electrolytic capacitor

Abstract

This electrolytic capacitor 1 comprises: a laminate 30 which has a first surface 30a and in which a plurality of capacitor elements 20 are laminated, each capacitor element including a valve action metal substrate 4 having a core portion 4a and a porous portion 4b formed along the surface of the core portion, a dielectric layer 5 formed on the porous portion 4b, a solid electrolyte layer 7a formed on the dielectric layer 5, and a conductive layer 7b formed on the solid electrolyte layer 7a; a first conductive resin part 21 which is provided on the first surface 30a of the laminate 30, and to which the core portion 4a of the capacitor element 20 is connected; and a first lead frame 11 connected to the core portion 4a with the first conductive adhesive part 21 therebetween.

Description

[Technical Field]

[0001] The present invention relates to an electrolytic capacitor. [Background technology]

[0002] Patent Document 1 discloses a solid electrolytic capacitor. The second embodiment of the solid electrolytic capacitor disclosed in Patent Document 1 describes a structure in which three chip-type solid electrolytic capacitors are stacked together, with an anode lead exposed from each capacitor element and an anode terminal joined to the anode lead by laser welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-85273 Summary of the Invention [Problem to be solved by the invention]

[0004] The anode lead of the solid electrolytic capacitor in Patent Document 1 is made of valve metal. A component called a lead frame is used as the anode terminal. When the valve metal serving as the anode lead and the lead frame serving as the anode terminal are welded together as in Patent Document 1, the bond is hard and the joint lacks flexibility. Therefore, stress caused by thermal expansion of each component during reflow can cause the bond between the lead frame and the valve metal to come loose, resulting in problems such as an increase in LC (leakage current) in the electrolytic capacitor.

[0005] The present invention has been made to solve the above problems, and aims to provide an electrolytic capacitor in which the lead frame and valve metal are electrically connected and stresses such as thermal stresses are alleviated. [Means for solving the problem]

[0006] The electrolytic capacitor of the present invention comprises a valve action metal substrate having a core portion and a porous portion formed along its surface, a laminate having a first surface in which a plurality of capacitor elements are stacked, each capacitor element including a dielectric layer formed on the porous portion, a solid electrolyte layer formed on the dielectric layer, and a conductive layer formed on the solid electrolyte layer, a first conductive resin portion provided on the first surface of the laminate and to which the core portion of the capacitor element is connected, and a first lead frame connected to the core portion via the first conductive resin portion. [Effects of the Invention]

[0007] According to the present invention, an electrolytic capacitor can be provided in which the lead frame and the valve metal are electrically connected and stresses such as thermal stresses are alleviated. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view schematically illustrating an example of an electrolytic capacitor of the present invention. [Figure 2] FIG. 2 is a side view of the electrolytic capacitor shown in FIG. 1 as seen from the first end surface. [Figure 3] FIG. 3 is a bottom view of the electrolytic capacitor shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the electrolytic capacitor shown in FIG. 1 taken along line AA. [Figure 5] FIG. 5 is a cross-sectional view schematically showing the vicinity of the valve metal substrate on the first surface of the laminate. [Figure 6] FIG. 6 is a process diagram that schematically shows part of the manufacturing process of an electrolytic capacitor. [Figure 7] FIG. 7 is a process diagram that schematically shows part of the manufacturing process of an electrolytic capacitor. [Figure 8A] FIG. 8A is a process diagram schematically illustrating a part of the manufacturing process of an electrolytic capacitor. [Figure 8B] FIG. 8B is a process diagram that schematically shows a part of the manufacturing process of the electrolytic capacitor. [Figure 9A]FIG. 9A is a process diagram schematically illustrating a part of the manufacturing process of an electrolytic capacitor. [Figure 9B] FIG. 9B is a process diagram schematically showing a part of the manufacturing process of the electrolytic capacitor. [Figure 9C] FIG. 9C is a process diagram schematically showing a part of the manufacturing process of the electrolytic capacitor. [Figure 10] FIG. 10 is a cross-sectional view of an electrolytic capacitor according to another embodiment taken along the LT plane. [Figure 11] FIG. 11 is a cross-sectional view of an electrolytic capacitor according to another embodiment taken along the LT plane. [Figure 12] FIG. 12 is a process diagram schematically illustrating a part of the manufacturing process of the electrolytic capacitor shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] The solid electrolytic capacitor of the present invention will now be described. However, 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 of the present invention described below.

[0010] The electrolytic capacitor of the present invention comprises a valve action metal substrate having a core portion and a porous portion formed along its surface, a laminate having a first surface in which a plurality of capacitor elements are stacked, each capacitor element including a dielectric layer formed on the porous portion, a solid electrolyte layer formed on the dielectric layer, and a conductive layer formed on the solid electrolyte layer, a first conductive resin portion provided on the first surface of the laminate and to which the core portion of the capacitor element is connected, and a first lead frame connected to the core portion via the first conductive resin portion.

[0011] FIG. 1 is a perspective view schematically showing an example of an electrolytic capacitor of the present invention, FIG. 2 is a side view of the electrolytic capacitor shown in FIG. 1 as seen from a first end face, and FIG. 3 is a bottom view of the electrolytic capacitor shown in FIG. 1.

[0012] 1, 2 and 3 show an electrolytic capacitor 1. The electrolytic capacitor 1 has a rectangular parallelepiped shape as a whole, and has a length direction (L direction), a width direction (W direction), and a thickness direction (T direction). The electrolytic capacitor 1 has, as its outer surfaces, a first end face 1a and a second end face 1b that face each other in the length direction. The electrolytic capacitor 1 also has, as its outer surfaces, a bottom face 1c and a top face 1d that face each other in the thickness direction. The electrolytic capacitor 1 also has, as its outer surfaces, a first side face 1e and a second side face 1f that face each other in the width direction.

[0013] In this specification, the surface extending along the length direction (L direction) and thickness direction (T direction) of the electrolytic capacitor is referred to as the LT surface, the surface extending along the length direction (L direction) and width direction (W direction) is referred to as the LW surface, and the surface extending along the width direction (W direction) and thickness direction (T direction) is referred to as the WT surface.

[0014] A first lead frame 11 is formed on a first end face 1a of the electrolytic capacitor 1, and a second lead frame 13 is formed on a second end face 1b. The first lead frame 11 is formed continuously from the first end face 1a to the bottom face 1c of the electrolytic capacitor 1, and the second lead frame 13 is formed continuously from the second end face 1b to the bottom face 1c of the electrolytic capacitor 1.

[0015] In electrolytic capacitor 1, the periphery of a laminate (not shown in FIG. 1) in which multiple capacitor elements are stacked is sealed with sealing resin 8, and a rectangular parallelepiped resin molding 9 is formed, with the surface of sealing resin 8, the surface of first lead frame 11, and the surface of second lead frame 13 being the outer surfaces.

[0016] The surface of the first lead frame 11, together with the surface of the sealing resin 8, constitutes the first end face 1a of the electrolytic capacitor 1 (see FIG. 2). The surface of the second lead frame 13, together with the surface of the sealing resin 8, constitutes the second end face 1b of the electrolytic capacitor 1. Furthermore, the surface of first lead frame 11, the surface of sealing resin 8, and the surface of second lead frame 13 together form bottom surface 1c of electrolytic capacitor 1 (see FIG. 3).

[0017] In the electrolytic capacitor of the present invention, it is preferable that the periphery of the laminate is sealed with a sealing resin, and that the surface of the sealing resin and the surface of the first lead frame form an outer surface of a rectangular parallelepiped resin molded body. Also, in the electrolytic capacitor of the present invention, it is preferable that the periphery of the laminate is sealed with a sealing resin, and that the surface of the sealing resin, the surface of the first lead frame, and the surface of the second lead frame form an outer surface of a rectangular parallelepiped resin molded body.

[0018] The shape of the electrolytic capacitor of the present invention and the shape of the resin molded body constituting the electrolytic capacitor of the present invention are not particularly limited, and any three-dimensional shape can be adopted. The shape of the electrolytic capacitor and the shape of the resin molded body are preferably rectangular parallelepiped. Furthermore, rectangular parallelepiped does not mean a perfect rectangular parallelepiped, and the surfaces forming the electrolytic capacitor and the resin molded body may be tapered and not perpendicular to other surfaces, or may have chamfered corners.

[0019] FIG. 4 is a cross-sectional view of the electrolytic capacitor shown in FIG. 1 taken along line AA. Capacitor element 20 includes a valve metal substrate 4 having a core portion and a porous portion formed along the surface of the core portion, a dielectric layer 5 formed on the porous portion, a solid electrolyte layer 7a formed on dielectric layer 5, and a conductive layer 7b (carbon layer 7b1 and metal layer 7b2) formed on solid electrolyte layer 7a. A plurality of capacitor elements 20 are stacked to form a laminate 30, and the periphery of the laminate 30 is sealed with a sealing resin 8 to form a resin molded body 9. In the laminate 30, the stacked capacitor elements 20 may be bonded to each other via a conductive adhesive (not shown).

[0020] Examples of the valve metal constituting the valve metal substrate include simple metals such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, and silicon, as well as alloys containing these metals. Among these, aluminum and aluminum alloys are preferred.

[0021] The shape of the valve metal substrate is not particularly limited, but is preferably a flat plate, more preferably a foil, and the porous portion is preferably an etching layer that has been etched with hydrochloric acid or the like. The thickness of the valve metal substrate before etching is preferably 60 μm or more and 180 μm or less. Furthermore, the thickness of the unetched valve metal substrate (core portion) after etching is preferably 10 μm or more and 70 μm or less. The thickness of the porous portion is designed according to the withstand voltage and capacitance required for the electrolytic capacitor, and the combined thickness of the porous portions on both sides of the valve metal substrate is preferably 10 μm or more and 120 μm or less.

[0022] The dielectric layer is preferably made of an oxide film of the valve metal. For example, when an aluminum foil is used as the valve metal substrate, an oxide film serving as the dielectric layer can be formed by anodizing the aluminum foil in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or their sodium salts or ammonium salts. The dielectric layer is formed along the surface of the porous portion, forming pores (recesses). The thickness of the dielectric layer is designed according to the withstand voltage and capacitance required for the electrolytic capacitor, but is preferably 3 nm or more and 200 nm or less.

[0023] At the anode side end of the capacitor element 20, a mask layer 40 is provided around the valve metal substrate 4 and the dielectric layer 5. A portion of the surface of the mask layer 40, together with the surfaces of the core and porous portions of the valve metal substrate 4, constitutes the first surface 30a of the laminate 30. The first surface 30a of the laminate 30 corresponds to the first end face 1a of the electrolytic capacitor 1. The first surface 30a of the laminate 30 is the anode side end face of the laminate.

[0024] First conductive resin portions 21 are provided on the first surface 30a of the laminate 30, to which the core portions of the capacitor elements 20 are connected. Since the first conductive resin portions 21 to which the core portions of the capacitor elements 20 are connected are integrated, current is collected from the anodes of the plurality of capacitor elements 20 by the first conductive resin portions 21.

[0025] First conductive resin portion 21 is further connected to first lead frame 11. Since first conductive resin portion 21 is connected to the core of capacitor element 20 and first lead frame 11, first lead frame 11 is connected to the core of capacitor element 20 via first conductive resin portion 21.

[0026] In the electrolytic capacitor of the present invention, the first lead frame and the core of the capacitor element are not welded but are connected via the first conductive resin portion. Because the connection via the first conductive resin portion is a resin connection, the joint is more flexible than welding. This prevents defects caused by the first lead frame and the core being separated due to stress caused by thermal expansion of each component during reflow. Furthermore, since the first conductive resin portion is made of a conductive material, electrical connection between the first lead frame and the core is also ensured. As a result, the electrolytic capacitor of the present invention has electrical connection between the first lead frame and the valve metal, and is an electrolytic capacitor that is stress-relieved against stresses such as thermal stress.

[0027] The first lead frame may be made of aluminum, copper, nickel, chromium, cobalt, or an alloy containing any of these.

[0028] The first conductive resin portion is preferably a conductive resin electrode layer containing a conductive component and a resin component. The conductive component preferably contains Ag, Cu, Ni, Sn, or the like as a main component, and the resin component preferably contains epoxy resin, phenol resin, or the like as a main component. In particular, it is preferable that the first conductive resin portion contains Ag. When the conductive resin electrode layer contains Ag, the ESR can be reduced because Ag has a low specific resistance. The first conductive resin portion is preferably a printed resin electrode layer formed by screen printing an electrode paste. When the first conductive resin portion is a printed resin electrode layer, the first conductive resin portion can be made flatter than when an electrode layer is formed by dipping into an electrode paste. Moreover, instead of screen printing, the first conductive resin portion may be formed by applying electrode paste using a dispenser.

[0029] The electrode paste for forming the first conductive resin portion may contain an organic solvent, and the organic solvent is preferably a glycol ether-based solvent, such as diethylene glycol monobutyl ether or diethylene glycol monophenyl ether. If necessary, additives may be used, which are useful for adjusting the rheology of the electrode paste, particularly the thixotropy.

[0030] It is preferable that a contact layer be provided on the first surface of the laminate in direct contact with the core portion, and that the core portion be connected to the first conductive resin portion via the contact layer. Hereinafter, a description will be given of a configuration in which the core portion is connected to the first conductive resin portion via a contact layer.

[0031] FIG. 5 is a cross-sectional view schematically showing the vicinity of the valve metal substrate on the first surface of the laminate. FIG. 5 is also a cross-sectional view that schematically shows the area surrounded by the dotted line B in the lower right portion of FIG. The valve metal substrate 4 has a core 4a and a porous portion 4b formed along the surface of the core 4a. An end of the valve metal substrate 4 is exposed on the first surface 30a of the laminate 30. A dielectric layer 5 is formed on the surface of the porous portion 4b.

[0032] 5 shows the contact layer 31 in direct contact with the core portion 4a. The first conductive resin portion 21 is present around the contact layer 31, and the core portion 4a is connected to the first conductive resin portion 21 via the contact layer 31. The contact layer 31 is preferably an electrode layer containing at least one selected from the group consisting of Cu, Ni, Sn, Ag, Zn, and Au, and is preferably an electrode layer made of Cu.

[0033] By providing a contact layer, the connectivity between the core and the first conductive resin can be improved. For example, if the core is made of aluminum and the main conductive component contained in the first conductive resin is Ag, the connectivity may be improved by connecting the aluminum and Ag via another material rather than directly connecting them. For example, using Cu or Zn for the contact layer and connecting the aluminum and Ag via Cu or Zn can improve the connectivity between the aluminum core and the first conductive resin containing Ag.

[0034] Furthermore, it is preferable that the thickness of the contact layer 31 in the core portion 4a is greater than the thickness of the contact layer 31 in the porous portion 4b. The thickness of the contact layer 31 is defined as the thickness of the contact layer 31 in the normal direction to the first surface 30a of the laminate 30. The thicknesses of the contact layers 31 formed in the core portion 4a of the valve metal substrate 4 and in the porous portion 4b of the valve metal substrate 4 are defined as the thicknesses at their thickest points. In Fig. 5, the thicknesses of the contact layers 31 formed in the core portion 4a of the valve metal substrate 4 and in the porous portion 4b of the valve metal substrate 4 are indicated by double-headed arrows T1 and T2. The directions indicated by the double-headed arrows T1 and T2 are normal directions to the first surface 30a of the laminate 30.

[0035] When forming the contact layer 31 on the first surface 30a of the laminate 30, the contact layer 31 is easily formed in the core portion 4a, but is less likely to be formed in the porous portion 4b, which is more fragile than the core portion 4a. As a result, the thickness of the contact layer 31 is greater in the core portion 4a. When the thickness of the contact layer is thicker in the core portion, the contact area with the first conductive resin portion formed on the contact layer increases compared to when the contact layer is flat, improving the adhesion with the first conductive resin portion and making it possible to sufficiently reduce the ESR. Furthermore, since the connection strength between the contact layer and the first conductive resin portion is high, the terminal fixing strength when an electrolytic capacitor is mounted can also be increased.

[0036] The thickness of the contact layer formed in the core is preferably 0.3 μm or more and 30 μm or less. When the thickness of the contact layer is in this range, the ESR can be further reduced, and the terminal fixing strength when the electrolytic capacitor is mounted can be further increased.

[0037] The contact layer is preferably a layer formed by aerosol deposition, in which metal particles are sprayed from a nozzle at the tip of an aerosol generator and collide with the first surface of the laminate to form the contact layer. In the aerosol deposition method, the aerosol impinges on the core, removing the oxide film on the metal surface that makes up the core, exposing the metal, and then bonding the contact layer to the exposed metal. In the aerosol deposition method, the removal of the oxide film and the bonding of the contact layer are carried out consecutively in a non-oxidizing atmosphere, preventing the formation of an oxide film at the bonding interface between the contact layer and the core. Furthermore, the resistance at the bonding interface between the contact layer and the core is low, which helps to reduce the ESR of the electrolytic capacitor. In particular, when the valve metal substrate is aluminum, an oxide film is likely to form on the surface of the core, and therefore the effect of providing a contact layer by the aerosol deposition method is particularly favorable.

[0038] As a method for providing the contact layer, in addition to the aerosol deposition method, methods such as sputtering and vapor deposition can also be used.

[0039] Up to this point, the configuration related to the anode of the electrolytic capacitor has been described. Next, the configuration related to the cathode of the electrolytic capacitor and other components of the electrolytic capacitor will be described with reference to FIG.

[0040] Capacitor element 20 includes a solid electrolyte layer 7a formed on dielectric layer 5 and a conductive layer 7b formed on solid electrolyte layer 7a. An electrolytic capacitor in which a solid electrolyte layer is provided as part of the cathode can be said to be a solid electrolytic capacitor.

[0041] The cathode side end of the valve metal substrate 4 constituting the capacitor element 20 is insulated by being covered with a dielectric layer 5, for example, so that the core 4a of the valve metal substrate 4 is not in direct contact with the solid electrolyte layer 7a or the conductive layer 7b.

[0042] Examples of materials constituting the solid electrolyte layer include conductive polymers with a skeleton of pyrroles, thiophenes, anilines, etc. Examples of conductive polymers with a skeleton of thiophenes include PEDOT [poly(3,4-ethylenedioxythiophene)], which may be PEDOT:PSS, which is a composite of PEDOT and polystyrene sulfonic acid (PSS) as a dopant.

[0043] The solid electrolyte layer is formed, for example, by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the dielectric layer using a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or by a method of applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer and drying it. Note that it is preferable to form an inner solid electrolyte layer that fills the pores (recesses) and then form an outer solid electrolyte layer that covers the entire dielectric layer. The solid electrolyte layer can be formed in a predetermined region by applying the treatment liquid or dispersion onto the dielectric layer by sponge transfer, screen printing, spray coating, dispenser, inkjet printing, etc. The thickness of the solid electrolyte layer is preferably 2 μm or more and 20 μm or less.

[0044] The conductive layer is preferably a carbon layer, a graphene layer, or a silver layer formed by applying a conductive paste such as a carbon paste, a graphene paste, or a silver paste. Alternatively, the conductive layer may be a composite layer in which a silver layer is provided on a carbon layer or a graphene layer, or a mixed layer in which a carbon paste or a graphene paste is mixed with a silver paste.

[0045] The conductive layer can be formed by applying a conductive paste such as carbon paste onto the solid electrolyte layer by sponge transfer, screen printing, spray coating, dispenser, inkjet printing, or the like. FIG. 4 shows a carbon layer 7b1 and a metal layer 7b2 as the conductive layer 7b.

[0046] It is preferable that the electrolytic capacitor of the present invention further comprises a second conductive resin portion provided on the second surface of the laminate and to which the conductive layer of the capacitor element is connected, and a second lead frame connected to the second conductive resin portion.

[0047] 4, a second conductive resin portion 23 is formed on the second surface 30b of the laminate 30, and the second conductive resin portion 23 is connected to the conductive layer 7b of the capacitor element 20. The second conductive resin portions 23 to which the conductive layers 7b of the capacitor elements 20 are connected are integrated, and therefore the cathodes of the multiple capacitor elements 20 are collected by the second conductive resin portion 23. The second surface 30b of the laminate 30 is the cathode side end face of the laminate.

[0048] Second conductive resin portion 23 is further connected to second lead frame 13. Since second conductive resin portion 23 is connected to conductive layer 7b of capacitor element 20 and second lead frame 13, second lead frame 13 is connected to conductive layer 7b of capacitor element 20 via second conductive resin portion 23.

[0049] The connection between the second lead frame and the conductive layer of the capacitor element can also be achieved by directly bonding the second lead frame and the conductive layer of the capacitor element without using the second conductive resin portion. However, when the second lead frame and the conductive layer of the capacitor element are directly bonded, the bonding area may be insufficient, resulting in high resistance between the second lead frame and the conductive layer of the capacitor element. On the other hand, when the connection between the second lead frame and the conductive layer of the capacitor element is achieved via the second conductive resin portion, the second conductive resin portion can penetrate into the gaps between the capacitor elements, thereby increasing the connection area between the second conductive resin portion and the conductive layer of the capacitor element. The connection area between the second conductive resin portion and the second lead frame is also increased. This reduces the resistance between the second lead frame and the conductive layer of the capacitor element. Furthermore, since the connection is via resin, the joint is more flexible than welding. This prevents defects caused by the bond between the second lead frame and the conductive layer being separated due to stress caused by thermal expansion of each component during reflow.

[0050] The second lead frame can be made of the same material and have the same shape as the first lead frame, and the second lead frame and the first lead frame may be made of the same material and have different shapes.

[0051] The second conductive resin portion can be a conductive resin electrode layer containing a conductive component and a resin component, as exemplified as the form of the first conductive resin portion. The second conductive resin portion and the first conductive resin portion may be the same in material and shape or may be different.

[0052] Furthermore, a contact layer does not need to be provided on the second surface of the laminate, because in many cases, the connectivity between the conductive layer and the second conductive resin portion can be sufficiently ensured without providing a contact layer.

[0053] The method for extracting the cathode from the capacitor element in the electrolytic capacitor of the present invention is not limited to the method using the second conductive resin part and the second lead frame, and other conventionally known extraction methods may be used, such as a method in which a metal foil is used as a conductive layer to be extracted to the end face of the resin molded body, and then a cathode external electrode consisting of a resin electrode layer and a plating layer is formed.

[0054] It is preferable that a first conductive resin part and a first lead frame are provided on a first surface of a laminate in which multiple capacitor elements are stacked, and that a second conductive resin part and a second lead frame are further provided on a second surface of the laminate as required, and that the periphery is further sealed with a sealing resin, so that the entire structure forms a rectangular parallelepiped resin molded body.

[0055] The encapsulating resin constituting the resin molded body contains at least a resin, and preferably contains a resin and a filler. The resin is preferably an insulating resin such as an epoxy resin, a phenolic resin, a polyimide resin, a silicone resin, a polyamide resin, or a liquid crystal polymer. The encapsulating resin may be in the form of either a solid or liquid resin. The filler is preferably inorganic particles such as silica particles, alumina particles, or metal particles. It is more preferable to use a material containing silica particles in a solid epoxy resin and a phenolic resin. As a molding method for the resin molded body, when a solid encapsulant is used, it is preferable to use a resin mold such as a compression mold or a transfer mold, and it is more preferable to use a compression mold, and when a liquid encapsulant is used, it is preferable to use a molding method such as a dispensing method or a printing method.

[0056] In the electrolytic capacitor obtained in this manner, in a cross section (LT cross section) of the electrolytic capacitor cut along the length and thickness directions, it is preferable that the first lead frame has an L-shape with the first end surface (anode side end surface) of the electrolytic capacitor as the long side. The short side of the L-shape forms the bottom surface of the electrolytic capacitor, which serves as the mounting surface when the electrolytic capacitor is mounted on a substrate, etc. It is preferable that the length of the short side of the L-shape is long enough so that the area of ​​the first lead frame on the bottom surface of the electrolytic capacitor is large enough for mounting.

[0057] In addition, in a cross section (LT cross section) of the electrolytic capacitor cut along the length and thickness directions, the second lead frame preferably has an L-shape with the second end face (cathode side end face) of the electrolytic capacitor as the long side.

[0058] Fig. 4 shows a cross-sectional view of the electrolytic capacitor taken along the LT plane, in which the first lead frame 11 and the second lead frame 13 each have an L-shape in the LT cross section of the electrolytic capacitor. 4, the short sides of the L-shaped first lead frame 11 are drawn to be in contact with the first conductive resin portion 21, the mask layer 40, and the sealing resin 8. The sealing resin 8 may be inserted between the mask layer 40 and the first lead frame 11, and the mask layer 40 and the first lead frame 11 may be bonded via the sealing resin 8. In FIG. 4, the first lead frame 11 has an inverted L shape with the short side facing left, but this shape is also included in the L shape.

[0059] Next, an example of a method for manufacturing an electrolytic capacitor will be described. 6, 7, 8A, 8B, 9A, 9B, and 9C are process diagrams that schematically show part of the manufacturing process of an electrolytic capacitor. 6 shows lead frame runs for use in manufacturing three electrolytic capacitors: a first lead frame run 110 on the right and a second lead frame run 120 on the left. The first lead frame series 110 is provided with plate-shaped portions 111 that become the first lead frames of the electrolytic capacitor, and connecting portions 112 that connect the plate-shaped portions 111. There are three plate-shaped portions 111, and each plate-shaped portion 111 is coated with a conductive paste 113 that becomes the first conductive resin portion. The second lead frame series 120 is provided with plate-shaped portions 121 that become the second lead frames of the electrolytic capacitor, and connecting portions 122 that connect the plate-shaped portions 121. There are three plate-shaped portions 121, and each plate-shaped portion 121 is coated with conductive paste 123 that becomes the second conductive resin portion.

[0060] FIG. 7 shows a state in which the laminate 30 is placed on the first lead frame series 110 and the second lead frame series 120. As shown in FIG. The laminate 30 is placed between a plate-like portion 111 that will become a first lead frame and a plate-like portion 121 that will become a second lead frame. A contact layer that is in direct contact with the core portion is preferably provided on the first surface 30a of the laminate 30. The contact layer is not shown in the drawings.

[0061] Fig. 8A shows a state in which the plate-shaped portion 111 of the first lead frame series 110 and the plate-shaped portion 121 of the second lead frame series 120 are bent toward the first surface 30a and the second surface 30b of the laminate 30, respectively. Fig. 8B is a side view of the state of Fig. 8A as seen from the side of the laminate 30. Since the conductive paste is applied to each plate-like portion, the end faces of the laminate and the plate-like portions are connected by the conductive paste. The plate-like portion 111 of the first lead frame series 110 becomes the first lead frame 11, and the conductive paste 113 becomes the first conductive resin portion 21. The plate-like portion 121 of the second lead frame series 120 becomes the second lead frame 13, and the conductive paste 123 becomes the second conductive resin portion .

[0062] Fig. 9A shows a state in which the periphery of the laminate 30 is sealed with sealing resin 8 to form a resin molded body 9. Fig. 9B is a side view of the state in Fig. 9A seen from the side of the resin molded body 9, and Fig. 9C is an end view of the state in Fig. 9A seen from the first end face side of the resin molded body 9. In FIG. 9B, the stacked body 30 inside the sealing resin 8 is simply shown by dotted lines. As shown in FIG. 9C, first lead frame 11 is exposed at the first end surface of resin molding 9. After going through the steps up to this point, the electrolytic capacitor is in a state in which the lead frame series is connected at the connecting portions, and by cutting the connecting portions, the electrolytic capacitor can be obtained as individual pieces.

[0063] (Another embodiment of the electrolytic capacitor) FIG. 10 is a cross-sectional view of an electrolytic capacitor according to another embodiment taken along the LT plane. In electrolytic capacitor 201 shown in FIG. 10, among capacitor elements 20 constituting laminate 30, capacitor element 220 located closest to the bottom surface has a thick mask layer 240. Further, near the second surface 30b of the laminate 30, a cathode-side spacer 250 is provided below (on the bottom side of) the capacitor element 220 located closest to the bottom side. The cathode side spacer 250 is preferably made of an insulating resin material.

[0064] The mask layer 240 and the cathode-side spacer 250 are provided below (on the bottom side of) the bottommost capacitor element 220, thereby increasing the distance between the bottommost capacitor element 220 and the bottom surface 1c of the electrolytic capacitor 201. This prevents contact and short-circuiting between the first lead frame 11 located on the bottom surface 1c of the electrolytic capacitor 201 and the conductive layer 7b of the bottommost capacitor element 220.

[0065] Furthermore, by adopting such a structure for preventing short circuits, the length of the short side of the L-shape of first lead frame 11 can be increased, and the area of ​​first lead frame 11 on bottom surface 1c of electrolytic capacitor 201 can be made large enough for mounting. At the same time, conductive layer 7b of capacitor element 20 can be provided as close as possible to first surface 30a of laminate 30, thereby increasing the capacitance of the electrolytic capacitor. The cathode side spacer 250 is provided to match the height with the anode side.

[0066] FIG. 11 is a cross-sectional view of an electrolytic capacitor according to another embodiment taken along the LT plane. In the electrolytic capacitor 202 shown in FIG. 11, a cathode-side spacer 250 is provided near the second surface 30b of the laminate 30 for the capacitor element 220 located closest to the bottom surface of the capacitor elements 20 constituting the laminate 30, and an anode-side spacer 260 is provided near the first surface 30a of the laminate 30. The cathode side spacer 250 and the anode side spacer 260 are preferably made of an insulating resin material.

[0067] 10, the cathode-side spacer 250 and the anode-side spacer 260 are provided below (on the bottom side of) the bottommost capacitor element 220, thereby preventing contact and short-circuiting between the first lead frame 11 and the conductive layer 7b of the bottommost capacitor element 220. Other effects are also similar.

[0068] In the case of electrolytic capacitor 202 shown in FIG. 11, the capacitor element 220 located on the bottom side can have the same specifications (same mask layer specifications) as the other capacitor elements 20, which is advantageous over electrolytic capacitor 201 shown in FIG. 10 in that there is no need to prepare a capacitor element with a thick mask layer.

[0069] FIG. 12 is a process diagram schematically illustrating a part of the manufacturing process of the electrolytic capacitor shown in FIG. 12 shows lead frame strings for use in manufacturing three electrolytic capacitors. On the right is a first lead frame string 110, and on the left is a second lead frame string 120, which are similar to the lead frame strings shown in FIG. Spacer paste 270 is applied to the connecting portions 112 of the first lead frame series 110 and the connecting portions 122 of the second lead frame series 120 at positions where the laminate will be placed. By placing the bottom surface of the laminate at the position where the spacer paste 270 is applied, cathode side spacers 250 and anode side spacers 260 can be provided. The steps after placing the laminate are the same as those described above, and an electrolytic capacitor can be manufactured.

[0070] Furthermore, when manufacturing the electrolytic capacitor 201 shown in FIG. 10, the cathode side spacer 250 can be provided by applying spacer paste 270 only to the connecting portion 122 of the second lead frame series 120. The spacer paste preferably has a composition containing an insulating and adhesive resin material. [Explanation of symbols]

[0071] 1 electrolytic capacitor 1a First end face of electrolytic capacitor 1b Second end face of electrolytic capacitor 1c Bottom of electrolytic capacitor 1d Top of electrolytic capacitor 1e Electrolytic Capacitor First Side The second side of the 1f electrolytic capacitor 4. Valve metal substrate 4a Core 4b Porous part 5 Dielectric Layer 7a Solid electrolyte layer 7b Conductive layer 7b1 carbon layer 7b2 metal layer 8 Sealing resin 9. Resin molding 11 First lead frame 13 Second lead frame 20 Capacitor element 21 First conductive resin part 23 Second conductive resin part 30 laminate 30a: First surface of laminate 30b Second surface of laminate 31 Contact layer 40 mask layers 110 First lead frame 111 Plate-shaped part 112 Connection part 113 Conductive Paste 120 Second lead frame series 121 Plate-shaped part 122 Connection section 123 Conductive Paste 201, 202 Electrolytic capacitors 220 Capacitor element located on the bottom side 240 Mask layer of the capacitor element located on the bottom side 250 Cathode spacer 260 Anode side spacer 270 Spacer paste

Claims

1. a laminate having a first surface, in which a plurality of capacitor elements are laminated, each capacitor element including a valve metal substrate having a core portion and a porous portion formed along the surface of the core, a dielectric layer formed on the porous portion, a solid electrolyte layer formed on the dielectric layer, and a conductive layer formed on the solid electrolyte layer; a first conductive resin portion provided on the first surface of the laminate and connected to the core portion of the capacitor element; a first lead frame connected to the core portion via the first conductive resin portion, a mask layer is provided around the valve metal substrate and the dielectric layer at an end of the capacitor element on the first surface side; a part of a surface of the mask layer, together with surfaces of the core portion and the porous portion, constitutes the first surface of the laminate; An electrolytic capacitor, wherein a contact layer is provided on the first surface of the laminate, the core portion, the porous portion, and the mask layer, and the core portion is connected to the first conductive resin portion via the contact layer.

2. 2. The electrolytic capacitor according to claim 1, wherein the contact layer is an electrode layer containing at least one selected from the group consisting of Cu, Ni, Sn, Ag, Zn, and Au.

3. 2. The electrolytic capacitor according to claim 1, wherein the contact layer is an electrode layer made of Cu.

4. 4. The electrolytic capacitor according to claim 1, wherein the thickness of the contact layer at the portion where the contact layer is formed in the core portion is greater than the thickness of the contact layer at the portion where the contact layer is formed in the porous portion.

5. 4. The electrolytic capacitor according to claim 1, wherein the first conductive resin portion to which the core portions of the plurality of capacitor elements are connected is integrated.

6. 4. The electrolytic capacitor according to claim 1, wherein in a cross section of the electrolytic capacitor cut along its length and thickness, the first lead frame has an L-shape with the first end surface of the electrolytic capacitor as the long side.

7. 4. An electrolytic capacitor according to claim 1, wherein the laminate is sealed with a sealing resin, and the surface of the sealing resin and the surface of the first lead frame form an outer surface of a rectangular parallelepiped resin molded body.

8. The electrolytic capacitor according to any one of claims 1 to 3, further comprising: a second conductive resin portion provided on the second surface of the laminate and to which the conductive layer of the capacitor element is connected; and a second lead frame connected to the second conductive resin portion.

9. 9. The electrolytic capacitor according to claim 8, wherein the periphery of the laminate is sealed with a sealing resin, and the surface of the sealing resin, the surface of the first lead frame, and the surface of the second lead frame form an outer surface of a rectangular resin molded body.

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