Solid electrolytic capacitor and method for manufacturing the same

Abstract

To provide a solid electrolytic capacitor and a method of manufacturing a solid electrolytic capacitor, capable of suppressing the damage of a solid electrolyte layer.SOLUTION: A solid electrolytic capacitor includes: a porous sintered body 1 having a first surface 11 and containing a valve action metal; an anode wire 10 protruding from the first surface 11 and containing a valve action metal; a dielectric layer 2 formed on the porous sintered body 1; a solid electrolyte layer 3 formed on the dielectric layer 2; and a cathode layer 4 formed on the solid electrolyte layer 3. The solid electrolyte layer 3 includes a first layer 31 formed on the dielectric layer 2 and a second layer 32 formed on the first layer 31. The solid electrolytic capacitor includes a protective layer 5 that covers at least part of the first surface 11 via the first layer 31.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solid electrolytic capacitor and a method for manufacturing a solid electrolytic capacitor. [Background technology]

[0002] Patent Document 1 discloses an example of a conventional solid electrolytic capacitor. The solid electrolytic capacitor disclosed in this document includes a porous sintered body from which an anode wire protrudes, a dielectric layer, a solid electrolyte layer, a cathode layer, an anode terminal, a cathode terminal, and a sealing resin. The porous sintered body and the anode wire are made of a valve metal such as Ta (tantalum) or Nb (niobium). The solid electrolyte layer is made of a conductive polymer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-168621 Summary of the Invention [Problem to be solved by the invention]

[0004] The solid electrolyte layer may be damaged during the process of joining the anode wire to the anode terminal or during use.

[0005] The present invention has been devised in light of the above circumstances, and an object of the present invention is to provide a solid electrolytic capacitor capable of suppressing damage to the solid electrolyte layer, and a method for manufacturing the solid electrolytic capacitor. [Means for solving the problem]

[0006] A solid electrolytic capacitor provided by a first aspect of the present invention comprises: a porous sintered body having a first surface and containing a valve metal; an anode wire protruding from the first surface and containing a valve metal; a dielectric layer formed on the porous sintered body; a solid electrolyte layer formed on the dielectric layer; and a cathode layer formed on the solid electrolyte layer, wherein the solid electrolyte layer includes a first layer formed on the dielectric layer and a second layer formed on the first layer, and comprises a protective layer covering at least a portion of the first surface via the first layer.

[0007] A second aspect of the present invention provides a method for manufacturing a solid electrolytic capacitor, comprising the steps of: forming a porous sintered body containing a valve metal and having a first surface from which an anode wire containing a valve metal protrudes; forming a dielectric layer on the porous sintered body; forming a solid electrolyte layer on the dielectric layer; and forming a cathode layer on the solid electrolyte layer, wherein the step of forming the solid electrolyte layer comprises the steps of forming a first layer on the dielectric layer and forming a second layer on the first layer; and, after the step of forming the first layer, forming a protective layer that covers at least a portion of the first surface. [Effects of the Invention]

[0008] According to the present disclosure, damage to the solid electrolyte layer can be suppressed.

[0009] Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing a solid electrolytic capacitor according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a main portion of the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 3] FIG. 3 is a flow diagram showing a method for manufacturing a solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 4]FIG. 4 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 5] FIG. 5 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 7] FIG. 7 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 8] FIG. 8 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 9] FIG. 9 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 10] FIG. 10 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 11] FIG. 11 is a cross-sectional view showing a solid electrolytic capacitor according to a second embodiment of the present disclosure. [Figure 12] FIG. 12 is a flowchart showing a method for manufacturing a solid electrolytic capacitor according to the second embodiment of the present disclosure. [Figure 13] FIG. 13 is a cross-sectional view illustrating a method for manufacturing a solid electrolytic capacitor according to a second embodiment of the present disclosure. [Figure 14] FIG. 14 is a cross-sectional view showing a solid electrolytic capacitor according to a third embodiment of the present disclosure. [Figure 15] FIG. 15 is a flowchart showing a method for manufacturing a solid electrolytic capacitor according to a third embodiment of the present disclosure. [Figure 16] FIG. 16 is a cross-sectional view illustrating a method for manufacturing a solid electrolytic capacitor according to a third embodiment of the present disclosure. [Figure 17] FIG. 17 is a cross-sectional view showing a solid electrolytic capacitor according to a fourth embodiment of the present disclosure. [Figure 18] FIG. 18 is an enlarged cross-sectional view of a main portion of a solid electrolytic capacitor according to a fourth embodiment of the present disclosure. [Figure 19]FIG. 19 is a flowchart showing a method for manufacturing a solid electrolytic capacitor according to a fourth embodiment of the present disclosure. [Figure 20] FIG. 20 is a cross-sectional view illustrating a method for manufacturing a solid electrolytic capacitor according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0012] In the present disclosure, "A is formed on B" includes cases where A is in direct contact with B and cases where A is provided in a position where it overlaps with B via another object.

[0013] The terms "first," "second," "third," etc. in this disclosure are used for identification purposes only and are not intended to impose any ranking on their objects.

[0014] First Embodiment 1 and 2 show a solid electrolytic capacitor according to a first embodiment of the present disclosure. The solid electrolytic capacitor A1 of this embodiment includes a porous sintered body 1, an anode wire 10, a dielectric layer 2, a solid electrolyte layer 3, a cathode layer 4, a protective layer 5, an anode conductor 6, a cathode conductor 7, and a sealing resin 8.

[0015] The porous sintered body 1 contains a valve metal and is formed, for example, by sintering an intermediate product obtained by compressing a fine powder of the valve metal, and has many pores therein. Examples of the valve metal contained in the porous sintered body 1 include Ta (tantalum) and Nb (niobium). The porous sintered body 1 of this embodiment has a first surface 11 and a second surface 12. When the porous sintered body 1 has a rectangular parallelepiped shape, the first surface 11 is one surface constituting the rectangular parallelepiped, and the second surface 12 is four surfaces connected to the first surface 11. Alternatively, when the porous sintered body 1 has a cylindrical shape, the first surface 11 is one end surface, and the second surface 12 is a peripheral side surface connected to the first surface 11.

[0016] The anode wire 10 protrudes from the first surface 11 of the porous sintered body 1, with a portion of the anode wire 10 penetrating into the porous sintered body 1. The anode wire 10 contains a valve metal. Examples of the valve metal contained in the porous sintered body 1 include Ta (tantalum) and Nb (niobium). The valve metal contained in the anode wire 10 is preferably the same as the valve metal contained in the porous sintered body 1.

[0017] The dielectric layer 2 is formed on the porous sintered body 1. The dielectric layer 2 is in direct contact with the porous sintered body 1. In this embodiment, the dielectric layer 2 is formed on a portion of the anode wire 10 and is in direct contact with that portion. The dielectric layer 2 covers the outer surface of the porous sintered body 1, including the first surface 11 and the second surface 12, and the pores inside the porous sintered body 1. The dielectric layer 2 contains, for example, an oxide of a valve metal, specific examples of which include Ta2O5 (tantalum pentoxide) and Nb2O5 (niobium pentoxide).

[0018] The solid electrolyte layer 3 is formed on the dielectric layer 2. The solid electrolyte layer 3 is in direct contact with the dielectric layer 2. The solid electrolyte layer 3 includes a first layer 31 and a second layer 32. The first layer 31 is formed on the dielectric layer 2 and is in direct contact with the dielectric layer 2. The second layer 32 is formed on the first layer 31 and is in direct contact with the first layer 31. The first layer 31 includes portions formed on the first surface 11 and the second surface 12 with the dielectric layer 2 interposed therebetween. In the illustrated example, the first layer 31 includes a portion formed on a part of the anode wire 10 with the dielectric layer 2 interposed therebetween. The second layer 32 includes a portion formed on the second surface 12 with the dielectric layer 2 and the first layer 31 interposed therebetween, and is provided at a position that avoids the first surface 11. The first layer 31 and the second layer 32 include, for example, a conductive polymer. Specific examples of conductive polymers include polypyrrole, polythiophene, polyaniline, and polyfuran.

[0019] The cathode layer 4 is formed on the solid electrolyte layer 3. The cathode layer 4 is in direct contact with the second layer 32 of the solid electrolyte layer 3. The cathode layer 4 of this embodiment includes a graphite layer 41 and a metal layer 42. The graphite layer 41 is formed on the solid electrolyte layer 3 and in direct contact with the second layer 32. The graphite layer 41 contains graphite. The metal layer 42 is formed on the graphite layer 41 and in direct contact with the graphite layer 41. The metal layer 42 contains, for example, Ag (silver). The cathode layer 4 of this embodiment is formed on the outer surface of the porous sintered body 1, including the second surface 12, and is provided at a position avoiding the first surface 11.

[0020] The protective layer 5 covers at least a portion of the first surface 11 via the dielectric layer 2 and the first layer 31. The protective layer 5 includes an insulating material. Examples of insulating materials included in the protective layer 5 include fluororesin, silicone resin, and acrylic resin. Preferred examples of insulating materials include PVF (Polyvinyl Fluoride), ETFE (Ethylene Tetrafluoroethylene), FEP (Fluorinated Ethylene Propylene), PFA (a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene), PTEF (Polytetrafluoroethylene), fluoroolefin-vinyl ether copolymer (FEVE: Fluorethylene Vinyl Ether), and a mixture of polyvinylidene fluoride and acrylic resin (PVDF: Polyvinylidene DiFluoride). The protective layer 5 of this embodiment is in direct contact with the first layer 31.

[0021] The protective layer 5 of this embodiment has a first portion 51. The first portion 51 covers substantially the entire first surface 11. The first portion 51 is provided at a position that avoids the second surface 12. The second layer 32 is formed at a position that avoids the protective layer 5 (first portion 51). The protective layer 5 (first portion 51) covers a portion of the anode wire 10 via both the dielectric layer 2 and the solid electrolyte layer 3, or via only the dielectric layer 2. In this embodiment, the thickness t3 from the first surface 11 to the surface of the protective layer 5 (first portion 51) is greater the closer to the anode wire 10. The thickness t3 corresponds to the third thickness in this disclosure.

[0022] The anode conduction member 6 is a member that electrically connects the porous sintered body 1 and the anode wire 10 to a circuit (not shown) on which the solid electrolytic capacitor A1 is mounted. The specific configuration of the anode conduction member 6 is not limited in any way, and in this embodiment, it includes a terminal portion 61 and a relay portion 62.

[0023] The terminal portion 61 has a portion exposed from the sealing resin 8 and is used as a mounting terminal when the solid electrolytic capacitor A1 is mounted. The terminal portion 61 includes a metal such as copper (Cu). The mounting surface of the terminal portion 61 may be provided with a plating layer (not shown) of tin (Sn), nickel (Ni), or the like.

[0024] The relay portion 62 relays the anode wire 10 and the terminal portion 61, and is bonded to both the anode wire 10 and the terminal portion 61. The relay portion 62 contains a metal such as copper (Cu). The method for bonding the relay portion 62 to the anode wire 10 and the terminal portion 61 is not limited in any way. The relay portion 62 and the anode wire 10 are bonded together by, for example, laser welding. The terminal portion 61 and the relay portion 62 are bonded together by, for example, laser welding, resistance welding, or another welding method, or by a bonding method using a conductive bonding material.

[0025] The cathode conductor 7 is a member that electrically connects the cathode layer 4 to a circuit (not shown) on which the solid electrolytic capacitor A1 is mounted. The specific configuration of the cathode conductor 7 is not limited in any way, and in this embodiment, it is made of a plate-like member. The cathode conductor 7 contains a metal such as copper (Cu). A plating layer (not shown) of tin (Sn), nickel (Ni), or the like may be provided on the mounting surface of the cathode conductor 7. The cathode conductor 7 is electrically connected to the cathode layer 4 via a conductive bonding material 79. The conductive bonding material 79 contains, for example, silver (Ag).

[0026] The sealing resin 8 covers the porous sintered body 1, the anode wire 10, the dielectric layer 2, the solid electrolyte layer 3, the cathode layer 4, the protective layer 5, and a portion of each of the anode conductor 6 and the cathode conductor 7. The sealing resin 8 contains, for example, an epoxy resin. A portion of each of the anode conductor 6 and the cathode conductor 7 is exposed from the sealing resin 8.

[0027] Next, a method for manufacturing the solid electrolytic capacitor A1 will be described below with reference to FIGS.

[0028] 3, the method for manufacturing the solid electrolytic capacitor A1 includes the steps of forming a porous sintered body 1, forming a dielectric layer 2, forming a solid electrolyte layer 3 (first layer 31), forming a protective layer 5, forming a solid electrolyte layer 3 (second layer 32), forming a cathode layer 4 (graphite layer 41), forming a cathode layer 4 (metal layer 42), bonding to an anode conductor 6, bonding to a cathode conductor 7, and forming a sealing resin 8. In this embodiment, the step of forming the protective layer 5 is performed after the step of forming the first layer 31 and before the step of forming the second layer 32.

[0029] First, as shown in FIG. 4, an intermediate product 100 is formed. The intermediate product 100 is formed by pressurizing a fine powder of a valve metal such as Ta (tantalum) or Nb (niobium). This pressurizing is performed with the anode wire 10 inserted into the valve metal fine powder. This results in an intermediate product 100 with the anode wire 10 protruding from the first surface 11. Next, the intermediate product 100 is subjected to a sintering process. This results in a porous sintered body 1.

[0030] Next, the dielectric layer 2 is formed. For example, as shown in FIG. 5, the dielectric layer 2 is formed by anodizing the porous sintered body 1 and a portion of the anode wire 10 while they are immersed in a chemical conversion solution 200. The chemical conversion solution 200 can be, for example, an aqueous solution of phosphoric acid. This results in the dielectric layer 2 that covers the outer surface and pores of the porous sintered body 1 and a portion of the anode wire 10.

[0031] Next, the first layer 31 is formed. For example, as shown in FIG. 6 , the first layer 31 is formed by chemical polymerization or electrolytic polymerization of the porous sintered body 1 on which the dielectric layer 2 has been formed. In these polymerization processes, for example, the porous sintered body 1 on which the dielectric layer 2 has been formed is immersed in a reaction solution 310 containing a monomer. In this embodiment, the porous sintered body 1 and a portion of the anode wire 10 are immersed in the reaction solution 310. However, the portion of the anode wire 10 exposed from the dielectric layer 2 is not immersed in the reaction solution 310. The polymerization process forms the first layer 31. The first layer 31 is formed on the surface of the porous sintered body 1, including the first surface 11 and the second surface 12, and on a portion of the anode wire 10. The first layer 31 is laminated on the dielectric layer 2. After the first layer 31 is formed, a second chemical conversion treatment may be performed.

[0032] Next, the protective layer 5 is formed. The protective layer 5 is formed by applying a resin paste 500 using a dispenser Ds, for example, as shown in FIG. 7 . The dispenser Ds is a device capable of applying a fixed amount of resin paste 500. The resin paste 500 is a material that constitutes the insulating material contained in the protective layer 5. In this embodiment, the resin paste 500 is applied using the dispenser Ds so as to cover the first surface 11. At this time, the resin paste 500 is not applied onto the second surface 12. The resin paste 500 also covers a portion of the anode wire 10 via the dielectric layer 2 and the first layer 31. The protective layer 5 is obtained by subjecting the resin paste 500 to predetermined processes such as drying, heating, and ultraviolet irradiation.

[0033] Next, the second layer 32 is formed. The second layer 32 is formed, for example, by performing a chemical polymerization process or an electrolytic polymerization process on the porous sintered body 1 on which the dielectric layer 2, the first layer 31, and the protective layer 5 are formed, as shown in FIG. 7 . In these polymerization processes, for example, the porous sintered body 1 on which the dielectric layer 2, the first layer 31, and the protective layer 5 are formed is immersed in a reaction solution 320 containing a monomer. In this embodiment, the protective layer 5 (first surface 11) is not immersed in the reaction solution 320. By performing the polymerization process, the second layer 32 is formed, as shown in FIG. 9 . The second layer 32 is formed on the outer surface of the porous sintered body 1 excluding the first surface 11, and is in direct contact with the first layer 31. After the second layer 32 is formed, a chemical conversion treatment may be performed again.

[0034] 10 , a step of forming a graphite layer 41 and a step of forming a metal layer 42 are performed. This results in a cathode layer 4 consisting of the graphite layer 41 and the metal layer 42. The cathode layer 4 is formed on the outer surface of the porous sintered body 1 except for the first surface 11, and is in direct contact with the second layer 32 of the solid electrolyte layer 3.

[0035] This is followed by a step of joining the anode conductor 6 to the anode wire 10 and a step of joining the cathode conductor 7 to the metal layer 42 of the cathode layer 4. Then, a sealing resin 8 is formed to cover the porous sintered body 1 having the dielectric layer 2, solid electrolyte layer 3, cathode layer 4, and protective layer 5 formed thereon, the anode wire 10, and parts of the anode conductor 6 and cathode conductor 7. This completes the solid electrolytic capacitor A1 described above.

[0036] Next, the effects of the solid electrolytic capacitor A1 and the method for manufacturing the solid electrolytic capacitor A1 will be described.

[0037] As shown in FIGS. 1 and 2 , a first layer 31 is formed on the first surface 11 of the porous sintered body 1. In a method for manufacturing the solid electrolytic capacitor A1, a load may be applied to the base of the anode wire 10, for example, during laser welding to join the anode wire 10 to the relay portion 62, or during use of the solid electrolytic capacitor A1. There is a concern that this load may damage the first layer 31. According to this embodiment, the first layer 31 on the first surface 11 is covered with the protective layer 5 (first portion 51). Therefore, according to this embodiment, damage to the solid electrolyte layer 3 can be suppressed.

[0038] The first portion 51 is formed on the entire surface of the first surface 11. This makes it possible to more reliably protect the first layer 31 on the first surface 11.

[0039] 2, the thickness t3 from the first surface 11 to the surface of the protective layer 5 (first portion 51) is greater the closer it is to the anode wire 10. This makes it possible to more reliably protect the first layer 31 located closer to the anode wire 10 when a load is applied to the base of the anode wire 10.

[0040] The protective layer 5 is preferably made of one of the fluororesins exemplified above, which can be easily dispersed in a solvent during the manufacturing process and exhibits high weather resistance. The fluororesin contained in the protective layer 5 has a glass transition temperature of 150°C or lower, preferably 120°C or lower, and more preferably 100°C or lower.

[0041] 7, in this embodiment, the resin paste 500 is applied using a dispenser Ds to form the protective layer 5. This allows the resin paste 500 to be applied more accurately to the worn area.

[0042] 11 to 20 show other embodiments of the present invention. In these figures, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as those in the above embodiment.

[0043] Second Embodiment 11 shows a solid electrolytic capacitor according to a second embodiment of the present disclosure. In the solid electrolytic capacitor A2 of this embodiment, a protective layer 5 is formed on a second layer 32.

[0044] In this embodiment, the second layer 32 has a portion formed on the first surface 11. This portion is in direct contact with the first layer 31. The first portion 51 of the protective layer 5 is in direct contact with the second layer 32.

[0045] 12 and 13 show a method for manufacturing the solid electrolytic capacitor A2. As shown in Fig. 12, in this embodiment, the step of forming the protective layer 5 is performed after the step of forming the second layer 32 and before the step of forming the graphite layer 41.

[0046] 13, after the second layer 32 is formed, the first surface 11 of the porous sintered body 1 is covered with the dielectric layer 2, the first layer 31, and the second layer 32. That is, in the chemical polymerization treatment or electrolytic polymerization treatment shown with reference to FIG. 8, the first surface 11 and a portion of the anode wire 10 are immersed in a reaction liquid 320. Then, in the step shown in FIG. 13, a resin paste 500 is applied to the second layer 32 formed on the first surface 11 using a dispenser Ds.

[0047] This embodiment also makes it possible to suppress damage to the solid electrolyte layer 3. Furthermore, this embodiment makes it possible to protect the first layer 31 and the second layer 32 on the first surface 11 by the protective layer 5 (first portion 51).

[0048] Third Embodiment 14 shows a solid electrolytic capacitor according to a third embodiment of the present disclosure. In the solid electrolytic capacitor A3 of this embodiment, a protective layer 5 is formed on a graphite layer 41.

[0049] In this embodiment, the protective layer 5 has a first portion 51 and a second portion 52. The first portion 51 is formed on the first surface 11. The dielectric layer 2, the first layer 31, and the second layer 32 are interposed between the first portion 51 and the first surface 11. The first portion 51 is in direct contact with the second layer 32.

[0050] Second portion 52 is formed on second surface 12. In the present embodiment, dielectric layer 2, first layer 31, second layer 32, and graphite layer 41 are interposed between second portion 52 and second surface 12. Second portion 52 is in direct contact with graphite layer 41. The portion of graphite layer 41 that is not covered by second portion 52 is covered by metal layer 42. Part of second portion 52 may be covered by metal layer 42.

[0051] 15 and 16 show a method for manufacturing the solid electrolytic capacitor A3. As shown in Fig. 15, in this embodiment, the step of forming the protective layer 5 is performed after the step of forming the graphite layer 41 and before the step of forming the metal layer 42.

[0052] 16 , after graphite layer 41 is formed, resin paste 500 is applied using dispenser Ds. In the illustrated example, resin paste 500 is applied onto substantially the entire surface of first surface 11 and onto a portion of second surface 12. Resin paste 500 applied onto first surface 11 contacts second layer 32. Resin paste 500 applied onto second surface 12 contacts graphite layer 41.

[0053] The application of resin paste 500 onto second surface 12 may be performed intentionally, or may be the result of a portion of resin paste 500 extending onto second surface 12 in order to more reliably apply resin paste 500 to the entire surface of first surface 11. For this reason, the boundary between first surface 11 and second surface 12 is not limited to a configuration in which the entire length is covered with resin paste 500 (protective layer 5). It may also be a configuration in which only a portion of the boundary is covered with resin paste 500 (protective layer 5).

[0054] This embodiment also makes it possible to suppress damage to solid electrolyte layer 3. Furthermore, according to this embodiment, a portion of graphite layer 41 is covered with protective layer 5 (second portion 52). This makes it possible to suppress peeling or cracks from occurring at the end of graphite layer 41.

[0055] <Fourth embodiment> 17 and 18 show a solid electrolytic capacitor according to a fourth embodiment of the present disclosure. In the solid electrolytic capacitor A4 of this embodiment, a protective layer 5 is formed on a metal layer 42.

[0056] In this embodiment, the protective layer 5 has a first portion 51 and a second portion 52. The first portion 51 is formed on the first surface 11. The dielectric layer 2, the first layer 31, and the second layer 32 are interposed between the first portion 51 and the first surface 11. The first portion 51 is in direct contact with the second layer 32.

[0057] Second portion 52 is formed on second surface 12. In the present embodiment, dielectric layer 2, first layer 31, second layer 32, graphite layer 41, and metal layer 42 are interposed between second portion 52 and second surface 12. Second portion 52 has a portion that is in direct contact with graphite layer 41 and a portion that is in direct contact with metal layer 42. The portion of graphite layer 41 that is not covered by second portion 52 is covered with metal layer 42.

[0058] 18, in the illustrated example, thickness t1, which is the maximum thickness from second surface 12 to the surface of second portion 52 (protective layer 5), is thinner than thickness t2, which is the maximum thickness from second surface 12 to the surface of metal layer 42. Thickness t1 corresponds to the first thickness in the present disclosure. Thickness t2 corresponds to the second thickness in the present disclosure.

[0059] 19 and 20 show a method for manufacturing the solid electrolytic capacitor A3. As shown in Fig. 19, in this embodiment, the step of forming the metal layer 42 is followed by the step of forming the protective layer 5.

[0060] 20 , after graphite layer 442 is formed, resin paste 500 is applied using dispenser Ds. In the illustrated example, resin paste 500 is applied onto substantially the entire surface of first surface 11 and onto a portion of second surface 12. Resin paste 500 applied onto first surface 11 contacts second layer 32. On second surface 12, a portion of graphite layer 41 is exposed from metal layer 42. Resin paste 500 applied onto second surface 12 contacts graphite layer 41 and metal layer 42.

[0061] The application of resin paste 500 onto second surface 12 may be performed intentionally, or may be the result of a portion of resin paste 500 extending onto second surface 12 in order to more reliably apply resin paste 500 to the entire surface of first surface 11. For this reason, the boundary between first surface 11 and second surface 12 is not limited to a configuration in which the entire length is covered with resin paste 500 (protective layer 5). It may also be a configuration in which only a portion of the boundary is covered with resin paste 500 (protective layer 5).

[0062] This embodiment also makes it possible to suppress damage to solid electrolyte layer 3. Furthermore, according to this embodiment, a portion of graphite layer 41 and a portion of metal layer 42 are covered with protective layer 5 (second portion 52). This makes it possible to suppress peeling and cracks from occurring at the end of graphite layer 41 and the end of metal layer 42.

[0063] 18, thickness t1, which is the maximum thickness from second surface 12 to the surface of second portion 52 (protective layer 5), is thinner than thickness t2, which is the maximum thickness from second surface 12 to the surface of metal layer 42. As a result, second portion 52 (protective layer 5) protects graphite layer 41 and metal layer 42, and providing second portion 52 can prevent the dimensions of the components including porous sintered body 1, dielectric layer 2, solid electrolyte layer 3, cathode layer 4, and protective layer 5 from unintentionally increasing.

[0064] The solid electrolytic capacitor and the method for manufacturing the solid electrolytic capacitor according to the present invention are not limited to the above-described embodiment. The specific configurations of the solid electrolytic capacitor and the method for manufacturing the solid electrolytic capacitor according to the present invention can be freely modified in various ways.

[0065] [Appendix 1] a porous sintered body having a first surface and including a valve metal; an anode wire protruding from the first surface and including a valve metal; a dielectric layer formed on the porous sintered body; a solid electrolyte layer formed on the dielectric layer; a cathode layer formed on the solid electrolyte layer, the solid electrolyte layer includes a first layer formed on the dielectric layer and a second layer formed on the first layer; a protective layer covering at least a portion of the first surface via the first layer; [Appendix 2] 2. The solid electrolytic capacitor according to claim 1, wherein the protective layer is in direct contact with the first layer. [Appendix 3] 2. The solid electrolytic capacitor according to claim 1, wherein the second layer is interposed between the first layer and the protective layer. [Appendix 4] the cathode layer includes a graphite layer formed on the solid electrolyte layer and a metal layer formed on the graphite layer, 4. The solid electrolytic capacitor according to claim 3, wherein the protective layer is in contact with the graphite layer. [Appendix 5] 5. The solid electrolytic capacitor according to claim 4, wherein the protective layer is in contact with the metal layer. [Appendix 6] the porous sintered body has a second surface that is spaced from the anode wire and connected to the first surface; the cathode layer is formed on the second surface; 6. The solid electrolytic capacitor according to claim 4, wherein the protective layer includes a first portion formed on the first surface and a second portion formed on the second surface. [Appendix 7] A solid electrolytic capacitor as described in Appendix 6, wherein a first thickness, which is the maximum thickness from the second surface to the surface of the second portion, is thinner than a second thickness, which is the maximum thickness from the second surface to the surface of the metal layer. [Appendix 8] 8. The solid electrolytic capacitor according to claim 1, wherein the protective layer contains at least one of a fluororesin, a silicone resin, and an acrylic resin. [Appendix 9] 9. The solid electrolytic capacitor according to claim 1, wherein a third thickness from the first surface to the surface of the protective layer is greater the closer to the anode wire. [Appendix 10] forming a porous sintered body containing a valve metal and having a first surface from which an anode wire containing a valve metal protrudes; forming a dielectric layer on the porous sintered body; forming a solid electrolyte layer on the dielectric layer; forming a cathode layer on the solid electrolyte layer; the step of forming the solid electrolyte layer includes the steps of forming a first layer on the dielectric layer and forming a second layer on the first layer; A method for manufacturing a solid electrolytic capacitor, comprising, after the step of forming the first layer, a step of forming a protective layer that covers at least a portion of the first surface. [Appendix 11] 11. The method for manufacturing a solid electrolytic capacitor according to claim 10, wherein the step of forming the protective layer is carried out before the step of forming the second layer. [Appendix 12] 11. The method for manufacturing a solid electrolytic capacitor according to claim 10, wherein the step of forming the protective layer is performed after the step of forming the second layer and before the step of forming the cathode layer. [Appendix 13] the step of forming the cathode layer includes the steps of forming a graphite layer on the solid electrolyte layer and forming a metal layer on the graphite layer; 11. The method for manufacturing a solid electrolytic capacitor according to claim 10, wherein the step of forming the protective layer is performed after the step of forming the graphite layer and before the step of forming the metal layer. [Appendix 14] 11. The method for manufacturing a solid electrolytic capacitor according to claim 10, wherein the step of forming the protective layer is carried out after the step of forming the cathode layer. [Appendix 15] 15. The method for manufacturing a solid electrolytic capacitor according to any one of claims 10 to 14, wherein the step of forming the first layer includes a chemical polymerization treatment or an electrolytic polymerization treatment. [Appendix 16] 16. The method for manufacturing a solid electrolytic capacitor according to any one of claims 10 to 15, wherein the step of forming the second layer includes a chemical polymerization treatment or an electrolytic polymerization treatment. [Appendix 17] 17. The method for manufacturing a solid electrolytic capacitor according to any one of claims 10 to 16, wherein the step of forming the protective layer comprises applying a paste material that will become the protective layer onto the first surface using a dispenser. [Appendix 18] 18. The method for manufacturing a solid electrolytic capacitor according to any one of claims 10 to 17, wherein the protective layer contains at least one of a fluororesin, a silicone resin, and an acrylic resin. [Explanation of symbols]

[0066] A1, A2, A3, A4: Solid electrolytic capacitors 1: Porous sintered body 2: Dielectric layer 3: Solid electrolyte layer 4: Cathode layer 5:Protective layer 6: Anode conductive member 7: Cathode conductive member 8: Sealing resin 10: Anode wire 11: 1st page 12:Second side 31: 1st layer 32: 2nd layer 41: Graphite layer 42: Metal layer 51: Part 1 52: Part 2 61:Terminal section 62: Relay section 79: Conductive bonding material 100: Intermediate product 200: Chemical liquid 310, 320: Reaction solution 442: graphite layer 500: Resin paste Ds: Dispenser t1, t2, t3: thickness

Claims

1. A solid electrolytic capacitor, a porous sintered body containing a valve metal and having a first surface and a second surface connected to the first surface; an anode wire protruding from the first surface and comprising a valve metal; a dielectric layer formed on the porous sintered body; a solid electrolyte layer formed on the dielectric layer; a cathode layer formed on the solid electrolyte layer, the solid electrolyte layer includes a first layer formed on the dielectric layer and a second layer formed on the first layer, a protective layer covering at least a portion of the first surface via the first layer; the protective layer has a first portion formed on the first surface and a second portion formed only on a portion of the second surface, a first portion of the protective layer having a thickness from the first surface to a surface of the first portion of the protective layer, the thickness of the first portion of the protective layer increasing as it approaches the anode wire.

2. The solid electrolytic capacitor according to claim 1 , wherein the protective layer is in direct contact with the first layer.

3. The solid electrolytic capacitor according to claim 1 , wherein the second layer is interposed between the first layer and the protective layer.

4. the cathode layer includes a graphite layer formed on the solid electrolyte layer and a metal layer formed on the graphite layer, The solid electrolytic capacitor according to claim 3 , wherein the protective layer is in contact with the graphite layer.

5. The solid electrolytic capacitor according to claim 4 , wherein the protective layer is in contact with the metal layer.

6. the second surface is spaced from the anode wire; 6. The solid electrolytic capacitor according to claim 4, wherein the cathode layer is formed on the second surface.

7. 7. The solid electrolytic capacitor according to claim 4, wherein a first thickness, which is the maximum thickness from the second surface to the surface of the second portion, is thinner than a second thickness, which is the maximum thickness from the second surface to the surface of the metal layer.

8. 8. The solid electrolytic capacitor according to claim 1, wherein said protective layer contains at least one of a fluororesin, a silicone resin, and an acrylic resin.

9. A method for manufacturing a solid electrolytic capacitor, comprising: forming a porous sintered body containing a valve metal, having a first surface and a second surface connected to the first surface, and an anode wire containing the valve metal protruding from the first surface; forming a dielectric layer on the porous sintered body; forming a solid electrolyte layer on the dielectric layer; forming a cathode layer on the solid electrolyte layer; the step of forming the solid electrolyte layer includes the steps of forming a first layer on the dielectric layer and forming a second layer on the first layer; forming a protective layer that covers at least a portion of the first surface after the step of forming the first layer; the protective layer has a first portion formed on the first surface and a second portion formed only on a portion of the second surface, a first portion of the protective layer having a thickness from the first surface to a surface of the first portion of the protective layer, the thickness of the first portion of the protective layer increasing as it approaches the anode wire.

10. The method for manufacturing a solid electrolytic capacitor according to claim 9 , wherein the step of forming the protective layer is performed before the step of forming the second layer.

11. The method for manufacturing a solid electrolytic capacitor according to claim 9 , wherein the step of forming the protective layer is performed after the step of forming the second layer and before the step of forming the cathode layer.

12. the step of forming the cathode layer includes the steps of forming a graphite layer on the solid electrolyte layer and forming a metal layer on the graphite layer; The method for manufacturing a solid electrolytic capacitor according to claim 9 , wherein the step of forming the protective layer is performed after the step of forming the graphite layer and before the step of forming the metal layer.

13. The method for manufacturing a solid electrolytic capacitor according to claim 9 , wherein the step of forming the protective layer is performed after the step of forming the cathode layer.

14. 14. The method for manufacturing a solid electrolytic capacitor according to claim 9, wherein the step of forming the first layer includes a chemical polymerization treatment or an electrolytic polymerization treatment.

15. 15. The method for manufacturing a solid electrolytic capacitor according to claim 9, wherein the step of forming the second layer includes a chemical polymerization treatment or an electrolytic polymerization treatment.

16. 16. The method for manufacturing a solid electrolytic capacitor according to claim 9, wherein the step of forming the protective layer comprises applying a paste material that will become the protective layer onto the first surface using a dispenser.

17. 17. The method for manufacturing a solid electrolytic capacitor according to claim 9, wherein the protective layer contains at least one of a fluororesin, a silicone resin, and an acrylic resin.

18. forming a porous sintered body containing a valve metal and having a first surface from which an anode wire containing a valve metal protrudes; forming a dielectric layer on the porous sintered body; forming a solid electrolyte layer on the dielectric layer; forming a cathode layer on the solid electrolyte layer; the step of forming the solid electrolyte layer includes the steps of forming a first layer on the dielectric layer and forming a second layer on the first layer; forming a protective layer that covers at least a portion of the first surface after the step of forming the first layer; The method for manufacturing a solid electrolytic capacitor includes forming the protective layer before forming the second layer.

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