JP6475417B2 - Solid electrolytic capacitor element, manufacturing method thereof, and solid electrolytic capacitor - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor element using a conductive polymer as a solid electrolyte, a method for manufacturing the same, and a solid electrolytic capacitor.

  A solid electrolytic capacitor using tantalum, aluminum or the like as a valve action metal has a large electrostatic capacity and excellent frequency characteristics, and is therefore widely used in electronic devices such as portable electronic terminals and personal computers.

  In recent years, as electronic devices have higher reliability and higher performance, there has been an increasing demand for reduction of leakage current related to solid electrolytic capacitors.

  As an example of a conventional solid electrolytic capacitor, there is a configuration disclosed in Patent Document 1. In the solid electrolytic capacitor of Patent Document 1, in order to separate the anode and the cathode, it is necessary to remove from the dielectric oxide film layer formed on the outer surface of the anode lead-out line to the solid electrolyte layer.

  When the layers from the dielectric oxide film layer formed on the outer surface of the anode lead-out line to the solid electrolyte layer are removed by laser irradiation, the removed end faces are formed on the same plane.

  Another example is the configuration disclosed in Patent Document 2. In the solid electrolytic capacitor of Patent Document 2, an insulating polymer film is provided on the surface of a dielectric layer, and a chemical oxidation polymerization conductive polymer film is formed on the surface. By forming an electrolytic oxidation polymerization conductive polymer film by bringing a conductor into contact with the chemical oxidation polymerization conductive polymer film, the anode lead is separated from the electrolytic oxidation polymerization conductive polymer film. .

JP 2005-129622 A JP-A-01-105523

  In the configuration disclosed in Patent Document 1, since the end surfaces from the dielectric oxide film layer to the solid electrolyte layer are formed in the same plane, the insulation distance between the anode lead-out line and the solid electrolyte layer is short, In some cases, leakage current increases and short circuit failure (short circuit failure) occurs.

  In addition, in the method disclosed in Patent Document 2, an electrooxidation polymerization conductive polymer film is formed by bringing a conductor into contact with each other. Therefore, when removing the contacted conductor, the nearby electrooxidation polymerization conductive polymer is removed. The film may peel off together with the conductor. When the dielectric layer is exposed on the surface due to peeling of the electrooxidation polymerization conductive polymer film, leakage current increases and short circuit failure occurs.

  Therefore, an object of the present invention is to provide a solid electrolytic capacitor element that secures an insulation distance between an anode lead and a solid electrolyte layer and suppresses short-circuit defects, a manufacturing method thereof, and a solid electrolytic capacitor.

  In order to solve the above-mentioned problems, the solid electrolytic capacitor element of the present invention comprises an anode body made of a porous body of valve action metal derived from the anode lead, a part of the anode lead, and a surface of the anode body. A dielectric layer formed; an insulating layer formed on at least a part of the dielectric layer formed on the surface of the anode lead; and at least a part of the dielectric layer and a part of the insulating layer. A solid electrolyte layer made of a conductive polymer is formed, and the surfaces of the insulating layer and the solid electrolyte layer are formed stepwise with respect to the surface of the anode lead.

  Here, by forming the surfaces of the insulating layer and the solid electrolyte layer stepwise with respect to the surface of the anode lead, only the portion where the anode lead is exposed and only the insulating layer formed on the surface of the dielectric layer are provided. It has an exposed portion and a portion where only the solid electrolyte layer formed on the surface of the insulating layer is exposed. The surface of the anode lead is formed by forming a stepped step composed of the surface of the anode lead, the surface of the insulating layer, and the surface of the solid electrolyte layer, and having an insulating layer exposed between the anode lead and the solid electrolyte layer. An insulating distance corresponding to the exposed insulating layer from the end of the insulating layer rising from the end to the end of the solid electrolyte layer rising from the surface of the insulating layer can be secured.

  In the solid electrolytic capacitor element of the present invention, it is desirable that at least a part of the surface of the anode lead has irregularities.

  The solid electrolyte layer of the solid electrolytic capacitor element of the present invention has at least a chemical polymerization layer formed by chemical polymerization, and the thickness of the chemical polymerization layer formed on the surface of the insulating layer is 1 μm or less (including 0). It is desirable that

  Further, in the solid electrolytic capacitor element of the present invention, the exposed distance of the insulating layer between the end of the insulating layer rising from the surface of the anode lead and the end of the solid electrolyte layer rising from the surface of the insulating layer Is preferably 10 μm or more and 15 μm or less.

  The solid electrolytic capacitor of the present invention includes the solid electrolytic capacitor element of the present invention, a cathode layer formed on the surface of the solid electrolyte layer, an anode terminal electrically connected to the anode lead, and the cathode layer, A cathode terminal electrically connected to the anode body and an exterior resin are provided, and the exterior resin covers a part of the anode terminal, a part of the cathode terminal, and the solid electrolytic capacitor element.

  In the method for manufacturing a solid electrolytic capacitor element of the present invention, the dielectric layer is formed on the surface of the anode body made of the porous body of the valve action metal derived from the anode lead, and the dielectric layer formed on the surface of the anode lead. An insulating layer is formed on at least a part of the surface, a solid electrolyte layer made of a conductive polymer is formed on the surface of the dielectric layer and the insulating layer, and a part of the dielectric layer formed on the anode lead In the laser processing that removes from the solid electrolyte layer to the solid electrolyte layer, the solid electrolyte layer in the vicinity to be removed peels from the insulating layer, and the surface of the insulating layer and the solid electrolyte layer is stepped with respect to the surface of the anode lead. It is characterized by forming.

  According to the present invention, in the laser processing for removing from the part of the dielectric layer formed on the anode lead to the solid electrolyte layer, the solid electrolyte layer in the vicinity to be removed is peeled off from the insulating layer and part of the insulating layer is removed. Is exposed on the surface. Thereby, a stepped step is formed on the surface of the insulating layer and the solid electrolyte layer with respect to the surface of the anode lead.

  As a result, a sufficient insulation distance corresponding to the length of the insulating layer exposed between the anode lead and the solid electrolyte layer is generated, so that contact between the anode lead and the solid electrolyte layer can be suppressed even during long-term use, resulting in a short circuit failure. Can be prevented.

  Also, in laser processing that insulates the anode lead from the solid electrolyte layer and removes the solid electrolyte layer from some of the dielectric layers formed on the anode lead so that the anode lead can be connected to the external anode terminal. Since a sufficient insulation distance between the anode lead and the solid electrolyte layer can be secured, there is no need to newly increase the number of manufacturing steps.

  From the above, it is possible to provide a solid electrolytic capacitor element that secures an insulation distance between the anode lead and the solid electrolyte layer and suppresses short-circuit defects, a manufacturing method thereof, and a solid electrolytic capacitor.

It is sectional drawing of the solid electrolytic capacitor element by this invention. FIG. 2A is an external view of the vicinity of the anode lead of the solid electrolytic capacitor element according to the present invention, FIG. 2A is an external view of the vicinity of the anode lead before laser processing, and FIG. 2B is an external view of the vicinity of the anode lead after laser processing. It is. It is sectional drawing which shows the structure of the solid electrolytic capacitor by this invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a cross-sectional view of a solid electrolytic capacitor element of the present invention. As shown in FIG. 1, the solid electrolytic capacitor element 10 of the present invention is formed of a sintered body made of metal fine particles having a valve action, a valve action metal that has been subjected to a surface expansion treatment to form a porous layer, and the like. An anode body 2 is provided, and an anode lead 1 is led out from the anode body 2.

  The valve action metal may be appropriately selected from tantalum, aluminum, titanium, niobium, zirconium, or alloys thereof.

  A dielectric layer 3 is formed on at least a part of the anode lead 1 and the surface of the anode body 2, and an insulating layer made of an insulating polymer is formed on at least a part of the surface of the dielectric layer 3 formed on the surface of the anode lead 1. 4 is formed. The insulating layer 4 may be formed by applying an epoxy resin, a silicon resin, or the like.

  The dielectric layer 3 is obtained by electrolytically oxidizing the surface of the valve action metal, and the thickness may be appropriately adjusted according to the voltage of electrolytic oxidation.

  A solid electrolyte layer made of a conductive polymer is formed on at least a part of the dielectric layer 3 and at least a part of the insulating layer 4. The solid electrolyte layer in this embodiment includes a chemical polymerization layer 5 made of a conductive polymer by chemical polymerization in which a monomer and an oxidant are reacted, and an electrolysis made of a conductive polymer by electrolytic polymerization that causes an electrochemical redox reaction. It is formed by the polymerization layer 6.

  Here, the solid electrolyte layer of the present embodiment is formed by combining the chemical polymerization layer 5 and the electrolytic polymerization layer 6, but may be formed only by the chemical polymerization layer 5.

  The thickness of the chemical polymerization layer 5 is desirably 1 μm or less (excluding 0). Thereby, the chemical polymerization layer 5 and the electrolytic polymerization layer 6 formed on the surface of the insulating layer 4 are easily peeled off from the insulating layer 4 at the time of laser processing described later.

  The chemical polymerization layer 5 may be a conductive polymer, and examples thereof include polythiophene, polypyrrole, and polyaniline. Similarly, the electropolymerization layer 6 may be formed by electropolymerization and may be a conductive polymer, and examples thereof include polythiophene and polypyrrole.

  After the formation of the solid electrolyte layer, the dielectric lead formed on the anode lead 1 in order to allow the anode lead 1 and the anode terminal to be connected when producing the solid electrolytic capacitor and further to insulate the anode lead 1 from the solid electrolyte layer. A part from the layer 3 to the solid electrolyte layer is removed by laser processing.

  At that time, the chemical polymerization layer 5 and the electrolytic polymerization layer 6 in the vicinity to be removed are peeled off from the insulating layer 4, and a part of the insulating layer 4 is exposed on the surface.

  Compared to the adhesion between the solid electrolyte layer and the dielectric layer, the adhesion between the solid electrolyte layer and the insulating layer is low. Therefore, a part from the dielectric layer formed in the vicinity of removing the anode lead to the solid electrolyte layer can be peeled off from the insulating layer by the impact of laser processing.

  As described above, the solid electrolyte layer is peeled off from the insulating layer 4 and a part of the insulating layer 4 is exposed, whereby the dielectric layer 3 on the surface of the anode lead 1, the chemical polymerization layer 5 which is a solid electrolyte layer, and the electrolytic polymerization. The end surfaces of the layer 6 are not coplanar, and a step is formed by the surface of the anode lead 1, the surface of the insulating layer 4, and the surface of the solid electrolyte layer. That is, the surfaces of the insulating layer and the solid electrolyte layer are formed stepwise with respect to the surface of the anode lead.

  By exposing a part of the insulating layer 4, the exposed insulating layer 4 minutes from the end of the insulating layer 4 rising from the surface of the anode lead 1 to the end of the solid electrolyte layer rising from the surface of the insulating layer 4 is sufficient. Since a long insulation distance occurs, contact between the anode lead 1 and the solid electrolyte layer can be suppressed even during long-term use, and short-circuit defects can be prevented.

  The insulating distance, which is the length of the exposed insulating layer 4, is preferably 10 μm or more because a short circuit failure between the anode lead 1 and the solid electrolyte layer can be further suppressed. In addition, the productivity is improved by the distance at which the solid electrolyte layer easily peels off, so that the insulation distance is desirably 15 μm or less. However, it is desirable that the insulation distance is as long as possible to suppress short circuit defects.

  When producing a solid electrolytic capacitor using a solid electrolytic capacitor element, the anode lead of the solid electrolytic capacitor element is connected to an anode terminal which is an external terminal. In the solid electrolytic capacitor element 10 of the present invention, the anode lead 1 and the solid electrolyte layer are peeled off by peeling off a part of the solid electrolyte layer during laser processing for connecting the anode lead 1 and the anode terminal which is an external terminal. Insulation can be secured. Therefore, the solid electrolytic capacitor element 10 of the present invention can be obtained without increasing the number of manufacturing steps.

  FIG. 2 is an external photograph of the vicinity of the anode lead of the solid electrolytic capacitor element according to the present invention, FIG. 2 (a) is an external photograph of the vicinity of the anode lead before laser processing, and FIG. 2 (b) is the vicinity of the anode lead after laser processing. It is an appearance photograph. FIG. 2A is an external photograph of the vicinity of the anode lead formed up to the insulating layer 4 on the surface of the anode lead 1 so that the surface state of the anode lead can be easily understood. FIG. 2 (b) is an external view of the vicinity of the anode lead subjected to laser processing after the chemical polymerization layer (not shown) and the electrolytic polymerization layer 6 are sequentially formed on the solid electrolytic capacitor element of FIG. 2 (a). is there. As can be seen from FIG. 2, irregularities are formed on the surface of a part of the anode lead subjected to laser processing by removing a part from the dielectric layer formed on the anode lead 1 to the solid electrolyte layer by laser processing. Is done.

  FIG. 3 is a cross-sectional view showing the configuration of the solid electrolytic capacitor of the present invention. As shown in FIG. 3, the solid electrolytic capacitor 300 of this embodiment includes a solid electrolytic capacitor element 10 according to the present invention, an anode terminal 7 and a cathode terminal 8 that are external electrodes, and an exterior resin 9.

  In the solid electrolytic capacitor element 10 used in the solid electrolytic capacitor 300 of the present embodiment, a cathode layer (not shown) is further formed on the surface of the electrolytic polymerization layer 6. The cathode layer is obtained, for example, by sequentially forming a graphite layer and a silver paste layer on the surface of the solid electrolyte layer.

  An anode terminal 7 as an external electrode terminal is electrically connected to the anode lead 1 by resistance welding or the like, and a cathode layer and the cathode terminal 8 as an external electrode terminal are electrically connected by a conductive adhesive (not shown) or the like. To do. The anode terminal 7 and the cathode terminal 8 are generally obtained by plating nickel or tin on a base material such as a copper plate.

  Thereafter, the solid electrolytic capacitor element 10, a part of the anode terminal 7 and a part of the cathode terminal 8 are covered with an exterior resin 9 made of an epoxy resin or the like, which is an insulating material, to obtain a solid electrolytic capacitor 300.

Example 1
Tantalum metal powder was used for the valve action metal constituting the anode body. An anode lead made of tantalum wire was embedded in tantalum metal powder, pressure-molded, and sintered to obtain an anode body. The obtained anode body and anode lead were immersed in an aqueous phosphoric acid solution to perform anodization, and a dielectric layer was formed on the surfaces of the anode body and anode lead. Next, an insulating layer was formed by applying silicon resin to a part of the surface of the dielectric layer formed on the surface of the anode lead.

  Thereafter, a conductive polymer made of poly3,4-ethylenedioxythiophene was formed as a solid electrolyte layer by chemical polymerization so as to cover the dielectric layer, the insulating layer, and a part of the surface of the anode lead. At this time, the thickness of the chemical polymerization layer formed on the surface of the insulating layer was 1 μm.

  Next, a part of the dielectric layer and the insulating layer formed on the tip side of the anode lead were removed by laser processing to expose the surface of the anode lead at the tip of the anode lead. Power was supplied from the exposed surface of the anode lead, and a conductive polymer made of polypyrrole was formed on the surface of the chemical polymerization layer by electrolytic polymerization.

  In order to allow insulation between the anode lead and the solid electrolyte layer, the solid electrolyte layer of the anode lead was removed by laser processing. At this time, laser processing was performed using a laser processing machine ML-7064A manufactured by Miyachi Technos, and the current value was set to 17.5 A and the frequency was set to 9 kHz.

  By this laser processing, the removed chemical polymerization layer and electrolytic polymerization layer in the vicinity were separated from the insulating layer, and the surface of the insulating layer was exposed. It was confirmed that the surface of the insulating layer and the solid electrolyte layer were formed stepwise with respect to the surface of the anode lead by exposing the surface of the insulating layer by laser processing. The insulation distance, which is the length of the exposed insulating layer, from the end of the insulating layer rising from the surface of the anode lead to the end of the solid electrolyte layer rising from the surface of the insulating layer was 10 μm.

  The obtained solid electrolytic capacitor element was dipped in a graphite paste and dried to form a graphite layer on the surface of the electrolytic polymerization layer. Next, after dipping in a silver paste and performing a drying treatment to form a silver paste layer, the anode lead and the anode terminal were connected by welding, and the silver paste layer and the cathode terminal were connected by a conductive adhesive.

  Finally, a solid electrolytic capacitor element, a part of the anode terminal and a part of the cathode terminal were covered with an epoxy resin to form an exterior resin to obtain a solid electrolytic capacitor.

(Comparative Example 1)
As in Example 1, an anode body having a dielectric layer formed on the surface was produced. Thereafter, a conductive polymer made of poly3,4-ethylenedioxythiophene was formed as a solid electrolyte layer by chemical polymerization so as to cover the surface of the dielectric layer.

  Next, a part of the dielectric layer formed on the tip side of the anode lead was removed by laser processing, so that the surface of the anode lead was exposed at the tip of the anode lead. Power was supplied from the exposed surface of the anode lead, and a conductive polymer made of polypyrrole was formed on the surface of the chemical polymerization layer by electrolytic polymerization.

  In order to allow the insulation between the anode lead and the solid electrolyte layer and the connection between the anode lead and the anode terminal, a part from the dielectric layer of the anode lead to the solid electrolyte layer was removed by laser processing. At this time, laser processing was performed under the same apparatus and conditions as in Example 1. By this laser processing, the end surfaces of the dielectric layer and the solid electrolyte layer on the surface of the anode lead were formed in the same plane.

  The obtained solid electrolytic capacitor element was dipped in a graphite paste and dried to form a graphite layer on the surface of the electrolytic polymerization layer. Next, after dipping in a silver paste and performing a drying treatment to form a silver paste layer, the anode lead and the anode terminal were connected by welding, and the silver paste layer and the cathode terminal were connected by a conductive adhesive.

  Finally, a solid electrolytic capacitor element, a part of the anode terminal and a part of the cathode terminal were covered with an epoxy resin to form an exterior resin to obtain a solid electrolytic capacitor.

  After preparing 100 samples of Example 1 and Comparative Example 1, respectively, a voltage of 10 V was applied in an atmosphere of a temperature of 85 ° C. and a humidity of 85% RH. A voltage was applied for 500 hours, and the number of shorts occurred was investigated. The results are shown in Table 1.

  As apparent from Table 1, no short circuit was observed in the solid electrolytic capacitor of Example 1 to which the present invention was applied, but eight short circuit defects occurred in the solid electrolytic capacitor of Comparative Example 1. From this, it can be understood that short-circuit defects are suppressed by forming the surfaces of the insulating layer and the solid electrolyte layer stepwise with respect to the surface of the anode lead.

  As described above, a solid electrolytic capacitor element that secures an insulation distance between the anode lead and the solid electrolyte layer and suppresses short-circuit defects, a manufacturing method thereof, and a solid electrolytic capacitor can be obtained.

  As mentioned above, although the Example of this invention was described, this invention is not limited above, The change and correction of a structure are possible in the range which does not deviate from the summary of this invention. That is, it is a matter of course that various modifications and corrections that can be made by those skilled in the art are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Anode lead 2 Anode body 3 Dielectric layer 4 Insulating layer 5 Chemical polymerization layer 6 Electrolytic polymerization layer 7 Anode terminal 8 Cathode terminal 9 Exterior resin 10 Solid electrolytic capacitor element 300 Solid electrolytic capacitor

Claims (1)

A dielectric layer is formed on the surface of the anode body made of a porous body of the valve action metal derived from the anode lead,
Forming an insulating layer on at least a portion of the surface of the dielectric layer formed on the surface of the anode lead;
Forming a solid electrolyte layer made of a conductive polymer on the surfaces of the dielectric layer and the insulating layer;
In the laser processing for removing a part of the dielectric layer , the insulating layer, and the solid electrolyte layer formed on the anode lead, the solid electrolyte layer in the vicinity to be removed peels from the insulating layer,
In the lead-out surface of the anode lead, a portion where only the anode lead is exposed, a portion where only the insulating layer formed on the surface of the dielectric layer is exposed, and the solid formed on the surface of the insulating layer Solid having a portion where only the electrolyte layer is exposed, and is formed in a staircase shape so that the positions of the end portions of the dielectric layer, the insulating layer, and the solid electrolyte layer are lowered in order toward the anode body. Manufacturing method of electrolytic capacitor element.

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