JP4867667B2 - Solid electrolytic capacitor - Google Patents

Description

  The present invention relates to an electrolytic capacitor using a solid electrolyte.

  2. Description of the Related Art In recent years, with high performance and miniaturization of electronic equipment, a capacitor having a high withstand voltage and a small size has been demanded.

  FIG. 8 is a cutaway perspective view of a conventional solid electrolytic capacitor. In FIG. 8, the surface of an aluminum foil etched as an anode foil 21 is provided with a dielectric film, and the aluminum foil etched as a cathode foil 22 is used. The anode foil 21 has an anode lead 27 and a cathode foil 22. Are provided with a cathode lead 28, and a capacitor element 24 is formed by winding a separator 23 between the anode foil 21 and the cathode foil 22. The capacitor element 24 is provided with a solid electrolyte 25 as an electrolyte and accommodated in a case 29. The solid electrolytic capacitor is provided with a sealing body 30 for inserting the anode lead 27 and the cathode lead 28 and sealing the opening of the case 29. Is configured.

  When considering a high breakdown voltage as a solid electrolytic capacitor, an aluminum foil which is an inexpensive general-purpose material is preferable as an electrode to be used. When realizing miniaturization at the same time, it is necessary to narrow the width of the aluminum foil as an electrode.

  In general, this electrode has a wide etching foil (hereinafter referred to as chemical conversion foil) formed with a dielectric film cut to a desired width with a slitter, so that the aluminum base is exposed from the end face. . Therefore, a dielectric film is formed on the end face by aging treatment.

Patent Document 1 is known as prior art document information related to the invention of the present application.
Japanese Patent Application Laid-Open No. 07-240351

  As the electrode width is reduced for miniaturization, the ratio of the area of the end face to the apparent area of the electrode increases, and the adverse effect of the dielectric film on the end face formed by aging becomes prominent. That is, normally, the dielectric film formed by aging is not dense in comparison with the dielectric film of the chemical conversion foil formed before slitting, and as a solid electrolytic capacitor is reduced in size. There was a problem that the leakage current would increase.

  Therefore, an object of the present invention is to reduce leakage current while realizing miniaturization.

In order to achieve this object, the present invention winds a valve metal wire in a spiral shape, uses the wound one end as an anode portion, and establishes a spiral shape center between adjacent valve metals excluding the anode portion. An anode body having a connecting portion provided radially from the portion, a dielectric film provided on the surface of the anode body other than the anode part, a solid electrolyte provided on the surface of the dielectric film, and a surface of the solid electrolyte A capacitor element wound in a spiral shape made of a current collector provided on the substrate, a plurality of capacitor elements stacked to form a laminate, an anode terminal electrically connected to the anode portion of the laminate, and the capacitor and the cathode terminal which is a current collector electrically connected to the element is obtained by chromatic and exterior resin covering at least the laminate.

  According to the present invention, since there is no exposure of the metal element on the electrode end face by the slitter, it is not necessary to form a dielectric film on the exposed metal element by aging as in the prior art, and the leakage current caused by this dielectric film This has the effect of being able to suppress the increase of.

  In addition, since the conventional aging process can be omitted, the process can be simplified and the productivity can be improved.

  Hereinafter, a solid electrolytic capacitor of the present invention will be described with reference to an embodiment and drawings.

  1 is a cross-sectional view of the solid electrolytic capacitor in Embodiment 1, FIG. 2 is a perspective view of an anode body, and FIG. 3 is a cross-sectional view of the solid electrolytic capacitor.

  1 and 2, an aluminum wire etched as the anode body 1 is used and a dielectric film 2 formed on the surface thereof is wound in a spiral shape. The anode body 1 may be wound with a pre-etched aluminum wire or may be etched after being wound.

  Similarly, the formation of the dielectric film 2 may be performed after the dielectric film 2 is formed on the surface of the etched aluminum wire, or may be wound after the aluminum wire is wound, and then the dielectric film is formed. 2 may be formed.

  A solid electrolyte 3 is formed on the surface of the dielectric film 2. As the solid electrolyte 3, a conductive polymer such as polypyrrole, polyaniline, polythiophene or the like can be used alone or in combination. As a forming method, conventional techniques such as chemical polymerization and electrolytic polymerization can be used.

  A current collector 4 is provided on the surface of the solid electrolyte 3. As the current collector 4, a laminate of a carbon layer and a silver paste can be used. In this way, the cathode portion 9 composed of the solid electrolyte 3 and the current collector 4 is formed.

  The capacitor element 5 is formed by the above configuration. A plurality of capacitor elements 5 are stacked via the current collector 4 (three in the first embodiment) to form a stacked body 6. The number of stacked capacitor elements 5 can be set as appropriate. Further, the capacitor elements 5 may be laminated in directions in which the anode portions are opposed to each other as shown in FIG. 1, or may not be alternated as shown in FIG.

  The anode part of each capacitor element 5 of the laminate 6 is connected to a pair of anode terminals 7. For this connection, resistance welding, laser welding, silver adhesive, or the like can be used.

  Similarly, a cathode terminal 8 is provided in the cathode portion 9. The cathode terminal 8 is connected to the center of the lower surface of the laminate 6 with, for example, a silver adhesive. With such a configuration, a three-terminal capacitor can be easily manufactured. In order to improve mountability, the exposed surfaces of the anode terminal 7 and the cathode terminal 8 are each subjected to a treatment such as nickel plating or solder plating. Further, the anode terminal and the cathode terminal itself may be formed by plating.

  The laminated body 6, the anode terminal 7, and the cathode terminal 8 are covered with an exterior resin 10, and the anode terminal 7 and the cathode terminal 8 are exposed from the mounting surface of the solid electrolytic capacitor. Thus, by shortening the drawing distance of the anode terminal 7 and the cathode terminal 8, there is an effect in reducing ESL and ESR.

  The cathode terminal 8 may be connected through the central portion of the stacked body 6 in the stacking direction. That is, a space is provided in advance in the central portion of the anode body 1, and connection is made so as to penetrate not only the central portion of the lower surface of the laminate 6 but also the central portion of each capacitor element 5. Has the effect of ensuring reliability and improving reliability. In addition, the volume can be reduced as compared with the case where the cathode terminal 8 is provided on the outer peripheral surface of the laminate 6.

  The anode body 1 may be simply wound in a spiral shape as shown in FIG. 2, but at least an adjacent valve metal wire after winding as shown in FIG. 4 (a). You may provide the connection part 15 between these.

  FIG. 4A is a perspective view of the anode body 1, in which a connecting portion 15 is provided between adjacent valve metal wires. In this case, it is possible to suppress a decrease in capacity particularly in the high frequency region. That is, by providing the connecting portion 15, a plurality of current flow paths can be provided, which makes it easier to put in and out electrons as a capacitor in a high frequency region. As a result, it is possible to suppress a decrease in capacity in the high frequency region.

  As a method of providing the connecting portion 15, adjacent valve metal wires may be connected by resistance welding, laser welding, or the like, or a new valve metal wire is provided and adjacent via this new valve metal wire. The valve metal wires to be connected may be connected.

  In particular, from the viewpoint of suppressing a decrease in capacity in the high frequency region, it is desirable to provide a plurality of connecting portions radially from the spiral central portion. Moreover, what is necessary is just to provide several connection parts in the outer peripheral surface, when an anode body is only a coil shape.

  The step of providing the connecting portion 15 is desirably performed after the etching process. This is because the connecting portion 15 may be melted and removed from the anode body 1 by the etching process.

  Moreover, as shown in FIG.4 (b), even if it uses so that it may have two derivation | leading-out parts 18, it may use so that the bent part of the valve metal wire folded in half may become the center part of a spiral. Good. This shape and the connecting portion 15 can be used either alone or in combination, and when combined, the effect is further reduced in ESR and ESL.

  The solid electrolytic capacitor is a so-called three-terminal capacitor, but can be a four-terminal capacitor.

  FIG. 5 is a perspective view of the mounting surface of the solid electrolytic capacitor in the present embodiment, and FIG. 6 is a cross-sectional view taken along line AA.

  The difference between the four-terminal capacitor and the three-terminal capacitor is the shape of the cathode terminal 11. That is, the terminal surface is branched in the mounting surface direction so that the pair of cathode terminals 11 are exposed on the mounting surface substantially perpendicular to the direction connecting the pair of anode terminals 7 on the mounting surface. With such a configuration, ESL can be reduced.

  In the present embodiment, the anode terminal and the cathode terminal have a structure in which reduction of ESR and ESL is important, that is, a structure in which the terminal distance between the capacitor element and the mounting surface is made as short as possible. As shown in FIG. 3, the conventional structure can also be used. That is, the anode part of the laminate 6 is connected to the anode terminal 13 with a laser, the cathode part 9 is connected to the cathode terminal 14 via the silver adhesive 16, and the laminate 6 and the anode terminal 13 are covered with the exterior resin 10. Alternatively, a part of the cathode terminal 14 may be covered, and the exposed anode terminal 13 and cathode terminal 14 may be bent along the outer peripheral surface of the exterior resin 10 and arranged on the mounting surface.

  In addition, the laminated body 6 is a laminate of a plurality of capacitor elements 5, but is not limited to this, and the capacitor element 5 can be used as a single layer.

  In addition, each capacitor element 5 of the laminate 6 is laminated via the current collector 4, but may be laminated via the solid electrolyte 3. In that case, it is desirable to form the current collector 4 on the outermost peripheral surface of the laminate 6 in order to reduce the contact resistance when connecting to the cathode terminals 8, 11, 14.

  The present invention has a feature of using a wound metal valve wire as an anode body, and is particularly useful for various electronic devices that are small and require low leakage current characteristics.

Sectional drawing of the solid electrolytic capacitor in one embodiment of this invention Perspective view of the anode body Cross section of the same solid electrolytic capacitor (A), (b) is a perspective view of the same anode body, respectively The perspective view of the mounting surface of the solid electrolytic capacitor in one embodiment of this invention Sectional view Sectional view Cutaway perspective view of a conventional solid electrolytic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anode body 2 Dielectric film 3 Solid electrolyte 4 Current collector 5 Capacitor element 6 Laminate body 7, 13 Anode terminal 8, 14 Cathode terminal 9 Cathode part 10 Exterior resin 15 Connection part 16 Silver adhesive 18 Derived part

Claims (1)

An anode having a coil metal wire wound in a spiral shape, one end of the coil wound as an anode portion, and a connecting portion provided radially from the spiral central portion between adjacent valve metals excluding the anode portion A body, a dielectric film provided on the surface of the anode body other than the anode portion, a solid electrolyte provided on the surface of the dielectric film, and a current collector provided on the surface of the solid electrolyte. A plurality of the capacitor elements rotated, a plurality of the capacitor elements are laminated to form a laminate, and an anode terminal electrically connected to the anode portion of the laminate and the current collector of the capacitor element are electrically connected and the cathode terminal, the solid electrolytic capacitor possess the exterior resin covering at least the laminate.

Images