Capacitor element

Abstract

This capacitor element 1 comprises: a capacitor part 10 which includes a positive electrode plate 11 that has a porous part 11B on at least one main surface of a core part 11A, a dielectric layer 13 that is provided on the surface of the porous part 11B, and a negative electrode layer 12 that is provided on the surface of the dielectric layer 13; and a sealing layer 20 that is provided so as to cover at least one main surface of the capacitor part 10. The surface roughness R1 of a first portion on a first side surface of the porous part 11B exposed at a side edge end of the capacitor part 10 is higher than the surface roughness R2 of a second portion on a second side surface of the porous part 11B exposed in a recess that is provided on a main surface of the capacitor part 10.

Description

Capacitor element

[0001] The present invention relates to a capacitor element.

[0002] Patent Document 1 discloses a capacitor array including a plurality of solid electrolytic capacitor elements formed by dividing a single solid electrolytic capacitor sheet, a sheet-like first sealing layer, and a sheet-like second sealing layer. The solid electrolytic capacitor sheet includes an anode plate made of a valve metal, a porous layer provided on at least one main surface of the anode plate, a dielectric layer provided on the surface of the porous layer, and a cathode layer including a solid electrolyte layer provided on the surface of the dielectric layer, and has first and second main surfaces opposing each other in the thickness direction. The first main surface side of each of the plurality of solid electrolytic capacitor elements is disposed on the first sealing layer. The second sealing layer is disposed so as to cover the plurality of solid electrolytic capacitor elements on the first sealing layer from the second main surface side. The solid electrolytic capacitor elements are separated by slit-shaped sheet removal portions.

[0003] Japanese Patent Application Laid-Open No. 2020-167361

[0004] Patent Document 1 describes that a capacitor array may be placed in a cavity portion previously provided in a substrate, and then embedded with resin, and then a circuit layer may be formed on the resin.

[0005] However, if the adhesive strength between the insulating material such as resin (hereinafter referred to as the outer insulating layer) sealed in the cavity portion of the substrate and the capacitor array is insufficient, when force is applied to the outer insulating layer, there is a risk of delamination occurring between the outer insulating layer and the capacitor array.

[0006] The above problem is not limited to capacitor arrays in which a plurality of capacitor elements are covered with a sealing layer, but is a problem common to all capacitor elements in which at least one capacitor portion is covered with a sealing layer.

[0007] The present invention has been made to solve the above problems, and has an object to provide a capacitor element that has high adhesive strength with the outer insulating layer and is capable of suppressing delamination.

[0008] The capacitor element of the present invention comprises a capacitor section including an anode plate having a porous section on at least one main surface of a core section, a dielectric layer provided on the surface of the porous section, and a cathode layer provided on the surface of the dielectric layer, and a sealing layer provided so as to cover at least one main surface of the capacitor section, wherein a surface roughness R1 of a first portion of the porous section on a first side surface exposed at a side edge of the capacitor section is greater than a surface roughness R2 of a second portion of the porous section on a second side surface exposed in a recess provided in the main surface of the capacitor section.

[0009] According to the present invention, it is possible to provide a capacitor element that has high adhesive strength with the outer insulating layer and is capable of suppressing delamination.

[0010] Fig. 1 is a cross-sectional view schematically showing an example of a capacitor element of the present invention. Fig. 2 is a cross-sectional view taken along line II-II of the capacitor element shown in Fig. 1. Fig. 3 is a cross-sectional view schematically showing an example of a state in which an outer insulating layer is provided around the periphery of the capacitor element shown in Fig. 1. Figs. 4A and 4B are schematic views for explaining a method for measuring the length along the surface of a target portion.

[0011] The capacitor element of the present invention will be described below. Note that the present invention is not limited to the following embodiments and may be modified as appropriate within the scope of the present invention. Furthermore, a combination of multiple individual preferred configurations described in the following embodiments also constitutes the present invention.

[0012] In this specification, terms indicating the relationship between elements (e.g., "perpendicular," "parallel," "orthogonal," etc.) and terms indicating the shapes of elements are not expressions that only express a strict meaning, but are expressions that mean that a range of substantial equivalence, for example, a difference of about a few percent, is also included. Furthermore, in this specification, "equivalent" or "constant" is not an expression that means only completely equivalent or constant, but is an expression that means that a range of substantial equivalence or constant, for example, a difference of about a few percent, is included.

[0013] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, and other scales may differ from those of the actual product. In the drawings, the same or equivalent parts will be designated by the same reference numerals. In addition, the same elements will be designated by the same reference numerals in each drawing, and duplicate explanations will be omitted.

[0014] Fig. 1 is a cross-sectional view schematically showing an example of a capacitor element of the present invention, and Fig. 2 is a cross-sectional view taken along line II-II of the capacitor element shown in Fig. 1.

[0015] The capacitor element 1 shown in FIG. 1 includes a capacitor section 10 and a sealing layer 20 provided so as to cover at least one main surface of the capacitor section 10 .

[0016] The capacitor section 10 includes an anode plate 11 having a porous portion 11B on at least one main surface of a core portion 11A, a dielectric layer 13 provided on the surface of the porous portion 11B, and a cathode layer 12 provided on the surface of the dielectric layer 13. This makes up an electrolytic capacitor. In the example shown in Fig. 1, the anode plate 11 has the porous portion 11B on both main surfaces of the core portion 11A, but the porous portion 11B may be provided on only one main surface of the core portion 11A.

[0017] The cathode layer 12 includes, for example, a solid electrolyte layer 12A provided on the surface of the dielectric layer 13. The cathode layer 12 preferably further includes a conductor layer 12B provided on the surface of the solid electrolyte layer 12A. When the cathode layer 12 includes the solid electrolyte layer 12A, the capacitor section 10 constitutes a solid electrolytic capacitor.

[0018] The sealing layer 20 may be composed of only one layer or two or more layers. When the sealing layer 20 is composed of two or more layers, the materials constituting the respective layers may be the same or different.

[0019] As shown in Fig. 1 , the sealing layer 20 is preferably provided on both principal surfaces (top and bottom surfaces in Fig. 1 ) that face each other in the thickness direction (Z direction in Fig. 1 ) of the capacitor section 10. The sealing layer 20 protects the capacitor section 10.

[0020] The sealing layer 20 is formed so as to seal the capacitor portion 10 by, for example, a method of thermocompressing an insulating resin sheet, or a method of applying an insulating resin paste and then thermally curing it.

[0021] 1, the capacitor section 10 may further include an insulating mask layer 25 on at least one main surface of the anode plate 11. In this case, the insulating mask layer 25 is preferably provided in an area of ​​at least one main surface of the anode plate 11 where the cathode layer 12 is not formed.

[0022] The insulating mask layer 25 may be provided on at least one main surface of the anode plate 11 so as to surround the periphery of the cathode layer 12. By surrounding the periphery of the cathode layer 12 with the insulating mask layer 25, insulation between the anode plate 11 and the cathode layer 12 is ensured, and short-circuiting between them is prevented. The insulating mask layer 25 may be provided so as to surround a portion of the periphery of the cathode layer 12, or may be provided so as to surround the entire periphery of the cathode layer 12.

[0023] In the capacitor element 1, at least a portion of the side surface of the anode plate 11 (the left and right surfaces in FIG. 1 ) is not covered with the sealing layer 20. That is, at least a portion of the side surface of the anode plate 11 is exposed at the side edge of the capacitor section 10. As shown in FIGS. 1 and 2 , it is preferable that the entire side surface of the anode plate 11 is not covered with the sealing layer 20. That is, it is preferable that the entire side surface of the anode plate 11 is exposed at the side edge of the capacitor section 10.

[0024] The capacitor element 1 may further include a through conductor 30 provided to penetrate the capacitor portion 10 and the sealing layer 20 in the thickness direction. An insulating mask layer 25 may be provided around the through conductor 30 on at least one main surface of the anode plate 11.

[0025] The via conductors 30 may include a cathode via conductor 30A electrically connected to the cathode layer 12 .

[0026] As shown in FIG. 2, when viewed in the thickness direction, the cathode through conductor 30A is preferably provided around the entire periphery of a through hole that penetrates the capacitor section 10 and the sealing layer 20 in the thickness direction.

[0027] A first resin filling portion 35A filled with a resin material may be provided inside the cathode through conductor 30A. In this case, the first resin filling portion 35A is provided in a space surrounded by the cathode through conductor 30A in a through hole that penetrates the capacitor section 10 and the sealing layer 20 in the thickness direction. When the space in the through hole is eliminated by providing the first resin filling portion 35A, delamination of the cathode through conductor 30A is suppressed. Note that the first resin filling portion 35A may be a conductor or an insulator.

[0028] The cathode through conductor 30A is provided inside a cathode through hole 41 that passes through the capacitor section 10 in the thickness direction.

[0029] As shown in Fig. 1, it is preferable that an insulating material such as a sealing layer 20 is filled between the side wall surface of the anode plate 11 exposed in the cathode through-hole 41 and the cathode through-conductor 30A. In the example shown in Fig. 1 and Fig. 2, the sealing layer 20 is inserted between the side wall surface of the anode plate 11 exposed in the cathode through-hole 41 and the cathode through-conductor 30A.

[0030] The through conductors 30 may include an anode through conductor 30B electrically connected to the anode plate 11 .

[0031] 2 , as viewed in the thickness direction, the anode through conductor 30B is preferably provided around the entire periphery of a through hole that penetrates the capacitor section 10 and the sealing layer 20 in the thickness direction. The material constituting the anode through conductor 30B may be the same as or different from the material constituting the cathode through conductor 30A.

[0032] A second resin filling portion 35B filled with a resin material may be provided inside the anode through conductor 30B. In this case, the second resin filling portion 35B is provided in a space surrounded by the anode through conductor 30B in a through hole that penetrates the capacitor section 10 and the sealing layer 20 in the thickness direction. When the space in the through hole is eliminated by providing the second resin filling portion 35B, delamination of the anode through conductor 30B is suppressed. Note that the second resin filling portion 35B may be a conductor or an insulator.

[0033] The anode through conductor 30B is provided inside an anode through hole 43 that passes through the capacitor section 10 in the thickness direction.

[0034] As shown in FIG. 1, it is preferable that an insulating material such as a sealing layer 20 is not filled between the side wall surface of the anode plate 11 exposed in the anode through-hole 43 and the anode penetrating conductor 30B.

[0035] 1 , the anode through conductor 30B is preferably electrically connected to the side wall surface of the anode plate 11 exposed in the anode through hole 43. In other words, the anode through conductor 30B is preferably electrically connected to the anode plate 11 on the inner wall surface of the anode through hole 43.

[0036] The anode through conductor 30B may be electrically connected to the wall surface of the anode plate 11 via the anode connection layer 33. In this case, the anode connection layer 33 functions as a barrier layer for the anode plate 11, more specifically, as a barrier layer for the core portion 11A and the porous portion 11B. When the anode connection layer 33 functions as a barrier layer for the anode plate 11, dissolution of the anode plate 11 that occurs during chemical treatment for forming a wiring layer (described later) is suppressed, and therefore penetration of the chemical solution into the capacitor portion 10 is suppressed, which tends to improve reliability.

[0037] The anode connection layer 33 preferably includes a metal layer containing nickel as a main component. In this case, damage to the metal (e.g., aluminum) constituting the anode plate 11 is reduced, and the barrier properties of the anode connection layer 33 against the anode plate 11 are likely to be improved.

[0038] For example, the anode connecting layer 33 including a metal layer mainly composed of nickel can be formed by performing a zincate treatment on the wall surface of the anode plate 11 made of aluminum or an aluminum alloy, followed by electroless nickel plating. The anode connecting layer 33 may include, in order from the anode plate 11, a metal layer mainly composed of zinc and a metal layer mainly composed of nickel.

[0039] The dimension of the anode connection layer 33 in the thickness direction of the anode plate 11 (Z direction in Figure 1) may be equal to the dimension of the anode plate 11 in the thickness direction, may be smaller than the dimension of the anode plate 11 in the thickness direction, or may be larger than the dimension of the anode plate 11 in the thickness direction.

[0040] The anode through conductor 30B may be connected directly to the side wall surface of the anode plate 11 without the anode connection layer 33 therebetween.

[0041] The planar shape of the cathode through-conductor 30A (for example, the cross-sectional shape perpendicular to the thickness direction of the anode plate 11) is not particularly limited and may be, for example, a circular shape. Similarly, the planar shape of the anode through-conductor 30B is not particularly limited and may be, for example, a circular shape. The planar shape of the cathode through-conductor 30A may be the same as or different from the planar shape of the anode through-conductor 30B.

[0042] The cathode through conductor 30A preferably exists within the cathode layer 12 in a plan view in the thickness direction of the anode plate 11. Similarly, the anode through conductor 30B preferably exists within the cathode layer 12 in a plan view in the thickness direction of the anode plate 11.

[0043] The number of cathode through conductors 30A may be the same as the number of anode through conductors 30B, may be less than the number of anode through conductors 30B, or may be more than the number of anode through conductors 30B.

[0044] The diameter of the cathode through conductor 30A may be equal to the diameter of the anode through conductor 30B, may be smaller than the diameter of the anode through conductor 30B, or may be larger than the diameter of the anode through conductor 30B.

[0045] In this specification, the diameter of a through hole means the diameter when the planar shape is circular, and means the equivalent circle diameter when the planar shape is other than circular.

[0046] The diameter of the cathode through conductor 30A may be constant or may vary in the thickness direction. Similarly, the diameter of the anode through conductor 30B may be constant or may vary in the thickness direction.

[0047] Although not shown, the capacitor element 1 may further include a through conductor 30 that is not electrically connected to either the anode plate 11 or the cathode layer 12 .

[0048] The capacitor element 1 may be provided with a through groove 45 that passes through the capacitor portion 10 in the thickness direction. The through groove 45 divides the anode plate 11.

[0049] 1, the through groove 45 is preferably filled with an insulating material such as a sealing layer 20. In the example shown in FIGS.

[0050] The direction in which the through grooves 45 extend is not particularly limited. For example, the through grooves 45 may extend in the X direction in Figures 1 and 2, or in the Y direction, or in a direction intersecting the X direction or the Y direction. The number of through grooves 45 is not particularly limited, and may be one, or two or more. The through grooves 45 may be linear, curved, or bent.

[0051] The width of the through groove 45 may be constant or may vary in the thickness direction. The through groove 45 may be arranged so as to cross the anode plate 11, or may be arranged so as not to cross the anode plate 11.

[0052] 1, a wiring layer 50 may be provided on at least one main surface of the sealing layer 20. In the example shown in Fig. 1, the wiring layer 50 is provided on both main surfaces of the sealing layer 20 (top and bottom surfaces in Fig. 1), but the wiring layer 50 may be provided on either one of the main surfaces of the sealing layer 20 (top or bottom surface in Fig. 1).

[0053] The wiring layer 50 may include a first wiring layer 50A electrically connected to the cathode through conductor 30A. In the example shown in FIG. 1 , the first wiring layer 50A is electrically connected to the cathode layer 12 through a via conductor 55 that penetrates the sealing layer 20.

[0054] The wiring layer 50 may include a second wiring layer 50B electrically connected to the anode penetrating conductor 30B. In the example shown in Fig. 1, the second wiring layer 50B is electrically connected to the anode plate 11 via the anode penetrating conductor 30B.

[0055] FIG. 3 is a cross-sectional view schematically showing an example of a state in which an outer insulating layer is provided around the periphery of the capacitor element shown in FIG.

[0056] For example, when the capacitor element 1 shown in FIG. 1 is embedded in a substrate, an outer insulating layer 60 is provided around the capacitor element 1 as shown in FIG.

[0057] The outer insulating layer 60 is provided so as to cover the capacitor section 10 and the sealing layer 20 of the capacitor element 1. When the wiring layer 50 is provided on at least one main surface of the sealing layer 20, the outer insulating layer 60 is provided so as to cover the capacitor section 10, the sealing layer 20, and the wiring layer 50.

[0058] The outer insulating layer 60 is made of an insulating material.

[0059] The outer insulating layer 60 is formed, for example, by placing the capacitor element 1 in a cavity portion previously provided in the substrate and embedding it with insulating resin.

[0060] Alternatively, the outer insulating layer 60 may be formed, for example, by attaching a cured prepreg to the capacitor element 1 via an adhesive layer.

[0061] The outer insulating layer 60 may be composed of only one layer or two or more layers. When the outer insulating layer 60 is composed of two or more layers, the materials constituting each layer may be the same or different.

[0062] The outer insulating layer 60 may be provided on only one surface of the capacitor element 1 in the thickness direction, or on both surfaces.

[0063] An outer circuit layer 65 may be provided inside the outer insulating layer 60 .

[0064] The capacitor element 1 shown in Figures 1 to 3 is characterized in that the surface roughness R1 of a first portion of a first side surface of the porous portion 11B exposed at the side edge of the capacitor portion 10 is greater than the surface roughness R2 of a second portion of a second side surface of the porous portion 11B exposed in a recess provided on the main surface of the capacitor portion 10.

[0065] Here, the recess provided on the main surface of the capacitor section 10 may be a portion that does not penetrate the capacitor section 10 in the thickness direction, or may be a portion that penetrates the capacitor section 10 in the thickness direction. In particular, the recess is preferably a cathode through-hole 41 or a through groove 45. On the other hand, in this specification, an anode through-hole 43 is not included in the recess.

[0066] The first portion of the first side surface of porous portion 11B is, for example, the portion indicated by A in Fig. 3. The first portion does not need to be the entire first side surface of porous portion 11B exposed at the side edge of capacitor portion 10, but may be only a portion. The position and size of the first portion are not particularly limited.

[0067] The second portion on the second side surface of porous portion 11B is, for example, the portion indicated by B or C in Fig. 3. The second portion does not need to be the entire second side surface of porous portion 11B exposed in a recess provided in the main surface of capacitor portion 10, but may be only a portion. The position and size of the second portion are not particularly limited.

[0068] When an outer insulating layer 60 is provided around the capacitor element 1, the bonding strength between the metal constituting the anode plate 11 exposed at the side edge of the capacitor section 10 and the resin constituting the outer insulating layer 60 is low, so when force is applied to the outer insulating layer 60, delamination is likely to occur between the capacitor section 10 and the outer insulating layer 60.

[0069] Therefore, by roughening the side surface of the anode plate 11 exposed at the side edge of the capacitor section 10, the surface roughness R1 of a first portion of the first side surface of the porous section 11B exposed at the side edge of the capacitor section 10 is made larger than the surface roughness R2 of a second portion of the second side surface of the porous section 11B exposed in a recess provided in the main surface of the capacitor section 10. This increases the adhesion strength between the anode plate 11 and the outer insulating layer 60, thereby suppressing delamination between the capacitor section 10 and the outer insulating layer 60.

[0070] For example, the surface roughness R1 of a first portion of the first side surface of the porous portion 11B exposed at the side edge of the capacitor portion 10 may be larger than the surface roughness R2 of a second portion of the second side surface of the porous portion 11B exposed at the cathode through-hole 41 of the capacitor portion 10, and may also be larger than the surface roughness R2 of a second portion of the second side surface of the porous portion 11B exposed at the through groove 45 of the capacitor portion 10. Alternatively, the surface roughness R1 of the first portion of the first side surface of the porous portion 11B exposed at the side edge of the capacitor portion 10 may be larger than the surface roughness R2 of a second portion of the second side surface of the porous portion 11B exposed at the cathode through-hole 41 of the capacitor portion 10, and may also be larger than the surface roughness R2 of the second portion of the second side surface of the porous portion 11B exposed at the through groove 45 of the capacitor portion 10.

[0071] When a wiring layer 50 is provided on at least one main surface of the sealing layer 20, it is preferable that the surface roughness R3 of the third portion on the surface of the wiring layer 50 is greater than the surface roughness R2 of the second portion on the second side surface of the porous portion 11B.

[0072] The third portion on the surface of the wiring layer 50 is, for example, the portion indicated by D in Fig. 3. The third portion does not need to be the entire surface of the wiring layer 50, but may be a portion. The position and size of the third portion are not particularly limited.

[0073] When a wiring layer 50 is provided on at least one main surface of the sealing layer 20, the bonding strength between the metal constituting the wiring layer 50 and the resin constituting the outer insulating layer 60 is low, so when force is applied to the outer insulating layer 60, delamination is likely to occur between the wiring layer 50 and the outer insulating layer 60.

[0074] Therefore, by roughening the surface of the wiring layer 50, the surface roughness R3 of the third portion on the surface of the wiring layer 50 is made larger than the surface roughness R2 of the second portion on the second side surface of the porous portion 11B. This increases the adhesion strength between the wiring layer 50 and the outer insulating layer 60, thereby further suppressing delamination between the capacitor portion 10 and the outer insulating layer 60.

[0075] For example, when the wiring layer 50 includes a first wiring layer 50A and a second wiring layer 50B, the surface roughness R3 of the third portion of the surface of the first wiring layer 50A may be greater than the surface roughness R2 of the second portion of the second side surface of the porous portion 11B, and the surface roughness R3 of the third portion of the surface of the second wiring layer 50B may be greater than the surface roughness R2 of the second portion of the second side surface of the porous portion 11B. Alternatively, the surface roughness R3 of the third portion of the surface of the first wiring layer 50A may be greater than the surface roughness R2 of the second portion of the second side surface of the porous portion 11B, and the surface roughness R3 of the third portion of the surface of the second wiring layer 50B may be greater than the surface roughness R2 of the second portion of the second side surface of the porous portion 11B.

[0076] When the wiring layer 50 is provided on at least one main surface of the sealing layer 20, it is more preferable that the surface roughness R3 of the third portion on the surface of the wiring layer 50 is greater than the surface roughness R1 of the first portion on the first side surface of the porous portion 11B. In this case, the adhesion strength between the wiring layer 50 and the outer insulating layer 60 can be further increased.

[0077] For example, when the wiring layer 50 includes a first wiring layer 50A and a second wiring layer 50B, the surface roughness R3 of the third portion on the surface of the first wiring layer 50A may be greater than the surface roughness R1 of the first portion on the first side surface of the porous portion 11B, and the surface roughness R3 of the third portion on the surface of the second wiring layer 50B may be greater than the surface roughness R1 of the first portion on the first side surface of the porous portion 11B. Alternatively, the surface roughness R3 of the third portion on the surface of the first wiring layer 50A may be greater than the surface roughness R1 of the first portion on the first side surface of the porous portion 11B, and the surface roughness R3 of the third portion on the surface of the second wiring layer 50B may be greater than the surface roughness R1 of the first portion on the first side surface of the porous portion 11B.

[0078] 3, the roughened portions of the side surface of the anode plate 11 and the surface of the wiring layer 50 are indicated by dashed lines. As indicated by the dashed lines in FIG. 3, it is preferable that the entire portions of the side surface of the anode plate 11 and the surface of the wiring layer 50 that contact the outer insulating layer 60 are roughened, but it is also possible that some of the portions that contact the outer insulating layer 60 are not roughened.

[0079] The method for roughening the side surface of the anode plate 11 and the surface of the wiring layer 50 is not particularly limited, and examples include a method in which the Brown treatment performed when forming the wiring layer 50 is performed not only on the surface of the wiring layer 50 but also on the side surface of the anode plate 11.

[0080] The third portion of the surface of the wiring layer 50 is preferably a portion of the surface of the wiring layer 50 that is not connected to the external circuit layer 65 .

[0081] Of the surface of the wiring layer 50, it is preferable that the surface roughness of the portion connected to the external circuit layer 65 (for example, the portion indicated by E in FIG. 3 ) is smaller than the surface roughness of the portion not connected to the external circuit layer 65 (for example, the portion indicated by D in FIG. 3 ). In this case, the connectivity between the via conductors constituting the external circuit layer 65 and the wiring layer 50 is improved. Note that the positions and sizes of the portions for which the surface roughness is compared are not particularly limited.

[0082] At least one of the main surfaces of sealing layer 20 may be roughened. For example, the surface roughness of the main surface of sealing layer 20 (e.g., the portion indicated by F in FIG. 3 ) may be greater than the surface roughness of the side surface of sealing layer 20 (e.g., the portion indicated by G in FIG. 3 ). Note that the positions and sizes of the portions for comparing the surface roughness are not particularly limited.

[0083] As an index of the surface roughness of each portion, the length along the surface of each portion (also referred to as the rough surface length) measured from an image taken under the following conditions can be used.

[0084] 4A and 4B are schematic diagrams illustrating a method for measuring the length along the surface of a target portion.

[0085] As shown in Figure 4A, a cross section of the target portion along the thickness direction is photographed using a scanning electron microscope (SEM) with an acceleration voltage of 2.5 kV (preferably about 1 to 3 kV) and a magnification of 25,000 times.

[0086] As shown in Figure 4B, the length along the surface of the target portion (the length indicated by L in Figure 4B) is measured using image processing software or the like for the obtained SEM image. Furthermore, the length of the reference line RL (Reference Line) perpendicular to the thickness direction of the capacitor portion is measured in the obtained SEM image. ImageJ, for example, can be used as the image processing software.

[0087] As an index of the surface roughness R1 of the first portion on the first side surface of the porous portion 11B, the length L1 along the surface of the first portion is preferably 2 to 2.5 times the length L0 of the reference line RL. The length L1 along the surface of the first portion is preferably 6 μm to 8.5 μm.

[0088] As an index of the surface roughness R2 of the second portion on the second side surface of the porous portion 11B, the length L2 along the surface of the second portion is preferably 1.8 times or less the length L0 of the reference line RL. Meanwhile, the length L2 along the surface of the second portion only needs to be 1 time or more the length L0 of the reference line RL, and is preferably greater than 1 time. The length L2 along the surface of the second portion is preferably 5 μm or less. Meanwhile, the length L2 along the surface of the second portion is preferably 3.6 μm or more.

[0089] As an index of the surface roughness R3 of the third portion on the surface of the wiring layer 50, the length L3 along the surface of the third portion is preferably 2.7 times or more the length L0 of the reference line RL. On the other hand, the length L3 along the surface of the third portion is preferably 3.5 times or less the length L0 of the reference line RL. The length L3 along the surface of the third portion is preferably 10 μm or more and 30 μm or less.

[0090] Although not shown, a metal coating layer such as a plating layer may be provided on at least a portion of the side surface of the anode plate 11 exposed at the side edge of the capacitor section 10. In this case, the metal coating layer functions as a barrier layer for the anode plate 11, more specifically, as a barrier layer for the core section 11A and the porous section 11B.

[0091] The surface of the metal coating layer may be roughened when the metal coating layer is provided on the side surface of the anode plate 11. The surface roughness of the metal coating layer may be equal to, smaller than, or larger than the surface roughness R1 of the first portion of the porous portion 11B on the first side surface.

[0092] For example, the anode plate 11 is preferably made of aluminum or an aluminum alloy, and the metal coating layer preferably includes a layer containing nickel as a main component. Note that the "main component" refers to the element component with the largest weight ratio.

[0093] For example, a metal coating layer mainly composed of nickel can be formed by zincating the side surface of the anode plate 11 made of aluminum or an aluminum alloy and then electroless nickel plating it. The metal coating layer may include, in order from the anode plate 11, a layer mainly composed of zinc and a layer mainly composed of nickel.

[0094] The dimensions of the metal coating layer in the thickness direction of the anode plate 11 may be equal to the dimensions of the anode plate 11 in the thickness direction, may be smaller than the dimensions of the anode plate 11 in the thickness direction, or may be larger than the dimensions of the anode plate 11 in the thickness direction.

[0095] The detailed configuration of the capacitor element 1 will be described below.

[0096] One capacitor section 10 or a plurality of capacitor sections 10 may be disposed inside sealing layer 20. When a plurality of capacitor sections 10 are disposed inside sealing layer 20, adjacent capacitor sections 10 are preferably separated from each other by a through groove 45 that penetrates capacitor section 10 in the thickness direction. In this case, through groove 45 is preferably filled with an insulating material such as sealing layer 20.

[0097] When adjacent capacitor sections 10 are separated by through groove 45, it is sufficient that the adjacent capacitor sections 10 are physically separated by through groove 45. Therefore, adjacent capacitor sections 10 may be electrically separated or electrically connected. The width of through groove 45, i.e., the distance between adjacent capacitor sections 10, may be constant in the thickness direction or may decrease in the thickness direction.

[0098] When multiple capacitor sections 10 are arranged inside sealing layer 20, the multiple capacitor sections 10 may be arranged side by side in a plane direction perpendicular to the thickness direction, may be arranged so as to be stacked in the thickness direction, or may be arranged in a combination of both. The multiple capacitor sections 10 may be arranged regularly or irregularly. The size, shape, etc. of the capacitor sections 10 may be the same, or some or all of them may be different. It is preferable that the configuration of each capacitor section 10 is the same, but capacitor sections 10 with different configurations may be included.

[0099] Examples of the planar shape of the capacitor section 10 when viewed from the thickness direction include a rectangle (square or oblong), a quadrangle other than a rectangle, a polygon such as a triangle, a pentagon, or a hexagon, a circle, an ellipse, a combination of these, etc. The planar shape of the capacitor section 10 may also be an L-shape, a C-shape, a stepped shape, etc.

[0100] The anode plate 11 is preferably made of a valve metal that exhibits so-called valve action. Examples of the valve metal include simple metals such as aluminum, tantalum, niobium, titanium, and zirconium, and alloys containing at least one of these metals. Among these, aluminum or an aluminum alloy is preferred.

[0101] The shape of the anode plate 11 is preferably a flat plate, and more preferably a foil. Thus, in this specification, the term "plate-like" includes "foil-like".

[0102] The anode plate 11 may have the porous portion 11B on at least one main surface of the core portion 11A. That is, the anode plate 11 may have the porous portion 11B on only one main surface of the core portion 11A, or may have the porous portion 11B on both main surfaces of the core portion 11A. The porous portion 11B is preferably a porous layer formed on the surface of the core portion 11A, and more preferably an etched layer.

[0103] The thickness of the anode plate 11 before etching is preferably 60 μm or more and 200 μm or less. The thickness of the unetched core portion 11A after etching is preferably 15 μm or more and 70 μm or less. The thickness of the porous portion 11B is designed according to the required withstand voltage and electrostatic capacitance, but the combined thickness of the porous portions 11B on both sides of the core portion 11A is preferably 10 μm or more and 180 μm or less.

[0104] The pore diameter of the porous portion 11B is preferably 10 nm or more and 600 nm or less. The pore diameter of the porous portion 11B refers to the median diameter D50 measured with a mercury porosimeter. The pore diameter of the porous portion 11B can be controlled, for example, by adjusting various etching conditions.

[0105] The dielectric layer 13 provided on the surface of the porous portion 11B is porous, reflecting the surface condition of the porous portion 11B, and has a finely uneven surface shape. The dielectric layer 13 is preferably made of an oxide film of the valve metal. For example, when aluminum foil is used as the anode plate 11, the dielectric layer 13 made of an oxide film can be formed by anodizing the surface of the aluminum foil in an aqueous solution containing ammonium adipate or the like (also called chemical conversion treatment).

[0106] The thickness of the dielectric layer 13 is designed according to the required withstand voltage and capacitance, but is preferably 10 nm or more and 100 nm or less.

[0107] When the cathode layer 12 includes a solid electrolyte layer 12A, examples of materials constituting the solid electrolyte layer 12A include conductive polymers such as polypyrroles, polythiophenes, and polyanilines. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene), also known as PEDOT, is particularly preferred. The conductive polymer may also contain a dopant such as polystyrene sulfonate (PSS). The solid electrolyte layer 12A preferably includes an inner layer that fills the pores (recesses) of the dielectric layer 13 and an outer layer that covers the dielectric layer 13.

[0108] The thickness of the solid electrolyte layer 12A from the surface of the porous portion 11B is preferably 2 μm or more and 20 μm or less.

[0109] The solid electrolyte layer 12A is formed, for example, by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the dielectric layer 13 using a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or by a method of applying a dispersion liquid of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer 13 and drying it.

[0110] The solid electrolyte layer 12A can be formed in a predetermined region by applying the above-mentioned treatment liquid or dispersion liquid to the surface of the dielectric layer 13 by a method such as sponge transfer, screen printing, dispenser application, or inkjet printing.

[0111] When the cathode layer 12 includes the conductor layer 12B, the conductor layer 12B includes at least one layer selected from a conductive resin layer and a metal layer. The conductor layer 12B may be composed of only a conductive resin layer or only a metal layer. The conductor layer 12B preferably covers the entire surface of the solid electrolyte layer 12A.

[0112] The conductive resin layer may be, for example, a conductive adhesive layer containing at least one conductive filler selected from the group consisting of silver filler, copper filler, nickel filler, and carbon filler.

[0113] Examples of the metal layer include a metal plating film and a metal foil. The metal layer is preferably made of at least one metal selected from the group consisting of nickel, copper, silver, and alloys containing these metals as the main component. The term "main component" refers to the elemental component with the largest weight ratio.

[0114] The conductor layer 12B includes, for example, a carbon layer provided on the surface of the solid electrolyte layer 12A and a copper layer provided on the surface of the carbon layer.

[0115] The carbon layer is provided to electrically and mechanically connect the solid electrolyte layer 12A and the copper layer. The carbon layer can be formed in a predetermined region by applying a carbon paste to the surface of the solid electrolyte layer 12A by sponge transfer, screen printing, dispenser application, inkjet printing, or other methods. The thickness of the carbon layer is preferably 2 μm or more and 20 μm or less.

[0116] The copper layer can be formed in a predetermined region by applying a copper paste to the surface of the carbon layer by sponge transfer, screen printing, spray coating, dispenser coating, inkjet printing, etc. The thickness of the copper layer is preferably 2 μm or more and 20 μm or less.

[0117] The cathode through conductor 30A is formed, for example, as follows. First, a cathode through hole 41 penetrating the capacitor unit 10 in the thickness direction is formed by drilling, laser processing, or the like. Next, an insulating material such as a sealing layer 20 is filled into the cathode through hole 41. A through hole is formed by drilling, laser processing, or the like in the portion filled with the insulating material. At this time, a through hole having a smaller diameter than the cathode through hole 41 filled with the insulating material is formed, so that the insulating material is present in the planar direction between the inner wall surface of the subsequently formed through hole and the inner wall surface of the cathode through hole 41. Then, the inner wall surface of the through hole formed after the cathode through hole 41 is metallized with a metal material containing a low-resistance metal such as copper, gold, or silver, thereby forming the cathode through conductor 30A. When forming the cathode through conductor 30A, for example, metallizing the inner wall surface of the through hole by a process such as electroless copper plating or electrolytic copper plating facilitates processing. The cathode through conductor 30A may be formed by filling the through hole with a metal material, a composite material of metal and resin, or the like, in addition to metallizing the inner wall surface of the through hole.

[0118] The anode through conductor 30B is formed, for example, as follows. First, an anode through hole 43 is formed by drilling, laser processing, or other processing, penetrating the sealing layer 20 and the capacitor unit 10 in the thickness direction. The inner wall surface of the through hole is then metallized with a metal material containing a low-resistance metal such as copper, gold, or silver, to form the anode through conductor 30B. When forming the anode through conductor 30B, for example, metallizing the inner wall surface of the through hole by a process such as electroless copper plating or electrolytic copper plating facilitates processing. Note that the method of forming the anode through conductor 30B may include, in addition to a method of metallizing the inner wall surface of the through hole, a method of filling the through hole with a metal material, a composite material of metal and resin, or the like.

[0119] The sealing layer 20 is made of an insulating material. In this case, the sealing layer 20 preferably contains an insulating resin.

[0120] Examples of the insulating resin contained in the sealing layer 20 include epoxy resin and phenol resin.

[0121] Preferably, the sealing layer 20 further contains a filler.

[0122] Examples of the filler contained in the sealing layer 20 include inorganic fillers such as silica particles and alumina particles.

[0123] Between the capacitor section 10 and the sealing layer 20, for example, a stress relaxation layer, a moisture-proof film, or the like may be provided.

[0124] The insulating mask layer 25 is made of an insulating material, and in this case, the insulating mask layer 25 preferably contains an insulating resin.

[0125] Examples of insulating resins contained in the insulating mask layer 25 include polyphenylsulfone resin, polyethersulfone resin, cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, etc.), polyimide resin, polyamideimide resin, epoxy resin, and derivatives or precursors thereof.

[0126] The insulating mask layer 25 may be made of the same resin as the sealing layer 20. Unlike the sealing layer 20, if the insulating mask layer 25 contains an inorganic filler, it may adversely affect the effective capacitance portion of the capacitor section 10. Therefore, it is preferable that the insulating mask layer 25 be made of a resin alone.

[0127] The insulating mask layer 25 can be formed in a predetermined area by applying a mask material, such as a composition containing an insulating resin, to the surface of the porous portion 11B by a method such as sponge transfer, screen printing, dispenser application, or inkjet printing.

[0128] The insulating mask layer 25 may be formed on the porous portion 11B either before or after the dielectric layer 13 is formed.

[0129] Examples of the constituent material of the first wiring layer 50A include metal materials containing low-resistance metals such as silver, gold, copper, etc. In this case, the first wiring layer 50A is formed by, for example, plating the surface of the cathode through conductor 30A.

[0130] In order to improve the adhesion between the first wiring layer 50A and other members, in this case, the adhesion between the first wiring layer 50A and the cathode through conductor 30A, a mixed material of at least one conductive filler selected from the group consisting of silver filler, copper filler, nickel filler, and carbon filler and a resin may be used as a constituent material of the first wiring layer 50A.

[0131] Examples of the constituent material of the second wiring layer 50B include metal materials containing low-resistance metals such as silver, gold, copper, etc. In this case, the second wiring layer 50B is formed by, for example, plating the surface of the anode penetrating conductor 30B.

[0132] In order to improve the adhesion between the second wiring layer 50B and other members, in this case, the adhesion between the second wiring layer 50B and the anode penetrating conductor 30B, a mixed material of at least one conductive filler selected from the group consisting of silver filler, copper filler, nickel filler, and carbon filler and a resin may be used as a constituent material of the second wiring layer 50B.

[0133] The constituent materials of the first wiring layer 50A and the second wiring layer 50B are preferably the same at least in terms of type, but may be different from each other.

[0134] When multiple capacitor sections 10 are arranged inside the sealing layer 20, each of the capacitor sections 10 may be provided with a first wiring layer 50A electrically connected to the cathode layer 12 and a second wiring layer 50B electrically connected to the anode plate 11, or at least one of the first wiring layer 50A and the second wiring layer 50B may be provided in common among the multiple capacitor sections 10.

[0135] Examples of materials that can be used to form the via conductors 55 include metal materials containing low-resistance metals such as silver, gold, and copper.

[0136] The via conductor 55 is formed, for example, by plating the inner wall surface of a through hole that penetrates the sealing layer 20 in the thickness direction with the above-mentioned metal material, or by filling it with a conductive paste and then performing a heat treatment.

[0137] The capacitor element of the present invention is not limited to the above-described embodiment, and various applications and modifications can be made within the scope of the present invention with respect to the configuration of the capacitor element, the manufacturing conditions of the capacitor element, and the like.

[0138] The capacitor element of the present invention can be suitably used as a constituent material of a composite electronic component. Such a composite electronic component includes, for example, the capacitor element of the present invention, external electrodes provided on the outer side of the sealing layer of the capacitor element and electrically connected to the anode plate and cathode layer of the capacitor element, and an electronic component connected to the external electrodes.

[0139] In a composite electronic component, the electronic component connected to the external electrode may be a passive element or an active element. Both the passive element and the active element may be connected to the external electrode, or either the passive element or the active element may be connected to the external electrode. Also, a composite of a passive element and an active element may be connected to the external electrode.

[0140] Examples of passive elements include inductors, etc. Examples of active elements include memories, GPUs (Graphical Processing Units), CPUs (Central Processing Units), MPUs (Micro Processing Units), and PMICs (Power Management ICs).

[0141] The capacitor element of the present invention has a sheet-like shape as a whole. Therefore, in a composite electronic component, the capacitor element can be treated like a mounting substrate, and electronic components can be mounted on the capacitor element. Furthermore, by making the electronic components mounted on the capacitor element sheet-like, it is also possible to connect the capacitor element and the electronic components in the thickness direction via through-hole conductors that penetrate each electronic component in the thickness direction. As a result, active elements and passive elements can be configured like a single module.

[0142] For example, a switching regulator can be formed by electrically connecting the capacitor element of the present invention between a voltage regulator including a semiconductor active element and a load to which the converted DC voltage is supplied.

[0143] In a composite electronic component, a circuit layer may be formed on either side of a capacitor matrix sheet on which a plurality of capacitor elements of the present invention are laid out, and the circuit layer may be connected to a passive element or an active element.

[0144] Alternatively, the capacitor element of the present invention may be placed in a cavity provided in a substrate, embedded in resin, and then a circuit layer may be formed on the resin. Another electronic component (a passive element or an active element) may be mounted in another cavity of the same substrate.

[0145] Alternatively, the capacitor element of the present invention may be mounted on a smooth carrier such as a wafer or glass, an outer layer made of resin may be formed, a circuit layer may be formed, and then the capacitor element may be connected to a passive or active element.

[0146] The present specification discloses the following:

[0147] <1> A capacitor element comprising: an anode plate having a porous portion on at least one main surface of a core portion; a dielectric layer provided on a surface of the porous portion; and a cathode layer provided on the surface of the dielectric layer; and a sealing layer provided so as to cover at least one main surface of the capacitor portion, wherein a surface roughness R1 of a first portion of a first side surface of the porous portion exposed at a side edge of the capacitor portion is greater than a surface roughness R2 of a second portion of a second side surface of the porous portion exposed in a recess provided in the main surface of the capacitor portion.

[0148] <2> The capacitor element described in <1>, wherein, as an index of the surface roughness R1 of the first portion on the first side surface of the porous portion, the length L1 along the surface of the first portion is at least 2 times and at most 2.5 times the length L0 of a reference line perpendicular to the thickness direction of the capacitor portion.

[0149] <3> The capacitor element according to <2>, wherein the length L1 along the surface of the first portion is 6 μm or more and 8.5 μm or less.

[0150] <4> The capacitor element according to <2> or <3>, wherein, as an index of the surface roughness R2 of the second portion on the second side surface of the porous portion, the length L2 along the surface of the second portion is 1.8 times or less the length L0 of the reference line.

[0151] <5> The capacitor element according to <4>, wherein the length L2 along the surface of the second portion is 5 μm or less.

[0152] <6> The capacitor element according to any one of <1> to <5>, further comprising a wiring layer provided on at least one main surface of the sealing layer, wherein a surface roughness R3 of a third portion on the surface of the wiring layer is greater than a surface roughness R2 of a second portion on the second side surface of the porous portion.

[0153] <7> The capacitor element according to <6>, wherein a surface roughness R3 of a third portion on the surface of the wiring layer is greater than a surface roughness R1 of a first portion on the first side surface of the porous portion.

[0154] <8> The capacitor element according to <6> or <7>, wherein, as an index of the surface roughness R3 of the third portion on the surface of the wiring layer, the length L3 along the surface of the third portion is 2.7 times or more the length L0 of a reference line perpendicular to the thickness direction of the capacitor portion.

[0155] <9> The capacitor element according to <8>, wherein the length L3 along the surface of the third portion is 10 μm or more and 30 μm or less.

[0156] <10> The capacitor element according to any one of <1> to <9>, further comprising a cathode through conductor provided to penetrate the capacitor section and the sealing layer in a thickness direction and electrically connected to the cathode layer, wherein the recess is a cathode through hole that penetrates the capacitor section in the thickness direction, the cathode through conductor is provided inside the cathode through hole, and an insulating material is filled between the cathode through conductor and a side wall surface of the anode plate exposed in the cathode through hole.

[0157] <11> The capacitor element according to any one of <1> to <10>, wherein the recess is a through groove that penetrates the capacitor section in the thickness direction, the anode plate is divided by the through groove, and the through groove is filled with an insulating material.

[0158] <12> The capacitor element according to any one of <1> to <11>, further comprising an anode through conductor that is provided so as to penetrate the capacitor portion and the sealing layer in a thickness direction and is electrically connected to the anode plate, wherein the anode through conductor is electrically connected to a side wall surface of the anode plate.

[0159] <13> The capacitor element according to any one of <1> to <12>, wherein the cathode layer includes a solid electrolyte layer provided on a surface of the dielectric layer.

[0160] <14> The capacitor element according to any one of <1> to <13>, further comprising an outer insulating layer provided so as to cover the capacitor section and the sealing layer.

[0161] REFERENCE SIGNS LIST 1 capacitor element 10 capacitor portion 11 anode plate 11A core portion 11B porous portion 12 cathode layer 12A solid electrolyte layer 12B conductor layer 13 dielectric layer 20 sealing layer 25 insulating mask layer 30 through conductor 30A cathode through conductor 30B anode through conductor 33 anode connection layer 35A first resin filled portion 35B second resin filled portion 41 cathode through hole (recess) 43 anode through hole 45 through groove (recess) 50 wiring layer 50A first wiring layer 50B second wiring layer 55 via conductor 60 outer insulating layer 65 outer circuit layer RL reference line

Claims

1. A capacitor element comprising: an anode plate having a porous portion on at least one main surface of a core portion; a dielectric layer provided on the surface of the porous portion; and a cathode layer provided on the surface of the dielectric layer; and a sealing layer provided so as to cover at least one main surface of the capacitor portion, wherein a surface roughness R1 of a first portion of a first side surface of the porous portion exposed at a side edge of the capacitor portion is greater than a surface roughness R2 of a second portion of a second side surface of the porous portion exposed in a recess provided in the main surface of the capacitor portion.

2. A capacitor element as described in claim 1, wherein, as an index of the surface roughness R1 of the first portion on the first side of the porous portion, the length L1 along the surface of the first portion is at least 2 times and at most 2.5 times the length L0 of a reference line perpendicular to the thickness direction of the capacitor portion.

3. The capacitor element according to claim 2, wherein the length L1 along the surface of the first portion is not less than 6 μm and not more than 8.5 μm.

4. A capacitor element as described in claim 2 or 3, wherein, as an index of the surface roughness R2 of the second portion on the second side of the porous portion, the length L2 along the surface of the second portion is 1.8 times or less the length L0 of the reference line.

5. The capacitor element according to claim 4, wherein the length L2 along the surface of the second portion is 5 μm or less.

6. A capacitor element according to any one of claims 1 to 5, further comprising a wiring layer provided on at least one main surface of the sealing layer, wherein the surface roughness R3 of a third portion on the surface of the wiring layer is greater than the surface roughness R2 of a second portion on the second side surface of the porous portion.

7. The capacitor element according to claim 6, wherein the surface roughness R3 of the third portion on the surface of the wiring layer is greater than the surface roughness R1 of the first portion on the first side surface of the porous portion.

8. A capacitor element as described in claim 6 or 7, wherein, as an index of the surface roughness R3 of the third portion on the surface of the wiring layer, the length L3 along the surface of the third portion is 2.7 times or more the length L0 of a reference line perpendicular to the thickness direction of the capacitor portion.

9. The capacitor element according to claim 8, wherein the length L3 along the surface of the third portion is 10 μm or more and 30 μm or less.

10. A capacitor element according to any one of claims 1 to 9, further comprising a cathode through conductor that is provided so as to penetrate the capacitor section and the sealing layer in the thickness direction and is electrically connected to the cathode layer, wherein the recess is a cathode through hole that penetrates the capacitor section in the thickness direction, the cathode through conductor is provided inside the cathode through hole, and an insulating material is filled between the cathode through conductor and a side wall surface of the anode plate exposed in the cathode through hole.

11. A capacitor element according to any one of claims 1 to 10, wherein the recess is a through groove that penetrates the capacitor section in the thickness direction, the anode plate is divided by the through groove, and an insulating material is filled in the through groove.

12. A capacitor element according to any one of claims 1 to 11, further comprising an anode through conductor that is provided so as to penetrate the capacitor section and the sealing layer in the thickness direction and is electrically connected to the anode plate, and the anode through conductor is electrically connected to a side wall surface of the anode plate.

13. The capacitor element according to any one of claims 1 to 12, wherein the cathode layer includes a solid electrolyte layer provided on the surface of the dielectric layer.

14. The capacitor element according to any one of claims 1 to 13, further comprising an outer insulating layer provided so as to cover the capacitor section and the sealing layer.

Images