JP2007180328A - Stacked solid electrolytic capacitor and capacitor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stacked solid electrolytic capacitor excellent in a high-frequecy characteristic with an ESR and an ESL characteristic improved. <P>SOLUTION: The stacked solid electrolytic capacitor comprises a plurality of single plate capacitor elements with an anode part formed on one side of a valve action metal plate on a flat plate having a dielectric oxide film layer on its surface, and a cathode part formed on the other side of the valve action metal plate laminated so that the anode part faces each other centering around the cathode; and each electrode part respectively connected to an anode lead frame and a cathode lead frame. The single plate capacitor element with its lateral size (w) longer than the longitudinal size (l) is selected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor having a novel configuration.

  Conventionally, as a solid electrolytic capacitor, a valve action metal such as aluminum or tantalum is used as an anode, an oxide film layer formed on the anode is used as a dielectric, and a solid electrolyte layer is formed thereon to form a cathode. Many are used. Known solid electrolytes include manganese dioxide, a TCNQ complex, and a conductive polymer (see, for example, Patent Document 1).

  In recent years, electronic devices have become smaller and higher in frequency, and capacitors have been required to have low ESR and ESL in the high frequency region. Solid electrolysis using a conductive polymer with high conductivity as the solid electrolyte. Capacitors have been commercialized. Since this solid electrolytic capacitor has a feature that the ESR is lower than that of a solid electrolytic capacitor using manganese dioxide, it is widely used and various improvements have been made (for example, see Patent Document 2).

  In order to achieve this low ESR, a method of increasing the number of stacked capacitor elements in the form of a flat plate is effective (see, for example, Patent Document 2). The contribution to the conversion is not enough.

  In general, the above-mentioned multilayer solid electrolytic capacitor is formed by etching the valve-acting metal foil surface to form a porous body, and then forming an oxide film layer on the surface of the anode element and an oxide film layer on the anode element. Low profile and low ESR because a single plate capacitor element composed of the formed solid electrolyte layer, carbon layer, and silver layer is laminated by using a conductive adhesive. Can be expected.

In addition, the present applicant has developed a capacitor having a novel configuration in which a single-plate capacitor element is alternately laminated so that the anode part is opposed to the cathode part as the laminated structure of the multilayer solid electrolytic capacitor. A structure (hereinafter referred to as a multi-terminal structure) has been proposed in which a cathode part is branched into a plurality of parts to bring out a magnetic field canceling effect and lower the ESL (refer to Patent Document 3).
Japanese Patent No. 2996992 JP 2003-45753 A Japanese Patent Application No. 2005-308846

  The present invention further develops the above-mentioned development results and further improves the ESR / ESL characteristics in the high frequency region, and provides a multilayer solid electrolytic capacitor that is particularly excellent in high frequency characteristics.

In order to solve the above problems, the present invention provides a single plate capacitor element in which an anode part is formed on one side of a valve action metal plate on a flat plate having an oxide film layer serving as a dielectric on the surface, and a cathode part is formed on the other side. In a solid electrolytic capacitor in which a plurality of layers are laminated,
The lateral dimension (w) of the single plate capacitor element (the length along the direction in which the anode part and the cathode part are formed) is selected to be longer than the longitudinal dimension (l). The multilayer solid electrolytic capacitor is characterized in that the anode portions are alternately laminated with the cathode portion as a center.

  In addition, the central cathode part is joined to the cathode terminal member, the anode parts arranged on both sides of the cathode part are joined to anode terminal members provided separately on both sides, and the anode terminal members on both sides are joined to the cathode. The multilayer solid electrolytic capacitor has improved electrical characteristics by being electrically connected through a connecting member disposed in a lateral region of the terminal member.

  Furthermore, the present invention provides a capacitor module in which electrical characteristics in a high frequency region are further improved by connecting and mounting a plurality of ceramic capacitors (MLCC) between an anode terminal member and a cathode terminal member.

  By the above means, it is possible to reduce the ESR and the ESL of the multi-terminal multilayer solid electrolytic capacitor.

  In the multi-terminal multilayer solid electrolytic capacitor of the present invention, the shape of the single-plate capacitor element is selected to be horizontally long (w> l) with a short vertical dimension, so that the current flow path (cross-sectional area) is substantially widened and reduced. ESR can be achieved.

  As described above, the vertical and horizontal dimensional ratio of the single-plate capacitor element is opposite to the conventional one, and the effect of the new idea structure of stacking the anodes alternately facing each other is more effectively promoted. That is, since the distance between the plurality of anode portions arranged opposite to each other is shortened and the generation of a magnetic field can be further suppressed, a remarkable ESL reduction effect can be achieved.

  Furthermore, by combining MLCCs with excellent high frequency characteristics into a module, a capacitor module with improved high frequency characteristics can be provided.

1, 2, and 3 are views for explaining a basic configuration of a single plate capacitor element before lamination of the multilayer solid electrolytic capacitor of the present invention. FIG. 1 is a plan view of one single plate capacitor element C. 2 is an external perspective view, and FIG. 3 is a cross-sectional view showing a detailed configuration thereof.
In FIG. 3, 1 is an anode element made of a valve action metal such as aluminum and tantalum, and 2 is a layer constituting a dielectric by an oxide film layer of the valve metal. 3 is a solid electrolyte layer constituting the cathode part formed on the surface of this oxide film layer, and is a layer formed by chemical polymerization or electrolytic polymerization of an electrolyte containing a conductive polymer such as polyethylenedioxythiophene (PEDT). is there. 4 and 5 are cathode lead layers, 4 is a carbon layer, and 5 is a silver layer.
Reference numeral 6 denotes a layer constituting the anode part of the valve metal plate. The anode part 6 and the cathode parts 3, 4, 5 (the whole is indicated by R) are completely insulated and isolated by the insulating masking member 7. One single plate capacitor element C is formed.

  In the present invention, as shown in FIGS. 1 and 2, in the single plate capacitor element C, the length in the direction in which the anode portion 6, the masking layer 7, the carbon layer 4, and the silver layer 5 are sequentially formed is expressed as a longitudinal dimension (l). When the length in the direction perpendicular to this is taken as the horizontal dimension (w), the examples in FIGS. 1 and 2 are examples in which (w) = 15 mm and (l) = 10 mm.

Next, examples of the present invention and comparative examples will be described.
Example 1
Below, the example of the production method of the lamination type solid electrolytic capacitor applied to the Example at the time of using an aluminum thin plate as a valve metal is shown.
A long aluminum foil having a thickness of 0.1 mm whose surface is electrochemically roughened is anodized for about 60 minutes by applying a voltage of 10 V in an aqueous solution of ammonium adipate to become a dielectric on the surface. An oxide film layer is formed. The aluminum foil thus formed with the oxide film layer is cut into dimensions of width (w) 15 mm and length (l) 10 mm, and as shown in FIG. 3, masking of an insulating resin or the like at an appropriate position. It coat | covers so that the member 7 may be wound, and divides the area | region (anode part and cathode part) on either side.
After that, the end face portion where the valve metal is exposed by the cutting is subjected to anodization for about 30 minutes by applying a voltage of 7 V again in an aqueous solution of ammonium adipate to form an oxide film layer on the cut surface. Thereafter, the solid electrolyte layer 3, the carbon layer 4, and the silver layer 5 are sequentially provided on the right side of the masking portion 7 (the R portion in FIG. 3) to form a cathode portion.

Next, the structure of a laminated body constituted by laminating the single plate capacitor element C is shown.
FIG. 4 shows a basic configuration of the multilayer capacitor of Example 1 in which the four single-plate capacitor elements C1, C2, C3, and C4 manufactured by the above method are stacked. The anode portion is centered on the cathode portion. Are alternately laminated so as to face each other (indicated by 6 and 6 '), and the cathode portions R are electrically connected by a conductive adhesive. The reference numerals in the figure indicate the same members as those in FIG. In the following embodiments, a terminal member for connecting an anode and a cathode to an external circuit will be referred to as a lead frame. A dotted line 13 in the figure is shown as a reference diagram in the case of the third embodiment (FIG. 9) and is not the first embodiment.

FIG. 5 is a side cross-sectional view of a finished product of the multilayer solid electrolytic capacitor, in which the anode parts 6 and 6 ′ on both sides are joined to the anode lead frames 8 and 8 ′ by a method such as resistance welding, and the cathode part in the center. Rs are bonded to the cathode lead frame 9 via a conductive adhesive.
In addition, the anode part of each layer is separated by the thickness of one single plate element when laminated, but when joining to the lead frame, resistance welding is performed together, so the upper and lower anode parts are as shown in the figure Are slightly bent and completely conductively joined. These laminates are externally molded with the resin 10 except for only the connection surface of each lead frame with the external circuit. The finished product has a rated voltage of 2.5 V and a rated capacity of 2200 μF.

(Example 2)
In FIG. 6, the shape of the single plate capacitor element is horizontally long (w> l), and a plurality of anode lead frames 8 and 8 ′ (up and down in the figure) are arranged in both side areas (left and right areas in the figure) of the cathode portion R. This is an example of a multi-terminal multilayer solid electrolytic capacitor that is electrically connected at two locations by left and right connecting members 11, 11 ′. Reference numeral 12 denotes an extension portion for extracting the potential of the cathode lead frame 9. The anode lead frames 8 and 8 ′ are separated from each other so as not to come into contact with the extension portion 12. The extension portion 12 is provided between the separated anode frames. To pass. Reference numeral 14 denotes an insulating resin film applied to the contact surface between the extension portion 12 and the anode portions 6 and 6 'of the single-plate capacitor element disposed thereon in order to prevent a short circuit. However, the illustration of the exterior mold resin is omitted for the sake of explanation.

FIG. 7 is a perspective view showing the arrangement structure of the lead frame portion of the above embodiment. The anode lead frames 8, 8 ′ and the cathode lead frame 9 are arranged on the lowermost surface of the laminated body, and these lower surfaces are substantially flush with each other. It joins to each cathode and anode so that it may become.
Note that FIG. 7 is a diagram at the stage of lamination, and shows a state before the upper and lower anodes are joined to each other by resistance welding or the like. Moreover, the code | symbol of a figure shows the same part as FIG.
FIG. 8 is a plan view showing the shapes of the cathode lead frame and the anode lead frame in the above embodiment, and the reference numerals in the figure are the same as those in each embodiment.

(Example 3)
FIG. 9 shows a multilayer solid electrolytic capacitor similar to that of Example 2, in which ceramic capacitors 13 and 13 ′ are connected between the connecting members 11 and 11 ′ connecting the anode lead frames and the cathode lead frame 9. FIG. 2 is a diagram showing the configuration of the composite capacitor, and the terminals of each ceramic capacitor are connected to an anode lead frame and a cathode lead frame, respectively.
In this example, a chip-type multilayer ceramic capacitor (MLCC) with a rated voltage of 6.3 V and a rated capacity of 1 μF is connected to each of the left and right sides of the cathode frame, and a composite multilayer capacitor with a total of 8 built-in ceramic capacitors. It is an example of a module.

(Modification)
FIG. 10 shows an example of a composite capacitor module which is a modified example of FIG. 9. An extension member 11 ″ is projected from the end of the anode lead frame 8 in a direction perpendicular to the extension member 11 ″ and the cathode lead frame 9. In this example, four ceramic capacitors (MLCC) 13 are connected in parallel. The example in the figure is an example in the case of one capacitor element plate, and the lead frame portion can have the same configuration even when a plurality of capacitor element plates are stacked. Although the extension member is provided on the anode lead frame in the figure, the extension member may be provided on the cathode lead frame so as to protrude toward the anode lead frame, or the extension member is protruded from both lead frames, and the MLCC is interposed therebetween. The effect is the same even if connected. In either case, the whole is molded with the MLCC connected and mounted between the cathode and anode lead frames to complete one capacitor module. Of course, the extending member and the connecting member may be made of a conductive member made of a material different from that of the lead frame.

(Comparative example)
FIG. 11 is a comparative example produced for comparison of electrical characteristics with the embodiment of the present invention, and a single plate capacitor element having a vertically long shape (w <l) having a width of 10 mm and a length of 15 mm is used. The same production as in Example 1 except that the anode parts 6 and 6 'are alternately arranged and stacked as in the above example, and the anode lead frames are independent from each other without being connected to each other. It was produced by the method.

  Table 1 is a comparison table of electrical characteristics of Examples 1 to 3 and the comparative example, and shows the results of actual measurement of ESR (mΩ) and ESL (pH) for each example. The ESR was measured at 100 kHz, and the ESL was measured at 100 MHz.

  As is clear from Table 1, the ESR and ESL values of the multilayer solid electrolytic capacitors of Examples 1 to 3 were greatly reduced as compared with the multilayer solid electrolytic capacitor of the comparative example. That is, it was demonstrated that the present invention can provide a multilayer solid electrolytic capacitor having lower ESR and ESL with the same rated voltage capacity.

  As described above, in Examples 1 to 3, the ESR can be reduced by making the shape of the single-plate capacitor element horizontally long (w> l), thereby substantially widening the current flow path (cross-sectional area). This is due to the fact that the ESL can be reduced because the shape of the capacitor element is a horizontally long shape (w> l), the distance between the opposing anode lead frames is shortened, and a magnetic field is generated. It is thought that it was greatly suppressed.

  Further, in Example 3, the ESL was able to be remarkably reduced due to the effect of mounting the MLCC having excellent high frequency characteristics in parallel on the anode lead frame and cathode lead frame common to the multilayer capacitor element.

  Furthermore, in this embodiment, a lead frame is used as a terminal member connected to an external circuit, but an insulating substrate provided with a through hole or a conductive layer serving as an external terminal may be used.

  Moreover, although the conductive polymer was used as the solid electrolyte in the examples, the same effect can be obtained by using manganese dioxide.

  In the above embodiment, the case where aluminum is used as the valve metal has been described. However, the same effect can be obtained by using tantalum, niobium foil, or a sintered body thereof.

  In each of the examples, the example of the lamination of four single-plate capacitor elements has been described. However, the same effect can be obtained even if the number of laminations is changed, and the example has been described for a three-terminal structure. Naturally, the same effect can be obtained even if the number of terminals is increased.

  In the embodiment, eight MLCCs having a rated voltage of 6.3 V and a rated capacity of 1 μF are used. However, the present invention is not limited to this, and the same effect can be obtained by changing the rating, number, mounting position, and the like.

  Furthermore, in the embodiment, the example in which two connecting members for electrically connecting the anode lead frames on both sides are provided on both sides of the cathode portion, but the connecting members may be connected only on one side, In this case, the ceramic capacitor is mounted only on one side.

The top view which shows the shape of the single-plate capacitor | condenser element used for this invention 1 is a perspective view of the single-plate capacitor element of FIG. Enlarged sectional view of a single plate capacitor element used in the present invention The perspective view which shows schematic structure of Example 1 which laminated | stacked four single plate capacitor | condenser elements of FIG. Side sectional view of the finished product of Example 1 The perspective view seen from the upper surface of the multilayer solid electrolytic capacitor of Example 2 The perspective view which shows schematic structure of the laminated body of FIG. Plan view showing the shape of the lead frame of each implementation The perspective view seen from the upper surface of the composite capacitor module of Example 3 Plane perspective view showing a modification of a capacitor module in which four MLCCs are connected and mounted A perspective view seen from the top of the multilayer solid electrolytic capacitor of the comparative example

Explanation of symbols

C1, C2, C3, C4, single plate capacitor element 1 valve action metal thin plate 2 oxide film layer 3 solid electrolyte layer 4 carbon layer 5 silver layer 6, 6 'anode portion 7 of capacitor element masking layer 8, 8' anode lead frame 9 Cathode lead frame 10 Resin mold 11, 11 ′ Anode lead frame connecting member 11 ″ Anode lead frame extension member 12 Cathode lead frame potential extraction extension 13 Ceramic capacitor 14 Insulating resin

Claims (4)

A solid electrolytic capacitor in which a plurality of single plate capacitor elements each having an anode portion formed on one side and a cathode portion formed on the other side of a valve metal plate having an oxide film layer serving as a dielectric on the surface thereof are laminated. The lateral dimension (w) of the single plate capacitor element is made longer than the longitudinal dimension (l) (the length along the direction in which the anode part and the cathode part are formed), and the anode parts are staggered around the cathode part. A laminated solid electrolytic capacitor, characterized in that the laminated solid electrolytic capacitor is laminated so as to face the capacitor.   In the above configuration, the central cathode part is joined to the cathode terminal member, and the anode parts arranged on both sides of the cathode part are joined to the anode terminal members respectively provided on both sides, and the anode terminal members on both sides are joined together. The multilayer solid electrolytic capacitor according to claim 1, wherein the multilayer solid electrolytic capacitor is electrically connected through a connecting member disposed in a lateral region of the cathode terminal member.   The cathode part of the capacitor element plate in which the cathode part is formed in the central part of the flat valve action metal plate having the oxide film layer serving as a dielectric on the surface and the anode part is formed on one side or both sides thereof, In the capacitor formed by bonding the anode part to the anode terminal member, a conductive extension member is provided on one or both of the cathode terminal member and the anode terminal member, and a plurality of the cathode terminal and the anode terminal member are interposed between the extension members. Capacitor module characterized by connecting a ceramic capacitor.   A plurality of capacitor element plates each having a cathode portion at the center and an anode portion on one side of a flat valve metal plate having an oxide film layer serving as a dielectric on the surface. The anode portion is centered on the cathode portion. In a multilayer capacitor formed by stacking layers so as to be opposed to each other and bonding each cathode part to a cathode terminal member and anode parts on both sides separately provided on both sides, the anode terminal members on both sides are cathodes A multilayer capacitor module comprising a plurality of ceramic capacitors connected electrically through a connecting member disposed in a lateral region of the terminal member, and a plurality of ceramic capacitors connected between the connecting member and the cathode terminal member. .