JP4775103B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor having a solid electrolyte layer made of a conductive polymer and a method for manufacturing the same.

  Conventionally, as a solid electrolytic capacitor, a solid electrolyte layer is formed on an electrode foil made of a valve metal having an etching layer with an enlarged surface area, and a conductor layer made of a graphite layer and a silver paste layer is sequentially laminated. A multilayer solid electrolytic capacitor is known in which a capacitor element is configured, and the capacitor element is sealed in a single layer or stacked layers.

  In such a solid electrolytic capacitor, as shown in FIG. 3, the resist layer 2 is provided on the etching layer 13 of the electrode foil 1 and divided into an anode portion 11 and a cathode portion 12 on which the solid electrolyte layer 6 is formed. Then, the solid electrolyte layer 6 and the conductor layer 7 are sequentially formed on the dielectric oxide film provided by anodic oxidation on the surface of the cathode portion 12, and then the anode lead portion 5 is connected to the anode portion 11. Further, an anode terminal 8 and a cathode terminal 9 are connected to the anode lead portion 5 and the conductor layer 7, respectively, and the entire capacitor element is covered with the exterior resin 3 by molding.

  Here, when a conductive polymer is used as the solid electrolyte, a method of forming a conductive polymer by chemical oxidative polymerization is known. In the case of chemical oxidative polymerization, a conductive high polymer is formed on the dielectric oxide film. This is a method of forming a conductive polymer layer on a dielectric oxide film by discharging or applying a polymerizable monomer solution and an oxidant solution as molecules. In this application, the polymerizable monomer solution and the oxidizer solution are collectively referred to as a solid electrolyte material. At this time, if the electrode foil 1 provided with the etching layer 13 is not divided into the anode portion 11 and the cathode portion 12 by the resist layer 2, the solid electrolyte material reaches the anode portion 11 through the gap between the etching layers 13, A solid electrolyte layer may be formed, causing an insulation failure between the anode portion 11 and the cathode portion 12, or leading to dielectric breakdown.

  For the above reasons, the resist layer 2 is formed for the purpose of separating the anode portion 11 and the cathode portion 12. Such a resist layer 2 exposes an unetched portion (remaining core layer 14) of the electrode foil 1 by removing the etching layer serving as a boundary between the anode portion 11 and the cathode portion 12 in a groove shape, and this groove 17 It is formed by injecting a resist material and curing it.

The following patent documents are known as a solid electrolytic capacitor in which the resist layer 2 is formed.
JP 2000-243665 A JP 2005-216929 A

  Since such a resist material needs to reach the remaining core layer 14 of the electrode foil 1 and separate the anode portion 11 and the cathode portion 12, it is preferable to select a material having a relatively low viscosity. . However, as shown in FIG. 4, when the resist material is injected into the groove 17, the resist material penetrates into the gaps in the etching layer 13. In particular, when a resist material having a low viscosity is used, the penetration of the electrode foil 1 in the length direction becomes remarkable. Since the resist material that has penetrated into the cathode portion 12 covers the dielectric oxide film of the cathode portion 12, even if the solid electrolyte layer 6 is formed thereafter, the portion covered with the resist material is used as a capacitor. The electrostatic capacity cannot be obtained. Thus, when the resist material flows to the cathode portion 12 side, there is a possibility that a desired capacitance of the solid electrolytic capacitor cannot be obtained.

  The present invention solves the above-described conventional problems, and prevents the resist layer 2 from flowing out to the cathode portion 12 by a simple method, thereby preventing a decrease in the capacitance of the solid electrolytic capacitor. And it aims at providing the manufacturing method.

  In the invention according to claim 1 of this application, the etching layer formed on the surface of the valve action metal is provided with a resist layer for preventing permeation of the solid electrolyte, so that the anode part and the cathode part are separated. In the solid electrolytic capacitor in which a dielectric oxide film layer, a solid electrolyte layer, and a conductor layer are sequentially formed on the surface of the cathode portion, and external terminals are electrically connected to the anode portion and the conductor layer, respectively, The first groove is formed by removing or compressing the etching layer on the cathode portion side.

  The invention according to claim 2 of this application is characterized in that, in the solid electrolytic capacitor according to claim 1, a second groove for injecting a liquid resist material for forming a resist layer is provided.

  In the invention according to claim 3 of this application, the etching layer formed on the surface of the valve action metal is provided with a resist layer for preventing permeation of the solid electrolyte, so that the anode part and the cathode part are separated, and the resist layer is used for classification. In the method of manufacturing a solid electrolytic capacitor, a dielectric oxide film layer, a solid electrolyte layer, and a conductor layer are sequentially formed on the surface of the cathode portion, and external terminals are electrically connected to the anode portion and the conductor layer, respectively. A step of forming a first groove formed by removing or compressing the layer, a step of forming a resist layer at a predetermined position on the anode portion side of the first groove, and a dielectric oxide film by anodization of the cathode portion The method includes a step of forming a layer and a step of forming a solid electrolyte layer.

  The invention according to claim 4 of the present application is the method of manufacturing a solid electrolytic capacitor according to claim 3, wherein the second groove portion is provided on the anode portion side of the first groove, and the resist layer is formed in the second groove portion. Is formed.

  The invention according to claim 5 of this application is the method of manufacturing a solid electrolytic capacitor according to claim 4, wherein the second groove for injecting the liquid resist material forming the resist layer is the first groove. It is characterized by being formed at the same time.

  As described above, when the first groove formed by removing or compressing the etching layer is provided on the cathode portion side of the resist layer, even if the resist material penetrates into the gap of the etching layer and flows out, the cathode The resist material that has permeated the portion side oozes out to the inner wall surface of the first groove. Here, the resist material that has oozed out to the inner wall surface of the first groove acts to attract the resist material in the direction of the etching layer by the surface tension of the resist material itself. For this reason, the resist material becomes difficult to flow out into the first groove, and stops until the resist material is exposed on the inner wall surface of the first groove or the entire inner wall surface is lightly wetted by the resist material, and it flows out further. Can be prevented. Thus, since the resist material is prevented from flowing out to the cathode portion, the cathode portion is not covered with the resist material. In addition, the anode layer and the cathode portion are reliably separated by the resist layer. This prevents the solid electrolyte formed in the cathode part from coming into contact with the anode part and reliably prevents the anode part and the cathode part from being short-circuited.

  In addition to providing the second groove for injecting the resist material in addition to the first groove, the resist material can easily and surely reach the remaining core layer of the electrode foil, and the anode part and the cathode part can be separated. It can be made more reliable.

  According to the invention of claim 1 of this application, when the solid electrolyte layer 6 made of a conductive polymer is formed on the cathode portion 12, the resist layer 2 prevents the solid electrolyte from flowing out to the anode portion 11. The anode part and the cathode part are not short-circuited. Further, since the cathode portion 12 is not covered with the resist layer 2, a solid electrolytic capacitor that can contribute the surface area of the cathode portion 12 as the capacitance of the solid electrolytic capacitor can be obtained.

  According to the invention of claim 2 of this application, it is possible to reliably separate the anode portion 11 and the cathode portion 12 by the resist layer 2 and to reliably prevent short-circuiting between the anode portion 11 and the cathode portion 12. Can do.

  According to the invention of claim 3 of this application, when the solid electrolyte layer 6 made of a conductive polymer is formed on the cathode portion 12, the resist layer 2 prevents the solid electrolyte from flowing out to the anode portion 11. The anode part and the cathode part are not short-circuited. Furthermore, since the cathode portion 12 is not covered with the resist layer 2, a solid electrolytic capacitor capable of contributing the surface area of the cathode portion 12 as the capacitance of the solid electrolytic capacitor can be manufactured.

  According to the invention of claim 4 of this application, it is possible to reliably separate the anode portion 11 and the cathode portion 12 by the resist layer 2 and to reliably prevent a short circuit between the anode portion 11 and the cathode portion 12. Can do.

  According to the invention of claim 5 of this application, since the first groove 15 and the second groove 16 are formed simultaneously, the work efficiency is not deteriorated.

  FIG. 1 shows the structure of an aluminum solid electrolytic capacitor according to the present invention, and FIG. The aluminum solid electrolytic capacitor and the manufacturing method thereof according to the present invention will be described in detail below.

  In FIG. 1, an electrode foil 1 is obtained by expanding an aluminum foil by etching treatment, and has a structure in which both surfaces of the aluminum foil become porous etching layers 13 and have gaps inside. Further, the inside of the aluminum foil is not etched and an aluminum ingot is left, and this aluminum ingot becomes the remaining core layer 14.

  For example, the electrode foil 1 is an aluminum foil made of high-purity aluminum having a thickness of 120 μm, and an etching layer 13 having a thickness of 40 μm is applied from both sides. In this case, the thickness of the remaining core layer 14 is 40 μm.

  In the vicinity of the end of the electrode foil 1 in the longitudinal direction, a second groove 16 is formed near the end, and a first groove 15 is formed in parallel with the second groove 16. These two grooves are formed by mechanically cutting the etching layer 13 and exposing the remaining core layer 14. Alternatively, the etching layer 13 may be removed by irradiating a laser. Further, mechanical cutting and removal by laser irradiation may be combined.

  In addition to the removal of the etching layer 13, the second groove 16 and the second groove 16 can be formed by compressing the etching layer 13 from both sides and crushing the etching layer 13 in the porous portion so that there is no gap. The first groove 15 may be formed.

  As described above, the purpose of forming the second groove 16 and the first groove 15 is to eliminate the gap between the porous portions formed by etching, and also by removing the etching layer 13, The etching layer 13 may be crushed to eliminate the gap.

  Then, a resist material is injected into the second groove 16. As the resist material, a thermosetting resin such as an acrylic resin or an epoxy resin, or an ultraviolet curable resin can be used. As the resist material, when this resist material is injected, the resist material penetrates into the gap of the etching layer 13 from the side surface of the second groove 16. Among these, as shown in FIG. 2, the resist material that has permeated the cathode portion 12 side penetrates to the inner wall surface of the first groove 15. Here, the surface tension of the resist material itself exerts a force that attracts the resist material in the direction of the etching layer 13. For this reason, the resist material becomes difficult to flow out into the first groove 15, stops at the extent that the resist material is exposed on the inner wall surface of the first groove 15, and is prevented from flowing out further.

  In this state, the resist material is thermoset. The resist layer 2 is formed by thermosetting. By this resist layer 2, the electrode foil 1 is divided into an anode portion 11 in a narrow region near the end portion and a cathode portion 12 in a wide region at one end.

  Thus, the resist layer 2 is prevented from flowing out toward the cathode portion 12 by the first groove 15. For this reason, since the etching layer 13 of the cathode portion 12 is not covered with a resist material, the formation of the solid electrolyte layer 6 described later can contribute to the capacitance of the solid electrolytic capacitor. .

  Next, on the cathode portion 12, aluminum is anodized to form a dielectric oxide film layer made of aluminum oxide. Further, a solid electrolyte layer 6 is formed on the dielectric oxide film. The solid electrolyte layer 6 can be formed by a method in which a polymerizable monomer solution that is polymerized to become a conductive polymer and an oxidizing agent solution are sequentially applied to or discharged from the cathode portion 12.

  The solid electrolyte layer 6 is in contact with the dielectric oxide film and functions as a true cathode. For this reason, the larger the area where the solid electrolyte layer 6 is in contact with the dielectric oxide film, the greater the capacitance of the solid electrolytic capacitor. Therefore, it is desirable that the solid electrolyte material (polymerizable monomer solution and oxidant solution) has high permeability to the etching layer 13, and a solution having a relatively low viscosity is selected.

  When a solution having a relatively low viscosity is selected as the solid electrolyte material, after discharging, the solution penetrates into the etching layer 13 and diffuses inside the etching layer 13. Even in this case, the permeation of these solutions into the anode part 11 is suppressed by the resist layer 2, and a short circuit between the anode part 11 and the cathode part 12 can be prevented.

  As described above, thiophene, pyrrole or their derivatives can be suitably used as the polymerizable monomer used for forming the solid electrolyte layer 6. More specifically, examples of the thiophene derivative include 3,4-ethylenedioxythiophene (abbreviated as EDOT). When EDOT is used as the polymerizable monomer, it is preferable to use an EDOT solution impregnated in the capacitor element in which EDOT is dissolved in a volatile solvent so that its concentration is 25 to 32 wt%. Examples of the volatile solvent include hydrocarbons such as pentane, ethers such as tetrahydrofuran, esters such as ethyl formate, ketones such as acetone, alcohols such as methanol, nitrogen compounds such as acetonitrile, and the like. Of these, methanol, ethanol, acetone and the like are preferable.

  As the oxidizing agent, an aqueous solution of ferric paratoluenesulfonate, periodic acid or iodic acid dissolved in ethanol can be used, and the concentration of the oxidizing agent with respect to the solvent is preferably 45 to 55 wt%, and 50 to 55 wt%. More preferred. The higher the oxidant concentration in the solvent, the lower the ESR. As the oxidant solvent, the volatile solvent used in the monomer solution can be used, and ethanol is particularly preferable. Ethanol is suitable as the oxidant solvent because it is easy to evaporate due to its low vapor pressure and the remaining amount is small.

  The solid electrolyte layer 6 can also be formed by applying a dispersion in which conductive polymer powder is dispersed and drying the solvent (dispersion medium).

  Further, on the solid electrolyte layer 6 of the capacitor element, a graphite layer and a silver paste layer are sequentially formed to form a conductor layer 7 to obtain a capacitor element.

  An anode lead portion is connected to the anode portion. For example, the anode lead-out portion is joined by inserting a metal plate between the anode portions of the electrode foil 1 and performing laser welding by laser irradiation from the side surface or electric welding. This anode lead-out part is used to make the electrical connection between the anode part and the anode terminal described later easy and reliable.

  A plurality of capacitor elements formed as described above are stacked, and an anode terminal is connected to the anode lead-out means. On the other hand, a cathode terminal 9 is connected to the silver paste layer of the conductor layer 7.

  Next, the exterior resin 3 is molded so that a part of the anode terminal 8 and the cathode terminal 9 is exposed to the outside, and the exterior is applied to obtain a solid electrolytic capacitor.

Next, a second embodiment will be described.
FIG. 5 is an enlarged cross-sectional view of a main part of the second embodiment.

  In FIG. 5, an electrode foil 1 is obtained by expanding an aluminum foil by etching treatment, and has a structure in which both surfaces of the aluminum foil become porous etching layers 13 and have gaps inside. Further, the inside of the aluminum foil is not etched and an aluminum ingot is left, and this aluminum ingot becomes the remaining core layer 14.

  A first groove 15 is formed in the vicinity of the end of the electrode foil 1 in the longitudinal direction. Similar to the first embodiment, the first groove 15 is formed by mechanically cutting the etching layer 13 and exposing the remaining core layer 14.

  Then, a resist material is injected into a predetermined position on the anode portion side from the first groove 15. As the resist material, a thermosetting resin such as an acrylic resin or an epoxy resin is used. When this resist material is injected, the resist material penetrates into the gaps in the etching layer 13 and reaches the remaining core layer 14. Further, the resist material that has permeated the cathode portion 12 side penetrates to the inner wall surface of the first groove 15. Here, the surface tension of the resist material itself exerts a force that attracts the resist material in the direction of the etching layer 13. For this reason, the resist material becomes difficult to flow out into the first groove 15, stops at the extent that the resist material is exposed on the inner wall surface of the first groove 15, and is prevented from flowing out further.

  In this state, the resist material is cured. By curing, the resist layer 2 is formed. By this resist layer 2, the electrode foil 1 is divided into an anode portion 11 in a narrow region near the end portion and a cathode portion 12 in a wide region at one end.

  The resist layer 2 is formed by the process as described above, and thereafter, a solid electrolytic capacitor is manufactured as in the first embodiment.

It is sectional drawing which shows the internal structure of the solid electrolytic capacitor of this invention. It is sectional drawing which shows the principal part of the solid electrolytic capacitor of this invention. It is sectional drawing which shows the internal structure of the conventional solid electrolytic capacitor. It is sectional drawing explaining the flow of the resist material in the conventional solid electrolytic capacitor. It is sectional drawing which shows the principal part of the solid electrolytic capacitor of 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode foil 11 Anode part 12 Cathode part 13 Etching layer 14 Remaining core layer 15 1st groove | channel 16 2nd groove | channel 17 groove | channel 2 Resist layer 3 Exterior resin 5 Anode lead-out part 6 Solid electrolyte layer 7 Conductor layer 8 Anode terminal 9 Cathode terminal

Claims (5)

The etching layer formed on the surface of the valve metal is provided with a resist layer that prevents the solid electrolyte material from penetrating, so that the anode part and the cathode part are separated, and dielectric oxidation is performed on the surface of the cathode part separated by the resist layer. In a solid electrolytic capacitor in which a coating layer, a solid electrolyte layer, and a conductor layer are sequentially formed, and external terminals are electrically connected to the anode part and the conductor layer, the etching layer is removed or compressed on the cathode part side of the resist layer. A solid electrolytic capacitor having a first groove formed as described above. 2. The solid according to claim 1, further comprising a second groove formed by removing or compressing the etching layer closer to the anode portion than the first groove, and a resist layer is formed in the second groove. Electrolytic capacitor. The etching layer formed on the surface of the valve action metal is provided with a resist layer that prevents the penetration of the solid electrolyte, so that the anode part and the cathode part are separated, and the dielectric oxide film is formed on the surface of the cathode part separated by the resist layer. In the method of manufacturing a solid electrolytic capacitor in which a layer, a solid electrolyte layer, and a conductor layer are sequentially formed, and external terminals are electrically connected to the anode portion and the conductor layer, respectively, the first layer formed by removing or compressing the etching layer A step of forming a groove, a step of forming a resist layer at a predetermined position on the anode side of the first groove, a step of forming a dielectric oxide film layer by anodization of the cathode portion, and a solid electrolyte layer. A method of manufacturing a solid electrolytic capacitor including a forming step. 4. The solid according to claim 3, further comprising a second groove formed by removing or compressing the etching layer closer to the anode part than the first groove, and forming a resist layer in the second groove. Manufacturing method of electrolytic capacitor. The method for producing a solid electrolytic capacitor according to claim 4, wherein the first groove and the second groove are formed simultaneously.