Solid electrolytic capacitor and method for manufacturing the same

Abstract

The present application provides a solid electrolytic capacitor and a manufacturing method thereof. The solid electrolytic capacitor is provided with: a capacitor element (1) having an anode body (2), a dielectric oxide film layer (3) covering the anode body (2), and a cathode body (6) formed on the dielectric oxide film layer (3) so as to be insulated from the anode body (2); an outer body (10) covering the capacitor element (1); a contact layer (11) formed on an end portion of the anode body (2), i.e., an anode terminal portion (9), having a surface (11S) with a prescribed surface roughness; and an anode-side electrode layer (12) covering the surface (11S).

Description

TECHNICAL FIELD

[0001] The present application relates to a solid electrolytic capacitor and a manufacturing method thereof. BACKGROUND

[0002] With the high frequency of electronic devices, excellent impedance characteristics in the high frequency region are also required for capacitors, which are one of electronic components. In order to cope with such a requirement, various solid electrolytic capacitors using a conductive polymer having a high degree of electrical conduction for a solid electrolyte have been investigated. As such a solid electrolytic capacitor, for example, there is a capacitor disclosed in Patent Literature 1.

[0003] Further, in recent years, a solid electrolytic capacitor used around a CPU of a personal computer is strongly desired to be downsized and have a large capacity. Further, in response to the high frequency, a low ESR (Equivalent Series Resistance), noise removal, and a low ESL (Equivalent Series Inductance) excellent in transient response are also strongly desired. In order to cope with such strong desires, various investigations have been made.

[0004] REFERENCE Figure 6 The structure of the existing laminated solid electrolytic capacitor described in Patent Literature 1 will be described. The solid capacitor element 31 is configured by laminating a plurality of capacitor elements. The capacitor element has a valve action metal base 34 having a core portion 35 and a roughened portion 36 formed along the surface thereof, a dielectric oxide film layer 37 formed on the roughened 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 plurality of capacitor elements are electrically connected to each other.

[0005] An electrically insulating exterior 43 covers the laminate 33 in a state in which one end surface of the valve action metal base 34 is exposed. On one end surface of the exterior 43, an anode-side external electrode 47 electrically connected to the core portion 35 of the valve action metal base 34 is provided. Further, on the other end surface of the exterior 43, a cathode-side external electrode 48 electrically connected to the current collector layer is provided.

[0006] The anode-side external electrode 47 includes 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 directly contact the core portion 35 of the valve action metal base 34, and the second conductive layer 50 is formed on the outside of the first conductive layer 49.

[0007] PRIOR ART DOCUMENT

[0008] PATENT LITERATURE

[0009] Patent Literature 1: International Publication No. 2014 / 188833 SUMMARY

[0010] A solid electrolytic capacitor according to an embodiment of the present disclosure includes: 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 outer body covering the capacitor element; a contact layer formed on an end portion of the anode body, i.e., an anode terminal portion, having a surface with a prescribed surface roughness; and an anode-side electrode layer covering the surface.

[0011] A method of manufacturing a solid electrolytic capacitor according to an embodiment of the present disclosure includes: a step of forming a capacitor element having an anode body; a step of covering the capacitor element with an outer body; a step of exposing an end portion of the anode body, i.e., an anode terminal portion, from the outer body; a step of forming a contact layer on the anode terminal portion; a step of forming a prescribed roughness on a surface of the contact layer; and a step of covering the surface of the contact layer with an anode-side electrode layer. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1A is a perspective view of a solid electrolytic capacitor according to an embodiment of the present disclosure.

[0013] Figure 1B is a top view of a solid electrolytic capacitor.

[0014] Figure 1C is Figure 1B is a cross-sectional view at line A-A' of

[0015] Figure 2 is an enlarged cross-sectional view showing a preferred cross-sectional shape of a contact layer in the present disclosure.

[0016] Figure 3 is an enlarged cross-sectional view showing a case where a contact layer is formed by a method other than cold spraying.

[0017] Figure 4A is a cross-sectional view of a solid electrolytic capacitor in a lamination step of a method of manufacturing a solid electrolytic capacitor.

[0018] Figure 4B is a cross-sectional view of a solid electrolytic capacitor in a sealing step of a method of manufacturing a solid electrolytic capacitor.

[0019] Figure 4C is a cross-sectional view of a solid electrolytic capacitor in an end surface exposure step of a method of manufacturing a solid electrolytic capacitor.

[0020] Figure 5A is a cross-sectional view of a solid electrolytic capacitor in a contact layer formation step of a method of manufacturing a solid electrolytic capacitor.

[0021] Figure 5Bis a sectional view of a solid electrolytic capacitor in an electrode layer forming step of a manufacturing method of a solid electrolytic capacitor.

[0022] Figure 5C is a sectional view of a solid electrolytic capacitor in an external electrode forming step of a manufacturing method of a solid electrolytic capacitor.

[0023] Figure 6 is a diagram for explaining a structure of a conventional laminated solid electrolytic capacitor described in Patent Literature 1.

[0024] -Explanation of Symbols-

[0025] 20 solid electrolytic capacitor

[0026] 1, 1a, 1b, 1c capacitor element

[0027] 2 anode body

[0028] 3 dielectric oxide film layer

[0029] 4 insulating layer

[0030] 4a anode-side end surface

[0031] 4b cathode-side end surface

[0032] 5 solid electrolyte layer

[0033] 6 cathode body

[0034] 7 support member

[0035] 7a anode-side end surface

[0036] 7b cathode-side end surface

[0037] 8 conductive material

[0038] 8b cathode terminal portion

[0039] 9 anode terminal portion

[0040] 10 outer body

[0041] 10a anode-side end surface

[0042] 10b cathode-side end surface

[0043] 11 contact layer

[0044] 11S surface

[0045] 12a anode-side electrode layer

[0046] 12b cathode-side electrode layer

[0047] 13a anode-side external electrode

[0048] 13b cathode-side external electrode

[0049] 14 anode-side end surface

[0050] 15 cathode-side end surface DETAILED DESCRIPTION

[0051] In the solid electrolytic capacitor disclosed in Patent Document 1, after the first conductive layer 49 is formed on one end surface of the valve action metal base 34 by sputtering or the like, the second conductive layer 50 and the third conductive layer 51 are sequentially formed so as to cover the first conductive layer 49. In such a case, it is considered that the conductive layers are joined to each other by an anchoring effect.

[0052] Since the joining strength of the conductive layers to each other based on the anchoring effect is low, disqualification such as peeling is easily generated. If disqualification such as peeling is generated, the electrical characteristics and the mechanical characteristics (mechanical strength) of the solid electrolytic capacitor are reduced, and thus a countermeasure is urgently desired.

[0053] An object of the present disclosure is to provide a solid electrolytic capacitor having improved electrical characteristics and mechanical characteristics, and a manufacturing method thereof.

[0054] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0055] <Configuration>

[0056] Figure 1A is a perspective view showing a solid electrolytic capacitor according to the embodiment of the present disclosure. Figure 1B is a plan view of the solid electrolytic capacitor. Figure 1C is a cross-sectional view taken along the A-A' line of Figure 1B . In addition, the upward direction in the following description corresponds to the upward direction of Figure 1C , and the downward direction in the following description corresponds to the downward direction of Figure 1C .

[0057] Figures 1A-1C The solid electrolytic capacitor 20 shown in FIG. 1 has a capacitor element 1, a support member 7, a conductive material 8, an anode terminal portion 9, an outer body 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.

[0058] (Capacitor Element 1)

[0059] As shown in FIG. 2, the capacitor element 1 has an anode body 2, a dielectric oxide film layer 3, an insulating layer 4, a solid electrolyte layer 5, and a cathode body 6. Figure 1C

[0060] ​The dielectric oxide film layer 3 is obtained by forming a porous layer on both surfaces of an Al (aluminum) foil as a valve metal by a method such as chemical etching, and forming a dielectric film on the porous layer, for example. The anode body 2 is a core material portion of the Al foil which is not porous. The dielectric oxide film layer 3 is disposed on the upper surface and the lower surface of the anode body 2.

[0061] The thickness of the anode body 2 and the thickness of the dielectric oxide film layer 3 are each 20 μm or more and 80 μm or less. In addition, as the material of the anode body 2 and the dielectric oxide film layer 3, it is not limited to the Al foil, and can be Ta (tantalum) or the like which is generally used as a capacitor material, for example.

[0062] The anode terminal portion 9 is an end portion on the anode side of the anode body 2. In the vicinity of the anode terminal portion 9, the insulating layer 4 is formed on the upper surface and the lower surface of the anode body 2. The anode terminal portion 9 and the dielectric oxide film layer 3 and the cathode body 6 described later are electrically separated by the insulating layer 4.

[0063] As the method of forming the insulating layer 4, a known appropriate method can be employed. For example, a method in which a portion of the dielectric oxide film layer 3 is completely removed by laser or chemical etching, and then an insulating resin such as polyimide, polyamide, epoxy or the like is applied to the anode body 2 can be employed. Alternatively, for example, a method in which the dielectric oxide film layer 3 is given a compressive stress to make it a dense layer so as to have insulating properties, a method in which a portion of the porous dielectric oxide film layer 3 is impregnated with an insulating resin, or the like can be employed.

[0064] Furthermore, in Fig. 1, a case in which the insulating layer 4 is a single structure is illustrated, but the insulating layer 4 can also be a composite structure in which different materials are combined. For example, the insulating layer 4 can also be a laminated structure of a dense Al oxide film and a polyimide resin.

[0065] The dielectric oxide film layer 3 which is insulated from the solid electrolyte layer 5 by the insulating layer 4 is a structure in which the solid electrolyte layer is formed in a porous layer which is formed on both surfaces of an Al foil by a method such as chemical etching. The solid electrolyte layer is formed by a method such as chemical polymerization or electrolytic polymerization, using a conductive polymer material such as polypyrrole, polythiophene or the like, for example.

[0066] The cathode body 6 is formed on the dielectric oxide film layer 3. The cathode body 6 is a member in which a carbon layer and a conductive Ag (silver) paste layer are laminated in this order by a printing method or a transfer method or the like, for example.

[0067] Furthermore, the cathode 6 is not limited to a layered structure of carbon layer and conductive Ag paste layer. For example, the cathode 6 may replace the conductive Ag paste and include conductive paste or sintered materials using fillers other than Ag. Examples of fillers other than Ag include materials that coat Cu (copper) or Ni (nickel) core materials with Ag.

[0068] (Capacitor Element 1)

[0069] like Figure 1C As shown, the solid electrolytic capacitor 20 has multiple capacitor elements 1 stacked on top of each other in the vertical direction. Figure 1C In the example shown, three capacitor elements 1a, 1b, and 1c are stacked, but in this disclosure, the number of capacitor elements 1 that are stacked together is not limited to three.

[0070] The capacitor element 1c, located at the bottom, is fixed to the support member 7 via a conductive material 8. Capacitor elements 1b and 1a are stacked on top of the fixed capacitor element 1c via the conductive material 8. Furthermore, in the following description, any one of the stacked capacitor elements 1a, 1b, and 1c may be referred to as capacitor element 1, or multiple capacitor elements may be collectively referred to as capacitor element 1.

[0071] As the support member 7, a heat-resistant substrate such as a glass epoxy board, a BT (Bismaleimide-Triazine) resin substrate, or a polyimide resin substrate, or a lead frame made of Cu can be used. However, when using conductive materials such as lead frames, it is necessary to insulate the anode side from the cathode side.

[0072] The conductive material 8 may be, for example, a conductive paste such as conductive Ag paste. The conductive material 8 is electrically connected to the cathode 6 of the capacitor element 1. Alternatively, the conductive material 8 may not be in paste form, but rather in an adhered sheet form.

[0073] In addition, Figure 1C In the example shown, only conductive material 8 is provided between adjacent capacitor elements. For example, in addition to conductive material 8, metal foils such as Al, Cu or In (indium) may also be present.

[0074] Multiple capacitor elements 1 are covered by an outer casing 10, such that the cathode terminal portion 8b, which is the end on the cathode side, and the anode terminal portion 9, which is the end on the anode side, are exposed.

[0075] (Contact layer 11)

[0076] An anode terminal portion 9 is formed at the end of the anode body 2 on the anode side, and as described above, the anode terminal portion 9 is not covered by the outer casing 10.

[0077] In the anode terminal portion 9, a contact layer 11 using a metal material having a smaller ionization tendency than the anode body 2 is formed. The contact layer 11 is not formed on the resin-based material outer body 10 and the insulating layer 4, and is selectively formed only on the surface of the metal material anode terminal portion 9. 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. Thus, the electrical conduction between the anode terminal portions 9 of the stacked capacitor elements 1 is mainly performed via the anode-side electrode layer 12a.

[0078] In the case where the anode body 2 is formed of Al as described above, examples of the material of the contact layer 11 include Zn (zinc), Ni, Sn, Cu, Ag, and the like. By using a metal material having a smaller ionization tendency than the anode body 2, the formation of an oxide film at the surface of the contact layer 11 is suppressed, and thus the electrical connection between the contact layer 11 and the anode-side electrode layer 12a can be made more reliable.

[0079] In addition, it is more preferable to use Cu, Zn, or Ag, which have a short interatomic distance, as the material of the contact layer 11. In the case where Cu, Zn, or Ag is used as the material of the contact layer 11, an alloy layer based on metal bonding is formed between the contact layer 11 and the anode body 2, and thus the joining strength between the contact layer 11 and the anode body 2 can be made more robust. In addition, the contact layer 11 can be composed of an alloy such as bronze or brass, or can be composed of different metals such as Cu and Ag, in addition to being composed of a single element metal.

[0080] Figure 2 is an enlarged sectional view showing a preferred cross-sectional shape of the contact layer 11 in the present disclosure. The surface 11S of the contact layer 11 on the anode-side electrode layer 12 side has a prescribed 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. With such a surface roughness, the surface area of the surface 11S increases, and thus the contact area between the contact layer 11 and the anode-side electrode layer 12a also increases. Thus, as will be described in detail later, the electrical resistance between the contact layer 11 and the anode-side electrode layer 12a can be reduced, and the joining strength (mechanical strength) can be improved.

[0081] The manufacturing process of the contact layer 11 will be described in detail later, but it is preferable that the contact layer 11 be formed by a cold spraying method. The cold spraying method refers to a technique in which metal particles of several μm to several tens of μm are accelerated to subsonic speed, sonic speed, or supersonic speed by a compressed gas such as air, nitrogen, or helium, and the metal particles are made to collide with a base material while maintaining a solid phase state, and the metal particles are joined to the base material, thereby forming a metal film.

[0082] In the case where the contact layer 11 is formed by the cold spraying method, the particle shape of the metal particles colliding for the formation of the contact layer 11 remains on the surface 11S. Therefore, as shown in FIG. 10, the surface 11S of the contact layer 11 has the surface roughness described above due to the unevenness caused by the particle shape of the metal particles. The reason will be described later, but for example, by using metal particles having a median particle diameter of 5 to 10 μm, the surface roughness of the surface 11S can be set to 3 μm or more. Figure 2

[0083] In addition, in the present disclosure, the contact layer 11 can also be formed not by the cold spraying method, but for example, can be formed by an electroplating method, a dip soldering method, sputtering, or a vapor deposition method, or the like. In this case, after the contact layer 11 is formed by the electroplating method, the dip soldering method, sputtering, or the vapor deposition method, or the like, a step of physically roughening the surface 11S using a blasting method or the like is required. Figure 3

[0084] <Anode-side electrode layer 12a and cathode-side electrode layer 12b>

[0085] As described above, the stack of the capacitor element 1 is covered with the case 10, but the end portion on the cathode side, that is, the cathode terminal portion 8b, and the end portion on the anode side, that is, the anode terminal portion 9, are exposed from the case 10. In the following description, the end surface of the stack of the capacitor element 1 including the anode terminal portion 9, the anode-side end surface 4a of the insulating layer 4, the anode-side end surface 10a of the case 10, and the anode-side end surface 7a of the support member 7 is described as an anode-side end surface 14. Further, the end surface of the stack of the capacitor element 1 including the cathode-side end surface of the conductive material 8, that is, the cathode terminal portion 8b, the cathode-side end surface 10b of the case 10, and the cathode-side end surface 7b of the support member 7 is described as a cathode-side end surface 15.

[0086] The anode-side end surface 14 and the cathode-side end surface 15 are covered with the anode-side electrode layer 12a and the cathode-side electrode layer 12b, respectively. Further, the anode-side electrode layer 12a and the cathode-side electrode layer 12b are covered with the anode-side external electrode 13a and the cathode-side external electrode 13b, respectively.

[0087] The material of 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 particle) such as Ag or Cu is mixed in a resin material as a binder. Thereby, it is possible to add a binder component suitable for adhesion to the materials constituting the insulating layer 4, the case 10, and the support member 7 to the resin material, and thus a chemical bonding or hydrogen bonding-based bonding of the insulating layer 4, the case 10, and the support member 7 to the anode-side electrode layer 12a and the cathode-side electrode layer 12b can be expected.

[0088] ​​Further, it is desirable that the anode-side end surface 4a and the cathode-side end surface 4b of the insulating layer 4, the anode-side end surface 10a and the cathode-side end surface 10b of the exterior body 10, and the anode-side end surface 7a and the cathode-side end surface 7b of the support member 7 each have a surface roughness (Ra) of 5 μm or more. With such a configuration, the contact area of each end surface with the anode-side electrode layer 12a and the cathode-side electrode layer 12b can be increased, and a strong bond based on an anchoring effect can be imparted.

[0089] <Manufacturing method>

[0090] Next, a manufacturing method of a solid electrolytic capacitor according to an embodiment of the present disclosure will be described using Figures 4A-4C and Figures 5A-5C Figures 4A-4C and Figures 5A-5C are cross-sectional views of the solid electrolytic capacitor in each process of the manufacturing method of the solid electrolytic capacitor, respectively.

[0091] (Laminating process)

[0092] First, a laminating process shown in Figure 4A is performed. In the laminating process, the conductive material 8 is applied in an appropriate amount on the support member 7, and one of the plurality of capacitor elements 1 (capacitor element 1c) prepared in advance is placed thereon with high precision.

[0093] Next, the conductive material 8 is applied in an appropriate amount on the capacitor element 1c, and the capacitor element 1b is placed thereon. Further, the conductive material 8 is applied in an appropriate amount on the capacitor element 1b, and the capacitor element 1a is placed thereon.

[0094] As the method of applying the conductive material 8, for example, a known method such as dispensing, printing, inkjet, dipping, or transfer can be appropriately used.

[0095] Then, the conductive material 8 is heat-cured using a high-temperature furnace or the like, and the cathode bodies 6 of the respective capacitor elements 1 are made to be in conduction with each other. In addition, as the means of heat-curing, it is not limited to a high-temperature furnace, and for example, a hot plate or a reflow furnace or the like can be used.

[0096] In addition, in the above description, a case where the capacitor elements 1 are sequentially laminated at one position on the support member 7 is described, but the laminating of a plurality of capacitor elements can be performed simultaneously at a plurality of positions (for example, in a matrix shape of a plurality of columns and a plurality of rows) on the support member 7.

[0097] (Sealing process)

[0098] Next, a sealing process shown in Figure 4B is performed. In the sealing process, as shown in Figure 4B ​As shown, the outer casing 10 seals the entire stacked capacitor element 1. Preferably, the outer casing 10 also fills the gaps between the stacked capacitor elements 1 and between the support member 7 and the capacitor element 1. Alternatively, a resin material different from the outer casing 10 can be pre-filled in the gaps between the stacked capacitor elements 1 and between the support member 7 and the capacitor element 1.

[0099] As a method for sealing capacitor element 1 using outer casing 10, any known method may be used, such as transfer method, compression method, or method of heat curing liquid resin after it has been poured into a mold.

[0100] (End face exposure process)

[0101] Next, proceed Figure 4C The end face exposure process is shown. In the end face exposure process, the anode side of the capacitor element 1 sealed by the outer casing 10 is exposed so that the anode terminal portion 9 is exposed from the outer casing 10. As a result, the anode side end face 14 is formed. In addition, the cathode side is exposed so that the cathode terminal portion 8b is exposed. As a result, the cathode side end face 15 is formed.

[0102] As a method for exposing the end face, for example, one can use a cutting blade with diamond particles fixed by an adhesive material rotating at high speed to cut the capacitor element 1 sealed by the outer casing 10.

[0103] (Contact layer formation process)

[0104] Next, proceed Figure 5A The contact layer forming process is shown. In the contact layer forming process, 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 first roughened. As a result, 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, which will be described later, is strengthened by the anchoring effect. Furthermore, the contact layer 11 is selectively formed only on the surface of the anode terminal portion 9.

[0105] As described above, cold spraying is preferred as the method for forming the contact layer 11. By cold spraying, if Cu particles, which are the material of the contact layer 11, are sprayed onto the anode side end face 14, the Cu particles do not bond with the anode side end face 4a, anode side end face 10a, and anode side end face 7a formed by the resin material, but only bond with the anode terminal portion 9 formed by the metal material.

[0106] More specifically, Cu particles collide with the anode terminal 9 at high speed, breaking through the oxide film on the surface of the anode terminal 9. As a result, the material of the anode terminal 9, namely Al and Cu particles, undergoes plastic deformation at the collision site due to the energy of the collision, forming new surfaces. Through the contact between the new surfaces of Al and Cu particles, an alloy layer based on the metallic bonding of Al and Cu is formed.

[0107] On the anode-side end face 14, the thickness of the anode terminal portion 9 formed by Al is thinner than that of the anode-side end faces 4a, 10a, and 7a formed by resin. Therefore, Cu particles are less likely to adhere to the end face of the anode terminal portion 9, near the upper and lower ends corresponding to the boundary with the resin. Therefore, as... Figure 2 As shown, the cross-sectional shape of the surface 11S in the thickness direction of the anode body 2 is convex in the center. Furthermore, on surface 11S, Cu particles undergo plastic deformation and adhere in a residual solid phase particle shape, thus forming unevenness due to the particle shape. Therefore, surface 11S is given a surface roughness determined by the size of the Cu particles. As described above, the surface roughness (Ra) of 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 about 5 μm to 10 μm in median particle size. Furthermore, it is preferable that the Cu particles are spherical or approximately spherical.

[0108] By setting the median particle size of the Cu particles used to be relatively large, around 5μm to 10μm, the formation of the contact layer 11 based on the cold spray method can be sufficiently accelerated, making it easy to form a good metal bonding state with the anode terminal 9.

[0109] Furthermore, by setting the Cu particles to a spherical or near-spherical shape, sufficient acceleration can be achieved, making it easier to form a good metallic bond with the anode terminal 9. However, when the Cu particles are spherical or other shapes, such as rod-shaped or polyhedral, acute angles are generated on the surface 11S formed according to the particle volume. This makes it easy for cracks originating from acute angles to form at the interface between the contact layer 11 and the anode-side electrode layer 12a formed in the electrode layer formation process described later. In other words, by setting the Cu particles to a spherical or near-spherical shape and forming the surface 11S primarily as a curved surface, cracks are less likely to form.

[0110] By setting the surface roughness of the surface 11S of the contact layer 11 to 3 μm or more, the following effects can be obtained. On the surface 11S side of the contact layer 11, an anode-side electrode layer 12a is formed in the electrode layer formation process described later. Here, the conductive filler such as Ag contained in the anode-side electrode layer 12a has a size of less than about 1 μm. Therefore, by setting the surface roughness of the surface 11S to 3 μm or more, the conductive filler can easily penetrate into the unevenness of the surface 11S. As a result, compared to the case where the surface 11S is formed smoothly, the contact area between the surface 11S and the anode-side electrode layer 12a can be increased, and the contact resistance can be reduced. Furthermore, due to the anchoring effect generated by a portion of the anode-side electrode layer 12a penetrating into the unevenness of the surface 11S, the bonding strength (mechanical strength) between the contact layer 11 and the anode-side electrode layer 12a can be improved.

[0111] Furthermore, in this disclosure, cold spraying is preferred for forming the contact layer 11. However, as mentioned above, other metal film forming methods such as electroplating, dip soldering, sputtering, or vapor deposition can also be used to form the contact layer 11. When using electroplating, Ni with low ionization tendency can be plated onto the Al surface of the anode terminal portion 9. Alternatively, the contact layer 11 can be formed by combining multiple layers, such as Ni+Ag plating. In this case, the cross-sectional shape of the surface 11S in the thickness direction of the anode body 2 is as follows: Figure 3 As shown, it has a roughly straight shape.

[0112] When using metal film formation methods other than cold spraying such as electroplating, dip soldering, sputtering, or vapor deposition, as mentioned above, a physical surface roughening process is required after the metal film is formed. As a roughening method, a blasting method using non-metallic particles such as alumina, sand, or glass can be employed. This method can also form metal films with… Figure 3 The contact layer 11 has the surface roughness shown. Furthermore, by using non-metallic powder with a fine size of 3 μm or more during sandblasting, the surface roughness of surface 11S can be set to 3 μm or more.

[0113] Furthermore, although not illustrated, by filling the insulating layer 4 with insulating resin or the like to improve the sealing performance, it is also possible to prevent the intrusion of electroplating solutions, etc.

[0114] (Electrode layer formation process)

[0115] Next, as Figure 5B As shown, an electrode layer formation process is performed. In this process, an anode-side electrode layer 12a and a cathode-side electrode layer 12b are formed on the anode-side end face 14 and the cathode-side end face 15, respectively. Thus, 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.

[0116] 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 using an impregnation method, a transfer method, a printing method, a dispensing method, or the like, and then curing it by high temperature.

[0117] In addition, the anode-side electrode layer 12a can also cover at least a portion of the upper surface of the exterior body 10 or the lower surface of the support member 7 in addition to the anode-side end surface 14. Similarly, the cathode-side electrode layer 12b can also cover a portion of the upper surface of the exterior body 10 or the lower surface of the support member 7 in addition to the cathode-side end surface 15.

[0118] (External electrode forming step)

[0119] Finally, as shown in FIG. 1C, an external electrode forming step is performed. As shown in FIG. 1D, 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. Figure 5C Figure 5C

[0120] Specifically, the anode-side external electrode 13a and the cathode-side external electrode 13b are formed using a barrel plating method or the like, which is one of electroplating methods. The anode-side external electrode 13a and the cathode-side external electrode 13b are, for example, a laminated structure of Ni and Sn.

[0121] In addition, the anode-side external electrode 13a and the cathode-side external electrode 13b can also be formed to include Ag and Sn using the cold spraying method described above. Alternatively, the anode-side external electrode 13a and the cathode-side external electrode 13b can also be formed by a combination of a barrel plating method and a dip soldering method.

[0122] Further, the anode-side external electrode 13a and the cathode-side external electrode 13b can also be formed by a method in which a Cu material cap on which a Sn film is previously formed is bonded to the anode-side electrode layer 12a and the cathode-side electrode layer 12b formed by Ag paste that functions as an adhesive.

[0123] <Effects>

[0124] The present disclosure can provide a solid electrolytic capacitor in which electrical characteristics and mechanical characteristics are improved, and a manufacturing method thereof.

[0125] ​​The solid electrolytic capacitor 20 according to the embodiment of the present disclosure includes: the capacitor element 1 having the anode body 2, the dielectric oxide film layer 3 covering the anode body 2, and the cathode body 6 formed on the dielectric oxide film layer 3; the outer body 10 covering the capacitor element 1; the contact layer 11 formed on the end portion of the anode body 2, i.e., the anode terminal portion 9, having a surface 11S with a prescribed surface roughness; and the anode-side electrode layer 12 covering the surface 11S.

[0126] Thus, by providing the contact layer 11 that is metal-bonded to the anode terminal portion 9 including the valve action metal foil and has a prescribed surface roughness, the contact area between the contact layer 11 and the anode-side electrode layer 12a is increased. Therefore, the contact resistance between the contact layer 11 and the anode-side electrode layer 12a is reduced, and the joining strength between the contact layer 11 and the anode-side electrode layer 12a is improved. Thus, a low-resistance current path from the anode body 2 to the anode-side external electrode 13a can be ensured, the electrical characteristics of the solid electrolytic capacitor 20 can be improved, and the mechanical strength can be improved, so the reliability is improved.

[0127] In addition, the present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist thereof.

[0128] Industrial Applicability

[0129] The solid electrolytic capacitor of the present disclosure maintains good electrical characteristics, and has high reliability and productivity, and can be applied as a capacitor for all fields such as personal computers, portable terminals, industrial use, in-vehicle use, and the like.

Claims

1. A solid electrolytic capacitor, comprising: A capacitor element has an anode body, a dielectric oxide film covering the anode body, and a cathode body formed on the dielectric oxide film layer; An outer casing that covers the capacitor element; A contact layer is formed on the anode terminal portion, which is the end of the anode body, and has a surface with a specified surface roughness; and Anode-side electrode layer, covering the surface. The anode-side electrode layer comprises a conductive paste material in which metal fillers are mixed into a resin, wherein the size of the metal fillers is smaller than the surface roughness of the contact layer. The specified surface roughness is 3 μm or more.

2. The solid electrolytic capacitor according to claim 1, wherein, The cross-sectional shape of the surface of the anode body in the thickness direction is formed as a centrally convex shape or a generally straight shape.

3. The solid electrolytic capacitor according to claim 1 or 2, wherein, The contact layer is a metal film formed by the accumulation of metal particles on the anode terminal portion.

4. The solid electrolytic capacitor according to claim 3, wherein, The metal particles are spherical or nearly spherical.

5. The solid electrolytic capacitor according to claim 3, wherein, The contact layer is metal-bonded to the anode terminal portion.

6. The solid electrolytic capacitor according to claim 1 or 2, wherein, The contact layer contains a metal with a lower ionization tendency than the anode body.

7. A method for manufacturing a solid electrolytic capacitor, comprising: The process of forming a capacitor element with an anode; The process of covering the capacitor element with an outer casing; The process of exposing the end of the anode body, i.e. the anode terminal portion, from the outer casing; The process of forming a contact layer at the anode terminal portion; The process of forming a specified roughness on the surface of the contact layer; and The process of covering the surface of the contact layer with the anode-side electrode layer. The anode-side electrode layer comprises a conductive paste material in which metal fillers are mixed into a resin, wherein the size of the metal fillers is smaller than the surface roughness of the contact layer. The specified surface roughness is 3 μm or more.

8. The method for manufacturing a solid electrolytic capacitor according to claim 7, wherein, The process of forming the contact layer and the process of forming a specified roughness on the surface of the contact layer are performed in one step.

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