JP2012069714A - Solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor in which ESR is reduced.SOLUTION: The solid electrolytic capacitor 110 includes a capacitor element 100 where a positive electrode metal piece 4 constituting a positive electrode is connected to a positive electrode body end 1c, i.e. the end of a positive electrode body 1, a dielectric layer consisting of an oxide film is formed on the surface of the positive electrode body at least in the central region 1a thereof, and then a solid electrolyte layer, a graphite layer and a silver paste layer are formed sequentially on the dielectric layer, and a planar positive electrode external terminal 6. The positive electrode metal piece is connected to the positive electrode external terminal with a conductive adhesive 5 interposed therebetween. The positive electrode body end is bent in the direction of the positive electrode external terminal, and that angle is 15°-30°.

Description

  The present invention relates to a solid electrolytic capacitor.

  Along with the higher frequency of electronic devices, capacitors that are one of electronic components are also required to have better equivalent series resistance (ESR) characteristics in the higher frequency region than the prior art. In order to meet the demand, various solid electrolytic capacitors using a conductive polymer having high electrical conductivity as a solid electrolyte have been studied.

  In order to realize low ESR in such a situation, Patent Document 1 proposes a three-terminal solid electrolytic capacitor.

  Hereinafter, the conventional technique shown in Patent Document 1 will be described with reference to the drawings. FIG. 2 is a diagram showing an example of a conventional three-terminal solid electrolytic capacitor, FIG. 2 (a) is a cross-sectional view illustrating a capacitor element, and FIG. 2 (b) is a cross-sectional view illustrating a solid electrolytic capacitor. It is.

  As shown in FIG. 2 (a), a conventional capacitor element 200 has a dielectric layer formed on the surface of an anode body 1 made of a valve action metal foil whose surface has been expanded by etching or the like. A solid electrolyte layer made of a conductive polymer layer is formed in the central region 1a of the anode body 1 on which the layer is formed, and a cathode layer 2 is formed by sequentially forming a graphite layer and a silver paste layer on the surface of the solid electrolyte layer. .

  Further, the dielectric layer formed on both ends of the anode body 1 extending further outward than the resist forming portion 1b on which the resist layer 3 made of epoxy resin or the like is formed is removed with a laser or the like to remove the anode body end portion 1c. Then, the capacitor element 200 is manufactured. Subsequently, the plate-like anode metal piece 4 is connected to the anode body end 1c of the capacitor element 200 by welding or the like.

  Next, as shown in FIG. 2 (b), the exterior resin case 8 has an anode external terminal 6 and a cathode external terminal 7 that are flat and formed on the same plane as the substrate mounting surface. The gap is formed between the cathode external terminal 7 and the bottom resin portion that is mechanically connected, and has a side wall perpendicular to the plane.

  On the surface of the anode external terminal 6 and the surface of the cathode external terminal 7 exposed inside the exterior resin case 8, the anode metal piece 4 and the cathode layer 2 connected to the anode body end portion 1c of the capacitor element 200 are electrically conductive. Each is connected by an adhesive 5. Thereafter, the upper periphery of the outer resin case 8 is covered with a lid 9 and bonded with an adhesive 10 to form a solid electrolytic capacitor 210.

JP 2006-128247 A

  In the above situation, if the connection resistance between the anode part and the conductive adhesive to be connected is large, the problem is that ESR increases, and due to the increase in connection resistance, heat is generated when current flows, and the solid There was a concern that the conductive polymer that is the electrolyte forming the electrolyte layer would undergo oxidative degradation (lower conductivity) and further increase ESR. Therefore, an object of the present invention is to review the connection structure at the end of the anode body of the capacitor element, and to provide a solid electrolytic capacitor with reduced ESR without adding components or complicating the manufacturing process.

  A plate-like or foil-like surface-enhanced valve metal is used as an anode body, and anode metal pieces constituting the anode part are connected to the anode body end part which is an end part of the anode body, and at least in the central region of the anode body A capacitor element in which a dielectric layer made of an oxide film is formed on the surface, a solid electrolyte layer, a graphite layer, and a silver paste layer are sequentially formed on the dielectric layer, and a plate-like anode external terminal, and an anode metal piece Is a solid electrolytic capacitor connected to the anode external terminal via the conductive adhesive, and the anode body end to which the anode metal piece is connected is bent in the direction of the anode external terminal, so that the conductive adhesive and It has been found that the adhesion area of the material increases and ESR decreases.

  That is, in the solid electrolytic capacitor of the present invention, a plate-like or foil-like expanded valve action metal is used as an anode body, and an anode metal piece constituting the anode part is attached to the end of the anode body that is the end of the anode body. A dielectric layer made of an oxide film is formed on the surface of at least the central region of the anode body, and a cathode layer in which a solid electrolyte layer, a graphite layer, and a silver paste layer are sequentially formed on the surface of the dielectric layer. A solid electrolytic capacitor comprising a capacitor element, a plate-like anode external terminal and a cathode external terminal, wherein the anode metal piece and the cathode layer are connected to the anode external terminal and the cathode external terminal via a conductive adhesive. The end of the anode body is bent in the direction of the anode external terminal.

  Further, the angle at which the end of the anode body is bent in the direction of the anode external terminal is 15 ° to 30 °.

  According to the present invention, by bending the anode body end of the capacitor element in the direction of the anode external terminal, the adhesion area between the anode metal piece and the conductive adhesive applied to the surface of the external anode terminal is increased. There is an effect that the resistance of the portion decreases. In addition, heat generation is suppressed when a current flows, and the conductive polymer that is the electrolyte that forms the solid electrolyte layer is prevented from oxidatively degrading (conductivity decreases), thereby enabling low ESR. A solid electrolytic capacitor can be provided.

  Further, since the bonding area between the anode metal piece and the conductive adhesive applied to the surface of the external anode terminal is increased, the angle at which the anode body end is bent toward the anode external terminal is preferably 15 ° to 30 °. .

  Furthermore, according to the present invention, it is possible to provide a solid electrolytic capacitor with reduced ESR without revising the addition of components or complicating the manufacturing process by reviewing the connection structure at the end of the anode body of the capacitor element. become.

It is a figure explaining the solid electrolytic capacitor of this invention, Fig.1 (a) is sectional drawing of a capacitor | condenser element, FIG.1 (b) is sectional drawing of a solid electrolytic capacitor. It is a figure explaining the solid electrolytic capacitor of a prior art example, FIG. 2 (a) is sectional drawing of a capacitor | condenser element, FIG.2 (b) is sectional drawing of a solid electrolytic capacitor.

  An embodiment of the present invention will be described with reference to the drawings by taking a three-terminal solid electrolytic capacitor as an example.

  FIG. 1A is a cross-sectional view illustrating a capacitor element according to the embodiment, and FIG. 1B is a cross-sectional view illustrating a solid electrolytic capacitor.

  First, as shown in FIG. 1 (a), a dielectric layer is formed on the surface of an anode body 1 made of a valve metal foil or plate whose surface has been enlarged about 200 times by etching or the like. A resist forming portion in which a solid electrolyte layer made of a conductive polymer layer, a graphite layer, and a silver paste layer are sequentially formed in the central region 1a of the body 1 to form a cathode layer 2 and a resist layer 3 made of epoxy resin or the like is formed The capacitor element 100 is fabricated by forming the anode body end portion 1c by removing the dielectric layer at both ends of the anode body extending further outward through 1b with a laser or the like.

  The size of the capacitor element 100 is, for example, a length of 15.0 mm, a width of 10.0 mm, a thickness of 0.25 mm, and made of a copper alloy or a nickel alloy, for example, a length of 8.0 mm, a width of 1.0 mm, An anode metal piece 4 having a thickness of 0.15 mm is connected to the anode body end 1c by welding or the like. As shown in FIG. 1B, the angle at which the anode body end 1c is bent in the direction of the anode external terminal 6 is 15 ° to about the surface facing the cathode external terminal 7 in the central region 1a of the anode body 1. 30 ° is desirable. When the angle is too small, a sufficient ESR reduction effect cannot be obtained, and when the angle is too large, the anode body 1 is likely to be cut.

  The anode body end portion 1c bent toward the anode external terminal 6 may be bent only on one side, not on both sides of the anode body end portion 1c, and may be determined in consideration of the configuration and manufacturing conditions of the solid electrolytic capacitor. Absent.

  The step of bending the anode end 1c can be performed in the step of mounting the capacitor element. The bending operation uses a jig provided with a step so as to bend the end of the anode body.

  Next, the configuration of the solid electrolytic capacitor in the embodiment of the present invention will be described.

  FIG. 1B is a diagram showing a solid electrolytic capacitor, in which the anode metal piece 4 and the anode external terminal 6 of the capacitor element 100 are electrically connected by the conductive adhesive 5, and the cathode layer 2 and the cathode of the capacitor element 100. The external terminal 7 is electrically connected by the conductive adhesive 5. As the conductive adhesive 5 to be used, an epoxy-based one containing a conductive filler such as copper or silver which is generally used may be used. The anode body 1 may be partially bonded to the conductive adhesive 5.

  At this time, since the anode body end 1c is bent in the direction of the anode external terminal 6, the adhesion area with the conductive adhesive 5 applied to the surface of the anode external terminal increases, and ESR can be reduced. Become. A plurality of capacitor elements 100 can be stacked, and the number of stacked layers may be increased depending on the target capacitance or ESR. The operation of bending the anode body end portion 1c in the case of stacking capacitor elements can also be performed in the stacking step.

  Finally, a resin lid 9 is put on the exterior resin case 8 to which the capacitor element 100 is connected and sealed with an adhesive 10 for the purpose of sealing, thereby obtaining the solid electrolytic capacitor 110 of the present invention.

  Examples of the present invention will be described with reference to the drawings used in the embodiment.

  FIG. 1A is a cross-sectional view illustrating a capacitor element used for a solid electrolytic capacitor, and FIG. 1B is a cross-sectional view illustrating a solid electrolytic capacitor.

  First, as shown in FIG. 1A, a dielectric layer is formed on the surface of an anode body 1 made of a valve-acting metal foil made of Al whose surface has been enlarged 200 times by etching treatment. A cathode layer 2 was formed by sequentially forming a solid electrolyte layer made of a conductive polymer layer, a graphite layer, and a silver paste layer in the central region 1a. Then, the dielectric layer is removed by laser at both ends of the anode body extending further outward through the resist forming portion 1b on which the resist layer 3 made of epoxy resin is formed, and the anode body end portion 1c is formed to form the capacitor element 100. Was made.

  Capacitor element 100 has a length of 14.8 mm, a width of 10.0 mm, a thickness of 0.25 mm, and an anode metal made of a copper alloy having a length of 8.0 mm, a width of 1.0 mm, and a thickness of 0.15 mm. The piece 4 is connected to the anode body end 1c.

  The angle at which the anode body end 1c is bent in the direction of the anode external terminal 6 is 15 ° with respect to the surface of the central region 1a of the anode body 1 facing the cathode external terminal 7 as a reference. The work of bending the anode body end 1c was performed by a jig in the capacitor element mounting process.

  Next, the configuration of the solid electrolytic capacitor will be described. FIG. 1B is a diagram showing a solid electrolytic capacitor. The anode metal piece 4 and the anode external terminal 6 of the capacitor element 100 are electrically connected by the conductive adhesive 5, and the cathode layer 2 and the cathode of the capacitor element 100 are connected. The external terminal 7 was electrically connected by the conductive adhesive 5. At this time, since the anode body end portion 1c is bent in the direction of the anode external terminal 6, the adhesion area with the conductive adhesive 5 on the anode external terminal 6 can be increased, and ESR can be reduced.

  Next, the outer resin case 8 to which the capacitor element 100 was connected was covered with a resin lid 9, adhered with an adhesive 10, and sealed to obtain a solid electrolytic capacitor 110. 50 samples were prepared.

Comparative example

  A solid electrolytic capacitor was fabricated under the same production conditions as in Example 1 except that the anode body end portion of the anode body was not bent toward the anode external terminal. 50 samples were produced.

  Table 1 shows the measurement results of the passage resistance values of the examples according to the present invention and the comparative examples. The passage resistance is a resistance value calculated from a voltage value when a constant current is passed through the two external anode terminals of the three-terminal solid electrolytic capacitor. It becomes an index of the connection resistance between the capacitor element and the external anode terminal, and the ESR is reduced by the decrease in the anode connection resistance. The applied current value was 10 A, and the number of measurements was 50 each.

  As is apparent from Table 1, in the examples, the average value of the passage resistance value is reduced by 15% compared with the comparative example, and the effect of the present invention is confirmed.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, various changes and modifications that can be naturally made by those skilled in the art are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Anode body 1a Center area | region 1b Resist formation part 1c Anode body edge part 2 Cathode layer 3 Resist layer 4 Anode metal piece 5 Conductive adhesive 6 Anode external terminal 7 Cathode external terminal 8 Exterior resin case 9 Lid 10 Adhesives 100, 200 Capacitor element 110, 210 Solid electrolytic capacitor

Claims (2)

  A plate-like or foil-like surface-enhanced valve metal is used as an anode body, an anode metal piece constituting the anode part is connected to an anode body end which is an end of the anode body, and at least a central region of the anode body A capacitor element having a cathode layer in which a dielectric layer made of an oxide film is formed on the surface of the dielectric layer, and a solid electrolyte layer, a graphite layer, and a silver paste layer are sequentially formed on the surface of the dielectric layer; A solid electrolytic capacitor comprising a terminal and a cathode external terminal, wherein the anode metal piece and the cathode layer are connected to the anode external terminal and the cathode external terminal via a conductive adhesive, and the end of the anode body is the A solid electrolytic capacitor characterized by being bent in the direction of the anode external terminal.   2. The solid electrolytic capacitor according to claim 1, wherein an angle at which the end of the anode body is bent toward the anode external terminal is 15 ° to 30 °.

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