Method for manufacturing solid electrolytic capacitor

Abstract

A method for manufacturing a solid electrolytic capacitor 300 includes a solid electrolytic capacitor element 1 having: a valve-action metal base-body 10 having an anode terminal region 31 and a cathode formation region 32; a dielectric layer 20 formed on the valve-action metal base-body 10; a solid electrolyte layer 40 formed on the dielectric layer 20; and a current collector layer 50 formed on the solid electrolyte layer 40. The method includes: a step for forming a masking region 61 composed of a masking member 60 for partitioning the anode terminal region 31 and the cathode formation region 32 and insulating the valve-action metal base-body 10 from the counter electrode on the valve-action metal base-body 10; a step for providing, on the surface of the masking region 61, a water-repellent layer 70 in at least a part of an anode-side masking region 65 located closer to the anode terminal region 31 side than a cathode-side masking region 63 without providing the water-repellent layer 70 in the cathode-side masking region 63, which is a predetermined region including an end part on the cathode formation region side; and a step for forming the solid electrolyte layer 40 by applying a raw material liquid containing a material forming the solid electrolyte layer 40 from the cathode formation region 32 to the cathode-side masking region 63 of the masking region 61.

Description

Manufacturing method for solid electrolytic capacitors

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

[0002] Patent Document 1 discloses a method for producing a solid electrolytic capacitor element by forming a dielectric layer made of an oxide film on the surface of a roughened valve metal substrate, then forming a resist layer to separate the anode portion from the cathode portion, and sequentially forming a solid electrolyte layer and a current collecting layer made of a carbon paste layer and a silver paste layer on the dielectric layer excluding the anode portion.

[0003] JP 2009-158692 A

[0004] Known methods for forming a solid electrolyte layer include using a precursor solution containing materials for forming the solid electrolyte layer. Specifically, known methods include applying a polymerization solution containing monomers that will form the solid electrolyte layer through a chemical polymerization reaction to form a polymerized conductive polymer film on the surface of a dielectric layer, or depositing polymer particles in which polymerizable monomers have been prepolymerized on the surface of a dielectric layer to form a conductive polymer film. The solid electrolytic capacitor element described in Patent Document 1 has a resist layer (hereinafter referred to as a masking member) that separates the anode portion (hereinafter referred to as the anode terminal region) and the cathode portion (hereinafter referred to as the cathode formation region) of a valve metal substrate. In such a configuration with a masking member, for example, when applying the precursor solution to the cathode formation region, the precursor solution is applied to the surface of the masking member so as to contact the edge of the masking member facing the cathode formation region to maximize the area of ​​the cathode formation region. This precursor solution tends to spread over the surface of the masking member and may even extend beyond the masking member and reach the anode terminal region. If the raw material solution reaches the valve metal substrate on the anode terminal area side, there is a risk of LC failure (leakage current failure) occurring.

[0005] The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor that can prevent the occurrence of LC defects in a method for manufacturing a solid electrolytic capacitor that uses a method of providing a masking member to form a solid electrolyte layer in a cathode formation region.

[0006] The present invention provides a method for manufacturing a solid electrolytic capacitor comprising a solid electrolytic capacitor element having a valve metal substrate having an anode terminal region and a cathode formation region, a dielectric layer formed on the valve metal substrate, a solid electrolyte layer formed on the dielectric layer, and a current collecting layer formed on the solid electrolyte layer, the method comprising the steps of: forming a masking region on the valve metal substrate to separate the anode terminal region from the cathode formation region and to insulate the valve metal substrate from a counter electrode; providing a water-repellent layer on at least a portion of the anode-side masking region located closer to the anode terminal region than the cathode-side masking region, while not providing a water-repellent layer in a cathode-side masking region that is a predetermined region on the surface of the masking region and that includes an end portion on the cathode formation region side; and applying a raw material solution containing a material for forming the solid electrolyte layer from the cathode formation region to the cathode-side masking region of the masking region to form the solid electrolyte layer.

[0007] According to the present invention, it is possible to provide a method for manufacturing a solid electrolytic capacitor that can prevent the occurrence of LC defects in a method for forming a solid electrolyte layer in a cathode formation region by providing a masking member.

[0008] FIG. 1 is a cross-sectional view schematically showing an example of a solid electrolytic capacitor element. FIG. 2 is a perspective view schematically showing an example of a solid electrolytic capacitor including the solid electrolytic capacitor element shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line II of the solid electrolytic capacitor shown in FIG. 2. FIG. 4A is a plan view schematically showing an example of a valve metal substrate on which a dielectric layer and a masking region are formed. FIG. 4B is a cross-sectional view taken along line A-A of FIG. 4A. FIG. 5A is a plan view schematically showing an example of an element on which a water-repellent layer is formed. FIG. 5B is a cross-sectional view taken along line B-B of FIG. 5A. FIG. 6 is a cross-sectional view schematically showing an example of an element on which a solid electrolyte layer is formed. FIG. 7 is a cross-sectional view schematically showing an example of an element on which a conductive layer is formed. FIG. 8 is a cross-sectional view schematically showing another example of an element on which a water-repellent layer is formed. FIG. 9 is a cross-sectional view schematically showing another example of an element on which a water-repellent layer is formed. Fig. 10 is a cross-sectional view schematically showing an example of a state in which a solid electrolyte layer and a current collecting layer are formed on the element shown in Fig. 9 and the water-repellent layer is peeled off. Fig. 11 is a cross-sectional view schematically showing an example of an element provided with an acrylic resin layer and a water-repellent layer. Fig. 12 is a cross-sectional view schematically showing an example of a state in which a solid electrolyte layer and a current collecting layer are formed on the element shown in Fig. 11 and the acrylic resin layer and the water-repellent layer are peeled off. Fig. 13 is a cross-sectional view schematically showing another example of an element provided with an acrylic resin layer and a water-repellent layer.

[0009] The method for manufacturing a solid electrolytic capacitor of the present invention will be described below. First, examples of the configuration of the solid electrolytic capacitor, which is the object to be manufactured by the method for manufacturing a solid electrolytic capacitor of the present invention, and the configuration of the solid electrolytic capacitor element that constitutes the solid electrolytic capacitor will be described. Note that the object to be manufactured by the method for manufacturing a solid electrolytic capacitor of the present invention is not limited to the solid electrolytic capacitor and solid electrolytic capacitor element described below.

[0010] Furthermore, the present invention is not limited to the following configurations, and can be appropriately modified and applied within the scope of the present invention. Note that the present invention also includes a combination of two or more of the individual desirable configurations described below.

[0011] Fig. 1 is a cross-sectional view showing a schematic example of a solid electrolytic capacitor element. The solid electrolytic capacitor element 1 shown in Fig. 1 has a valve metal substrate 10, a dielectric layer 20 formed on the valve metal substrate 10, a solid electrolyte layer 40 formed on the dielectric layer 20, and a current collecting layer 50 formed on the solid electrolyte layer 40.

[0012] In the solid electrolytic capacitor element 1, a masking region 61 made of a masking member 60 is provided on the dielectric layer 20 to separate the anode terminal region 31 and the cathode formation region 32 and to insulate the valve metal substrate 10 from the counter electrode. In Fig. 1, the three regions, the anode terminal region 31, the masking region 61, and the cathode formation region 32, are respectively indicated by double-headed arrows. With the masking region 61 as a boundary, the side of the anode end 33 where the solid electrolyte layer 40 is not provided is the anode terminal region 31, and the side of the cathode end 34 where the solid electrolyte layer 40 is provided is the cathode formation region 32.

[0013] The valve metal substrate 10 is made of a valve metal, such as an elemental metal such as aluminum, tantalum, niobium, titanium, or zirconium, or an alloy containing these metals. The main surface of the valve metal substrate 10 is preferably porous having pores. By making the main surface of the valve metal substrate 10 porous, the surface area of ​​the valve metal substrate 10 is increased. Note that the valve metal substrate 10 is not limited to a case where both the front and back surfaces are porous, and only one of the front and back surfaces may be porous.

[0014] The dielectric layer 20 is preferably formed of an oxide film provided on the surface of the valve metal substrate. For example, the dielectric layer 20 is preferably formed of an aluminum oxide. The aluminum oxide is formed by anodizing the surface of the valve metal substrate 10, as described below.

[0015] A masking region 61 made of a masking member 60 is provided on the valve metal substrate 10. The masking member 60 is preferably provided so as to fill a plurality of pores (recesses) of the porous valve metal substrate 10.

[0016] The masking member 60 is formed by applying a mask material such as a composition containing an insulating resin. Examples of insulating resins include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene-perfluoroalkylvinylether copolymer, etc.), a composition consisting of soluble polyimidesiloxane and epoxy resin, polyimide resin, polyamideimide resin, and derivatives or precursors thereof.

[0017] The solid electrolyte layer 40 is provided on the dielectric layer 20 in the cathode formation region 32. The solid electrolyte layer 40 is preferably provided so as to fill a plurality of pores (recesses) of the porous valve metal substrate 10.

[0018] Examples of materials that can be used to form the solid electrolyte layer 40 include conductive polymers such as polypyrroles, polythiophenes, and polyanilines. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene), also known as PEDOT, is particularly preferred. The conductive polymers may also contain a dopant such as polystyrene sulfonate (PSS).

[0019] The solid electrolyte layer 40 is formed by applying a raw material solution containing a material for forming the solid electrolyte layer 40 so as to cover the cathode formation region partitioned by the masking member 60. Here, the raw material solution includes a liquid containing a polymerizable monomer, a dispersion of polymer fine particles in which the polymerizable monomer has been pre-polymerized, or the like. That is, for example, a liquid containing a polymerizable monomer such as PEDOT and PSS may be used and polymerized on the surface of the dielectric layer 20 to form a film of a conductive polymer such as PEDOT-PSS. Alternatively, for example, a film of a conductive polymer may be formed by depositing polymer fine particles such as PEDOT-PSS in which polymerizable monomers such as PEDOT and PSS have been pre-polymerized on the surface of the dielectric layer 20.

[0020] 1 shows a carbon layer 51 and a metal layer 52 as the current collecting layer 50. The carbon layer 51 can be formed by applying a carbon paste, and the metal layer 52 can be formed by applying a conductive paste such as a silver paste.

[0021] Fig. 2 is a perspective view schematically showing an example of a solid electrolytic capacitor including the solid electrolytic capacitor element shown in Fig. 1. Fig. 3 is a cross-sectional view taken along line II of the solid electrolytic capacitor shown in Fig. 2.

[0022] 2 and 3 , the solid electrolytic capacitor 300 has a substantially rectangular parallelepiped outer shape and includes an outer casing 310, a first external electrode 320, a second external electrode 330, and a capacitor element assembly 340 including a plurality of solid electrolytic capacitor elements 1.

[0023] The exterior body 310 has a substantially rectangular parallelepiped outer shape. A capacitor element assembly 340 including a plurality of solid electrolytic capacitor elements 1 is provided inside the exterior body 310. The exterior body 310 has a first main surface 310a and a second main surface 310b facing each other in the height direction T, a first side surface 310c and a second side surface 310d facing each other in the width direction W, and a first end surface 310e and a second end surface 310f facing each other in the length direction L. Note that a single solid electrolytic capacitor element 1 may be provided inside the exterior body 310.

[0024] The capacitor element assembly 340 includes a plurality of solid electrolytic capacitor elements 1 (solid electrolytic capacitor element 1a, solid electrolytic capacitor element 1b, solid electrolytic capacitor element 1c, solid electrolytic capacitor element 1d) and a conductive member 319. In the embodiment shown in Fig. 3, the number of solid electrolytic capacitor elements constituting the capacitor element assembly 340 is four, but the number of solid electrolytic capacitor elements constituting the capacitor element assembly is not particularly limited.

[0025] The plurality of solid electrolytic capacitor elements 1 are stacked such that the dimension of the plurality of solid electrolytic capacitor elements 1 in the stacking direction on the second end face 310f side is larger than the dimension of the plurality of solid electrolytic capacitor elements 1 in the stacking direction on the first end face 310e side. In other words, the plurality of solid electrolytic capacitor elements 1 are arranged so as to expand in the thickness direction from the first end face side toward the second end face side in side view.

[0026] The anode terminal region of each of the valve metal substrates in the plurality of solid electrolytic capacitor elements 1 is connected to the first external electrode 320. It is preferable that the valve metal substrate is joined by resistance welding in the anode terminal region, and it is also preferable that the valve metal substrate is joined to the first external electrode in the anode terminal region by resistance welding.

[0027] The conductive layers of the multiple solid electrolytic capacitor elements 1 are electrically and physically connected by the conductive member 319, and these are electrically and physically connected to the second external electrode 330. The conductive member 319 is preferably an electrode paste containing nickel, silver, or copper as a main component, for example. Note that even without using the conductive member 319, if conductivity equal to or higher than the desired conductivity can be obtained between the multiple solid electrolytic capacitor elements 1, between the solid electrolytic capacitor elements 1b, 1c and the second external electrode 330, etc., the conductive member 319 can be omitted.

[0028] The first external electrode 320 and the second external electrode 330 are preferably formed from a metal material that is easy to bend and has high conductivity. The first external electrode 320 and the second external electrode 330 are formed from, for example, a material cut out from a metal plate. Note that the first external electrode 320 and the second external electrode 330 may be made of the same material or different materials.

[0029] The exterior body 310 is mainly made of resin and may contain a filler. Preferred examples of the resin include epoxy resin, phenol resin, polyimide resin, silicone resin, polyamide resin, and liquid crystal polymer. The resin may be in either solid or liquid form. It is preferable that the corners are rounded by barrel polishing after resin sealing. Preferred examples of the filler include silica particles, alumina particles, and metal particles. The maximum diameter of the filler is preferably 30 μm or more and 40 μm or less. A material containing silica particles in a solid epoxy resin and phenol resin is more preferred.

[0030] First Embodiment Hereinafter, an example of an embodiment of the method for manufacturing a solid electrolytic capacitor of the present invention will be described, taking as an example the case of manufacturing a solid electrolytic capacitor including the solid electrolytic capacitor element as described above.

[0031] The method for manufacturing a solid electrolytic capacitor of the present invention includes a step of forming a masking region made of a masking material on a valve metal substrate to separate an anode terminal region and a cathode formation region and to insulate the valve metal substrate from a counter electrode.

[0032] FIG. 4A is a plan view schematically illustrating an example of a valve metal substrate on which a dielectric layer and a masking region are formed, and FIG. 4B is a cross-sectional view taken along line A-A in FIG. 4A . A chemically formed foil on which an aluminum oxide is formed as the dielectric layer 20 can be used as the valve metal substrate 10. When a masking region 61 consisting of a masking member 60 is provided on this valve metal substrate 10, the masking region 61 is formed on the dielectric layer 20. Alternatively, a metal foil without a dielectric layer 20 can be used as the valve metal substrate 10, and a masking region 61 consisting of the masking member 60 can be provided on the metal foil. An anodizing treatment can then be performed to form an oxide film that will become the dielectric layer 20 on the surface of the valve metal substrate 10. In this case, the dielectric layer 20 is not present directly below the masking member 60.

[0033] In the method for manufacturing a solid electrolytic capacitor of the present invention, the step of forming a masking region made of a masking member on a valve metal substrate is included whether the masking region is formed on the dielectric layer of a valve metal substrate that has a dielectric layer thereon or whether the masking region is formed on a valve metal substrate that does not have a dielectric layer thereon. Furthermore, in the solid electrolytic capacitor element to be manufactured, a dielectric layer may or may not be present directly below the masking member.

[0034] The masking region can be formed by applying a solution containing a resin that will become the masking member. The solution can be applied by methods such as screen printing, roller transfer, dispenser application, and inkjet printing.

[0035] 4A, the masking region 61 is preferably provided in a strip shape along the short direction of the valve metal substrate. The masking region 61 defines the positions of the anode terminal region 31 and the cathode formation region 32. Typically, in order to increase the capacitance of the capacitor, the masking region 61 is positioned so that the area of ​​the cathode formation region 32 is large.

[0036] In the method for manufacturing a solid electrolytic capacitor of the present invention, a water-repellent layer is not provided in a cathode-side masking region, which is a predetermined region on the surface of the masking region that includes an end portion on the cathode formation region side, and a water-repellent layer is provided in at least a portion of the anode-side masking region that is located closer to the anode terminal region than the cathode-side masking region.

[0037] Fig. 5A is a plan view schematically showing an example of an element provided with a water-repellent layer, and Fig. 5B is a cross-sectional view taken along line B-B in Fig. 5A. In the step of providing the water-repellent layer, the water-repellent layer is provided on a portion of the surface of the masking region. The water-repellent layer 70 is not provided on a cathode-side masking region 63, which is a predetermined region of the surface of the masking region 61 that includes an end 62 on the cathode formation region side, but the water-repellent layer 70 is provided on at least a portion of an anode-side masking region 65 that is located closer to the anode terminal region 31 than the cathode-side masking region 63.

[0038] By providing a water-repellent layer in a region of the surface of the masking region that does not include the end portion on the cathode formation region side, a region where the water-repellent layer is provided and a region where the water-repellent layer is not provided are separated. As a result, the region where the water-repellent layer is not provided and that includes the end portion on the cathode formation region side is defined as the cathode-side masking region. The region closer to the anode terminal region than the cathode-side masking region is defined as the anode-side masking region. The region of the anode-side masking region adjacent to the cathode-side masking region is defined as the region where the water-repellent layer is provided.

[0039] The water-repellent layer 70 is preferably provided in a strip shape along the short direction of the valve metal substrate as shown in Fig. 5A. In the embodiment shown in Fig. 5A and Fig. 5B, the water-repellent layer 70 is provided on the surface of the masking region 61 in a region including the end 64 on the anode terminal region side. In other words, the water-repellent layer 70 is provided over the entire anode-side masking region 65.

[0040] The water-repellent layer can be formed by applying a solution containing a water-repellent agent. A protective layer is first formed on a predetermined area of ​​the surface of the masking region, including the end of the masking region on the cathode formation region side, to prevent the water-repellent agent from coming into contact with the predetermined area. The solution can be applied by, for example, screen printing, roller transfer, dispenser application, inkjet printing, or other methods. Furthermore, the viscosity of the solution containing the water-repellent agent is preferably higher than the viscosity of the solution containing the resin that will form the masking member. For example, when the viscosity of the solution containing the resin that will form the masking member is 5 to 15 Pa·s, the viscosity of the solution containing the water-repellent agent is preferably 50 to 100 Pa·s, and more preferably 60 to 90 Pa·s.

[0041] The water repellent may be an epoxy resin, a polyester resin, a silicone, or the like, and preferably contains silicone. As the silicone, it is preferable to use a modified silicone in which an appropriate substituent has been introduced to improve the water repellency.

[0042] In a first embodiment of the method for manufacturing a solid electrolytic capacitor of the present invention, a step of forming a solid electrolyte layer is performed by applying a polymerization solution containing a monomer that will become a solid electrolyte layer by a chemical polymerization reaction from the cathode formation region to the cathode-side masking region of the masking region.

[0043] Fig. 6 is a cross-sectional view schematically showing an example of an element on which a solid electrolyte layer is formed. The position of the cross-sectional view corresponds to the position of Fig. 5B. Fig. 6 shows that the solid electrolyte layer 40 is formed on the entire dielectric layer 20 in the cathode formation region 32, and the dielectric layer 20 is not exposed in the cathode formation region 32. The solid electrolyte layer 40 is also formed in the cathode-side masking region 63. The solid electrolyte layer 40 is not formed in the anode-side masking region 65 or the anode terminal region 31.

[0044] In the process of forming the solid electrolyte layer, a polymerization liquid containing a monomer that will become the solid electrolyte layer through a chemical polymerization reaction is used. The polymerization liquid preferably contains a monomer and a solvent that will become the solid electrolyte layer through a chemical polymerization reaction. Examples of conductive polymers that constitute the solid electrolyte layer include conductive polymers such as polypyrroles, polythiophenes, and polyanilines. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene), also known as PEDOT, is particularly preferred. Therefore, the monomer contained in the polymerization liquid is preferably a monomer that will become the above-mentioned conductive polymer through a chemical polymerization reaction, such as pyrrole, thiophene, or aniline. Among these, 3,4-ethylenedioxythiophene is more preferred. The solvent contained in the polymerization liquid may be an aqueous solvent or an alcohol-based solvent, with an alcohol-based solvent being preferred.

[0045] The polymerization liquid may further contain a dopant, such as aromatic sulfonic acids and their salts, such as polystyrene sulfonic acid (PSS) and anthraquinone sulfonic acid (AQS) salts.

[0046] The polymerization liquid may contain an oxidizing agent that acts as a polymerization initiator to polymerize the above-mentioned monomers. Examples of the oxidizing agent include ammonium persulfate, iron p-toluenesulfonate (PTSA), etc.

[0047] In the process of forming the solid electrolyte layer, the polymerization liquid is applied from the cathode formation region to the cathode-side masking region of the masking region. Specifically, the polymerization liquid is applied so as to straddle the edge of the surface of the masking region on the cathode formation region side. In this manner, the solid electrolyte layer is reliably formed on the dielectric layer in the cathode formation region. The polymerization liquid that spreads from the cathode-side masking region of the masking region toward the anode terminal region is repelled by the water-repellent layer and does not spread to the anode-side masking region. This prevents the polymerization liquid from reaching the anode terminal region, thereby preventing LC defects.

[0048] As described above, the presence of the cathode-side masking region where no water-repellent layer is provided ensures that a solid electrolyte layer is formed on the dielectric layer in the cathode formation region, and the provision of the water-repellent layer adjacent to the cathode-side masking region prevents the polymerization solution from reaching the anode terminal region.

[0049] To ensure that a solid electrolyte layer is formed on the dielectric layer in the cathode formation region, it is preferable to widen the cathode-side masking region where the water-repellent layer is not provided. On the other hand, to ensure that the polymerization solution does not reach the anode terminal region, it is preferable to form the water-repellent layer over a wide area. Therefore, for example, it is preferable that the width of the masking region along the longitudinal direction of the valve metal substrate is 100%, and that the width of the cathode-side masking region is 10% or more but less than 100%.

[0050] After the application of the polymerization liquid, drying may be carried out as necessary. The temperature for drying may be 25° C. or higher and 100° C. or lower. Furthermore, natural drying may be used instead of forced drying using an oven or the like. Furthermore, the film may be in a semi-dried state.

[0051] Next, a step of forming a conductive layer on the solid electrolyte layer is performed. Fig. 7 is a cross-sectional view schematically showing an example of an element on which a conductive layer has been formed. Fig. 7 shows a state in which a current collecting layer 50 (carbon layer 51 and metal layer 52) is provided on the solid electrolyte layer 40. In this step, a carbon paste and a conductive paste are applied to the solid electrolyte layer to form the carbon layer and the metal layer in predetermined regions, thereby forming the conductive layer.

[0052] Next, a step of peeling off the water-repellent layer is performed. The water-repellent layer is preferably peeled off and removed after the formation of the solid electrolyte layer or the conductive layer. The method for peeling off the water-repellent layer is not particularly limited, and physical peeling can be used. By peeling off the water-repellent layer, a solid electrolytic capacitor element having a configuration as shown in FIG. 1 is obtained.

[0053] A plurality of solid electrolytic capacitor elements are stacked, and the anode terminal regions of the valve metal substrates are joined by resistance welding or other methods. They are then joined to a lead frame that serves as the first external electrode. The cathode-side conductive layer is electrically and physically connected by a conductive member. They are then joined to a lead frame that serves as the second external electrode. The capacitor element assembly including the plurality of solid electrolytic capacitor elements is then sealed in an exterior housing, and the first and second external electrodes are extended from the exterior housing, thereby obtaining a solid electrolytic capacitor.

[0054] Second Embodiment Another embodiment of the method for manufacturing a solid electrolytic capacitor according to the present invention will be described below. In this embodiment, a water-repellent layer is provided in a part of the anode-side masking region, and a region of the anode-side masking region that is located closer to the anode terminal region than the region where the water-repellent layer is provided is defined as a region of the anode-side masking region where the water-repellent layer is not provided.

[0055] Fig. 8 is a cross-sectional view schematically showing another example of an element provided with a water-repellent layer. The position of the cross-sectional view corresponds to the position of Fig. 5B. In the embodiment shown in Fig. 8, the water-repellent layer 70 is not provided in a region of the surface of the masking region 61, including the end 64 on the anode terminal region side. In other words, the water-repellent layer 70 is not provided in a part of the anode-side masking region 65.

[0056] 8 , the masking region 61 is divided into three regions from an end 62 of the masking region on the cathode formation region side toward an end 64 of the masking region on the anode terminal region side. That is, the masking region is divided into a cathode-side masking region 63 where the water-repellent layer 70 is not provided, a region 65a of the anode-side masking region 65 where the water-repellent layer 70 is provided, and a region 65b of the anode-side masking region 65 where the water-repellent layer 70 is not provided.

[0057] In this embodiment, the presence of the cathode-side masking region where no water-repellent layer is provided ensures that a solid electrolyte layer is formed on the dielectric layer in the cathode formation region, and the provision of the water-repellent layer adjacent to the cathode-side masking region prevents the polymerization solution from reaching the anode terminal region. By adjusting the region to which the solution containing the water-repellent agent is applied, the method for manufacturing a solid electrolytic capacitor of this embodiment can be carried out.

[0058] Third Embodiment Another embodiment of the method for manufacturing a solid electrolytic capacitor of the present invention will be described below. In this embodiment, a water-repellent layer is provided on a valve metal substrate in the anode terminal region. In this embodiment, the step of providing a water-repellent layer on a valve metal substrate includes both the case where a water-repellent layer is provided on a dielectric layer of a valve metal substrate provided with a dielectric layer and the case where a water-repellent layer is provided on a valve metal substrate not provided with a dielectric layer.

[0059] FIG. 9 is a cross-sectional view schematically illustrating another example of an element provided with a water-repellent layer. The position in the cross-sectional view corresponds to the position in FIG. 5B . In the embodiment shown in FIG. 9 , the water-repellent layer 70 is continuously provided from the masking region 61 to the anode terminal region 31. Furthermore, in the anode terminal region 31, the water-repellent layer 70 penetrates into the pores of the valve metal substrate 10. In FIG. 9 and other drawings, the state in which the water-repellent layer 70 penetrates into the pores of the valve metal substrate 10 is shown by overlapping the hatching of the water-repellent layer 70 with the hatching of the dielectric layer 20. If the water-repellent layer is provided over a wide area including the anode terminal region, when the polymerization liquid is applied widely from the cathode formation region to the entire masking region, even if the polymerization liquid comes into contact with the anode terminal region, a solid electrolyte layer will not be formed in the anode terminal region. This increases the tolerance for setting conditions for the manufacturing process.

[0060] When a water-repellent layer is provided in the anode terminal area, the water-repellent layer may be provided over the entire anode terminal area, or may be provided only in a portion of the anode terminal area. When a water-repellent layer is provided in a portion of the anode terminal area, the water-repellent layer is provided only in a predetermined area continuous from the masking area. Furthermore, the water-repellent layer is not provided in the area of ​​the anode terminal area on the anode end side.

[0061] The presence of an insulating material such as a water-repellent layer in the anode terminal area can hinder resistance welding. However, the area where no water-repellent layer is provided and the valve metal substrate is exposed is suitable for resistance welding, and therefore, this area can be used to perform resistance welding and produce a solid electrolytic capacitor.

[0062] In this specification, resistance welding of an exposed region of a valve action metal substrate includes resistance welding of a portion of the valve action metal substrate on which a dielectric layer is provided, and resistance welding of a portion on which no dielectric layer is provided. Because the thickness of the dielectric layer is thin, the presence or absence of a dielectric layer has little effect on the workability of resistance welding.

[0063] In this embodiment, after the application of the polymerization solution, a step of peeling off the water-repellent layer provided in the anode terminal region is preferably performed. Figure 10 is a cross-sectional view schematically illustrating an example of the state after forming a solid electrolyte layer and a current collecting layer on the element shown in Figure 9 and peeling off the water-repellent layer. When the water-repellent layer 70 is formed in the anode terminal region 31, the water-repellent layer 70 penetrates into the pores of the valve metal substrate 10 that constitutes the anode terminal region 31. When the water-repellent layer 70 is peeled off from the surface of the valve metal substrate 10, a portion of the water-repellent layer 70 remains in the pores. The state in which a portion of the water-repellent layer 70 remains in the pores is shown by overlapping the hatching of the water-repellent layer 70 with the hatching of the dielectric layer 20. Therefore, for solid electrolytic capacitors manufactured with a water-repellent layer provided in the anode terminal region, it is possible to confirm that the solid electrolytic capacitor was manufactured using the water-repellent layer by detecting elements (e.g., Si) derived from the water-repellent agent that constitutes the water-repellent layer using an analytical method such as elemental analysis of the surface of the anode terminal region to detect elements (e.g., Si) derived from the water-repellent agent that constitutes the water-repellent layer.

[0064] On the other hand, since the water-repellent layer formed in the masking area does not remain after the water-repellent layer is peeled off, it is difficult to confirm that a solid electrolytic capacitor was manufactured using a water-repellent layer from a solid electrolytic capacitor manufactured with the water-repellent layer only in the masking area.

[0065] Fourth Embodiment Another embodiment of the method for manufacturing a solid electrolytic capacitor of the present invention will be described below. In this embodiment, an acrylic resin layer is provided on a valve metal substrate in the anode terminal region, and a water-repellent layer is also provided on the acrylic resin layer. In this embodiment, the step of providing an acrylic resin layer on a valve metal substrate includes both the case where an acrylic resin layer is provided on a dielectric layer of a valve metal substrate provided with a dielectric layer and the case where an acrylic resin layer is provided on a valve metal substrate not provided with a dielectric layer.

[0066] Fig. 11 is a cross-sectional view schematically illustrating an example of an element provided with an acrylic resin layer and a water-repellent layer. The position in the cross-sectional view corresponds to the position in Fig. 5B. In the embodiment shown in Fig. 11, an acrylic resin layer 80 is provided in a portion of the anode terminal region 31. The water-repellent layer 70 is provided continuously from the masking region 61 onto the acrylic resin layer 80 and over a region of the anode terminal region 31 closer to the anode end 33 than the acrylic resin layer 80.

[0067] The position where the water-repellent layer is provided is the same as in the third embodiment, and therefore, the tolerance for setting conditions in the manufacturing process can be increased, as in the third embodiment.

[0068] In this embodiment, after applying the polymerization liquid, it is preferable to perform a step of peeling off the acrylic resin layer and the water-repellent layer provided on the acrylic resin layer, and then a step of welding a plurality of solid electrolytic capacitor elements by resistance welding the surface of the valve metal base exposed by peeling off the acrylic resin layer.

[0069] FIG. 12 is a cross-sectional view schematically illustrating an example of the state after forming a solid electrolyte layer and a current collecting layer on the element shown in FIG. 11 and peeling off the acrylic resin layer and water-repellent layer. The acrylic resin does not penetrate into the pores of the valve metal substrate constituting the anode terminal region. Therefore, the acrylic resin layer and water-repellent layer do not remain in the pores where the acrylic resin layer is peeled off, exposing the valve metal substrate. On the other hand, in the region where the acrylic resin layer is not provided but the water-repellent layer is provided in the anode terminal region, a portion of the water-repellent layer remains in the pores after peeling off the water-repellent layer. While insulating materials such as the water-repellent layer and acrylic resin layer remaining in the pores can hinder resistance welding, the region where the valve metal substrate is exposed is suitable for resistance welding. Therefore, by peeling off the acrylic resin layer, resistance welding can be performed using the region where the valve metal substrate is exposed, thereby producing a solid electrolytic capacitor. A dielectric layer may or may not be provided on the surface of the valve metal substrate where resistance welding is performed.

[0070] Furthermore, if a portion of the water-repellent layer remains in the pores, it can be confirmed from the solid electrolytic capacitor that the capacitor was manufactured using the water-repellent layer.

[0071] In this embodiment, the acrylic resin layer may be provided over the entire anode terminal region. FIG. 13 is a cross-sectional view schematically illustrating another example of an element provided with an acrylic resin layer and a water-repellent layer. The position of the cross-sectional view corresponds to the position of FIG. 5B . In the embodiment shown in FIG. 13 , an acrylic resin layer 80 is provided over the entire anode terminal region 31. The water-repellent layer 70 is provided continuously from the masking region 61 onto the acrylic resin layer 80. The solid electrolytic capacitor element obtained after peeling off the acrylic resin layer and the water-repellent layer has the configuration shown in FIG. 1 . The anode terminal region after peeling off the acrylic resin layer and the water-repellent layer is an area in which the valve metal substrate is exposed as a whole, providing a wide area suitable for resistance welding. This area can be used to perform resistance welding to manufacture a solid electrolytic capacitor.

[0072] The present specification discloses the following:

[0073] The present disclosure (1) provides a method for manufacturing a solid electrolytic capacitor including a solid electrolytic capacitor element having a valve metal substrate having an anode terminal region and a cathode formation region, a dielectric layer formed on the valve metal substrate, a solid electrolyte layer formed on the dielectric layer, and a current collecting layer formed on the solid electrolyte layer, the method comprising the steps of: forming a masking region on the valve metal substrate to separate the anode terminal region and the cathode formation region and to insulate the valve metal substrate from a counter electrode; providing a water-repellent layer on at least a part of the anode-side masking region located closer to the anode terminal region than the cathode-side masking region, while not providing a water-repellent layer in a cathode-side masking region that is a predetermined region on the surface of the masking region and including an end portion on the cathode formation region side; and applying a raw material liquid containing a material for forming the solid electrolyte layer from the cathode formation region to the cathode-side masking region of the masking region to form the solid electrolyte layer.

[0074] The present disclosure (2) is a method for manufacturing a solid electrolytic capacitor according to the present disclosure (1), which includes, after applying the raw material liquid, performing a step of peeling off the water-repellent layer provided on the surface of the masking region.

[0075] The present disclosure (3) is a method for manufacturing a solid electrolytic capacitor according to the present disclosure (1) or (2), in which the water-repellent layer is provided in a part of the anode-side masking region, and a region of the anode-side masking region that is located further toward the anode terminal region than the region where the water-repellent layer is provided is defined as a region of the anode-side masking region where the water-repellent layer is not provided.

[0076] The present disclosure (4) is the method for manufacturing a solid electrolytic capacitor according to the present disclosure (1) or (2), further comprising providing the water-repellent layer on the valve metal substrate in the anode terminal region.

[0077] The present disclosure (5) is the method for manufacturing a solid electrolytic capacitor according to the present disclosure (4), further comprising the step of peeling off the water-repellent layer provided in the anode terminal region after applying the raw material solution.

[0078] The present disclosure (6) is the method for manufacturing a solid electrolytic capacitor according to the present disclosure (1) or (2), further comprising providing an acrylic resin layer on the valve metal substrate in the anode terminal region, and providing the water-repellent layer on the acrylic resin layer.

[0079] The present disclosure (7) is the method for manufacturing a solid electrolytic capacitor according to the present disclosure (6), in which the acrylic resin layer is provided over the entire anode terminal region.

[0080] The present disclosure (8) is a method for manufacturing a solid electrolytic capacitor according to the present disclosure (6) or (7), further comprising the step of peeling off the acrylic resin layer and the water-repellent layer provided on the acrylic resin layer after applying the raw material liquid.

[0081] The present disclosure (9) is a method for manufacturing a solid electrolytic capacitor according to the present disclosure (8), which includes a step of welding a plurality of the solid electrolytic capacitor elements by resistance welding the surface of the valve metal base exposed by peeling off the acrylic resin layer.

[0082] DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 1d Solid electrolytic capacitor element 10 Valve action metal substrate 20 Dielectric layer 31 Anode terminal region 32 Cathode formation region 33 Anode end 34 Cathode end 40 Solid electrolyte layer 50 Current collecting layer 51 Carbon layer 52 Metal layer 60 Masking member 61 Masking region 62 End of the surface of the masking region on the cathode formation region side 63 Cathode side masking region 64 End of the surface of the masking region on the anode terminal region side 65 Anode side masking region 65a Region of the anode side masking region where a water-repellent layer is provided 65b Region of the anode side masking region where a water-repellent layer is not provided 70 Water-repellent layer 80 Acrylic resin layer 300 Solid electrolytic capacitor 310 Exterior body 310a First main surface 310b Second main surface 310c First side surface 310d: Second side surface; 310e: First end surface; 310f: Second end surface; 319: Conductive member; 320: First external electrode; 330: Second external electrode; 340: Capacitor element assembly

Claims

1. A method for manufacturing a solid electrolytic capacitor comprising a solid electrolytic capacitor element having a valve metal base having an anode terminal region and a cathode formation region, a dielectric layer formed on the valve metal base, a solid electrolyte layer formed on the dielectric layer, and a current collecting layer formed on the solid electrolyte layer, the method comprising the steps of: forming a masking region made of a masking material on the valve metal base to separate the anode terminal region from the cathode formation region and to insulate the valve metal base from a counter electrode; providing a water-repellent layer on at least a part of the anode-side masking region located closer to the anode terminal region than the cathode-side masking region, while not providing a water-repellent layer in a cathode-side masking region which is a predetermined region on the surface of the masking region and which includes an end portion on the cathode formation region side; and applying a raw material liquid containing a material for forming the solid electrolyte layer from the cathode formation region to the cathode-side masking region of the masking region to form the solid electrolyte layer.

2. The method for producing a solid electrolytic capacitor according to claim 1, further comprising the step of peeling off the water-repellent layer provided on the surface of the masking region after applying the raw material liquid.

3. A method for manufacturing a solid electrolytic capacitor as described in claim 1 or 2, wherein the water-repellent layer is provided on a portion of the anode side masking region, and a region of the anode side masking region that is located further toward the anode terminal region than the region where the water-repellent layer is provided is defined as a region of the anode side masking region where the water-repellent layer is not provided.

4. The method for producing a solid electrolytic capacitor according to claim 1 or 2, further comprising providing a water-repellent layer on the valve metal substrate in the anode terminal region.

5. The method for producing a solid electrolytic capacitor according to claim 4, further comprising the step of peeling off the water-repellent layer provided on the anode terminal area after applying the starting material solution.

6. The method for producing a solid electrolytic capacitor according to claim 1 or 2, further comprising providing an acrylic resin layer on the valve metal substrate in the anode terminal region, and providing the water-repellent layer on the acrylic resin layer.

7. The method for producing a solid electrolytic capacitor according to claim 6, wherein the acrylic resin layer is provided over the entire anode terminal area.

8. The method for producing a solid electrolytic capacitor according to claim 6 or 7, further comprising the step of peeling off the acrylic resin layer and the water-repellent layer provided on the acrylic resin layer after applying the raw material liquid.

9. The method for producing a solid electrolytic capacitor according to claim 8, further comprising the step of resistance welding the surface of the valve metal base exposed by peeling off the acrylic resin layer, thereby welding a plurality of the solid electrolytic capacitor elements together.

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