Capacitance device

Abstract

To provide a capacitance device formed by connecting a plurality of capacitance elements is conductively connected in parallel, capable of improving a request performance while miniaturizing a product.SOLUTION: A capacitance device 1 of the present invention, includes: a plurality of capacitance elements 2 that has a pair of electrodes 21 and 25; and a pair of electrode connection terminals 3 and 4 that has internal connection parts 31 and 41 that are conductively connected to one and the other one of the pair of electrodes. At least one of the electrodes 21 and 25 of the pair of electrodes in the plurality of capacitance elements 2 is corresponded to at least one of the electrodes 21 and 25, and is arranged so as to surround the internal connection parts 31 and 41 of at least one electrode connection terminals of the pair of electrode connection terminals, and is conductively connected in the status.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a capacitor device and other capacitance devices.

Background Art

[0002] In recent years, in capacitance devices used in in-vehicle products, industrial equipment, etc., low resistance, high ripple, and high capacitance have been required. In particular, in applications where high ripple characteristics are required, in order to avoid a reduction in product life due to internal heat generation by the ripple current, a conductive polymer solid electrolytic capacitor that uses a conductive polymer as an electrolyte has become mainstream for the purpose of reducing the ESR (equivalent series resistance).

[0003] In particular, even for a conductive polymer solid electrolytic capacitor, in order to cope with a high-frequency circuit, further reduction of ESR and ESL (equivalent series inductance) is important. For this reason, a capacitor device having a structure in which a plurality of capacitor elements are connected in parallel is used.

[0004] For example, in Patent Document 1 shown below, a plurality of capacitor elements in which an anodic oxide film layer, a solid electrolyte phase, and a cathode conductive layer are sequentially formed on an anode body made of a valve action metal are laminated, and a chip-type laminated solid electrolytic capacitor device that is molded and externally packaged with an insulating resin is described. In this capacitor device, a plurality of capacitor elements are configured to be joined to the tip of a cathode lead frame having a cross-sectional comb shape at one tip.

[0005] Furthermore, in Patent Document 2, multiple flat capacitor elements, each having a conductive polymer layer, a carbon paint layer, and a silver paint layer, are stacked and connected to terminal components by laser welding or the like. In addition, in Patent Document 3, multiple capacitor units constitute a rod-shaped capacitor element in which polymer fibers 110, a first conductive thin film layer 120, a dielectric thin film layer 130, and a second conductive thin film layer 140 are coaxially stacked, and with these rod-shaped capacitor elements stacked vertically and horizontally, the anode of each element is conductively connected to a first external connection electrode 20, and the cathode of each element is conductively connected to a second external connection electrode 30. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-274003 [Patent Document 2] Japanese Patent Publication No. 2005-236171 [Patent Document 3] Japanese Patent Publication No. 2010-21168 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] By the way, the capacitor devices disclosed in the above-mentioned conventional patent documents aim to increase capacitance and reduce ESR by stacking multiple capacitor elements. However, even so, increasing the number of stacked elements increases the size of the product, and in particular, the increased height hinders the miniaturization of electronic products. Furthermore, it increases the ESL, which increases the impedance in the high-frequency range.

[0008] Furthermore, increasing the number of stacked capacitor elements increases the number of conductive connection points within the product between the capacitor elements and lead terminals, which hinders miniaturization and may lead to an increase in ESL (Electronic Stability Limit), as well as increased manufacturing costs and reduced electrical reliability, among other problems caused by the internal conductive connection structure.

[0009] Therefore, the present invention solves the above problem, and its objective is to reduce the size of the product and improve the required performance in a capacitance device in which multiple capacitance elements are electrically connected in parallel, by reducing ESR, reducing ESL, and optimizing the internal conductive connection structure. [Means for solving the problem]

[0010] To solve the above problems, the capacitance device according to the present invention comprises a plurality of capacitance elements each having a pair of electrodes, and a pair of electrode connection terminals each having an internal connection portion electrically connected to one and the other of the pair of electrodes in the plurality of capacitance elements and an external connection portion electrically connected to the outside, wherein the plurality of capacitance elements are connected in parallel by the pair of electrode connection terminals, and is characterized in that at least one of the pair of electrodes in the plurality of capacitance elements is electrically connected in such a state that it surrounds the internal connection portion of at least one of the pair of electrode connection terminals corresponding to the at least one electrode.

[0011] According to the present invention, at least one electrode of a pair of electrodes of multiple capacitance elements, corresponding to the internal connection portion of at least one electrode connection terminal, is electrically connected to the internal connection portion of at least one electrode connection terminal, with the electrodes arranged to surround the internal connection portion. This allows a large number of capacitance elements to be electrically connected directly, reliably, and compactly to the terminal, thereby enabling miniaturization of the capacitance device and improvement of the required performance.

[0012] In the present invention, it is preferable that the internal connection portion of at least one electrode connection terminal is configured in an axial shape, and that at least one electrode of the plurality of capacitance elements is arranged around the axis of the internal connection portion so as to surround the axial internal connection portion. With this configuration, since the internal connection portion surrounded by the plurality of capacitance elements is configured in an axial shape, it is easier to arrange the capacitance elements conductively connected to the internal connection portion around its entire circumference. This makes it possible to further improve the required performance by increasing the number of capacitance elements conductively connected to the internal connection portion while ensuring miniaturization of the device.

[0013] In the present invention, the capacitance element is a rod-shaped capacitance element having a coaxial laminated structure in which the pair of electrodes are axial, and it is preferable that it is arranged in a position along the axis. With this arrangement, sufficient capacitance can be secured even with a small cross-sectional area by having a coaxial laminated structure, and it is easier to electrically connect a large number of capacitance elements around each internal connection part, thereby enabling further miniaturization and improvement of required performance. In this case, it is preferable that the capacitance element is made up of a dielectric layer, an electrolytic layer, and a cathode sequentially stacked coaxially with an axial anode at the center. Here, it is even more preferable that the electrolytic layer contains a solid electrolyte made of a conductive polymer.

[0014] In the present invention, it is preferable that the external dimensions (including the outer diameter; the same applies hereinafter) or circular equivalent diameter of the internal connection portion of at least one electrode connection terminal is greater than or equal to the external dimensions or circular equivalent diameter of the electrode surrounding the internal connection portion. This makes it possible to increase the number of capacitance elements having electrodes directly conductively connected around the internal connection portion, thereby enabling further miniaturization and improvement of required performance.

[0015] In the present invention, it is preferable that the plurality of capacitance elements include capacitance elements whose electrode external dimensions or circular diameters differ from each other. This makes it possible to improve the arrangement efficiency of the plurality of electrodes by including capacitance elements with electrodes of different external dimensions or circular diameters, thereby increasing the number of electrodes that can be arranged around the internal connection part. As a result, the number of capacitance elements that are directly conductively connected around the internal connection part can be increased, which makes it possible to further miniaturize the device and improve the required performance.

[0016] In the present invention, it is preferable that the external dimensions or circular diameter of the internal connection portion provided on at least one of the electrode connection terminals are greater than or equal to the external dimensions or circular diameter of the external connection portion of the electrode connection terminal. This makes it possible to increase the number of capacitance elements that are arranged around the internal connection portion and directly conductively connected, thereby enabling further miniaturization and improvement of required performance. [Effects of the Invention]

[0017] According to this invention, in a capacitance device in which multiple capacitance elements are electrically connected in parallel, it is possible to miniaturize the product while improving the required performance. [Brief explanation of the drawing]

[0018] [Figure 1] This is a longitudinal cross-sectional view of a capacitance device according to the first embodiment of the present invention. [Figure 2] These are cross-sectional views AA (a) and BB (b) of the first embodiment, as well as the left side view (c), front view and rear view (d), right side view (e), top view (f), and bottom view (g), each reduced to half size. [Figure 3] (a) and (b) are longitudinal cross-sectional views of the capacitance element of the first embodiment, and (c) and (d) are enlarged partial cross-sectional views. [Figure 4]These are the A-A cross-sectional view (a) and B-B cross-sectional view of the capacitor device according to the second embodiment of the present invention. [Figure 5] These are the A-A cross-sectional view (a) and B-B cross-sectional view of the capacitor device according to a modified example of the second embodiment of the present invention. [Figure 6] These are the A-A cross-sectional view (a) and B-B cross-sectional view (b) of the capacitor device according to the third embodiment of the present invention. [Figure 7] These are the A-A cross-sectional view (a) and B-B cross-sectional view (b) of the capacitor device according to the fourth embodiment of the present invention. [Figure 8] These are the A-A cross-sectional view (a) and B-B cross-sectional view (b) of the capacitor device according to the fifth embodiment of the present invention. [Figure 9] This is the longitudinal cross-sectional view of the capacitor device according to the sixth embodiment of the present invention. [Figure 10] These are schematic explanatory views (a)-(g) schematically showing the manufacturing process of the capacitor element in each embodiment according to the present invention. [Figure 11] This is a schematic perspective view schematically showing the manufacturing method of the capacitor device in each embodiment according to the present invention.

Embodiments for Carrying Out the Invention

[0019] Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0020] (First Embodiment) First, referring to FIGS. 1 to 3, the first embodiment of the capacitor device according to the present invention will be described. FIG. 1 is a longitudinal cross-sectional view showing the internal structure of the capacitor device 1, and FIG. 2 is a cross-sectional view (a) along the A-A line shown in FIG. 1, a cross-sectional view (b) along the B-B line, a left side view (c), a front view (d), a right side view (e), a plan view (f), and a bottom view (g). However, the left side view (c), the front view (d), the right side view (e), the plan view (f), and the bottom view (g) are drawn at a scale of 1 / 2 compared to FIGS. 1, 2(a), and (b). Note that the rear view appears the same as the front view (d) above.

[0021] The capacitance device 1 comprises a plurality of capacitance elements 2, an anode connection terminal 3 having an internal connection portion 31 conductively connected to the anode 21 of the capacitance elements 2 and an external connection portion 32 configured to be electrically connected to the outside, a cathode connection terminal 4 having an internal connection portion 41 conductively connected to the cathode 25 of the capacitance elements 2 and an external connection portion 42 configured to be electrically connected to the outside, and a sealing material 5 made of an insulating epoxy resin or other molding resin, or an exterior coating made of resin, such as epoxy or acrylic resin, which seals the plurality of capacitance elements 2, the internal connection portion 31 of the anode connection terminal 3 and the internal connection portion 41 of the cathode connection terminal 4. The external connection portion 32 of the anode connection terminal 3 and the external connection portion 42 of the cathode connection terminal 4 are both configured to protrude from both sides of the axis 1x of the device body, whose outer shape is formed by the sealing material 5. In the illustrated example, the external connection parts 32 and 42 each have a shape that protrudes in the direction of axis 1x, then bends and extends in a direction substantially perpendicular to axis 1x.

[0022] In this embodiment, the anode connection terminal 3 and the cathode connection terminal 4 constitute a pair of electrode connection terminals 3 and 4, and these electrode connection terminals 3 and 4 are equipped with internal connection parts 31 and 41 and external connection parts 32 and 42. When referring to the pair of electrode connection terminals 3 and 4, it means that it refers to at least one of the anode connection terminal 3 and the cathode connection terminal 4. The same applies when referring to the pair of internal connection parts 31 and 41 or the pair of external connection parts 32 and 42. Also, in this embodiment, the anode 21 and the cathode 25 constitute a pair of electrodes 21 and 25. When referring to the pair of electrodes 21 and 25, it means that it refers to at least one of the anode 21 and the cathode 25.

[0023] In the first embodiment, the internal connection portion 31 of the anode connection terminal 3 is configured in an axial shape (cylindrical in the illustrated example) and is arranged along the axis 1x of the capacitance device 1 (which is also the axis of the internal connection portion 31). Similarly, the internal connection portion 41 of the cathode connection terminal 4 is also configured in an axial shape (cylindrical in the illustrated example) and is arranged along the axis 1x of the capacitance device 1. The plurality of capacitance elements 2 are formed as rod-shaped (cylindrical in the illustrated example) capacitance elements in which both the anode 21 and cathode 25 are axial (cylindrical in the illustrated example) and the internal structure is stacked coaxially. These capacitance elements 2 are all arranged parallel to each other along the axis 1x. In the illustrated example, the anode 21 of the capacitance element 2 is provided on one end side (near the end) in the direction of axis 1x. The cathode 25 of the capacitance element 2 is provided on the other end side in the direction of axis 1x. Both the anode 21 and the cathode 25 have a cylindrical outer surface which is the outer surface of the overall rod-shaped structure.

[0024] As shown in Figure 2(a), the anodes 21 of the multiple capacitance elements 2 are electrically connected to the outer surface of the internal connection portion 31 of the anode connection terminal 3, with the internal connection portion 31 being arranged around the axis 1x of the internal connection portion 31 along the axis 1x. The method of conductive connection between the anode 21 and the internal connection portion 31 is not particularly limited, but in the illustrated example, it is preferable to make the conductive connection by welding such as laser welding or resistance welding, or welding by heating.

[0025] As shown in Figure 2(b), the cathodes 25 of the multiple capacitance elements 2 are electrically connected to the outer surface of the internal connection portion 41 of the cathode connection terminal 4, which is located along the axis 1x, with the internal connection portion 41 being arranged to surround the axis 1x. The method of conductive connection between the cathode 25 and the internal connection portion 41 is not particularly limited, but in the illustrated example, it is preferable to connect them electrically by brazing, conductive adhesive, or welding by heating.

[0026] As shown in Figures 1 and 2, in this embodiment, multiple (four in the illustrated example) capacitance elements 2 are arranged around the internal connection portion 31 of the axial anode connection terminal 3 and the internal connection portion 41 of the cathode connection terminal 4, respectively, so as to surround the axis. In this arrangement, the multiple capacitance elements 2 are electrically connected to each other via the anode connection terminal 3 (anodes 21) and to each other via the cathode connection terminal 4 (cathodes 25). As a result, the multiple capacitance elements 2 are electrically connected in parallel between the anode connection terminal 3 and the cathode connection terminal 4.

[0027] Figure 3 is a longitudinal cross-sectional view showing the internal structure of the capacitance element 2. The capacitance element 2 has a structure in which a dielectric thin film 22, a conductive polymer layer 23, an inner electrode layer 24, and an outer electrode layer, which is a cathode 25, are coaxially stacked around an anode 21. Specifically, for example, the surface of an axial (center) conductor made of a valve metal such as aluminum is widened by etching, and then a dielectric thin film 22 made of, for example, an oxide film is formed by anodizing. After that, a conductive polymer layer 23 made of a conductive polymer such as polypyrrole or polythiophene is formed on the dielectric thin film 22 by, for example, repeating the process of coating and drying. On the conductive polymer layer 23, an inner electrode layer 24 is formed by coating and drying a conductive material (resin) such as carbon paste, and then an outer electrode layer 25 is formed by coating and drying a conductive material (resin) such as silver paste. In the illustrated example, the capacitance element 2 is shown as constituting a conductive polymer solid capacitor, but this is not particularly limited. It may also be a hybrid type capacitor using a conductive polymer, or other types of capacitors that do not use a conductive polymer.

[0028] In this case, by coaxially stacking the anode 21, dielectric thin film 22, conductive polymer layer 23, inner electrode layer 24, and outer electrode layer 25, a high capacitance can be obtained while maintaining a compact capacitance element 2. However, the capacitance element 2 is not limited to the above structure; it may also have a plate-like stacked structure. Furthermore, the manufacturing method of the capacitance element 2 is not limited to the method described above, which involves forming a stacked structure by applying various treatments (film formation by immersion and drying, etc.) around an axial or central conductor. Instead, a stacked structure may be formed by winding or overlapping sheet-like structural materials.

[0029] As shown in Figure 3, the structure of the capacitance element 2 preferably involves forming an insulating film 26 made of an insulating material (resin) on a predetermined surface region of the axial (central) conductor 21, thereby preventing short circuits between the conductor 21 and the conductive polymer layer 23, inner electrode layer 24, and outer electrode layer 25. Here, the conductive layers such as the conductive polymer layer 23, inner electrode layer 24, and outer electrode layer 25 are formed so that their ends are within the range where the insulating film 26 is formed.

[0030] In this embodiment, the axial (central) conductor 21 is the anode and the outer electrode layer 25 is the cathode. However, any capacitance element 2 is not limited to this configuration; it is sufficient to have a pair of electrodes 21 and 25. Therefore, in this specification, when referring to any capacitance element 2, it is stated that it is provided with a pair of electrodes. Furthermore, other types of capacitors and capacitors may have different internal structures, such as dielectric thin films 22 and conductive polymer layers 23, so the internal structure of any capacitance element 2 is not limited to the above-mentioned internal structure.

[0031] In this embodiment, it is preferable that the outer diameter of the internal connection portions 31 and 41 of the electrode connection terminals 3 and 4 is greater than or equal to (more preferably greater than) the outer diameter of the corresponding electrodes 21 and 25 of the capacitance element 2. In this case, it is assumed that both the internal connection portions 31 and 41 and the electrodes 21 and 25 have a circular cross-section. However, if the internal connection portions 31 and 41 and the electrodes 21 and 25 have any similar shape, the relationship between their external dimensions is also the same, and it is preferable that the external dimensions of the internal connection portions 31 and 41 are greater than or equal to (more preferably greater than) the external dimensions of the corresponding electrodes 21 and 25 of the capacitance element 2. Furthermore, if the diameter of a circle having the same cross-sectional area as the cross-section perpendicular to the axis 1x is defined as the circular equivalent diameter, it is preferable that the circular equivalent diameter of the internal connection portions 31 and 41 is greater than or equal to (more preferably greater than) the circular equivalent diameter of the corresponding electrodes 21 and 25 of the capacitance element 2. Generally, when the internal connection parts 31, 41 and electrodes 21, 25 have arbitrary shapes, it is necessary that multiple (two or more) electrodes 21, 25 are arranged around the internal connection parts 31, 41 so that they can be directly electrically connected. Here, the number of electrodes (capacitance elements) is more preferably three or more, and preferably four or more. In any case, increasing the external dimensions of the internal connection parts 31, 41 relative to the external dimensions of the capacitance element 2 increases the spatial margin that allows multiple capacitance elements 2 to be arranged around them.

[0032] In this embodiment, for electrode connection terminals 3 and 4, the external dimensions or circular equivalent diameter of the internal connection parts 31 and 41 are preferably greater than or equal to the external dimensions or circular equivalent diameter of the external connection parts 32 and 42 (more preferably greater). In this case, the external dimensions and circular equivalent diameter are the same as described above. Generally, the shape and dimensions (especially the cross-sectional shape and cross-sectional dimensions) of the external connection parts 32 and 42 are often determined by standards and circuit configuration considerations, but the internal connection parts 31 and 41 can be determined according to the characteristics and number of capacitances 2, as well as their internal conductive connection structure, which correspond to the required performance as a capacitance device 1, without being directly related to the shape and dimensions of the external connection parts 32 and 42. In any case, increasing the external dimensions of the internal connection parts 31 and 41 relative to the external dimensions of the external connection parts 32 and 42 increases the spatial margin necessary to arrange multiple capacitance elements 2 surrounding them.

[0033] In this embodiment, the anode 21 of the capacitance element 2 is constructed by laminating a dielectric thin film 22, a conductive polymer layer 23, an inner electrode layer 24, and an outer electrode layer 25 around an axial (center) conductor constituting the anode 21. As shown in Figure 3, the external dimensions or circular equivalent diameter of the anode 21 are configured to be slightly smaller than the external dimensions or circular equivalent diameter of the cathode 25. To absorb this difference in external dimensions or circular equivalent diameter ΔR1 (difference in radius in the illustrated example, hereinafter simply referred to as "dimensional difference"), in the illustrated example, the external dimensions or circular equivalent diameter of the internal connection portion 31 of the anode connection terminal 3 are configured to be slightly larger (preferably by the same absolute value as the above-mentioned dimensional difference ΔR1) than the external dimensions or circular equivalent diameter of the internal connection portion 41 of the cathode connection terminal 4. The dimensional difference ΔR2 (see Figure 1) between the internal connection portions 31 and 41 at this time does not necessarily have to be the same as the above-mentioned dimensional difference ΔR1, but it is desirable that ΔR1 and ΔR2 be configured to cancel each other out. However, since the dimensional difference ΔR1 between the anode 21 and the cathode 22 is small, it can be absorbed by the slight deflection of the capacitance element 2 in the direction of the axis 1x or by the difference in thickness of the conductive connection layer (not shown, corresponding to the conductor layers 27, 28, 19, etc., described later) at the conductive connection point between the anode 21 and the cathode 25. Therefore, the dimensional difference ΔR2 between the internal connection parts 31 and 41 can be provided or not provided. This point is the same in other embodiments.

[0034] In this embodiment, by arranging multiple capacitance elements 2 around the internal connection parts 31 and 41 of the electrode connection terminals 3 and 4 so as to surround the internal connection parts 31 and 41 and connecting them electrically, it is possible to directly connect a larger number of capacitance elements 2 to the electrode connection terminals 3 and 4 while keeping the overall size compact. This makes it possible to reduce the size of the product and improve various required performances, such as lower ESR and ESL, lower costs for the internal conductive connection structure, and improved electrical reliability.

[0035] In particular, by configuring the internal connection portions 31 and 41 of the electrode connection terminals 3 and 4 in an axial shape, and by electrically connecting multiple capacitance elements 2 in a manner that surrounds these axial internal connection portions 31 and 41, it becomes possible to easily and effectively construct the conductive connection structure between the electrodes and terminals, thereby improving electrical reliability. Furthermore, since the conductive connection structure can be easily manufactured, manufacturing costs can be reduced. Especially, as shown in the illustrated example, by configuring the internal connection portions 31 and 41 in a cylindrical shape, it becomes possible to easily and reliably electrically connect multiple capacitance elements 2, thereby further reducing manufacturing costs and significantly improving reliability.

[0036] Furthermore, when arranging multiple capacitance elements 2 on the outer circumference of the internal connection parts 31 and 41, it is preferable to arrange them in a manner that provides rotational symmetry around the axis, as shown in the illustrated example, in order to create an efficient arrangement, and it is particularly desirable to set a high degree of isotropy around the axis. This enables efficient use of space and makes it easier to achieve both miniaturization and improved performance (high capacity, low ESR, low ESL, etc.). Another condition for improving isotropy is to arrange multiple capacitance elements 2 that have the same external shape and dimensions as each other. Further conditions for improving the rotational symmetry and isotropy include, as mentioned above, having circular cross-sections (cylindrical shapes) for the internal connection parts 31 and 41, having circular cross-sections (cylindrical shapes) for the capacitance elements 2, and increasing the number of capacitance elements 2 directly conductively connected to the internal connection parts 31 and 41.

[0037] Furthermore, in this embodiment, since the capacitance element 2 is configured in a rod shape with an axial electrode structure, a large number of capacitance elements 2 can be efficiently arranged around the internal connection parts 31 and 41, thereby further reducing the product size and improving the required performance. In addition, the cylindrical shape of the capacitance element 2 allows for further reduction of manufacturing costs and a significant improvement in reliability. Moreover, since the capacitance element 2 has a coaxial stacked structure, it becomes easier to further reduce the size and increase the capacitance of the capacitance element 2.

[0038] While capacitance and ESR tend to increase with larger external dimensions of capacitance element 2, increasing external dimensions also increases the size of the capacitance device 1. Therefore, by arranging a large number of capacitance elements 2 with relatively small external dimensions on the outer circumference of the internal connection parts 31 and 41, it is possible to achieve both miniaturization of the capacitance device 1 and improvement of the required performance.

[0039] The dimensions of the internal structure of the capacitance device 1 are not particularly limited, but are preferably within the following ranges. The external dimensions of the capacitance element 2 are preferably within the range of 100 μm to 10 mm in terms of circular diameter, and more preferably within the range of 0.2 mm to 5 mm. In this case, the external dimensions of the internal connection parts 31 and 41 of the electrode connection terminals 3 and 4 are preferably within the range of 200 μm to 30 mm in terms of circular diameter, and more preferably within the range of 0.5 mm to 15 mm. Furthermore, as for the internal structure of the capacitance element 2, in the above case, it is preferable that the thickness of the dielectric thin film 22 is within the range of 1 nm to 2 μm, the thickness of the conductive polymer layer 23 is within the range of 10 nm to 10 μm, and the thickness of the inner electrode layer 24 and outer electrode layer 25 are within the range of 50 nm to 50 μm. However, it is desirable that the thickness of the inner electrode layer 24 and outer electrode layer 25 be within the range of 20 μm or less within the above range in order to achieve both miniaturization and high capacitance of the product.

[0040] As shown in FIG. 1, when the length of the central electrode (anode 21) of the capacitance element 2 is S and the length of the outer peripheral electrode (cathode 25) is L, since S < L, it is possible to make the capacitance element 2 compact while ensuring a large capacitance value of the capacitance element 2. In this case, it is preferable that S is less than 0.5 times and more than 0.05 times of L, and it is desirable that S is less than 0.3 times and more than 0.1 times of L. This also contributes to achieving both a large capacitance and a compact size of the capacitance device 1.

[0041] Further, when the length of the conductive connection region between the outer peripheral electrode (cathode 25) and the corresponding electrode terminal (internal connection portion 41) is P, it is preferable that P is within the range of L×0.3≦P≦L. In this case, with respect to the lower limit, it is more preferable that P is 0.5 times or more of L, and even more preferable that P is 0.7 times or more of L. Also, with respect to the upper limit, it is more preferable that P is 0.95 times or less of L, and even more preferable that P is 0.9 times or less of L. This is because the electrical resistance of the outer peripheral electrode (cathode 25) (actually, the electrical resistance of the laminated structure of 23, 24, and 25 mentioned above) is much larger than the electrical resistance of the corresponding electrode terminal (internal connection portion 41). Therefore, it is important to increase the conductive connection area between the outer peripheral electrode (cathode 25) and the corresponding electrode terminal (internal connection portion 41). As in the preferable range regarding the lower limit mentioned above, in order to increase the conductive connection area and achieve lower ESR and lower ESL, the closer P is to L (ideally, P = L), the better. However, if P is made too close to L, the risk of short - circuit between the two electrodes 21 and 25 increases. Therefore, the preferable range regarding the upper limit mentioned above is desired. Note that this risk is reduced by the presence of the insulating film 26 mentioned above.

[0042] Furthermore, since the difference in electrical resistance between the central electrode (anode 21) and the corresponding electrode terminal (internal connection part 31) is considered to be small, the conductive connection area between the central electrode (anode 21) and the corresponding electrode terminal (internal connection part 31) is considered to have less impact on ESR and ESL than the conductive connection area between the outer electrode (cathode 25) and the corresponding electrode terminal (internal connection part 41). In addition, even if a dielectric thin film 22 is present on the surface of the central electrode (anode 21), it is considered possible to eliminate adverse effects on ESR and ESL by making a conductive connection in a good contact state by welding or the like.

[0043] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to Figure 4. The capacitance device 1 of this embodiment differs from the first embodiment only in the internal structure shown in Figures 2(a) and (b). Since other parts can be configured in the same way as the first embodiment shown in Figures 1 and 2(c)-(g), a description of the parts that can be configured in the same way will be omitted.

[0044] In this embodiment, as shown in Figure 4(b), not only are the cathodes 25 of multiple capacitance elements 2 electrically connected to the internal connection part 41, but the cathodes 25 of multiple capacitance elements 2 adjacent to each other in the circumferential direction (around the axis 1x) are also electrically connected to each other. In the illustrated example, as shown in Figure 4(a), the anodes 21 adjacent to each other in the circumferential direction (around the axis 1x) that are electrically connected to the internal connection part 31 are spaced apart from each other.

[0045] In the example shown in Figure 5(a), a conductive layer 27 is formed around the anode 21, and the anodes 21 are electrically connected to each other in the circumferential direction (around the axis) via this conductive layer 27. That is, in this example, not only adjacent cathodes 25 but also adjacent anodes 21 are electrically connected to each other. The conductive layer 27 is preferably formed by applying a conductive material such as a conductive adhesive around the anode 21 (preferably all around) to a thickness (thickness corresponding to the dimensional difference ΔR1 mentioned above) such that the anode 21 has the same external dimensions (outer diameter) as the cathode 25. In addition to providing a conductive layer 27 on the anode 21 as described above, a conductive layer similar to the above may also be applied around the electrodes 21 and 25 (preferably all around) using a conductive adhesive or the like in order to directly electrically connect adjacent electrodes 21 and 25 in the circumferential direction (around the axis 1x). In this example, the dimensional difference ΔR2 between the internal connection parts 31 and 41 can be reduced (eliminated) by making the thickness of the conductor layer 27 close to (match) the dimensional difference ΔR1 between the anode 21 and cathode 25 of the capacitance element 2.

[0046] In this embodiment, by directly conductively connecting adjacent electrodes 21 and 25 of multiple capacitance elements 2 in the circumferential direction (around the axis 1x), the mechanical strength of the array structure of electrodes 21 and 25, which are already configured to be conductively connected to the internal connection parts 31 and 41, can be improved. Furthermore, by directly conductively connecting the electrodes 21 and 25 to each other, the connection resistance and inductance of the conductive connection structure can be reduced, thereby enabling further reduction of ESR and ESL of the capacitance device 1.

[0047] Furthermore, the fact that electrodes 21 and 25 of multiple capacitance elements 2 are directly conductively connected to each other in the circumferential direction (around the axis 1x) means that a large number of capacitance elements 2 are usually densely arranged on the outer surface of the internal connection parts 31 and 41 of the electrode connection terminals 3 and 4. This also increases the number of capacitance elements 2 connected in parallel, which makes it easier to further improve the required performance, including increasing the capacitance of the capacitance device 1. Moreover, in this embodiment, the rotational symmetry and isotropy are further enhanced compared to the first embodiment, making it a more preferable example from the viewpoint of miniaturizing the capacitance device 1 and improving the required performance.

[0048] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to Figure 6. The capacitance device 1 of this embodiment differs from the first embodiment only in the internal structure shown in Figures 2(a) and (b). Since other parts can be configured in the same way as the first embodiment shown in Figures 1 and 2(c)-(g), a description of the parts that can be configured in the same way will be omitted.

[0049] In this embodiment, as shown in Figure 6, capacitance elements 2a and 2b with mutually different external dimensions or circular diameters exist around the internal connection parts 31 and 41 of the electrode connection terminals 3 and 4, which distinguishes it from the previous embodiments. If a large number of capacitance elements 2 with the same shape and the same external dimensions or circular diameters were to be arranged around the internal connection parts 31 and 41 of the electrode connection terminals 3 and 4, as in the second embodiment, the external dimensions or circular diameters of the capacitance elements 2 would be constrained by their relationship to the external dimensions or circular diameters of the internal connection parts 31 and 41, resulting in a decrease in the degree of freedom in product design. In contrast, as in this embodiment, by including capacitance elements 2a and 2b with mutually different external dimensions or circular diameters, it becomes possible to efficiently arrange even more capacitance elements around the internal connection parts 31 and 41 by changing the combination (number and arrangement) of different capacitance elements, without changing the external dimensions or circular diameters of the capacitance elements 2a and 2b themselves.

[0050] In this embodiment, as shown in Figure 6(b), the cathodes 25a and 25b of capacitance elements 2a and 2b of different dimensions are connected to each other in an adjacent manner, thereby achieving the same effects as in the second embodiment. In this case, it is conceivable that the dimensional difference ΔR1 may differ between capacitance elements 2a and 2b having different dimensions, so a conductor layer 28 may be provided as a buffer layer for conductively connecting all anodes 21a and 21b to the internal connection part 31, as shown in Figure 6(a). In this example as well, a conductor layer similar to the conductor layer 27 shown in Figure 5(a) may be used to conductively connect anodes 21a and 21b.

[0051] In the illustrated example, capacitance elements 2a and 2b with two different external dimensions or circular diameters are used, but capacitance elements with three or more different external dimensions or circular diameters may be used. Furthermore, capacitance elements with different shapes, not just external dimensions or circular diameters, may be combined. While increasing the variety of dimensions and shapes makes manufacturing more difficult, it allows for a higher level of miniaturization and improvement of required performance.

[0052] (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to Figure 7. The capacitance device 1 of this embodiment differs from the first embodiment only in the internal structure shown in Figures 2(a) and (b). Since other parts can be configured in the same way as the first embodiment shown in Figures 1 and 2(c)-(g), a description of the parts that can be configured in the same way will be omitted.

[0053] This embodiment shows an example in which the cross-sectional shape of the internal connection portions 31 and 41 of the electrode connection terminals 3 and 4 and the cross-sectional shape of the capacitance element 2 differ from those of other embodiments. In the illustrated example, the cross-sectional shape of the internal connection portions 31 and 41 is rectangular (square or rectangular), and the cross-sectional shape of the capacitance element 2 is also rectangular (square or rectangular). Thus, in this embodiment, the cross-sectional shape of the axial internal connection portions 31 and 41 is not circular as in other embodiments, and the cross-sectional shape of the capacitance element 2 is not coaxial. However, in this embodiment, the fact that the internal connection portions 31 and 41 are axial is common to other embodiments, and the fact that the capacitance element 2 is rod-shaped is also common to other embodiments. Therefore, as a result, the aforementioned effects can be achieved in the same way.

[0054] In this embodiment, as described above, the internal connection parts 31 and 41 are axial and the capacitance element 2 is rod-shaped, similar to other embodiments. However, in the present invention, the internal connection parts 31 and 41 and the capacitance element 2 may be plate-shaped (thin plate-shaped). For example, as an example of a plate shape, the aspect ratio of the rectangular cross-section may be 5 or more. If the internal connection parts 31 and 41 are plate-shaped, it is conceivable that the capacitance element 2 may be arranged only on the front and back surfaces of the internal connection parts 31 and 41. Even so, the fact that multiple capacitance elements 2 are arranged to surround the internal connection parts 31 and 41 remains unchanged. Also, if the capacitance element 2 is plate-shaped, it will be stacked in layers around the internal connection parts 31 and 41. Even so, the fact that multiple capacitance elements 2 are arranged to surround the internal connection parts 31 and 41 and are directly electrically connected remains unchanged.

[0055] (Fifth embodiment) Next, a fifth embodiment of the present invention will be described with reference to Figure 8. The capacitance device 1 of this embodiment differs from the first embodiment only in the internal structure shown in Figures 2(a) and (b). Since other parts can be configured in the same way as the first embodiment shown in Figures 1 and 2(c)-(g), a description of the parts that can be configured in the same way will be omitted.

[0056] In this embodiment, in addition to a plurality of capacitance elements 2A having electrodes 21A, 25A directly conductively connected to the outer circumferential surfaces of the internal connection portions 31, 41 of electrode connection terminals 3, 4, an example is shown in which electrodes 21B, 25B of a further plurality of capacitance elements 2B are conductively connected to the outer circumferential sides of these plurality of capacitance elements 2A. The electrodes 21B, 25B of capacitance elements 2B are not directly conductively connected to the internal connection portions 31, 41, but are directly conductively connected to the electrodes 21A, 25A of capacitance elements 2A.

[0057] In this embodiment, the configuration described above allows for the conductive connection of a larger number of capacitance elements in parallel, thereby enabling further increases in capacitance and performance of the capacitance device 1. In particular, the second layer capacitance element 2B is conductively connected to the two first layer capacitance elements 2A, which is advantageous in terms of reducing ESR and ESL. Furthermore, a conductive layer 29 similar to that described above can be provided to overcome the dimensional difference ΔR1 and ensure conductive connection between the anodes 21A and 21B. In addition, capacitance elements from the third layer onward that are conductively connected to the first and second layer capacitance elements may also be provided.

[0058] (Sixth Embodiment) Next, with reference to Figure 9, a sixth embodiment of the present invention will be described. The capacitance device 1 of this embodiment differs from the first embodiment only in the internal structure shown in Figures 2(a) and (b). Since other parts can be configured in the same way as the first embodiment shown in Figures 1 and 2(c)-(g), a description of the parts that can be configured in the same way will be omitted.

[0059] In this embodiment, the conductive connection structure between the internal connection portion 41 of the cathode connection terminal 4 and the cathode 25 of the capacitance element 2 is the same as in the previous embodiments, but an example is shown in which the conductive connection structure between the internal connection portion 31 of the anode connection terminal 3 and the anode 21 of the capacitance element 2 is different. The internal connection portion 31 of the anode connection terminal 3 is conductively connected to the anodes 21 provided on the plurality of capacitance elements 2 in the direction of axis 1x. That is, the internal connection portion 31 is configured to be conductively connected to the end faces of the plurality of anodes 21. Even with this configuration, the conductive connection structure between the internal connection portion 41 of the cathode connection terminal 4 and each cathode 25 of the plurality of capacitance elements 2 remains unchanged, so there is almost no difference in terms of miniaturization of the product and improvement of required performance. In the illustrated example, there is a small portion of the internal connection portion 31 that is located inside the plurality of anodes 21, so the aforementioned conductive connection structure in which the anodes 21 surround the internal connection portion 31 is not entirely absent, but the conductive connection area is reduced. Furthermore, even without the internal components described above, the product can be manufactured electrically. However, in order to secure a sufficient conductive connection area, it may be necessary to extend the internal connection section 31 to the outer circumference of the anode 21, and the absence of the aforementioned conductive connection structure may result in a situation that contradicts the miniaturization of the capacitance device 1.

[0060] In the illustrated example, the conductive connection structure between the internal connection portion 31 of the anode connection terminal 3 and each cathode 25 of the plurality of capacitance elements 2 can further reduce the dimension in the direction along the axis 1x, and instead, the increase in conductivity resistance can be suppressed by making the end face of the anode 21 the conductive connection surface. Furthermore, this embodiment shows that the above-mentioned effects can also be achieved by adopting the above-mentioned conductive connection structure in which one of the electrodes, either the anode 21 or the cathode 25 of the corresponding capacitance element 2, surrounds one of the internal connection portions 31 and 41 of the electrode connection terminals 3 and 4. Regardless of whether the above-mentioned conductive connection structure is adopted or not, the internal connection portions 31 and 41 can also be configured to be electrically connected to the end faces of the electrodes 21 and 25, thereby further improving the required performance.

[0061] The configurations of the first to sixth embodiments described above can be adopted in any combination, as long as they do not interfere with each other.

[0062] (Manufacturing method) Finally, the manufacturing method of the capacitance element 2 will be explained with reference to Figure 10, and the manufacturing method of the capacitance device 1 using the capacitance element 2 will be explained with reference to Figure 11. As shown in Figure 10(a), first, a surface widening treatment is applied to the axial (center) conductor 21 of a valve metal such as aluminum to form a fine uneven surface, then a dielectric thin film 22 is formed by anodizing or the like, and then, as shown in Figure 10(b), an insulating resin is applied to a predetermined region in the axial direction to form an insulating film 26.

[0063] Next, as shown in Figure 10(c), multiple anodes 21 are attached to a support member (jig) 51, and as shown in Figure 10(d), the anodes 21 are immersed in a conductive polymer solution prepared in a processing tank 52, and then lifted out and dried to form a conductive polymer layer 23. In practice, repeating this process multiple times makes it easier to obtain the required performance of the electrolytic layer. As shown in Figure 10(e), this conductive polymer layer 23 is formed on the dielectric thin film 22 so that its outer edge is within the area where the insulating film 26 is formed. Then, as shown in Figure 10(f), the inner electrode layer 24 and outer electrode layer 25 are formed by immersion in a conductive solution (such as carbon paste or silver paste) prepared in a processing tank 53 and drying. Furthermore, by manufacturing multiple capacitance elements in parallel using a method of immersion processing in processing tanks 52 and 53 while they are suspended using the support member 51, it is possible to improve manufacturing efficiency, such as reducing manufacturing costs.

[0064] As shown in Figure 11, the capacitance elements 2 manufactured as described above are assembled onto a lead frame 60 on which electrode connection terminals 3 and 4 are formed, and the electrodes 21 and 25 are joined to the internal connection parts 31 and 41 by conductive adhesive or laser welding. At this time, electrode connection terminals 3 and 4 corresponding to the lead parts 62 are formed on the frame part 61 of the lead frame 60, and the internal connection parts 31 and 41 are formed to connect to the frame part 61 of the lead frame 60. Then, it is desirable to manufacture the internal structure of the capacitance device 1 by attaching multiple capacitance elements 2 to these internal connection parts 31 and 41 as shown by the dashed line in the figure and performing the conductive connection work described above. After that, the capacitance device 1 is manufactured by performing a sealing step in which each internal structure is sealed with a sealing material 5 and a disconnection step in which the external connection parts 32 and 42 are separated from the frame part 61 of the lead frame 60.

[0065] Typically, a conductive connection structure is formed by directly assembling multiple capacitance elements 2 to the internal connection parts 31 and 41, and then performing conductive connection work such as welding, brazing, or bonding while the assembled configuration is held in place by some kind of retaining member. In this case, since the multiple capacitance elements 2 are directly conductively connected to the outer circumferential surfaces of the internal connection parts 31 and 41, the conductive connection work can be easily performed, and electrical reliability can also be ensured. Furthermore, the ease of the conductive connection work can reduce manufacturing costs.

[0066] In this case, although not shown in the figures, multiple lead portions 62 may be connected to the frame portion 61 of the lead frame 60, and electrode connection terminals 3 and 4 may be formed on each of the lead portions 62. In this way, since multiple sets of electrode connection terminals 3 and 4 are formed on a common lead frame 60, multiple capacitance devices 1 can be manufactured in parallel by applying multiple capacitance elements 2 to each lead portion 62.

[0067] Furthermore, although a dielectric thin film 22 is formed on the surface of the anode (conductor) 21, welding or brazing is used when electrically connecting the anode 21 to the internal connection part 31 so that the dielectric thin film 22 does not interfere with the conductive connection.

[0068] It should be noted that the capacitance device of the present invention is not limited to the illustrated examples described above, and various modifications can be made without departing from the spirit of the present invention. For example, in each of the above embodiments, a pair of electrodes of multiple capacitance elements are electrically connected on the internal connection portion of a pair of axial electrode connection terminals, with each pair of electrodes surrounding the axis. However, the present invention is not limited to this form, and it is sufficient that the electrodes of multiple capacitance elements are electrically connected on the internal connection portion of the electrode connection terminals, with each electrode surrounding the axis. [Explanation of symbols]

[0069] 1...Capacitance device, 2...Capacitance element, 21...Anode (electrode), 22...Dielectric thin film, 23...Solid electrolytic layer, 24...Inner electrode layer, 25...Cathode (outer electrode layer, electrode), 26...Insulating film, 27~29...Conducting layer, 3...Anode connection terminal (electrode connection terminal), 31...Internal connection part, 32...External connection part, 4...Cathode connection terminal (electrode connection terminal), 41...Internal connection part, 42...External connection part, 5...Sealing material (molding resin), 51...Support member, 52,53...Processing tank, 60...Lead frame, 61...Frame part, 62...Lead part

Claims

1. Multiple capacitance elements, each having a pair of electrodes, The plurality of capacitance elements have a pair of electrode connection terminals, each having an internal connection portion electrically connected to one and the other of the pair of electrodes, and an external connection portion electrically connected to the outside, A capacitance device in which the plurality of capacitance elements are connected in parallel by the pair of electrode connection terminals, A capacitance device characterized in that at least one of the pair of electrodes in the plurality of capacitance elements is electrically connected in such a way that it surrounds the internal connection portion of at least one of the pair of electrode connection terminals that corresponds to the at least one electrode.

2. The internal connection portion of at least one of the electrode connection terminals is configured in an axial shape, and the at least one electrode of the plurality of capacitance elements is arranged around the axis of the internal connection portion so as to surround the axial internal connection portion. The capacitance device according to claim 1.

3. The capacitance element is a rod-shaped capacitance element having a coaxial stacked structure in which the pair of electrodes are axial, and is arranged in a position along the axis. The capacitance device according to claim 2.

4. The external dimensions or circular diameter of the internal connection portion of at least one of the electrode connection terminals are greater than or equal to the external dimensions or circular diameter of the electrode surrounding the internal connection portion. A capacitance device according to any one of claims 1 to 3.

5. The plurality of capacitance elements include capacitance elements whose external dimensions or circular diameters of the electrodes differ from each other. A capacitance device according to any one of claims 1 to 3.

6. The external dimensions or circular diameter of the internal connection portion of at least one of the electrode connection terminals are greater than or equal to the external dimensions or circular diameter of the external connection portion of at least one of the electrode connection terminals. A capacitance device according to any one of claims 1 to 3.

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