JP4662365B2 - Surface mount capacitor - Google Patents

Description

  The present invention relates to a surface mount capacitor, and more particularly to a surface mount capacitor packaged with a case.

  FIG. 3 is a cross-sectional view of a conventional surface mount capacitor. The surface mount capacitor according to the prior art shown in FIG. 3 is called a three-terminal transmission line element. The conductive functional polymer layer 6 has an anode body 5 in which an anodized film is formed on an enlarged surface of a foil-like or plate-like valve action metal, and covers a central portion on the anode body 5. And a graphite layer 7 and a silver paste layer 8 are formed thereon to form a cathode portion 14. The anode terminal 3 is connected to the anode portions 13 at both ends of the anode body 5 separated by the insulating resin 12, and the cathode portion 14 and the cathode terminal 4 are connected via the conductive paste 9.

  Such a surface mount capacitor is described in Patent Document 1, and a technique of a multilayer surface mount capacitor in which capacitor elements are stacked is described in Patent Document 2.

JP 2004-55699 A JP 2004-289142 A

  Although the single-layer or multilayer surface-mount type capacitor is realized by the above-described conventional technology, further improvement in dimensional accuracy and high reliability are required depending on the application. In order to solve these problems, the present applicant in Japanese Patent Application No. 2004-311928 shuts off the capacitor element from the external environment, and in order to obtain a solid element container, the element is housed in a mold resin case, The structure which covers a part of upper part and a side wall with a box-type exterior case is proposed.

  FIG. 4 is a cross-sectional view of a surface mount capacitor obtained by improving the prior art. A conductive functional polymer layer 6, a graphite layer 7, and a silver paste layer 8 are sequentially formed in the central portion on the anode body 5 on which the anodized film is formed on the surface of the valve action metal to form a cathode portion 14. The cathode terminal 4 is arranged inside the mold resin case 2 in which the bottom surface portion is incorporated. The anode portions 13 at both ends of the anode body 5 are connected to the strip plate 10, and further connected to the anode terminal 3 via the conductive paste 9, and the cathode layer is connected to the cathode terminal 4 via the conductive paste 9. Thereafter, the outer case 1 was covered so as to cover the entire mold resin case 2 and fixed with an adhesive 11 to obtain a surface-mounted capacitor.

  In the surface mount type capacitor improved from the prior art, the mold resin case 2 and the outer case 1 are bonded and sealed with an adhesive 11 such as an epoxy resin. Therefore, in the reflow soldering at the time of mounting, depending on conditions, the internal pressure of the capacitor increases due to a rise in temperature, and a crack occurs on the bonding surface between the adhesive 11 of the mold resin case 2 and the outer case 1 with insufficient strength. Gas sometimes jetted, and the outer case 1 sometimes floated from the mold resin case 2.

  A technical problem of the present invention is to provide a highly reliable surface-mount thin capacitor that does not change its shape even when it receives heat or the like during reflow soldering during mounting.

  The surface mount thin capacitor of the present invention is a plate-like capacitor element having an anode part at the end and a cathode part at the center, or a capacitor element laminate formed by laminating capacitor elements, and connected to the anode part. In a surface-mounted capacitor comprising an anode terminal and a cathode terminal connected to the cathode portion, a mold resin case in which the anode terminal and the cathode terminal are incorporated in a bottom surface portion and a concave portion or a convex portion is provided outside the side surface portion; Covering the upper part and the side part of the mold resin case, and having an exterior case provided with a recess or a projection on the inside, the mold resin case and the exterior case are fitted with a gap part in part It is characterized by being.

  According to the present invention, the concave portion or the convex portion is provided outside the side surface portion of the mold resin case, the concave portion or the convex portion is provided inside the side surface portion of the outer case, and the mold resin case and the outer case have a gap in part. Because of this, the gas inside the surface mount capacitor escapes to the outside through the gap between the mold resin case and the exterior case even when the temperature rises during reflow soldering during mounting. It is possible to provide a surface mount type capacitor that does not increase and the outer case does not float from the molded resin case.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a surface mount capacitor according to a first embodiment of the present invention. A surface mount thin capacitor according to a first embodiment of the present invention will be described with reference to FIG. First, an anodic oxide film is formed on the surface of a flat valve action metal to form an anode body 5 of the valve action metal. The conductive functional polymer layer 6 is formed around the central portion of the anode body 5, the graphite layer 7 and the silver paste layer 8 are further formed as the cathode layer, and then the anode body 5 extending outside the anode body 5 is formed. The strip plate 10 is connected to the anode portions 13 at both ends to form a capacitor element.

  Next, the anode terminal 3 is disposed at both ends of the bottom surface portion, the cathode terminal 4 is disposed at the center of the bottom surface portion, and the box-shaped mold resin case 2a in which the anode terminal 3 and the cathode terminal 4 are integrally formed by injection molding or the like, The cathode layer of the capacitor element and the cathode terminal 4 are connected by the conductive paste 9, and the anode portion 13 and the anode terminal 3 are connected by the conductive paste 9 through the strip plate 10. Here, a recess is provided outside the side surface of the mold resin case 2a.

  Next, a box-shaped outer case 1a provided with a convex portion inside the side surface so as to partially fit with the concave portion of the mold resin case 2a is installed so as to cover the mold resin case 2a. At this time, the side portion of the mold resin case 2a and the side portion of the outer case 1a are configured to have a fitting portion 16 and a gap portion 15 in the fitting portion 16, and the mold resin case 2a is fitted to the fitting portion 16. In addition, the outer case 1a is fixed and a gap 15 is provided to provide a gas extraction path.

  FIG. 2 is a cross-sectional view of a surface mount capacitor according to the second embodiment of the present invention. The first embodiment of the present invention has a structure in which a concave portion and a convex portion are provided outside the side surface portion of the mold resin case 2b, and a convex portion and a concave portion are provided inside the side surface portion of the exterior case 1b. By providing the concave portion and the convex portion on the side surface portion, the contact area of the fitting portion 16 becomes larger than that in the first embodiment, and the fitting becomes stronger. In Embodiment 1 and Embodiment 2 of the present invention, the concave portion and the convex portion may be provided on two adjacent side surfaces, two opposing side surfaces, or three side surfaces and four side surfaces. Further, the gap portion 15 may be provided on a part of the side surface, and at least one gap portion may be provided.

  Although the embodiments of the present invention have been described above, although not described in the embodiments, it is possible to use a multilayer surface mount capacitor in which a plurality of capacitor elements are stacked, as well as a fitting portion and a gap portion. There are various types of deformation, such as providing an inclination or a curved shape. The present invention is not limited to this embodiment, and includes various changes such as design changes within a scope not departing from the gist of the present invention.

1 is a cross-sectional view of a surface mount capacitor according to a first embodiment of the present invention. Sectional drawing of the surface mount type capacitor by Embodiment 2 of this invention. Sectional drawing of the conventional surface mount type capacitor. Sectional drawing of the surface mount capacitor which improved the prior art.

Explanation of symbols

1, 1a, 1b Exterior case 2, 2a, 2b Molded resin case 3 Anode terminal 4 Cathode terminal 5 Anode body 6 Conductive functional polymer layer 7 Graphite layer 8 Silver paste layer 9 Conductive paste 10 Strip plate 11 Adhesive 12 Insulation Resin 13 Anode portion 14 Cathode portion 15 Gap portion 16 Fitting portion

Claims (1)

  A plate-like capacitor element having an anode part at the end and a cathode part at the center, or a capacitor element laminate formed by laminating the capacitor element, an anode terminal connected to the anode part, and a connection to the cathode part In the surface mount capacitor comprising the cathode terminal formed, the mold resin case in which the anode terminal and the cathode terminal are incorporated in the bottom surface portion and provided with the concave portion or the convex portion outside the side surface portion, and the upper and side surfaces of the mold resin case And an outer case provided with a concave or convex portion on the inside, and the mold resin case and the outer case are partially fitted with a concave portion and a convex portion with a gap. A surface mount capacitor.

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