JP6925577B2 - Solid electrolytic capacitors - Google Patents

Description

The present invention relates to a solid electrolytic capacitor, and more particularly to a three-terminal type solid electrolytic capacitor that supplies power through a through conductor made of a valve acting 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.

As a prior art of interest for the present invention, for example, there is one described in International Publication No. 2005/015588 (Patent Document 1). In particular, the solid electrolytic capacitors described in FIGS. 10 and 11 of Patent Document 1 are of particular interest. This solid electrolytic capacitor will be described with reference to FIG. 8 attached.

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

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

Further, the porous sintered body 2 is covered with the sealing resin 11. Here, each part 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 here passes through the anode wire 3, so that the electrical loss in the solid electrolytic capacitor 1 can be reduced. Further, since the current flowing in the porous sintered body 2 is small, heat generation in the porous sintered body 2 can be suppressed.

International Publication No. 2005/015588

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

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

With reference to FIG. 9, the capacitance C1 is the capacitance formed between the anode wire 3 and the cathode plates 8 and 9, and the resistors R3 and the inductance L4 are the cathodes from the cathode plates 8 and 9, respectively. It is a resistance and a parasitic inductance existing in the conductive path leading to the mounting portion of the terminal 10. The inductance L1 is a parasitic inductance mainly generated by the anode wire 3. The resistor R1 and the inductance L2 are the resistor and the parasitic inductance existing in the conductive path from one end of the anode wire 3 to the mounting portion of the anode terminal 4, respectively. The resistor R2 and the inductance L3 are the resistor and the parasitic inductance existing in the conductive path from the other end of the anode wire 3 to the mounting portion of the anode terminal 5, respectively.

In the solid electrolytic capacitor 1 represented by such an equivalent circuit diagram, first, the parasitic inductances L2 and L3 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 the anode terminal 4 This is because and 5 do not extend linearly, but have some bends.

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

Further, the resistors R1 and R2 become relatively large. This is because, as described above, the conductive path from one end of the anode wire 3 to the mounting portion of the anode terminal 4 and the conductive path from the other end of the anode wire 3 to the mounting portion of the anode terminal 5 are relatively long. , The connection portion between one end of the anode wire 3 and the anode terminal 4 and the connection portion between the other end of the anode wire 3 and the anode terminal 5 are the peripheral surface portion of the cylindrical anode wire 3 and the anode terminals 4 and 5, respectively. This is because it is based on line contact with the flat surface portion.

As described above, if the resistors R1 and R2 are large, the current that can be passed through the solid electrolytic capacitor 1 is reduced.

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

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

In order to solve the above-mentioned technical problems, the solid electrolytic capacitors according to the present invention are arranged on a pair of end faces facing each other and a rectangular parallelepiped main body having a bottom surface adjacent to the end faces and a pair of end faces of the main body. It includes a pair of anode terminals and a cathode terminal on the bottom surface of the main body.

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

The capacitor element is a columnar through conductor made of a valve acting metal , a dielectric layer on the peripheral surface of the through conductor, and a cathode side functional layer on the dielectric layer and electrically connected to the cathode terminal. And.

The through conductor includes a core portion extending in the axial direction of the through conductor, and a porous portion that covers the peripheral surface of the core portion and has a large number of pores. The dielectric layer described above is formed along the inner peripheral surface of the pores of the porous portion.

The peripheral surface of the penetrating conductor is sealed with a sealing material except for the portion connected to the cathode terminal, and both end faces of the core portion extend in a direction perpendicular to the axial direction of the penetrating conductor. The first feature is that it is exposed from the sealing material and is covered and in contact with the pair of anode terminals on each of the pair of end faces of the main body.

In this way, a pair of anode terminals are arranged on a pair of end faces of the main body, and both end faces of the core portion of the through conductor are covered with a pair of anode terminals on each of the pair of end faces of the main body. Since each pair of anode terminals is in contact with each other, the length of the conductive path 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 that fills 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 brought into contact with each other over a wide area.

Further, in the present invention, it is preferable to further include an electrically insulating member arranged between the cathode side functional layer and the anode terminal. As a result, the electrical insulation state between the cathode side functional layer and the anode terminal can be ensured with high reliability.

It is more preferable that the above-mentioned electrically insulating member is in contact with the core portion. According to this configuration, since the anode terminal is formed, for example, when wet plating is applied, it is possible to prevent the inconvenience that the plating solution permeates and remains in the porous portion. In the above-described configuration, in the portion where the electrically insulating member is in contact with the core portion, the electrically insulating member may be in a state of filling the pores in the porous portion, or the porous portion may not be present. ..

Through conductor, as described above, Ru circular columnar der that have a form in which the peripheral surface of the core portion is covered with a porous section. The columnar shape includes an elliptical columnar column, a flat columnar column, and a shape in which the ridgeline portion of the prism is chamfered. If the through conductor is columnar, there are no corners on its peripheral surface. Therefore, the formability of the cathode side functional layer such as the conductive polymer layer can be made excellent, and therefore, the anode side element and the cathode side element arranged via the cathode side functional layer can be made excellent. It is possible to prevent undesired contact from occurring.

If there are corners on the peripheral surface, for example, a part of the corners cannot be covered and the through conductor is exposed, which makes it easy to cause a capacitor failure. Even if the corners are covered, the formed thickness becomes thin at the corners. Since the flat portion becomes thick and tends to have poor uniformity, the capacitor element becomes thick, and as a result, it becomes difficult to reduce the height of the capacitor. That is, the 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 penetrating conductor has no corner on its peripheral surface. Here, the corner means a portion that is not rounded, such as an acute angle or an obtuse angle.

Further, when molding the sealing material containing the resin, the external stress applied to the penetrating conductor is advantageously dispersed because the penetrating conductor is cylindrical. Therefore, it is possible to advantageously avoid a situation in which the penetrating conductor is damaged during molding of the sealing material.

Further, when the through conductor is cylindrical, the filling property of the sealing material is excellent. Therefore, since the packaging effect of the sealing material is high, it is possible to obtain a solid electrolytic capacitor having high moisture and air blocking properties and excellent moisture resistance and heat resistance.

Further, if the penetrating conductor is cylindrical, the entire circumferential surface thereof can be used as the capacitance appearance portion, so that the area of the capacitance appearance portion is about 1 as compared with the case of a metal foil such as an aluminum foil, for example. It can be expanded 5 times.

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

The porous portion preferably comprises an etching-treated portion formed on the peripheral surface of the linear through conductor. That is, the through conductor is obtained by etching the surface of the metal wire so that the core remains. According to this configuration, the cross-sectional area ratio of the core portion as an anode can be arbitrarily and easily adjusted while ensuring the continuity between the core portion and the porous portion. By adjusting the ratio of the core portion to the total of the core portion and the porous portion in the cross-sectional area (that is, the cross-sectional area ratio), the magnitude of the capacitance and the degree of contact with the anode terminal can be adjusted. For example, if this ratio is large, the contact surface of the core portion with the anode terminal becomes large. That is, the resistance at the electrical connection portion is low, which is advantageous for passing a large current, for example. Further, since the contact area between the core portion and the plating film can be further secured, for example, it has an advantage in long-term durability. Although these are merely examples, it is preferable to arbitrarily adjust the cross-sectional area ratio of the core portion according to various requirements.

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

In the solid electrolytic capacitor according to the present invention, if a lower ESR (equivalent series resistance) and a larger capacitance 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 second feature of the present invention is that the cathode terminal is made of a flat metal plate in contact with a part of the peripheral surface of the functional layer on the cathode side. The metal plate is superior in heat dissipation to the printed circuit board and the resin plate. Further, as compared with the printed circuit board, it is not necessary to form a through-hole conductor or a via conductor for wiring the capacitor element and the mounting side terminal, and the metal plate provides a conductive path on the entire surface, so that it is conductive. The route length can be shortened. Further, even if the metal plate is thin, it is excellent in terms of strength, which is advantageous for reducing the height of the solid electrolytic capacitor. Further, the metal plate is cheaper than the printed circuit board, which is advantageous for reducing the cost of the solid electrolytic capacitor.

According to the present invention, a pair of anode terminals are arranged on a pair of end faces of a main body, and both end faces of a core portion of a through conductor are covered with a pair of anode terminals and brought into contact with each other. Therefore, the length of the conductive path 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 improved.

Further, as described above, according to the present invention, both end faces of the core portion of the through conductor are covered with a pair of anode terminals and brought into contact with each other with a pair of anode terminals, so that this contact is relatively large. It can be surface contact between wide surfaces. Therefore, the resistance at the electrical connection portion between the core portion of the through conductor and the anode terminal can be suppressed to a low level. Therefore, a large current can be passed through the solid electrolytic capacitor.

Further, according to the present invention, the anode terminal that does not contribute to the capacitance formation is arranged on the end face of the main body, and the end face of the core portion of the through conductor is in direct contact with the anode terminal, which contributes to the capacitance formation. The ratio of the non-anode members to the total product is relatively low, and the volumetric efficiency is high. Therefore, it is suitable for small size and large capacity. In addition, the noise removal performance in the frequency band due to the capacitance can be improved. Therefore, according to the present invention, the noise removal performance can be improved in a wide frequency band including a high frequency band due to parasitic inductance and a frequency band due to capacitance.

Further, according to the present invention, the functions of the two parts of the porous sintered body 2 and the anode wire 3 in the solid electrolytic capacitor 1 described in Patent Document 1 and shown in FIG. 8 are defined as the core portion and the porous portion. Since it can be carried by a single component called a penetrating conductor having a and, the number of components can be reduced and the cost can be reduced accordingly.

It is a perspective view which shows the appearance of the solid electrolytic capacitor 21 by 1st Embodiment of this invention. It is sectional drawing which follows the line II-II of FIG. It is a bottom view of the solid electrolytic capacitor 21 shown in FIG. It is sectional drawing which follows the line IV-IV of FIG. It is sectional drawing which shows the part V of FIG. 2 in an enlarged manner. It is for demonstrating the 2nd Embodiment of this invention, and is the cross-sectional view which shows the part VI of FIG. 2 enlarged and schematically. It is a front view center cross-sectional view which shows the solid electrolytic capacitor 21a by 3rd Embodiment of this 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 diagram of the solid electrolytic capacitor 1 shown in FIG.

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

The solid electrolytic capacitors 21 are arranged on a rectangular parallelepiped main body 25 having a pair of end faces 22 and 23 facing each other and a bottom surface 24 adjacent to the end faces 22 and 23, and a pair of end faces 22 and 23 of the main body 25. It includes a pair of anode terminals 26 and 27 and a cathode terminal 28 on the bottom surface 24 of the main body 25.

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

The capacitor element 30 includes a linear through conductor 31 made of a valve acting metal. As the valve acting metal constituting the through 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. An aluminum wire is preferably used as the through conductor 31 because it is inexpensive and easily available.

The through conductor 31 is composed of a core portion 32 extending in the axial direction of the through conductor 31 and a porous portion 33 that covers the peripheral surface of the core portion 32 and has a large number of pores. The perforated portion 33 is formed by, for example, etching the peripheral surface of a through conductor 31 made of an aluminum wire to roughen the peripheral surface. As schematically shown in FIG. 5, the porous portion 33 is formed with a large number of pores 34 having openings facing outward. In addition, in FIG. 2 and FIG. 4, the perforated portion 33 is shown by a shaded area sandwiched by a thick dotted line.

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 on 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 peripheral surface of the pores 34 of the porous portion 33.

The capacitor element 30 further includes a cathode-side functional layer 36 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 on the conductive polymer layer 37, and a silver layer 39 on the carbon layer 38. As shown in FIG. 5, the conductive polymer layer 37 is provided so as to fill at least a part of the pores 34 of the porous portion 33. As a result, the conductive polymer layer 37 and the dielectric layer 35 can be brought into contact with each other over a wide area. The carbon layer 38 and the silver layer 39 of the cathode side functional layer 36 function as the 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 composed 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 a conductive adhesive 40 (see FIG. 4). The cathode terminal 28 is made of a metal plate and is in contact with a part of the peripheral surface of the cathode side functional layer 36 .

Of the peripheral surface of the through conductor 31, the portion other than the portion connected to the cathode terminal 28 is sealed with the sealing material 29. Both end faces of the core portion 32 are exposed from the sealing material 29 in a state of extending in a direction perpendicular to the axial direction of the through conductor 31, and on each of the pair of end faces 22 and 23 of the main body 25, A pair of anode terminals 26 and 27 are covered and in contact with each other, respectively. As shown in FIG. 2, the anode terminals 26 and 27 are formed on the end face of the core portion 32 of the through conductor 31, for example, a metal such as nickel, zinc, copper, tin, gold, silver, palladium or lead, or It is composed of a plating film containing an alloy containing at least one of these metals, or a conductive resin film containing at least one of silver, copper, nickel, tin and palladium as a conductive component. Alternatively, the 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 should be noted that contacting the anode terminals 26 and 27 with, for example, a metal piece or a metal lead material and connecting them by laser welding, resistance welding, ultrasonic welding, etc. is caused by mechanical damage, contact variation, or the like. This is not a preferable form because it contributes to the occurrence of defects.

An electrically insulating member 43 made of an electrically insulating resin is arranged between the cathode side functional layer 36 and the anode terminals 26 and 27. Thereby, the electrical insulation state between the cathode side functional layer 36 and the anode terminals 26 and 27 can be surely realized. In this embodiment, the perforated portions 33 are removed from both ends of the through conductor 31, the core portion 32 is exposed, and then the electrically insulating member 43 is provided so as to be in contact with the core portion 32. That is, the perforated portion 33 does not exist in the electrically insulating member 43.

As a second embodiment of the present invention, as shown in FIG. 6, the electrical insulating member 43 fills the pores 34 in the porous portion 33 at the portion where the electrical insulating member 43 is in contact with the core portion 32. It may be provided as follows. That is, the perforated portion 33 exists in the electrically insulating member 43.

In either of the two cases described above, the electrically insulating member 43 is in contact with the core portion 32. According to this configuration, since the anode terminals 26 and 27 are formed, it is possible to prevent the inconvenience that the plating solution permeates and remains in the porous portion 33, for example, when wet plating is applied.

The sealing material 29 contains a resin. The sealing material 29 may contain a filler such as alumina or silica or a magnetic material in addition to the resin. When the sealing material 29 contains the above filler, the mechanical strength and workability of the sealing material 29 can be adjusted. Further, the heat shrinkage can be adjusted by selecting a filler having a desired coefficient of linear expansion. When the sealing material 29 contains a magnetic material, the impedance of the capacitor can be intentionally increased. For example, antiresonance may occur when a plurality of capacitors having low impedance are mounted in parallel and used. At this time, if the sealing material contains a magnetic material, antiresonance can be suppressed. As the magnetic material, for example, iron powder, iron-containing alloy powder, or magnetic powder such as ferrite powder is used. The magnetic material may be a mixture of two or more powders having different particle sizes or different compositions. As described above, 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, a pair of anode terminals 26 and 27 are arranged on a pair of end faces 22 and 23 of the main body 25, and both end faces of the core portion 32 of the through conductor 31 are a pair of anodes. Since the terminals 26 and 27 are covered and brought into contact with the pair of anode terminals 26 and 27, respectively, the length of the conductive path on the anode terminals 26 and 27 can be shortened. Therefore, in the equivalent circuit of FIG. 9, the parasitic inductance corresponding to the parasitic inductances L2 and L3 generated in the conductive paths on the anode terminals 4 and 5 side can be reduced, and the solid electrolytic capacitor 21 in the high frequency band (ωL) can be reduced. The noise removal performance can be improved.

The anode terminals 26 and 27 that do not contribute to volume formation are arranged 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. Therefore, the ratio of the members that do not contribute to the capacitance formation to the total product is relatively low, and the volumetric 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) due to 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 a high frequency band due to inductance and a frequency band due to capacitance.

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

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

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

As the through conductor 31, a porous portion 33 is formed by being subjected to an etching treatment, and a columnar column having a dielectric layer 35 formed by anodic oxidation, for example, having a diameter of 0.8 mm and a length of 2.0 mm is provided. Prepare the aluminum wire. Here, as an example, in order to measure the withstand voltage of the dielectric layer 35 formed on the through conductor 31, a constant current of 0.35 mA / cm ² was applied for 180 seconds in an aqueous ammonium adipate solution at room temperature. , 60V withstand voltage was recognized. In this 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 rest is the porous portion 33. Therefore, the diameter ratio of 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 the aluminum wire and dried to form an electrically insulating member 43 having a thickness of, for example, 0.05 mm. The electrically insulating member 43 is in a state of filling the pores 34 in the porous portion 33. The porous portion 33 may be removed before applying the electrically insulating resin.

Next, 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 arranged, and then the carbon layer 38 and the silver layer 39 are used as cathodes. To form. The conductive polymer layer 37 is chemically oxidatively polymerized by alternately applying a reaction solution composed of a monomer which is a precursor of a polymer and a dopant and an oxidizing agent to carry out a polymerization reaction, or electrochemically in the reaction solution. It can be formed by electrolytic polymerization in which a polymerization reaction is carried out, or a method in which a solution in which a conductive polymer having exhibited conductivity is dissolved or dispersed in an arbitrary solvent is applied.

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

As a result of measuring the capacitance of the capacitor element 30 thus obtained at 120 Hz using an LCR meter, it was 1.0 μF. Next, a voltage of 25 V was applied to the element 30 for 1 minute, and the leakage current was measured. As a result, it was 2.1 nA. The leakage current was extremely small and good (corresponding to about 0.0001 CV when converted to CV).

In the above-mentioned steps, since the through conductor 31 is columnar, the formability of the conductive polymer layer 37, the carbon layer 38, and the silver layer 39 is good. Further, if the penetrating conductor 31 is cylindrical, the entire circumferential surface thereof can be used as the capacitance appearance portion.

Next, the cathode side functional layer 36 on the through conductor 31 is bonded to a metal plate to be a cathode terminal 28 having a thickness of 0.1 mm and a width of 1.2 mm with a conductive adhesive 40, and then the outside of the cathode terminal 28. The resin is molded so that the surface facing the surface and both end surfaces of the through conductor 31 are exposed to form the sealing material 29. The exposure of both end faces 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 the formation of the anode terminals 26 and 27.

Since the penetrating conductor 31 is cylindrical at the time of molding the sealing material 29, the external stress applied to the penetrating conductor 31 is advantageously dispersed, and a situation in which the penetrating conductor 31 is damaged can be advantageously avoided. Damage causes problems such as increased leakage current. Further, since the through conductor 31 is cylindrical, the filling property of the sealing material 29 is excellent. For example, a gap is unlikely to occur between the capacitor element 30 and the sealing material 29, which is high due to the sealing material 29. A package effect can be obtained.

Next, the anode terminals 26 and 27 are formed so as to be connected to both end faces of the through conductor 31 exposed from the sealing material 29. For the formation of the anode terminals 26 and 27, for example, a plating film is formed, followed by a conductive resin film having a thickness of, for example, 0.01 mm. Alternatively, due to the formation of the anode terminals 26 and 27, only the plating film may be formed, or only the conductive resin film may be formed.

As described above, the solid electrolytic capacitor 21 having external dimensions of, for example, 2.02 mm (longitudinal dimension) × 1.22 mm (width direction dimension) × 1.22 mm (height direction dimension) is completed. As an example, the solid electrolytic capacitor 21 thus obtained was measured with a capacitance of 120 Hz using an LCR meter and found to be 1.0 μF. Next, a voltage of 25 V was applied to the capacitor for 1 minute, and the leakage current was measured. As a result, it was 2.0 nA. No increase in leakage current was observed, which was good.

Next, with reference to FIG. 7, the solid electrolytic capacitor 21a according to the third embodiment of the present invention will be described. FIG. 7 is a cross-sectional view at the center of the front view, but in FIG. 7, the elements corresponding to the elements shown in FIG. 2 are designated by the same reference numerals, and redundant description will be omitted.

The solid electrolytic capacitor 21a 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 with a sealing material 29 in a side-by-side arrangement.

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 core portions 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 layer 39 included in the cathode side functional layer 36 in each of the two capacitor elements 30 is electrically connected to each other. It is provided along the bottom of the.

In this way, 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, a lower ESR and a larger capacitance can be realized as compared with the solid electrolytic capacitor 21 described above.

Although the present invention has been described above in relation to the illustrated embodiments, these embodiments are exemplary and it is possible to partially replace or combine configurations between different embodiments. I will point out.

21,21a Solid Electrolytic Capacitor 22,23 End Face 24 Bottom 25 Main Body 26, 27 Anode Terminal 28 Cathode Terminal 29 Encapsulant 30 Capacitor Element 31 Through Conductor 32 Core 33 Porous 34 Pore 35 Dielectric Layer 36 Cathode Side Functional Layer 37 Conductive polymer layer 38 Carbon layer 39 Silver layer 43 Electrical insulation member

Claims (10)

A rectangular parallelepiped body having a pair of end faces facing each other and a bottom surface adjacent to the end faces,
A pair of anode terminals arranged on the pair of end faces of the main body,
The cathode terminal on the bottom surface of the main body and
With
The main body
Encapsulant containing resin and
The capacitor element covered with the sealing material and
With
The capacitor element is
A columnar through conductor made of valvening metal and
A dielectric layer on the peripheral surface of the through conductor and
A cathode-side functional layer on the dielectric layer and electrically connected to the cathode terminal.
With
The penetrating conductor is composed of a core portion extending in the axial direction of the penetrating conductor and a porous portion that covers the peripheral surface of the core portion and has a large number of pores.
The dielectric layer is formed along the inner peripheral surface of the pores of the porous portion.
The peripheral surface of the penetrating conductor is sealed with the sealing material except for the portion connected to the cathode terminal, and both end faces of the core portion are perpendicular to the axial direction of the penetrating conductor. while extending in a direction are exposed from the sealing material, on each of the end faces of said pair of said main body, and respectively covered and in contact with the anode terminal of said pair,
The cathode terminal is made of a flat metal plate in contact with a part of the peripheral surface of the cathode side functional layer.
Solid electrolytic capacitor. The solid electrolytic capacitor according to claim 1, wherein the cathode-side functional layer includes a conductive polymer layer that fills at least a part of the pores of the porous portion. The solid electrolytic capacitor according to claim 1 or 2, further comprising an electrically insulating member arranged 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 the electrically insulating member fills the pores in the porous portion at a portion where the electrically insulating member is in contact with the core portion. The solid electrolytic capacitor according to claim 4, wherein the porous portion does not exist in a portion where the electrically insulating member is in contact with the core portion. The solid electrolytic capacitor according to any one of claims 1 to 6, wherein the anode terminal includes a plating film. The solid electrolytic capacitor according to any one of claims 1 to 7, wherein the anode terminal includes a conductive resin film. The solid electrolytic capacitor according to any one of claims 1 to 8, wherein the perforated portion comprises an etching-treated portion formed on the peripheral surface of the linear through conductor. The solid electrolysis according to any one of claims 1 to 9, wherein the main body includes a plurality of the capacitor elements, and the plurality of the capacitor elements are connected in parallel via the anode terminal and the cathode terminal. Capacitor .

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