JP4025719B2 - Capacitor - Google Patents

Description

  The present invention relates to a capacitor.

  In order to reduce the impedance of a capacitor formed by mounting a capacitor element on a substrate, particularly an electrolytic capacitor, the equivalent series inductance (ESL) and the equivalent series resistance (ESR) are required to be small. As a technique for reducing ESR, for example, there is a technique described in Patent Document 1.

  In the electrolytic capacitor described in Patent Document 1, a through hole is formed in a substrate on which a capacitor element is mounted. A first electrode connected to the anode part of the capacitor element and a second electrode connected to the cathode part are provided on the surface of the substrate. A first external electrode paired with the first electrode and a second external electrode paired with the second electrode are formed on the back surface of the substrate.

  The first electrode and the second electrode and the corresponding first external electrode and second external electrode are electrically connected through a through hole formed in the substrate. Therefore, the anode part and the cathode part of the capacitor element are electrically connected to the first external electrode and the second external electrode provided on the back surface of the substrate through the through holes. In this case, the current path is shortened and the ESR is reduced.

  By the way, from the viewpoint of increasing the capacitance of the electrolytic capacitor, it is preferable to reduce the area occupied by the first electrode on the substrate surface and increase the area occupied by the second electrode. For this reason, in order to increase the area of the second electrode, the first electrode and the second electrode are generally juxtaposed in the longitudinal direction rather than in the lateral direction of the rectangular substrate.

In general, the first electrode and the second electrode on the front surface of the substrate and the first external electrode and the second external electrode on the back surface of the substrate are arranged in substantially the same pattern. Therefore, when the first electrode and the second electrode are juxtaposed in the longitudinal direction of the substrate as described above, the first external electrode and the second external electrode are also juxtaposed in the longitudinal direction.
JP 2001-102252 A

  However, in recent years, there has been an increasing demand for lower ESL of capacitors, particularly electrolytic capacitors. In the case where the first and second external electrodes are arranged in parallel in the longitudinal direction of the rectangular substrate as described above, such a request is required. It is becoming difficult to fully meet the requirements.

  An object of the present invention is to provide a capacitor having a large capacitance and capable of reducing ESL.

  In order to solve the above problems, a capacitor according to the present invention includes a capacitor element having an anode part and a cathode part, and a substrate having an element mounting area extending in one direction in which the capacitor element is mounted. The substrate includes a substrate body in which first and second conductive paths penetrating from the front surface to the back surface are formed, and a first electrode and a cathode provided in an element mounting region on the surface and connected to an anode portion A second electrode connected to the first portion, a first external electrode provided on the back surface and electrically connected to the first electrode through the first conductive path, and a second electrode through the second conductive path A first external electrode and a second external electrode electrically connected to each other, wherein the first electrode and the second electrode are arranged in parallel in the longitudinal direction of the element mounting region. Is a first connection region for connecting to wiring outside the system, and The first connection region and the second connection region extend in the longitudinal direction of the element mounting region and are arranged in parallel in a direction crossing the longitudinal direction. .

  In the above configuration, since the first electrode and the second electrode are arranged in parallel in the longitudinal direction of the element mounting region, the area occupied by the second electrode in the element mounting region is increased, and the first electrode is occupied. The area can be reduced. Thereby, since the area of the cathode part of the capacitor | condenser element mounted in a board | substrate can be enlarged, the electrostatic capacitance of a capacitor | condenser can be expanded.

  Furthermore, the first connection region and the second connection region extend in the longitudinal direction of the element mounting region and are arranged in parallel in a direction intersecting the longitudinal direction. Therefore, since the length of the first and second connection regions in the longitudinal direction can be further increased, the width of the current path is increased and ESL is reduced.

  In the capacitor according to the present invention, the region other than the first connection region in the first external electrode and the region other than the second connection region in the second external electrode are covered with an insulating material. Preferably it is.

  In this case, it is not connected to wiring outside the system except for the first connection region and the second connection region. For this reason, since current flows suitably in the shapes of the first connection region and the second connection region extending in the longitudinal direction of the element mounting region, ESL is likely to be reduced as described above.

  Furthermore, in the capacitor according to the present invention, a plurality of first conductive paths are arranged along the edge of the first electrode on the second electrode side, and the second conductive paths are in the second electrode. It is preferable that a plurality are arranged along the edge on the first electrode side.

  In this case, since the distance between the first and second conductive paths becomes shorter, ESL is likely to cancel out. Therefore, ESL tends to be reduced. Furthermore, since a plurality of first and second conductive paths are formed, ESL is more likely to be reduced.

  In the capacitor according to the present invention, the first conductive path and the second conductive path are formed between the first connection region and the second connection region, and the first external electrode is A first conductive region extending from the first connection region toward the second connection region so as to cover a region where the first conductive path is formed on the back surface; A second conductive region extending from the second connection region toward the first connection region so as to cover a region where the second conductive path is formed; the first conductive region and the second conductive region; Is preferably parallel to the longitudinal direction of the element mounting region. In this case, the direction of the current flowing through the first conduction region and the second conduction region is also reversed, so that ESL is easily reduced.

  In the capacitor according to the present invention, the area of the second electrode is preferably larger than the area of the first electrode. In this case, since the area of the second electrode is large, the area of the cathode portion of the capacitor element can be increased. Therefore, it is possible to increase the capacitance of the capacitor.

  ADVANTAGE OF THE INVENTION According to this invention, the capacitor | condenser with a large electrostatic capacitance and low ESL can be provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are used for the same elements, and duplicate descriptions are omitted.

  FIG. 1 is a schematic perspective view showing the capacitor of this embodiment. As shown in FIG. 1, the capacitor 1 includes a capacitor element 10 and a substrate 20 having an element mounting area α that is an area where the capacitor element 10 is mounted and extends in one direction. In the present embodiment, the capacitor 1 is an electrolytic capacitor. Further, since the substrate 20 has a substantially rectangular flake shape extending in one direction as shown in FIG. 1, the region defined by the outer periphery of the substrate 20 corresponds to the element mounting region α.

  In the present specification, the long side direction (longitudinal direction of the element mounting region) of the substrate 20 is described as the X direction, the short side direction is defined as the Y direction, and the direction orthogonal to the X direction and the Y direction is described as the Z direction.

  The capacitor element 10 includes an anode part 11 and a cathode part 12. The shape of the cathode portion 12 is a substantially rectangular thin piece extending in the X direction as shown in FIG. The anode portion 11 protrudes outward (−X direction) from the edge portion of the cathode portion 12 extending in the Y direction. An insulating portion 13 made of an insulating material is provided between the anode portion 11 and the cathode portion 12 in order to prevent short circuit between them.

  FIG. 2 is a schematic diagram showing a cross-sectional configuration of the capacitor element 10 along the line II-II in FIG.

  The anode part 11 is composed of a partial region of an aluminum substrate (valve metal substrate) 15 having a dielectric layer 14 formed on the surface layer. The dielectric layer 14 is an aluminum oxide film, and is formed by subjecting the aluminum substrate 15 to roughening (enlargement) by etching and then chemical conversion, that is, anodic oxidation.

  The cathode portion 12 includes an electrolyte layer 16 that covers a region of the aluminum substrate 15 excluding the anode portion 11, and a conductor layer 17 formed around the electrolyte layer 16.

  The electrolyte layer 16 includes a conductive polymer compound. The electrolyte layer 16 is formed by impregnating the material to be the electrolyte layer 16 in a monomer state in the concave portion of the roughened surface of the aluminum substrate 15 and then performing chemical oxidation polymerization or electrolytic oxidation polymerization. .

  The conductor layer 17 includes a graphite paste layer 18 and a silver paste layer 19 which are sequentially formed on the electrolyte layer 16 by any one of a screen printing method, a dipping method and a spray coating method, for example. In the capacitor element 10, the electrolyte layer 16 and the conductor layer 17 function as a cathode.

  Next, the substrate 20 on which the capacitor element 10 is mounted will be described with reference to FIGS. FIG. 3 is a schematic diagram showing a cross-sectional configuration of the capacitor 1 along the line III-III in FIG. FIG. 4A is a plan view of the front surface 31 side of the substrate 20. FIG. 4B is a plan view of the back surface 32 side of the substrate 20.

  The substrate 20 is made of an epoxy resin and has a substrate body 30 having a substantially rectangular flake shape. In this specification, the surface of the substrate body 30 on which the capacitor element 10 is mounted is referred to as a front surface 31, and the surface opposite to the front surface 31 is referred to as a back surface 32.

  The substrate 20 is a printed wiring board in which the first electrode 40A and the second electrode 40B made of copper are printed on the front surface 31, and the first outer electrode 50A and the second outer electrode 50B made of copper are printed on the back surface 32. is there.

  The first electrode 40 </ b> A is connected to the anode portion 11 of the capacitor element 10. The first electrode 40A and the first external electrode 50A are electrically connected through a through hole (first conductive path) 33A penetrating from the front surface 31 to the back surface 32 of the substrate body 30. The second electrode 40B is connected to the cathode portion 12 of the capacitor element 10. The second electrode 40B and the second external electrode 50B are electrically connected through a through hole (second conductive path) 33B penetrating from the front surface 31 to the back surface 32.

  As shown in FIGS. 3 and 4A, a plurality of through holes 33A are provided along the edge 41A in contact with the edge 41A on the second electrode 40B side of the first electrode 40A. Further, a plurality of through holes 33B are provided along the edge portion 41B in contact with the edge portion 41B on the first electrode 40A side of the second electrode 40B. In other words, the through holes 33A and 33B are located on both sides of the boundary between the first electrode 40A and the second electrode 40B, and are arranged in a plurality in the Y direction. The through holes 33A and 33B are configured by filling a hole penetrating from the front surface 31 to the back surface 32 with a conductive material.

  As shown in FIG. 4A, the first electrode 40A and the second electrode 40B are substantially rectangular and are juxtaposed in the longitudinal direction (X direction) of the substrate 20. The length in the X direction of the second electrode 40B is longer than the length in the X direction of the first electrode 40A, and the occupied area of the second electrode 40B on the surface 31 is larger than the occupied area of the first electrode 40A. ing.

  Further, the first electrode 40A and the second electrode 40B are insulating films 60 (shaded portions in FIG. 4A) made of an insulating material such as solder resist from the edge 41A to the edge 41B. It is covered. The insulating film 60 also enters (between) the first electrode 40A and the second electrode 40B. Thus, by providing the insulating film 60, when the capacitor element 10 is mounted on the substrate 20, the cathode portion 12 is short-circuited to the first electrode 40A, or the anode portion 11 is short-circuited to the second electrode 40B. Is prevented. The insulating film 60 has a width in the Y direction wider than the widths of the first and second electrodes 40A and 40B, and covers the surface 31 as well.

  As shown in FIG. 4B, the shape of the first external electrode 50A and the second external electrode 50B is substantially L-shaped. The first and second external electrodes 50A and 50B are arranged so as to fit each other. However, the first and second external electrodes 50A and 50B are isolated.

  The first and second external electrodes 50A and 50B have a rectangular insulating film 61 extending in the X direction including the boundary and the region covering the through holes 33A and 33B (FIG. 4B). It is covered with the hatched part in the middle. The insulating film 61 also enters (between) the first and second external electrodes 50A and 50B in order to more reliably electrically insulate the first and second external electrodes 50A and 50B. It is out. Further, the insulating film 61 is formed so that the width in the X direction is wider than the width of the first external electrodes 50A and 50B, and also covers the back surface 32.

  A region of the first external electrode 50A that is not covered with the insulating film 61, that is, an exposed region is connected to a wiring (for example, another circuit board) outside the system (that is, outside the capacitor 1). This is the first connection region 51A. In addition, a region of the second external electrode 50B that is not covered with the insulating film 61, that is, an exposed region is a second connection region 51B for connection to a wiring outside the system.

  The first connection region 51A is formed on one end 34 side of the pair of end portions 34, 35 extending in the X direction on the back surface 32, and extends in the X direction (longitudinal direction). The second connection region 51B is formed on the end portion 35 side that forms a pair with the end portion 34, and extends in the X direction. The first connection region 51 </ b> A and the second connection region 51 </ b> B are arranged in parallel in a direction substantially orthogonal to the longitudinal direction of the substrate 20. Further, the length of the first and second connection regions 51A and 51B in the X direction is substantially equal to the length of the substrate 20 in the X direction.

  In the first external electrode 50A, the region other than the first connection region 51A is a first conduction region 52A that is directly connected to the plurality of through holes 33A. The first conduction region 52A extends from the first connection region 51A toward the second connection region 51B so as to cover a region where the plurality of through holes 33A are formed on the back surface 32.

  In the second external electrode 50B, the region other than the second connection region 51B is a second conduction region 52B that is directly connected to the plurality of through holes 33B. The second conduction region 52B extends from the second connection region 51B toward the first connection region 51A so as to cover a region where the plurality of through holes 33B are formed on the back surface 32.

  As shown in FIG. 4B, the first conduction region 52A and the second conduction region 52B are arranged in parallel in the X direction and are covered with an insulating film 61.

  Next, a method for manufacturing the capacitor 1 of FIG. 1 by mounting the capacitor element 10 on the substrate 20 will be described. First, the capacitor element 10 is mounted on the substrate 20 so that the anode portion 11 of the capacitor element 10 is in contact with the first electrode 40A and the cathode portion 12 is in contact with the second electrode 40B.

  Next, the cathode part 12 and the second electrode 40B are connected using, for example, a conductive adhesive. Thereby, the cathode part 12 and the 2nd electrode 40B are electrically connected. Since the second electrode 40B is electrically connected to the second external electrode 50B through the through hole 33B, the cathode portion 12 and the second external electrode 50B are electrically connected.

  Subsequently, the anode part 11 and the first electrode 40A are connected by metal welding means such as YAG laser spot welding. Thereby, the aluminum base 15 constituting the anode part 11 and the first electrode 40A are electrically connected. Since the first electrode 40A is electrically connected to the first external electrode 50A through the through hole 33A, the aluminum base 15 and the first external electrode 50A are electrically connected.

  Therefore, it is possible to charge and discharge the capacitor element 10 by connecting wiring outside the system to the first connection region 51A and the second connection region 51B.

  Further, since the first electrode 40A and the second electrode 40B are arranged in parallel in the longitudinal direction of the substrate 20, the capacitor element 10 in which the anode portion 11 and the cathode portion 12 are arranged in the same manner (see FIG. 1). Can be suitably mounted.

  By the way, as shown in the comparative example of FIG. 5A (not the embodiment of the present invention), the substrate 80 in which the first and second electrodes 70A and 70B are arranged in parallel in the Y direction is shown in FIG. The capacitor element 90 shown in b) is preferably mounted. That is, the capacitor element 90 in which the anode portion 91 and the cathode portion 92 are arranged in a direction substantially orthogonal to the longitudinal direction of the substrate 20 is mounted.

  When the length of the anode part protruding from the cathode part is constant, the anode part 11 and the cathode part 12 are arranged in the longitudinal direction of the capacitor element 10 as shown in FIG. ), The area of the cathode part can be made larger than when the anode part 91 and the cathode part 92 are arranged in a direction orthogonal to the longitudinal direction of the capacitor element 90. Therefore, the capacitance of the capacitor element 10 is larger than that of the capacitor element 90. Therefore, the capacitance of the capacitor 1 can be increased by using the substrate 20 of the present embodiment.

  Next, operations and effects based on the formation of the first connection region 51A and the second connection region 51B will be described.

  Usually, the first external electrode and the second external electrode are formed corresponding to the arrangement pattern of the first electrode 40A and the second electrode 40B on the surface 31. Therefore, as described above, when the first electrode 40A and the second electrode 40B are arranged in parallel in the longitudinal direction in order to increase the capacitance, conventionally, the first external electrode and the second external electrode are also provided. They were juxtaposed in the longitudinal direction.

  In the case of such an arrangement pattern, the length of the first external electrode and the second external electrode is limited by the length in the short side direction of the substrate.

  On the other hand, in the present embodiment, the lengths of the first and second connection regions 51A and 51B are substantially the length in the longitudinal direction of the substrate 20. In this way, the width of the current path can be made wider than before, so that ESR and ESL can be further reduced.

  Further, since the through holes 33A and 33B are provided below the edge portions 41A and 41B, they are close to each other. As a result, the ESL is more likely to be canceled out, and the ESL tends to be further reduced. From the viewpoint of reducing ESL, the through hole 33A and the through hole 33B are preferably juxtaposed in a direction (X direction) substantially orthogonal to the edge portion 41A (or the edge portion 41B).

  Furthermore, since the first conduction region 52A and the second conduction region 52B are formed as described above, the directions of the currents flowing through the first conduction region 52A and the second conduction region 52B are also reversed. Therefore, ESL is likely to be reduced.

  As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to the said embodiment. For example, although an aluminum substrate is used as the valve metal substrate, it may be a substrate composed of a valve metal such as tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony.

  Further, the through holes 33A and 33B are configured such that the hole portion penetrating from the front surface 31 to the back surface 32 is filled with the conductive material. For example, only the inner wall surface of the hole portion is made of the conductive material made of the conductive material. A layer may be formed. Further, although the plurality of through holes 33A and 33B are formed on both sides of the boundary between the first and second electrodes 40A and 40B, the present invention is not limited to this. If the through hole 33A electrically connects the first electrode 40A and the first external electrode 50A, and the through hole 33B electrically connects the second electrode 40B and the second external electrode 50B Good. However, as described above, the arrangement of the embodiment (see FIG. 4A) is preferable from the viewpoint of further reducing ESL.

  Further, the first external electrode 50A and the second external electrode 50B are not necessarily L-shaped. The first external electrode 50A will be described. The length (width) in the X direction of the first conduction region 52A is long enough to cover the plurality of through holes 33A, and the first connection region 51A extends from the first connection region 51A. The convex shape may extend toward the second connection region 51B. The same applies to the second external electrode 50B. When the width of the first conductive region 52A is sufficient to cover the through hole 33A and the width of the second conductive region 52B is sufficient to cover the through hole 33B, the first and second connection regions 51A, In order to form 51B, the insulating film 61 may not cover the first and second external electrodes 50A and 50B.

  Furthermore, although the board | substrate 20 was made into the substantially rectangular thin piece shape, the shape of the board | substrate 20 is not specifically limited. What is necessary is just to have the element mounting area | region which is an area | region where the capacitor | condenser element 10 is mounted, and is extended in one direction. When the shape of the substrate (that is, the substrate body) is not a substantially rectangular flake, the first and second conductive paths are formed in the element mounting region in the substrate body, and the first and second electrodes are provided. Just do it.

  Moreover, the anode part 11 and the cathode part 12 in the capacitor | condenser element 10 are not restricted to a form as shown in FIGS. For example, a lead or the like may be drawn from the substantially rectangular thin piece of cathode portion 12, and the cathode portion 12 and the lead may be used as one cathode portion. The same applies to the anode part 11.

  The capacitor 1 is preferably an electrolytic capacitor, but is not limited to an electrolytic capacitor, and may be any capacitor that is used by being mounted in an element mounting region extending in one direction.

It is a schematic perspective view of the capacitor according to the present embodiment. It is a schematic diagram which shows the cross-sectional structure of the capacitor | condenser element along the II-II line | wire in FIG. It is a schematic diagram which shows the cross-sectional structure of the capacitor | condenser along the III-III line in FIG. FIG. 4A is a plan view of the surface side of the substrate. FIG. 4B is a plan view of the back side of the substrate. FIG. 5A is a plan view of a substrate in which the first and second electrodes are arranged in a direction substantially orthogonal to the longitudinal direction of the substrate. FIG.5 (b) is a top view of the capacitor | condenser element mounted in the board | substrate shown to Fig.5 (a).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Capacitor, 10 ... Capacitor element, 11 ... Anode part, 12 ... Cathode part, 14 ... Dielectric layer, 15 ... Aluminum base | substrate (valve metal base | substrate), 16 ... Electrolyte layer, 17 ... Conductor layer, 20 ... Substrate, DESCRIPTION OF SYMBOLS 30 ... Board | substrate body, 31 ... Front surface, 32 ... Back surface, 33A ... Through hole (1st conductive path), 33B ... Through hole (2nd conductive path), 50A ... 1st external electrode, 50B ... 2nd External electrode, 51A, first connection region, 51B, second connection region, α, element mounting region.

Claims (5)

A capacitor element having an anode part and a cathode part;
A substrate having an element mounting region that extends in one direction in which the capacitor element is mounted;
The substrate is
A substrate body formed with first and second conductive paths penetrating from the front surface to the back surface;
A first electrode connected to the anode part and a second electrode connected to the cathode part, provided in the element mounting region on the surface;
A first external electrode provided on the back surface and electrically connected to the first electrode through the first conductive path and electrically connected to the second electrode through the second conductive path A second external electrode;
The first electrode and the second electrode are arranged in parallel in the longitudinal direction of the element mounting region,
The first external electrode and the second external electrode have a first connection region and a second connection region for connecting to a wiring outside the system,
The capacitor is characterized in that the first connection region and the second connection region extend in the longitudinal direction of the element mounting region and are arranged in parallel in a direction crossing the longitudinal direction.   A region other than the first connection region in the first external electrode and a region other than the second connection region in the second external electrode are covered with an insulating material. The capacitor according to claim 1.   A plurality of the first conductive paths are arranged along an edge of the first electrode on the second electrode side, and the second conductive path is the first electrode of the second electrode. The capacitor according to claim 1, wherein a plurality of the capacitors are arranged along a side edge. The first conductive path and the second conductive path are formed between the first connection region and the second connection region,
The first external electrode includes a first conduction region extending from the first connection region toward the second connection region so as to cover a region of the back surface where the first conductive path is formed. Have
The second external electrode has a second conduction region extending from the second connection region toward the first connection region so as to cover a region of the back surface where the second conductive path is formed. Have
4. The capacitor according to claim 1, wherein the first conduction region and the second conduction region are arranged in parallel in a longitudinal direction of the element mounting region.   5. The capacitor according to claim 1, wherein an area of the second electrode is larger than an area of the first electrode.

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