Anode foil for solid electrolytic capacitor, solid electrolytic capacitor, and method for manufacturing anode foil for solid electrolytic capacitor

Abstract

A positive electrode foil (10) for a solid electrolytic capacitor is provided with: a core bar (12); a spongy porous layer (14) provided on the core bar (12); and a spongy through-hole (16) which is provided in a portion of the surface of the core bar (12) and which penetrates the core bar (12).

Description

Technical Field

[0001] This invention relates to anode foil for solid electrolytic capacitors, solid electrolytic capacitors, and a method for manufacturing anode foil for solid electrolytic capacitors. Background Technology

[0002] Patent Document 1 describes an anode substrate obtained by roughening the surface into a sponge-like pit through a through-type tunnel pit formed in a valve-acting metal foil and a cubic pit formed by AC etching.

[0003] Patent document 2 describes a technique for creating tunnel-shaped pits and fine pits in aluminum foil.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 6-168855

[0007] Patent Document 2: Japanese Patent Application Publication No. 10-223484 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] The high capacitance of solid electrolytic capacitors requires an increase in specific surface area based on porosity and the seamless filling of the porous material with conductive polymer. Conventional anode foils are formed by electrolytic etching of rolled aluminum foil from the surface side. To maintain strength, the core is left unetched. Therefore, when the conductive polymer is filled, gas within the voids can only escape to the sides or surface of the porous layer through the connections between the voids. When the surface of the porous layer is covered by the conductive polymer, gas escape becomes difficult, and the filling of the conductive polymer into the deeper parts of the porous layer becomes challenging.

[0010] Furthermore, regarding the through-type tunnel depressions described in Patent Documents 1 and 2, adjacent tunnels tend to connect with each other like cutting lines, which can easily lead to a decrease in the strength of the core. In addition, because the specific surface area expansion rate of the tunnel depressions is small, it is difficult to achieve a balance between specific surface area and strength.

[0011] The present invention was made to solve the above-mentioned problems, and its object is to provide an anode foil for a solid electrolytic capacitor that has an excellent balance between specific surface area and strength as an anode foil as a whole, a solid electrolytic capacitor, and a method for manufacturing the anode foil for a solid electrolytic capacitor.

[0012] Technical solutions for solving the problem

[0013] The anode foil for a solid electrolytic capacitor of the present invention comprises: a core; a sponge-like porous layer disposed on the core; and a sponge-like through hole disposed in a portion of the surface of the core and penetrating the core.

[0014] The solid electrolytic capacitor of the present invention comprises the anode foil for the solid electrolytic capacitor of the present invention.

[0015] The method for manufacturing anode foil for solid electrolytic capacitors of the present invention is a method for manufacturing anode foil for solid electrolytic capacitors having a porous layer on its surface, comprising: a step of etching the surface of a substrate to form a sponge-like porous layer; and a step of etching a portion of the in-plane portion of the core of the substrate to form a sponge-like through hole penetrating the core.

[0016] Invention Effects

[0017] According to the present invention, it is possible to provide an anode foil for a solid electrolytic capacitor that has an excellent balance between specific surface area and strength as an anode foil as a whole, a solid electrolytic capacitor, and a method for manufacturing the anode foil for a solid electrolytic capacitor. Attached Figure Description

[0018] Figure 1 This is a schematic cross-sectional view of the anode foil for a solid electrolytic capacitor according to an embodiment of the present invention.

[0019] Figure 2 This is a perspective view schematically showing the recesses forming sponge-like through holes in the anode foil of a solid electrolytic capacitor according to an embodiment of the present invention.

[0020] Figure 3 A is a schematic diagram showing an example of an initial substrate surface with pits formed by etching. Figure 3 B is a schematic diagram showing an example of a substrate surface where a protective film has been formed after etching. Figure 3 C is a schematic diagram illustrating an example of a substrate surface where pits were re-formed by etching after the protective film was formed. Figure 3 D is a schematic diagram illustrating an example of a substrate surface in which pits are formed by etching without forming a protective film.

[0021] Figure 4 This is a schematic cross-sectional view illustrating the structure of a solid electrolytic capacitor according to an embodiment of the present invention.

[0022] Figure 5 It is Figure 4 The enlarged cross-sectional view shown in section II.

[0023] Figure 6 Observe from the direction of the arrow on line III-III Figure 4A cross-sectional view of a solid electrolytic capacitor. Detailed Implementation

[0024] The following describes the anode foil for a solid electrolytic capacitor, the solid electrolytic capacitor, and the method for manufacturing the anode foil for a solid electrolytic capacitor according to the present invention.

[0025] However, the present invention is not limited to the following structures, and can be applied with appropriate modifications without changing the spirit of the invention. Furthermore, structures obtained by combining two or more of the preferred structures described below are also part of the present invention.

[0026] (Anode foil for solid electrolytic capacitors)

[0027] First, the anode foil for a solid electrolytic capacitor according to embodiments of the present invention will be described.

[0028] Figure 1 This is a schematic cross-sectional view of the anode foil for a solid electrolytic capacitor according to an embodiment of the present invention.

[0029] Figure 1 The solid electrolytic capacitor anode foil 10 shown is an electrode foil for the anode of a solid electrolytic capacitor made of valve-acting metal, and has a core 12, a pair of porous layers 14, and a plurality of through holes 16.

[0030] Examples of metals that can function as valves include individual metals such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, and silicon, or alloys containing these metals. Among these, aluminum or aluminum alloys are preferred.

[0031] The core 12 is a foil-shaped portion located at the center of the anode foil 10 in the thickness direction.

[0032] The thickness of the core 12 is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less, and even more preferably 15 μm or more and 40 μm or less.

[0033] The porous layer 14 is sponge-like, and preferably an etched layer that has been electrolytically etched by hydrochloric acid or the like.

[0034] The porous layers 14 are respectively disposed on the two main surfaces of the core 12, but they can also be disposed on only one main surface of the core 12.

[0035] Regarding the thickness of the porous layer 14, each layer on one side is preferably 5 μm or less and 200 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 20 μm or more and 70 μm or less.

[0036] The through-hole 16 is provided within a portion of the surface of the core 12 and is a sponge-like through-hole penetrating the core 12. In this way, by providing a path through the core 12, a gas venting path can also be formed on the opposite side for the filling of the conductive polymer from the surface of the anode foil 10, thus facilitating gas-liquid exchange. Therefore, the filling (impregnation) of the conductive polymer into the depth of the porous layer 14 is improved, thereby enhancing the capacitance performance of the solid electrolytic capacitor.

[0037] Furthermore, since the through-holes 16 are sponge-like, meaning that the sponge structure penetrates the core 12, metal residues also exist three-dimensionally within the through-holes 16. Therefore, structurally, the through-holes 16 are less likely to connect like cutting lines (which would lessen the strength of the core 12), and they also contribute to the increase in specific surface area. Thus, a balance between specific surface area and strength can be achieved for the anode foil 10 as a whole. Moreover, by providing sponge-like through-holes 16, the expansion ratio of the porous layer 14 can be reduced compared to the case where sponge-like through-holes 16 are not provided in the core 12.

[0038] The sponge-like through holes 16 are dispersedly disposed within the surface of the core rib 12. The area ratio of the through holes 16 within the surface of the core rib 12 is not particularly limited, but a larger ratio improves the impregnation of the conductive polymer; however, if the ratio is too large, it may not adequately ensure the strength of the core rib 12. From this perspective, specifically, the area ratio of the through holes 16 within the surface of the core rib 12 is preferably 10% or more and 90% or less, more preferably 20% or more and 60% or less.

[0039] Furthermore, the proportion of the area occupied by the through-hole 16 within the surface of the core 12 can be calculated, for example, by removing it to the core portion using methods such as mechanical grinding, and by performing image processing on the observation image obtained through scanning electron microscopy (SEM) to create a binary image. This binary image is then analyzed to calculate the proportion (percentage) of the through-hole area relative to the observation area. Since the brightness in the observation image differs significantly between the core portion and the through-hole portion, binarization can distinguish between the two regions.

[0040] Regarding the area occupied by the sponge-like through-holes 16, each through-hole 16 is preferably 0.025 μm. 2 Above and 1μm 2 The following is more preferably 0.05 μm 2 Above and 0.5μm 2 the following.

[0041] Furthermore, regarding the area occupied by the sponge-like through-holes 16, for example, it is possible to analyze the observation images obtained by SEM observation, etc., as described above, and measure the area of ​​at least 50 through-holes, and calculate it by their average value (arithmetic mean).

[0042] While the pit structure constituting the sponge-like through-hole 16 can be the same as the pit structure constituting the porous layer 14, it is preferable to be different.

[0043] In addition, a pit means a single cavity (cluster) of a single shape. As a pit structure, for example, the shape, size (e.g., diameter) of a pit, the continuous state of multiple pits, etc. can be listed.

[0044] exist Figure 1 In this design, the pits 14a constituting the sponge-like porous layer 14 and the pits 16a constituting the sponge-like through-holes 16 are both cubic in shape of the same size, but the size and shape of the pits 14a and 16a are not particularly limited. For example, the shapes of the pits 14a and 16a can also be different; for instance, the pits 14a constituting the porous layer 14 can be cubic, while the pits 16a constituting the through-holes 16 can be spherical. Such spherical pits can be obtained, for example, by chemically dissolving the surface of the pits after forming cubic pits using electrolytic etching. Alternatively, cubic pits can be formed by electrolytic etching with alternating current, as described later.

[0045] Figure 2 This is a perspective view schematically showing the recesses forming sponge-like through holes in the anode foil of a solid electrolytic capacitor according to an embodiment of the present invention.

[0046] In addition, such as Figure 2 As shown, through chemical dissolution following electrolytic etching, the area of ​​the overlapping portion (connected portion) 16b of the adjacent cubic pits 16a of the through hole 16 can be expanded as needed. This further improves the impregnation properties of the conductive polymer.

[0047] (Manufacturing method of anode foil for solid electrolytic capacitors)

[0048] Next, a method for manufacturing the anode foil for a solid electrolytic capacitor according to an embodiment of the present invention will be described.

[0049] The method for manufacturing anode foil for solid electrolytic capacitors according to this embodiment is a method for manufacturing electrode foil for anode of solid electrolytic capacitors having a porous layer on the surface, and is suitable for manufacturing the anode foil for solid electrolytic capacitors according to the above embodiment.

[0050] In the manufacturing method described in this embodiment, the substrate is first prepared.

[0051] As the substrate, a metal foil containing a valve-acting metal is preferred, and the materials mentioned above can be listed as valve-acting metals. As the metal foil, a rolled metal foil is preferred.

[0052] The thickness of the substrate is preferably 15 μm or more and 500 μm or less, more preferably 30 μm or more and 200 μm or less.

[0053] Next, the surface of the substrate is etched to form a sponge-like porous layer. Thus, a sponge-like porous layer is formed on at least one main surface (preferably both main surfaces) of the core. Furthermore, in this specification, unless otherwise specified, "etching" refers to electrolytic etching. Examples of electrolytes used for etching include hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0054] More specifically, a first etching process is performed to etch the surface of the substrate to form sponge-like pits, and a first intermediate process is performed to form a protective film on the surface of the pits formed by the first etching process. The first etching process and the first intermediate process are usually performed alternately multiple times.

[0055] Furthermore, the first etching process is performed by alternating positive and negative currents on the substrate in a first AC etching process. Specifically, for example, a rectangular wave AC current is applied to the substrate. This allows the formation of a sponge-like porous layer composed of cubic pits. Alternatively, a sinusoidal AC current can also be applied to the substrate in the first AC etching process.

[0056] More specifically, when using rectangular wave AC, it's not a simple repetition of the rectangular wave. Instead, a larger amplitude rectangular wave AC is used in the early stages of the etching process, and a smaller amplitude rectangular wave AC is used in the latter half of the etching process. Furthermore, intervals where no current is applied are included during the rectangular wave AC application. By varying the amplitude of this applied current and setting the number and duration of these intervals, the dispersion of the etched pits and the degree of etching progress in the depth direction can be varied, making it easier to obtain the desired etching state. The same applies when using sinusoidal wave AC.

[0057] The first etching process and the first intermediate process for forming the porous layer can be performed in the same way as the conventional etching process and intermediate process for forming a sponge-like porous layer.

[0058] Next, a portion of the in-plane portion of the core of the substrate is etched to form a sponge-like through-hole penetrating the core. As a result, the solid electrolytic capacitor is completed using an anode foil.

[0059] More specifically, a second etching process is performed to etch a portion of the in-plane portion of the core to form sponge-like pits, and a second intermediate process is performed to form a protective film on the surface of the pits formed by the second etching process. The second etching process and the second intermediate process are typically performed alternately multiple times.

[0060] In the first and second intermediate processes, the etched substrate is immersed in a processing solution, such as an aqueous solution of phosphate, thereby forming a film on the surface of the etched substrate as a complex containing phosphate ions and aluminum, which functions as a protective film. If etching continues without intermediate processing, the pits will merge into large pores, potentially reducing the surface area. By forming a protective film through intermediate processing between etching processes, the local etching of already formed pits is suppressed, and the merging of pits is improved (suppressed). Furthermore, by suppressing local etching, the dispersion of pits is improved, and since etching continues in the depth direction in this state, the surface area can be increased. Besides phosphate and aluminum complexes, aluminum hydrates can also be cited as examples of the protective film formed by the first and second intermediate processes.

[0061] The first and second intermediate processes preferably satisfy at least one of the following conditions (1) to (3).

[0062] (1) The number of times the second intermediate processing is less than the number of times the first intermediate processing is performed.

[0063] (2) The time for the second intermediate processing is shorter than that for the first intermediate processing.

[0064] (3) The concentration of the treatment solution used for the second intermediate treatment is less than the concentration of the treatment solution used for the first intermediate treatment.

[0065] Therefore, sponge-like through-holes can be easily formed. To explain in more detail, if there are defects in the protective film or the protective film is thin, these defects and thin film portions become active points and are etched in a concentrated manner, thereby etching into the depth direction of the substrate. In addition, if the number of intermediate processing steps is reduced, the intermediate processing time is shortened, or the concentration of the processing solution used in the intermediate processing is diluted, the uniformity of the protective film deteriorates, and it becomes difficult to form a protective layer deep in the substrate (near the center). That is, the protectiveness of the substrate surface decreases, and selective etching is easy to perform deep in the substrate. Therefore, if at least one of the above conditions (1) to (3) is met, firstly, by the first etching process accompanying the first intermediate processing, a porous layer is formed while the pits are dispersed in the in-plane direction and the depth direction. Then, by the second etching process accompanying the second intermediate processing, a portion in the in-plane is etched from the two main surfaces of the substrate into the depth direction, thereby connecting the pits and easily forming sponge-like through-holes.

[0066] Furthermore, the second etching process is performed by at least one of (4) alternating positive and negative current on the substrate and (5) etching on the substrate with only intermittent positive current, and (4) the second alternating current etching preferably satisfies at least one of the following conditions (4A) and (4B).

[0067] (4A) The absolute value of the negative current is smaller than the absolute value of the positive current.

[0068] (4B) The on-time of negative current is shorter than that of positive current.

[0069] Therefore, it is also possible to easily form sponge-like through holes. To explain in more detail, when a porous layer is formed on the surface of a substrate by alternating current etching, a protective film (e.g., water and film of aluminum) is generally formed when a positive current is applied (on the cathode side of the alternating current), and the substrate (e.g., aluminum) is dissolved when a negative current is applied (on the anode side of the alternating current). At this time, if no negative current is applied, it is difficult to protect the etched porous parts with the protective film so as to etch the unetched parts, that is, it is difficult to disperse the sponge-like pits, so etching is performed locally within the substrate surface. Therefore, in the second etching process, which is used to form sponge-like through holes, by etching with an alternating current waveform with a smaller negative current (the above conditions (4A), (4B)) and / or by etching without applying a negative current (the above condition (5)), it is possible to easily form sponge-like through holes.

[0070] The second AC etching in (4) above can also be performed, for example, by switching on a rectangular AC wave with a bias voltage applied in the direction of the flowing positive current. This allows the formation of a sponge-like through-hole composed of cubic pits. Alternatively, the second AC etching in (4) above can also be performed by switching on a sinusoidal AC wave with a bias voltage applied in the direction of the flowing positive current.

[0071] The etching in (5) above is preferably performed with a waveform similar to a half-wave of a rectangular alternating current. This allows for the formation of sponge-like through-holes composed of cubic pits. Alternatively, the etching in (5) above can also be performed with a waveform similar to a half-wave of a sine alternating current.

[0072] In addition, in the first etching process, which is the first half of the etching process used to form a sponge-like porous layer, the electrostatic capacitance of the solid electrolytic capacitor will decrease if the etching is performed without applying a negative current. Therefore, in the first etching process, it is preferable to alternately apply a positive current and a negative current to the substrate to perform alternating etching as described above to prevent the electrostatic capacitance from decreasing.

[0073] As explained above, in the manufacturing method of this embodiment, a sponge-like porous layer and a sponge-like through-hole can be separately fabricated by controlling the protective film on the pit. The principle is summarized and shown below. Figure 3 A~ Figure 3 D.

[0074] Figure 3 A is a schematic diagram illustrating an example of an initial substrate surface where pits have been formed by etching. Figure 3 B is a schematic diagram showing an example of a substrate surface where a protective film has been formed after etching. Figure 3 C is a schematic diagram illustrating an example of a substrate surface where pits were re-formed by etching after the protective film was formed. Figure 3 D is a schematic diagram illustrating an example of a substrate surface in which pits are formed by etching without forming a protective film.

[0075] If cubical pits 20 are formed by etching, highly active sites 21 are generated in deeper areas (see reference). Figure 3 (A), but if the surface of the formed pit 20 is fully covered by the protective film 22 (see A). Figure 3 (B), then through subsequent etching, pits 20 are dispersedly formed within the substrate surface (see reference). Figure 3 (C). On the other hand, if the surface of the pit 20 is not covered by the protective film 22, subsequent etching will proceed in the depth direction of the substrate, resulting in the local formation of the pit 20 within the substrate surface (see C). Figure 3 (D).

[0076] That is, in the manufacturing method according to this embodiment described above, basically, in the porous layer formation step, etching is performed while a protective film is sufficiently formed, thereby forming pits dispersedly within the substrate surface. In contrast, in the through-hole formation step, etching is performed while a protective film is not sufficiently formed (including cases where no protective film is formed), thereby forming pits locally within the substrate surface and allowing them to grow in the depth direction. As a result, after forming a sponge-like porous layer on the surface of the substrate, it is possible to easily and continuously form a sponge-like through-hole penetrating a portion of the core within the surface.

[0077] (Solid electrolytic capacitor)

[0078] Next, the solid electrolytic capacitor according to the embodiments of the present invention will be described.

[0079] Figure 4 This is a schematic cross-sectional view illustrating the structure of a solid electrolytic capacitor according to an embodiment of the present invention. Figure 5 It is Figure 4 The enlarged cross-sectional view shown in section II. Figure 6 Observe from the direction of the arrow on line III-III Figure 4 A cross-sectional view of a solid electrolytic capacitor. Figure 4 as well as Figure 6 In the diagram, L represents the length direction of the insulating resin body (described later), T represents the height direction, and W represents the width direction. The height direction T is orthogonal to the length direction L, and the width direction W is orthogonal to both the length direction L and the height direction T.

[0080] Figures 4-6 The solid electrolytic capacitor 100 shown has a generally cuboid shape. In this embodiment, the external dimensions of the solid electrolytic capacitor 100 are, for example, 7.3 mm in the length direction L, 4.3 mm in the width direction W, and 1.9 mm in the height direction T.

[0081] The solid electrolytic capacitor 100 comprises three or more capacitor elements 180, an insulating resin body 110, a first terminal 120, and a second terminal 130.

[0082] Specifically, three or more capacitor elements 180 are disposed inside the insulating resin body 110. The insulating resin body 110 has a generally cuboid shape. The insulating resin body 110 has a first main surface 110a and a second main surface 110b opposite each other in the height direction T, a first side surface 110c and a second side surface 110d opposite each other in the width direction W, and a first end surface 110e and a second end surface 110f opposite each other in the length direction L.

[0083] As described above, the insulating resin body 110 has a generally rectangular parallelepiped shape, but it may also have rounded corners and edges. The corners are the parts where three faces of the insulating resin body 110 intersect, and the edges are the parts where two faces of the insulating resin body 110 intersect. At least one of the following surfaces may also have irregularities or protrusions: the first main surface 110a, the second main surface 110b, the first side surface 110c, the second side surface 110d, the first end surface 110e, and the second end surface 110f.

[0084] The insulating resin body 110 is composed of insulating resins such as epoxy resin, in which glass or silicon oxides are dispersed and mixed as fillers.

[0085] Each of three or more capacitor elements 180 includes an anode portion 140, a dielectric layer 150, and a cathode portion 160. The three or more capacitor elements 180 are stacked on top of each other in the height direction T.

[0086] The anode portion 140 includes the anode foil 10 for the solid electrolytic capacitor described above.

[0087] A dielectric layer 150 is disposed on the outer surface of the anode foil 10. In this embodiment, the dielectric layer 150 is composed of an aluminum oxide. Specifically, the dielectric layer 150 is composed of an aluminum oxide formed by anodizing the outer surface of the anode foil 10.

[0088] The cathode portion 160 has a solid electrolyte layer 161 and a current collector layer. The solid electrolyte layer 161 is disposed on a portion of the outer surface of the dielectric layer 150. On the side opposite to the cathode portion 160, on the outer surface of the dielectric layer 150 near the second end face 110f of the anode foil 10, the solid electrolyte layer 161 is not disposed on its outer surface. In this portion of the dielectric layer 150, the portion adjacent to the portion where the solid electrolyte layer 161 is disposed is covered by an insulating resin layer 151, described later.

[0089] like Figure 5 As shown, the solid electrolyte layer 161 is configured to fill multiple recesses of the anode foil 10. However, as long as the aforementioned portion of the outer surface of the dielectric layer 150 is covered by the solid electrolyte layer 161, there may also be recesses of the anode foil 10 that are not filled by the solid electrolyte layer 161. The solid electrolyte layer 161 is, for example, composed of a polymer containing a conductive polymer such as poly(3,4-ethylenedioxythiophene).

[0090] A current collector layer is disposed on the outer surface of the solid electrolyte layer 161. In this embodiment, the current collector layer is composed of a first current collector layer 162 disposed on the outer surface of the solid electrolyte layer 161 and a second integrated layer 163 disposed on the outer surface of the first current collector layer 162. The first current collector layer 162 contains carbon. The second integrated layer 163 contains silver.

[0091] As described above, in the dielectric layer 150 located on the side opposite to the cathode portion 160 and in which no solid electrolyte layer 161 is provided, the portion adjacent to the portion in which the solid electrolyte layer 161 is provided is covered with an insulating resin layer 151 that is different from the insulating resin body 110.

[0092] like Figure 5 As shown, the insulating resin layer 151, in the portion adjacent to the portion of the anode foil 10 where the solid electrolyte layer 161 is provided, is configured with a plurality of recesses filling the outer surface. The insulating resin layer 151 comprises an insulating resin such as polyimide resin or polyamide-imide resin.

[0093] like Figure 4 as well as Figure 6As shown, capacitor elements 180 adjacent to each other in the stacking direction are electrically connected to each other via a connecting conductor layer 190. The width of the connecting conductor layer 190 in the width direction W is the same as the width of the anode foil 10 in the width direction W. The connecting conductor layer 190 contains silver.

[0094] In the stacking direction, the anode foils 10 of adjacent capacitor elements 180 are electrically connected to each other by resistance welding or the like in the second end face 110f.

[0095] The first terminal 120 is a lead frame. The first terminal 120 is electrically connected to the cathode portion 160 of each of three or more capacitor elements 180 and is led out to the outside of the insulating resin body 110. In the first terminal 120, the portion located inside the insulating resin body 110 faces the current collector layer of each of two capacitor elements 180 adjacent to each other in the stacking direction, and is connected to the current collector layer respectively via a connecting conductor layer 190. In the first terminal 120, the portion located outside the insulating resin body 110 is bent along the first end face 110e and the second main face 110b of the insulating resin body 110.

[0096] The second terminal 130 is a lead frame. The second terminal 130 is electrically connected to the anode portion 140 of each of three or more capacitor elements 180 and is led out to the outside of the insulating resin body 110. In the second terminal 130, the portion located inside the insulating resin body 110 is clamped by the ends of the anode foils 10 of two capacitor elements 180 adjacent to each other in the stacking direction near the second end face 110f, and is respectively connected to the anode foils 10 by resistance welding or the like. In the second terminal 130, the portion located outside the insulating resin body 110 is bent along the second end face 110f and the second main face 110b of the insulating resin body 110.

[0097] Furthermore, in the above embodiment, the case where a pair of lead frames extending from a pair of end faces are used as a pair of terminals (external electrodes) electrically connected to the anode and cathode portions of each capacitor element has been described. However, in the solid electrolytic capacitor of the present invention, a pair of electrode layers formed on a pair of end faces may also be used as a pair of terminals (external electrodes).

[0098] Furthermore, while the above embodiments described a chip-type solid electrolytic capacitor, the solid electrolytic capacitor of the present invention can also be used, for example, embedded in a packaging substrate included in a semiconductor device. Here, as a semiconductor device, for example, a semiconductor composite device in which a voltage regulator (voltage control device) and a load are mounted on the packaging substrate can be cited.

[0099] The following information is disclosed in this specification.

[0100] <1>

[0101] An anode foil for a solid electrolytic capacitor, comprising:

[0102] Core;

[0103] A sponge-like porous layer is disposed on the core; and

[0104] A sponge-like through hole is provided in a portion of the surface of the core and penetrates the core.

[0105] <2>

[0106] According to <1>, the anode foil for a solid electrolytic capacitor, wherein,

[0107] The pit structure constituting the through hole is different from the pit structure constituting the porous layer.

[0108] <3>

[0109] A solid electrolytic capacitor comprising the anode foil for a solid electrolytic capacitor as described in <1> or <2>.

[0110] <4>

[0111] A method for manufacturing anode foil for solid electrolytic capacitors involves manufacturing anode foil for solid electrolytic capacitors with a porous layer on its surface, wherein...

[0112] Include:

[0113] The process of etching the surface of a substrate to form a sponge-like porous layer; and

[0114] The process of etching a portion of the in-plane portion of the core of the substrate to form a sponge-like through-hole penetrating the core.

[0115] <5>

[0116] According to the manufacturing method of anode foil for solid electrolytic capacitors described in <4>, in which,

[0117] The process of forming the porous layer includes: a first etching process of etching the surface of the substrate to form sponge-like pits; and a first intermediate process of forming a protective film on the surface of the pits formed by the first etching process.

[0118] The process of forming the through hole includes: a second etching process of etching a portion of the in-plane of the core to form a sponge-like pit; and a second intermediate process of forming a protective film on the surface of the pit formed by the second etching process.

[0119] The method for manufacturing the anode foil for the solid electrolytic capacitor satisfies at least one of the following conditions (1) to (3):

[0120] (1) The number of times the second intermediate processing is performed in the process of forming the through hole is less than the number of times the first intermediate processing is performed in the process of forming the porous layer;

[0121] (2) The time for the second intermediate treatment performed in the process of forming the through-hole is shorter than the time for the first intermediate treatment performed in the process of forming the porous layer; and

[0122] (3) The concentration of the treatment liquid used in the second intermediate treatment in the process of forming the through hole is less than the concentration of the treatment liquid used in the first intermediate treatment in the process of forming the porous layer.

[0123] <6>

[0124] According to the manufacturing method of the anode foil for solid electrolytic capacitors described in <4> or <5>, wherein,

[0125] The process of forming the porous layer includes a first etching process of etching the surface of the substrate to form sponge-like pits.

[0126] The process of forming the through hole includes a second etching process that etches a portion of the in-plane portion of the core to form a sponge-like pit.

[0127] The first etching process is performed by alternating positive and negative currents during a first AC etching process on the substrate.

[0128] The second etching process is performed by at least one of (4) a second AC etching process in which a positive current and a negative current are alternately applied to the substrate, and (5) an etching process in which a positive current is applied to the substrate only intermittently.

[0129] The second AC etching in (4) satisfies at least one of the following conditions (4A) and (4B):

[0130] (4A) The absolute value of the negative current is smaller than the absolute value of the positive current; and

[0131] (4B) The on-time of the negative current is shorter than that of the positive current.

[0132] Explanation of reference numerals in the attached figures

[0133] 10. Anode foil for solid electrolytic capacitors;

[0134] 12-core bone;

[0135] 14. Porous layers;

[0136] 14a The pits that form the porous layer;

[0137] 16 Through holes;

[0138] 16a The recess that forms the through hole;

[0139] 16b The overlapping portion of the pits;

[0140] 20. Dents;

[0141] 21. Active site;

[0142] 22. Protective film;

[0143] 100 Solid electrolytic capacitor;

[0144] 110 Insulating resin body;

[0145] 110a First main face;

[0146] 110b Second main face;

[0147] 110c First side view;

[0148] 110d, second side view;

[0149] 110e First end face;

[0150] 110f Second end face;

[0151] 120 Terminal 1;

[0152] 130 Terminal 2;

[0153] 140 Anode section;

[0154] 150 dielectric layer;

[0155] 151 Insulating resin layer;

[0156] 160 Cathode section;

[0157] 161 Solid electrolyte layer;

[0158] 162 First collector layer;

[0159] 163 Second Integral Layer;

[0160] 180 Capacitor Components;

[0161] 190 Connecting conductor layer.

Claims

1. An anode foil for a solid electrolytic capacitor, comprising: Core; A sponge-like porous layer is disposed on the core; and A sponge-like through hole is provided in a portion of the surface of the core and penetrates the core.

2. The anode foil for a solid electrolytic capacitor according to claim 1, wherein, The pit structure constituting the through hole is different from the pit structure constituting the porous layer.

3. A solid electrolytic capacitor comprising the anode foil for a solid electrolytic capacitor as described in claim 1 or 2.

4. A method for manufacturing an anode foil for a solid electrolytic capacitor, comprising a method for manufacturing an anode foil for a solid electrolytic capacitor having a porous layer on its surface, wherein, Include: The process of etching the surface of a substrate to form a sponge-like porous layer; and The process of etching a portion of the in-plane portion of the core of the substrate to form a sponge-like through-hole penetrating the core.

5. The method for manufacturing anode foil for a solid electrolytic capacitor according to claim 4, wherein, The process of forming the porous layer includes: a first etching process of etching the surface of the substrate to form sponge-like pits; and a first intermediate process of forming a protective film on the surface of the pits formed by the first etching process. The process of forming the through hole includes: a second etching process of etching a portion of the in-plane of the core to form a sponge-like pit; and a second intermediate process of forming a protective film on the surface of the pit formed by the second etching process. The method for manufacturing the anode foil for the solid electrolytic capacitor satisfies at least one of the following conditions (1) to (3): (1) The number of times the second intermediate processing is performed in the process of forming the through hole is less than the number of times the first intermediate processing is performed in the process of forming the porous layer; (2) The time of the second intermediate treatment performed in the process of forming the through hole is shorter than the time of the first intermediate treatment performed in the process of forming the porous layer; and (3) The concentration of the treatment liquid used in the second intermediate treatment in the process of forming the through hole is less than the concentration of the treatment liquid used in the first intermediate treatment in the process of forming the porous layer.

6. The method for manufacturing anode foil for a solid electrolytic capacitor according to claim 4 or 5, wherein, The process of forming the porous layer includes a first etching process of etching the surface of the substrate to form sponge-like pits. The process of forming the through hole includes a second etching process that etches a portion of the in-plane portion of the core to form a sponge-like pit. The first etching process is performed by alternating positive and negative currents during a first AC etching process on the substrate. The second etching process is performed by at least one of (4) a second AC etching process in which a positive current and a negative current are alternately applied to the substrate, and (5) an etching process in which a positive current is applied to the substrate only intermittently. The second AC etching in (4) satisfies at least one of the following conditions (4A) and (4B): (4A) The absolute value of the negative current is smaller than the absolute value of the positive current; and (4B) The on-time of the negative current is shorter than that of the positive current.

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