JP2008187091A - Solid-state electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the ESL of a solid-state electrolytic capacitor, and to improve impedance characteristics in a high frequency region. <P>SOLUTION: The solid-state electrolytic capacitor has a plurality of adjacent capacitor elements 1 forming a cathode 7 by successively laminating a dielectric oxide film layer, a solid-state electrolytic layer and a cathode layer on the surface of the porous body of valve action metal powder to which an anode lead wire 3 is joined, and an anode terminal 8 connected to the anode lead wire 3 and a cathode terminal 9 connected to the cathode 7 are exposed to the mounting surface of an exterior resin 10. The anode lead wires 3 of the adjacent capacitor elements 1 are pulled out in opposite directions alternately and connected to a pair of anode terminals 8, respectively. The cathode 7 is connected to the cathode terminal 9 provided between the pair of anode terminals 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface mount solid electrolytic capacitor used in electronic equipment.

  Capacitors with excellent impedance characteristics are strongly demanded as electronic devices are increased in speed and frequency.

  FIG. 4 is a transparent perspective view of a conventional solid electrolytic capacitor.

  As shown in FIG. 4, the conventional solid electrolytic capacitor has an anode lead wire 33 made of a valve action metal embedded in a porous body obtained by sintering a valve action metal powder such as tantalum, niobium, titanium, or aluminum from one side. A dielectric oxide film is formed on the surface of the porous body.

  A solid electrolyte layer is formed on the surface of the dielectric oxide film, and a cathode layer 36 in which a carbon layer and a silver paste layer are sequentially formed is formed on the surface of the solid electrolyte layer, thereby forming the capacitor element 31. .

  Further, a plurality of capacitor elements 31 are arranged such that all the anode lead wires 33 are arranged on one side and the cathode layers 36 of the adjacent capacitor elements 31 are overlapped, and the anode lead wires 33 are connected to the anode terminal 38 formed of a lead frame. The cathode layer 36 is welded to a cathode terminal 39 made of a lead frame via a conductive adhesive. The anode terminal 38 and the cathode terminal 39 are drawn from the external resin portion 40 covering the capacitor element 31 to the mounting surface 41 to constitute a solid electrolytic capacitor.

  Thus, by providing a plurality of capacitor elements 31 and increasing the total surface area obtained by adding the surface areas of the outer peripheries of the porous bodies, the equivalent series resistance (ESR) of the solid electrolytic capacitor is reduced.

As such a conventional solid electrolytic capacitor, the one shown in Patent Document 1 is known.
Japanese Patent Laying-Open No. 2005-166832

  Such a conventional solid electrolytic capacitor can reduce impedance characteristics at a frequency of about 100 kHz, but it is difficult to improve impedance characteristics due to the effect of equivalent series inductance (ESL) in the high frequency region. There was a problem.

  An object of the present invention is to solve such a conventional problem and to provide a solid electrolytic capacitor that improves impedance characteristics in a high frequency region.

  In order to achieve the above object, the present invention forms a cathode part by sequentially laminating a dielectric oxide film layer, a solid electrolyte layer, and a cathode layer on the surface of a porous body of valve action metal powder to which an anode lead wire is bonded. A plurality of capacitor elements adjacent to each other, and a solid electrolytic capacitor in which an anode terminal connected to the anode lead wire and a cathode terminal connected to the cathode part are exposed on a mounting surface of an exterior resin part, the adjacent capacitor The anode lead wire of the element is pulled out in opposite directions and connected to the pair of anode terminals, and the cathode portion is connected to the cathode terminal provided between the pair of anode terminals. It is.

  As described above, according to the solid electrolytic capacitor of the present invention, a plurality of capacitor elements are drawn in directions in which the anode lead wires are alternately opposed to each other, and the cathode portions are overlapped and adjacent to each other, thereby charging and discharging the capacitor elements. Since the magnetic field generated when the current flows works to cancel the magnetic field of the adjacent capacitor element, the ESL of the solid electrolytic capacitor can be reduced, and the impedance characteristics can be improved in the high frequency region. It is what you play.

(Embodiment 1)
A solid electrolytic capacitor according to Embodiment 1 of the present invention will be described.

  FIG. 1 is a transparent perspective view showing the configuration of the solid electrolytic capacitor according to Embodiment 1 of the present invention, FIG. 2A is a sectional view showing the configuration of the capacitor element, and FIG. It is the A section expanded sectional view of a).

  As shown in FIG. 2, the capacitor element 1 includes a rod-shaped anode lead wire 3 made of a valve metal such as tantalum and embedded in a rectangular parallelepiped made of a valve metal powder such as tantalum so as to protrude from one end face of the rectangular parallelepiped. The green body is sintered to form a porous body 2, and a dielectric oxide film layer 4 is formed on the surface of the porous body 2 by electrolytic anodization.

  A solid electrolyte layer 5 made of at least one of a conductive polymer such as polypyrrole, polythiophene and polyaniline, an organic semiconductor such as TCNQ, and an inorganic semiconductor such as manganese dioxide is formed on the surface of the dielectric oxide film layer 4. Further, a cathode layer 6 in which a carbon layer containing graphite, a conductive paste layer made of silver particles, an epoxy resin, a phenol resin, and the like are sequentially formed on the surface of the solid electrolyte layer 5 on the outer peripheral surface of the porous body 2 is formed. A dielectric oxide film layer 4 is formed on the surface of the porous body 2, and a cathode portion 7 comprising a solid electrolyte layer 5 and a cathode layer 6 is formed on the surface of the dielectric oxide film layer 4. Element 1 is obtained.

  As shown in FIG. 1, the anode terminal 8 and the cathode terminal 9 are metal conductors made of copper, iron, nickel, alloys thereof, and the like, and are formed by cutting a block-shaped metal conductor. is there.

  The anode terminal 8 and the cathode terminal 9 may be a lead frame obtained by punching and bending a plate-like metal conductor.

  The anode terminal 8 has flat metal conductors 8a exposed at both ends of the bottom surface of the mounting surface 11, and the upper surface of the block spacer portion 8b provided on the upper part of the flat metal conductor 8a, and the anode lead The wire 3 is joined by resistance welding, laser welding, ultrasonic welding or the like.

  The flat metal conductor 8a and the spacer portion 8b may be formed by joining a single metal conductor, or may be integrally formed by cutting or the like from a single metal conductor.

  The cathode terminal 9 is obtained by joining the upper surface of a flat metal conductor 9a exposed between the pair of anode terminals 8 to the center of the bottom surface of the mounting surface 11 and the cathode portion 7 via a conductive adhesive. .

  The capacitor element 1 is arranged such that a plurality of capacitor elements 1 are parallel to the mounting surface 11 and adjacent to each other in the lateral direction, which is a direction perpendicular to the direction of the anode lead wire 3, and the anode lead wires 3 of the adjacent capacitor elements 1 are arranged. The cathode portions 7 of the adjacent capacitor elements 1 are pulled out in directions opposite to each other and connected to the pair of anode terminals 8, and the substantially entire side surfaces of the cathode portions 7 (adjacent surfaces of the capacitor elements) overlap each other. The cathode terminal 9 is connected to the surface (mounting direction surface) of the cathode portion 7 that is in contact with and intersects the overlapping surface.

  Moreover, the adjacent cathode part 7 may join what overlapped the cathode layer 6 surface with a conductive adhesive.

  Further, the connecting portion between the capacitor element 1 and the anode terminal 8 and the cathode terminal 9 and the capacitor element 1 are covered with an insulating exterior resin portion 10 made of epoxy resin, phenol resin or the like, and the anode terminal 8 and the cathode terminal 9 are covered. Is extended below the capacitor element 1 along the outer periphery of the exterior resin portion 10 or along the outer periphery of the exterior resin portion 10, and is exposed on the same surface as the bottom surface of the exterior resin portion 10 that becomes the mounting surface 11. is there.

  As described above, the current flowing through the valve metal of the porous body 2 of the capacitor element 1 and the current flowing through the valve metal of the porous body 2 of the capacitor element 1 adjacent to each other due to the capacitor element 1 being adjacent and conflicting with each other. Flow in the opposite directions and cancel the magnetic fields generated by the respective currents, so that the ESL of the solid electrolytic capacitor can be reduced.

  When resistance welding, ultrasonic welding, or the like in which the welding jig is brought into contact with the anode lead wire 3 is used, the adjacent distance between the anode lead wires 3 of the capacitor elements 1 arranged in one direction is such that all the capacitor elements 1 are connected. Compared to the one arranged in the same direction, it can be enlarged by one capacitor element 1 arranged in the other direction, so that the joint portion between the adjacent anode lead wire 3 and the anode terminal 8 is less deformed by welding. As a result, the assembly accuracy can be increased, the volume of the capacitor element 1 can be increased, the capacitance can be increased, and a large-capacity solid electrolytic capacitor can be obtained.

  In the first embodiment, the capacitor elements 1 are arranged in a lateral direction parallel to the mounting surface 11, but a plurality of capacitor elements 1 are sequentially stacked adjacent to each other in the vertical direction with respect to the mounting surface 11. The anode lead wires 3 of the capacitor element 1 to be drawn are alternately drawn in opposite directions and connected to the anode terminals 8 at both ends, respectively, and the cathode portion 7 of the adjacent capacitor element 1 is substantially the entire side surface of the cathode portion 7. May be connected to the cathode terminal 9 in contact with each other.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.

  FIG. 3 is a perspective view of the solid electrolytic capacitor according to Embodiment 2 of the present invention.

  In the second embodiment, a plurality of capacitor elements 1 are arranged adjacent to each other in the horizontal direction in parallel to the mounting surface 15, and the anode lead wires 3 of the adjacent capacitor elements 1 are drawn out in opposite directions, A pair of anode terminals 12 are connected to each other, and the side surfaces of the cathode portions 7 of the adjacent capacitor elements 1 are connected to the cathode terminals 13 by overlapping a part of the cathode lead 7 from the anode lead wire 3 side. In the second embodiment, two capacitor elements are arranged.

  That is, the plurality of capacitor elements 1 are arranged such that the cathode elements 7 of the capacitor elements 1 are shifted in the direction of the anode lead wires 3 so as to face the anode lead wires 3 of other adjacent capacitor elements 1. It is arranged.

  Further, the cathode portion 7 of the capacitor element 1 protrudes from the adjacent cathode portion 7 in the direction along the anode lead wire 3. The protruding cathode portion 7 is adjacent to a portion on the other anode terminal 12 side that is cut perpendicularly in the direction along the anode lead wire 3 so as to include the adjacent anode lead wire 3 or the other anode terminal 12. It is provided to extend from.

  The anode terminal 12 and the cathode terminal 13 use a lead frame formed by punching a flat metal conductor and bending it, and extend below the capacitor element 1 in the exterior resin portion 14. The anode terminal 12 is exposed to both ends of the mounting surface 15 of the exterior resin 14 and both side surfaces of the exterior resin portion 14 so as to be exposed to the same surface as the bottom surface. Are exposed on the center of the mounting surface 15 and on both side surfaces of the exterior resin portion 14.

  The pair of anode terminals 12 are arranged so as to be exposed from the end portion of the mounting surface 15 to the end surface of the exterior resin portion 14, and on the anode lead wire 3 side, a flat surface bent upwardly from the mounting surface 15. An upper portion 12b is formed, and the upper portion 12b and the anode lead wire 3 are joined using resistance welding, laser welding, ultrasonic welding, or the like.

  On the adjacent protruding cathode portion 7 side of the anode terminal 12 is bent upward, and the bent tip is electrically insulated from the protruding cathode portion 7 through the exterior resin portion 14. . Further, an insulating resin layer formed by sticking an insulating resin sheet or applying an insulating resin may be provided at the tip, and the anode terminal 12 and the protruding cathode portion 7 may be insulated.

  The cathode terminal 13 is disposed at the center between the pair of anode terminals 12. Further, a staircase pattern is formed so as to be exposed at both ends of the mounting surface 15 in a direction perpendicular to the mounting surface with respect to the direction connecting the pair of anode terminals 12 and further to be connected to the center upward from both ends. The upper portion 13b is bent to form a flat upper portion 13b, and the cathode portion 7 is bonded to the upper surface of the upper portion 13b with a conductive adhesive.

  Furthermore, the exterior resin portion 14 covers the capacitor element 1 and the connection portion between the capacitor element 1 and the anode terminal 12 and the cathode terminal 13.

  As described above, the ESL of the solid electrolytic capacitor can be reduced by making the capacitor elements 1 adjacent to each other and conflicting with each other. Further, by projecting the cathode part 7 of the capacitor element 1 in the direction along the anode lead 3 from the adjacent cathode part 7, the volume of the capacitor element 1 can be increased and the capacitance can be increased, and the low impedance and A large-capacity solid electrolytic capacitor can be obtained.

1 is a transparent perspective view of a solid electrolytic capacitor according to Embodiment 1 of the present invention. FIG. (A) Sectional drawing which shows the structure of the capacitor | condenser element of Embodiment 1 of this invention, (b) A section enlarged sectional view of the capacitor | condenser element Transmission perspective view of solid electrolytic capacitor in Embodiment 2 of the present invention Transmission perspective view of a conventional solid electrolytic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Porous body 3 Anode lead wire 4 Dielectric oxide film layer 5 Solid electrolyte layer 6 Cathode layer 7 Cathode part 8, 12 Anode terminal 9, 13 Cathode terminal 10, 14 Exterior resin part 11, 15 Mounting surface

Claims (2)

Provided with a plurality of adjacent capacitor elements in which a cathode portion is formed by sequentially laminating a dielectric oxide film layer, a solid electrolyte layer, and a cathode layer on the surface of a porous body of a valve action metal powder to which an anode lead wire is bonded, A solid electrolytic capacitor in which an anode terminal connected to the anode lead wire and a cathode terminal connected to the cathode portion are exposed on the mounting surface of the exterior resin portion, and the anode lead wires of adjacent capacitor elements are alternately opposed to each other. A solid electrolytic capacitor which is pulled out in a direction to be connected to the pair of anode terminals, and the cathode portion is connected to the cathode terminal provided between the pair of anode terminals. The solid electrolytic capacitor according to claim 1, wherein the cathode portion of the capacitor element is disposed so as to protrude from a cathode portion of another adjacent capacitor element in a direction along the anode lead wire.

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