JP2011096746A - Surface-mounting thin capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-mounting thin capacitor having a large capacity. <P>SOLUTION: In the surface-mounting thin capacitor, a metal core 12 and a metal foil consisting of etched layers 13 for covering both the faces of the metal core 12 are used as a base material, resist layers 5 formed, at a boundary between anodes at both ends of the metal foil; and the etched layers 13, formed on a surface of a center of the metal foil, are formed separated from the etched layers 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a surface mount thin capacitor.

  This type of surface mount thin capacitor uses a metal foil such as an aluminum foil as a base material. The metal foil includes a metal core part and an etched layer that covers both surfaces of the metal core part. Due to the chemical conversion, the surface of the metal foil is covered with an oxide film.

  FIG. 2 is a cross-sectional view of a conventional surface mount thin capacitor. A method for manufacturing the surface mount thin capacitor 100 according to the prior art will be described with reference to FIG.

  Both end portions of the metal core portion 12 made of the valve metal are used as the anode portion 1c, and the cathode portion 1a is formed on the surface of the central portion. First, an oxide dielectric is formed on the surface of the anode body of the valve action metal foil made of the etched layer 13 formed by enlarging the valve action metal such as plate-like or foil-like aluminum and forming on both surfaces of the metal core portion 12 made of the valve action metal. A body layer is formed. After forming the oxide dielectric layer, a portion of the etched layer at the boundary between the anode portion 1c and the cathode portion 1a is removed. A resist layer 5 is formed on the portion from which the etched layer has been removed, and separated into an anode portion 1c and a cathode portion 1a. Next, the conductive polymer layer 2 is formed so as to cover the surface of the oxide dielectric layer of the anode body of the valve metal foil, and then the anode body of the valve metal foil is immersed in the electrolyte solution and voltage is applied. By doing so, re-chemical conversion is performed to repair defects in the oxide dielectric layer.

  Thereafter, a cathode layer of a graphite layer 3 and a silver paste layer 4 is sequentially formed on the conductive polymer layer 2 of the cathode portion 1a, and an oxide dielectric layer and a resist layer 5 on the surface of the anode portion 1c, a conductive polymer. After removing the layer 2 with a laser or the like, the anode conductive piece 6 is joined to the anode portion 1c to obtain a solid electrolytic capacitor element. Next, the flat plate-like anode terminal 7 and cathode terminal 8 are formed on the same plane as the substrate mounting surface, and have a bottom surface portion that fills the gap between the anode terminal 7 and the cathode terminal 8 and mechanically connects them. The anode terminal 7a exposed on the inside of the mold resin case 10 having a side wall substantially perpendicular to the plane and the cathode terminal 8a exposed on the inside are connected to the anode conductive piece 6 of the anode part of the capacitor element and the silver paste layer 4 of the cathode part. Are connected by a conductive paste 9 and the upper periphery of the mold resin case 10 is covered with a lid 11 to form a surface mount thin capacitor 100. Such a surface-mount thin capacitor technology is disclosed in Patent Document 1 and the like.

JP 2005-216929 A

  However, in the conventional technique, since the resist layer is in contact with the etched layer, the resist resin that forms the resist layer penetrates into the etched layer. For this reason, it is difficult to form a conductive polymer layer that is a solid electrolyte in the portion formed by permeation of the resist resin, leading to a reduction in capacitance. That is, an object of the present invention is to provide a large-capacity surface-mount thin capacitor.

  The present invention increases the capacitance by forming a resist layer for the purpose of separating the anode portion and the cathode portion and preventing the resist resin from penetrating into the etched layer as a structure that does not contact the etched layer. This is what we found. That is, according to the present invention, there is provided a surface mount thin capacitor using a metal foil comprising a metal core and an etched layer covering both surfaces of the metal core as a base material, wherein both ends of the metal foil are anodes. A cathode is formed on the surface of the central portion of the metal foil, the surface-mount thin capacitor has a resist layer formed by removing the etched layer at the boundary between the anode and the cathode; A conductive polymer layer formed by monomer polymerization inside and on the surface of the etched layer in the center of the metal foil, and the surface on which the cathode is formed on the surface of the conductive polymer layer In the mounted thin capacitor, a surface mounted thin capacitor can be obtained in which the resist layer is formed apart from the etched layer.

  According to the present invention, in a resist layer formed of a resist resin for the purpose of separating the anode and the cathode, the resist resin can be prevented from penetrating by having a structure for preventing contact with the etched layer, and the capacitance is increased. Alternatively, it is possible to provide a surface mount thin capacitor having improved capacitance change characteristics by a moisture resistance test.

1 is a cross-sectional view of a surface mount thin capacitor according to an embodiment of the present invention. Sectional drawing of the conventional surface mount thin capacitor.

  Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a metal foil made of a valve action metal such as Al, Ti, Ta, or Nb is used as a base material. For example, an etched layer is formed on both surfaces of a metal core 12 that has been enlarged by etching or the like using Al. The metal foil on which 13 is formed is subjected to chemical conversion treatment by an electrochemical method to form an oxide dielectric layer. After the oxide dielectric layer is formed, the etched layer 13 at the boundary between the anode at both ends and the cathode at the center is partially removed by laser processing or the like until the metal core is exposed. Thereafter, the resist layer 5 is formed by applying a resist resin such as an acrylic resin, an epoxy resin, a phenol resin, an ABS resin, or a silicon resin to the portion from which the etched layer has been removed by a screen printing method or the like using a method such as screen printing or ink jet printing. After being formed away from the etched layer 13, drying and curing are performed. The separation width is targeted to be 1/2 or more of the width of the resist layer 5, and if the viscosity of the resist resin is too low, it will sag and contact the etched layer after formation, so the viscosity is in the range of 270 ± 30 dPa · s. Is preferred. In the case of screen printing, the dimensions of the screen printing plate are taken into consideration so that the resist layer 5 does not contact the etched layer 13. Thereafter, the conductive polymer layer 2 is formed by polymerization of the monomer inside the central etched layer and on the oxide dielectric layer on the surface. After the formation of the conductive polymer layer 2, the oxide dielectric layer is repaired by re-forming. A cathode layer composed of a graphite layer 3 and a silver paste layer 4 is sequentially formed on the conductive polymer layer 2, and the etched layer of the anode portion 1c at both ends is removed by laser processing or the like, and then the metal core of the anode portion 1c. The anode conducting piece 6 is joined to the portion 12 to form a capacitor element. Next, the flat plate-like anode terminal 7 and cathode terminal 8 are formed on the same plane as the substrate mounting surface, and have a bottom surface portion that fills the gap between the anode terminal 7 and the cathode terminal 8 and mechanically connects them. The anode terminal 7a exposed on the inside of the mold resin case 10 having a side wall substantially perpendicular to the plane and the cathode terminal 8a exposed on the inside are connected to the anode conductive piece 6 of the anode part of the capacitor element and the silver paste layer 4 of the cathode part. Are connected by a conductive paste 9 and the upper periphery of the mold resin case 10 is covered with a lid 11 to form a surface-mount thin capacitor 100.

  Examples will be described in detail below with reference to FIG. 1 used in the description of the embodiment. The surface-mount thin capacitor used as a base material an aluminum metal foil composed of a metal core 12 made of aluminum and an etched layer 13 covering both surfaces of the metal core 12. Both end portions of the metal foil were used as the anode portion 1c, and the central portion of the metal foil was used as the cathode portion 1a.

  A portion of the etched layer at the boundary between the anode and the cathode is removed by laser processing to a width of 0.5 mm, and an epoxy resin whose viscosity is adjusted to 250 dPa · S is filled therein by screen printing, thereby resist layer 5 Formed. At that time, the width of the screen printing plate was set to 0.3 mm, and the resist layer 5 was not in contact with the etched layer 13 as shown in the ellipse of FIG. Thereafter, after the conductive polymer layer 2 is formed by polymerization of the monomer inside and on the surface of the etched layer 13 in the central portion of the aluminum foil, the graphite layer 3 and the silver paste are formed on the surface of the conductive polymer layer 2. After forming the cathode composed of the layer 4 and removing the etched layer of the anode portion 1c at both ends by laser processing, the anode conductive piece 6 was joined to the metal core portion 12 of the anode portion 1c to manufacture a capacitor element. After the capacitor element is manufactured, the flat plate-like anode terminal 7 and cathode terminal 8 are formed on the same plane as the substrate mounting surface, and fills the gap between the anode terminal 7 and the cathode terminal 8 and mechanically connects the bottom surface portion. The anode terminal 7a exposed inside the mold resin case 10 and the cathode terminal 8a exposed inside the mold resin case 10 having a side wall substantially perpendicular to the plane, and the anode conductive piece 6 of the anode part of the capacitor element and the cathode part The silver paste layer 4 was connected by the conductive paste 9, and the upper periphery of the mold resin case 10 was covered with the lid 11, thereby manufacturing 100 surface mount thin capacitors 100.

(Comparative example)
In the comparative example, as shown in FIG. 2, a part of the etched layer at the boundary between the anode and the cathode is removed by laser processing to a width of 0.5 mm, and an epoxy resin whose viscosity is adjusted to 250 dPa · S is screened there. The resist layer 5 was formed by filling by printing. At that time, the width of the screen printing plate was larger than the removed width of the etched layer, 0.8 mm, and the resist layer 5 was in contact with the etched layer 13 as shown in the ellipse of FIG. 100 surface mount thin capacitors 100 were manufactured in the same manner as in the previous example except that the resist layer 5 was in contact with the etched layer 13.

  Here, the surface mount thin capacitor manufactured in the example and the surface mount thin capacitor of the comparative example manufactured by the conventional method, the capacitance value of each 100 pieces, and the average value of the capacitance change rate in the moisture resistance test Table 1 shows the comparison. The measurement conditions for the electrostatic capacitance value were 120 Hz, DC 1.5 V, and the moisture resistance test conditions were 65 ° C., 95% RH, and 500 hours.

  From Table 1, it can be seen that in the comparison between the example and the comparative example, the example has a larger capacitance, and the capacitance change by the moisture resistance test is smaller. This indicates that, according to the present invention, the penetration of the resist resin into the etched layer was suppressed, so that a difference was found in the amount of conductive polymer formed in the etched layer.

DESCRIPTION OF SYMBOLS 1a Cathode part 1c Anode part 2 Conductive polymer layer 3 Graphite layer 4 Silver paste layer 5 Resist layer 6 Anode conduction piece 7 Anode terminal 7a Anode terminal exposed inside 8 Cathode terminal 8a Cathode terminal exposed inside 9 Conductive page Stroke 10 Mold resin case 11 Lid 12 Metal core 13 Etched layer 100 Surface mount thin capacitor

Claims (1)

  A surface mount thin capacitor using a metal foil composed of a metal core portion and an etched layer covering both surfaces of the metal core portion as a base material, wherein both end portions of the metal foil are used as anodes, A cathode is formed on the surface of the central portion, and the surface-mount thin capacitor is in a central portion of the metal foil and a resist layer formed by removing the etched layer at the boundary between the anode and the cathode A conductive polymer layer formed by polymerization of a monomer inside and on the surface of the etched layer, and the negative electrode formed on the surface of the conductive polymer layer. A surface mount thin capacitor characterized in that is formed apart from the etched layer.

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