Low inductance electrolytic capacitor

Abstract

A capacitor capable of exhibiting good electrical properties under a variety of conditions is provided. The capacitor includes a capacitor element including a sintered porous anode body, a dielectric covering the anode body, and a solid electrolyte covering the dielectric and including a conductive polymer. The capacitor also includes a plurality of exposed anode lead portions electrically connected to respective anode terminations, and a planar cathode termination electrically connected to the solid electrolyte.

Description

[Technical Field]

[0001] Cross-references to related applications This application claims the benefit of filing U.S. Provisional Patent Application No. 63 / 082,055, filed September 23, 2020, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Decoupling capacitors are often used to manage noise problems that occur in circuit applications. They provide a stable local charge source necessary for switching and refreshing logic gates used in various digital circuits. However, decoupling capacitors now must be able to operate at lower voltages and higher currents, and to function at the levels required for diverse applications in the current situation, these capacitors require performance characteristics such as lower equivalent series resistance (ESR), higher capacitance, and lower inductance (or ESL). In particular, as switching speeds in electronic circuit applications increase, the need for reduced inductance to improve system performance has become a serious limitation. Solid electrolytic capacitors (e.g., tantalum capacitors) are typically manufactured by pressing metal powder (e.g., tantalum) around metal lead wires, sintering the compressed portion, anodic oxidation of the sintered anode, and then coating it with a solid electrolyte. Conductive polymers are often used as solid electrolytes due to their advantageous low equivalent series resistance and "non-combustion / non-ignition" failure mode. However, while solid electrolytic capacitors offer clear advantages in terms of ESR, they have so far failed to withstand high-frequency applications or exhibit the low inductance required for decoupling and high-speed switching. Therefore, there is now a need for improved performance solid electrolytic capacitors.

SUMMARY OF THE INVENTION

MEANS FOR SOLVING THE PROBLEM

[0003] According to one embodiment of the present invention, there is provided a solid electrolytic capacitor including a capacitor element comprising a sintered anode body, a dielectric covering the anode body, and a solid electrolyte covering the dielectric, wherein the solid electrolyte contains a conductive polymer, the capacitor element defines opposing first and second ends and opposing upper and lower surfaces; a first exposed anode lead portion extending from the first end of the capacitor element; a first anode terminal electrically connected to the first exposed anode lead portion; a second exposed anode lead portion extending from the second end of the capacitor element; a second anode terminal spaced from the first anode terminal and electrically connected to the second exposed anode lead portion; and a planar cathode terminal positioned adjacent to the lower surface of the capacitor element and electrically connected to the solid electrolyte.

[0004] Other features and aspects of the present invention are described in further detail below.

[0005] A complete and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in more specific detail in the remainder of the specification, which makes reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] [Figure 1] FIG. 1A is a side view of one embodiment of an anode body according to the present invention.

[0007] FIG. 1B is a side view of one embodiment of an anode body according to the present invention.

[0008] FIG. 1C is a side view of one embodiment of an anode body according to the present invention. [Figure 2]A side view of an embodiment of a capacitor according to the present invention. [Figure 3] A top view of the capacitor of FIG. 2. [Figure 4] A diagram showing an exemplary equivalent circuit used in Example 1. [Figure 5] A graph showing impedance versus frequency for the case of Example 1 compared with a standard capacitor. [Figure 6] A graph showing the S21 parameter measured by modeling over a wide range of frequencies for the case of Example 1.

Best Mode for Carrying Out the Invention

[0009] It should be understood by those skilled in the art that this description is merely an explanation of exemplary embodiments and is not intended to limit a broader aspect of the present invention, and that a broader aspect of the present invention is exemplified.

[0010] Generally speaking, the present invention is directed to a capacitor capable of exhibiting good electrical characteristics under various conditions. This capacitor includes a capacitor element including a sintered porous anode body, a dielectric covering the anode body, and a solid electrolyte covering the dielectric and including a conductive polymer. The capacitor element includes opposing first and second ends, as well as opposing upper and lower surfaces. This capacitor also includes a plurality of anode leads electrically connected to individual anode terminals, and a planar cathode terminal positioned adjacent to the lower surface of the capacitor element and electrically connected to the solid electrolyte.

[0011] Selective control over specific configurations of the capacitor elements and terminals allows the resulting capacitors to exhibit low ESL values, such as less than about 1 nanohenry, less than about 750 picohrenry in some embodiments, less than about 350 picohrenry in some embodiments, less than about 1 femtohenry to about 100 picohrenry in some embodiments, and less than about 50 femtohenry to about 10 picohrenry in some embodiments. Low ESL values ​​can also be characterized by low impedance values, which reflect parasitic inductance. Impedance can be, for example, less than about 1 ohm, less than about 0.8 ohms in some embodiments, less than about 0.6 ohms in some embodiments, and less than about 1 megaohm to about 0.3 ohms in some embodiments. Such low ESL (e.g., impedance) can also exhibit a wide frequency range, such as 1 kHz to about 100 MHz, less than 100 kHz to about 100 MHz in some embodiments, and less than about 1 MHz to about 100 MHz in some embodiments. Minimizing parasitic inductance over a wide frequency range can contribute to good performance, particularly good decoupling performance, especially under high-speed transient conditions. In addition to exhibiting low ESL values, this capacitor can also exhibit low ESR values ​​such as approximately 800 megaohms or less, approximately 600 megaohms or less in some embodiments, approximately 500 megaohms or less in some embodiments, approximately 350 megaohms or less in some embodiments, approximately 0.01 to approximately 250 megaohms in some embodiments, and approximately 0.1 to approximately 150 megaohms in some embodiments, when measured at an operating frequency of 100 kHz and a temperature of 23°C.

[0012] In particular, low ESR and ESL values ​​can remain stable even at high temperatures and / or high humidity levels. For example, the capacitor can exhibit ESR and / or ESL values ​​within the above range even after being exposed for a considerable period to temperatures above approximately 80°C, in some embodiments approximately 85°C to approximately 180°C, and in some embodiments approximately 850°C to approximately 150°C (e.g., approximately 85°C, 105°C, 125°C, or 150°C), and / or relative humidity levels above approximately 40%, in some embodiments approximately 45%, in some embodiments approximately 50%, and in some embodiments approximately 70% (e.g., approximately 85% to 100%). Relative humidity can be determined, for example, in accordance with ASTM E337-02, Method A (2007). The duration of exposure to high temperature and / or high humidity levels can be approximately 100 hours or more, in some embodiments approximately 150 to approximately 3,000 hours, and in some embodiments approximately 200 to approximately 2,500 hours (e.g., 250, 500, 750, or 1,000 hours). For example, the ESR of a capacitor after 500 hours of exposure to high temperature (e.g., approximately 85°C) and / or high humidity levels (e.g., approximately 85%), measured at an operating frequency of 100 kHz and a temperature of 23°C, may be approximately 1,500 megaohms or less, in some embodiments approximately 1,000 megaohms or less, in some embodiments approximately 800 megaohms or less, in some embodiments approximately 600 megaohms or less, in some embodiments approximately 0.01 to approximately 500 megaohms, and in some embodiments approximately 0.1 to approximately 200 megaohms. Similarly, the ratio of the ESR of a capacitor after 500 hours of exposure to high temperatures (e.g., about 85°C) and / or high humidity levels (e.g., about 85%) to the capacitor's initial DCL (e.g., about 23°C) may be about 10 or less, about 5 or less in some embodiments, about 3 or less in some embodiments, about 2 or less in some embodiments, and about 0.9 to about 1.5 in some embodiments.

[0013] The resulting capacitor has the ability to achieve a combination of low ESL and ESR values, thus positioning it uniquely to enable robust broadband decoupling and high-speed switching. For example, a single capacitor according to the present invention may be used to replace multiple low capacitance or limiting frequency decoupling capacitors, thereby further improving miniaturization by utilizing a narrower space, such as having an even smaller height.

[0014] The capacitor can exhibit excellent DC power filtering, exemplified by its superior attenuation over a wide frequency range. As is well known in the art, insertion loss measures the power transmission between the two terminals, with gain indicating an increase in power and attenuation indicating a decrease in power between the two terminals. Therefore, this capacitor exhibits high attenuation over a wide frequency range, enabling good filtering across a wide frequency range. For example, this capacitor exhibits approximately 15 dB or more, approximately 25 dB or more in some embodiments, approximately 30 dB or more in some embodiments, approximately 35 dB to approximately 70 dB in some embodiments, and approximately 50 dB to approximately 70 dB in some embodiments, resulting in approximately attenuation (S 21 The parameters can be shown. Such attenuation may be shown over a wide frequency range. For example, at low frequencies in the range of approximately 0.1 MHz to approximately 500 MHz, and in some cases, approximately 1 MHz to approximately 100 MHz, the capacitor exhibits attenuation of approximately 40 dB or more, in some embodiments approximately 50 dB or more, in some embodiments approximately 55 dB or more, and in some embodiments approximately 60 dB to approximately 70 dB (S 21 The parameters can be shown. Similarly, at high frequencies in the range of approximately 500 MHz to approximately 10 GHz, and in some cases, approximately 1 GHz to approximately 5 GHz, this capacitor provides attenuation of approximately 20 dB or more, in some embodiments approximately 25 dB or more, in some embodiments approximately 30 dB or more, and in some embodiments approximately 30 dB to approximately 60 dB (S 21The parameters can be shown. In particular, such attenuation makes it easy to use this capacitor in DC power filtering applications. Furthermore, this capacitor can perform consistently over a wide temperature range. For example, in one embodiment, the capacitor can vary by about 5 dB or less over a large temperature range, such as temperature changes of about 25°C or higher, in some embodiments about 50°C or higher, and in some embodiments about 70°C or higher.

[0015] This capacitor can also exhibit other beneficial electrical properties. For example, this capacitor can exhibit low leakage current ("DCL") over a variety of conditions. Furthermore, after being subjected to an applied voltage (e.g., 16 volts) at a temperature of approximately 23°C for a certain period (e.g., approximately 30 minutes to approximately 20 hours, approximately 1 hour to approximately 18 hours in some embodiments, and approximately 4 hours to approximately 16 hours), this capacitor can exhibit a DCL of approximately 10 microamperes ("μA") or less, approximately 5 μA or less in some embodiments, approximately 1 μA or less in some embodiments, and approximately 0.01 to approximately 5 μA in some embodiments. In one embodiment, after exposure to high temperature (e.g., approximately 85°C) and / or high humidity levels (e.g., approximately 85%) for 500 hours, the DCL of the capacitor may be approximately 10 μA or less, approximately 8 μA or less in some embodiments, approximately 6 μA or less in some embodiments, and approximately 0.1 to approximately 5 μA in some embodiments. Similarly, the DCL ratio of this capacitor after 500 hours of exposure to high temperatures (e.g., about 85°C) and / or high humidity levels (e.g., about 85%) compared to the initial DCL (e.g., about 23°C) may be about 20 or less, about 15 or less in some embodiments, about 10 or less in some embodiments, about 5 or less in some embodiments, and about 0.9 to about 4 in some embodiments. This capacitor also has a DCL of about 30 nanofarads per square centimeter ("nF / cm") when measured at a frequency of 120 Hz and a temperature of 23°C. 2 In some embodiments, the temperature is approximately 100 nF / cm². 2 In some embodiments described above, the values ​​are approximately 200 to 3,000 nF / cm². 2, and in some embodiments, can exhibit a dry capacitance of about 400 to about 2,000 nF / cm 2 The actual capacitance can vary, such as from about 10 μF to about 1,000 μF, in some embodiments from about 50 μF to about 500 μF, and in some embodiments from about 60 μF to about 250 μF. Similar to the DCL value and the ESR value, the capacitance can also remain in a stable state within the above range of high temperature and / or high humidity levels. In one embodiment, for example, the ratio of the capacitance value of the capacitor after being exposed to a high temperature (e.g., about 85°C) and / or high humidity level (e.g., about 85%) for 500 hours to the initial capacitance value (e.g., about 23°C) of this capacitor can be about 3.0 or less, in some embodiments about 2.0 or less, in some embodiments about 1.8 or less, in some embodiments about 1.6 or less, and in some embodiments can be from about 0.9 to about 1.3.

[0016] It is also considered that the dielectric tangent of this capacitor can be maintained at a relatively low level. The dielectric tangent generally refers to the losses generated in a capacitor and is usually expressed as a percentage of ideal capacitor performance. For example, the dielectric tangent of this capacitor, when measured at a frequency of 120 Hz, is usually about 250% or less, in some embodiments about 200% or less, and in some embodiments is from about 1% to about 180%.

[0017] Various embodiments of the present invention will be described in further detail hereinafter.

[0018] I. Capacitor Element A. Anode Body The anode body is formed from a powder containing a valve metal (i.e., a metal capable of oxidation), or a compound based on a valve metal such as tantalum, niobium, aluminum, hafnium, titanium, their alloys, their oxides, their nitrides, etc. The specific charge of this powder is usually about 5,000 to about 800,000 microfarads per gram * volts (「μF *It varies with V / g. For example, in certain embodiments, it ranges from approximately 100,000 to approximately 600,000 μF. * V / g, in some embodiments, approximately 120,000 to approximately 500,000 μF * V / g, and in some embodiments, approximately 150,000 to approximately 400,000 μF * High-charge powders having a specific charge of V / g may be used. In other embodiments, about 5,000 to about 100,000 μF * V / g, in some embodiments, approximately 8,000 to approximately 90,000 μF * V / g, and in some embodiments, about 10,000 to about 80,000 μF * Low-charge powders having a specific charge of V / g may be used. As is well known in the art, the specific charge can be obtained by multiplying the capacitance by the anodic oxidation voltage and then dividing this product by the weight of the anodic-oxidized electrode body.

[0019] In one embodiment, for example, the powder is formed from tantalum. If desired, a reduction process can be used in which a tantalum salt (e.g., potassium fluorotantalate (K2TaF7), sodium fluorotantalate (Na2TaF7), tantalum pentachloride (TaCl5), etc.) is reacted with a reducing agent. The reducing agent may be supplied in liquid, gaseous (e.g., hydrogen), or solid form such as a metal (e.g., sodium), metal alloy, or metal salt. In one embodiment, for example, a tantalum salt (e.g., TaCl5) may be heated to a temperature of about 900°C to about 2,000°C, in some embodiments about 1,000°C to about 1,800°C, and in some embodiments about 1,100°C to about 1,600°C, to form a vapor that can be reduced in the presence of a gaseous reducing agent (e.g., hydrogen). Further details of such reduction reactions may be found in WO2014 / 199480 to Maeshima et al. After reduction, the product may be cooled, pulverized, and washed to form a powder.

[0020] The powder may be a free-flowing, finely ground powder containing primary particles. The primary particles of the powder generally have a median size (D50) of about 5 to about 250 nanometers, in some embodiments about 10 to about 200 nanometers, and in some embodiments about 20 to about 150 nanometers, which may be determined by using a laser particle size distribution analyzer from BECKMAN COULTER Corporation (e.g., LS-230) after subjecting the particles to ultrasonic vibration for 70 seconds. The primary particles usually have a three-dimensional granular shape (e.g., with nodes or angles). Such particles usually have a relatively low "aspect ratio" obtained by dividing the average diameter or width of the particles by the average thickness ("D / T"). For example, the aspect ratio of the particles may be about 4 or less, in some embodiments about 3 or less, and in some embodiments about 1 to about 2. In addition to the primary particles, the powder may also contain other types of particles, such as secondary particles formed by the aggregation (or agglomeration) of the primary particles. Such secondary particles may have a median size (D50) of about 1 to about 500 micrometers, and in some embodiments, about 10 to about 250 micrometers.

[0021] Particle agglomeration may be carried out by heating the particles and / or by using a binder. For example, agglomeration may be carried out at temperatures of about 0°C to about 40°C, in some embodiments about 5°C to about 35°C, and in some embodiments about 15°C to about 30°C. Similarly, suitable binders may include, for example, poly(vinyl butyral); poly(vinyl acetate); poly(vinyl alcohol); poly(vinylpyrrolidone); cellulose polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose and methylhydroxyethylcellulose; atactic polypropylene, polyethylene; polyethylene glycol (e.g., Carbowax from Dow Chemical Co.); polystyrene, poly(butadiene / styrene); polyamides, polyimides and polyacrylamides, high molecular weight polyethers; copolymers of ethylene oxide and propylene oxide; fluoropolymers such as polytetrafluoroethylene, polyvinylidene fluoride and fluoroolefin copolymers; acrylic polymers such as sodium polyacrylate, poly(lower alkyl acrylate), poly(lower alkyl methacrylate) and copolymers of lower alkyl acrylate and methacrylate; as well as fatty acids and waxes such as stearic acid and other soaps, vegetable waxes, and microwaxes (purified paraffin). If desired, the powder may also be doped with a sinter retardant in the presence of a dopant such as acidic water (e.g., phosphoric acid). The amount of dopant added depends in part on the surface area of ​​the powder, but is usually present in amounts of approximately 200 parts per million ("ppm") or less. The dopant may be added before agglomeration, during agglomeration, and / or after agglomeration. The powder may also be subjected to one or more deoxygenation treatments. For example, the powder may be exposed to a getter material (e.g., magnesium), such as that described in U.S. Patent No. 4,960,471.The temperature at which the powder is deoxygenated can vary, but is typically in the range of approximately 700°C to 1,600°C, approximately 750°C to 1,200°C in some embodiments, and approximately 800°C to 1,000°C in some embodiments. The total deoxygenation time can be in the range of approximately 20 minutes to 3 hours.

[0022] The resulting powder has certain characteristics that enhance its ability to form capacitor nodes. For example, the powder is approximately 0.5 to 10.0 m 2 / g, in some embodiments, about 0.7 to about 5.0m 2 / g, and in some embodiments, about 2.0 to about 4.0m 2 It typically has a specific surface area of ​​0.1 to 0.8 grams per cubic centimeter (g / cm³). Similarly, the bulk density of the powder is approximately 0.1 to 0.8 grams per cubic centimeter (g / cm³). 3 ), in some embodiments, about 0.2 to about 0.6 g / cm³ 3 , and in some embodiments, about 0.4 to about 0.6 g / cm³ 3 This could be the case.

[0023] Once the powder is formed, it is then compressed or pressed, generally using any conventional powder press device, to form pellets. For example, a press mold may be used, which is a single-station compression press including a die and one or more pressers. Alternatively, an anvil-type compression press mold may be used, which uses only a die and a single lower presser. Single-station compression press molds are available in several basic types, such as cam, toggle / knuckle, and eccentric / crank presses, with various capabilities including single-acting, dual-acting, floating die, movable platen, opposing ram, shaft, impact, high-temperature press, printing, or sizing. The powder is typically about 0.5 to about 20 g / cm³. 3 In some embodiments, approximately 1 to approximately 15 g / cm³ 3 , and in some embodiments, about 2 to about 10 g / cm³ 3 It is pressed down to this density.

[0024] The binder may be removed after pressing by heating the pellet under vacuum for several minutes at a specific temperature (e.g., about 150°C to about 500°C). Alternatively, the binder may also be removed by contacting the pellet with an aqueous solution, such as described in U.S. Patent No. 6,197,252 to Bishop et al. After the binder has been removed, the anode body may be subjected to an optional deoxygenation process. In one embodiment, for example, the deoxygenation process includes exposing the anode body to a getter material (e.g., magnesium, titanium, etc.) capable of removing oxygen from the anode body by chemical reaction, adsorption, etc. More specifically, the anode body is first inserted into a confinement (e.g., a tantalum box) which also contains the getter material. The atmosphere inside this confinement is typically an inert atmosphere (e.g., argon gas). To initiate deoxygenation, the atmosphere inside the confinement is heated to a temperature sufficient to melt and / or vaporize the getter material and deoxygenate the anode body. The temperature may vary depending on the specific charge of the anode powder, but is typically in the range of about 700°C to 1,200°C, about 750°C to 1,100°C in some embodiments, and about 800°C to 1,000°C in some embodiments. The total deoxygenation time can be in the range of about 20 minutes to 3 hours. This may be carried out in one or more steps. Once deoxygenation is complete, the getter material usually vaporizes and forms precipitates on the walls of the closure. To ensure the removal of the getter material, the anode body may also be subjected to one or more acid leaching steps using solutions of nitric acid, hydrofluoric acid, hydrogen peroxide, sulfuric acid, water, or combinations thereof.

[0025] The resulting anode body has a relatively low oxygen content. For example, the anode body may have an oxygen content of approximately 5,500 ppm or less, in some embodiments approximately 5,000 ppm or less, and in some embodiments approximately 500 to 4,500 ppm. The oxygen content can be measured by a LECO oxygen analyzer and includes oxygen in the natural oxides on the tantalum surface and bulk oxygen in the tantalum particles. The bulk oxygen content is controlled by the periodicity of the tantalum crystal lattice, which increases linearly with increasing oxygen content in tantalum until the solubility limit is reached. This method is described in "Critical Oxygen Content In Porous Anodes Of Solid Tantalum Capacitors" by Pozdeev-Freeman et al. in the Journal of Materials Science: Materials In Electronics, Vol. 9 (1998), pp. 309-311, where X-ray diffraction analysis (XRDA) was used to measure the periodicity of the tantalum crystal lattice. While oxygen in sintered tantalum anodes may be limited to a thin natural surface oxide, bulk tantalum is substantially oxygen-free.

[0026] After optional deoxygenation, the anode body can be sintered to form a porous, integrated mass. The anode body is typically sintered at a temperature of about 700°C to about 1,600°C, in some embodiments about 800°C to about 1,500°C, and in some embodiments about 900°C to about 1,200°C, for about 5 minutes to about 100 minutes, and in some embodiments about 8 minutes to about 15 minutes. This may be carried out in one or more steps. If desired, sintering may be carried out in an atmosphere that restricts the movement of oxygen atoms to the anode. For example, sintering may be carried out in a vacuum, an inert gas, or a reducing atmosphere such as hydrogen. The reducing atmosphere can be at a pressure of about 10 Torr to about 2000 Torr, in some embodiments about 100 Torr to about 1000 Torr, and in some embodiments about 100 Torr to about 930 Torr. A mixture of hydrogen and other gases (e.g., argon or nitrogen) may also be used. As stated above, the sintering of the anode body is generally carried out after any of the optional deoxygenation processes. However, it should be understood that the anode body may also undergo one or more pre-sintering steps before oxidation to help achieve the desired degree of raw strength in the case of the deoxygenation process. Such pre-sintering steps may be carried out under the same conditions as the sintering process carried out after deoxygenation, or under different conditions. For example, pre-sintering may be carried out in one or more steps at a temperature of about 700°C to about 1,600°C, in some embodiments about 800°C to about 1,500°C, and in some embodiments about 900°C to about 1,200°C, for about 5 minutes to about 100 minutes, and in some embodiments about 8 minutes to about 15 minutes. Pre-sintering may also be carried out in a vacuum, an inert gas, a reducing atmosphere such as hydrogen, as described above.

[0027] As shown above, the capacitor also includes a plurality of anode lead portions electrically connected to individual anode terminals. The anode lead portions may be formed as portions of a single anode lead (e.g., opposing ends) or as portions of individual anode leads. The anode leads can have any desired shape and size and may be in the form of wires, sheets, etc. Typically, the anode leads extend longitudinally from the anode body and are formed from any conductive material such as tantalum, niobium, aluminum, hafnium, titanium, and their conductive oxides and / or nitrides. The connection of the leads to the anode body can be done using any known technique, such as welding one or more leads to the body or fitting one or more anode leads into the anode body during formation (e.g., before compression and / or sintering).

[0028] Referring to Figure 1A, one embodiment of the anode body 10 is shown, having a first anode lead 12 with a recessed portion 24 positioned within the anode body, and an exposed first anode lead portion 26 extending from a first end 16 of the anode body 10. Similarly, a second exposed anode lead portion 14 is connected to a second end 18 of the anode body 10 (e.g., by a joint 20). As shown in Figure 1A, the second exposed anode lead portion 14 is formed as part of an isolated second anode lead extending from the second end 18 of the anode body. Naturally, as shown in Figure 1C, the first exposed anode lead portion 26 and the second exposed anode lead portion 14 can also be defined by opposing portions of a single continuous anode lead 22 extending from both ends 16 and 18 of the anode body 10. Regardless, it is generally preferable that the exposed anode lead portions extend from opposing ends of the anode body on the same plane. Referring again to Figure 1A, a gap may optionally exist between the fitted end of the first anode lead and the end of the anode body, resulting in an electrical connection between the leads of the first and second anodes being provided via the sintered anode body. In Figure 1A, for example, this gap can be defined as the distance "t" between the end 18 of the anode body and the fitted end 28 of the anode lead, which is typically in the range of about 0.2 to about 5 millimeters, in some embodiments about 0.4 to about 4 millimeters, and in some embodiments about 0.5 to about 2 millimeters. The length "l" of the anode can similarly be in the range of about 1.5 to about 6 millimeters, and in some embodiments about 2 to about 5 millimeters. In such embodiments, the ratio of the distance "t" to the length "l" can also be in the range of about 0.1 to about 0.8, in some embodiments about 0.2 to about 0.7, and in some embodiments about 0.3 to about 0.6.

[0029] Another embodiment is shown in Figure 1B, in which the anode body 10 has a first anode lead 12 having a fitted portion 24 positioned within the anode body, and an exposed first anode lead portion 26 extending from the first end 16 of the anode 10. A second anode lead 14 having a fitted portion 32 positioned within the anode body, and an exposed second anode lead portion 34 extending from the second end 18 of the anode body 10. Thus, in this embodiment, the need for a welded portion of the second anode lead is not required. Similar to the above embodiment, a gap "t" may optionally exist between the fitted end of the first anode lead and the fitted end of the second anode lead, and this may be within the above range.

[0030] B. Dielectrics The anode body is coated with a dielectric. The dielectric can be formed by anodic oxidation of the sintered anode body ("anodic oxidation treatment"), resulting in the formation of a dielectric layer on and / or inside the anode body. For example, a tantalum (Ta) anode may be anodic oxidized to tantalum pentoxide (Ta2O5). Typically, anodic oxidation treatment is carried out by first coating the anode with a solution, such as by immersing the anode in an electrolyte. Solvents such as water (e.g., deionized water) are commonly used. To improve ionic conductivity, compounds that can dissociate in the solvent to form ions may be used. Examples of such compounds include acids, such as those described below with respect to electrolytes. For example, an acid (e.g., phosphoric acid) can constitute about 0.01% to about 5% by weight of the anodic oxidation treatment solution, about 0.05% to about 0.8% by weight in some embodiments, and about 0.1% to about 0.5% by weight in some embodiments. Blends of acids may also be used if desired.

[0031] A dielectric layer may be formed by passing an electric current through the anodic oxidation solution. The thickness of the dielectric layer is controlled by the value of the formation voltage. For example, the power supply may initially be set to a constant current mode until the required voltage is reached. After this, the power supply can be switched to a low voltage mode to ensure that the desired dielectric thickness is formed over the entire surface of the anode. Of course, other known methods such as the pulse method or the stepwise constant voltage method may also be used. The formation voltage used during the anodic oxidation process is generally about 20 volts or more, about 30 volts or more, about 35 volts or more, and about 35 to 70 volts at temperatures in the range of about 10°C or more, about 20°C to about 200°C in some embodiments, and about 30°C to about 100°C in some embodiments. The resulting dielectric layer may be formed on the surface of the anode and inside the pores of the anode.

[0032] By selectively controlling a specific method by which the anode body is formed, the resulting capacitor can exhibit high dielectric strength, which can improve capacitance stability. "Dielectric strength" generally refers to the ratio of the capacitor's "resolved voltage" (the voltage at which the capacitor fails, in volts "V") to the dielectric thickness (in nanometers "nm"). Capacitors typically exhibit dielectric strength of about 0.4 V / nm or higher, in some embodiments about 0.45 V / nm or higher, in some embodiments about 0.5 V / nm or higher, in some embodiments about 0.55 to about 1 V / nm, and in some embodiments about 0.6 to about 0.9 V / nm. Capacitors can exhibit relatively high resolution voltages, such as approximately 30 volts or more, in some embodiments approximately 35 volts or more, in some embodiments approximately 50 volts or more, in some embodiments approximately 65 volts or more, in some embodiments approximately 85 volts or more, in some embodiments approximately 90 volts or more, in some embodiments approximately 95 volts or more, and in some embodiments approximately 100 volts to approximately 300 volts, which can be determined by increasing the applied voltage in 3-volt increments until the leakage current reaches 1 mA. The dielectric thickness can generally vary depending on the specific location of the anode body, but the “dielectric thickness” for the purpose of determining dielectric strength is generally considered to be the maximum thickness of the dielectric, which is typically in the range of approximately 50 to approximately 500 nm, in some embodiments approximately 80 to approximately 350 nm, and in some embodiments approximately 100 to approximately 300 nm. The dielectric thickness can be measured using a Zeiss Sigma FESEM at a magnification of 20,000x to 50,000x, in which case the sample is prepared by cutting the finished portion with a plane perpendicular to the longest dimension of the finished portion, and the thickness is measured at the point where the cut is perpendicular to the dielectric layer.

[0033] C. Pre-coat layer Although not strictly necessary, a pre-coat layer can optionally overlay the dielectric containing the organometallic compound. The organometallic compound may have the following general formula:

[0034] [ka]

[0035] In the formula, M is an organometallic atom such as silicon or titanium; R1, R2, and R3 are independently alkyl (e.g., methyl, ethyl, propyl, etc.) or hydroxyalkyl (e.g., hydroxymethyl, hydroxyethyl, hydroxypropyl, etc.), at least one of R1, R2, and R3 is a hydroxyalkyl; n is an integer from 0 to 8, in some embodiments from 1 to 6, and in some embodiments from 2 to 4 (e.g., 3); and X is an organic or inorganic functional group such as glycidyl, glycidyloxy, mercapto, amino, or vinyl.

[0036] In certain embodiments, R1, R2, and R3 may be hydroxyalkyl groups (e.g., OCH3). However, in other embodiments, R1 may be an alkyl group (e.g., CH3), and R2 and R3 may be hydroxyalkyl groups (e.g., OCH3).

[0037] Furthermore, in certain embodiments, M may be silicon, and as a result, the organometallic compound is an organosilane compound such as an alkoxysilane. Suitable alkoxysilanes include, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, and glycidoxymethyltrimethoxysilane. Glycidoxymethyltriethoxysilane, glycidoxymethyl-tripropoxysilane, glycidoxymethyltributoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, β-glycidoxyethyl-tripropoxysilane, β-glycidoxyethyl-tributoxysilane, β-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, α-glycidoxyethyltripropoxysilane, α-glycidoxyethyltributoxysilane γ-glycidoxypropyl-trimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyl-tripropoxysilane, γ-glycidoxypropyltributoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyl-triethoxysilane, β-glycidoxypropyltripropoxysilane, α-glycidoxypropyltributoxysilane, α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane, α-glycid Xyxypropyl-tripropoxysilane, α-glycidoxypropyltributoxysilane, γ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltripropoxysilane, δ-glycidoxybutyl-tributoxysilane, δ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltripropoxysilane, γ-propoxybutyltributoxysilane, δ-glycidoxybutyl-trimethoxysilane,δ-Glycidoxybutyltriethoxysilane, δ-Glycidoxybutyltripropoxysilane, α-Glycidoxybutyltrimethoxysilane, α-Glycidoxybutyltriethoxysilane, α-Glycidoxybutyl-tripropoxysilane, α-Glycidoxybutyltributoxysilane, (3,4-Epoxycyclohexyl)-methyl-trimethoxysilane, (3,4-Epoxycyclohexyl)methyl-triethoxysilane, (3,4-Epoxycyclohexyl)methyltripropoxysilane, (3,4-Epoxycyclohexyl)-methyl-tributoxysilane, (3,4-Epoxycyclohexyl)ethyl-trimethoxysilane, (3,4-Epoxycyclohexyl)ethyl-triethoxysilane, This may include (3,4-epoxycyclohexyl)ethyl tripropoxysilane, (3,4-epoxycyclohexyl)ethyl tripbutoxysilane, (3,4-epoxycyclohexyl)propyltrimethoxysilane, (3,4-epoxycyclohexyl)propyltriethoxysilane, (3,4-epoxycyclohexyl)propyl-tripropoxysilane, (3,4-epoxycyclohexyl)propyl tripbutoxysilane, (3,4-epoxycyclohexyl)butyltrimethoxysilane, (3,4-epoxycyclohexyl)butyltriethoxysilane, (3,4-epoxycyclohexyl)butyl tripropoxysilane, (3,4-epoxycyclohexyl)butyl tripbutoxysilane, etc.

[0038] The specific method by which the precoat layer is applied to the capacitor body can vary as desired. In one particular embodiment, the compound is dissolved in an organic solvent and applied to the portion as a solution by screen printing, dipping, electrophoretic coating, spraying, etc. The organic solvent may vary, but is usually an alcohol such as methanol or ethanol. The organometallic compound can constitute about 0.1% to about 10% by weight of the solution, about 0.2% to about 8% by weight in some embodiments, and about 0.5% to about 5% by weight in some embodiments. The solvent can similarly constitute about 90% to about 99.9% by weight of the solution, about 92% to about 99.8% by weight in some embodiments, and about 95% to about 99.5% by weight in some embodiments. Once applied, the portion can then be dried to remove the solvent and form a precoat layer containing the organometallic compound.

[0039] D. Solid electrolyte The solid electrolyte covers the dielectric and an optional precoat. The total thickness of the solid electrolyte is typically about 1 to about 50 μm, and in some embodiments, about 5 to about 20 μm. The solid electrolyte typically comprises one or more layers of conductive polymers (e.g., polypyrrole, polyheterocyclic polythiophene, polyaniline, polyacetylene, poly-p-phenylene, polyphenolate, etc.). Thiophene polymers are particularly suitable for use in solid electrolytes. In certain embodiments, for example, a thiophene polymer having repeating units of the following formula (I) can be used.

[0040] [ka]

[0041] In the formula, R7 is linear or branched C1-C 18Alkyl radicals (e.g., methyl, ethyl, n- or isopropyl, n-, iso-, sec- or tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, etc.); C5~C 12 Cycloalkyl radicals (e.g., cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, etc.); C6~C 14 Aryl radicals (e.g., phenyl, naphthyl); C7~C 18 The radical is an aralkyl radical (e.g., benzyl, o-, m-, p-tolyl, 2,3-, 2,4-, 2,5-, 2-6, 3-4-, 3,5-xylyl, mesityl, etc.), where q is an integer from 0 to 8, in some embodiments from 0 to 2, and in one embodiment 0.

[0042] In particular, preferred thiophene polymers are those in which "D" is optionally substituted C2-C3 alkylene radicals. For example, the polymer may include optionally substituted poly(3,4-ethylenedioxythiophene) or derivatives thereof having repeating units of the following general formula (II).

[0043] [ka]

[0044] In a particular embodiment, "q" is 0. A suitable commercially available example of 3,4-ethylenedioxythiophene is available from Heraeus under the name Clevios® M. Other suitable monomers are also described in U.S. Patent No. 5,111,327 to Blohm et al. and U.S. Patent No. 6,635,729 to Groenendaal et al. For example, derivatives of these monomers, which are dimers or trimers of the above monomers, may also be used. Higher molecular derivatives, i.e., tetramers, pentamers, etc., of the monomers, are preferred for use in the present invention. The derivatives may consist of the same or different monomer units, may be used in pure aqueous form, or may be used in mixtures with each other and / or with the monomers. Oxidized or reduced forms of these precursors may also be used.

[0045] To form a polymer, the precursor monomer may be polymerized in the presence of an oxidation catalyst (e.g., chemical polymerization). The oxidation catalyst typically contains transition metal cations such as iron(III), copper(II), chromium(VI), cerium(IV), manganese(IV), manganese(VII), or ruthenium(III) cations. Dopants can also be used to impart an excess charge to the conductive polymer and stabilize its conductivity. Dopants typically contain inorganic or organic anions, such as sulfonic acid ions (e.g., p-toluenesulfonate ions). In certain embodiments, the oxidation catalyst has both catalytic and doping functions, in that it contains both cations (e.g., transition metals) and anions (e.g., sulfonic acids). For example, the oxidation catalyst can be an iron(III) cation-containing transition metal salt, such as an iron(III) halide (e.g., FeCl3) or an iron(III) salt of another inorganic acid (e.g., Fe(ClO4)3 or Fe2(SO4)3), as well as an organic acid, and an iron(III) salt of an inorganic acid containing an organic radical. Examples of iron(III) salts of inorganic acids containing organic radicals include, for example, C1-C 20 This includes iron(III) salts of monosulfate alkanols (e.g., iron(III) salts of lauryl sulfate). Similarly, examples of iron(III) salts of organic acids include, for example, C1-C20 Iron(III) salts of alkanesulfonic acids (e.g., methane, ethane, propane, butane, or dodecanesulfonic acid); iron(III) salts of aliphatic perfluorosulfonic acids (e.g., trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, or perfluorooctanesulfonic acid); aliphatic C1-C 20 Iron(III) salts of carboxylic acids (e.g., 2-ethylhexylcarboxylic acid); iron(III) salts of aliphatic perfluorocarboxylic acids (e.g., trifluoroacetic acid or perfluorooctanoic acid); C1-C 20 These include iron(III) salts of aromatic sulfonic acids (e.g., benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid) optionally substituted with alkyl groups; and iron(III) salts of cycloalkanesulfonic acids (e.g., camphor sulfonic acid). Mixtures of these iron(III) salts may also be used. Iron(III)-p-toluenesulfonates, iron(III)-o-toluenesulfonates, and mixtures thereof are particularly preferred. One preferred example of a commercially available iron(III)-p-toluenesulfonate is available from Heraeus under the name Clevios® C.

[0046] The oxidation catalyst and precursor monomer may be applied sequentially or together to initiate the polymerization reaction. For example, the monomer may be mixed with the oxidation catalyst first to form a precursor solution. In certain embodiments, less than the stoichiometric amount of oxidation catalyst typically required may be used to help slow down the polymerization of the monomer, producing shorter oligomers than would be possible if the monomer were fully polymerized, and allowing for good penetration into high specific charge powders. For example, if the monomer contains a thiophene monomer (e.g., 3,4-ethylenedioxythiophene), the molar ratio typically required for polymerization of the monomer is about 1 mole of monomer to 18 moles of oxidation catalyst. However, less than 18 moles of oxidation polymerization catalyst per mole of monomer (e.g., 3,4-ethylenedioxythiophene), e.g., about 15 moles or less, about 4 to about 12 moles in some embodiments, and about 5 to about 10 moles in some embodiments may be present in the polymerization solution.

[0047] The polymerization solution may also contain other components, such as one or more solvents, in addition to monomers, oxidation catalysts, and optionally selected dopants. In particular, preferred solvents may include, for example, water, alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, and butanol); glycols (e.g., propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, polyethylene glycol, ethoxydiglycol, and dipropylene glycol); glycol ethers (e.g., methyl glycol ether, ethyl glycol ether, and isopropyl glycol ether); ethers (e.g., diethyl ether and tetrahydrofuran); triglycerides; ketones; esters (e.g., ethyl acetate, butyl acetate, diethylene glycol ether acetate, and methoxypropyl acetate); amides (e.g., dimethylformamide, dimethylacetamide, dimethylcapryl / caprin fatty acid amide, and N-alkylpyrrolidone); nitriles (e.g., acetonitrile, propionitrile, butyronitrile, and benzonitrile); sulfoxides or sulfones (e.g., dimethyl sulfoxide (DMSO) and sulfolane), and mixtures of any of the above (e.g., water and alcohol).

[0048] The polymerization solution is typically maintained at a relatively low temperature during the reaction, such as approximately -20°C to approximately 50°C, approximately -15°C to approximately 30°C in some embodiments, and approximately -10°C to approximately 10°C in some embodiments. The solution can be applied to the anode body using any suitable coating technique known in the art, such as screen printing, dipping, electrophoretic coating, and spraying. Regardless of the coating technique used, the monomers present in the anode body generally initiate the reaction once to form a polymer layer. The period during which the monomers can react on the anode body is usually long enough to allow the polymer to properly impregnate the small pores of the high specific charge powder. In most embodiments, for example, this period ("impregnation time") is approximately 1 minute or more, approximately 1.5 minutes or more in some embodiments, and approximately 2 to approximately 5 minutes in some embodiments. After the reaction, the resulting conductive polymer layer can be brought into contact with a washing solution to remove various by-products, excess catalyst, etc. The period during which the cleaning solution is in contact with the conductive polymer layer ("cleaning time") is typically long enough to ensure that by-products, excess catalyst, etc., are thoroughly removed from the small pores of the high specific charge powder. The cleaning period can be, for example, about 25 minutes or more, about 30 minutes or more in some embodiments, and about 45 to 90 minutes in some embodiments. During this period, cleaning may be carried out in a single step or in multiple steps, in which case the total time of each step is within the above range. The cleaning solution may vary as desired, but is typically one or more solvents (e.g., water, alcohol, etc.) and optionally dopants such as those described above.

[0049] Once cleaned, the conductive polymer layer may be dried at a temperature typically above 15°C, above 20°C in some embodiments, and between 20°C and 80°C in some embodiments. This polymer layer may also be repaired after formation. Repair may be performed after each application of the conductive polymer layer, or after the entire conductive polymer coating has been applied. In some embodiments, the conductive polymer may be repaired by immersing the anode body in an electrolyte solution, and then applying a constant voltage to the solution until the current drops to a pre-selected level. If desired, such repair may be carried out in multiple steps. For example, the electrolyte solution may be a diluted solution of monomers, catalysts, and dopants in an alcohol solvent (e.g., ethanol).

[0050] In the process described above, the conductive polymer is generally formed "in situ" on the anode body. Of course, this is not always necessary. In other embodiments, for example, the conductive polymer may be prepolymerized. In one embodiment, for example, a prepolymerized polymer is an intrinsically conductive polymer having a positive charge located on the main chain, which is at least partially offset by anions covalently bonded to the polymer. Such polymers can have relatively high specific conductivity in a dry state of about 1 siemens per centimeter ("S / cm") or more, about 10 S / cm or more in some embodiments, about 25 S / cm or more in some embodiments, about 40 S / cm or more in some embodiments, and about 50 to about 500 S / cm in some embodiments. An example of a suitable intrinsically conductive thiophene polymer may have repeating units of the following formula (III).

[0051] [ka]

[0052] In the formula, R is (CH2) a -O-(CH2) b -L is a bond or HC([CH2] cH) is such that a is 0 to 10, in some embodiments 0 to 6, and in some embodiments 1 to 4 (e.g., 1), b is 1 to 18, in some embodiments 1 to 10, and in some embodiments 2 to 6 (e.g., 2, 3, 4, or 5), c is 0 to 10, in some embodiments 0 to 6, and in some embodiments 1 to 4 (e.g., 1), and Z is SO3 - , C(O)O - BF4 - CF3SO3 - SbF6 - , N(SO2CF3)2 - C4H3O4 - ClO4 - X is an anion such as hydrogen, an alkali metal (e.g., lithium, sodium, rubidium, cesium, or potassium), or an cation such as ammonium.

[0053] In one particular embodiment, Z in formula (III) is a sulfonate ion, and thus the originally conductive polymer contains repeating units of the following formula (IV).

[0054] [ka]

[0055] In the formulas, R and X are as defined above. In formula (III) or (IV), a is preferably 1 and b is preferably 3 or 4. Similarly, X is preferably sodium or potassium.

[0056] If desired, the polymer can be a copolymer containing other types of repeating units. In such embodiments, the repeating units of formula (III) typically constitute about 50 mol.% or more of the total amount of repeating units in the copolymer, about 75 mol.% to about 99 mol.% in some embodiments, and about 85 mol.% to about 95 mol.% in some embodiments. Naturally, the polymer may also be a homopolymer containing up to 100 mol.% of the repeating units of formula (III). Specific examples of such homopolymers include poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butanesulfonic acid, salt) and poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-propanesulfonic acid, salt).

[0057] In another embodiment, the inherently conductive polymer has repeating thiophene units of the following general formula (V).

[0058] [ka]

[0059] In the formula, a and b are as defined above, R5 is a optionally substituted C1-C6 linear or branched alkyl group (e.g., methyl) or halogen atom (e.g., fluorine), and X is a hydrogen atom, alkali metal (e.g., Li, Na, or K), NH(R 1 )3 or HNC5H5(R 1 Each of these is independently a hydrogen atom or, optionally, a substituted C1-C6 alkyl group.

[0060] Specific examples of thiophene compounds used to form such repeats are described in U.S. Patent No. 9,718,905, for example, 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1 -Propyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno [3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopropyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isobutyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopentyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-flu Sodium oro-1-propanesulfonate, potassium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, potassium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid, ammonium 3-[(2,3-dihydrothieno[3,4-b]-[1,This may include triethylammonium dioxin-2-yl)methoxy-1-methyl-1-propanesulfonate, and combinations thereof, and derivatives thereof. Each of the exemplified thiophene monomers above can be prepared from thieno[3,4-b]-1,4-dioxin-2-methanol and branched sultone compounds in accordance with known methods (e.g., Journal of Electroanalytical Chemistry, Vol. 443, pp. 217-226 (1998)).

[0061] "External" conductive polymers may also be used, which generally require the presence of separate counterions not covalently bonded to the polymer. An example of such an external conductive polymer is poly(3,4-ethylenedioxythiophene). The counterions may be anionic monomers or anionic polymers that counteract the charge of the conductive polymer. Anionic polymers can be, for example, polymeric carboxylic acids (e.g., poly(meth)acrylic acids such as poly-2-sulfoethyl(meth)acrylate or poly-3-propylsulfo(meth)acrylate; polymaleic acid, etc.); polymeric sulfonic acids (e.g., polystyrene sulfonic acid ("PSS"), polyvinyl sulfonic acid, etc.), as well as anions derived from their salts such as alkali metal salts, alkaline earth metal salts, transition metal salts, or ammonium salts. Similarly, suitable anionic monomers are C1-C 20 Alkanesulfonic acids (e.g., dodecanesulfonic acid); aliphatic fluorosulfonic acids (e.g., trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, perfluorooctanesulfonic acid, trifluoromethanesulfonimide, etc.); aliphatic C1-C 20 Carboxylic acids (e.g., 2-ethylhexylcarboxylic acid); aliphatic fluorocarboxylic acids (e.g., trifluoroacetic acid or perfluorooctanoic acid); C1-C 20Aromatic sulfonic acids optionally substituted with alkyl groups (e.g., benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid); cycloalkanesulfonic acids (e.g., camphor sulfonic acid); boron compounds (e.g., tetrafluoroboric acid); phosphate compounds (e.g., hexafluorophosphate); and others, as well as derivatives of their salts, such as alkali metal salts, alkaline earth metal salts, transition metal salts, or ammonium salts. Particularly preferred counteranions are anionic polymers, such as those derived from polymeric carboxylic acids or sulfonic acids (e.g., polystyrenesulfonic acid ("PSS")). The molecular weight of such compounds is typically in the range of about 1,000 to about 2,000,000, and in some embodiments, about 2,000 to about 500,000.

[0062] Whether intrinsically or externally conductive, the prepolymerized polymer layer may be applied to the anode body in various forms, such as solutions or dispersions. Intrinsically conductive polymers are preferably applied in the form of solutions, for example, while externally conductive polymers are preferably applied in the form of dispersions.

[0063] When a solution is used, the concentration of the polymer can vary depending on the desired viscosity of the layer to be applied to the anode and the particular method thereof. However, typically the polymer constitutes about 0.1 to about 10% by weight of the solution, about 0.4 to about 5% by weight in some embodiments, and about 0.5 to about 4% by weight in some embodiments. The solvent can similarly constitute about 90% to about 99.9% by weight of the solution, about 95% to about 99.6% by weight in some embodiments, and about 96% to about 99.5% by weight in some embodiments. While other solvents may certainly be used, water is generally preferred as the primary solvent such that the solution is made an "aqueous" solution. In most embodiments, for example, water constitutes at least about 50% by weight of the solvent used, at least about 75% by weight in some embodiments, and about 90% to 100% by weight in some embodiments. The solution may, if used, be applied to the anode using any known technique such as immersion, casting (e.g., curtain coating, spin coating, etc.), or printing (e.g., gravure printing, offset printing, screen printing, etc.). The resulting conductive polymer layer may be dried and / or washed after being applied to the anode.

[0064] When a dispersion is used, the conductive polymer is generally in the form of pre-polymerized conductive particles. Such particles typically have an average size (e.g., diameter) of about 1 to about 100 nanometers, about 2 to about 80 nanometers in some embodiments, and about 4 to about 50 nanometers in some embodiments. The particle diameter can be determined using known techniques such as ultracentrifugation and laser diffraction. The shape of the particles can also vary. In a particular embodiment, for example, the particles are spherical. However, it should be understood that other shapes such as plate-like, rod-like, disc-like, rod-like, tubular, and irregular shapes are also intended by the present invention. The concentration of particles in the dispersion can vary depending on the desired viscosity of the dispersion and the particular method by which the dispersion is applied to the capacitor element. However, typically the particles constitute about 0.1 to about 10% by weight of the dispersion, about 0.4 to about 5% by weight in some embodiments, and about 0.5 to about 4% by weight in some embodiments.

[0065] The dispersion may also contain one or more binders to further enhance the tackiness of the polymer layer and improve the safety of particles in the dispersion. The binders may be organic in nature, such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyacrylic acid esters, polyacrylamide, polymethacrylate, polymethacrylate, polyacrylonitrile, styrene / acrylic acid esters, vinyl acetate / acrylic acid esters and ethylene / vinyl acetate copolymers, polybutadiene, polyisoprene, polystyrene, polyether, polyester, polycarbonate, polyurethane, polyamide, polyimide, polysulfone, melamine formaldehyde resin, epoxide resin, silicone resin, or cellulose. Crosslinking agents may also be used to enhance the tackiness of the binder. Such crosslinking agents may include, for example, melamine compounds, masked isocyanates or functional silanes (such as 3-glycidoxypropyltrialkoxysilane, tetraethoxysilane, and tetraethoxysilane hydrolysates), or crosslinkable polymers (such as polyurethanes, polyacrylates, or polyolefins), and subsequent crosslinking.

[0066] Dispersants may also be used to enhance the ability to coat layers onto the anode. Suitable dispersants include aliphatic alcohols (e.g., methanol, ethanol, i-propanol, and butanol), aliphatic ketones (e.g., acetone and methyl ethyl ketone), aliphatic carboxylic acid esters (e.g., ethyl acetate and butyl acetate), aromatic hydrocarbons (e.g., toluene and xylene), aliphatic hydrocarbons (e.g., hexane, heptane, and cyclohexane), chlorolated hydrocarbons (e.g., dichloromethane and dichloroethane), aliphatic nitriles (e.g., acetonitrile), aliphatic sulfoxides and sulfones (e.g., dimethyl sulfoxide and sulfolane), aliphatic carboxylic acid amides (e.g., methylacetamide, dimethylacetamide, and dimethylformamide), aliphatic and araliphatic ethers (e.g., diethyl ether and anisole), water, and mixtures of any of the solvents mentioned above. Water is a particularly suitable dispersant.

[0067] In addition to the above, other components may still be used in the dispersion. For example, conventional fillers having a size of about 10 nanometers to about 100 micrometers, in some embodiments about 50 nanometers to about 50 micrometers, and in some embodiments about 100 nanometers to about 30 micrometers may be used. Examples of such fillers include calcium carbonate, silicate, silica, calcium sulfate or barium sulfate, aluminum hydroxide, glass fibers or bulbs, wood flour, cellulose powder, carbon black, conductive polymers, and the like. The fillers may be introduced into the dispersion in powder form, but may also be present in other forms such as fibers.

[0068] Surface active substances, such as ionic or nonionic surfactants, may also be used in the dispersion. Furthermore, adhesives such as organic functional silanes or their hydrolysates, e.g., 3-glycidoxypropyltrialkoxysilane, 3-aminopropyl-triethoxysilane, 3-mercaptopropyl-trimethoxysilane, 3-methacrylateoxypropyltrimethoxysilane, vinyltrimethoxysilane, or octyltriethoxysilane may also be used. The dispersion may also contain ether group-containing compounds (e.g., tetrahydrofuran), lactone group-containing compounds (e.g., γ-butyrolactone or γ-valerolactone), amide or lactam group-containing compounds (e.g., caprolactam, N-methylcaprolactam, N,N-dimethylacetamide, N-methylacetamide, N,N-dimethylformamide (DMF), N-methylformamide, N-methylformanilide, N-methylpyrrolidone (NMP), N-octylpyrrolidone, or pyrrolidone), sulfones, and sulfones. The product may contain additives that improve conductivity, such as sulfoxides (e.g., sulfolane (tetramethylene sulfone) or dimethyl sulfoxide (DMSO)), sugars or sugar derivatives (e.g., saccharose, glucose, fructose, or lactose), sugar alcohols (e.g., sorbitol or mannitol), furan derivatives (e.g., 2-furanic acid or 3-furanic acid), and alcohols (e.g., ethylene glycol, glycerol, diethylene glycol, or triethylene glycol).

[0069] The dispersion can be applied using various known techniques such as spin coating, impregnation, injection, drop coating, injection, spraying, doctor bladeding, brush coating, printing (e.g., inkjet, screening, or pad printing), or immersion. The viscosity of the dispersion is typically about 0.1 to about 100,000 mPas (100s). -1 (Measured by shear rate), in some embodiments it is about 1 to about 10,000 mPas, in some embodiments it is about 10 to about 1,500 mPas, and in some embodiments it is about 100 to about 1,000 mPas.

[0070] Solid electrolytes may be formed from multiple layers, such as inner and / or outer layers. In this context, the term “inner” refers to one or more layers covering the dielectric, whether directly or via another layer (e.g., a pre-coat layer). Inner layers typically contain, for example, in-situ polymers and / or polymers that are intrinsically conductive, such as those described above. One or more inner layers may be used. For example, a solid electrolyte typically contains 2 to 30 inner layers, 4 to 20 in some embodiments, and about 5 to 15 in some embodiments (e.g., 10 layers). A solid electrolyte contains only “inner layers,” and therefore the solid electrolyte is substantially formed from the same material, i.e., from polymers that are intrinsically conductive and / or in-situ polymer layers. Nevertheless, in other embodiments, the solid electrolyte may also contain one or more optional “outer” conductive polymer layers that are formed from a different material than the inner layers and cover the inner layers. For example, the outer layer may be formed from a dispersion of an externally conductive polymer. In a particular embodiment, the outer layer is primarily formed from such an external conductive polymer, constituting about 50% by weight or more of the individual outer layers, about 70% by weight or more in some embodiments, and about 90% by weight or more (e.g., 100% by weight) in some embodiments. One or more outer layers may be used. For example, the solid electrolyte may include 2 to 30, 4 to 20 in some embodiments, and about 5 to 15 outer layers.

[0071] E. External polymer coating An external polymer coating covering the solid electrolyte may also be used, if applicable. If used, the external polymer coating typically comprises one or more layers formed from pre-polymerized conductive polymer particles such as those described above (e.g., a dispersion of external conductive polymer particles). The external coating can further penetrate the edge regions of the capacitor body to increase adhesion to the dielectric, resulting in a more mechanically robust portion, which can reduce equivalent series resistance and leakage current. Since the external coating is generally intended to improve edge coverage rather than impregnate the interior of the anode body, the particles used in the external coating can be larger in size than those used in the outer layer of the solid electrolyte. For example, the ratio of the average particle size of the particles used in the external polymer coating to the average particle size of the particles used in any dispersion of the solid electrolyte is typically about 1.5 to about 30, about 2 to about 20 in some embodiments, and about 5 to about 15 in some embodiments. For example, the particles used in the dispersion of the external coating may have an average size of about 80 to about 500 nanometers, in some embodiments about 90 to about 250 nanometers, and in some embodiments about 100 to about 200 nanometers.

[0072] If desired, a crosslinking agent may also be used in the external polymer coating to enhance adhesion to the solid electrolyte. Typically, the crosslinking agent is applied before the application of the dispersion used for the external coating. Suitable crosslinking agents are described, for example, in U.S. Patent Publication 2007 / 0064376 to Merker et al., and include, for example, amines (e.g., diamines, triamines, oligomeric amines, polyamines, etc.); polyvalent metal cations such as salts or compounds of Mg, Al, Ca, Fe, Cr, Mn, Ba, Ti, Co, Ni, Cu, Ru, Ce, or Zn; phosphonium compounds; sulfonium compounds, etc. In particular, preferred examples include, for example, 1,4-diaminocyclohexane, 1,4-bis(amino-methyl)cyclohexane, ethylenediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine, N,N-dimethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,4-butanediamine, and mixtures thereof.

[0073] The crosslinking agent is typically applied from a solution or dispersion, and its pH, determined at 25°C, is 1 to 10, 2 to 7 in some embodiments, and 3 to 6 in others. Acidic compounds can be used to help achieve the desired pH level. Examples of solvents or dispersants for the crosslinking agent include water, or organic solvents such as alcohols, ketones, or carboxylic acid esters. The crosslinking agent may be applied to the capacitor body by any known process, such as spin coating, impregnation, casting, drop coating, spray coating, vapor deposition, sputtering, sublimation, knife coating, painting, or printing, e.g., inkjet printing, screen printing, or pad printing. Once applied, the crosslinking agent may be dried before the polymer dispersion is applied. This process may then be repeated until the desired thickness is reached. For example, the total thickness of the entire external polymer coating, including the layers of crosslinking agent and dispersion, can range from about 1 to about 50 μm, about 2 to about 40 μm in some embodiments, and about 5 to about 20 μm in others.

[0074] F. Moisture barrier layer If desired, a moisture barrier layer covering a solid electrolyte and / or an optional external polymer coating may be used. The moisture barrier layer can be formed from a variety of different materials, such as hydrophobic elastomers, e.g., silicones, fluoropolymers. Silicone polymers are particularly suitable for use as the moisture barrier layer of the present invention. Such elastomers are typically derived from the following general formula polyorganosiloxanes.

[0075] [ka]

[0076] In the formula, x is an integer greater than 1, and R1, R2, R3, R4, R5, R6, R7, and R8 are independently monovalent groups typically containing 1 to about 20 carbon atoms, such as alkyl groups (e.g., methyl, ethyl, propyl, pentyl, octyl, undecyl, octadecyl, etc.); alkoxy groups (e.g., methoxy, ethoxy, propoxy, etc.); carboxyalkyl groups (e.g., acetyl); cycloalkyl groups (e.g., cyclohexyl); alkenyl groups (e.g., vinyl, allyl, butenyl, hexenyl, etc.); aryl groups (e.g., phenyl, tolyl, xylyl, benzyl, 2-phenylethyl, etc.); and halogenated hydrocarbon groups (e.g., 3,3,3-trifluoropropyl, 3-chloropropyl, dichlorophenyl, etc.). Examples of such polyorganosiloxanes include, for example, polydimethylsiloxane ("PDMS": polydimethylsiloxane), polymethylhydrogensiloxane, dimethyldiphenylpolysiloxane, dimethyl / methylphenylpolysiloxane, polymethylphenylsiloxane, methylphenyl / dimethylsiloxane, vinyldimethyl-terminated polydimethylsiloxane, vinylmethyl / dimethylpolysiloxane, vinyldimethyl-terminated vinylmethyl / dimethylpolysiloxane, divinylmethyl-terminated polydimethylsiloxane, vinylphenylmethyl-terminated polydimethylsiloxane, dimethylhydro-terminated polydimethylsiloxane, methylhydro / dimethylpolysiloxane, methylhydro-terminated methyloctylpolysiloxane, methylhydro / phenylmethylpolysiloxane, and fluoromodified polysiloxanes. To form elastomers, polyorganosiloxanes can be crosslinked using any of the various known techniques, such as catalytic curing (e.g., platinum catalyst), vulcanization at room temperature, and water curing. A crosslinking agent such as an alkoxysilane having the formula Si-OR may be used, where R is H, alkyl (e.g., methyl), alkenyl, or carboxyalkyl (e.g., acetyl).

[0077] The material used to form the moisture barrier layer is generally desirable to be hydrophobic, have a relatively low modulus, and possess some degree of flexibility, which can help absorb some of the thermal stress caused by the expansion of the casing and may also be able to withstand compressive forces. The flexibility of the material can be characterized by a correspondingly low modulus of elasticity ("Young's modulus"), such as about 5,000 kilopascals ("kPa") or less, about 1 to about 2,000 kPa in some embodiments, and about 2 to about 500 kPa in some embodiments, when measured at a temperature of about 25°C. The material also usually possesses some strength, which allows it to maintain its shape even when subjected to compressive forces. For example, the material can have a tensile strength of about 1 to about 5,000 kPa, about 10 to about 2,000 kPa in some embodiments, and about 50 to about 1,000 kPa when measured at a temperature of about 25°C. Under the above conditions, hydrophobic elastomers can further enhance the ability of capacitors to function under harsh conditions.

[0078] Nonconductive fillers may be used in the moisture barrier layer to help achieve desired flexibility and strength properties. When used, such additives typically constitute about 0.5% to about 30% by weight of the moisture barrier layer, about 1% to about 25% by weight in some embodiments, and about 2% to about 20% by weight in some embodiments. Silicone elastomers can constitute about 70% to about 99.5% by weight of the moisture barrier layer, about 75% to about 99% by weight in some embodiments, and about 80% to about 98% by weight in some embodiments. A specific example of such fillers is silica. Most forms of silica have a relatively hydrophilic surface due to the presence of silanol groups (Si-OH), but silica also has a surface that is (CH3) nThe surface may optionally be treated to include a -Si- group (where n is an integer from 1 to 3), thereby further enhancing the hydrophobicity of the moisture barrier layer. The surface treatment agent can be, for example, an organosilicon compound monomer having a hydrolyzable group or a partial hydrolysate thereof. Examples of such compounds include organosilazanes, which are silane coupling agents like those mentioned above.

[0079] The moisture barrier layer may be applied to any surface of the capacitor to achieve the desired characteristics. For example, the moisture barrier layer may be located on the top, bottom, and / or side surfaces of the capacitor. Similarly, the moisture barrier layer may be located on the front and / or rear surfaces of the capacitor. The moisture barrier layer may cover all or only a portion of the surface to which it is applied. In one embodiment, for example, the moisture barrier layer covers about 30% or more, in some embodiments about 40% or more, and in some embodiments about 50% or more of the surface of the capacitor to which it is applied.

[0080] G. Other optional components If desired, the capacitor element may also contain other layers, as known in the art. For example, an adhesive layer may optionally be formed between the dielectric and the solid electrolyte. The adhesive layer may be present, for example, between the dielectric and the precoat layer and / or between the precoat layer and the solid electrolyte. Regardless, the adhesive layer is usually formed from a relatively insulating resin material (natural or synthetic). Such materials have an impedance of more than about 10 Ω·cm, more than about 100 in some embodiments, more than about 1,000 Ω·cm in some embodiments, and more than about 1 x 10 in some embodiments. 5 Greater than Ω·cm, and in some embodiments, about 1 x 10⁻¹⁰ 10It can have a resistivity greater than Ω·cm. Some resin materials that can be used in the present invention include, but are not limited to, polyurethane, polystyrene, and esters of unsaturated or saturated fatty acids (e.g., glycerides). For example, suitable fatty acid esters include, but are not limited to, esters of lauric acid, myristic acid, palmitic acid, stearic acid, eleostearic acid, oleic acid, linoleic acid, linolenic acid, aloylitic acid, and sheroic acid. These fatty acid esters have been found to be particularly useful for forming "drying oils" when used in relatively complex combinations, thereby enabling the resulting film to rapidly polymerize into a stable layer. Such drying oils may include monoglycerides, diglycerides and / or triglycerides, which have a glycerol backbone with one, two, and three fatty acyl residues to be esterified, respectively. For example, some suitable drying oils that can be used include, but are not limited to, olive oil, linseed oil, castor oil, tuna oil, soybean oil, and shellac. These and other adhesive materials are described in more detail in U.S. Patent No. 6,674,635 to Fife et al.

[0081] If desired, these portions may be coated with a carbon layer (e.g., graphite) and a silver layer, respectively. The silver coating can act, for example, as a solderable conductor, a contact layer, and / or a charge collector for a capacitor, while the carbon coating can restrict the silver coating from contacting the solid electrolyte. Such coatings may cover part or all of the solid electrolyte. Various techniques such as dipping, brushing, spraying, and printing may be used to apply such layers.

[0082] II. Terminals Once formed, the capacitor element may be provided with terminals. As specified above, the capacitor generally includes at least two separate, spaced-apart anode terminals to which the individual exposed anode leads are electrically connected. The capacitor also includes a cathode terminal to which the solid electrolyte of the capacitor element is electrically connected.

[0083] Any conductive material may be used to form the terminals, such as conductive metals (e.g., copper, nickel, silver, nickel, zinc, tin, palladium, lead, copper, aluminum, molybdenum, titanium, iron, zirconium, magnesium, and their alloys). Particularly preferred conductive metals include, for example, copper, copper alloys (e.g., copper-zirconium, copper-magnesium, copper-zinc, or copper-iron), nickel, and nickel alloys (e.g., nickel-iron). The thickness of the terminals is generally selected to minimize the thickness of the capacitor. For example, the thickness of the terminals can range from about 0.05 to about 1 millimeter, in some embodiments from about 0.05 to about 0.5 millimeters, and from about 0.07 to about 0.2 millimeters. One exemplary conductive material is a copper-iron alloy metal sheet available from Wieland (Germany). If desired, the surface of the terminals may be electroplated with nickel, silver, gold, tin, etc., as known in the art, so that the final part can be securely mounted to the circuit board. In one particular embodiment, both surfaces of the terminal are plated with nickel and silver flash, respectively, while the mounting surface is also plated with a tin solder layer. The terminal can be connected to the capacitor element using any technique known in the art, such as resistance welding, laser welding, or conductive adhesive.

[0084] Referring to Figures 2-3, a particular embodiment of a capacitor 200 is shown, which includes a cathode terminal 206 electrically connected to a solid electrolyte (not shown) of a capacitor element 208. The capacitor element 208 may include opposing first and second ends 205 and 207, as well as opposing lower and upper surfaces 210 and 207. The cathode terminal 206 is generally planar in the sense that it is formed, if not entirely, primarily from components extending on the same or substantially the same plane. The cathode terminal 206 is positioned adjacent to the lower surface 210 of the capacitor element 208 and is generally parallel to this surface. In such a particular embodiment, a conductive adhesive 212 connects the cathode terminal 206 to the capacitor element 208. The conductive adhesive 212 may include, for example, conductive metal particles contained in a resin composition. The metal particles may be silver, copper, gold, platinum, nickel, zinc, bismuth, and the like. The resin composition may include a thermosetting resin (e.g., epoxy resin), a curing agent (e.g., acid anhydride), and a coupling agent (e.g., silane coupling agent). A suitable conductive adhesive may be described in U.S. Patent Publication 2006 / 0038304 to Osako et al. The conductive adhesive can be applied to the cathode terminal 206 using any of the following techniques. Printing techniques may be used, for example, for their practical and cost-saving benefits. The conductive adhesive 212 can be cured. For example, a hot press can be used to apply heat and pressure so that the capacitor element 208 is properly bonded to the cathode terminal 206 by the adhesive.

[0085] The capacitor 200 also includes a first exposed anode lead portion 218 extending from a first end 205 of the capacitor element 208, and a second exposed anode lead portion 220 extending from a second opposing end 207 of the capacitor element 208. The exposed anode lead portion 218 is electrically connected to the first anode terminal 201, and the exposed anode lead portion 220 is electrically connected to the second anode terminal 203. The first anode terminal 201 may also include a planar portion 202 that is substantially parallel to the lower surface 210 of the capacitor element 208 and / or the cathode terminal 206. The first anode terminal 201 may also include an upright portion 214 that connects the planar portion 202 to the exposed first anode lead portion 218. Similarly, the second anode terminal 203 may include a planar portion 204 that is substantially parallel to the lower surface 210 of the capacitor element 208 and / or the cathode terminal 206. The second anode terminal 203 may also include an upright portion 216 that connects the planar portion 204 to the exposed second anode lead portion 220. As specified, the planar portions 202, 204 of the individual anode terminals are planar and generally parallel to the lower surface 210 of the capacitor element 208, and can therefore be located below the individual exposed anode lead portions 218, 220. However, in one embodiment, the first upright portion 214 and the second upright portion 216 may be thicker or extended portions of the first planar portion 202 and / or the second planar portion 204 of the individual anode terminals 201, 203. For example, in one embodiment, the first and / or second anode terminals 201, 203 have a height selected based on the distance "d" from the bottom surfaces 222, 224 of the exposed anode lead portions 218, 220 to the lower surface 210 of the capacitor element, in which case the distance "d" is typically in the range of about 0.1 to about 1 millimeter, in some embodiments about 0.2 to about 0.8 millimeters, and in some embodiments about 0.3 to about 0.6 millimeters. Naturally, the planar portions 202, 204 may also have a height equal to the distance "d", thus the upright portions are not required.Although not shown in Figures 2 and 3, the upright portions 214 and 216 have a "U-shape" which can further increase surface contact and mechanical stability of the exposed anode lead portions 218 and 220.

[0086] The first exposed anode lead portion 218 and the second exposed anode lead portion 220 may be electrically connected to the individual anode terminals 201, 203 using any technique known in the art, such as resistance welding, laser welding, or conductive adhesive (either directly to the planar portions 202, 204 or via the upright portions 214, 216, as discussed above). The laser generally includes a resonator containing a laser medium capable of stimulated emission and photons by an energy source that excites elements in the laser medium. One preferred type of laser is one in which the laser medium consists of neodymium (Nd)-doped aluminum and yttrium garnet (YAG). The excited particles are neodymium ions Nd 3+ The energy source can supply continuous energy to a continuous laser beam emitting a pulsed laser beam or a laser medium emitting an energy discharge. The same or different techniques may be used for each exposed anode lead.

[0087] In some cases, the capacitor element 208 can have a relatively small thickness or height "h" in the range of about 0.4 to about 1.5 millimeters, in some embodiments about 0.5 to about 1.2 millimeters, and in some embodiments about 0.6 to about 1 millimeter. In particular, in one embodiment, such a small height "h" can further reduce the distance "d" to improve the stability of the capacitor and further contribute to an even lower ESL of the capacitor. For example, in one embodiment, the distance "d" can have a value based on the height "h". In such embodiments, the length of the leads and terminals can be shortened by having a distance where the height "h" is about 0.1 times the height "h", such as about 0.2 times the height "h", about 0.3 times, about 0.4 times, about 0.5 times, etc. The capacitor element 208 can also have a high aspect ratio (ratio of the width "w" to the height "h" of the capacitor element) for at least part reasons of the small thickness discussed above. Such high aspect ratios can be approximately 2 or higher, such as approximately 3 or higher, approximately 4 or higher, approximately 5 or higher, approximately 6 or higher, etc. In particular, as discussed above, the inventors have found that capacitors having such shapes and arrangements can further contribute to the formation of capacitors with low ESL characteristics and small, low profile.

[0088] III. Cabinet The capacitor element is largely enclosed within the housing, so that at least a portion of the planar portion of the first anode terminal, the planar portion of the second anode terminal, and the cathode terminal are exposed for mounting on a circuit board. Referring again to Figures 2-3, for example, the capacitor element 208 may be enclosed within the housing 226, so that at least the lower surface of the planar portion 202 of the anode terminal 201, the planar portion 204 of the anode terminal 203, and / or the planar cathode terminal 206 are exposed. In some cases, only these surfaces are exposed. The housing is usually formed from a thermosetting resin. Examples of such resins include, for example, epoxy resins, polyimide resins, melamine resins, urea-formaldehyde resins, polyurethane resins, phenolic resins, and polyester resins. Epoxy resins are also particularly preferred. Further additives such as photoinitiators, viscosity modifiers, suspension aids, pigments, stress reducers, nonconductive fillers, and stabilizers may also be used. For example, non-conductive fillers may include inorganic oxide particles and composites (e.g., alumina-coated silica particles) such as silica, alumina, zirconia, magnesium oxide, iron oxide, copper oxide, zeolite, silicate, and clay (e.g., smectite clay), as well as mixtures thereof.

[0089] The present invention can be better understood by referring to the following embodiments.

[0090] Test Procedure S-parameters S 21 The parameters were measured over various frequencies using a vector network analyzer. The parameters were also modeled using the equivalent circuit shown in Figure 4. Impedance Impedance was measured over various frequencies using a vector network analyzer.

[0091] Equivalent series resistance (ESR) The equivalent series resistance can be measured using an HP4284A LCR meter with Kelvin leads, under a 0-volt DC bias and a 10 mVAC signal. The operating frequency was 100 kHz, and the temperature was 23°C + 2°C. ESR can be measured from one or more of the cathode and anode terminals. When using multiple anode terminals, the average ESR may be reported.

[0092] Dielectric Loss Tangent The dielectric loss tangent can be measured using an LCZHP4284A LCR meter with a Kelvin lead, under a 0-volt DC bias and a 10 mVAC signal. The operating frequency can be 120 Hz, and the temperature can be 23°C + 2°C.

[0093] capacitance Capacitance was measured using a Keithley 3330 Precision LCZ meter with a Kelvin lead, with a DC bias of 2.2 volts and a peak of 0.5 volts relative to the peak synusoidal signal. The operating frequency was set to 120 Hz, and the temperature could be 23°C + 2°C.

[0094] Leakage current The leakage current can be measured using a leak test meter (YHP4140B) at a temperature of 23°C + 2°C, at a minimum of 5 minutes after setting the rated voltage (e.g., 2.5V) with a 1k ohm resistor to limit the charging current.

[0095] Example 1 Anode samples were formed using tantalum powder with a density of 70,000 μFV / g. Each anode sample was fitted with a tantalum wire and weighed at 6.0 g / cm². 3The material was pressed to a density of 5.08 x 3.52 x 0.52 mm. The resulting pellets had a size of 5.08 x 3.52 x 0.52 mm. These pellets were sintered at 1,275°C, and then a second tantalum wire was welded to the opposite end of the pellet (Figure 1A). During lead welding, the pellets were deoxygenated at 860°C and sintered again at 1300°C. These pellets were anodic-oxidized to 9.3 volts in a water / phosphate electrolyte at 80°C to form a dielectric layer. Next, a conductive polymer coating was formed by immersing the anode in a butanol solution of iron(III) toluenesulfonate (Clevios® C, Heraeus), and consequently in 3,4-ethylenedioxythiophene (Clevios® M, Heraeus), and polymerization. 45 minutes after polymerization, a thin layer of poly(3,4-ethylenedioxythiophene) was formed on the surface of the dielectric. The anode was washed in a 2% aqueous solution of p-toluenesulfonic acid, followed by washing in butanol to remove reaction by-products, then anodic-oxidized in a liquid electrolyte, and washed again in deionized water. This process was repeated six times. After this, the parts were immersed in dispersed poly(3,4-ethylenedioxythiophene) (Clevios® K, Heraeus) with a solid content of 2.0% and a viscosity of 20 mPa.s. During coating, the parts were dried at 125°C for 20 minutes. This process was repeated three times. After this, the parts were immersed in dispersed poly(3,4-ethylenedioxythiophene) (Clevios® K, Heraeus) with a solid content of 2.0% and a viscosity of 160 mPa.s. During coating, the parts were dried at 125°C for 20 minutes. This process was repeated fourteen times. Next, a graphite dispersion was applied to the parts and dried. Next, the component was coated with a silver dispersion and dried. Finally, the component was mounted on a substrate having the terminals described herein and shown in Figure 1A.

[0096] Multiple components (12) consisting of 220μF / 2.5V capacitors were fabricated in this manner and encapsulated in standard silica epoxy resin. Next, various electrical properties of the resulting components were tested. The results are presented in the table below.

[0097] [Table 1]

[0098] The impedance of the capacitor in Example 1 was also tested at various frequencies. Figure 5 shows a graph of the absolute value of the impedance (|Z|) of Example 1 against frequency, compared to a standard capacitor ("Comparison"). As shown, the impedance improvement due to the parasitic inductance associated with the capacitor was substantially reduced at higher frequencies compared to the standard capacitor. For example, at 100 MHz, there was a decrease of approximately 66% in impedance (parasitic inductance), and thus the impedance was lower than 0.7 ohms. Figure 6 also shows the modeled and measured insertion loss scattering parameter (S) for Example 1. 21 The results show that this capacitor exhibits high attenuation over a wide frequency range, including over 50 dB in the frequency range of approximately 0.1 MHz to 500 MHz. Furthermore, even in the high frequency range of 500 MHz to 10 GHz, this capacitor still maintains attenuation greater than approximately 30 dB, making it readily usable for DC power filtering applications.

[0099] These and other modifications and variations of the present invention can be implemented by those skilled in the art without departing from the spirit and scope of the invention. Furthermore, it should be understood that the various embodiments are interchangeable, either in whole or in part. Moreover, those skilled in the art will understand that the above description is merely illustrative and not intended to limit the invention, and that further details are provided in such appended claims.

Claims

Claim 1 A solid electrolytic capacitor comprising: a sintered anode body containing tantalum, a dielectric containing tantalum pentoxide covering the anode body, a solid electrolyte covering the dielectric, and an external coating covering the solid electrolyte, the solid electrolyte including an inner layer containing in-situ polymerized conductive polymer and / or intrinsically conductive polymer and an outer layer containing pre-polymerized conductive polymer particles, further wherein the external coating contains pre-polymerized conductive polymer particles, the capacitor element defining opposing first and second ends and opposing upper and lower surfaces, a first exposed anode lead portion extending from the first end of the capacitor element, a first anode terminal electrically connected to the first exposed anode lead portion, a second exposed anode lead portion extending from the second end of the capacitor element, a second anode terminal spaced from the first anode terminal and electrically connected to the second exposed anode lead portion, a housing exposing only the lower surfaces of the first anode terminal, the second anode terminal, or both, and a planar cathode terminal positioned adjacent to the lower surface of the capacitor element and electrically connected to the solid electrolyte. The solid electrolytic capacitor according to claim 1, wherein: the housing surrounds the capacitor element and exposes only the lower surface of the planar cathode terminal; a continuous anode lead extends from the first and second ends of the capacitor element, thereby defining the first and second exposed anode lead portions; the exposed lower surface of the planar cathode terminal is substantially coplanar with the exposed lower surfaces of the first and second anode terminals; and the distance from the first and second exposed anode lead portions to the lower surface of the capacitor element is from about 0.1 millimeter to about 1 millimeter. Claim 2 The solid electrolytic capacitor according to claim 1, wherein the first anode terminal, the second anode terminal, or both include a planar portion substantially parallel to the lower surface of the capacitor element. Claim 3 The solid electrolytic capacitor according to claim 1, wherein the first anode terminal, the second anode terminal, or both of them include a planar portion existing on substantially the same plane as the planar cathode terminal.

4. The solid electrolytic capacitor according to claim 1, wherein the planar cathode terminal is substantially parallel to the lower surface of the capacitor element.

5. The solid electrolytic capacitor according to claim 1, wherein the conductive polymer includes poly(3,4-ethylenedioxythiophene) or a derivative thereof.

6. The anode body is formed from valve metal powder having a specific charge of about 5,000 to about 100,000 μF ＊ The solid electrolytic capacitor according to claim 1, which is formed from valve metal powder having a specific charge of V / g.

7. The anode body is formed from valve metal powder having a specific charge of about 100,000 to about 600,000 μF ＊ The solid electrolytic capacitor according to claim 1, which is formed from valve metal powder having a specific charge of V / g.

8. The solid electrolytic capacitor according to claim 1, which exhibits an impedance of about 1 ohm or less over a frequency range of about 1 kHz to about 100 MHz.

9. A solid electrolytic capacitor according to claim 1, exhibiting an attenuation (S ２１ parameter) of about 40 dB or more over a frequency range from about 0.1 MHz to about 500 MHz. ２１ parameter)

10. A solid electrolytic capacitor according to claim 1, which exhibits an attenuation (S ２１ parameter) of about 20 dB or more over a frequency range of about 500 MHz to about 10 GHz. ２１ parameter)

11. The solid electrolytic capacitor according to claim 1, which exhibits an ESR of about 800 megaohms or less when determined at an operating frequency of 100 kHz and a temperature of 23°C.

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