and 1.5 or less in composition analysis by X-ray photoelectron spectroscopy.

[0052] According to this aspect, by setting the O / Al element ratio of the aluminum oxide layer (6) in the metallized film (3) within the above-mentioned specific range, the film capacitor (100) using the metallized film (3) can have excellent insulating properties at high temperatures.

[0053] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0054] (1) Preparation of a film capacitor An aluminum oxide layer was formed by vapor deposition on one side of a dielectric film (material: biaxially oriented polypropylene, length 30 m, width 30 mm, thickness 2.5 μm), and then a metal layer was formed by vapor deposition of aluminum (Al) on the surface of the aluminum oxide layer to prepare a metallized film. The thickness of the aluminum oxide layer was 15 nm, and the thickness of the metal layer was 20 nm.

[0055] Next, two of the metallized films prepared above were wound together to prepare a capacitor body, and then Zn was sprayed onto both end surfaces of the prepared capacitor body to form end surface electrodes. After that, the capacitor body was pressed and baked at 120°C for 12 hours to prepare a film capacitor.

[0056] (2) Evaluation (Composition Analysis of Aluminum Oxide Layer) The composition of the aluminum oxide layer was analyzed by X-ray photoelectron spectroscopy (XPS) to measure the content ratio of each element (aluminum (Al) and oxygen (O)) (O / Al element ratio).

[0057] The measurement conditions for the XPS method are shown below.

[0058] Apparatus: QUANTES (manufactured by ULVAC-PHI, Inc.) Excitation X-ray: monochromatic AlKα X-ray output: 25 W X-ray diameter: 100 μm Photoelectron escape angle: 15° Ion gun used: Ar ion gun (2 kV, 7 mA) Standard sample: Al ２ O ３ In order to measure the O / Al element ratio of the single crystal aluminum oxide layer, the outermost metal layer of the electrode was removed by sputtering using an Ar ion gun, and then the O / Al element ratio was measured at multiple locations (for example, 10 arbitrary locations) on the surface of the aluminum oxide layer, and the arithmetic mean value (Ri) of the O / Al element ratio was calculated. ２ O ３ The O / Al element ratio (Rs) of the aluminum oxide layer (single crystal) was also measured in the same manner, and a correction coefficient (k) was calculated using the following formula (1) so that this value would be 1.5. The thus-calculated correction coefficient k was used to correct the measured O / Al element ratio (Ri), and the resulting value was defined as the "O / Al element ratio of the aluminum oxide layer (the element ratio of O to Al in composition analysis by X-ray photoelectron spectroscopy)" (R). That is, R was calculated using the following formula (2).

[0059] k=1.5÷Rs (1) R=k×Ri (2) (Evaluation of 125° C. Breakdown Voltage (BDV) Improvement Effect) The film capacitor prepared above was left in an environment of 125° C. for 3 hours.

[0060] After the standing, a film sample was prepared from the film capacitor, and a sheet withstand voltage test was performed on each sample.

[0061] In the sheet withstand voltage test, the forward voltage was increased from 0 V at a rate of 100 V per second, and the withstand voltage was defined as the voltage at which the leakage current of the film became 10 mA. The arithmetic mean value of the measured values ​​of N samples (N=30) was taken as the withstand voltage (P) of each sample.

[0062] Also, a film capacitor without an aluminum oxide layer was prepared and left to stand for 3 hours in an environment of 125° C., and then the withstand voltage (Q) of this film capacitor was measured in the same manner.

[0063] The 125°C BDV improvement effect was calculated by the following formula.

[0064] 125°C BDV improvement effect (%) = Withstand voltage (P) of each sample × 100 / Withstand voltage (Q) Film capacitors with different aluminum oxide layer compositions (O / Al element ratios) were fabricated, and the 125°C BDV improvement effect of each film capacitor was measured. The evaluation results are shown in Table 1 below.

[0065]

[0066] As is clear from the results in Table 1 above, the film capacitor according to this embodiment has a large effect of improving the 125° C. BDV and is excellent in insulation at high temperatures.

[0067] REFERENCE SIGNS LIST 100 Film capacitor 1 Capacitor body 2 End electrode 21 First end electrode 22 Second end electrode 3 Metallized film 31 First metallized film 32 Second metallized film 4 Dielectric film 41 First dielectric film 42 Second dielectric film 5 Electrode 51 First electrode 52 Second electrode 6 Aluminum oxide layer 61 First aluminum oxide layer 62 Second aluminum oxide layer 7 Metal layer 71 First metal layer 72 Second metal layer 8 Surface 81 First surface 82 Second surface 83 Third surface 84 Fourth surface

Claims

1. A capacitor body including a first metallized film and a second metallized film; a first edge electrode disposed on one edge of the capacitor body; and a second edge electrode disposed on the other edge of the capacitor body, wherein the first metallized film and the second metallized film are overlapping and wound or alternately laminated; the first metallized film has a first dielectric film and a first electrode connected to the first edge electrode; the first dielectric film has a first side on which the first electrode is disposed and a second side opposite the first side; the first electrode includes a first aluminum oxide layer and a first metal layer, and the first aluminum oxide layer and the first metal layer are laminated in this order from the first side; the second metallized film has a second dielectric film and a second electrode connected to the second edge electrode; and the second dielectric film has a third side on which the second electrode is disposed and a fourth side opposite the third side. the second electrode includes a second aluminum oxide layer and a second metal layer, and the second aluminum oxide layer and the second metal layer are stacked in this order from the third surface; the second surface of the first dielectric film faces the third surface of the second dielectric film; and the elemental ratio of O to Al in composition analysis by X-ray photoelectron spectroscopy of each of the first aluminum oxide layer and the second aluminum oxide layer is 1.3 or more and 1.5 or less.

2. A metallized film comprising a long dielectric film and an electrode disposed on one side of said dielectric film, said electrode including an aluminum oxide layer and a metal layer, said aluminum oxide layer and metal layer being laminated in this order from said one side, and wherein the elemental ratio of O to Al in composition analysis by X-ray photoelectron spectroscopy of said aluminum oxide layer is 1.3 or more and 1.5 or less.

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