Solid electrolytic capacitor

Abstract

A solid electrolytic capacitor is provided with: a sheet laminate formed by alternately laminating a plurality of flat film-like capacitor elements in which a dielectric layer and a solid electrolyte layer are formed in this order on the surface of a flat film-like anode electrode foil, and a plurality of flat film-like cathode electrode foils, the flat-film-shaped electrode foil for the anode has a porous part at a given depth from the surface of the flat-film-shaped electrode foil for the anode. A first metal portion formed at an end portion of the anode electrode foil and an end portion of the solid electrolyte layer in the sheet laminate; and an insulating resin that seals the sheet laminate. A first pore diameter of the first metal portion is larger than a second pore diameter of the porous portion of the anode electrode foil.

Description

Technical Field

[0001] The present invention relates to a solid electrolytic capacitor including a laminated body in which a plurality of capacitor elements and a plurality of cathode electrodes are alternately laminated. Background Art

[0002] Patent Document 1 describes a method for manufacturing a solid electrolytic capacitor and a solid electrolytic capacitor. The solid electrolytic capacitor described in Patent Document 1 includes a plurality of flat film capacitor elements and a plurality of metal foils (cathodes). The flat film capacitor element includes a foil-shaped valve metal substrate, a porous portion formed on the valve metal substrate and a dielectric layer on the surface, and a solid electrolyte layer formed on the surface of the dielectric layer.

[0003] More specifically, the following structure is provided. An insulating resin (masking agent) is impregnated in the porous portion of the capacitor element of Patent Document 1. Furthermore, an insulating adhesive is formed in the insulating resin in a frame shape. Moreover, a solid electrolyte layer is formed in the frame of the insulating adhesive. Flat film-shaped capacitor elements and metal foils are alternately stacked to form an element stack. Furthermore, an external electrode in the solid electrolytic capacitor is formed at the end of the element stack using a conductive paste and a Ni / Sn plating.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-79866 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] The solid electrolytic capacitor in Patent Document 1 has a certain degree of airtightness. That is, during MSL reflow soldering, the moisture that has penetrated into the interior may vaporize, causing a sharp rise in internal pressure. As a result, cracks may sometimes form inside the solid electrolytic capacitor and reach the end of the element stack. If such cracks form during the manufacturing process, the Ni / Sn plating may penetrate into the cracks, which may cause LC failure in terms of long-term reliability.

[0009] Therefore, an object of the present invention is to provide a solid electrolytic capacitor that can suppress the occurrence of cracks and achieve high reliability.

[0010] Technical solutions to solve problems

[0011] The solid electrolytic capacitor of the present invention comprises: a sheet laminate formed by alternately laminating a plurality of flat film capacitor elements and a plurality of flat film cathode electrode foils, wherein the flat film capacitor element has a dielectric layer and a solid electrolyte layer formed in sequence on the surface of a flat film anode electrode foil, and the flat film anode electrode foil has a porous portion at a given depth from the surface; a first metal portion formed at the end of the anode electrode foil and the end of the solid electrolyte layer in the sheet laminate; and an insulating resin for sealing the sheet laminate. The first pore diameter of the first metal portion is larger than the second pore diameter of the porous portion of the anode electrode foil.

[0012] With this structure, even if gas is generated due to vaporization of moisture contained in the solid electrolytic capacitor, the gas can be easily discharged to the first metal portion. That is, the increase in the internal pressure of the solid electrolytic capacitor can be suppressed. The generation of cracks inside the solid electrolytic capacitor can be suppressed.

[0013] Effects of the Invention

[0014] According to the present invention, it is possible to provide a solid electrolytic capacitor that can suppress the occurrence of cracks and achieve high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a side cross-sectional view showing the structure of the solid electrolytic capacitor according to the first embodiment.

[0016] Figure 2 (A) is a side cross-sectional view showing the structure of a group of a capacitor element and a cathode electrode before singulation. Figure 2 (B) is a side cross-sectional view showing the structure of the capacitor element before singulation. Figure 2 (C) is a side cross-sectional view showing the structure of a group of a capacitor element and a cathode electrode after being singulated.

[0017] Figure 3 (A) Figure 3 (B) is a side cross-sectional view showing a schematic structure of a solid electrolytic capacitor.

[0018] Figure 4 This is a perspective view showing the outline of a solid electrolytic capacitor.

[0019] Figure 5 FIG. 2 is a diagram schematically showing the flow of gas generated in a solid electrolytic capacitor.

[0020] Figure 6 This is a flowchart showing an example of a schematic flow of a method for manufacturing a solid electrolytic capacitor according to the present embodiment.

[0021] Figure 7This is a flowchart showing an example of a process for forming a capacitor element sheet.

[0022] Figure 8 (A) is an external perspective view showing the shape of the anode electrode of the capacitor element before singulation. Figure 8 (B) is an external perspective view showing the shape of the capacitor element before being singulated.

[0023] Fig. 9 This is a diagram showing the appearance of multiple capacitor elements.

[0024] Fig.10 It is an external perspective view showing the shape of the cathode electrode before being singulated.

[0025] Fig.11 This is a flowchart showing an example of a process for forming a sheet laminate.

[0026] Fig.12 (A) Fig.12 (B) is an external perspective view showing a state where partition walls are formed on the capacitor element sheet.

[0027] Fig.13 (A) Fig.13 (B) is an external perspective view showing a state where the second partition wall and the first adhesive are formed on the capacitor element sheet.

[0028] Fig.14 (A) Fig.14 (B) is an exploded perspective view showing a state where the capacitor element sheet and the cathode electrode sheet are stacked.

[0029] Fig.15 (A) is an exploded perspective view showing a stacked state of a plurality of capacitor element sheets and cathode electrode sheets, Fig.15 (B) is an external perspective view showing a stacked state of a plurality of capacitor element sheets and cathode electrode sheets.

[0030] Fig.16 This is a flowchart showing an example of a process of forming the first metal portion and the second metal portion.

[0031] Fig.17 It is a side cross-sectional view showing a schematic structure of a solid electrolytic capacitor according to a second embodiment.

[0032] Fig.18 It is a side cross-sectional view showing a schematic structure of a solid electrolytic capacitor in a third embodiment.

[0033] Fig.19 It is a side cross-sectional view showing a schematic structure of a solid electrolytic capacitor in a fourth embodiment. DETAILED DESCRIPTION

[0034] [First embodiment]

[0035] A solid electrolytic capacitor according to a first embodiment of the present invention and a method for manufacturing the solid electrolytic capacitor will be described with reference to the drawings.

[0036] (Description of Schematic Structure of Solid Electrolytic Capacitor 1)

[0037] First, the structure of a solid electrolytic capacitor according to an embodiment of the present invention will be described. Figure 1 1 is a side cross-sectional view showing the structure of the solid electrolytic capacitor according to the first embodiment. Figure 1 In order to make the figure easier to see, only the insulating resin and the external electrodes are hatched. Figure 2 (A) is a side cross-sectional view showing the structure of a group of a capacitor element and a cathode electrode before singulation. Figure 2 (B) is a side cross-sectional view showing the structure of the capacitor element before being singulated. Figure 2 (C) is a side cross-sectional view showing the structure of a group of a capacitor element and a cathode electrode after being singulated.

[0038] like Figure 1 , Figure 2 (A) Figure 2 (B) Figure 2 As shown in (C), the solid electrolytic capacitor 1 includes a capacitor element laminate 100, an insulating resin 50, metal films 61, 62, and external terminal electrodes 71, 72. The capacitor element laminate 100 includes a plurality of flat film capacitor elements 10 and a plurality of flat film cathode electrodes 20. Figure 1 In the figure, the number of flat film capacitor elements 10 and cathode electrodes (number of sheets) is 4, but it is not limited to this. In addition, the cathode electrode 20 corresponds to the "cathode electrode foil" in the present invention. In addition, the metal films 61 and 62 correspond to the "first metal part" in the present invention, and the external terminal electrode 71 corresponds to the "second metal part" in the present invention. The metal film 61 becomes the collector electrode on the anode side of the solid electrolytic capacitor 1, and the metal film 62 becomes the collector electrode on the cathode side of the solid electrolytic capacitor 1.

[0039] like Figure 1 As shown, the solid electrolytic capacitor 1 includes a first main surface 101 and a second main surface 102. The first main surface 101 and the second main surface 102 face each other. The second main surface 102 serves as a mounting surface side of the solid electrolytic capacitor 1.

[0040] like Figure 2As shown in FIG. 2 (B), the capacitor element 10 includes a flat film-shaped anode electrode 11 , a dielectric layer 12 , and a CP layer (solid electrolyte layer) 13 .

[0041] Although in Figure 2 (A) Figure 2 (B) Figure 2 Although the detailed structure is omitted in (C), the anode electrode 11 has many holes. In other words, the anode electrode 11 is porous (porous body (porous part)). The thickness ratio of the porous part and the core part on one side of the anode electrode 11 and the porous part on the other side is about 1:1:1. The dielectric layer 12 covers the outer surface of the anode electrode 11. Figure 2 (A) Figure 2 (B) Figure 2 In (C), the detailed structure of the anode electrode 11 is omitted, so the dielectric layer 12 is schematically illustrated as covering the macroscopic surface of the anode electrode 11. In fact, the dielectric layer 12 not only covers the macroscopic surface of the anode electrode 11, but also covers the surfaces of many holes of the anode electrode 11. In addition, the anode electrode 11 corresponds to the "anode electrode foil" in the present invention.

[0042] The CP layer 13 covers the surface of the dielectric layer 12. The CP layer 13 is formed inside the frame-shaped first partition wall 14. The first partition wall 14 has insulating properties. The formation area of ​​the CP layer 13 is limited by the first partition wall 14. In addition, in the first embodiment, as described in the manufacturing method described later, after the first partition wall 14 is formed in a frame shape, the CP layer 13 is formed inside the first partition wall 14. However, for example, in the case where the capacitor element 10 is manufactured in a monolithic state from the beginning, according to the manufacturing method of the capacitor element 10, the first partition wall 14 may not be formed in a frame shape. That is, the first partition wall 14 may be formed on one side or on two sides having an angle. Furthermore, it may also be a structure formed on two sides opposite to each other when viewed from above.

[0043] The CP layer 13 has a stacked structure of an inner CP layer (inner solid electrolyte layer) 131 and an outer CP layer (outer solid electrolyte layer) 132. The inner CP layer 131 is formed on the surface of the dielectric layer 12, and the outer CP layer 132 is formed on the surface of the inner CP layer 131.

[0044] The plurality of capacitor elements 10 and the plurality of cathode electrodes 20 are alternately stacked so that their respective flat film surfaces become parallel and overlap each other in a plan view.

[0045] A second partition wall 30 and a first adhesive 40 are disposed between adjacent capacitor elements 10 and cathode electrodes 20. The second partition wall 30 has insulating properties and adhesive properties, and the first adhesive 40 has conductive properties.

[0046] The second partition wall 30 is formed in a frame shape along the outer periphery of the surface of the capacitor element 10 where the CP layer 13 and the cathode electrode 20 face each other. Figure 2 As shown in (B), the second partition wall 30 is formed so as to overlap with the first partition wall 14. In addition, the second partition wall 30 is made of an insulating material such as an insulating resin.

[0047] The first adhesive 40 is disposed inside the frame defined by the second partition walls 30 . The adjacent capacitor elements 10 and cathode electrodes 20 are bonded to each other by the first adhesive 40 .

[0048] In such a stacked state, the first ends 10E1 of the plurality of capacitor elements 10 are in the same position when viewed from the side. Similarly, the second ends 10E2 of the plurality of capacitor elements 10 are in the same position when viewed from the side. Furthermore, the first ends 20E1 of the plurality of cathode electrodes 20 are in the same position when viewed from the side. Similarly, the second ends 20E2 of the plurality of cathode electrodes 20 are in the same position when viewed from the side. However, the so-called same position also includes the following situation, that is, including unexpected deviations during processing, etc., so that it is not strictly the same position.

[0049] The first ends 10E1 of the capacitor elements 10 and the second ends 20E2 of the cathode electrodes 20 are arranged on the first end side of the capacitor element stack 100. The first ends 10E1 of the capacitor elements 10 protrude outward from the second ends 20E2 of the cathode electrodes 20.

[0050] Second ends 10E2 of capacitor elements 10 and first ends 20E1 of cathode electrodes 20 are arranged on the second end side of capacitor element stack 100. First ends 20E1 of cathode electrodes 20 protrude outward from second ends 10E2 of capacitor elements 10.

[0051] With such a structure, capacitor element laminate 100 is realized.

[0052] In addition, in the above-mentioned structure, the structure having the first adhesive 40 is described as an example. However, the CP layer 13 may be formed thicker or a CP layer (solid electrolyte layer) containing a binder may be formed instead of the first adhesive 40. Even when the first adhesive 40 is omitted in this way, a structure in which the capacitor element 10 and the cathode electrode 20 are bonded can be realized.

[0053] The capacitor element stack 100 is sealed with insulating resin 50 . More specifically, the capacitor element stack 100 is covered with insulating resin 50 except for the first ends 10E1 of the capacitor elements 10 (the first ends 10E1 of the anode electrodes 11 ) and the first ends 20E1 of the cathode electrodes 20 .

[0054] The metal film 61 covers the first end 10E1 of the anode electrode 11 and the outer surface of the first end 10E1 side of the insulating resin 50. That is, the metal film 61 serves as a collector electrode on the anode side connected to the first end 10E1 side of the anode electrode 11 of the plurality of capacitor elements 10. Furthermore, the external terminal electrode 71 is formed so as to abut against the metal film 61.

[0055] Similarly, the metal film 62 covers the first end 20E1 of the cathode electrode 20 and the outer surface of the first end 20E1 side of the insulating resin 50. That is, the metal film 62 becomes a collector electrode on the cathode side connected to the first end 20E1 side of the cathode electrode 20 of the plurality of capacitor elements 10. Furthermore, the external terminal electrode 72 is formed to abut against the metal film 62.

[0056] With the above-described structure, the solid electrolytic capacitor 1 is realized.

[0057] (Detailed description of the structure of the external electrode)

[0058] Next, use Figure 3 (A) Figure 3 (B) Figure 4 , Figure 5 , the detailed structure of the metal films 61 , 62 and the external terminal electrodes 71 , 72 will be described. Figure 3 (A) is a diagram showing an overview of the metal film 61 formed on the first end 10E1 side of the anode electrode 11 and the metal film 62 formed on the first end 20E1 side of the cathode electrode 20. Figure 3 (B) is shown in Figure 3 FIG. 7 is a diagram schematically showing how the external terminal electrodes 71 and 72 are formed in the structure of FIG. 7 (A). Figure 4 1 is a perspective view showing the outline of the capacitor element laminate 100 in which the external terminal electrodes 71 and 72 are formed. Figure 3 (A) Figure 3 (B) Figure 4 In order to make the explanation easier to understand, each structure is shown in an enlarged and exaggerated manner.

[0059] like Figure 3 As shown in (A), the metal film 61 is formed by spraying metal on the first end 10E1 of the anode electrode 11 and the outer surface of the first end 10E1 side of the insulating resin 50. Similarly, the metal film 62 is formed by spraying metal on the first end 20E1 of the cathode electrode 20 and the outer surface of the first end 20E1 side of the insulating resin 50.

[0060] Then, if Figure 3 (B) Figure 4As shown, the external terminal electrode 71 is formed to abut against the metal film 61. At this time, the external terminal electrode 71 covers a portion of the mounting surface side (the second main surface 102 side of the capacitor element laminate 100) of the metal film 61. In addition, the external terminal electrode 71 opens the surface side of the metal film 61 that is opposite to the mounting surface. In other words, the external terminal electrode 71 is formed to have an opening 751 on the first main surface 101 side.

[0061] In addition, if Figure 3 (B) Figure 4 As shown, the external terminal electrode 72 is formed to abut against the metal film 62. At this time, the external terminal electrode 72 covers a portion of the mounting surface side (the second main surface 102 side of the capacitor element laminate 100) of the metal film 62. In addition, the external terminal electrode 72 opens the surface side of the metal film 61 that faces the mounting surface. In other words, the external terminal electrode 72 is formed to have an opening 752 on the first main surface 101 side.

[0062] Here, the detailed structure of the metal films 61 and 62 is described. The first pore diameter D1 of the metal films 61 and 62 is preferably larger than the second pore diameter D2 of the porous portion of the anode electrode 11. In this case, the first pore diameter D1 is the average pore diameter of the metal films 61 and 62, and the second pore diameter D2 is the average pore diameter of the anode electrode 11.

[0063] The law of conservation of mass can be applied to the relationship between the first pore diameter D1 and the second pore diameter D2. In other words, the following law (continuity equation) can be applied, that is, the mass flow rate of the guided fluid always becomes constant in any cross section. That is, the gas generated in the anode electrode 11 is ejected from the anode electrode 11 toward the metal films 61 and 62.

[0064] More specifically, since the first pore diameter D1 of the metal films 61 and 62 is larger than the second pore diameter D2 of the anode electrode 11, the gas generated in the anode electrode 11 can easily flow from the anode electrode 11 to the metal films 61 and 62 (see Figure 5 ). As described above, the external terminal electrode 71 is formed to have the opening 751 on the first main surface 101 side, so the gas flows in the direction of the opening 751. Similarly, the external terminal electrode 72 is formed to have the opening 752 on the first main surface 101 side. Therefore, the gas flows in the direction of the opening 752.

[0065] With such a structure, for example, the gas generated in the anode electrode 11 during MSL reflow does not stay inside the solid electrolytic capacitor 1 but is released to the outside. That is, separation and cracking caused by the gas generated in the solid electrolytic capacitor 1 can be suppressed.

[0066] In addition, this relationship can be easily achieved by forming the metal film 61 by sputtering.

[0067] (Method for Manufacturing Solid Electrolytic Capacitor 1)

[0068] The solid electrolytic capacitor 1 having the above-described structure is manufactured, for example, as follows. Figure 6 This is a flowchart showing an example of a schematic flow of a method for manufacturing a solid electrolytic capacitor according to the present embodiment.

[0069] Forming capacitor element sheets ( Figure 6 : S11). A plurality of capacitor elements 10 forming different solid electrolytic capacitors 1 are arranged on the capacitor element sheet.

[0070] Next, the capacitor element sheet and the cathode electrode sheet are stacked with the second partition wall 30 and the first adhesive 40 interposed therebetween, thereby forming a sheet stack ( Figure 6 :S12). In addition, a plurality of cathode electrodes 20 forming different solid electrolytic capacitors 1 are formed in an arranged state on the cathode electrode sheet. Thus, a structure in which a plurality of capacitor element stacks 100 are arranged on a plane is formed. In other words, the so-called sheet stack is a sheet stack in which a plurality of capacitor element stacks 100 are arranged on a plane.

[0071] Next, the sheet stack is sealed with an insulating resin 50 ( Figure 6 : S13). At this time, the sheet laminate is provided with a through hole penetrating from the upper surface to the lower surface of the sheet laminate, and resin sealing is performed by compression molding, which will be described in detail later.

[0072] The sealing with insulating resin 50 is performed in a state where the solid electrolytic capacitor 1 is in a plurality of pieces before being separated into pieces (a state where a plurality of solid electrolytic capacitors 1 are arranged).

[0073] Next, the sheet stack sealed with the insulating resin 50 is cut into individual pieces ( Figure 6 :S14). Specifically, along the following Fig.12The solid electrolytic capacitor 1 is cut along the cutting lines E11, E12, S11, and S12 shown in (B). Thus, a plurality of solid electrolytic capacitors 1 (referred to as the main body of the solid electrolytic capacitor 1) are formed in a state where no external electrodes are formed. Then, the main body of the solid electrolytic capacitor 1 is secondary sealed with an insulating resin 50. More specifically, the side surfaces of the main body of the solid electrolytic capacitor 1 (the surfaces cut at the cutting lines S11 and S12 (side surfaces different from the upper surface, the lower surface, and the end surfaces where the anode electrode 11 and the cathode electrode 20 are exposed)) are covered by the secondary sealing with the insulating resin 50. Thus, the anode electrode 11 and the cathode electrode 20 that are not necessarily exposed during singulation are covered with the insulating resin 50.

[0074] Next, external electrodes ( ) including metal films 61 , 62 and external terminal electrodes 71 , 72 are formed on the end faces of the body of the solid electrolytic capacitor 1 . Figure 6 :S15).

[0075] Next, each step will be described in more detail.

[0076] (Capacitor element sheet forming process)

[0077] Figure 7 This is a flowchart showing an example of a process for forming a capacitor element sheet. Figure 8 (A) is an external perspective view showing the shape of the anode electrode of the capacitor element before singulation. Figure 8 (B) is an external perspective view showing the shape of the capacitor element before being singulated. Fig. 9 This is the appearance picture of multiple pieces.

[0078] The anode electrode 11 is subjected to chemical treatment to form a dielectric layer 12 ( Figure 7 : S111). At this time, many holes are formed on the surface of the anode electrode 11 by etching, and the vicinity of the surface of the anode electrode 11 becomes a porous body. The dielectric layer 12 covers the surface of the anode electrode 11 including the inner surface of the hole.

[0079] Next, an anode through hole ( Figure 7 :S112). More specifically, Figure 8 As shown in (A), a plurality of cylindrical anode through holes 19C and a groove-shaped anode through holes 19L are formed in the anode electrode 11. The plurality of cylindrical anode through holes 19C and the groove-shaped anode through holes 19L are alternately arranged along the arrangement direction of the plurality of portions that become the anode electrodes 11. The plurality of cylindrical anode through holes 19C are formed at positions that realize the first end 10E1 of the anode electrode 11. The groove-shaped anode through hole 19L is formed at positions that straddle adjacent portions that become the anode electrodes 11 and at positions that realize the second end 10E2 of the adjacent anode electrode 11.

[0080] Next, a CP layer (solid electrolyte layer) 13 is formed on the surface of the dielectric layer 12 ( Figure 7 :S113). More specifically, Figure 8 As shown in (B), the first partition wall 14 having a frame-shaped opening is formed. Furthermore, the CP layer 13 (a laminated structure of the inner layer CP 131 and the outer layer CP 132 ) is formed in the opening of the first partition wall 14 .

[0081] The structure is as follows Fig. 9 As shown, the capacitor elements 10 (a structure including anode electrodes 11 , dielectric layers 12 , CP layers 13 , and first partition walls 14 ) are arranged two-dimensionally in a multi-sheet state.

[0082] (Cathode electrode sheet formation process)

[0083] Fig.10 It is an external perspective view showing the shape of the cathode electrode before being singulated.

[0084] like Fig.10 As shown, a plurality of cylindrical cathode through holes 29C and a groove-shaped cathode through hole 29L are formed in the cathode electrode 20. The plurality of cylindrical cathode through holes 29C and the groove-shaped cathode through holes 29L are alternately arranged along the arrangement direction of the plurality of portions that become the cathode electrodes 20. The plurality of cylindrical cathode through holes 29C are formed at the position of the first end 20E1 of the cathode electrode 20. The groove-shaped cathode through hole 29L is formed at the position that straddles the adjacent portions that become the cathode electrodes 20 and at the position of the adjacent second end 20E2 of the cathode electrode 20.

[0085] (Step of forming a sheet laminate)

[0086] Fig.11 This is a flowchart showing an example of a process for forming a sheet laminate. Fig.12 is an external perspective view showing a state where a second partition wall is formed on a capacitor element sheet. Fig.12 (A) shows the multi-chip state, Fig.12 (B) shows a portion of a capacitor element. Fig.13 is an external perspective view showing a state where a second partition wall and a first adhesive are formed on a capacitor element sheet. Fig.13 (A) shows the multi-chip state, Fig.13 (B) shows a portion of a capacitor element. Fig.14 (A) Fig.14 (B) is an exploded perspective view showing a state where the capacitor element sheet and the cathode electrode sheet are stacked. Fig.14 (A) Fig.14(B) shows a portion equivalent to a solid electrolytic capacitor. Fig.15 (A) is an exploded perspective view showing a stacked state of a plurality of capacitor element sheets and cathode electrode sheets, Fig.15 (B) is an external perspective view showing a stacked state of a plurality of capacitor element sheets and cathode electrode sheets.

[0087] The second partition wall 30 ( Fig.11 :S121). More specifically, Fig.12 (A) Fig.12 As shown in (B), the second partition wall 30 having a frame-shaped opening is formed.

[0088] Then, if Fig.13 (A) Fig.13 As shown in (B), a first adhesive 40 ( Fig.11 :S122).

[0089] Then, if Fig.14 (A) Fig.14 (B) Fig.15 (A) Fig.15 As shown in (B), capacitor element sheets and cathode electrode sheets are alternately stacked ( Fig.11 : S123). More specifically, the capacitor element sheet and the cathode electrode sheet are stacked to satisfy the following conditions.

[0090] When viewed in the stacking direction, the plurality of cylindrical anode through-holes 19C in the capacitor element sheet and the groove-shaped cathode through-holes 29L in the cathode electrode sheet overlap.

[0091] When viewed in the stacking direction, the groove-shaped anode through-holes 19L in the capacitor element sheet and the plurality of cylindrical cathode through-holes 29C in the cathode electrode sheet overlap.

[0092] When viewed in the stacking direction, the groove-shaped anode through-hole 19L in the capacitor element sheet and the groove-shaped cathode through-hole 29L in the cathode electrode sheet overlap.

[0093] Furthermore, a plurality of these through holes are formed in accordance with the number of capacitor elements arranged in the sheet laminate. Therefore, a plurality of through holes penetrating from the upper surface to the lower surface of the sheet laminate are formed in the sheet laminate.

[0094] Next, the sheet stack is heated and pressed ( Fig.11 : S124). Thus, the capacitor element sheet and the cathode electrode sheet are bonded together by the first adhesive 40, thereby forming a sheet stack. In addition, as described above, in the case of a structure in which the first adhesive 40 is omitted, step S122 can be omitted.

[0095] (Metal film and external terminal electrode formation process)

[0096] use Figure 3 (A) Figure 3 (B) Fig.16 , the steps of forming the metal films 61 , 62 and the external terminal electrodes 71 , 72 are described. Fig.16 This is a flowchart showing an example of a process for forming a metal film and an external terminal electrode.

[0097] like Figure 3 As shown in (A), the first end 10E1 of the anode electrode 11 and the outer surface of the first end 10E1 side of the insulating resin 50 are subjected to metal spraying. Similarly, the first end 20E1 of the cathode electrode 20 in the capacitor element stack 100 and the outer surface of the first end 20E1 side of the insulating resin 50 are subjected to metal spraying ( Fig.16 : S131). Thus, the metal film 61 is formed at the first end 10E1. Similarly, the metal film 62 is formed at the first end 20E1.

[0098] Next, use Figure 3 (B) shows an example of directly forming the external terminal electrodes 71 and 72 on the metal films 61 and 62 by sputtering or the like. Specifically, the external terminal electrode 71 is formed so as to cover the metal film 61. Similarly, the external terminal electrode 72 is formed so as to cover the metal film 62. At this time, the external terminal electrode 71 is formed to have an opening 751 on the first main surface 101 side. In addition, the external terminal electrode 72 is formed to have an opening 752 on the first main surface 101 side.

[0099] By using such a solid electrolytic capacitor 1, for example, the gas generated in the solid electrolytic capacitor 1 during MSL reflow soldering does not stay inside the solid electrolytic capacitor 1 but is released to the outside. Therefore, it is possible to suppress peeling and cracking caused by the gas generated in the solid electrolytic capacitor 1. That is, it is possible to realize a highly reliable solid electrolytic capacitor 1.

[0100] In the above structure, the metal films 61 and 62 are formed by thermal spraying. However, the metal films 61 and 62 may be formed by methods other than thermal spraying as long as the first pore diameter D1 is larger than the second pore diameter D2.

[0101] In addition, in the above-mentioned structure, the structure in which the metal film 62 and the external terminal electrode 72 are formed is shown. However, in the present invention, it is sufficient to have a structure in which at least the metal film 61 and the external terminal electrode 71 connected to the anode electrode 11 are provided so that the gas generated in the solid electrolytic capacitor 1 is released to the outside from the external electrode on the anode side. In other words, it is also possible to have a structure in which the external electrode on the cathode side is formed by a conventional method instead of the metal film 62 and the external terminal electrode 72.

[0102] In addition, in the above-mentioned structure, the external terminal electrodes 71 and 72 are shown to cover the entire side surface of the solid electrolytic capacitor 1 (the first end 10E1 side of the anode electrode 11 and the first end 20E1 side of the cathode electrode 20). However, the external terminal electrodes 71 and 72 can be shaped as long as a portion of the metal films 61 and 62 is exposed, so that the gas generated in the solid electrolytic capacitor 1 can be released to the outside. However, the so-called shape covering the entirety also includes the case where the shape does not strictly cover the entirety due to unexpected deviations during processing.

[0103] That is, in the above structure, an example is shown in which the opening 751 of the external terminal electrode 71 and the opening 752 of the external terminal electrode 72 are formed on the side of the first main surface 101. However, the openings 751 and 752 are not limited to the side of the first main surface 101, and the formation position is not limited as long as there is no problem in installation. For example, except for the following range, the openings 751 and 752 can be in any position, that is, they will be covered by solder or conductive adhesive material during installation, so that the gas generated in the solid electrolytic capacitor 1 cannot be released to the outside. Furthermore, the openings 751 and 752 only need to have a size, shape, and number of openings that can release gas.

[0104] [Second embodiment]

[0105] Next, a solid electrolytic capacitor according to a second embodiment will be described with reference to the drawings. Fig.17 It is a side cross-sectional view showing a schematic structure of a solid electrolytic capacitor in a second embodiment.

[0106] like Fig.17 As shown, the solid electrolytic capacitor 1A according to the second embodiment is different from the solid electrolytic capacitor 1 according to the first embodiment in that it includes a conductive resin layer. The other structures of the solid electrolytic capacitor 1A are the same as those of the solid electrolytic capacitor 1, and the description of the same parts is omitted.

[0107] In the second embodiment, using Fig.17An example is shown in which the metal films 61 and 62 are formed into external terminal electrodes 71 and 72 in a molded state by a conductive adhesive. Specifically, the metal film 61 is formed by metallizing the first end 10E1 of the anode electrode 11 and the outer surface of the first end 10E1 side of the insulating resin 50. The conductive resin layer 81 is formed so as to cover the surface (outer surface side) of the metal film 61 facing the first end 10E1. Furthermore, the external terminal electrode 71 is formed so as to cover the conductive resin layer 81.

[0108] Similarly, metal film 62 is formed by metallization on the first end 20E1 of cathode electrode 20 and the outer surface of the first end 20E1 side of insulating resin 50. Conductive resin layer 82 is formed so as to cover the surface (outer surface side) of the metal film 62 facing the first end 20E1. Furthermore, external terminal electrode 72 is formed so as to cover conductive resin layer 82.

[0109] In the second embodiment, a structure in which the metal film 62 and the external terminal electrode 72 are formed is shown. However, any structure may be used as long as at least the metal film 61 and the external terminal electrode 71 connected to the anode electrode 11 are provided so that the gas generated in the solid electrolytic capacitor 1 is released to the outside from the external electrode on the anode side. In other words, a structure in which the external electrode on the cathode side is formed by a conventional method instead of the metal film 62 and the external terminal electrode 72 may be used.

[0110] By forming in this way, the bonding strength between the metal film 61 and the external terminal electrode 71 becomes high. Similarly, the bonding strength between the metal film 62 and the external terminal electrode 72 becomes high.

[0111] That is, the area where the metal film 61 and the external terminal electrode 71 abut against each other and the area where the metal film 62 and the external terminal electrode 72 abut against each other can be ensured, so that the conductivity can be ensured. Furthermore, the conductive resin layers 81 and 82 can suppress the peeling caused by the difference in linear expansion coefficient between the conductive resin layer 81, the metal film 61 and the external terminal electrode 71, and between the conductive resin layer 82, the metal film 62 and the external terminal electrode 72.

[0112] Similarly, the area where the metal film 62 and the external terminal electrode 72 are in contact can be ensured, so that conductivity can be ensured. Furthermore, the conductive resin layer 82 can suppress peeling caused by the difference in linear expansion coefficient between the metal film 62 and the external terminal electrode 72.

[0113] When such a solid electrolytic capacitor 1A is used, the gas generated at the anode electrode 11 during, for example, MSL reflow soldering does not stay inside the solid electrolytic capacitor 1A, but is released to the outside. Therefore, peeling and cracking caused by the gas generated in the solid electrolytic capacitor 1A can be suppressed. Furthermore, the conductivity of the metal film 61, the conductive resin layer 81 and the external terminal electrode 71, and the conductivity of the metal film 62, the conductive resin layer 82 and the external terminal electrode 72 can be ensured. That is, a highly reliable solid electrolytic capacitor 1A can be realized.

[0114] [Third Embodiment]

[0115] Next, a solid electrolytic capacitor according to a third embodiment will be described with reference to the drawings. Fig.18 It is a side cross-sectional view showing a schematic structure of a solid electrolytic capacitor in a third embodiment.

[0116] like Fig.18 As shown, the solid electrolytic capacitor 1B according to the third embodiment is different from the solid electrolytic capacitor 1 according to the first embodiment in that it includes a non-conductive resin layer. The other structures of the solid electrolytic capacitor 1B are the same as those of the solid electrolytic capacitor 1, and the description of the same parts is omitted.

[0117] like Fig.18 As shown, the metal film 61 is formed by performing metal spraying on the first end 10E1 of the anode electrode 11 and the outer surface of the first end 10E1 side of the insulating resin 50. The non-conductive resin layer 91 is formed so as to cover the surface (outer surface side) of the metal film 61 that is opposite to the first end 10E1. At this time, a part of the surface of the metal film 61 has a part that is not covered by the non-conductive resin layer 91. Furthermore, the external terminal electrode 71 is formed so as to cover the non-conductive resin layer 91. As for the shape of the non-conductive resin layer 91, it does not matter as long as the metal film 61 and the external terminal electrode 71 can be used as an anode electrode.

[0118] Similarly, the metal film 62 is formed by performing metal spraying on the first end 20E1 of the cathode electrode 20 and the outer surface of the first end 20E1 side of the insulating resin 50. The non-conductive resin layer 92 is formed so as to cover the surface (outer surface side) of the metal film 62 that is opposite to the first end 20E1. At this time, a part of the surface of the metal film 62 has a part that is not covered by the non-conductive resin layer 92. Furthermore, the external terminal electrode 72 is formed so as to cover the non-conductive resin layer 92. As for the shape of the non-conductive resin layer 92, it does not matter as long as the metal film 62 and the external terminal electrode 72 can be used as a cathode electrode.

[0119] By forming in this way, the bonding strength between the metal film 61 and the external terminal electrode 71 becomes high. Similarly, the bonding strength between the metal film 62 and the external terminal electrode 72 becomes high.

[0120] That is, by providing the non-conductive resin layers 91 and 92 , it is possible to suppress peeling caused by differences in linear expansion coefficients between the conductive resin layer 81 , the metal film 61 , and the external terminal electrode 71 , and between the conductive resin layer 82 , the metal film 62 , and the external terminal electrode 72 .

[0121] When such a solid electrolytic capacitor 1B is used, the gas generated in the anode electrode 11 during, for example, MSL reflow soldering does not stay inside the solid electrolytic capacitor 1B, but is released to the outside. Therefore, peeling and cracking caused by the gas generated in the solid electrolytic capacitor 1B can be suppressed. That is, a highly reliable solid electrolytic capacitor 1B can be realized. In addition, by using a non-conductive resin, it can be formed at a low cost compared to the conductive resin used in the second embodiment.

[0122] [Fourth embodiment]

[0123] Next, a solid electrolytic capacitor according to a fourth embodiment will be described with reference to the drawings. Fig.19 It is a side cross-sectional view showing a schematic structure of a solid electrolytic capacitor in a fourth embodiment.

[0124] like Fig.19 As shown, the solid electrolytic capacitor 1C according to the fourth embodiment is different from the solid electrolytic capacitor 1A according to the second embodiment in the structure of the conductive resin layer. The other structures of the solid electrolytic capacitor 1C are the same as those of the solid electrolytic capacitor 1A, and the description of the same parts is omitted.

[0125] like Fig.19 As shown, the conductive resin layer 81 penetrates the metal film 61. More specifically, the conductive resin layer 81 penetrates to a thickness (T61 / 2) that is half the thickness T61 of the metal film 61. However, the so-called half thickness also includes the case where the conductive resin layer 81 does not strictly speaking reach a thickness that is half the thickness T61 of the metal film 61 due to unexpected processing variations and the like.

[0126] From the perspective of long-term use, oxygen and water vapor from the outside may intrude into the metal film 61, causing the inside of the solid electrolytic capacitor 1C to deteriorate. However, by making the conductive resin layer 81 penetrate the metal film 61 to a certain thickness (about half the thickness of the metal film 61 in the above example), the intrusion of oxygen and water vapor can be prevented.

[0127] That is, by providing the above-described structure, it is possible to release gas to the outside of the solid electrolytic capacitor 1C, and it is possible to take into account both the intrusion of oxygen and water vapor into the solid electrolytic capacitor 1C from the outside.

[0128] In addition, in the fourth embodiment, the structure of the conductive resin layers 81 and 82 is shown. However, even if the non-conductive resin layers 91 and 92 are used as in the third embodiment, the same operation and effect can be obtained.

[0129] (Description of an Example of Specific Materials and the Like of Each Component of the Solid Electrolytic Capacitor 1)

[0130] (Capacitor element 10)

[0131] Capacitor element 10 is realized by, for example, the following materials and thicknesses.

[0132] Anode electrode 11 includes, for example, a single metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or an alloy thereof. Anode electrode 11 is preferably aluminum or an aluminum alloy. Anode electrode 11 may be any valve-acting metal that exhibits a so-called valve action.

[0133] The anode electrode 11 is preferably in the form of a flat plate, and the thickness of the core portion (the central portion where the pores of the porous body do not reach) of the anode electrode 11 is preferably 5 μm or more and 100 μm or less. The thickness (thickness of one side) of the porous portion (the portion of the porous body where the pores are formed) is preferably 5 μm or more and 200 μm or less.

[0134] The dielectric layer 12 is preferably composed of an oxide film of the anode electrode 11. For example, when aluminum foil is used for the anode electrode 11, the dielectric layer 12 is formed by oxidation in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or sodium salts, ammonium salts thereof, etc. The thickness of the dielectric layer 12 is preferably 1 nm or more and 100 nm or less.

[0135] The inner layer CP131 is realized by, for example, a conductive polymer having a pyrrole, thiophene, aniline or the like as a skeleton, or PEDOT [poly (3, 4-ethylenedioxythiophene)] which is a conductive polymer having a thiophene as a skeleton, and may be a layer of PEDOT:PSS compounded with polystyrene sulfonic acid (PSS) as a dopant. The inner layer CP131 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 12 using a treatment liquid containing a monomer of 3, 4-ethylenedioxythiophene or the like, a method of applying a dispersion of a polymer of poly (3, 4-ethylenedioxythiophene) or the like on the surface of the dielectric part and drying it, etc.

[0136] The thickness of the outer layer CP132 is preferably 2 μm or more and 20 μm or less. The material of the outer layer CP132 is the same as that of the inner layer CP131.

[0137] As the first adhesive 40 , for example, a mixture of insulating resin such as epoxy resin or phenol resin and conductive particles such as carbon and silver is preferably used.

[0138] The cathode electrode 20 is formed of, for example, aluminum, titanium, copper, silver, etc. The thickness of the cathode electrode 20 is, for example, thinner than or equal to the thickness of the anode electrode 11. The thickness of the cathode electrode 20 is preferably as thin as possible, about 5 μm to 50 μm, preferably about 30 μm.

[0139] The insulating resin 50 may also contain a filler. As the resin, for example, epoxy resin, phenolic resin, polyimide resin, silicone resin, polyamide resin, liquid crystal polymer, etc. are preferred. As the filler, for example, insulating oxide particles such as silica particles, alumina particles, titanium dioxide particles, and zirconium oxide particles are preferred. The maximum diameter of the filler is preferably 30 μm or more and 40 μm or less, for example. For example, a material containing silica particles in a solid epoxy resin and a phenolic resin is more preferred.

[0140] The metal films 61 and 62 are preferably formed by a metal that can be sprayed. By using spraying, the first pore diameter D1 of the metal films 61 and 62 can be easily made larger than the second pore diameter D2 of the porous portion of the anode electrode 11. This is considered to be because, when the metal film 61 is formed by spraying, for example, relatively large metal particles in a molten state or a semi-molten state reach the first end 10E1 of the anode electrode 11 and the outer surface of the first end 10E1 side of the insulating resin 50, and the large metal particles are cooled and solidified, thereby easily forming pores. The same is true for the metal film 62.

[0141] For example, Au, Cu, or 42 alloy is preferably used for the external terminal electrodes 71 and 72. The external terminal electrodes 71 and 72 may be made of any material as long as the surface of the external terminal electrodes 71 and 72 has high wettability with solder.

[0142] The conductive resin layers 81 and 82 are thermosetting resins having conductivity, for example, phenolic resins are suitable.

[0143] The non-conductive resin layers 91 and 92 are non-conductive thermosetting resins, such as epoxy resins.

[0144] Description of Reference Numerals

[0145] D1: the first pore diameter;

[0146] D2: the second pore diameter;

[0147] E11: Cutting line;

[0148] S11: Cutting line;

[0149] T61: thickness of metal film;

[0150] 1. 1A, 1B, 1C: solid electrolytic capacitors;

[0151] 10: Capacitor components;

[0152] 10E1: End 1;

[0153] 10E2: End 2;

[0154] 11: anode electrode;

[0155] 12: dielectric layer;

[0156] 13: CP layer;

[0157] 131: inner CP;

[0158] 132: Outer CP;

[0159] 14: 1st partition wall;

[0160] 19C: through hole for anode;

[0161] 19L: through hole for anode;

[0162] 20: cathode electrode;

[0163] 20E1: End 1;

[0164] 20E2: End 2;

[0165] 29C: through hole for cathode;

[0166] 29L: through hole for cathode;

[0167] 30: 2nd partition wall;

[0168] 40: 1st adhesive;

[0169] 50: Insulating resin;

[0170] 61, 62: Metal film;

[0171] 71, 72: external terminal electrodes;

[0172] 81, 82: conductive resin layer;

[0173] 91, 92: non-conductive resin layer;

[0174] 100: capacitor element laminate;

[0175] 101: 1st main surface;

[0176] 102: 2nd main surface;

[0177] 751, 752: Open your mouth.

Claims

1. A solid electrolytic capacitor comprising: A sheet laminate formed by alternately laminating a plurality of flat film-shaped capacitor elements and a plurality of flat film-shaped cathode electrode foils, wherein the flat film-shaped capacitor elements have a dielectric layer and a solid electrolyte layer sequentially formed on the surface of the flat film-shaped anode electrode foil, and the flat film-shaped anode electrode foil has a porous portion at a given depth from the surface; a first metal portion formed at an end portion of the anode electrode foil and an end portion of the solid electrolyte layer in the sheet laminate; and Insulating resin is used to seal the sheet stack. The first pore diameter of the first metal portion is larger than the second pore diameter of the porous portion of the anode electrode foil.

2. The solid electrolytic capacitor according to claim 1, wherein: The invention comprises a second metal portion covering a part of the first metal portion.

3. The solid electrolytic capacitor according to claim 2, wherein: The first metal portion and the second metal portion are bonded to each other via a conductive resin.

4. The solid electrolytic capacitor according to claim 3, wherein: The conductive resin penetrates to approximately 1 / 2 of the thickness of the first metal portion.

5. The solid electrolytic capacitor according to claim 2, wherein: The solid electrolytic capacitor includes a non-conductive resin partially in contact with the first metal portion and the second metal portion.

6. The solid electrolytic capacitor according to claim 5, wherein: The non-conductive resin penetrates to approximately 1 / 2 of the thickness of the first metal portion.

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