JP5445737B2 - Solid electrolytic capacitor - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor, and more particularly to a solid electrolytic capacitor having a low equivalent series inductance as electrical characteristics and good transient response characteristics.

  Along with the increase in frequency of electronic equipment, capacitors that are one of the electronic components have been required to have better impedance characteristics in the high frequency range than before. Various solid electrolytic capacitors using a highly conductive polymer as a solid electrolyte have been studied.

  In recent years, a solid electrolytic capacitor used around a CPU of a personal computer has been strongly demanded to have a small size and a large capacity. Further, not only a low ESR (equivalent series resistance) is reduced in response to a higher frequency but also a noise. There is a strong demand for low ESL (equivalent series inductance) excellent in removal and transient response, and various studies have been made to meet such demand.

  Generally, as a method for reducing the ESL, firstly, the current path is made as short as possible, and secondly, the magnetic field formed by the current path is canceled by the magnetic field formed by another current path. A third method is known in which the current path is divided into n and the effective ESL is reduced to 1 / n.

  For example, the invention disclosed in Japanese Patent Laid-Open No. 2000-311832 employs the first and third methods, and the invention disclosed in Japanese Patent Laid-Open No. 06-267802 discloses the second and third methods. The invention disclosed in Japanese Patent Application Laid-Open No. 06-267801, Japanese Patent Application Laid-Open No. 11-288846, and Japanese Patent No. 4208831 employs the third method.

JP 2000-311832 A JP 06-267802 A JP 06-267801 A JP-A-11-288846 Japanese Patent No. 4208831

  Among the above-mentioned documents, the capacitor disclosed in Patent Document 1 can cope with high frequency by using a thin film capacitor, but in order to increase the capacitance, is it necessary to increase the area of the dielectric layer? It is necessary to laminate dielectric layers. The dielectric layer used is a perovskite-type complex oxide crystal containing Ba and Ti, and the realizable capacitance is nanofarad (nF) order capacitance, and microfarad (μF). There is a disadvantage that it is difficult to adopt when a capacitance of the order is required.

  Further, in the solid electrolytic capacitors disclosed in Patent Document 2 and Patent Document 4, the current path is divided by making the solid electrolytic capacitor into four terminals, so that the solid electrolytic capacitor is more than the conventional two-terminal type solid electrolytic capacitor. To reduce ESL. However, Patent Document 2 has a structure in which an external anode terminal portion and an external cathode terminal portion are attached to a capacitor element, and the current path inside the solid electrolytic capacitor is not always short.

  Further, in the solid electrolytic capacitor disclosed in Patent Document 4, the anode and cathode terminals are arranged on the four side surfaces of the solid electrolytic capacitor, and the external electrodes are separated from each other. Can't expect.

  In the solid electrolytic capacitor described in Patent Document 3, a plurality of metal substrate portions positioned between the capacitor portions and the capacitor portions are bent in a zigzag shape in opposite directions, and the capacitor portions are joined to each other and laminated. Since the metal substrates located at both ends of the capacitor portion of the solid capacitor unit plate are joined so that all the metal substrates are connected in series, the bent metal substrate portions or the metal substrate portions joined to each other act as a coil and are laminated. The solid electrolytic capacitor is configured as a kind of filter circuit. Then, by covering the periphery of the bent metal substrate portion or the metal substrate portions joined to each other with a magnetic material, this multilayer solid electrolytic capacitor is configured as an effective filter device by combining a capacitor and a coil. Although it has been shown that it can be used as a noise absorbing device in a high frequency region, since a lead frame is used as a current path from the capacitor element inside the solid electrolytic capacitor to the external electrode, There is a problem that the current path inside the electrolytic capacitor becomes redundant and the ESL reduction effect is not sufficient.

  In the solid electrolytic capacitor disclosed in Patent Document 5, a pseudo 5-terminal type solid electrolytic capacitor is adopted, and the current path of the anode is divided into four to reduce the effective ESL. However, since the lead frame is used as a current path from the capacitor element inside the solid electrolytic capacitor to the external electrode, the current path inside the solid electrolytic capacitor becomes redundant, and the ESL reduction effect is not sufficient. I have a problem.

  As described above, although the solid electrolytic capacitor described in the above-mentioned document has an effect of reducing ESL as compared with a conventionally known two-terminal capacitor, it does not always meet the demand for low ESL that has been required in recent years. A sufficient effect was not obtained.

  The present invention provides a structure for further reducing ESL of a solid electrolytic capacitor by using a solid electrolytic capacitor that can easily increase the capacitance.

  Accordingly, an invention according to claim 1 of the present application is directed to a solid electrolytic capacitor including a capacitor element in which a dielectric layer, a solid electrolyte layer, and a cathode lead portion are sequentially formed on an anode body having an anode lead portion. A first cathode terminal portion is disposed at the center of the mounting surface facing the substrate, an anode terminal portion is disposed around the first cathode terminal portion, and a second cathode terminal is disposed adjacent to the anode terminal portion. The solid electrolytic capacitor is characterized in that the portion is arranged.

  The invention according to claim 2 of the present application includes a capacitor element in which a dielectric layer, a solid electrolyte layer, and a cathode lead part are sequentially formed on an anode body having an anode lead part, and the capacitor element is mounted. And a mounting surface facing the wiring board, and on the surface on which the capacitor element is mounted, conductors respectively corresponding to the anode lead portion and the cathode lead portion of the capacitor element are formed. Comprises a mounting substrate in which an anode terminal portion and a cathode terminal portion are formed, and the conductor penetrates through the interior and is electrically connected to the anode terminal and the cathode terminal, respectively, on the mounting surface of the mounting substrate. The first cathode terminal portion is disposed at the center of the mounting substrate, the anode terminal portion is disposed on the four sides of the mounting substrate so as to surround the outer periphery of the first cathode terminal portion, and the four corners of the mounting substrate are provided. The anode terminal And the adjacent position to a solid electrolytic capacitor, characterized in that arranged a second cathode.

  Furthermore, in the invention according to claim 3, in the solid electrolytic capacitor according to claim 1 or 2, the first cathode terminal portion arranged at the center of the mounting surface is larger than the cathode lead portion of the capacitor element. And a region larger than the anode terminal portion and the second cathode terminal portion.

  In the invention according to claim 4 of this application, in the solid electrolytic capacitor according to any one of claims 1 to 3, the first cathode terminal portion is a central portion of the mounting surface, and It is arranged in a region close to the anode terminal portion, and the central portion is an insulating region.

  According to the first aspect of the present invention, in a solid electrolytic capacitor comprising a capacitor element in which a dielectric layer, a solid electrolyte layer, and a cathode lead-out portion are sequentially formed on an anode body having an anode lead-out portion, facing the wiring board. A first cathode terminal portion is disposed at the center of the mounting surface, an anode terminal portion is disposed around the first cathode terminal portion, and a second cathode terminal portion is disposed at a position adjacent to the anode terminal portion. Thus, first, the distance from the anode lead portion and the cathode lead portion of the capacitor element to the anode terminal portion and the cathode terminal portion of the mounting board, which is the current outlet, is achieved by a distance corresponding to the thickness of the mounting board. Therefore, the current path can be shortened. Secondly, since the anode terminal portion of the mounting substrate is arranged so that the three directions are surrounded by the cathode terminal portion, the effect of canceling the induced magnetic fields of the anode and the cathode is large, and the ESL of the solid electrolytic capacitor can be reduced. .

  According to the second aspect of the present invention, as the mounting substrate for the solid electrolytic capacitor, the anode lead portion and the cathode conductor corresponding to the anode lead portion and the cathode lead portion of the capacitor element are formed on the surface on which the capacitor element is to be mounted. The mounting surface of the substrate has a first cathode terminal portion at the center of the mounting substrate, and four anode terminal portions on the four sides of the mounting substrate so as to surround the outer periphery of the first cathode terminal portion. The four corners have second cathode terminal portions electrically connected to the cathode lead portion of the capacitor element. Since the second cathode terminal portion is disposed adjacent to the anode terminal portion, the anode terminal portion is surrounded in three directions by the first cathode terminal portion and the second cathode terminal portion, respectively. Arrangement. And, by the configuration in which the anode conductor and the anode terminal portion, and the cathode conductor and the cathode terminal portion are electrically connected by conductors penetrating the mounting substrate, respectively, first, from the anode lead portion and the cathode lead portion of the capacitor element, The distance to the anode terminal portion and the cathode terminal portion of the mounting substrate, which is the current outlet, can be achieved by a distance corresponding to the thickness of the mounting substrate, and the current path can be shortened. Second, since the anode terminal portion of the mounting substrate is arranged so that three directions are surrounded by the cathode terminal portion, the effect of canceling the induced magnetic fields of the anode and the cathode is large. Third, by forming the anode terminal portion at four locations, the current path can be divided into four, and the substantial ESL can be reduced to ¼.

  That is, in the solid electrolytic capacitor of the present invention, a method of shortening the length of the current path as the first element technology for reducing ESL and a magnetic field formed by the current path as the second element technique are separated. Using all the methods of canceling by the magnetic field formed by the current path of the current, and dividing the current path, which is the third elemental technology, into n pieces and reducing the effective ESL to 1 / n, Thus, it is possible to realize a solid electrolytic capacitor with an increased reduction effect.

  According to the invention of claim 3, the first cathode terminal portion disposed in the center of the mounting surface is formed in a region substantially equal to the size of the cathode lead portion of the capacitor element, and the anode terminal portion and the second cathode Since the area is larger than the terminal portion, the distance from the cathode lead portion of the capacitor element to the first cathode terminal portion can be formed to be the shortest, and ESL can be reduced, and the capacitor element can be reduced. The current capacity output from the cathode lead-out portion can be increased, and the cathode terminal portion can supply a large current during a transient response.

  According to the invention of claim 4, the first cathode terminal portion is disposed in a central portion of the mounting surface and in the vicinity of each anode terminal portion, and the central portion is an insulating region. As the current path of the cathode terminal portion of 1 is narrowed, the current is concentrated, and the effect of canceling the induced magnetic field can be further enhanced by bringing the current path close to the anode terminal portion. That is, it is possible to realize a solid electrolytic capacitor that further enhances the overall ESL reduction effect.

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows the 1st shape of the capacitor | condenser element piece used for the solid electrolytic capacitor of this invention, (a), (b) is sectional drawing, (c) is a top view. It is the perspective view which shows the shape of the 1st capacitor | condenser element piece used for the solid electrolytic capacitor of this invention and a capacitor | condenser element, (a)) shows a capacitor | condenser element piece, (b) shows a capacitor | condenser element. It is drawing which shows the 2nd shape of the capacitor | condenser element piece used for the solid electrolytic capacitor of this invention, (a), (b) is sectional drawing, (c) is a top view. It is a perspective view which shows the shape of the 2nd capacitor | condenser element piece used for the solid electrolytic capacitor of this invention and a capacitor | condenser element, (a) shows a capacitor | condenser element piece, (b) shows a capacitor | condenser element. It is drawing which shows the 3rd shape of the capacitor | condenser element used for the solid electrolytic capacitor of this invention, (a), (b) is sectional drawing, (c) is a top view. It is drawing which shows the shape of the mounting substrate used for the solid electrolytic capacitor of this invention, (a) is a drawing which shows the mounting surface of a capacitor | condenser element, (b) is a mounting surface. It is sectional drawing of the mounting substrate used for the solid electrolytic capacitor of this invention. It is drawing which shows the solid electrolytic capacitor of this invention, (a) is a top view, (b) is sectional drawing. It is drawing which shows another Example of the mounting substrate used for the solid electrolytic capacitor of this invention, (a) is a surface which mounts a capacitor | condenser element, (b) is drawing which shows a mounting surface.

  Next, embodiments for carrying out the present invention will be described in detail. The solid electrolytic capacitor of the present invention includes a capacitor element and a mounting substrate on which the capacitor element is mounted.

  The shape of the capacitor element is not particularly limited, but a capacitor element having a cathode extraction part at the center part and having anode extraction parts arranged in four radial directions from the cathode extraction part and having a cross-shaped shape as viewed from above is suitable. It is. The reason is that the capacitor element can obtain more capacitance as the surface area of the dielectric layer serving as the capacitance forming portion is larger. Therefore, it is preferable to increase the ratio of the area of the capacitance forming portion to the area of the mounting substrate. And since an anode drawer part does not contribute to the increase in this electrostatic capacitance, it is preferable that the area | region of an anode drawer part is small. On the other hand, since the anode lead portion serves as a current path, it is desirable that the cross-sectional area of the anode lead portion is large in order to flow a large current for dealing with a transient response. From such a viewpoint, by forming the anode lead portion with the same width as the capacity forming portion, the cross-sectional area of the anode lead portion can be increased. On the other hand, in order to reduce ESL by forming anode terminal portions at a plurality of locations and dividing the current path, it is preferable to use a capacitor element having a multi-terminal structure. By disposing the anode terminal portion in the direction, a capacitor element having anode terminal portions at four locations can be realized. For this reason, it is preferable to have a capacity forming portion in the center, and to arrange anode terminal portions in four radial directions from the capacity forming portion with a width substantially the same as this capacity forming portion. The capacitor element has a cross shape. And in the top view shape, the cathode lead portion occupies a larger area than each of the anode lead portions formed at four places, which is an effective means for producing a solid electrolytic capacitor having an increased capacitance. Become.

First, a capacitor element used for the solid electrolytic capacitor of the present invention will be described. As the capacitor element, the following three forms are suitable.
(1) A rectangular capacitor element piece with one end portion serving as an anode lead portion and the other end portion serving as a cathode lead portion is overlapped so that the orientation of the anode lead portion is a perpendicular rotation angle. In addition, a configuration in which the central portion is a cathode extraction portion and anode extraction portions are formed in four directions from the cathode extraction portion.
(2) A rectangular capacitor element piece in which both ends are an anode lead portion and a central portion between the anode lead portions is a cathode lead portion, the cathode lead portions overlap with each other, and the mutual anode lead portions have a right angle of rotation. In this configuration, the capacitor element pieces are stacked so as to be oriented in the direction, the central part is a cathode lead part, and the anode lead part is formed in four directions from the cathode lead part.
(3) A form in which a cathode lead portion is formed at the center of the cross-shaped anode body and the end portion is an anode lead portion.

  First, the capacitor element of the first embodiment described in the above (1) will be described below. As shown in FIG. 1, the capacitor element piece 11 is made of a substantially rectangular valve metal plate or valve metal foil (hereinafter referred to as an anode body) such as aluminum, and one end of the anode body is expanded by etching. Surface treatment is performed (FIG. 1A), and a porous etching layer 15 is formed on both surfaces of the anode body. The unetched portion at the other end of the anode body becomes the anode lead portion 12 of the capacitor element piece 11. During the etching process, the inside of the anode body is not etched and an aluminum ingot remains, and this aluminum ingot becomes a remaining core layer. Next, a dielectric oxide film to be a dielectric layer is formed on the surface of the etching layer 15 by anodic oxidation.

  More specifically, the etching treatment is a step of forming a porous etching layer by dissolving both surfaces of the anode body with hydrochloric acid or the like. For example, using an anode body made of a high-purity aluminum foil having a cross-sectional size of 7.5 mm × 5 mm and a thickness of 120 μm, an etching layer is formed at a depth of 40 μm from both sides from one end of the anode body to a position of 6 mm. Form. In this case, the thickness of the remaining core layer is 40 μm. The etched anode body is subjected to chemical conversion treatment by anodic oxidation to form a dielectric oxide film layer made of aluminum oxide. Anodization is to form a dielectric oxide film by applying a predetermined voltage while the etching foil is immersed in an aqueous solution such as boric acid or adipic acid.

  A separation layer 14 is formed on the capacitor element piece, and the anode lead portion 12 and the cathode lead portion 13 of the capacitor element piece 11 are divided. After the etching process is completed, the separation layer 14 is coated with an insulating resin and penetrated into the etching layer 15 to insulate the anode lead portion 12 and the etching layer 15. For example, the separation layer 14 can be formed to a position of 0.5 mm from the unetched portion.

  Further, a solid electrolyte layer (not shown) is formed on the dielectric oxide film. The solid electrolyte layer is sequentially immersed in a solution containing a polymerizable monomer that becomes a conductive polymer by polymerization and an oxidizer solution, and is pulled up from each solution to advance the polymerization reaction. These solid electrolyte layers may be formed by a method of applying or discharging a solution containing a polymerizable monomer and an oxidant solution. Moreover, the method of immersing and apply | coating to the mixed solution which mixed the polymerizable monomer solution and the oxidizing agent may be used.

  Further, the solid electrolyte layer can also be formed by an electrolytic polymerization method used in the field of solid electrolytic capacitors or a method of applying and drying a conductive polymer solution. Furthermore, it is also possible to form a solid electrolyte layer by combining these solid electrolyte layer forming methods.

  As described above, thiophene, pyrrole or their derivatives can be suitably used as the polymerizable monomer used for forming the solid electrolyte layer. In particular, the monomer is preferably thiophene or a derivative thereof.

  Examples of thiophene derivatives can be exemplified by the following structures: thiophene or its derivatives have higher electrical conductivity and particularly excellent thermal stability than polypyrrole or polyaniline. An excellent solid electrolytic capacitor can be obtained.

X is O or S
When X is O, A is alkylene, or when at least one of polyoxyalkylene X is S,
A is alkylene, polyoxyalkylene, substituted alkylene, substituted polyoxyalkylene: wherein the substituent is an alkyl group, alkenyl group, alkoxy group

  Among the thiophene derivatives, 3,4-ethylenedioxythiophene is preferably used.

  As the oxidizing agent used for the polymerization of the polymerizable monomer, an aqueous solution of ferric paratoluenesulfonate, periodic acid or iodic acid dissolved in ethanol can be used.

  Further, as shown in FIG. 1B, a graphite layer and a silver paste layer are sequentially formed on the solid electrolyte layer of the capacitor element piece to form a cathode lead portion 13.

  Four pieces of capacitor element pieces 11 (FIGS. 1 (c) and 2 (a)) formed as described above are prepared, the cathode lead portion 13 overlaps, and the anode lead portion 12 has a right angle (90 degrees). By laminating so as to be shifted by an angle, the central portion becomes the cathode lead portion 13, and the anode lead portion 11 is arranged in four radial directions from the cathode lead portion 13 to form a cross-shaped capacitor element 10. (FIG. 2B). In this case, the cathode lead portions 13 of the capacitor element pieces 11 can be joined to each other by a conductive adhesive such as silver paste. The stacking of the capacitor element pieces 11 does not need to be sequentially shifted at a right angle, and the second capacitor element piece 11 is rotated on the first capacitor element piece 11 at a rotation angle of 180 degrees. It is also possible to stack the third capacitor element at a right angle (90 degrees) and stack the fourth capacitor element piece 11 at a rotation angle of 270 degrees. The order of laminating 11 is arbitrary.

  In such a capacitor element 10, when the anode body having the above-described cross-sectional size is used, the cathode lead-out portion 13 is 5 mm × 5 mm, and the anode lead-out portion 12 arranged radially in four directions from the cathode lead-out portion 13. The capacitor element 10 has a length of 1.5 mm.

Next, the form of the second capacitor element described in (2) will be described.
As shown in FIGS. 3 and 4, the capacitor element piece 21 uses a substantially rectangular valve metal plate or valve metal foil (hereinafter referred to as an anode body) such as aluminum, and the central portion of the anode body is expanded by etching. Surface treatment is performed to form a porous etching layer on both sides of the anode body (FIG. 3A). The unetched portions at both ends of the anode body become the anode lead portions 22 of the capacitor element pieces 21. At this time, the inside of the anode body is not etched and the aluminum ingot remains, and this aluminum ingot becomes the remaining core layer. In the same manner as the first capacitor element, a dielectric oxide film serving as a dielectric layer is formed on the etching layer 25, and a cathode lead portion 23 comprising a solid electrolyte layer, a graphite layer, and a silver paste layer is sequentially formed. (FIG. 3B, FIG. 4A). The capacitor element pieces 21 formed as described above are laminated so that the cathode lead portions 23 overlap and the anode lead portions 22 and 22 form a right angle to each other, so that the cathode lead portion 23 is formed at the center portion. A capacitor element 20 having a cross shape in top view in which the anode lead portion 22 is arranged in the four radial directions from the cathode lead portion 23 is created (FIG. 4B).

Finally, the form of the third capacitor element described in (3) will be described.
As shown in FIG. 5 (c), the capacitor element 30 has a valve metal foil or valve metal plate made of aluminum or the like formed in a cross shape in advance to form an anode body, and an end protruding in four directions is an anode lead part 32. And the central part is formed as the cathode lead-out part 33. As shown in FIGS. 5A and 5B, the manufacturing method from the formation of the etching layer 35 to the formation of the cathode extraction portion 33 until the formation of the cathode extraction portion 33 is the same as the method described above.

  Next, a capacitor element mounting substrate used in the present invention will be described with reference to FIGS. The mounting substrate 41 is based on an insulating substrate such as a rectangular glass epoxy substrate, and includes an anode terminal portion 42 and a first cathode terminal portion 43 on a mounting surface that faces a wiring substrate on which a solid electrolytic capacitor is mounted, The surface on which the capacitor element is mounted includes an anode conductor 44 and a cathode conductor 45 connected to the anode lead portion and the cathode lead portion of the capacitor element, respectively, and the anode conductor 46 and the anode terminal portion 44 and the cathode conductor on each surface. 45 and the first cathode terminal portion 43 are electrically connected.

  More specifically, as shown in FIG. 6 (a), a cathode conductor 45 joined to the cathode lead portion of the capacitor element is formed in a square shape at the center of the surface of the mounting substrate 41 on which the capacitor element is mounted. The four anode conductors 44 are arranged on the four sides of the mounting substrate 41 so as to surround the outer periphery of the cathode conductor 45. In addition, auxiliary conductors 47 that are electrically continuous with the cathode conductor 45 are disposed at the four corners of the mounting substrate 41. On the other hand, as shown in FIG. 6B, the mounting surface of the mounting substrate 41 is formed with a first cathode terminal portion 43 having substantially the same size as that of the anode conductor 44 at the center. The four anode terminal portions 42 are arranged so as to surround the outer periphery of the first cathode terminal portion 43. Then, second cathode terminal portions 46 are arranged at four corners of the mounting surface of the mounting substrate 41 so as to be adjacent to the anode terminal portion 42. As shown in FIG. 7, the anode conductor 44 and the anode terminal portion 42, the cathode conductor 45 and the first cathode terminal portion 43, the auxiliary conductor 47 and the second cathode terminal portion 46 formed on both surfaces of the mounting substrate 41 are These are electrically connected to each other through conductors 48 penetrating front and back such as via holes or through holes formed substantially perpendicular to the substrate surface of the mounting substrate 41.

  The anode conductor 44 and the cathode conductor 45 arranged on the surface of the mounting substrate 41 on which the capacitor element is mounted are conductors respectively corresponding to the anode lead portion and the cathode lead portion of the capacitor element, and match the shape of the capacitor element. It becomes the size and arrangement which can be mounted. When a capacitor element having a cross-sectional shape suitable for the shape of the capacitor element as described above is used, the cathode conductor 45 corresponding to the cathode lead portion of the capacitor element is a conductor formed on the mounting substrate 41. Will occupy the largest area. Further, if the first cathode terminal portion 43 connected to the cathode conductor 45 through a through hole or the like is also formed so as to occupy the same area as the cathode conductor 45, the cathode conductor 45, The first cathode terminal portion 43 is arranged at the shortest distance through the through hole, and it is possible to shorten the current path that is an element of ESL reduction. Therefore, the area occupied by the first cathode terminal portion 43 is the largest on the mounting surface of the mounting substrate 41 as compared with the anode terminal portion 42 and the second cathode terminal portion 46. Further, increasing the area occupied by the first cathode terminal portion 43 is also increasing the current capacity, and it is possible to flow a large current when outputting the charge accumulated by the capacitor element. By supplying the electric charge required at the time of the transient response with a large current, it is possible to quickly recover the instantaneous voltage drop state.

  An insulating substrate serving as a base for such a mounting substrate is preferably about 200 μm thick in terms of strength, but can also be about 80 μm thick. The anode terminal portion, the first cathode terminal portion, the second cathode terminal portion, and the conductor formed on the insulating substrate need only have low electrical resistance and can be soldered. It is preferable to use a conductor plated with gold. These electrodes and conductors can be formed with a thickness of 3 to 5 μm on one side. Further, the anode terminal portion of the mounting substrate 41, the cathode terminal portion and the conductor, and the through hole for electrically joining them can be formed by a method for producing a double-sided wiring substrate that is often used in a printed wiring board. it can. The arrangement of the through holes, the inner diameter, etc. at this time can be arbitrarily set.

  Note that the first cathode terminal portion 43 and the second cathode terminal portion 46 are preferably insulated by a resist layer on the mounting surface of the mounting substrate 41. When the conductive pattern connecting the first cathode terminal portion 43 and the second cathode terminal portion 46 is exposed on the mounting surface of the mounting substrate 41, the first cathode terminal portion 43 and the second cathode terminal portion The distance between the conductive pattern for connecting 46 and the anode terminal portion 42 becomes short, and a solder bridge is generated when soldering on the mounting surface, which may cause a short circuit. Therefore, when a conductive pattern for connecting the first cathode terminal portion 43 and the second cathode terminal portion 46 is formed on the mounting surface of the mounting substrate 41, it is preferable that at least the conductive pattern is covered with a resist layer. .

  Further, in order to electrically connect the first cathode terminal portion 43 and the second cathode terminal portion 46, the cathode conductor 45 and the auxiliary conductor 47 are electrically connected to the surface of the mounting substrate 41 on which the capacitor element is mounted. It is most preferable that the auxiliary conductor 47 and the second cathode terminal portion 46 are connected by a through hole or the like. Regardless of whether the conductive pattern is formed on the surface on which the capacitor element is mounted or the mounting surface, the characteristics of the solid electrolytic capacitor are not greatly affected. However, if a conductive pattern is formed on the mounting surface, this solid This is because there is a possibility that noise is generated due to electromagnetic coupling with a conductive pattern formed on a wiring board on which an electrolytic capacitor is mounted.

  In addition, the anode terminal portion 42 and the second cathode terminal portion 46 of the mounting substrate 41 are preferably formed up to the end of the mounting surface of the mounting substrate 41. If the anode terminal portion 42 and the second cathode terminal portion 46 are formed up to the end of the mounting surface of the mounting substrate 41, when the solid electrolytic capacitor is mounted on the wiring substrate or the like by soldering, the wiring substrate or the like A solder fillet is formed between the conductive pattern, the anode terminal portion 42, and the second cathode terminal portion 46, and visibility of whether or not the soldering connection is surely made is improved. Furthermore, when the anode terminal portion 42 and the second cathode terminal portion 46 are formed from the mounting surface to the side surface of the mounting substrate 41, it is preferable that the solder fillet is formed large.

  In such a mounting substrate, first, the distance from the anode lead portion and the cathode lead portion of the capacitor element to the anode terminal portion and the first cathode terminal portion of the mounting substrate, which is the outlet of current, is determined by the thickness of the mounting substrate. This can be achieved by a short distance, and the current path can be shortened. In particular, the thickness of the mounting substrate is preferably about 200 μm, but a thickness of about 80 μm can also be manufactured. Compared to the case where the capacitor element is attached to the lead frame and resin molded, the capacitor The distance from the cathode lead portion of the element to the first cathode terminal portion can be made extremely short. Second, since the anode terminal portion of the mounting substrate is arranged in three directions by the first cathode terminal portion and the second cathode terminal portion, the effect of canceling the induced magnetic fields of the anode and the cathode is large. Third, by forming the anode terminal portion at four locations, the current path can be divided into four, and the substantial ESL can be reduced to ¼.

  That is, in the solid electrolytic capacitor of the present invention, a method of shortening the length of the current path as the first element technology for reducing ESL and a magnetic field formed by the current path as the second element technique are separated. Using all the methods of canceling by the magnetic field formed by the current path of the current, and dividing the current path, which is the third elemental technology, into n pieces and reducing the effective ESL to 1 / n, This enhances the effect of reducing the above.

  Furthermore, the second cathode terminal portion equivalent in potential to the first cathode terminal portion is formed at the four corners of the mounting surface of the mounting substrate 41, so that the degree of freedom of conduction with the GND line such as the wiring substrate to be mounted is increased. Can also be increased. Further, in the conventional solid electrolytic capacitor having a five-terminal structure, it is difficult to visually confirm whether the first cathode terminal portion is securely soldered, but the second cathode terminal portion 46 is formed at the four corners. By forming the second cathode terminal portion 46 to the end of the mounting substrate 41, a solder fillet is formed between the conductive pattern of the wiring board to be mounted and the second cathode terminal portion 46, Visibility of surely soldering connection is improved.

  Further, as shown in FIG. 9, the first cathode terminal portion formed on the mounting substrate 41 is not a pattern in which the entire surface is exposed, but a conductive pattern at the center of the first cathode terminal portion 43 formed in a square shape. The central portion may be an insulating region without forming a so-called "shaped". If the first cathode terminal portion 43 is formed in a mouth shape in this way, the current path of the first cathode terminal portion 43 is narrowed and the current is concentrated. In addition, since the first cathode terminal portion where the current is concentrated is arranged so as to be close to the anode terminal portion 42, the effect of canceling the induced magnetic field can be further enhanced, and the overall ESL reduction effect can be achieved. A further improved solid electrolytic capacitor can be realized. In order to make such a first cathode terminal portion 43, a conductive pattern is not formed in advance, and the first cathode terminal portion 43 is formed with a conductive pattern on the entire surface, and the central portion is covered with a resist layer. Thus, the central portion can be an insulating region.

  Even when the first cathode terminal portion 43 is formed in such a so-called square shape, the outer peripheral region of the first cathode terminal portion 43 is formed in a region substantially equal to the size of the cathode lead portion of the capacitor element. Thus, the anode and the cathode are arranged closest to each other, and the effect of canceling the induced magnetic field is large and preferable.

  In terms of the characteristics of the solid electrolytic capacitor as a single unit, it is preferable that the shape of the first cathode terminal is a square shape as described above, but the pattern arrangement of the substrate on which the solid electrolytic capacitor is mounted In addition, the shape of the first cathode terminal portion can be arbitrarily changed depending on the terminal arrangement of the IC supplied with power by the solid electrolytic capacitor or the amount of electric power required. For example, in FIG. 7, the shape of the first cathode terminal portion 43 is not a perfect square, but an octagonal shape in which square corners are cut.

  Next, a process for mounting the capacitor element on the mounting substrate will be described. Here, an example in which the capacitor element 20 of the second embodiment described above is used as the capacitor element will be described.

  As shown in FIG. 8, the capacitor element 20 is mounted on a mounting substrate 41, and the cathode lead portion 22 of the capacitor element 20 and the cathode conductor 45 of the mounting substrate are joined together by a conductive adhesive. Further, the anode lead portion 21 of the capacitor element 20 and the anode conductor 44 are connected. At this time, the anode lead portion 21 of the capacitor element 20 is aluminum, and the wettability with the silver paste or the like is not good, and adhesion with the silver paste may be difficult. In such a case, a connecting member 27 such as a copper material is connected to the anode lead portion 21 of the capacitor element 20 by laser welding, ultrasonic welding or the like, and this connecting member 27 is electrically conductive such as silver paste. It is preferable to join the anode conductor 44 of the mounting substrate 41 with an adhesive.

  Further, the number of capacitor elements mounted on the mounting substrate 41 is not limited to one. When a large capacitance is required, capacitor elements can be further stacked to achieve the required capacitance.

  Then, for the purpose of mechanical protection of the capacitor element mounted on the mounting substrate and shielding from the outside air, the exterior is formed by molding with an exterior resin. In addition, you may package an exterior by sticking to a board | substrate using a resin case.

DESCRIPTION OF SYMBOLS 10 Capacitor element 11 Capacitor element piece 12 Anode extraction part 13 Cathode extraction part 14 Separation part 15 Etching layer 20 Capacitor element 21 Capacitor element piece 22 Anode extraction part 23 Cathode extraction part 24 Separation part 25 Etching layer 27 Connection member 30 Capacitor element 32 Anode lead part 33 Cathode lead part 34 Separation part 35 Etching layer 41 Mounting substrate 42 Anode terminal part 43 First cathode terminal part 44 Anode conductor 45 Cathode conductor 46 Second cathode terminal part 47 Auxiliary conductor 48 Through hole (conductor)

Claims (3)

In a solid electrolytic capacitor comprising a capacitor element in which a dielectric layer, a solid electrolyte layer, and a cathode lead portion are sequentially formed on an anode body having an anode lead portion,
The first cathode terminal portion is arranged at the center of the mounting surface facing the wiring board,
While arranging the anode terminal part around the first cathode terminal part,
A solid electrolytic capacitor in which a second cathode terminal portion is arranged at a position adjacent to the anode terminal portion ,
The first cathode terminal portion disposed in the center of the mounting surface is formed in an area substantially equal to the size of the cathode lead portion of the capacitor element, and is larger than the anode terminal portion and the second cathode terminal portion. Solid electrolytic capacitor as an area. A capacitor element in which a dielectric layer, a solid electrolyte layer, and a cathode lead portion are sequentially formed on an anode body having an anode lead portion;
The capacitor element mounting surface and a mounting surface facing the wiring board are provided, and on the surface on which the capacitor element is mounted, conductors respectively corresponding to the anode lead part and the cathode lead part of the capacitor element are formed. The mounting surface facing the surface is formed with an anode terminal and a cathode terminal, and the conductor comprises a mounting substrate that penetrates the inside and is electrically connected to the anode terminal and the cathode terminal, respectively.
On the mounting surface of the mounting substrate, a first cathode terminal portion is arranged in the center of the mounting substrate,
While arranging the anode terminal part on the four sides of the mounting substrate so as to surround the outer periphery of the first cathode terminal part,
A solid electrolytic capacitor in which second cathode terminal portions are arranged at positions adjacent to the anode terminal portions at the four corners of the mounting substrate ;
The first cathode terminal portion disposed in the center of the mounting surface is formed in an area substantially equal to the size of the cathode lead portion of the capacitor element, and is larger than the anode terminal portion and the second cathode terminal portion. Solid electrolytic capacitor as an area. 3. The solid electrolytic capacitor according to claim 1 , wherein the first cathode terminal portion is disposed in a central portion of the mounting surface and in a region close to each anode terminal portion, and the central portion is an insulating region. .