JP2006024966A - Solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor capable of shortening the distance between the current paths between an anode and a cathode, and an external circuit board, and further reducing the ESL of a high-frequency region in the solid electrolyte capacitor comprising a capacitor element in which a dielectric coating layer and a cathode layer are successively formed on the surface of an anode body, cathode and anode terminals that are connected to the anode body and the cathode layer, respectively, and are mutually alienated along a first direction for arrangement, and a packaging resin for covering the capacitor element. <P>SOLUTION: The lower surface of the capacitor element is oppositely connected to the upper surface of the cathode terminal over a nearly entire region in which the cathode layer is formed for a first direction. The anode and cathode terminals have anode and cathode exposure sections exposed from the packaging resin on the bottom surface of the solid electrolytic capacitor each. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a solid electrolytic capacitor.

  Conventionally, a solid electrolytic capacitor having a structure shown in FIG. 6 is known.

  This solid electrolytic capacitor has a surface of an anode body 3 made of a sintered body of a valve action metal (tantalum, niobium, titanium, aluminum, etc.), and a dielectric coating layer 4 formed by oxidizing the surface of the anode body. Capacitor element 6 having a solid electrolyte layer 5a made of a conductive organic material such as a conductive inorganic material such as TCNQ complex salt or conductive polymer, and a cathode layer 5 in which a cathode lead layer 5b made of carbon, silver or the like is sequentially formed. The anode lead frame 11 is connected to the anode lead member 7 planted on one end surface of the anode body 3, the cathode lead frame 12 is connected to the cathode layer 5, and the epoxy is formed outside the capacitor element 6. Covered and sealed with an exterior resin layer 8 made of resin or the like, and the anode lead frame 11 and the cathode lead frame 12 are bent along the exterior resin 8 (example) Bas Patent Document 1).

  In the solid electrolytic capacitor having the above structure, since the upper and lower surfaces of the capacitor element need to be covered with an exterior resin, the ratio of the capacitor element cannot be sufficiently increased with respect to the external dimensions of the solid electrolytic capacitor finished product. There was a problem.

  Therefore, as shown in FIG. 7, the capacitor element 6 is mounted on a flat lead terminal, the gap between the capacitor element 6 and the exterior resin 8 is made as small as possible, and the outer dimensions of the finished solid electrolytic capacitor are as follows. A technique for incorporating a capacitor element 6 having a large occupied volume has been proposed (for example, Patent Document 2).

In the solid electrolytic capacitor described in Patent Document 2, since the lead terminal is in direct contact with the circuit board or the like, there is no need to bend the lead frame along the exterior resin as in the prior art. The electric circuit can be shortened, and ESR and ESL in a solid electrolytic capacitor finished product can be reduced.
Japanese Patent Laid-Open No. 10-64761 (FIG. 1) JP 2001-244145 A (2nd page, FIG. 1)

    The present invention provides a solid electrolytic capacitor that can shorten the distance between current paths of an anode, a cathode, and an external circuit board, and can further reduce ESL in a high-frequency region.

Among the present inventions, the invention according to claim 1 is a capacitor element in which a dielectric film layer and a cathode layer are sequentially formed on the surface of the anode body, and is connected to the anode body and the cathode layer, respectively, and in the first direction. A solid electrolytic capacitor comprising an anode terminal and a cathode terminal arranged apart from each other along, and an exterior resin covering the capacitor element,
The lower surface of the capacitor element is connected to the upper surface of the cathode terminal across substantially the entire region where the cathode layer is formed in the first direction,
The anode terminal and the cathode terminal have an anode exposed portion and a cathode exposed portion, respectively, exposed from the exterior resin on the bottom surface of the solid electrolytic capacitor.

  By using the present invention, the distance between the current paths of the anode and cathode and the external circuit board can be shortened, and the ESL in the high frequency region can be further reduced.

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

  (Embodiment 1) FIG. 1 is a longitudinal sectional view of a solid electrolytic capacitor in Embodiment 1. FIG. 2 is a longitudinal side view (a), a bottom view (b) and a lateral side view of the solid electrolytic capacitor in Embodiment 1. It is a figure (c).

  In this solid electrolytic capacitor, a dielectric oxide film 4 is formed on the surface of an anode body 3 made of a tantalum sintered body having an anode lead member 7 planted on one end face, a solid electrolyte layer 5a made of a conductive polymer, carbon And a cathode layer 5 in which a cathode lead layer 5b made of silver or the like is sequentially formed to produce a capacitor element 6, an anode terminal 1 is connected to the anode lead member 7, and a cathode terminal 2 is connected to the cathode layer 5. The outside of the capacitor element 6 is covered and sealed with an exterior resin 8 made of epoxy resin or the like. As a material for the anode terminal 1 and the cathode terminal 2, an alloy mainly composed of copper was used.

  The cathode terminal 2 is opposed to the anode exposed portion 1a and a first cathode exposed portion 20a exposed at a position near the anode exposed portion 1a where the anode terminal 1 is exposed on the bottom surface (lower surface) of the solid electrolytic capacitor. A second cathode exposed portion 20b exposed from the portion to be exposed. Between the first cathode exposed portion 20a and the second cathode exposed portion 20b, there is a cathode embedded portion 8a in which an exterior resin enters a recess provided in the cathode terminal 2 by sputtering or the like. The anode exposed portion 10 and the second cathode exposed portion 20b extend to the end of the anode lead member of the solid electrolytic capacitor in the planting direction (vertical direction), and the first cathode exposed portion 20a It has the extension part 21 extended to the edge part of the direction (lateral direction) orthogonal to the planting direction of an anode lead member on the basis of the lower surface of a solid electrolytic capacitor.

  A method for attaching a solid electrolytic capacitor according to the present invention will be described below with reference to the drawings.

  FIG. 5 is a process diagram for soldering the solid electrolytic capacitor according to the present invention to a circuit board. The circuit board 30 is provided with lands 40 at positions corresponding to the anode exposed portions 10 and the cathode exposed portions 20 of the solid electrolytic capacitor of the embodiment, and solder 50 is applied on the lands 40, and then the solid An electrolytic capacitor is placed and soldered by a reflow process.

By using the above means, in the step of placing the solid electrolytic capacitor on the solder, the difference in area between the anode exposed portion 10 and the cathode exposed portion 20 can be reduced, and the corresponding land Since the area ratio of 40 (difference in the amount of applied solder) can also be reduced, the displacement of the solid electrolytic capacitor can be suppressed, problems such as poor appearance can be eliminated, and good soldering can be performed.
(Embodiment 2) FIG. 3 is a longitudinal sectional view of a solid electrolytic capacitor in Embodiment 2, and FIG. 4 is a longitudinal side view (a), a bottom view (b), and a lateral side view of the solid electrolytic capacitor in Embodiment 2. c).

In this solid electrolytic capacitor, a capacitor element 6 is produced in the same manner as in Example 1, and the cathode exposed portion 20 is provided only at one position in the vicinity of the anode exposed portion 1a where the anode terminal 1 is exposed.
The ESL reduction effect is maximized by forming the cathode terminal 20 on the lower surface including the end portion of the capacitor element 6 closest to the anode terminal 1.

  Therefore, the ESL reduction effect similar to that of the solid electrolytic capacitor of Example 1 can be obtained for the solid electrolytic capacitor of Example 2. However, when the solid electrolytic capacitor is connected to the circuit board 30, the balance between the positions of the anode exposed part 10 and the cathode exposed part 20 is poor, so that the fixing strength is weakened, and the circuit board 30 is affected by external pressure or application. Therefore, the solid electrolytic capacitor can be easily removed.

  In comparison, the solid electrolytic capacitor of Example 1 can be fixed at three points of the anode exposed portion 10, the first cathode exposed portion 20a, and the second cathode exposed portion 20b, so that the solid electrolytic capacitor and the circuit board are fixed. Strength is improved. Therefore, good soldering can be performed while maintaining the ESL reduction effect previously proposed by the present applicant.

  In addition, since the extending portion 21 is provided, the first cathode exposed portion 20a is exposed from the lateral side surface of the solid electrolytic capacitor, and is soldered from the side surface after the soldering process is completed. Can be confirmed. The number and shape of the extending portions are not particularly limited, and may be one or plural, and may be provided only on one side or both sides of the first cathode exposed portion 21 as long as it is exposed from the side surface.

  As another embodiment of the present invention, as shown in FIG. 10, on the lower surface of the solid electrolytic capacitor, two cathode exposed portions 20 each having an extending portion 21 are provided in the lateral direction, and a cathode buried portion 8a is provided therebetween. , ESL reduction effect, connection strength improvement by three-point connection, and confirmation after completion of soldering can be performed.

  As another embodiment, as shown in FIG. 11, (a) the extended portion 21 is provided with the same width as the first cathode exposed portion 20a, and (b) the extended portion 21 of the first cathode exposed portion 20a is provided. The same effect can be obtained even if a structure such as (c) an extended portion provided between the first cathode exposed portions is provided on the two-cathode exposed portion 20b side.

  In this example, a tantalum sintered body was used as a material for the anode body, but there is no particular limitation as long as a valve metal is used, and a sintered body such as niobium, titanium, aluminum, or a foil is used. The same effect can be obtained.

It is a longitudinal cross-sectional view of the solid electrolytic capacitor in Example 1 of this invention. It is the vertical side view (a) of the solid electrolytic capacitor in Example 1 of this invention, a bottom view (b), and a side view (c). 6 is a longitudinal sectional view of a solid electrolytic capacitor in Example 2. FIG. It is the vertical side view (a), bottom view (b), and side view (c) of the solid electrolytic capacitor in Example 2. It is process drawing which connects the solid electrolytic capacitor of an Example to a circuit board. It is a longitudinal cross-sectional view of the conventional solid electrolytic capacitor. It is a longitudinal cross-sectional view of another conventional solid electrolytic capacitor. It is a longitudinal cross-sectional view of a solid electrolytic capacitor. It is process drawing which connects the solid electrolytic capacitor which the present applicant devised previously to a circuit board. It is a bottom view of the solid electrolytic capacitor of another Example. It is a bottom view of the solid electrolytic capacitor of other examples.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anode terminal 10 Anode exposed part 2 Cathode terminal 20 Cathode exposed part 20a 1st cathode exposed part 20b 2nd cathode exposed part 21 Extension part 4 Dielectric film layer 5 Cathode layer 5b Solid electrolyte layer 5c Cathode extraction layer 6 Capacitor element 7 Anode lead member 8 Exterior resin 8a Cathode embedded portion 11 Anode lead frame 12 Cathode electrode lead frame 30 Circuit board 40 Land 50 Solder

Claims (6)

Capacitor elements in which a dielectric film layer and a cathode layer are sequentially formed on the surface of the anode body, and anode terminals and cathode terminals connected to the anode body and the cathode layer, respectively, and spaced apart from each other along the first direction A solid electrolytic capacitor comprising an exterior resin covering the capacitor element,
The lower surface of the capacitor element is connected to the upper surface of the cathode terminal across substantially the entire region where the cathode layer is formed in the first direction,
The anode terminal and the cathode terminal have an anode exposed part and a cathode exposed part respectively exposed from the exterior resin on the bottom surface of the solid electrolytic capacitor. 2. The solid electrolytic capacitor according to claim 1, wherein the cathode exposed portion includes a first cathode exposed portion and a second cathode exposed portion disposed at positions separated from each other on the bottom surface. 3. The solid electrolytic capacitor according to claim 2, wherein an exterior resin is exposed at a position between the first cathode exposed portion and the second cathode exposed portion on the bottom surface. When the direction orthogonal to the first direction is the second direction, the cathode terminal has a cathode second direction end exposed portion exposed from the exterior resin on the end surface in the second direction of the solid electrolytic capacitor,
The cathode second direction end exposed portion is connected to the cathode exposed portion, and is disposed at a position away from the first direction end of the solid electrolytic capacitor on the end surface in the second direction of the solid electrolytic capacitor. The solid electrolytic capacitor according to claim 1, 2, or 3. 5. The solid electrolytic capacitor according to claim 4, wherein the cathode second direction end exposed portion is exposed from an exterior resin on one and the other end surfaces in the second direction of the solid electrolytic capacitor. 6. The cathode terminal has a cathode first direction end exposed portion exposed from the exterior resin on one end face in the first direction of the solid electrolytic capacitor;
The said anode terminal has an anode 1st direction end exposed part exposed from the exterior resin in the other end surface of the said 1st direction of this solid electrolytic capacitor, The 1, 2, 3, 4 or 5 characterized by the above-mentioned. Solid electrolytic capacitor.

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