Capacitor

Abstract

A capacitor 1 comprises: a capacitor element 10 including an element body 11 and an external electrode 12a (12b) provided on an end surface of the element body 11; a lead-out terminal 20a (20b) electrically connected to the external electrode 12a (12b); a metal case 30 inside of which the capacitor element 10 is accommodated so that the lead-out terminal 20a (20b) protrudes toward the exterior; an insulating member 40 that is accommodated in the interior of the metal case 30 and positions the capacitor element 10 so that the lead-out terminal 20a (20b) and the metal case 30 are not in contact; and a filler resin 50 with which the interior of the metal case 30 is filled so as to embed the capacitor element 10. A protrusion 35 protruding toward the capacitor element 10 is provided to the inner surface of the metal case 30 at a position at which the insulating member 40 is not present, and the shortest distance between the capacitor element 10 and the protrusion 35 is smaller than the shortest distance between the lead-out terminal 20a (20b) and the metal case 30.

Description

capacitor

[0001] The present invention relates to a capacitor.

[0002] Patent Document 1 discloses a case-molded capacitor in which a bus bar provided with electrode terminals for external connection is connected to the electrode portion of a capacitor element, and the capacitor element is housed in a case with an opening on the top surface and molded with resin except for at least the electrode terminals of the bus bar, wherein the case is a metal case and an insulating heat transfer layer is provided between the bottom surface of the metal case and the capacitor element.

[0003] WO 2008 / 108089

[0004] In a case-molded capacitor, heat generation from the capacitor element may cause a deterioration in electrical characteristics. Therefore, if a metal case is used to house the capacitor element in a case-molded capacitor, the heat generated in the capacitor element is diffused into the metal case, which is expected to facilitate cooling of the capacitor element. However, in a case-molded capacitor using a metal case, unless electrical insulation is ensured between the capacitor element (particularly the electrodes) and the metal case, electrical conduction between the capacitor element and the metal case may occur, impairing the capacitor's functionality.

[0005] In contrast, the case molded capacitor described in Patent Document 1 provides an insulating heat transfer layer between the bottom surface of the metal case and the capacitor element, thereby ensuring electrical insulation between the capacitor element and the metal case and allowing heat generated in the capacitor element to be diffused and removed through the insulating heat transfer layer into the metal case. However, as shown in Figure 2 and other figures of Patent Document 1, the case molded capacitor described in Patent Document 1 requires a molding resin for molding the capacitor element and the insulating heat transfer layer in addition to the insulating heat transfer layer, which results in a complex structure.

[0006] The present invention has been made to solve the above problems, and aims to provide a capacitor that has a simple structure that can ensure electrical insulation between the capacitor element and the metal case while also improving the cooling function of the capacitor element.

[0007] The capacitor of the present invention comprises a capacitor element having a base body and an external electrode provided on an end face of the base body, a lead terminal electrically connected to the external electrode, a metal case in which the capacitor element is housed so that the lead terminal protrudes outward, an insulating member housed inside the metal case and positions the capacitor element so that the lead terminal does not come into contact with the metal case, and a filling resin filled inside the metal case so as to embed the capacitor element, wherein the inner surface of the metal case is provided with a protrusion protruding toward the capacitor element at a position where the insulating member is not present, and the shortest distance between the capacitor element and the protrusion is shorter than the shortest distance between the lead terminal and the metal case.

[0008] According to the present invention, it is possible to provide a capacitor that can ensure electrical insulation between the capacitor element and the metal case and improve the cooling function of the capacitor element with a simple structure.

[0009] Fig. 1 is a schematic perspective view showing an example of a capacitor of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a cross section of the capacitor shown in Fig. 1 taken along line segment a1-a2. Fig. 3 is a schematic cross-sectional view showing an example of a cross section of the capacitor shown in Fig. 1 taken along line segment b1-b2. Fig. 4 is a schematic perspective view showing an example of the capacitor element shown in Figs. 1, 2, and 3. Fig. 5 is a schematic cross-sectional view showing an example of a cross section of the capacitor element shown in Fig. 4 taken along line segment c1-c2.

[0010] The capacitor of the present invention will be described below. Note that the present invention is not limited to the following configurations and may be modified as appropriate within the scope of the present invention. In addition, a combination of multiple individual preferred configurations described below also constitutes the present invention.

[0011] Although a film capacitor will be described below as an example of the capacitor of the present invention, the capacitor of the present invention can also be applied to capacitors other than film capacitors.

[0012] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, scale, etc. may differ from those of the actual product.

[0013] In this specification, terms indicating the relationship between elements (e.g., "parallel," "orthogonal," etc.) and terms indicating the shape of elements not only mean the literal strict form, but also mean a range that is substantially equivalent, for example, a range that includes a difference of about a few percent.

[0014] The capacitor of the present invention comprises a capacitor element having a base body and an external electrode provided on an end face of the base body, a lead terminal electrically connected to the external electrode, a metal case in which the capacitor element is housed so that the lead terminal protrudes outward, an insulating member housed inside the metal case and positions the capacitor element so that the lead terminal does not come into contact with the metal case, and a filling resin filled inside the metal case so as to embed the capacitor element, wherein the inner surface of the metal case is provided with a protrusion protruding toward the capacitor element at a position where the insulating member is not present, and the shortest distance between the capacitor element and the protrusion is shorter than the shortest distance between the lead terminal and the metal case.

[0015] Fig. 1 is a schematic perspective view showing an example of a capacitor of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a cross section of the capacitor shown in Fig. 1 taken along line a1-a2. Fig. 3 is a schematic cross-sectional view showing an example of a cross section of the capacitor shown in Fig. 1 taken along line b1-b2.

[0016] The capacitor 1 shown in Figures 1, 2, and 3 has a capacitor element 10 (see Figure 4 described later), a first lead terminal 20a, a second lead terminal 20b, a metal case 30, an insulating member 40, and a filling resin 50.

[0017] In FIG. 1 and other figures, the first direction D1, the second direction D2, and the third direction D3 are perpendicular to one another.

[0018] Fig. 4 is a schematic perspective view showing an example of the capacitor element shown in Fig. 1, Fig. 2, and Fig. 3. Fig. 5 is a schematic cross-sectional view showing an example of a cross section of the capacitor element shown in Fig. 4 taken along line c1-c2.

[0019] The capacitor element 10 shown in FIGS. 4 and 5 has an element body 11, a first external electrode 12a, and a second external electrode 12b.

[0020] Body 11 is a wound body in which first metallized film 13 a and second metallized film 13 b are wound in a stacked state in first direction D1. That is, capacitor 1, more specifically capacitor element 10, is a wound-type film capacitor in which metallized films are wound in a stacked state.

[0021] Capacitor 1, more specifically capacitor element 10, may be a laminated film capacitor in which metallized films are laminated.

[0022] From the viewpoint of reducing the height of capacitor element 10, it is preferable that element body 11 has a flat cross-sectional shape when viewed in a cross section perpendicular to the winding axis direction (second direction D2 in FIG. 4 ) of element body 11. More specifically, it is preferable that element body 11 be pressed into a flat shape such as an ellipse or oval, and that the cross-sectional shape of element body 11 be a shape that is thinner than when the cross-sectional shape of element body 11 is a perfect circle.

[0023] Whether or not the element body has been pressed to have a flat cross-sectional shape can be confirmed, for example, by checking whether or not there are press marks on the element body.

[0024] Capacitor element 10 may have a cylindrical winding shaft that is disposed on the central axis of first metallized film 13 a and second metallized film 13 b in a wound state and serves as the winding shaft when winding first metallized film 13 a and second metallized film 13 b.

[0025] First metallized film 13a includes first dielectric film 14a and first metal layer 15a.

[0026] The first dielectric film 14a has a first main surface 14aa and a second main surface 14ab facing each other in the first direction D1.

[0027] The first metal layer 15a is provided on the first main surface 14aa of the first dielectric film 14a. More specifically, the first metal layer 15a is provided on the first main surface 14aa of the first dielectric film 14a so as to reach one side edge of the first dielectric film 14a in the second direction D2 but not reach the other side edge of the first dielectric film 14a.

[0028] Second metallized film 13b includes second dielectric film 14b and second metal layer 15b.

[0029] The second dielectric film 14b has a first main surface 14ba and a second main surface 14bb that face each other in the first direction D1.

[0030] The second metal layer 15b is provided on the first main surface 14ba of the second dielectric film 14b. More specifically, the second metal layer 15b is provided on the first main surface 14ba of the second dielectric film 14b so as not to reach one side edge of the second dielectric film 14b in the second direction D2 but to reach the other side edge of the second dielectric film 14b.

[0031] In the element body 11, adjacent first metallized films 13a and second metallized films 13b are offset in the second direction D2 so that the end of the first metal layer 15a that reaches the side edge of the first dielectric film 14a is exposed at one end surface of the element body 11, and the end of the second metal layer 15b that reaches the side edge of the second dielectric film 14b is exposed at the other end surface of the element body 11. That is, in adjacent first metallized films 13a and second metallized films 13b, the first metallized film 13a protrudes toward the first external electrode 12a relative to the second metallized film 13b. Also, in adjacent first metallized films 13a and second metallized films 13b, the second metallized film 13b protrudes toward the second external electrode 12b relative to the first metallized film 13a. In this state, the first metal layer 15a is connected to the first external electrode 12a but not to the second external electrode 12b. The second metal layer 15b is connected to the second external electrode 12b and is not connected to the first external electrode 12a.

[0032] In the element body 11, the adjacent first metallized films 13a and second metallized films 13b are offset in the second direction D2 as described above, so that, among the adjacent first dielectric films 14a and second dielectric films 14b, the first dielectric film 14a having the first metal layer 15a on its first main surface 14aa protrudes toward the first external electrode 12a relative to the second dielectric film 14b having the first metal layer 15a not provided on its main surface. Furthermore, among the adjacent first dielectric films 14a and second dielectric films 14b, the second dielectric film 14b having the second metal layer 15b on its first main surface 14ba protrudes toward the second external electrode 12b relative to the first dielectric film 14a having the second metal layer 15b not provided on its main surface.

[0033] Since element body 11 is formed by winding first metallized film 13a and second metallized film 13b in a stacked state in first direction D1, it can be said that element body 11 includes first dielectric film 14a, first metal layer 15a, second dielectric film 14b, and second metal layer 15b in this order in first direction D1. It can also be said that element body 11 is a wound body formed by winding first dielectric film 14a, first metal layer 15a, second dielectric film 14b, and second metal layer 15b in this order in first direction D1.

[0034] In element body 11, first main surface 14aa of first dielectric film 14a and second main surface 14bb of second dielectric film 14b face each other in first direction D1, and second main surface 14ab of first dielectric film 14a and first main surface 14ba of second dielectric film 14b face each other in first direction D1. Thus, in element body 11, first metallized film 13a and second metallized film 13b are wound in a stacked state in first direction D1. In other words, in element body 11, first metallized film 13a and second metallized film 13b are wound in a stacked state in first direction D1 so that second metallized film 13b is on the inside of first metallized film 13a, more specifically, so that first metal layer 15a is on the inside of first dielectric film 14a and second metal layer 15b is on the inside of second dielectric film 14b. That is, in the element body 11, the first metal layer 15a and the second metal layer 15b face each other with the first dielectric film 14a or the second dielectric film 14b sandwiched therebetween.

[0035] The first metal layer 15a may be provided with a fuse portion. The fuse portion provided in the first metal layer 15a is, for example, a portion that connects a divided electrode portion formed by dividing a portion of the first metal layer 15a that faces the second metal layer 15b into multiple portions with an electrode portion that does not face the second metal layer 15b. Examples of electrode patterns of the first metal layer 15a provided with a fuse portion include the electrode patterns disclosed in Japanese Patent Laid-Open Nos. 2004-363431 and 5-251266.

[0036] The second metal layer 15b may also be provided with a fuse portion, similar to the first metal layer 15a.

[0037] The first dielectric film 14a may contain a curable resin as a main component.

[0038] In this specification, the term "major component" means the component with the highest weight percentage, preferably a component with a weight percentage greater than 50% by weight.

[0039] The curable resin may be a thermosetting resin or a photocurable resin.

[0040] In this specification, thermosetting resin means a resin that can be cured by heat, but the curing method is not limited thereto. Therefore, thermosetting resins also include resins that can be cured by methods other than heat (e.g., light, electron beam, etc.) as long as they are resins that can be cured by heat. Furthermore, depending on the material, a reaction may be initiated due to the reactivity of the material itself, and resins that proceed to cure without necessarily being subjected to external heat or the like are also considered thermosetting resins. The same applies to photocurable resins; as long as they are resins that can be cured by light, they also include resins that can be cured by methods other than light (e.g., heat, etc.).

[0041] The curable resin is preferably a cured product of a first organic material having a hydroxyl group (OH group) and a second organic material having an isocyanate group (NCO group). In this case, the curable resin is a cured product having a urethane bond obtained by reacting the hydroxyl group of the first organic material with the isocyanate group of the second organic material.

[0042] The presence of urethane bonds in the dielectric film can be confirmed by analysis with a Fourier transform infrared spectrophotometer (FT-IR).

[0043] When the curable resin is obtained by the above-described reaction, uncured portions of the starting material may remain in the first dielectric film 14a. For example, the first dielectric film 14a may contain at least one of a hydroxyl group and an isocyanate group. In this case, the first dielectric film 14a may contain either a hydroxyl group or an isocyanate group, or may contain both a hydroxyl group and an isocyanate group.

[0044] The presence of hydroxyl groups and / or isocyanate groups in the dielectric film can be confirmed by FT-IR analysis.

[0045] Examples of the first organic material include phenoxy resin, polyvinyl acetoacetal resin, and polyvinyl butyral resin.

[0046] As the first organic material, a plurality of types of organic materials may be used in combination.

[0047] Examples of the second organic material include aromatic polyisocyanates such as diphenylmethane diisocyanate (MDI) and tolylene diisocyanate (TDI), and aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI). As the second organic material, at least one modified product of these polyisocyanates may be used, or a mixture of at least one modified product of these polyisocyanates may be used.

[0048] As the second organic material, a plurality of types of organic materials may be used in combination.

[0049] The first dielectric film 14a may contain a thermoplastic resin as a main component.

[0050] Examples of the thermoplastic resin include polypropylene, polyethersulfone, polyetherimide, and polyarylate.

[0051] The first dielectric film 14a may contain additives to impart various functions.

[0052] The additives include, for example, a leveling agent for imparting smoothness.

[0053] The additive preferably has a functional group that reacts with a hydroxyl group and / or an isocyanate group and forms part of the crosslinked structure of the cured product. Examples of such additives include resins having at least one functional group selected from the group consisting of a hydroxyl group, an epoxy group, a silanol group, and a carboxyl group.

[0054] Like the first dielectric film 14a, the second dielectric film 14b may contain a thermosetting resin as a main component, a photocurable resin as a main component, or a thermoplastic resin as a main component, and like the first dielectric film 14a, the second dielectric film 14b may also contain an additive.

[0055] The first dielectric film 14a and the second dielectric film 14b may have different compositions, but preferably have the same composition.

[0056] The thickness of the first dielectric film 14a and the second dielectric film 14b is preferably 1 μm or more and 10 μm or less, and more preferably 3 μm or more and 5 μm or less.

[0057] The thicknesses of the first dielectric film 14a and the second dielectric film 14b may be different from each other, but are preferably the same.

[0058] The thickness of the dielectric film is measured using an optical film thickness gauge.

[0059] The first dielectric film 14a and the second dielectric film 14b are each preferably produced by forming a resin solution containing the resin material as described above into a film and then curing it by heat treatment.

[0060] Examples of materials that can be used to form the first metal layer 15a and the second metal layer 15b include metals such as aluminum, zinc, titanium, magnesium, tin, and nickel.

[0061] The first metal layer 15a and the second metal layer 15b may have different compositions, but preferably have the same composition.

[0062] The thickness of the first metal layer 15a and the second metal layer 15b is preferably 5 nm or more and 40 nm or less.

[0063] The thickness of the first metal layer 15a and the second metal layer 15b may be different from each other, but it is preferable that they are the same.

[0064] The thickness of the metal layer is measured by observing a cross section of the metallized film along the first direction using a transmission electron microscope (TEM).

[0065] The first metal layer 15a and the second metal layer 15b are preferably formed by depositing the metals described above on the major surfaces of the first dielectric film 14a and the second dielectric film 14b, respectively.

[0066] The first external electrode 12a is provided on one end surface of the element body 11. More specifically, the first external electrode 12a is connected to the first metal layer 15a by contacting the end of the first metal layer 15a exposed on one end surface of the element body 11. On the other hand, the first external electrode 12a is not connected to the second metal layer 15b.

[0067] The second external electrode 12b is provided on the other end surface of the element body 11. More specifically, the second external electrode 12b is connected to the second metal layer 15b by contacting the end of the second metal layer 15b exposed on the other end surface of the element body 11. On the other hand, the second external electrode 12b is not connected to the first metal layer 15a.

[0068] Examples of materials that can be used to form the first external electrode 12a and the second external electrode 12b include metals such as zinc, aluminum, tin, and zinc-aluminum alloys.

[0069] The first external electrode 12a and the second external electrode 12b may have different compositions, but preferably have the same composition.

[0070] The first external electrode 12a and the second external electrode 12b are preferably formed by spraying the above-mentioned metal onto one end surface and the other end surface of the element body 11, respectively.

[0071] 2, the first lead terminal 20a is electrically connected to the first external electrode 12a. For example, the first lead terminal 20a is electrically connected to the first external electrode 12a via a joining member such as solder.

[0072] As shown in FIG. 2, the first lead terminal 20a may extend in a first direction D1.

[0073] 2, the second lead-out terminal 20b is electrically connected to the second external electrode 12b. For example, the second lead-out terminal 20b is electrically connected to the second external electrode 12b via a joining member such as solder.

[0074] As shown in FIG. 2, the second lead terminal 20b may extend in the first direction D1.

[0075] 2, the extending directions of the first and second lead-out terminals 20a and 20b may be parallel to each other, but the extending directions of the first and second lead-out terminals 20a and 20b do not have to be parallel to each other.

[0076] The first lead-out terminal 20a and the second lead-out terminal 20b may each have a plate-like or linear (rod-like) shape, for example. In this case, the first lead-out terminal 20a and the second lead-out terminal 20b may each have a partially bent shape.

[0077] Examples of materials for the first and second lead terminals 20a and 20b include metals such as copper, oxygen-free copper, aluminum, and alloys containing at least one of these. Among these, copper or oxygen-free copper is preferred as the material for the first and second lead terminals 20a and 20b. When the first and second lead terminals 20a and 20b are made of a copper-based material, examples of materials that can be used include oxygen-free copper (copper: 99.96% by weight or more), tough pitch copper (copper: 99.90% by weight or more), and phosphorus-deoxidized copper (copper: 99.90% by weight or more, phosphorus: 0.015% by weight or more, 0.040% by weight or less).

[0078] The first lead-out terminal 20a and the second lead-out terminal 20b are each used as a terminal for electrically connecting the capacitor element 10 to a mounting object when, for example, mounting the capacitor 1 on the mounting object.

[0079] As a method for electrically connecting the first lead terminal 20 a and the second lead terminal 20 b to the mounting object, for example, a welding method such as laser welding, resistance welding, etc. In particular, compared to other welding methods, laser welding has the advantage that welding can be completed in a short time by localized heating, and therefore welding distortion can be reduced.

[0080] As shown in FIGS. 1, 2, and 3, capacitor element 10 is housed inside metal case 30 so that first lead-out terminal 20a and second lead-out terminal 20b protrude outward.

[0081] The metal case 30 has a cylindrical shape with a bottom and an opening 31 at one end in the first direction D1, as shown in FIGS. 1, 2, and 3, for example.

[0082] In the example shown in Figures 2 and 3, the inner surface of the metal case 30 includes a first inner surface 32 facing the opening 31 in the first direction D1, and a second inner surface 33 (in the example shown in Figures 2 and 3, including four surfaces) extending from the first inner surface 32 toward the opening 31 in the first direction D1.

[0083] Examples of metals that can be used to form the metal case 30 include simple metals such as aluminum, magnesium, iron, stainless steel, and copper, and alloys containing at least one of these simple metals. Among these, it is preferable that the metal case 30 contains aluminum or an aluminum alloy.

[0084] The metal case 30 is manufactured by a method such as impact molding.

[0085] As shown in FIGS. 1, 2, and 3, the insulating member 40 is housed inside the metal case 30.

[0086] 2 and 3 , the insulating member 40 positions the capacitor element 10 so that the first lead-out terminal 20a does not come into contact with the metal case 30. Furthermore, the insulating member 40 positions the capacitor element 10 so that the second lead-out terminal 20b does not come into contact with the metal case 30.

[0087] In capacitor 1, insulating member 40 positions capacitor element 10 so that first lead-out terminal 20a does not contact metal case 30 and so that second lead-out terminal 20b does not contact metal case 30, thereby ensuring electrical insulation between capacitor element 10 and metal case 30. In this way, in capacitor 1, electrical insulation between capacitor element 10 and metal case 30 can be ensured by the simple structure of insulating member 40.

[0088] As shown in Fig. 2, the insulating member 40 may be provided between the first lead-out terminal 20a and the first inner surface 32 of the metal case 30 in the first direction D1. More specifically, as shown in Fig. 2, the insulating member 40 may have a first portion 40a provided between the first lead-out terminal 20a and the first inner surface 32 of the metal case 30 in the first direction D1. In the example shown in Fig. 2, the first portion 40a of the insulating member 40 extends in the second direction D2.

[0089] The insulating member 40 does not have to be provided between the first lead terminal 20a and the first inner surface 32 of the metal case 30 in the first direction D1.

[0090] 2, the insulating member 40 may be in contact with the first inner surface 32 of the metal case 30 in the first direction D1. More specifically, as shown in FIG. 2, the first portion 40a of the insulating member 40 may be in contact with the first inner surface 32 of the metal case 30 in the first direction D1.

[0091] As shown in Fig. 3 , the insulating member 40 may be in contact with the first inner surface 32 of the metal case 30 in the first direction D1. More specifically, as shown in Fig. 3 , the insulating member 40 may have a second portion 40b that is in contact with the first inner surface 32 of the metal case 30 in the first direction D1. In the example shown in Fig. 3 , the second portion 40b of the insulating member 40 extends in the third direction D3.

[0092] The insulating member 40 does not have to be in contact with the first inner surface 32 of the metal case 30 in the first direction D1.

[0093] As shown in Fig. 2, the insulating member 40 may be provided between the first lead-out terminal 20a and the second inner surface 33 of the metal case 30 in a second direction D2 that is perpendicular to the first direction D1. More specifically, as shown in Fig. 2, the insulating member 40 may have a third portion 40c provided between the first lead-out terminal 20a and the second inner surface 33 of the metal case 30 in the second direction D2. In the example shown in Fig. 2, the third portion 40c of the insulating member 40 extends in the first direction D1 while being connected to the first portion 40a.

[0094] The insulating member 40 does not have to be provided between the first lead terminal 20a and the second inner surface 33 of the metal case 30 in the second direction D2.

[0095] 2, the insulating member 40 may be in contact with the first lead-out terminal 20a in the second direction D2. More specifically, as shown in FIG. 2, the third portion 40c of the insulating member 40 may be in contact with the first lead-out terminal 20a in the second direction D2.

[0096] The insulating member 40 does not necessarily have to be in contact with the first lead terminal 20a in the second direction D2.

[0097] As shown in Fig. 2, the insulating member 40 may be provided between the second lead-out terminal 20b and the first inner surface 32 of the metal case 30 in the first direction D1. More specifically, as shown in Fig. 2, the insulating member 40 may have a fourth portion 40d provided between the second lead-out terminal 20b and the first inner surface 32 of the metal case 30 in the first direction D1. In the example shown in Fig. 2, the fourth portion 40d of the insulating member 40 extends in the second direction D2 at a position spaced apart from the first portion 40a.

[0098] The insulating member 40 does not have to be provided between the second lead terminal 20b and the first inner surface 32 of the metal case 30 in the first direction D1.

[0099] As shown in FIG. 2, the fourth portion 40d of the insulating member 40 may be in contact with the first inner surface 32 of the metal case 30 in the first direction D1.

[0100] 3, the insulating member 40 may have a fifth portion 40e that contacts the first inner surface 32 of the metal case 30 in the first direction D1. In the example shown in FIG. 3, the fifth portion 40e of the insulating member 40 extends in the third direction D3 at a position spaced apart from the second portion 40b.

[0101] The first portion 40a, the second portion 40b, the fourth portion 40d, and the fifth portion 40e of the insulating member 40 may be connected to each other, may not be connected to each other, or may not be connected in part.

[0102] As shown in Fig. 2, the insulating member 40 may be provided between the second lead-out terminal 20b and the second inner surface 33 of the metal case 30 in the second direction D2. More specifically, as shown in Fig. 2, the insulating member 40 may have a sixth portion 40f provided between the second lead-out terminal 20b and the second inner surface 33 of the metal case 30 in the second direction D2. In the example shown in Fig. 2, the sixth portion 40f of the insulating member 40 extends in the first direction D1 while being connected to the fourth portion 40d.

[0103] The insulating member 40 does not have to be provided between the second lead terminal 20b and the second inner surface 33 of the metal case 30 in the second direction D2.

[0104] 2, the insulating member 40 may be in contact with the second lead-out terminal 20b in the second direction D2. More specifically, as shown in FIG. 2, the sixth portion 40f of the insulating member 40 may be in contact with the second lead-out terminal 20b in the second direction D2.

[0105] The insulating member 40 does not necessarily have to be in contact with the second lead terminal 20b in the second direction D2.

[0106] Examples of the constituent material of the insulating member 40 include insulating materials such as resin and ceramic.

[0107] The insulating member 40 may be a member made of the insulating material described above, or may be a member in which a conductor made of a conductive material such as metal is covered with an insulating material.

[0108] 1, 2, and 3, the metal case 30 is filled with the filling resin 50 so as to embed the capacitor element 10. By filling the metal case 30 with the filling resin 50 in this manner, the capacitor element 10 is held inside the metal case 30.

[0109] 2 and 3 , when capacitor element 10 is housed inside metal case 30 so as to be spaced apart from the inner surface of metal case 30, filled resin 50 is filled between capacitor element 10 and metal case 30, more specifically, between the outer surface of capacitor element 10 and the inner surface of metal case 30. Furthermore, inside metal case 30, filled resin 50 is filled not only between capacitor element 10 and metal case 30, but also in the region from opening 31 of metal case 30 to capacitor element 10.

[0110] From the viewpoint of suppressing the penetration of moisture into capacitor element 10, it is preferable to appropriately select a resin with low moisture permeability as filling resin 50, such as epoxy resin, silicone resin, urethane resin, etc. Examples of the curing agent for epoxy resin include an amine curing agent, an imidazole curing agent, etc.

[0111] The above-mentioned resin alone may be used as the filling resin 50, but in order to improve strength, a resin to which a reinforcing agent has been added may also be used. Examples of the reinforcing agent include silica and alumina.

[0112] From the viewpoint of suppressing the infiltration of moisture into capacitor element 10, it is preferable that the thickness of filling resin 50 at opening 31 of metal case 30 is large. The thickness of filling resin 50 at opening 31 of metal case 30 is preferably sufficiently large within the range allowed for the overall volume (physical size) of capacitor 1, and specifically, is preferably 2 mm or more, and more preferably 4 mm or more. In particular, it is preferable that, inside metal case 30, capacitor element 10 is disposed closer to first inner surface 32 than to opening 31 of metal case 30, so that the thickness of filling resin 50 relative to capacitor element 10 is greater on the opening 31 side of metal case 30 than on the first inner surface 32 side.

[0113] The thickness of the filled resin 50 is measured, for example, using a soft X-ray device if it is in a non-destructive state, and using a length measuring device such as a caliper if it is in a destructive state.

[0114] The relationship between the height of the metal case 30 and the height of the filling resin 50 in the first direction D1 is such that the thickness of the filling resin 50 at the opening 31 of the metal case 30 is as large as possible, and it may be up to a position inside the metal case 30, or it may be just about to the top, or it may overflow slightly due to surface tension.

[0115] 2 and 3, the inner surface of the metal case 30 is provided with a protrusion 35 that protrudes toward the capacitor element 10 at a position where the insulating member 40 is not present. In other words, the protrusion 35 protrudes from the inner surface of the metal case 30 toward the element body 11 at a position where the insulating member 40 is not present.

[0116] As shown in FIG. 2, the shortest distance between capacitor element 10 and protrusion 35 is shorter than the shortest distance between first lead terminal 20 a and metal case 30 .

[0117] 2, the shortest distance between the capacitor element 10 and the protrusion 35 corresponds to the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35. In the example shown in Fig. 2, the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35 corresponds to the shortest distance in the first direction D1 between the body 11 of the capacitor element 10 and the protrusion 35.

[0118] 2 , the shortest distance between the first lead-out terminal 20a and the metal case 30 corresponds to the shortest distance F1 in the first direction D1 between the first lead-out terminal 20a and the metal case 30. Note that the shortest distance between the first lead-out terminal 20a and the metal case 30 may also correspond to the shortest distance in the second direction D2 between the first lead-out terminal 20a and the metal case 30. Alternatively, the shortest distance between the first lead-out terminal 20a and the metal case 30 may also correspond to the shortest distance in the third direction D3 between the first lead-out terminal 20a and the metal case 30.

[0119] In the example shown in FIG. 2, the shortest distance E between the capacitor element 10 and the protrusion 35 in the first direction D1 is smaller than the shortest distance F1 between the first lead terminal 20a and the metal case 30 in the first direction D1.

[0120] As shown in FIG. 2, the shortest distance between capacitor element 10 and protrusion 35 is smaller than the shortest distance between second lead terminal 20 b and metal case 30 .

[0121] 2 , the shortest distance between the second lead-out terminal 20b and the metal case 30 corresponds to the shortest distance F2 in the first direction D1 between the second lead-out terminal 20b and the metal case 30. Note that the shortest distance between the second lead-out terminal 20b and the metal case 30 may also correspond to the shortest distance in the second direction D2 between the second lead-out terminal 20b and the metal case 30. Alternatively, the shortest distance between the second lead-out terminal 20b and the metal case 30 may also correspond to the shortest distance in the third direction D3 between the second lead-out terminal 20b and the metal case 30.

[0122] In the example shown in FIG. 2, the shortest distance E between the capacitor element 10 and the protrusion 35 in the first direction D1 is smaller than the shortest distance F2 between the second lead terminal 20b and the metal case 30 in the first direction D1.

[0123] In the capacitor 1, the shortest distance between the capacitor element 10 and the protrusion 35 (in the example shown in FIG. 2 , the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35) is smaller than the shortest distance between the first lead-out terminal 20 a and the metal case 30 (in the example shown in FIG. 2 , the shortest distance F1 in the first direction D1 between the first lead-out terminal 20 a and the metal case 30) and the shortest distance between the second lead-out terminal 20 b and the metal case 30 (in the example shown in FIG. 2 , the shortest distance F2 in the first direction D1 between the second lead-out terminal 20 b and the metal case 30), and therefore the capacitor element 10 and the protrusion 35 are in close proximity (in the example shown in FIG. 2 , the capacitor element 10 and the protrusion 35 are in close proximity in the first direction D1). Therefore, in the capacitor 1, heat generated in the capacitor element 10 is more likely to diffuse to the protrusion 35, and the capacitor element 10 is more likely to be cooled. In this way, in the capacitor 1, the cooling function of the capacitor element 10 can be improved by the simple structure of the protrusions 35 provided on the inner surface of the metal case 30 (first inner surface 32 in the example shown in FIG. 2).

[0124] In capacitor 1, if the shortest distance between first lead-out terminal 20a and metal case 30 is equal to or shorter than the shortest distance between capacitor element 10 and protrusion 35, first lead-out terminal 20a and metal case 30 will come close to each other, causing discharge between first lead-out terminal 20a and metal case 30, impairing the capacitor's function. Also, in capacitor 1, if the shortest distance between second lead-out terminal 20b and metal case 30 is equal to or shorter than the shortest distance between capacitor element 10 and protrusion 35, second lead-out terminal 20b and metal case 30 will come close to each other, causing discharge between second lead-out terminal 20b and metal case 30, impairing the capacitor's function.

[0125] As described above, in the capacitor 1, the simple structure of the insulating member 40 and the protrusions 35 can ensure electrical insulation between the capacitor element 10 and the metal case 30 while improving the cooling function of the capacitor element 10.

[0126] In addition, as shown in FIG. 2 and other figures of Patent Document 1, the case-molded capacitor described in Patent Document 1 requires, in addition to the insulating and heat-transfer layer, a molding resin for molding the capacitor element and the insulating and heat-transfer layer. Therefore, the case-molded capacitor described in Patent Document 1 not only has a complex structure, but also presents problems such as difficulty in managing the manufacturing process. In contrast, Capacitor 1 can ensure electrical insulation between the capacitor element 10 and the metal case 30 and improve the cooling function of the capacitor element 10 simply by providing the simple structure of the insulating member 40 and the protrusions 35. Furthermore, Capacitor 1 simplifies the manufacturing process, making it easier to manage the manufacturing process.

[0127] The shortest distance between capacitor element 10 and protrusion 35 is preferably 0 mm or more and 5 mm or less. In the example shown in Fig. 2, the shortest distance E in the first direction D1 between capacitor element 10 and protrusion 35 is preferably 0 mm or more and 5 mm or less. In this case, in capacitor 1, capacitor element 10 and protrusion 35 are sufficiently close to each other, so that the cooling function of capacitor element 10 is sufficiently improved.

[0128] The shortest distance between the capacitor element 10 and the protrusion 35 is particularly preferably 0 mm. In the example shown in Fig. 2, the shortest distance E between the capacitor element 10 and the protrusion 35 in the first direction D1 is particularly preferably 0 mm. In other words, it is particularly preferable that the capacitor element 10 and the protrusion 35 are in contact with each other. In the example shown in Fig. 2, the capacitor element 10 and the protrusion 35 are separated from each other in the first direction D1, but it is particularly preferable that the capacitor element 10 and the protrusion 35 are in contact with each other in the first direction D1.

[0129] The shortest distance between the capacitor element and the protrusion is determined by observing a cross section of the capacitor at multiple points as shown in FIGS.

[0130] The shortest distance between the lead-out terminal and the metal case is determined by observing a cross section of the capacitor at multiple points as shown in FIG.

[0131] In terms of the cooling function of the capacitor element 10 , from the viewpoint of diffusing the heat generated in the capacitor element 10 to the protrusions 35 , it is preferable that the thermal conductivity of the metal case 30 (protrusions 35 ) be higher than the thermal conductivity of the filling resin 50 .

[0132] As shown in FIG. 2, the protrusion 35 may protrude from the first inner surface 32 of the metal case 30 in the first direction D1.

[0133] Although not shown in Figures 2 and 3, the protrusion 35 may protrude from the second inner surface 33 of the metal case 30 in the second direction D2, or may protrude from the second inner surface 33 of the metal case 30 in the third direction D3.

[0134] 2, the protrusion 35 may be in contact with the insulating member 40 in a second direction D2 that is perpendicular to the first direction D1. More specifically, as shown in Fig. 2, the protrusion 35 may be in contact with the first portion 40a and the fourth portion 40d of the insulating member 40 in the second direction D2. In this case, the insulating member 40 is positioned in the second direction D2 by the protrusion 35.

[0135] The protrusion 35 does not have to be in contact with the insulating member 40 in the second direction D2. More specifically, the protrusion 35 does not have to be in contact with the first portion 40a and the fourth portion 40d of the insulating member 40 in the second direction D2.

[0136] Alternatively, the protrusion 35 may be in contact with only one of the first portion 40a and the fourth portion 40d of the insulating member 40 in the second direction D2.

[0137] 3, the protrusion 35 may be in contact with the insulating member 40 in a third direction D3 that is perpendicular to the first direction D1 and the second direction D2. More specifically, as shown in FIG. 3, the protrusion 35 may be in contact with the second portion 40b and the fifth portion 40e of the insulating member 40 in the third direction D3. In this case, the insulating member 40 is positioned in the third direction D3 by the protrusion 35.

[0138] The protrusion 35 does not have to be in contact with the insulating member 40 in the third direction D3. More specifically, the protrusion 35 does not have to be in contact with the second portion 40b and the fifth portion 40e of the insulating member 40 in the third direction D3.

[0139] Alternatively, the protrusion 35 may be in contact with only one of the second portion 40b and the fifth portion 40e of the insulating member 40 in the third direction D3.

[0140] 2 , the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35 is preferably equal to or less than the shortest distance G in the first direction D1 between the capacitor element 10 and the insulating member 40. In this case, the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35 may be smaller than the shortest distance G in the first direction D1 between the capacitor element 10 and the insulating member 40, or may be the same as the shortest distance G in the first direction D1 between the capacitor element 10 and the insulating member 40. This brings the capacitor element 10 and the protrusion 35 sufficiently close to each other in the capacitor 1, thereby sufficiently improving the cooling function of the capacitor element 10.

[0141] 2 , if the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35 is smaller than the shortest distance G in the first direction D1 between the capacitor element 10 and the insulating member 40, the protrusion 35 will protrude in the first direction D1 relative to the insulating member 40. In other words, in the example shown in FIG. 2 , if the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35 is smaller than the shortest distance G in the first direction D1 between the capacitor element 10 and the insulating member 40, the surface of the protrusion 35 facing the capacitor element 10 will be at a height position closer to the capacitor element 10 in the first direction D1 than the surface of the insulating member 40 facing the capacitor element 10.

[0142] In the example shown in Figure 2, if the shortest distance E in the first direction D1 between the capacitor element 10 and the protrusion 35 is the same as the shortest distance G in the first direction D1 between the capacitor element 10 and the insulating member 40, the surfaces of the protrusion 35 and the insulating member 40 facing the capacitor element 10 will be at the same height position as each other in the first direction D1.

[0143] 2 , it is preferable that the dimension S of the protrusion 35 in the first direction D1 is equal to or greater than the dimension T of the insulating member 40 in the first direction D1. In this case, the dimension S of the protrusion 35 in the first direction D1 may be greater than the dimension T of the insulating member 40 in the first direction D1, or may be the same as the dimension T of the insulating member 40 in the first direction D1. This brings the capacitor element 10 and the protrusion 35 sufficiently close to each other in the capacitor 1, thereby sufficiently improving the cooling function of the capacitor element 10.

[0144] 2, when the dimension S of the protrusion 35 in the first direction D1 is larger than the dimension T of the insulating member 40 in the first direction D1, the protrusion 35 protrudes in the first direction D1 relative to the insulating member 40. In other words, in the example shown in Fig. 2, when the dimension S of the protrusion 35 in the first direction D1 is larger than the dimension T of the insulating member 40 in the first direction D1, the surface of the protrusion 35 facing the capacitor element 10 is at a height position closer to the capacitor element 10 in the first direction D1 than the surface of the insulating member 40 facing the capacitor element 10.

[0145] In the example shown in Figure 2, when the dimension S of the protrusion 35 in the first direction D1 is the same as the dimension T of the insulating member 40 in the first direction D1, the surfaces of the protrusion 35 and the insulating member 40 facing the capacitor element 10 are at the same height position in the first direction D1.

[0146] 2 and 3, the capacitor element 10 is spaced apart from the first inner surface 32 of the metal case 30. In this manner, in the capacitor 1, the state in which the capacitor element 10 is spaced apart from the first inner surface 32 of the metal case 30 can be achieved by, for example, the following methods 1 to 3.

[0147] (Method 1) While capacitor element 10 is lifted up by a jig or the like so as to be separated from first inner surface 32 of metal case 30, filling resin 50 is filled into metal case 30.

[0148] (Method 2) Protrusions that protrude in the second direction D2 are provided on the third portion 40c and the sixth portion 40f of the insulating member 40, and the capacitor element 10 is placed on the protrusions so as to be spaced apart from the first inner surface 32 of the metal case 30.

[0149] (Method 3) By tilting the extension direction of at least one of the third portion 40c and the sixth portion 40f of the insulating member 40 from the first direction D1, the distance in the second direction D2 between the third portion 40c and the sixth portion 40f is made smaller on the first inner surface 32 side of the metal case 30 than the total dimension in the second direction D2 of the capacitor element 10, the first lead-out terminal 20a, and the second lead-out terminal 20b, and then the capacitor element 10 is positioned away from the first inner surface 32 of the metal case 30.

[0150] In the examples shown in Figures 1, 2, and 3, one capacitor element 10 is housed inside one metal case 30, but multiple capacitor elements 10 may also be housed inside one metal case 30.

[0151] When multiple capacitor elements 10 are stored inside one metal case 30, it is sufficient for at least one capacitor element 10 to have the shortest distance between the capacitor element 10 and the protrusion 35 be smaller than the shortest distance between the first lead-out terminal 20a and the metal case 30 and the shortest distance between the second lead-out terminal 20b and the metal case 30, and it is particularly preferable that this be true for all capacitor elements 10.

[0152] When a plurality of capacitor elements 10 are housed inside one metal case 30, the protrusions 35 are naturally provided facing toward the capacitor elements 10, and may also be provided facing toward the spaces between adjacent capacitor elements 10. In this case, the adjacent capacitor elements 10 are both more likely to be cooled.

[0153] In the example shown in FIGS. 2 and 3, one protrusion 35 is provided facing one capacitor element 10, but a plurality of protrusions 35 may be provided facing one capacitor element 10.

[0154] When multiple protrusions 35 are provided toward one capacitor element 10, it is sufficient that the shortest distance between the capacitor element 10 and the protrusion 35 is smaller than the shortest distance between the first lead-out terminal 20a and the metal case 30 and the shortest distance between the second lead-out terminal 20b and the metal case 30 for at least one protrusion 35, and it is particularly preferable that this be true for all protrusions 35.

[0155] The capacitor of the present invention is useful, for example, as a smoothing capacitor constituting an on-vehicle power conversion device (for example, an inverter).

[0156] The present specification discloses the following:

[0157] <1> A capacitor comprising: a capacitor element having an element body and external electrodes provided on end faces of the element body; lead terminals electrically connected to the external electrodes; a metal case in which the capacitor element is housed so that the lead terminals protrude outward; an insulating member housed inside the metal case and positioning the capacitor element so that the lead terminals do not come into contact with the metal case; and a filling resin filled inside the metal case so as to embed the capacitor element; wherein the inner surface of the metal case is provided with a protrusion protruding toward the capacitor element at a position where the insulating member is not present; and the shortest distance between the capacitor element and the protrusion is shorter than the shortest distance between the lead terminals and the metal case.

[0158] <2> The capacitor according to <1>, wherein the shortest distance between the capacitor element and the protrusion is 0 mm or more and 5 mm or less.

[0159] <3> The capacitor according to <1> or <2>, wherein the metal case has a shape of a bottomed cylinder with an opening at one end in the first direction, and the inner surface of the metal case includes a first inner surface facing the opening in the first direction, and a second inner surface extending in the first direction from the first inner surface toward the opening.

[0160] <4> The capacitor according to <3>, wherein the lead-out terminal extends in the first direction.

[0161] <5> The capacitor according to <3> or <4>, wherein the insulating member is provided between the lead-out terminal and the first inner surface of the metal case in the first direction.

[0162] <6> The capacitor according to <5>, wherein the insulating member is in contact with the first inner surface of the metal case in the first direction.

[0163] <7> The capacitor according to any one of <3> to <6>, wherein the insulating member is provided between the lead-out terminal and the second inner surface of the metal case in a second direction perpendicular to the first direction.

[0164] <8> The capacitor according to <7>, wherein the insulating member is in contact with the lead terminal in the second direction.

[0165] <9> The capacitor according to any one of <3> to <8>, wherein the protrusion protrudes from the first inner surface of the metal case in the first direction.

[0166] <10> The capacitor according to any one of <3> to <9>, wherein the protrusion is in contact with the insulating member in a second direction perpendicular to the first direction.

[0167] <11> The capacitor according to any one of <3> to <10>, wherein the shortest distance in the first direction between the capacitor element and the protrusion is equal to or shorter than the shortest distance in the first direction between the capacitor element and the insulating member.

[0168] <12> The capacitor according to any one of <3> to <11>, wherein the dimension of the protrusion in the first direction is equal to or greater than the dimension of the insulating member in the first direction.

[0169] REFERENCE SIGNS LIST 1 capacitor 10 capacitor element 11 element body 12a first external electrode 12b second external electrode 13a first metallized film 13b second metallized film 14a first dielectric film 14aa first main surface of first dielectric film 14ab second main surface of first dielectric film 14b second dielectric film 14ba first main surface of second dielectric film 14bb second main surface of second dielectric film 15a first metal layer 15b second metal layer 20a first lead terminal 20b second lead terminal 30 metal case 31 opening 32 first inner surface 33 second inner surface 35 protrusion 40 insulating member 40a first portion 40b second portion 40c third portion 40d fourth portion 40e fifth portion 40f sixth portion 50 filled resin D1 first direction D2 second direction D3 Third direction E Shortest distance in the first direction between the capacitor element and the protrusion F1 Shortest distance in the first direction between the first lead-out terminal and the metal case F2 Shortest distance in the first direction between the second lead-out terminal and the metal case G Shortest distance in the first direction between the capacitor element and the insulating member S Dimension of the protrusion in the first direction T Dimension of the insulating member in the first direction

Claims

1. a capacitor element having an element body and external electrodes provided on end faces of the element body; A lead terminal electrically connected to the external electrode; a metal case in which the capacitor element is housed so that the lead-out terminal protrudes outward; an insulating member that is housed inside the metal case and that positions the capacitor element so that the lead terminals do not come into contact with the metal case; a filling resin filled inside the metal case so as to embed the capacitor element, at least a portion of the insulating member is provided between a portion of the lead-out terminal that extends toward the outside of the metal case and a portion of the metal case that faces the portion of the lead-out terminal; a protrusion is provided on an inner surface of the metal case at a position where the insulating member is not present, the protrusion protruding toward the capacitor element; A capacitor, wherein the shortest distance between the capacitor element and the protrusion is shorter than the shortest distance between the lead-out terminal and the metal case.

2. The capacitor according to claim 1 , wherein the shortest distance between the capacitor element and the protrusion is 0 mm or more and 5 mm or less.

3. The metal case has a bottomed cylindrical shape having an opening at one end in the first direction, The capacitor according to claim 1 or 2, wherein the inner surface of the metal case includes a first inner surface facing the opening in the first direction, and a second inner surface extending in the first direction from the first inner surface toward the opening.

4. The capacitor according to claim 3 , wherein the lead-out terminal extends in the first direction.

5. The capacitor according to claim 3 , wherein the insulating member is provided between the lead-out terminal and the first inner surface of the metal case in the first direction.

6. The capacitor according to claim 5 , wherein the insulating member is in contact with the first inner surface of the metal case in the first direction.

7. The capacitor according to claim 3 , wherein the insulating member is provided between the lead-out terminal and the second inner surface of the metal case in a second direction perpendicular to the first direction.

8. The capacitor according to claim 7 , wherein the insulating member is in contact with the lead-out terminal in the second direction.

9. The capacitor according to claim 3 , wherein the projection protrudes in the first direction from the first inner surface of the metal case.

10. The capacitor according to claim 3 , wherein the protrusion is in contact with the insulating member in a second direction perpendicular to the first direction.

11. The capacitor according to claim 3 , wherein a shortest distance in the first direction between the capacitor element and the protrusion is equal to or less than a shortest distance in the first direction between the capacitor element and the insulating member.

12. The capacitor according to claim 3 , wherein a dimension of the protrusion in the first direction is equal to or greater than a dimension of the insulating member in the first direction.