JP2020072185A - Electrolytic capacitor - Google Patents

Abstract

To suppress positional deviation of a cathode lead terminal.SOLUTION: An electrolytic capacitor comprises a capacitor element, an anode lead terminal, a cathode lead terminal and an outer package. A part of a second principal surface of the cathode lead terminal and a bonding surface of the capacitor element are bonded. The cathode lead terminal has a covered part covered with the outer package, and an exposed part exposed from the outer package. The covered part comprises an inner bent part. The inner bent part comprises: a first inner bent part for bending the cathode lead terminal extended from a bonding part with the bonding surface toward a second principal surface side along the capacitor element; and a second inner bent part for bending the cathode lead terminal bent by the first inner bent part toward a first principal surface side to lead out from the outer package. The exposed part comprises a first external bent part for bending the cathode lead terminal led out from the outer package toward the second principal surface side. The cathode lead terminal is formed with a through-hole. The through-hole is formed on the first inner bent part and on the second inner bent part, and is not formed on the exposed part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to electrolytic capacitors, and more particularly to improvements in cathode lead terminals.

  Electrolytic capacitors have a small equivalent series resistance (ESR) and excellent frequency characteristics, and are therefore mounted in various electronic devices. An electrolytic capacitor usually includes a capacitor element having an anode part and a cathode part, an anode lead terminal electrically connected to the anode part, and a cathode lead terminal electrically connected to the cathode part. The capacitor element is usually sealed with an exterior body. The cathode lead terminal is bent once or more and led out from the outer package, and then further bent along the outer shape of the outer package.

  When the cathode lead terminal led out from the outer package is bent along the outer shape of the outer package, stress may be applied to the cathode lead terminal inside the outer package, and the position may shift. When the position of the cathode lead terminal is displaced, a gap is created between the cathode lead terminal and the outer package, or a crack is produced in the outer package. In addition, the position of the cathode lead terminal may be misaligned with the cathode portion of the capacitor element.

  Therefore, some methods have been proposed to reduce the stress applied to the cathode lead terminal during bending. For example, in Patent Document 1, a through hole or a notch is provided in the lead-out portion of the cathode lead terminal extending in the direction toward the outer package. In Patent Document 2, a cutout hole and a protrusion are provided in a portion of the cathode lead terminal along the end face of the capacitor element.

JP, 2010-80600, A Japanese Utility Model Publication No. 3-95621

  In the above method, the effect of suppressing the positional deviation of the cathode lead terminal is not sufficient. In addition, the strength of the cathode lead terminal is likely to decrease.

  A first aspect of the present invention is a capacitor element including an anode part and a cathode part, an anode lead terminal electrically connected to the anode part, and an electrical connection to the cathode part, and a first main surface and the A cathode lead terminal having a second main surface opposite to the first main surface; and an exterior body covering the capacitor element, and a part of the second main surface of the cathode lead terminal and the capacitor element. The joining surface is joined, and the cathode lead terminal has a covering portion that is covered with the outer casing, and an exposed portion that is exposed from the outer casing, and the covering portion includes an inner bent portion. The inner bent portion bends the cathode lead terminal extending from the joint portion with the joint surface toward the second main surface side along the capacitor element, and the first inner bent portion. The cathode lead terminal bent at the bent portion is connected to the first A second internal bending portion that is bent toward the surface side and is led out from the exterior body, and the exposed portion is a first internal bending portion that bends the cathode lead terminal led out from the exterior body toward the second main surface side. An external bent portion is provided, and a through hole penetrating from the first main surface to the second main surface is formed in the cathode lead terminal, and the through hole is formed on the first internal bent portion and the first internal bent portion. 2 The present invention relates to an electrolytic capacitor which is formed on an inner bent portion and is not formed on the exposed portion.

  According to the present invention, the positional deviation of the cathode lead terminal can be suppressed while maintaining the strength of the cathode lead terminal.

It is a cross-sectional schematic diagram of the electrolytic capacitor which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram of the principal part of the electrolytic capacitor which concerns on one Embodiment of this invention. It is a perspective view which shows typically the principal part of the electrolytic capacitor which concerns on one Embodiment of this invention. It is a top view which expands and shows the principal part of the cathode lead terminal shown in FIG.

  The electrolytic capacitor according to the present embodiment includes a capacitor element having an anode part and a cathode part, an anode lead terminal electrically connected to the anode part, and a cathode part electrically connected to the first main surface and the first main surface. A cathode lead terminal having a second main surface opposite to the main surface and an exterior body covering the capacitor element are provided.

  The cathode lead terminal has a through hole penetrating from the first main surface to the second main surface. The through holes are formed on the first inner bent portion and the second inner bent portion. In other words, the through hole is formed so as to straddle the first inner bent portion, and the first through the through hole formed on the first inner bent portion (hereinafter referred to as the first through hole). A part of the internal bend is cut off. Further, the through hole is formed so as to straddle the second inner bent portion, and the through hole formed on the second inner bent portion (hereinafter referred to as the second through hole) allows the second inner portion to be formed. A part of the bent portion is cut off. The inside of the first through hole and the second through hole is filled with a cured product of the exterior body material (hereinafter, may be simply referred to as an exterior body material).

  When forming the first outer bent portion, the cathode lead terminal has a force (stress F1) for pulling the cathode lead terminal toward the outside of the outer package and a force (stress for pushing the cathode lead terminal toward the first main surface side). F2) is applied (see FIG. 2). That is, the cathode lead terminals move due to the stresses F1 and F2, and the positional deviation easily occurs.

  The stresses F1 and F2 particularly act on the first inner bent portion and the second inner bent portion. However, according to the present embodiment, since the first internal bent portion and the second internal bent portion are partially cut by the through holes, stress is unlikely to act on the bent portions. Therefore, the positional deviation of the cathode lead terminal is suppressed, and cracks are less likely to be formed in the outer package. As a result, the increase in ESR is suppressed.

  Furthermore, the first through-hole that straddles the first inner bent portion also reduces the load on the exterior body material near the edge of the capacitor element and the first inner bent portion when forming the first outer bent portion. Therefore, damage to the capacitor element is suppressed and cracks are less likely to be formed in the outer package. The second through hole that straddles the second inner bent portion also reduces the load applied to the exterior body near the second inner bent portion when forming the first outer bent portion. Therefore, the crack of the outer package is further suppressed.

  In addition, the exterior body material on the first main surface side and the exterior body material on the second main surface side of the cathode lead terminal are connected via the exterior body material with which the through hole is filled. Therefore, the cathode lead terminal is firmly fixed, and lateral displacement of the cathode lead terminal and peeling between the cathode lead terminal and the joint surface of the capacitor element are also suppressed.

  However, the through hole is not formed in the exposed portion of the cathode lead terminal. As a result, the strength of the cathode lead terminal in the vicinity of the first outer bent portion is maintained, and damage to the cathode lead terminal during bending processing is suppressed. In particular, the through hole may not be formed on the first outer bent portion. Further, since the cathode lead terminal is formed with the through hole instead of the notch, the strength required for the cathode lead terminal can be more easily ensured.

  An electrolytic capacitor according to an embodiment of the present invention will be described with reference to the drawings as appropriate, but the invention is not limited thereto. FIG. 1 is a schematic cross-sectional view of the electrolytic capacitor according to this embodiment. In FIG. 1, the through holes are omitted for convenience. FIG. 2 is a schematic sectional view of a main part of the electrolytic capacitor according to the embodiment.

  The electrolytic capacitor 20 has a capacitor element 10 having an anode part 6 and a cathode part 7, an outer package 11 that seals the capacitor element 10, an electrical connection with the anode part 6, and a part of the outer package 11. An exposed anode lead terminal 13 and a cathode lead terminal 14 electrically connected to the cathode portion 7 and partially exposed from the outer package 11 are provided. The anode part 6 has an anode body 1 having a dielectric layer 3 and an anode wire 2. The anode wire 2 includes a first portion 2a embedded in the anode body 1 and a second portion 2b extending from the anode body 1. The anode wire 2 is electrically connected to the anode body 1 via the second portion 2b. The cathode part 7 has a solid electrolyte layer 4 formed on the dielectric layer 3, and a cathode layer 5 (carbon layer 5a and metal paste layer 5b) that covers the surface of the solid electrolyte layer 4.

  The cathode lead terminal 14 has a first main surface 14X and a second main surface 14Y opposite to the first main surface 14X. A part of the second main surface 14Y is bonded to one surface (bonding surface 10X) of the capacitor element via the conductive adhesive 8 to electrically connect the cathode lead terminal 14 and the cathode portion 7. The conductive adhesive 8 is, for example, a mixture of a thermosetting resin described later and carbon particles or metal particles.

  One end of the cathode lead terminal 14 is bonded to the bonding surface 10X, for example, and is arranged inside the outer package 11. The other end of the cathode lead terminal 14 is exposed from the outer package 11. That is, the cathode lead terminal 14 includes a covering portion inside the exterior body and an exposed portion outside the exterior body. An inner bent portion 141 is formed on the covering portion, and an outer bent portion 142 is formed on the exposed portion.

  The inner bent portion 141 includes a first inner bent portion 1411 for bending the cathode lead terminal 14 extending from the joint with the joint surface 10X toward the second main surface 14Y side along the capacitor element 10, and a first inner bent portion. The cathode lead terminal 14 bent at the portion 1411 is bent to the first main surface 14X side and is led out from the exterior body 11 by a second internal bent portion 1412. Through holes 140 (first through holes 1401, second through holes 1402) penetrating from the first main surface to the second main surface are formed on the first inner bent portion and the second inner bent portion. ..

  The external bent portion 142 includes a first external bent portion 1421 that bends the cathode lead terminal 14 led out from the outer package 11 toward the second main surface 14Y side. The cathode lead terminal 14 may include a second outer bent portion 1422 that is bent along the first outer bent portion 1421 and then bent along the outer shape of the outer housing 11 toward the mounting surface 11X of the outer housing 11. In this case, a part of the exposed cathode lead terminal 14 is arranged on the mounting surface 11X together with a part of the anode lead terminal 13.

<Cathode lead terminal>
A through hole that penetrates from the first main surface to the second main surface is formed on the first inner bent portion and the second inner bent portion of the cathode lead terminal. A part of the first inner bent portion is cut off by a through hole (hereinafter referred to as a first through hole) formed on the first inner bent portion. A part of the second inner bent portion is cut off by the through hole (hereinafter referred to as the second through hole) formed on the second inner bent portion.

  In terms of ensuring the strength of the cathode lead terminal in the first outer bent portion, the length L11 from the first outer bent portion to the through hole is 75% of the length L1 from the first outer bent portion to the second inner bent portion. It may be 100% or less. In this case, when the first outer bent portion and further the second outer bent portion are formed, it is easier to suppress cracking or cutting of the cathode lead terminal. The ratio of the length L11 to the length L1 (L11 / L1) may be 80% or more. L11 / L1 may be 90% or less. When L11 / L1 is 100%, the point closest to the first outer bent portion on the outer edge of the through hole is on the second inner bent portion.

  The length L11 is the length in the longitudinal direction A from the first outer bent portion to a point on the outer edge of the through hole (for example, the second through hole) closest to the first outer bent portion. The length L1 is an average value of the lengths in the longitudinal direction A of the cathode lead terminal at any three positions in the region from the second inner bent portion to the first outer bent portion.

  The length (W11) from one end portion (first end portion) in the width direction B perpendicular to the longitudinal direction A of the cathode lead terminal to the first through hole (W11) is equal to that of the cathode lead terminal in the vicinity of the first internal bent portion. It may be 10% or more and 40% or less of the length (W1) in the width direction B. The ratio of W11 to W1 (W11 / W1) may be 12% or more, and may be 20% or more. W11 / W1 may be 35% or less, and may be 25% or less. W11 / W1 may be 12% or more and 35% or less, and may be 20% or more and 25% or less.

  When the ratio of the width W11 to the width W1 is 10%, the strength of the cathode lead terminal in the vicinity of the first inner bent portion is easily secured. Therefore, when forming the first outer bent portion, the stress applied to the first inner bent portion can be appropriately resisted, and the effect of suppressing the positional deviation of the cathode lead terminal is further enhanced. When the ratio of the width W11 to the width W1 is 40%, the stress applied to the first inner bent portion when forming the first outer bent portion is small, and the effect of suppressing the positional deviation of the cathode lead terminal is higher. Become.

  The width W11 is the length in the width direction B from the first end portion to the outer edge of the first through hole closest to the first end portion. The width W12 described later is similarly obtained. The width W1 is the length from the first end portion to the second end portion in a cross section obtained by cutting the cathode lead terminal in the width direction B so as to pass through the first inner bent portion. The width W2 described later is similarly obtained.

  The above relationship may be satisfied by at least the first end of both ends in the width direction B of the cathode lead terminal. Both ends in the width direction B of the cathode lead terminal may satisfy the above relationship in that strength is more easily secured. What is the length from the first end of the cathode lead terminal to the outer edge of the first through hole closest to this and the length from the other end (second end) to the outer edge of the first through hole closest to this? , May be the same or different. The length from the first end may be the same as the length from the second end in that the stress during bending is likely to be applied evenly to the cathode lead terminal.

  The length (width W12) from the first end of the cathode lead terminal to the outer edge of the second through hole in the width direction B is the length (width W2) of the cathode lead terminal in the width direction B in the vicinity of the second inner bent portion. May be 10% or more and 40% or less. The ratio of the width W12 to the width W2 (W12 / W2) may be 12% or more, and may be 20% or more. W12 / W2 may be 35% or less, and may be 25% or less. W12 / W2 may be 12% or more and 35% or less, and may be 20% or more and 25% or less.

  When the ratio of the width W12 to the width W2 is 10% or more, the strength of the cathode lead terminal in the vicinity of the second inner bent portion is easily secured. Therefore, when forming the first outer bent portion, the stress applied to the second inner bent portion can be appropriately resisted, and the effect of suppressing the positional deviation of the cathode lead terminal is further enhanced. When the ratio of the width W12 to the width W2 is 40% or less, the stress applied to the second inner bent portion becomes smaller when the first outer bent portion is formed, and the effect of suppressing the positional deviation of the cathode lead terminal is further improved. Get higher

  The above relationship may be satisfied by at least the first end of both ends in the width direction B of the cathode lead terminal. Both ends in the width direction B of the cathode lead terminal may satisfy the above relationship in that strength is more easily secured. Even if the length from the first end of the cathode lead terminal to the outer edge of the second through hole closest thereto is the same as the length from the second end to the outer edge of the second through hole closest to this Good or different. Since the stress during bending is easily applied to the cathode lead terminal evenly, the length from the first end to the outer edge of the second through hole closest to this and the second through hole closest to this from the second end. To the outer edge of the may be the same. The width W1 and the width W2 may be the same or different.

  Plural first through holes and second through holes may be formed. One through hole may be formed so as to straddle the first inner bent portion and the second inner bent portion. In this case, the through hole is part of the region (first region) facing the bonding surface of the cathode lead terminal and the region (second region) between the second inner bent portion and the first outer bent portion. It may be formed in a strip shape so as to cut out the part and a part of the region between the first region and the second region. The strip-shaped through hole may be formed so as not to cut off the first outer bent portion. A plurality of strip-shaped through holes may be formed along the longitudinal direction of the cathode lead terminal. The cathode lead terminal may have a third through hole other than the first through hole, the second through hole, and the band-shaped through hole.

  When the third through hole is formed, the length from the first end of the cathode lead terminal to the outer edge of the third through hole is the width direction of the cathode lead terminal in order to secure the strength of the cathode lead terminal. It may be 10% or more and 40% or less of the length of B. The length in the width direction B of the cathode lead terminal is an average value of the lengths in the width direction B at any three positions of the cathode lead terminal.

  The longitudinal direction of the cathode lead terminal is the direction of a straight line that connects the center points that bisect the length of the short side in two opposing short sides of the cathode lead terminal before bending. Specifically, the first region of the cathode lead terminal is a region from the first inner bent portion to the inner end of the cathode lead terminal.

  From the viewpoint of suppressing the positional deviation and maintaining the strength, the opening area of all the through holes formed in the covering portion of the cathode lead terminal is 5% or more and 30% or less of the area of the first main surface in the covering portion. It may be 8% or more and 25% or less.

  The area of the first main surface in the covering portion is, for example, the area of the first main surface in the region from the end portion (internal end portion) located inside the exterior body of the cathode lead terminal to the first outer bent portion. .. The area of the first main surface is an area assuming that there is no through hole.

  The shape of the through hole viewed from the normal direction of the first main surface is not particularly limited, and may be, for example, a circle, an ellipse, a rectangle, a rectangle with rounded corners, or a track shape (straight lines parallel to each other and end portions of these straight lines It may be a shape composed of two connecting curves) or other polygons. The through hole is formed in the inner region not including the outer edge of the cathode lead terminal, and its shape is clearly defined. This is different from the notch formed by cutting out a part of the outer edge of the cathode lead terminal.

  The material of the cathode lead terminal is not particularly limited as long as it is electrochemically and chemically stable and has conductivity. The cathode lead terminal may be a metal such as copper or a nonmetal. According to this embodiment, since the positional deviation of the cathode lead terminal is suppressed by the action of the through hole, the cathode lead terminal made of a material having low wettability of the outer casing material (for example, gold-plated copper) should be used. You can

  The shape of the cathode lead terminal is not particularly limited and is, for example, a long and flat plate shape. The thickness T of the cathode lead terminal may be 25 μm or more and 200 μm or less, or 25 μm or more and 100 μm or less from the viewpoint of reducing the height.

FIG. 3 is a perspective view schematically showing an example of a main part of one embodiment. In FIG. 3, the exterior body and the conductive adhesive are omitted for convenience.
FIG. 4 is a developed top view showing the essential parts of the cathode lead terminal shown in FIG.

  The cathode lead terminal 14 is formed with a through hole 140 penetrating from the first main surface 14X to the second main surface 14Y. The through hole 140 is formed in a strip shape so as to cut out a part of the first region, a part of the second region, and a part of the region between the first region and the second region of the cathode lead terminal 14. Has been done. Due to the through hole 140, parts of the first inner bent portion 1411 and the second inner bent portion 1412 are cut off.

  The length in the width direction B from the first inner bent portion 1411 to the first outer bent portion 1421 of the cathode lead terminal 14 is constant, and the length of the cathode lead terminal 14 in the width direction B in the vicinity of the first inner bent portion 1411. The width (W1) is equal to the length (W2) of the cathode lead terminal 14 in the width direction B near the second inner bent portion 1412. The through hole 140 has a substantially rectangular shape, and the opening width in the width direction B is substantially constant. One end of the through hole 140 in the longitudinal direction A is on the first region, and the other end is on the second region.

  In the vicinity of the first inner bent portion 1411, the length (W11a) from the first end portion 14a of the cathode lead terminal 14 to the outer edge of the through hole 140 is 15% or more of the width W1 (W) of the cathode lead terminal 14, 24 % Or less. The length (W11b) from the second end portion 14b of the cathode lead terminal 14 to the outer edge of the through hole 140 is also 15% or more and 24% or less of the width W1 (W) of the cathode lead terminal 14.

  In the vicinity of the second inner bent portion 1412, the length (W12a) from the first end portion 14a of the cathode lead terminal 14 to the through hole 140 is 15% or more and 24% or less of the width W2 (W) of the cathode lead terminal 14. Is. The length (W12b) from the second end portion 14b of the cathode lead terminal 14 to the through hole 140 is also 15% or more and 24% or less of the width W2 (W) of the cathode lead terminal 14.

  The through hole that straddles the first outer bent portion 1421 is not formed. The third through hole is also not formed. The length L11 from the first outer bent portion 1421 to the outer edge of the through hole 140 is 80% or more and 90% or less of the length L1 from the first outer bent portion 1421 to the second inner bent portion 1412. The opening area of the through hole 140 in the first region of the cathode lead terminal 14 is 8% or more and 25% or less of the area of the first main surface 14X in the first region.

<Capacitor element>
Hereinafter, the capacitor element according to the present embodiment will be described in detail, taking as an example a case where a solid electrolyte layer is provided as an electrolyte.
(Anode part)
The anode part has an anode body and an anode wire extending from one surface of the anode body and electrically connected to the anode lead terminal.
The anode body is, for example, a rectangular parallelepiped porous sintered body obtained by sintering metal particles. As the metal particles, particles of valve action metal such as titanium (Ti), tantalum (Ta), niobium (Nb) are used. One type or two or more types of metal particles are used for the anode body. The metal particles may be an alloy composed of two or more kinds of metals. For example, an alloy containing a valve metal and silicon, vanadium, boron or the like can be used. Alternatively, a compound containing a valve metal and a typical element such as nitrogen may be used. The alloy of the valve action metal contains the valve action metal as a main component and contains, for example, 50 atom% or more of the valve action metal.

  The anode wire is made of a conductive material. The material of the anode wire is not particularly limited, and examples thereof include copper, aluminum, and aluminum alloys in addition to the above valve action metal. The materials forming the anode body and the anode wire may be the same or different. The anode wire has a first portion embedded from one surface of the anode body into the inside of the anode body, and a second portion extending from the one surface of the anode body. The sectional shape of the anode wire is not particularly limited, and examples thereof include a circle, a track shape, an ellipse, a rectangle, and a polygon.

  The anode part is manufactured, for example, by pressure-molding a rectangular parallelepiped in a state where the first part is embedded in the powder of the metal particles, and sintering. As a result, the second portion of the anode wire is pulled out from one surface of the anode body so as to stand. The second portion is joined to the anode lead terminal by welding or the like, and the anode wire and the anode lead terminal are electrically connected. The welding method is not particularly limited, and examples thereof include resistance welding and laser welding.

  A dielectric layer is formed on the surface of the anode body. The dielectric layer is made of, for example, a metal oxide. As a method of forming a layer containing a metal oxide on the surface of the anode body, for example, a method of anodizing the surface of the anode body by dipping the anode body in a chemical conversion solution, or the anode body under an atmosphere containing oxygen. The method of heating is mentioned. The dielectric layer is not limited to the layer containing the above metal oxide, and may have an insulating property.

(Cathode part)
The cathode part has a solid electrolyte layer formed on the dielectric layer and a cathode layer covering the solid electrolyte layer.
The solid electrolyte layer may be formed so as to cover at least a part of the dielectric layer. For the solid electrolyte layer, for example, a manganese compound or a conductive polymer is used. Examples of the conductive polymer include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyparaphenylenevinylene, polyacene, polythiophenvinylene, polyfluorene, polyvinylcarbazole, polyvinylphenol, polypyridine, and derivatives of these polymers. Can be mentioned. These may be used alone or in combination of two or more. Further, the conductive polymer may be a copolymer of two or more kinds of monomers. Polythiophene, polyaniline, and polypyrrole may be used because of their excellent conductivity. In particular, polypyrrole may be used because of its excellent water repellency.

  The solid electrolyte layer containing the conductive polymer is formed, for example, by polymerizing a raw material monomer on the dielectric layer. Alternatively, it is formed by applying a liquid containing the conductive polymer to the dielectric layer. The solid electrolyte layer is composed of one or more solid electrolyte layers. When the solid electrolyte layer is composed of two or more layers, the composition and forming method (polymerization method) of the conductive polymer used in each layer may be different.

  In the present specification, polypyrrole, polythiophene, polyfuran, polyaniline and the like mean polymers having a basic skeleton of polypyrrole, polythiophene, polyfuran, polyaniline and the like, respectively. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline and the like may include their respective derivatives. For example, polythiophene includes poly (3,4-ethylenedioxythiophene) and the like.

  Various dopants may be added to the polymerization liquid for forming the conductive polymer, the solution or the dispersion liquid of the conductive polymer in order to improve the conductivity of the conductive polymer. Although the dopant is not particularly limited, 1,5-naphthalenedisulfonic acid, 1,6-naphthalenedisulfonic acid, 1-octanesulfonic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 2-methyl-5-isopropylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, 4-nitrotoluene-2-sulfonic acid, m-nitrobenzenesulfonic acid, n-octylsulfonic acid, n-butane Sulfonic acid, n-hexanesulfonic acid, o-nitrobenzenesulfonic acid, p-ethylbenzenesulfonic acid, trifluoromethanesulfonic acid, hydroxybenzenesulfonic acid, butylnaphthalenesulfonic acid, benzenesulfonic acid, polystyrenesulfonic acid, polyvinylsulfone Acid, methanesulfonic acid, and, derivatives thereof, and the like. Examples of the derivative include metal salts such as lithium salt, potassium salt and sodium salt, ammonium salts such as methylammonium salt, dimethylammonium salt and trimethylammonium salt, piperidinium salt, pyrrolidinium salt and pyrrolinium salt.

  When the conductive polymer is dispersed in the dispersion medium in the form of particles, the average particle diameter D50 of the particles is, for example, 0.01 μm or more and 0.5 μm or less. When the average particle diameter D50 of the particles is within this range, the particles easily penetrate into the inside of the anode body.

  The cathode layer has, for example, a carbon layer formed so as to cover the solid electrolyte layer, and a metal paste layer formed on the surface of the carbon layer. The carbon layer contains a conductive carbon material such as graphite and a resin. The metal paste layer contains, for example, metal particles (for example, silver) and a resin. The configuration of the cathode layer is not limited to this configuration. The cathode layer may have any structure as long as it has a current collecting function.

<Anode lead terminal>
The anode lead terminal is electrically connected to the anode body through the second portion of the anode wire. The material of the anode lead terminal is not particularly limited as long as it is electrochemically and chemically stable and has conductivity. The anode lead terminal may be a metal such as copper or a nonmetal. The shape is not particularly limited as long as it is flat. The thickness of the anode lead terminal (the length between the main surfaces of the anode lead terminal) may be 25 μm or more and 200 μm or less, or 25 μm or more and 100 μm or less from the viewpoint of reducing the height.

  One end of the anode lead terminal may be joined to the anode wire by a conductive adhesive or solder, or may be joined to the anode wire by resistance welding or laser welding. The other end of the anode lead terminal is exposed from the exterior body. A part of the exposed portion of the anode lead terminal is arranged on the mounting surface together with the cathode lead terminal.

<Exterior body>
The outer package is provided to electrically insulate the anode lead terminal and the cathode lead terminal, and is made of an insulating material (exterior body material). The exterior body material includes, for example, a thermosetting resin. Examples of the thermosetting resin include epoxy resin, phenol resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane, polyimide and unsaturated polyester.

<< Manufacturing method of electrolytic capacitor >>
An example of the method of manufacturing the electrolytic capacitor according to this embodiment will be described.

(1) Preparation Step First, a capacitor element is prepared.
The valve action metal particles and the anode wire are put into a mold so that the first part is embedded in the valve action metal particles, pressure-molded, and then sintered in a vacuum, whereby the first part is made of a porous sintered body. An anode part to be embedded inside is prepared from one surface. The pressure at the time of pressure molding is not particularly limited and is, for example, about 10 N or more and 100 N or less. The valve action metal particles may be mixed with a binder such as polyacrylic carbonate, if necessary.

  Next, a dielectric layer is formed on the anode body. Specifically, the anode body is immersed in a chemical conversion tank filled with an electrolytic aqueous solution (for example, phosphoric acid aqueous solution), and the second portion of the anode wire is connected to the anode body of the chemical conversion tank to perform anodization. Thus, the dielectric layer made of the oxide film of the valve metal can be formed on the surface of the anode body. The electrolytic aqueous solution is not limited to the phosphoric acid aqueous solution, and nitric acid, acetic acid, sulfuric acid or the like can be used.

Then, a solid electrolyte layer is formed. In this embodiment, a process of forming the solid electrolyte layer 4 containing a conductive polymer will be described.
The solid electrolyte layer containing a conductive polymer is, for example, a method of impregnating an anode body on which a dielectric layer is formed with a monomer or an oligomer, and then polymerizing the monomer or oligomer by chemical polymerization or electrolytic polymerization, or The anode body on which the body layer is formed is impregnated with a solution or dispersion liquid of a conductive polymer and dried to form it on at least a part of the dielectric layer.

Finally, a carbon paste and a metal paste are sequentially applied to the surface of the solid electrolyte layer to form a cathode layer composed of the carbon layer and the metal paste layer. The structure of the cathode layer is not limited to this, and may be any structure having a current collecting function.
The capacitor element is manufactured by the above method.

  Secondly, an anode lead terminal and a cathode lead terminal are prepared. A through hole is formed at a predetermined position of the cathode lead terminal. The position of the through hole is appropriately set according to the shape and size of the capacitor element. However, the through holes are formed so as to be arranged on the first inner bent portion and the second inner bent portion. The position of each internal bent portion is appropriately set according to the shape and size of the capacitor element.

  On the cathode lead terminal, the first inner bent portion and the second inner bent portion are formed. The internal bent portion is formed by, for example, press working. An internal bent portion is also formed on the anode lead terminal. The position of the internal bent portion of the anode lead terminal may be appropriately set according to the length and diameter of the anode wire.

(2) Lead Terminal Joining Step The anode lead terminal and the cathode lead terminal are arranged at predetermined positions. At this time, a conductive adhesive is applied to a predetermined position on the cathode layer.

  The capacitor element is mounted from the second main surface side of the cathode lead terminal in a state where each lead terminal is arranged. Next, the second portion of the anode wire and the vicinity of one end of the anode lead terminal are joined by laser welding or resistance welding. At this time, the vicinity of one end of the cathode lead terminal is joined to the cathode layer via a conductive adhesive.

(3) Sealing Step The materials of the capacitor element and the outer casing (for example, uncured thermosetting resin and filler) are housed in a mold, and the capacitor element is sealed by a transfer molding method, a compression molding method, or the like. At this time, a part of the anode lead terminal and the cathode lead terminal is exposed from the mold. The molding conditions are not particularly limited, and the time and temperature conditions may be appropriately set in consideration of the curing temperature of the thermosetting resin used.

(4) Bending process After the capacitor element covered with the outer package is taken out from the mold, the parts of the anode lead terminal and the cathode lead terminal exposed from the mold are bent along the guides, and each is bent outside. To form a part. Thereby, a part of the anode lead terminal and the cathode lead terminal is arranged on the mounting surface of the outer package.
The electrolytic capacitor is manufactured by the above method.

  Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
An electrolytic capacitor was produced according to the following procedure.
<Step 1: Formation of anode body>
Tantalum metal particles were used as the valve metal. The tantalum metal particles were formed into a rectangular parallelepiped so that one end of the anode wire made of copper was embedded in the tantalum metal particles, and then the formed body was sintered in vacuum. As a result, an anode part including an anode body made of a porous sintered body of tantalum and an anode wire having one end embedded in the anode body and the remaining portion erected from one surface of the anode body was obtained.

<Step 2: Formation of dielectric layer>
The anode body and a part of the anode wire erected from the anode body were immersed in a chemical conversion tank filled with a phosphoric acid aqueous solution which was an electrolytic aqueous solution, and the other end of the anode wire was connected to the anode body of the chemical conversion tank. Then, by performing anodization, a uniform dielectric of tantalum oxide (Ta ₂ O ₅ ) is formed on the surface of the anode body (the surface of the porous sintered body including the inner wall surface of the hole) and a part of the surface of the anode wire. A body layer was formed. The anodic oxidation was performed for 2 hours under the conditions of a conversion voltage of 10 V and a temperature of 60 ° C. in an anode body in a 0.02 mass% phosphoric acid aqueous solution.

<Step 3: Formation of solid electrolyte layer>
A mixed solution was prepared by dissolving pyrrole and polystyrene sulfonic acid as a dopant in ion-exchanged water. While stirring the obtained mixed solution, ferric sulfate and sodium persulfate dissolved in ion-exchanged water were added to carry out a polymerization reaction. After the reaction, the obtained reaction solution was dialyzed to remove unreacted monomer and excess oxidizing agent, to obtain a dispersion liquid containing polypyrrole doped with about 3.0% by mass of polystyrenesulfonic acid. The obtained dispersion was impregnated into the anode body on which the dielectric layer was formed for 5 minutes and then dried at 150 ° C. for 30 minutes to form a solid electrolyte layer on the dielectric layer.

<Step 4: Formation of cathode layer>
The carbon layer was formed by applying a carbon paste on the surface of the solid electrolyte layer. Next, a silver paste layer was formed by applying a silver paste on the surface of the carbon layer. Thus, the cathode layer composed of the carbon layer and the silver paste layer was formed.

<Step 5: Preparation of lead terminal>
A gold-plated copper plate was prepared and punched into the shapes of an anode lead terminal and a cathode lead terminal. At this time, a substantially rectangular through hole shown in FIG. 4 was formed at a predetermined position of the cathode lead terminal. Subsequently, an internal bent portion was formed on each lead terminal by pressing.

<Step 6: Fabrication of electrolytic capacitor>
After applying the conductive adhesive to the cathode layer, the cathode lead terminal was bonded to the cathode layer via the conductive adhesive. The anode wire and the anode lead terminal were joined by resistance welding.
Next, the material of the capacitor element and the outer package (the uncured thermosetting resin and the filler) to which the lead terminals were joined were housed in a mold, and the capacitor element was sealed by a transfer molding method.
Finally, the portions of the anode lead terminal and the cathode lead terminal exposed from the mold were bent along a guide to form an external bent portion. Thereby, a part of the anode lead terminal and the cathode lead terminal was arranged on the mounting surface of the outer package. In this way, five electrolytic capacitors were manufactured.

  The length L11 from the first outer bent portion to the through hole is about 83% of the length L1 from the first outer bent portion to the second inner bent portion. The width W11 (width W11a and width W11b) from the end of the cathode lead terminal in the longitudinal direction A to the through hole formed on the first inner bent portion is about 12.5% of the width W1 of the cathode lead terminal. is there. The width W12 (width W12a and width W12b) from the end of the cathode lead terminal in the longitudinal direction A to the through hole formed on the second inner bent portion is about 12.5% of the width W2 of the cathode lead terminal. is there. The opening area of the through hole is about 22% of the area of the first main surface of the covering portion.

<Airtightness evaluation>
The airtightness of each of the obtained electrolytic capacitors was evaluated according to the following criteria using a liquid immersion test method according to JIS Z 2330: 2012. However, a solvent (perfluoropolyether) was used as the liquid. The electrolytic capacitor in which bubble leakage is observed is presumed to have damage such as cracks on the exterior body. The results are shown in Table 1.

(Evaluation criteria)
0/5: No bubble leak was observed from any electrolytic capacitor 1/5: Bubble leak was observed from one electrolytic capacitor out of 5 2/5: Two electrolytic capacitors out of 5 5/5: Bubble leak was observed from all electrolytic capacitors

[Example 2]
In Step 5, five electrolytic capacitors were manufactured in the same manner as in Example 1 except that the ratio of the width W11 (width W12) to the width W1 (width W2) was set to about 16.7%, and the airtightness was improved. evaluated. The results are shown in Table 1. The opening area of the through hole is about 20% of the area of the first main surface of the covering portion.

[Example 3]
In Step 5, five electrolytic capacitors were manufactured in the same manner as in Example 1 except that the ratio of the width W11 (width W12) to the width W1 (width W2) was set to about 20.1%, and the airtightness was improved. evaluated. The results are shown in Table 1. The opening area of the through hole is about 17% of the area of the first main surface of the covering portion.

[Example 4]
In Step 5, five electrolytic capacitors were manufactured in the same manner as in Example 1 except that the ratio of the width W11 (width W12) to the width W1 (width W2) was set to about 25%, and the airtightness was evaluated. . The results are shown in Table 1. The opening area of the through hole is about 15% of the area of the first main surface of the covering portion.

[Example 5]
In Step 5, five electrolytic capacitors were manufactured in the same manner as in Example 1 except that the ratio of the width W11 (width W12) to the width W1 (width W2) was set to about 33.3%, and the airtightness was improved. evaluated. The results are shown in Table 1. The opening area of the through hole is approximately 10% of the area of the first main surface of the covering portion.

[Example 6]
In Step 5, five electrolytic capacitors were manufactured in the same manner as in Example 1 except that the ratio of the width W11 (width W12) to the width W1 (width W2) was set to about 37.5%, and the airtightness was improved. evaluated. The results are shown in Table 1. The opening area of the through hole is about 7% of the area of the first main surface of the covering portion.

[Comparative Example 1]
In Step 5, five electrolytic capacitors were manufactured and evaluated in the same manner as in Example 1 except that the through holes were not formed. The results are shown in Table 1.

  Examples 1 to 6 have excellent airtightness. In particular, Examples 1 to 5 have high airtightness. After polishing the vicinity of the cathode lead terminal of the electrolytic capacitors of Examples 1 to 6 with a cross-section polisher and observing with a scanning electron microscope (SEM), no crack was confirmed in the outer package near the cathode lead terminal. On the other hand, Comparative Example 1 is inferior in airtightness. When the cross section of the electrolytic capacitor of Comparative Example 1 was observed in the same manner, cracks were confirmed in the outer package near the cathode lead terminal. It is considered that this is because the through hole was not formed on the first inner bent portion, and therefore the stress acted more strongly on the first inner bent portion when forming the first outer bent portion.

  INDUSTRIAL APPLICABILITY The electrolytic capacitor according to the present invention can be used in various applications because the positional deviation of the cathode lead terminal is suppressed.

20: Electrolytic capacitor 10: Capacitor element 10X: Bonding surface 1: Anode body 2: Anode wire 2a: First portion 2b: Second portion 3: Dielectric layer 4: Solid electrolyte layer 5: Cathode layer 5a: Carbon layer 5b: Metal Paste layer 6: Anode part 7: Cathode part 8: Conductive adhesive 11: Outer package 11X: Mounting surface 13: Anode lead terminal 14: Cathode lead terminal 14X: First main surface 14Y: Second main surface 14a: First End 14b: Second end 140: Through hole 1401: First through hole 1402: Second through hole 141: Internal bent portion 1411: First internal bent portion 1412: Second internal bent portion 142: External bent portion 1421: First external bending portion 1422: Second external bending portion

Claims (6)

A capacitor element having an anode part and a cathode part;
An anode lead terminal electrically connected to the anode part,
A cathode lead terminal that is electrically connected to the cathode portion and has a first main surface and a second main surface opposite to the first main surface;
An exterior body covering the capacitor element,
A part of the second main surface of the cathode lead terminal and a bonding surface of the capacitor element are bonded,
The cathode lead terminal has a coating portion coated on the exterior body, and an exposed portion exposed from the exterior body,
The covering portion includes an internal bent portion,
The internal bent portion includes a first internal bent portion that bends the cathode lead terminal extending from the bonded portion with the bonded surface toward the second main surface along the capacitor element, and the first internal bent portion. A second inner bent portion that bends the cathode lead terminal bent at a portion to the first main surface side and leads out from the exterior body,
The exposed portion includes a first external bending portion that bends the cathode lead terminal led out from the outer package to the second main surface side,
The cathode lead terminal is formed with a through hole penetrating from the first main surface to the second main surface,
The electrolytic capacitor, wherein the through hole is formed on the first inner bent portion and the second inner bent portion, and is not formed on the exposed portion.   The length from the first outer bent portion to the through hole is 75% or more and 100% or less of the length from the first outer bent portion to the second inner bent portion. Electrolytic capacitor.   The length from one end portion in the width direction perpendicular to the longitudinal direction of the cathode lead terminal to the through hole formed on the first inner bent portion is the length in the width direction of the cathode lead terminal. 10% or more and 40% or less of the electrolytic capacitor according to claim 1 or 2.   The length from one end in the width direction perpendicular to the longitudinal direction of the cathode lead terminal to the through hole formed on the second inner bent portion is the length in the width direction of the cathode lead terminal. 10% or more and 40% or less of the electrolytic capacitor according to any one of claims 1 to 3.   The cathode lead terminal includes a second outer bent portion that bends the cathode lead terminal bent at the first outer bent portion along an outer shape of the outer body toward a mounting surface of the outer body. The electrolytic capacitor according to any one of 1 to 4.   The through-hole has a part of a first region facing a bonding surface of the cathode lead terminal, a part of a second region between the second inner bent part and the first outer bent part, and the first hole. The electrolytic capacitor according to claim 1, wherein the electrolytic capacitor is formed in a band shape so as to cut out a part of a region between one region and the second region.

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