Solid electrolytic capacitor and its manufacturing method

Abstract

To provide a solid electrolytic capacitor having high reliability and high productivity by maintaining high airtightness while maintaining excellent electrical characteristics and a manufacturing method of the same.SOLUTION: A solid electrolytic capacitor comprises: a capacitor element 1 which has an anode body 2, a dielectric oxide covering layer 3 covering the anode body 2, and a cathode body 6 formed on the dielectric oxide covering layer 3 so as to be insulated from the anode body 2; an exterior body 10 which covers the capacitor element 1; a contact layer 11 which is formed in an anode terminal part 9 being an end of the anode body 2 and has a surface 11S with prescribed surface roughness; and an anode side electrode layer (12) which covers the surface 11S.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] As electronic devices operate at higher frequencies, capacitors, which are electronic components, are also required to have excellent impedance characteristics in the high-frequency range. To meet this demand, various solid electrolytic capacitors using conductive polymers with high electrical conductivity as the solid electrolyte have been investigated. One such solid electrolytic capacitor is disclosed in Patent Document 1, for example.

[0003] In recent years, there has been a strong demand for smaller, larger capacitance solid electrolytic capacitors used in the CPU periphery of personal computers. Furthermore, there is also a demand for lower ESR (equivalent series resistance) to accommodate higher frequencies, and lower ESL (equivalent series inductance) for superior noise reduction and transient response. Various studies are being conducted to meet these demands.

[0004] The configuration of the conventional stacked solid electrolytic capacitor described in Patent Document 1 will be described with reference to Figure 6. A solid capacitor element 31 is constructed by stacking multiple capacitor elements. The capacitor element includes a valve metal substrate 34 having a core portion 35 and a rough surface portion 36 formed along its surface, a dielectric oxide film layer 37 formed on the rough surface portion 36, and a composite layer 39 of a solid electrolyte layer and a current collector layer formed on the dielectric oxide film layer 37. The current collector layers of the multiple capacitor elements are electrically connected to each other.

[0005] An electrically insulating exterior 43 covers the laminate 33, leaving one end surface of the valve metal substrate 34 exposed. An anode-side external electrode 47 electrically connected to the core 35 of the valve metal substrate 34 is provided on one end surface of the exterior 43. A cathode-side external electrode 48 electrically connected to the current collecting layer is provided on the other end surface of the exterior 43.

[0006] The anode-side external electrode 47 is composed of a first conductive layer 49, a second conductive layer 50, and a third conductive layer 51. The first conductive layer 49 is formed so as to be in direct contact with the core 35 of the valve metal base 34, and the second conductive layer 50 is formed on the outside of the first conductive layer 49. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2014 / 188833 Summary of the Invention [Problem to be solved by the invention]

[0008] In the solid electrolytic capacitor disclosed in Patent Document 1, a first conductive layer 49 is formed by sputtering or the like on one end surface of a valve metal substrate 34, and then a second conductive layer 50 and a third conductive layer 51 are sequentially formed to cover the first conductive layer 49. In such a case, it is considered that the conductive layers are bonded to each other by the anchor effect.

[0009] The bonding strength between conductive layers due to the anchor effect is relatively low, making it prone to defects such as peeling. Defects such as peeling can reduce the electrical and mechanical properties (mechanical strength) of solid electrolytic capacitors, so measures to prevent this are needed.

[0010] An object of the present disclosure is to provide a solid electrolytic capacitor with improved electrical and mechanical properties and a method for manufacturing the same. [Means for solving the problem]

[0011] In order to achieve the above object, a solid electrolytic capacitor according to one aspect of the present disclosure includes: a capacitor element having an anode body, a dielectric oxide coating layer covering the anode body, and a cathode body formed on the dielectric oxide coating layer; an exterior body covering the capacitor element; a contact layer formed on an anode terminal portion that is an end of the anode body and having a surface with a predetermined surface roughness; and an anode-side electrode layer covering the surface.

[0012] A method for manufacturing a solid electrolytic capacitor according to one aspect of the present disclosure includes the steps of forming a capacitor element having an anode body, covering the capacitor element with an exterior body, exposing an anode terminal portion, which is an end portion of the anode body, from the exterior body, forming a contact layer on the anode terminal portion, forming a predetermined roughness on the surface of the contact layer, and covering the surface of the contact layer with an anode-side electrode layer. [Effects of the Invention]

[0013] It is possible to provide a solid electrolytic capacitor with improved electrical and mechanical properties, and a method for manufacturing the same. [Brief explanation of the drawings]

[0014] [Figure 1A] FIG. 1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present disclosure; [Figure 1B] Top view of solid electrolytic capacitor [Figure 1C] A cross-sectional view taken along line A-A' in FIG. 1B. [Figure 2] FIG. 1 is an enlarged cross-sectional view showing a preferred cross-sectional shape of a contact layer according to the present disclosure. [Figure 3] Enlarged cross-sectional view of a contact layer formed by a method other than cold spray [Figure 4A] 1 is a cross-sectional view of a solid electrolytic capacitor during a lamination step in a manufacturing method of the solid electrolytic capacitor; [Figure 4B] 1 is a cross-sectional view of a solid electrolytic capacitor during a sealing step in a manufacturing method of the solid electrolytic capacitor; [Figure 4C] 1 is a cross-sectional view of a solid electrolytic capacitor in an end surface forming step of a manufacturing method of the solid electrolytic capacitor; [Figure 5A] 1 is a cross-sectional view of a solid electrolytic capacitor in a contact layer formation step of a manufacturing method of the solid electrolytic capacitor; [Figure 5B] 1 is a cross-sectional view of a solid electrolytic capacitor in an electrode layer forming step of a manufacturing method of the solid electrolytic capacitor; [Figure 5C] 1 is a cross-sectional view of a solid electrolytic capacitor in an external electrode formation step of a manufacturing method of the solid electrolytic capacitor; [Figure 6] FIG. 1 is a diagram for explaining the configuration of a conventional multilayer solid electrolytic capacitor described in Patent Document 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] <Structure> Fig. 1A is a perspective view of a solid electrolytic capacitor according to an embodiment of the present disclosure. Fig. 1B is a top view of the solid electrolytic capacitor. Fig. 1C is a cross-sectional view taken along line A-A' in Fig. 1B. Note that the upward direction in the following description corresponds to the upward direction in Fig. 1C, and the downward direction in the following description corresponds to the downward direction in Fig. 1C.

[0017] The solid electrolytic capacitor 20 shown in FIGS. 1A to 1C includes a capacitor element 1, a support member 7, a conductive material 8, an anode terminal portion 9, an outer casing 10, a contact layer 11, an anode-side electrode layer 12a, a cathode-side electrode layer 12b, an anode-side external electrode 13a, and a cathode-side external electrode 13b.

[0018] (Capacitor element 1) As shown in FIG. 1C, capacitor element 1 includes anode body 2, dielectric oxide film layer 3, insulating layer 4, solid electrolyte layer 5, and cathode body 6.

[0019] The dielectric oxide layer 3 is obtained by forming a porous layer on both sides of an aluminum (Al) foil, which is a valve metal, by a method such as chemical etching, and then forming a dielectric layer on the porous layer. The anode body 2 is the core portion of the Al foil that remains unporous. The dielectric oxide layer 3 is disposed on the upper and lower surfaces of the anode body 2.

[0020] The thickness of anode body 2 and the thickness of dielectric oxide layer 3 are each 20 μm or more and 80 μm or less. The material of anode body 2 and dielectric oxide layer 3 is not limited to Al foil and may be, for example, Ta (tantalum), which is a commonly used capacitor material.

[0021] The solid electrolyte layer 5 is the anode-side end of the anode body 2. An insulating layer 4 is formed on the upper and lower surfaces of the anode body 2 near the solid electrolyte layer 5. The insulating layer 4 electrically separates the solid electrolyte layer 5 from the dielectric oxide film layer 3 and the cathode body 6, which will be described later.

[0022] The insulating layer 4 may be formed by any suitable known method. For example, a method may be used in which a portion of the dielectric oxide layer 3 is completely removed by laser or chemical etching, and then the anode body 2 is coated with an insulating resin such as polyimide, polyamide, or epoxy. Alternatively, a method may be used in which a compressive stress is applied to the dielectric oxide layer 3 to make it a dense layer and thereby provide insulation, or a method may be used in which a portion of the porous dielectric oxide layer 3 is impregnated with an insulating resin.

[0023] 1 illustrates an example in which the insulating layer 4 has a single structure, the insulating layer 4 may have a composite structure in which different materials are combined. For example, the insulating layer 4 may have a laminated structure of a dense Al oxide film and a polyimide resin.

[0024] Dielectric oxide film layer 3, which is insulated from solid electrolyte layer 5 by insulating layer 4, is configured such that a solid electrolyte layer is formed on a porous layer formed by chemical etching or the like on both sides of an Al foil. The solid electrolyte layer is formed by chemical polymerization, electrolytic polymerization, or the like using a conductive polymer material such as polypyrrole or polythiophene.

[0025] A cathode body 6 is formed on the dielectric oxide film layer 3. The cathode body 6 is formed by sequentially laminating a carbon layer and a conductive Ag (silver) paste layer by, for example, a printing method or a transfer method.

[0026] The cathode body 6 is not limited to a laminated structure of a carbon layer and a conductive Ag paste layer. For example, the cathode body 6 may contain a conductive paste using a filler other than Ag, a sintering material, or the like, instead of the conductive Ag paste. Examples of fillers other than Ag include Cu (copper) and Ni (nickel) core materials coated with Ag.

[0027] (Capacitor element 1) 1C, solid electrolytic capacitor 20 has multiple capacitor elements 1 stacked on top of each other in the vertical direction. In the example shown in Fig. 1C, three capacitor elements 1a, 1b, and 1c are stacked, but in the present disclosure, the number of capacitor elements 1 stacked on top of each other is not limited to three.

[0028] Capacitor element 1c, which is arranged at the bottom, is fixed onto support member 7 via conductive material 8. Capacitor elements 1b and 1a are stacked on top of fixed capacitor element 1c via conductive material 8. In the following description, any one of stacked capacitor elements 1a, 1b, and 1c or a plurality of capacitor elements may be referred to as capacitor element 1.

[0029] The support member 7 may be, for example, a substrate with excellent heat resistance, such as a glass epoxy substrate, a BT (Bismaleimide-Triazine) resin or polyimide resin substrate, or a Cu lead frame. However, when using a conductive material such as a lead frame, it is necessary to insulate the anode side from the cathode side.

[0030] For example, a conductive paste such as a conductive Ag paste is used as the conductive material 8. The conductive material 8 is electrically connected to the cathode body 6 of the capacitor element 1. Note that the conductive material 8 may be in the form of an adhesive sheet instead of a paste.

[0031] In the example shown in FIG. 1C, only conductive material 8 is provided between adjacent capacitor elements, but in addition to conductive material 8, for example, a metal foil such as Al, Cu, or In (indium) may be interposed.

[0032] The capacitor elements 1 are covered with an exterior body 10 so that a cathode terminal 8b, which is the end on the cathode side, and an anode terminal 9, which is the end on the anode side, are exposed.

[0033] (contact layer 11) An anode terminal 9 is formed at the anode side end of the anode body 2, and as described above, the anode terminal 9 is not covered with the exterior body .

[0034] The anode terminal 9 is provided with a contact layer 11 made of a metal material that has a lower ionization tendency than the anode body 2. The contact layer 11 is not formed on the exterior body 10 or the insulating layer 4, which are made of a resin-based material, but is selectively formed only on the surface of the anode terminal 9, which is made of a metal material. An anode-side electrode layer 12a and an anode-side external electrode 13a are formed further outside the contact layer 11. The contact layer 11 is electrically connected to the anode-side electrode layer 12a and the anode-side external electrode 13a. As a result, electrical conduction between the anode terminals 9 of the stacked capacitor elements 1 is achieved mainly via the anode-side electrode layer 12a.

[0035] As described above, when the anode body 2 is made of Al, examples of the material for the contact layer 11 include Zn (zinc), Ni, Sn, Cu, and Ag. By using a metal material with a lower ionization tendency than the anode body 2, the formation of an oxide film on the surface of the contact layer 11 is suppressed, thereby ensuring a more reliable electrical connection between the contact layer 11 and the anode-side electrode layer 12a.

[0036] It is more preferable to use Cu, Zn, or Ag, which have close interatomic distances, as the material for contact layer 11. When Cu, Zn, or Ag is used as the material for contact layer 11, an alloy layer is formed between contact layer 11 and anode body 2 due to metallic bonding, thereby further strengthening the bonding strength between contact layer 11 and anode body 2. In addition to being made of a single-element metal, contact layer 11 may also be made of an alloy such as bronze or brass, or may be made by stacking different metals such as Cu and Ag.

[0037] 2 is an enlarged cross-sectional view showing a preferred cross-sectional shape of the contact layer 11 according to the present disclosure. The surface 11S of the contact layer 11 facing the anode side electrode layer 12 has a predetermined roughness. The surface roughness (arithmetic mean roughness Ra) of the surface 11S of the contact layer 11 is preferably, for example, 3 μm or more. Such surface roughness increases the surface area of ​​the surface 11S, thereby increasing the contact area between the contact layer 11 and the anode side electrode layer 12a. This reduces the electrical resistance between the contact layer 11 and the anode side electrode layer 12a and increases the bonding strength (mechanical strength), as will be described in detail later.

[0038] The manufacturing process of the contact layer 11 will be described in detail later, but the contact layer 11 is preferably formed by cold spraying. The cold spraying is a technique in which metal particles on the order of several μm to several tens of μm are accelerated to subsonic, sonic, or supersonic speeds using compressed gas such as air, nitrogen, or helium, and collide with a substrate in a solid state to bond the metal particles to the substrate, thereby forming a metal coating.

[0039] When the contact layer 11 is formed by the cold spray method, the grain shapes of the metal particles that were collided to form the contact layer 11 remain on the surface 11S. Therefore, as shown in Fig. 2, the surface 11S of the contact layer 11 has the above-mentioned surface roughness due to the unevenness caused by the grain shapes of the metal particles. For the reason described below, by using metal particles with a median diameter of 5 µm to 10 µm, for example, the surface roughness of the surface 11S can be made 3 µm or more.

[0040] In the present disclosure, the contact layer 11 does not necessarily have to be formed by the cold spray method, but may be formed by, for example, a plating method, a solder dip method, a sputtering method, or a vapor deposition method. In this case, after forming the contact layer 11 by the plating method, the solder dip method, the sputtering method, or the vapor deposition method, a step of physically roughening the surface 11S by a blasting method or the like is required. Figure 3 is an enlarged cross-sectional view of the contact layer 11 formed by a method other than the cold spray method.

[0041] <Anode side electrode layer 12a and cathode side electrode layer 12b> As described above, the laminate of capacitor element 1 is covered with exterior housing 10, but cathode terminal 8b, which is the end on the cathode side, and anode terminal 9, which is the end on the anode side, are exposed from exterior housing 10. In the following description, an end face of the laminate of capacitor element 1 that includes anode terminal 9, anode side end face 4a of insulating layer 4, anode side end face 10a of exterior housing 10, and anode side end face 7a of support member 7 will be referred to as anode side end face 14. In addition, an end face of the laminate of capacitor element 1 that includes cathode terminal 8b, which is the cathode side end face of conductive material 8, cathode side end face 10b of exterior housing 10, and cathode side end face 7b of support member 7 will be referred to as cathode side end face 15.

[0042] The anode side end surface 14 and the cathode side end surface 15 are covered with an anode side electrode layer 12a and a cathode side electrode layer 12b, respectively. The anode side electrode layer 12a and the cathode side electrode layer 12b are covered with an anode side external electrode 13a and a cathode side external electrode 13b, respectively.

[0043] The material for the anode side electrode layer 12a and the cathode side electrode layer 12b is preferably a conductive paste material (conductive resin material) in which a metal filler (metal particles) such as Ag or Cu is mixed into a resin material that serves as a binder. This allows a binder component suitable for bonding to the materials that constitute the insulating layer 4, the exterior body 10, and the support member 7 to be added to the resin material, which is expected to bond the insulating layer 4, the exterior body 10, and the support member 7 to the anode side electrode layer 12a and the cathode side electrode layer 12b by chemical bonding or hydrogen bonding.

[0044] Furthermore, it is desirable to set the surface roughness (Ra) of each of the anode-side end face 4a and cathode-side end face 4b of the insulating layer 4, the anode-side end face 10a and cathode-side end face 10b of the exterior body 10, and the anode-side end face 7a and cathode-side end face 7b of the support member 7 to 5 μm or more. This configuration increases the contact area between each end face and the anode-side electrode layer 12a and cathode-side electrode layer 12b, and also provides a strong bond due to the anchor effect.

[0045] <Manufacturing method> Next, a method for manufacturing a solid electrolytic capacitor according to an embodiment of the present disclosure will be described with reference to Figures 4A to 4C and Figures 5A to 5C. Figures 4A to 4C and Figures 5A to 5C are cross-sectional views of a solid electrolytic capacitor in each step of the method for manufacturing a solid electrolytic capacitor.

[0046] (Lamination process) First, the lamination step shown in Fig. 4A is performed. In the lamination step, an appropriate amount of conductive material 8 is applied onto support member 7, and one of a plurality of capacitor elements 1 prepared in advance (capacitor element 1c) is placed thereon with precision.

[0047] Next, an appropriate amount of conductive material 8 is applied onto capacitor element 1c, and capacitor element 1b is placed on top of that. Furthermore, an appropriate amount of conductive material 8 is applied onto capacitor element 1b, and capacitor element 1a is placed on top of that.

[0048] The conductive material 8 can be applied by any known method, such as a dispensing method, printing, an inkjet method, a dipping method, or a transfer method.

[0049] Then, the conductive material 8 is thermally cured using a high-temperature furnace or the like to establish electrical continuity between the cathode bodies 6 of each capacitor element 1. Note that the means for thermal curing is not limited to a high-temperature furnace, and for example, a hot plate, a reflow furnace, or the like may also be used.

[0050] In the above description, the capacitor elements 1 are stacked sequentially at one location on the support member 7, but multiple capacitor elements may be stacked simultaneously at multiple locations on the support member 7 (for example, in a matrix of multiple columns and rows).

[0051] (Sealing process) Next, the sealing step shown in Fig. 4B is performed. In the sealing step, as shown in Fig. 4B, the stacked capacitor elements 1 are sealed with an exterior body 10 so as to cover the entirety of the stacked capacitor elements 1. At this time, it is preferable that the exterior body 10 also fills the gaps between the stacked capacitor elements 1 and the gaps between the support member 7 and the capacitor elements 1. The gaps between the stacked capacitor elements 1 and the gaps between the support member 7 and the capacitor elements 1 may be filled in advance with a resin material other than the exterior body 10.

[0052] The method for sealing the capacitor element 1 with the exterior body 10 may be any known method, such as a transfer method, a compression method, or a method in which a liquid resin is poured into a mold and then thermally cured.

[0053] (End surface processing) Next, an end surface exposing step shown in Fig. 4C is performed. In this end surface exposing step, the anode side of capacitor element 1 sealed in package 10 is exposing anode terminal 9 from package 10, thereby forming anode-side end surface 14. On the cathode side, the end surface is exposing cathode terminal 8b, thereby forming cathode-side end surface 15.

[0054] The edge exposure method may be, for example, a method in which a dicing blade with diamond particles fixed with a bonding material is rotated at high speed to cut capacitor element 1 sealed in package 10.

[0055] (Contact layer formation process) Next, the contact layer formation step shown in Fig. 5A is performed. In the contact layer formation step, first, each end face (anode-side end face 4a, anode-side end face 10a, and anode-side end face 7a) constituting the anode-side end face 14 is roughened. This strengthens the adhesion between the anode-side end face 4a, anode-side end face 10a, and anode-side end face 7a and the anode-side electrode layer 12a (described later) due to an anchor effect. Then, a contact layer 11 is selectively formed only on the surface of the anode terminal portion 9.

[0056] As described above, the cold spray method is preferably used as the method for forming contact layer 11. When Cu particles, which are the material for contact layer 11, are sprayed onto anode-side end face 14 by cold spraying, the Cu particles do not bond to anode-side end face 4a, anode-side end face 10a, and anode-side end face 7a, which are made of a resin material, but bond only to anode terminal 9, which is made of a metal material.

[0057] More specifically, the Cu particles that collide with the anode terminal 9 at high speed break through the oxide film on the surface of the anode terminal 9. As a result, the Al and Cu particles, which are the materials of the anode terminal 9, are plastically deformed at the collision point by the energy of the collision, and a new surface is formed. When the new surfaces of the Al and Cu particles come into contact with each other, an alloy layer is formed by metallic bonding between the Al and Cu.

[0058] At the anode-side end surface 14, the thickness of the anode terminal 9 made of Al is thinner than the anode-side end surface 4a, anode-side end surface 10a, and anode-side end surface 7a, which are made of resin. Therefore, Cu particles are less likely to adhere to the upper and lower ends of the end surface of the anode terminal 9, which correspond to the boundary with the resin. Therefore, the cross-sectional shape of the surface 11S in the thickness direction of the anode body 2 has a convex shape at the center, as shown in FIG. 2 . Furthermore, because the Cu particles adhere to the surface 11S after plastic deformation while retaining their solid-phase particle shape, irregularities due to the particle shape are formed. This provides the surface 11S with a surface roughness determined by the size of the Cu particles. As described above, the surface roughness (Ra) of the surface 11S is preferably 3 μm or more. Therefore, the size of the Cu particles used as the material for the contact layer 11 is preferably approximately 5 μm to 10 μm in median diameter. Furthermore, the Cu particles are preferably spherical or nearly spherical.

[0059] By using Cu particles with a large median diameter of approximately 5 μm to 10 μm, sufficient acceleration can be achieved when forming contact layer 11 by cold spraying, making it easier to form a good metallic bond with anode terminal portion 9.

[0060] Furthermore, by using spherical or nearly spherical Cu particles, sufficient acceleration can be achieved, making it easier to form a good metallic bond with the anode terminal 9. When the Cu particles are spherical or have a shape other than spherical, such as a rod or polyhedron, the volume of the particles creates acute corners on the surface 11S. This makes it easier for cracks to form at the acute corners in the anode-side electrode layer 12a at the interface between the contact layer 11 and the anode-side electrode layer 12a formed in the electrode layer formation step described below. In other words, by using spherical or spherical Cu particles, the surface 11S is mainly formed as a curved surface, making it less likely for cracks to form.

[0061] Setting the surface roughness of the surface 11S of the contact layer 11 to 3 μm or more provides the following advantages. The anode-side electrode layer 12a is formed on the surface 11S side of the contact layer 11 in the electrode layer formation step described below. Here, the conductive filler particles, such as Ag, contained in the anode-side electrode layer 12a have a size of less than 1 μm. Therefore, setting the surface roughness of the surface 11S to 3 μm or more makes it easier for the conductive filler particles to penetrate into the irregularities of the surface 11S. This increases the contact area between the surface 11S and the anode-side electrode layer 12a and reduces the contact resistance compared to when the surface 11S is formed smoothly. Furthermore, the anchor effect created by the penetration of part of the anode-side electrode layer 12a into the irregularities of the surface 11S increases the bonding strength (mechanical strength) between the contact layer 11 and the anode-side electrode layer 12a.

[0062] In the present disclosure, it is preferable to use a cold spray method to form contact layer 11. However, as described above, contact layer 11 may also be formed by other metal film formation methods, such as plating, solder dipping, sputtering, or vapor deposition. When using plating, Ni, which has a low ionization tendency, may be plated on the Al surface of anode terminal portion 9. Alternatively, contact layer 11 may be formed by combining multiple layers, such as Ni+Ag plating. In such a case, the cross-sectional shape of surface 11S in the thickness direction of anode body 2 is substantially linear, as shown in FIG. 3 .

[0063] When using a metal film formation method other than cold spraying, such as plating, solder dipping, sputtering, or vapor deposition, a physical surface roughening step is required after forming the metal film, as described above. A roughening method such as blasting, in which non-metallic particles such as alumina, sand, or glass are sprayed onto the surface, can be used. Even with this method, a contact layer 11 having the surface roughness shown in FIG. 3 can be formed. Note that by using fine non-metallic powder of 3 μm or more during the blasting process, the surface roughness of the surface 11S can be made 3 μm or more.

[0064] Although not shown, it is also possible to prevent the intrusion of plating solution and the like by filling insulating layer 4 with insulating resin or the like to improve sealing properties.

[0065] (Electrode layer formation process) 5B, an electrode layer forming step is performed. In the electrode layer forming step, an anode-side electrode layer 12a and a cathode-side electrode layer 12b are formed on the anode-side end surface 14 and the cathode-side end surface 15, respectively. As a result, the anode body 2 is electrically connected to the anode-side electrode layer 12a, and the cathode body 6 is electrically connected to the cathode-side electrode layer 12b.

[0066] Specifically, the anode-side electrode layer 12a and the cathode-side electrode layer 12b are formed by applying Ag paste to the anode-side end surface 14 and the cathode-side end surface 15 by a dipping method, a transfer method, a printing method, a dispensing method, or the like, and then curing the paste at a high temperature.

[0067] The anode-side electrode layer 12a may cover not only the anode-side end face 14 but also at least a part of the upper surface of the exterior body 10 or the lower surface of the support member 7. Similarly, the cathode-side electrode layer 12b may cover not only the cathode-side end face 15 but also a part of the upper surface of the exterior body 10 or the lower surface of the support member 7.

[0068] (External electrode formation process) Finally, an external electrode forming step is performed as shown in Fig. 5C. As shown in Fig. 5C, an anode-side external electrode 13a is formed on the outer surface of the anode-side electrode layer 12a, and a cathode-side external electrode 13b is formed on the outer surface of the cathode-side electrode layer 12b.

[0069] Specifically, the anode side external electrode 13a and the cathode side external electrode 13b are formed by barrel plating, which is one of the electrolytic plating methods, etc. The anode side external electrode 13a and the cathode side external electrode 13b have a laminated structure of, for example, Ni and Sn.

[0070] The anode side external electrode 13a and the cathode side external electrode 13b may be formed as a structure containing Ag and Sn using the above-mentioned cold spray method, or may be formed by a combination of barrel plating and solder dipping.

[0071] Furthermore, the anode-side external electrode 13a and the cathode-side external electrode 13b may be formed by a method in which a cap made of a Cu material that has been previously coated with an Sn film is adhered to the anode-side electrode layer 12a and the cathode-side electrode layer 12b that are formed of an Ag paste that functions as an adhesive.

[0072] <Effects> A solid electrolytic capacitor 20 according to an embodiment of the present disclosure includes a capacitor element 1 having an anode body 2, a dielectric oxide coating layer 3 covering the anode body 2, and a cathode body 6 formed on the dielectric oxide coating layer 3, an exterior body 10 covering the capacitor element 1, a contact layer 11 formed on an anode terminal portion 9 which is an end portion of the anode body 2 and having a surface 11S with a predetermined surface roughness, and an anode-side electrode layer 12 covering the surface 11S.

[0073] The contact layer 11 is metallurgically bonded to the anode terminal 9 made of a valve metal foil and has a predetermined surface roughness, thereby increasing the contact area between the contact layer 11 and the anode-side electrode layer 12a. This reduces the contact resistance between the contact layer 11 and the anode-side electrode layer 12a and increases the bonding strength between the contact layer 11 and the anode-side electrode layer 12a. This ensures a low-resistance current path from the anode body 2 to the anode-side external electrode 13a, improving the electrical characteristics of the solid electrolytic capacitor 20 and its mechanical strength, thereby increasing reliability.

[0074] The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure. [Industrial Applicability]

[0075] The solid electrolytic capacitor of the present invention has high reliability and productivity while maintaining good electrical properties, and can be used as a capacitor in a wide range of fields, including personal computers, mobile terminals, industrial applications, and automotive applications. [Explanation of symbols]

[0076] 20 Solid electrolytic capacitors 1, 1a, 1b, 1c capacitor elements 2 anode body 3. Dielectric oxide layer 4. Insulation layer 4a Anode side end face 4b Cathode side end face 5 Solid electrolyte layer 6 cathode body 7 Support member 7a Anode side end face 7b Cathode side end face 8 Conductive materials 8b Cathode terminal 9 Anode terminal section 10. Exterior body 10a Anode side end face 10b Cathode side end face 11 Contact layer 11S surface 12a Anode side electrode layer 12b Cathode side electrode layer 13a Anode side external electrode 13b Cathode side external electrode 14 Anode side end face 15 Cathode side end face

Claims

1. a capacitor element having an anode body, a dielectric oxide film layer covering the anode body, and a cathode body formed on the dielectric oxide film layer; an exterior body that covers the capacitor element; a contact layer formed on an anode terminal portion, which is an end portion of the anode body, and having a surface with a predetermined surface roughness; an anode-side electrode layer covering the surface; Equipped with the anode layer contains a conductive paste material in which a metal filler is mixed in a resin, The size of the metal filler is smaller than the surface roughness of the surface of the contact layer. Solid electrolytic capacitor.

2. The surface roughness of the surface of the contact layer is 3 μm or more. The solid electrolytic capacitor according to claim 1 .

3. The cross-sectional shape of the surface in the thickness direction of the anode body is formed so that the central portion is convex or substantially linear. The solid electrolytic capacitor according to claim 1 or 2.

4. the contact layer is a metal coating formed by depositing metal particles on the anode terminal portion; The solid electrolytic capacitor according to claim 1 .

5. The metal particles are spherical or approximately spherical. The solid electrolytic capacitor according to claim 4 .

6. The contact layer and the anode terminal are metallurgically bonded. The solid electrolytic capacitor according to claim 4 or 5.

7. the contact layer is formed of a metal having a lower ionization tendency than the anode body; The solid electrolytic capacitor according to claim 1 .

8. forming a capacitor element having an anode body; covering the capacitor element with an exterior body; exposing an anode terminal portion, which is an end portion of the anode body, from the exterior packaging; forming a contact layer on the anode terminal; forming a predetermined roughness on the surface of the contact layer; a step of covering a surface of the contact layer with an anode-side electrode layer; Including, the anode layer contains a conductive paste material in which a metal filler is mixed in a resin, The size of the metal filler is smaller than the surface roughness of the surface of the contact layer. A method for manufacturing a solid electrolytic capacitor.

9. The step of forming the contact layer and the step of forming the predetermined roughness on the surface of the contact layer are performed simultaneously. The method for manufacturing the solid electrolytic capacitor according to claim 8 .

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