JP2019075582A - Solid-state electrolytic capacitor - Google Patents

Abstract

To provide a three-terminal type solid-state electrolytic capacitor which is excellent in noise cancellation effect over wide frequency bands and enables heavy current to flow.SOLUTION: A pair of cathode terminals 26 and 27 is disposed on a pair of end faces 22 and 23 in a main body 25 of a solid-state electrolytic capacitor 21, and an anode terminal 28 is disposed on a bottom face 24. A capacitor element 30 provided in the main body 25 comprises: a linear through-conductor 31 consisting of valve action metal; a dielectric layer located on the through-conductor 31; and an anode-side functional layer 36 which is located on the dielectric layer and electrically connected with the anode terminal 28. The through-conductor 31 consists of a core part 32 and a porous part 33 covering a peripheral surface of the core part. Both end faces of the core part 32 of the through-conductor 31 are exposed from a shield member 29 in a state that the faces extend in a direction perpendicular to an axis direction of the through-conductor 31, and are covered and brought into contact with the pair of cathode terminals 26 and 27, respectively on each of the pair of end faces 22 and 23 of the main body 25.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a solid electrolytic capacitor, and more particularly to a three-terminal type solid electrolytic capacitor in which power is supplied through a through conductor made of a valve metal.

  The solid electrolytic capacitor is not only used as a general capacitor in a decoupling circuit or a power supply circuit, but is also advantageously used as a noise filter for removing high frequency noise.

  Prior art of interest to this invention is, for example, that described in WO 2005/015588. In particular, the solid electrolytic capacitors described in FIGS. 10 and 11 of Patent Document 1 are noted. The solid electrolytic capacitor will be described with reference to FIG. 8 attached hereto.

  As shown in FIG. 8, the solid electrolytic capacitor 1 is provided so as to penetrate the porous sintered body 2 having a valve action and formed of metal particles or conductive ceramic particles, and the porous sintered body 2, and both ends thereof And an anode wire 3 protruding from the porous sintered body 2. Each end of the anode wire 3 protruding from the porous sintered body 2 is electrically connected to anode terminals 4 and 5 formed of a metal plate bent in a substantially C-shaped cross section.

  On the other hand, conductive resins 6 and 7 to be cathodes are respectively disposed on the upper and lower surfaces of the porous sintered body 2, and further, cathode plates 8 and 9 made of metal plates via the conductive resins 6 and 7. Is glued. Although not shown, the upper cathode plate 8 and the lower cathode plate 9 are electrically connected to each other by a conductive member disposed along the side surface of the porous sintered body 2. A cathode terminal 10 is connected to a cathode plate 9 disposed below the porous sintered body 2. The cathode terminal 10 is formed of a metal plate bent in a U-shaped cross section.

  Further, the porous sintered body 2 is covered with the sealing resin 11. Here, a part of each of the anode terminals 4 and 5 and the cathode terminal 10 described above is exposed from the sealing resin 11 in order to enable electrical connection with an external mounting substrate.

  Such a solid electrolytic capacitor 1 is used to supply power from one anode terminal 4 or 5 to the other anode terminal 5 or 4 while removing noise. At this time, according to the solid electrolytic capacitor 1, most of the current input thereto passes through the anode wire 3, so that the electrical loss in the solid electrolytic capacitor 1 can be reduced. Moreover, since the current flowing in the porous sintered body 2 is small, the heat generation in the porous sintered body 2 can be suppressed.

WO 2005/015588

  However, the above-described solid electrolytic capacitor 1 has the following problems to be solved.

  FIG. 9 is an equivalent circuit diagram given by the solid electrolytic capacitor 1.

  Referring to FIG. 8 together with FIG. 9, capacitance C1 is a capacitance formed between anode wire 3 and cathode plates 8 and 9, and resistance R3 and inductance L4 are cathodes from cathode plates 8 and 9, respectively. These are the resistance and parasitic inductance that exist in the conductive path leading to the mounting portion of the terminal 10. The inductance L 1 is a parasitic inductance mainly generated by the anode wire 3. Resistance R1 and inductance L2 are respectively a resistance and a parasitic inductance which exist in the conductive path from one end of anode wire 3 to the mounting portion of anode terminal 4. Resistance R2 and inductance L3 are respectively a resistance and a parasitic inductance which exist in the conductive path from the other end of anode wire 3 to the mounting portion of anode terminal 5.

  In the solid electrolytic capacitor 1 represented by such an equivalent circuit diagram, the parasitic inductances L2 and L3 first become large. This is because the conductive path extending from one end of the anode wire 3 to the mounting portion of the anode terminal 4 and the conductive path extending from the other end of the anode wire 3 to the mounting portion of the anode terminal 5 are relatively long. And 5 do not extend linearly, but have some folds.

  As described above, when the parasitic inductances L2 and L3 increase, the noise removal performance in the high frequency band of the solid electrolytic capacitor 1 decreases.

  Also, the resistances R1 and R2 become relatively large. Because, as described above, in addition to the conductive path from one end of anode wire 3 to the mounting portion of anode terminal 4 and the conductive path from the other end of anode wire 3 to the mounting portion of anode terminal 5 being relatively long. A connecting portion between one end of the anode wire 3 and the anode terminal 4 and a connecting portion between the other end of the anode wire 3 and the anode terminal 5 are formed on the peripheral surface portion of the cylindrical anode wire 3 and each of the anode terminals 4 and 5 It is because it is based on the line contact by a plane part.

  As described above, when the resistances R1 and R2 are large, the current that can be supplied to the solid electrolytic capacitor 1 is reduced.

  Further, in the solid electrolytic capacitor 1, the proportion of the members such as the anode terminals 4 and 5 which do not contribute to the formation of the capacitance in the total volume is relatively high and the volumetric efficiency is low. Therefore, it is difficult to miniaturize and increase the capacity.

  Therefore, an object of the present invention is to provide a solid electrolytic capacitor that can solve the problems described above.

  In order to solve the technical problems described above, a solid electrolytic capacitor according to the present invention comprises a main body having a pair of end surfaces facing each other and a bottom surface adjacent to the end surfaces, and a pair of the end surfaces of the main body An anode terminal and a cathode terminal on the bottom of the body.

  The main body includes a sealing material containing a resin and a capacitor element covered with the sealing material.

  The capacitor element includes a linear through conductor made of a valve metal, a dielectric layer on the through conductor, and a cathode side functional layer on the dielectric layer and electrically connected to the cathode terminal. Prepare.

  The penetrating conductor includes a core extending in the axial direction of the penetrating conductor, and a porous portion covering the circumferential surface of the core and having a large number of pores. The dielectric layer described above is formed along the inner circumferential surface of the pores of the porous portion.

  Then, both end surfaces of the core portion of the through conductor are exposed from the sealing material so as to extend in a direction perpendicular to the axial direction of the through conductor, and one pair is formed on each of the pair of end surfaces of the main body. It is characterized in that it is covered and in contact with the respective anode terminals of.

  Thus, a pair of anode terminals is disposed on a pair of end faces of the main body, and both end faces of the core of the through conductor are covered with a pair of anode terminals respectively on each of the pair of end faces of the main body Since the pair of anode terminals are in contact with each other, the conductive path length on the anode terminal side can be shortened.

  In the present invention, the cathode-side functional layer preferably includes, as a solid electrolyte, a conductive polymer layer filling at least a part of the pores of the porous portion. According to this configuration, the conductive polymer layer as the cathode side functional layer and the dielectric layer can be in contact in a wide area.

  Furthermore, in the present invention, it is preferable to further include an electrical insulating member disposed between the cathode side functional layer and the anode terminal. Thus, the electrical insulation between the cathode-side functional layer and the anode terminal can be ensured with high reliability.

  It is more preferable that the above-mentioned electrical insulation member is in contact with the core. According to this configuration, in order to form the anode terminal, for example, when wet plating is applied, it is possible to make it difficult for the plating solution to penetrate and remain in the porous portion. In the configuration described above, in the portion where the electrical insulating member is in contact with the core portion, there are cases where the electrical insulating member fills the pores in the porous portion and cases where the porous portion does not exist. .

  The through conductor has a form in which the peripheral surface of the core portion is covered with the porous portion, and in particular, a columnar shape is preferable. The term “cylindrical shape” includes a shape in which the ridge line portion of an elliptic cylindrical shape, a flat columnar shape, or a prism is chamfered. When the through conductor is cylindrical, no corner is present on the circumferential surface. Therefore, the formability of the cathode side functional layer such as the conductive polymer layer can be made excellent. Therefore, between the element on the anode side and the element on the cathode side disposed via the cathode side functional layer Unwanted contact can be made less likely to occur.

  If there is a corner on the peripheral surface, for example, part of the corner can not be covered and the through conductor is exposed to make it easy to cause a defect of the capacitor, and even if it is covered, the formed thickness becomes thinner at the corner The flat portion tends to be thick and lack uniformity, so the capacitor element becomes thick, and as a result, it becomes difficult to reduce the height of the capacitor. That is, having excellent formability of the cathode side functional layer means that the thickness of each element constituting the cathode side functional layer is excellent in uniformity. Therefore, it is preferable that the through conductor has no corner on its circumferential surface. Here, the term "corner" means a non-rounded portion such as an acute angle or an obtuse angle.

  Further, when molding the sealing material containing a resin, the external stress applied to the through conductor is advantageously dispersed since the through conductor has a cylindrical shape. Therefore, damage to the through conductor can be advantageously avoided during molding of the sealing material.

  Moreover, it is excellent in the filling property of a sealing material that a penetration conductor is cylindrical shape. Therefore, since the package effect by the sealing material is high, it is possible to obtain a solid electrolytic capacitor having high moisture and air blocking properties and excellent in moisture resistance and heat resistance.

  Moreover, since the whole circumferential surface can be used as a capacity appearance part if the through conductor has a cylindrical shape, the area of the capacity appearance part is about 1 as compared with, for example, a metal foil such as aluminum foil. .5 times can be spread.

  The anode terminal preferably includes a plating film or a conductive resin film, or both of them.

  The porous portion preferably comprises an etching treated portion formed on the circumferential surface of the linear through conductor. That is, the through conductor is obtained by etching the surface of the metal wire such that the core remains. According to this configuration, the cross-sectional area ratio of the core portion as the anode can be arbitrarily and easily adjusted while securing conduction between the core portion and the porous portion. By adjusting the ratio of the core part to the total of the core part and the porous part in the cross-sectional area (that is, the cross-sectional area ratio), it is possible to adjust the size of the capacity and the degree of contact with the anode terminal. For example, if this ratio is large, the contact surface of the core with the anode terminal will be large. That is, the resistance at the electrical connection portion is low, which is advantageous, for example, for flowing a large current. In addition, the adhesion area between the core and the plating film can be secured more, which advantageously affects, for example, long-term durability. Although these are only examples of description, it is preferable to adjust and use the cross-sectional area ratio of a core part according to various requirements.

  On the other hand, in the case of a porous sintered body as described in Patent Document 1, necking technology between particles / particles and particles / wires is indispensable in order to ensure conduction between the sintered portion and the wire. , The manufacturing process becomes complicated.

  In the solid electrolytic capacitor according to the present invention, if lower ESR (equivalent series resistance) and larger capacity are desired, the main body preferably includes a plurality of capacitor elements. In this case, the plurality of capacitor elements are connected in parallel via the anode terminal and the cathode terminal.

  The cathode terminal is preferably made of a metal plate. The metal plate is superior to the printed circuit board and the resin plate in heat dissipation. Further, compared to the printed circuit board, it is not necessary to form through-hole conductors or via conductors for wiring the capacitor element and the mounting side terminal, and the metal plate provides a conductive path on all the surfaces thereof. The path length can be shortened. In addition, the metal plate is thin and excellent in strength, which is advantageous for reducing the height of the solid electrolytic capacitor. Moreover, compared with the printed circuit board, the metal plate is inexpensive, which is advantageous for cost reduction of the solid electrolytic capacitor.

  According to the present invention, a pair of anode terminals is disposed on a pair of end surfaces of the main body, and both end surfaces of the core in the through conductor are covered with the pair of anode terminals and are respectively brought into contact with the pair of anode terminals. Therefore, the conductive path length on the anode terminal side can be shortened. Therefore, the parasitic inductance generated in the conductive path on the anode terminal side can be reduced, and the noise removal performance in the high frequency band of the solid electrolytic capacitor can be enhanced.

  Further, as described above, according to the present invention, both ends of the core portion of the through conductor are covered with a pair of anode terminals and are respectively in contact with a pair of anode terminals. It can be surface contact between wide surfaces. Therefore, the resistance at the electrical connection portion between the core of the through conductor and the anode terminal can be suppressed low. Therefore, a large current can be supplied to the solid electrolytic capacitor.

  Further, according to the present invention, the anode terminal which does not contribute to the capacitance formation is disposed on the end surface of the main body, and the end surface of the core of the through conductor directly contacts this anode terminal. The ratio of the non-members to the total volume is relatively low, and the volumetric efficiency is high. Therefore, it is suitable for small size and large capacity. Moreover, the noise removal performance in the frequency band resulting from capacity | capacitance can be improved. Therefore, according to the present invention, the noise removal performance can be enhanced in a wide frequency band including the high frequency band due to the parasitic inductance and the frequency band due to the capacitance.

  Further, according to the present invention, in the solid electrolytic capacitor 1 described in Patent Document 1 and shown in FIG. 8, the functions of the two parts of the porous sintered body 2 and the anode wire 3 are the core portion and the porous portion. As a result, it is possible to reduce the number of parts and to reduce the cost accordingly.

It is a perspective view which shows the external appearance of the solid electrolytic capacitor 21 by 1st Embodiment of this invention. It is sectional drawing in alignment with line | wire II-II of FIG. It is a bottom view of the solid electrolytic capacitor 21 shown in FIG. It is sectional drawing in alignment with line | wire IV-IV of FIG. It is sectional drawing which expands the part V of FIG. 2, and is shown typically. It is for demonstrating the 2nd Embodiment of this invention, and is sectional drawing which expands the part VI of FIG. 2, and is shown typically. It is a front view center cross-sectional view showing a solid electrolytic capacitor 21a according to a third embodiment of the present invention. It is a top view center cross-sectional view which shows the solid electrolytic capacitor 1 described in patent document 1. FIG. It is an equivalent circuit schematic of the solid electrolytic capacitor 1 shown in FIG.

  A solid electrolytic capacitor 21 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

  The solid electrolytic capacitor 21 is disposed at a pair of end faces 22 and 23 of a rectangular parallelepiped main body 25 having a pair of end faces 22 and 23 facing each other and a bottom 24 adjacent to the end faces 22 and 23. A pair of anode terminals 26 and 27 and a cathode terminal 28 on the bottom surface 24 of the body 25 are provided.

  The main body 25 includes a sealing material 29 containing a resin, and the capacitor element 30 covered with the sealing material 29.

  The capacitor element 30 includes a linear through conductor 31 made of a valve metal. As a valve metal which comprises the penetration conductor 31, for example, aluminum, tantalum, niobium, titanium, or an alloy containing at least one of these is used. The through conductor 31 is cylindrical in this embodiment. Preferably, an aluminum wire is used as the through conductor 31 in terms of low cost and easy availability.

  The through conductor 31 includes a core portion 32 extending in the axial direction of the through conductor 31 and a porous portion 33 which covers the circumferential surface of the core portion 32 and has a large number of pores. The porous portion 33 is formed, for example, by subjecting the peripheral surface of the through conductor 31 made of aluminum wire to an etching process to roughen the peripheral surface. In the porous portion 33, as schematically shown in FIG. 5, a large number of pores 34 having openings directed outward are formed. In FIG. 2 and FIG. 4, the porous portion 33 is shown as a shaded area sandwiched by thick dotted lines.

  Further, as shown in FIG. 5, the capacitor element 30 includes a dielectric layer 35 on the through conductor 31. The dielectric layer 35 is formed, for example, by oxidizing the surface of the through conductor 31 in which the porous portion 33 is formed. In FIG. 5, the dielectric layer 35 is shown by a thick line. The dielectric layer 35 is formed along the inner circumferential surface of the pore 34 of the porous portion 33.

  The capacitor element 30 further includes a cathode side functional layer 36 located on the dielectric layer 35. The cathode side functional layer 36 includes a conductive polymer layer 37 as a solid electrolyte, a carbon layer 38 thereon, and a silver layer 39 thereon. The conductive polymer layer 37 is provided to fill at least a part of the pores 34 of the porous portion 33, as shown in FIG. Thereby, the conductive polymer layer 37 and the dielectric layer 35 can be in contact with each other over a wide area. The carbon layer 38 and the silver layer 39 in the cathode-side functional layer 36 function as a cathode layer of the capacitor element 30. That is, the cathode side functional layer 36 includes the conductive polymer layer 37 and the cathode layer on the conductive polymer layer 37. The cathode layer may be a layer having conductivity. In the present embodiment, the cathode layer is a plurality of layers of the carbon layer 38 and the silver layer 39, but the cathode layer may be constituted of only the silver layer 39.

  The cathode side functional layer 36, more specifically, the silver layer 39 is electrically connected to the cathode terminal 28, for example, via the conductive adhesive 40 (see FIG. 4). The cathode terminal 28 is formed of a metal plate.

  Both end surfaces of the core portion 32 of the through conductor 31 are exposed from the sealing material 29 so as to extend in a direction perpendicular to the axial direction of the through conductor 31, and the end surfaces 22 and 23 of the pair of end surfaces of the main body 25. Each is covered and in contact with a pair of anode terminals 26 and 27, respectively. Anode terminals 26 and 27 are formed on the end face of core portion 32 of through conductor 31 as shown in FIG. 2, for example, a metal such as nickel, zinc, copper, tin, gold, silver, palladium or lead, or It consists of a plating film containing an alloy containing at least one of these metals, or a conductive resin film containing, for example, at least one of silver, copper, nickel, tin and palladium as a conductive component. Alternatively, anode terminals 26 and 27 may have a multilayer structure including a plating film and a conductive resin film. For example, the anode terminals 26 and 27 may include two plating layers and a conductive resin layer between the plating layers.

  It is to be noted that, for example, connecting metal pieces or metal lead materials to anode terminals 26 and 27 by laser welding, resistance welding, ultrasonic welding or the like is caused by mechanical damage, contact dispersion or the like. This is not a preferable mode because it is a factor of occurrence of defects.

  An electrically insulating member 43 made of electrically insulating resin is disposed between the cathode side functional layer 36 and the anode terminals 26 and 27. Thereby, the electrical insulation between the cathode side functional layer 36 and the anode terminals 26 and 27 can be reliably realized. In this embodiment, the electrical insulation member 43 is provided so that the porous portion 33 is removed at both end portions of the through conductor 31 and the core portion 32 is exposed and then the core portion 32 is in contact. That is, in the electrical insulating member 43, the porous portion 33 does not exist.

  In the second embodiment of the present invention, as shown in FIG. 6, in the portion where the electrical insulating member 43 is in contact with the core portion 32, the electrical insulating member 43 fills the pores 34 in the porous portion 33. May be provided. That is, in the electrically insulating member 43, the porous portion 33 is present.

  The electrically insulating member 43 is in contact with the core 32 in any of the two cases described above. According to this configuration, since the anode terminals 26 and 27 are formed, for example, when wet plating is applied, it is possible to make it difficult for the plating solution to infiltrate and remain in the porous portion 33.

  The sealing material 29 contains a resin. In addition to the resin, the sealing material 29 may contain a filler such as alumina or silica, or a magnetic material. The mechanical strength and processability of the sealing material 29 can be adjusted by including the filler in the sealing material 29. Also, heat shrinkage can be adjusted by selecting a filler having a desired linear expansion coefficient. When the sealing material 29 contains a magnetic material, the impedance of the capacitor can be intentionally increased. For example, anti-resonance may occur when a plurality of low impedance capacitors are mounted in parallel. At this time, when the sealing material contains a magnetic material, anti-resonance can be suppressed. As the magnetic material, for example, magnetic powder such as iron powder, powder of an alloy containing iron, or powder of ferrite is used. The magnetic material may be a mixture of two or more powders of different particle size or of different composition. Thus, it is preferable to select and use a desired filler or magnetic material according to the required function.

  According to the solid electrolytic capacitor 21 described above, the pair of anode terminals 26 and 27 are disposed on the pair of end surfaces 22 and 23 of the main body 25, and both end surfaces of the core portion 32 in the through conductor 31 Since the terminals 26 and 27 cover and contact the pair of anode terminals 26 and 27, respectively, the conductive path length on the anode terminals 26 and 27 can be shortened. Therefore, in the equivalent circuit of FIG. 9, the parasitic inductances corresponding to parasitic inductances L2 and L3 generated in the conductive paths on the side of anode terminals 4 and 5 can be reduced, and solid electrolytic capacitor 21 in the high frequency band (ωL). Noise removal performance can be enhanced.

  The anode terminals 26 and 27 which do not contribute to the formation of capacitance are disposed on the end faces 22 and 23 of the main body 25, and the end faces of the core portion 32 of the through conductor 31 are in direct contact with the anode terminals 26 and 27. Because of this, the proportion of members that do not contribute to capacity formation in the total volume is relatively low, and the volume efficiency is high. Therefore, it is suitable for small size and large capacity. Therefore, high noise removal performance can be exhibited even in the frequency band (1 / ωC) caused by the capacitance.

  Therefore, according to the solid electrolytic capacitor 21 described above, high noise removal performance can be exhibited in a wide frequency band including the high frequency band caused by the inductance and the frequency band caused by the capacitance.

  Further, since both end surfaces of core portion 32 of through conductor 31 are in surface contact with a pair of anode terminals 26 and 27 with relatively large surfaces, core portion 32 of through conductor 31 and anode terminals 26 and 27 are provided. The resistance at the electrical connection portion with this, that is, the resistance corresponding to the resistors R1 and R2 shown in FIG. 9 can be suppressed low. Therefore, a large current can be supplied to the solid electrolytic capacitor 21.

  Further, unlike the case of the cathode terminal 10 shown in FIG. 8, since the cathode terminal 28 is not due to bending of the metal plate, the parasitic inductance L4 shown in FIG. 9 generated in the conductive path on the cathode terminal 28 side is The corresponding parasitic inductance can be reduced.

  The solid electrolytic capacitor 21 described above is manufactured, for example, as follows.

A porous portion 33 is formed as the through conductor 31 by being subjected to an etching process, and further, a cylindrical shape having a diameter of 0.8 mm and a length of 2.0 mm provided with a dielectric layer 35 formed by anodization. Prepare the aluminum wire of Here, as an example, in order to measure the withstand voltage of the dielectric layer 35 formed in the through conductor 31, a constant current of 0.35 mA / cm ^{2 is applied} for 180 seconds in an aqueous solution of ammonium adipate at normal temperature. , 60V withstand voltage was observed. In the through conductor 31, the thickness of the porous portion 33 is, for example, 0.05 mm.

  The cross-sectional diameter of the through conductor 31 is 0.8 mm, the diameter of the core portion 32 is 0.7 mm, and the remaining portion is the porous portion 33. Accordingly, the diameter ratio occupied by the core portion 32 to the porous portion 33 is 0.7 / 0.1 = 7.0.

  Next, an electrically insulating resin is applied around both ends of the through conductor 31 made of aluminum wire and dried to form an electrically insulating member 43 having a thickness of 0.05 mm, for example. The electrically insulating member 43 is in a state in which the pores 34 in the porous portion 33 are filled. The porous portion 33 may be removed before applying the electrically insulating resin.

  Next, after a conductive polymer layer 37 as a solid electrolyte is formed on the peripheral surface of the through conductor 31 other than the portion where the electrical insulating member 43 is disposed, a carbon layer 38 as a cathode and a silver layer 39 are formed. Form The conductive polymer layer 37 is formed by chemical oxidation polymerization in which a reaction solution consisting of a monomer precursor of a polymer, a dopant and an oxidizing agent is alternately applied and polymerized, or electrochemically in the reaction solution. It can be formed by electrolytic polymerization in which a polymerization reaction is performed, or a method in which a solution in which a conductive polymer in which conductivity has been developed in advance is dissolved or dispersed in an arbitrary solvent is applied.

  As an example, in order to form the cathode side functional layer 36, a conductive polymer solution in which poly (3,4-ethylenedioxythiophene) is dispersed as a solid electrolyte is applied while being permeated into the porous portion 33 and dried to be conductive. A polymer layer 37 was formed, and then a carbon paste was applied and dried, and then a silver paste was applied and dried to form a carbon layer 38 and a silver layer 39 sequentially. Here, the thickness of the conductive polymer layer 37 on the porous portion 33 was, for example, 0.01 mm, and each thickness of the carbon layer 38 and the silver layer 39 was also, for example, 0.01 mm.

  As a result of measuring a capacity of 120 Hz using the LCR meter, the capacitor element 30 obtained in this manner was 1.0 μF. Next, a voltage of 25 V was applied to the element 30 for 1 minute to measure a leakage current, which was 2.1 nA. The leakage current was extremely small and good (CV equivalent: approximately 0.0001 CV).

  In the process described above, since the through conductor 31 has a cylindrical shape, the formability of the conductive polymer layer 37, the carbon layer 38 and the silver layer 39 is good. In addition, when the through conductor 31 has a cylindrical shape, the entire circumferential surface can be used as a capacity appearance portion.

  Next, the cathode side functional layer 36 on the through conductor 31 is adhered with a conductive adhesive 40 to a metal plate to be a cathode terminal 28 having a thickness of 0.1 mm and a width of 1.2 mm, for example, The resin is molded so that the sealing material 29 is formed such that the surface facing the same and both end surfaces of the through conductor 31 are exposed. The exposure of both end surfaces of the through conductor 31 is preferably performed by dicing rather than by polishing. This is because a more uniform exposed surface can be obtained, and good contact can be obtained in forming the anode terminals 26 and 27.

  Since the through conductor 31 has a cylindrical shape at the time of molding the sealing member 29, external stress applied to the through conductor 31 is advantageously dispersed, and a situation where the through conductor 31 is damaged can be advantageously avoided. The damage leads to problems such as increased leakage current. Moreover, since the through conductor 31 has a cylindrical shape, the filling property of the sealing material 29 is excellent. For example, a gap is not easily generated between the capacitor element 30 and the sealing material 29, and the height by the sealing material 29 is high. The package effect can be obtained.

  Next, anode terminals 26 and 27 are formed to be connected to both end surfaces of through conductor 31 exposed from sealing material 29. For the formation of anode terminals 26 and 27, for example, a plating film is formed, and then a conductive resin film is formed with a thickness of, for example, 0.01 mm. Alternatively, only the plating film may be formed or only the conductive resin film may be formed to form the anode terminals 26 and 27.

  As described above, a solid electrolytic capacitor 21 having an outer dimension of, for example, 2.02 mm (longitudinal dimension) × 1.22 mm (widthwise dimension) × 1.22 mm (heightwise dimension) is completed. As an example, as a result of measuring the capacity | capacitance of 120 Hz using the LCR meter, as a solid electrolytic capacitor 21 obtained in this way, it was 1.0 μF. Next, a voltage of 25 V was applied to the capacitor for 1 minute to measure a leakage current, which was 2.0 nA. The increase in the leakage current was not observed and was good.

  Next, a solid electrolytic capacitor 21a according to a third embodiment of the present invention will be described with reference to FIG. Although FIG. 7 is a front cross-sectional center cross-sectional view, in FIG. 7, the same referential mark is attached to the element equivalent to the element shown in FIG.

  The solid electrolytic capacitor 21 a shown in FIG. 7 is characterized in that the main body 25 includes a plurality of, for example, two capacitor elements 30. The two capacitor elements 30 are covered by the sealing material 29 in a side-by-side manner.

  The anode terminals 26 and 27 are formed on the end faces 22 and 23 of the main body 25 so as to electrically connect the cores 32 of the through conductors 31 in each of the two capacitor elements 30 to each other.

  On the other hand, although the cathode terminal 28 is shown by a dotted line in FIG. 7, the main body 25 is such that the silver layers 39 included in the cathode side functional layer 36 in each of the two capacitor elements 30 are electrically connected to each other. Provided along the bottom of the

  Thus, the two capacitor elements 30 are connected in parallel via the anode terminals 26 and 27 and the cathode terminal 28. Thereby, according to the solid electrolytic capacitor 21a, lower ESR and larger capacity can be realized as compared with the solid electrolytic capacitor 21 described above.

  Although the present invention has been described above in connection with the illustrated embodiments, these embodiments are illustrative, and it is possible that partial replacement or combination of configurations is possible between different embodiments. Point out.

21 and 21a solid electrolytic capacitors 22 and 23 end face 24 bottom surface 25 main body 26, 27 anode terminal 28 cathode terminal 29 sealing material 30 capacitor element 31 through conductor 32 core portion 33 porous portion 34 pore 35 dielectric layer 36 cathode side functional layer 37 Conductive Polymer Layer 38 Carbon Layer 39 Silver Layer 43 Electrical Insulating Member

Claims (12)

A body having a pair of opposed end faces and a bottom adjacent to the end faces;
A pair of anode terminals disposed on the pair of end faces of the body;
A cathode terminal at the bottom of the body;
Equipped with
The body is
A sealing material containing a resin,
A capacitor element covered by the sealing material;
Equipped with
The capacitor element is
A linear through conductor made of valve metal,
A dielectric layer on the through conductor;
A cathode side functional layer on the dielectric layer and electrically connected to the cathode terminal;
Equipped with
The through conductor includes a core extending in the axial direction of the through conductor, and a porous portion covering a circumferential surface of the core and having a large number of pores.
The dielectric layer is formed along the inner circumferential surface of the pores of the porous portion,
Both end surfaces of the core portion of the through conductor are exposed from the sealing material so as to extend in a direction perpendicular to the axial direction of the through conductor, and each end surface of the pair of main bodies is exposed. Respectively covered and in contact with the pair of anode terminals,
Solid electrolytic capacitor.   The solid electrolytic capacitor according to claim 1, wherein the cathode side functional layer comprises a conductive polymer layer filling at least a part of the pores of the porous portion.   The solid electrolytic capacitor according to claim 1, further comprising an electrical insulating member disposed between the cathode side functional layer and the anode terminal.   The solid electrolytic capacitor according to claim 3, wherein the electrically insulating member is in contact with the core portion.   The solid electrolytic capacitor according to claim 4, wherein in the portion where the electrical insulating member is in contact with the core portion, the electrical insulating member fills the pores in the porous portion.   The solid electrolytic capacitor according to claim 4, wherein the porous portion does not exist in a portion where the electrical insulating member is in contact with the core portion.   The solid electrolytic capacitor according to any one of claims 1 to 6, wherein the through conductor is cylindrical.   The solid electrolytic capacitor according to any one of claims 1 to 7, wherein the anode terminal includes a plating film.   The solid electrolytic capacitor according to any one of claims 1 to 8, wherein the anode terminal includes a conductive resin film.   The solid electrolytic capacitor according to any one of claims 1 to 9, wherein the porous portion comprises an etching treated portion formed on a circumferential surface of the linear through conductor.   The solid electrolysis according to any one of claims 1 to 10, wherein the main body includes a plurality of the capacitor elements, and the plurality of capacitor elements are connected in parallel via the anode terminal and the cathode terminal. Capacitor.   The solid electrolytic capacitor according to any one of claims 1 to 11, wherein the cathode terminal is made of a metal plate.

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