Tantalum capacitors for increased stability

Abstract

A solid electrolytic capacitor is provided, comprising a capacitor element. The capacitor element includes an anode body comprising tantalum, a dielectric disposed on the anode body, and a solid electrolyte disposed on the dielectric. The solid electrolyte includes an inherently conductive polymer containing repeating thiophene units. Furthermore, the capacitor exhibits a dielectric strength of about 0.6 volts / nanometer or greater. The capacitor also exhibits a charge / discharge capacitance after being subjected to 3,000 cycles of surge voltage and an initial capacitance before being subjected to the surge voltage, with the ratio of the charge / discharge capacitance to the initial capacitance being about 0.75 to 1.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 945,913, filed December 10, 2019, and U.S. Provisional Patent Application No. 62 / 947,014, filed December 12, 2019, which are incorporated by reference in their entireties. [Background technology]

[0002] Tantalum capacitors are typically fabricated by pressing tantalum powder around metal leads, sintering the pressed part, anodizing the sintered anode, and then applying a solid electrolyte. Conductive polymers are often used as the solid electrolyte due to their advantageous low equivalent series resistance (ESR) and "non-burn / non-ignition" failure mode. For example, such electrolytes can be formed by in-situ chemical polymerization of 3,4-dioxythiophene monomer (EDOT) in the presence of a catalyst and dopant. However, conventional capacitors using in-situ polymerized polymers have relatively high leakage currents (DCL) and tend to fail at high voltages, such as those experienced during fast switching or operating current spikes. In an attempt to overcome these issues, dispersions formed from a composite of poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonate) (PEDOT:PSS) have also been used. While PEDOT:PSS dispersions can provide improved leakage current values, other problems nonetheless remain. For example, one problem with polymer slurry-based capacitors is that they can exhibit relatively poor capacitance stability when subjected to repeated voltage charge cycles. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, a need exists for improved solid electrolytic capacitors that exhibit relatively stable electrical properties. [Means for solving the problem]

[0004] According to one embodiment of the present invention, a solid electrolytic capacitor is disclosed that includes a capacitor element. The capacitor element includes an anode body including tantalum, a dielectric disposed on the anode body, and a solid electrolyte disposed on the dielectric. The solid electrolyte includes an inherently conductive polymer including repeating thiophene units. Furthermore, the capacitor exhibits a dielectric strength of about 0.6 volts / nanometer or greater. The capacitor also exhibits a charge / discharge capacitance after being subjected to 3,000 cycles of a surge voltage and an initial capacitance before being subjected to the surge voltage, wherein the ratio of the charge / discharge capacitance to the initial capacitance is about 0.75 to 1.

[0005] Other features and aspects of the present invention are set forth in more detail below.

[0006] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment of a capacitor of the assembly of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of another embodiment of a capacitor of the assembly of the present invention. [Figure 3] FIG. 3 is a cross-sectional view of yet another embodiment of a capacitor of the assembly of the present invention. [Figure 4] FIG. 4 is a top view of yet another embodiment of a capacitor of the assembly of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or components of the invention.

[0009] It will be appreciated by those skilled in the art that this discussion is a description of exemplary embodiments only and is not intended to limit the broader aspects of the invention, which broader aspects may be embodied in the exemplary configurations.

[0010] Generally speaking, the present invention relates to a solid electrolytic capacitor comprising a capacitor element including an anode body comprising tantalum, a dielectric disposed on the anode body, and a solid electrolyte disposed on the dielectric, the solid electrolyte comprising a conductive polymer containing repeating thiophene units. The inventors have discovered that by selectively controlling certain properties of the capacitor element and the materials from which the capacitor element is formed, capacitors can be formed with a high degree of dielectric strength, thereby improving capacitance stability. "Dielectric strength" generally refers to the ratio of a capacitor's "breakdown voltage" (the voltage at which the capacitor breaks down, in volts, "V") to the thickness of the dielectric (in nanometers, "nm"). Capacitors typically exhibit a dielectric strength of about 0.6 V / nm or greater, in some embodiments about 0.65 V / nm or greater, in some embodiments about 0.7 V / nm or greater, in some embodiments about 0.75 to about 1 V / nm, and in some embodiments about 0.8 to about 0.9 V / nm. The capacitor may exhibit a relatively high breakdown voltage, for example, about 55 volts or more, in some embodiments about 65 volts or more, in some embodiments about 85 volts or more, in some embodiments about 90 volts or more, in some embodiments about 95 volts or more, and in some embodiments about 100 volts to about 300 volts, as determined by increasing the applied voltage in 3 volt increments until the leakage current reaches 1 mA. While the thickness may generally vary depending on the specific location of the anode body, the "dielectric thickness" for purposes of determining dielectric strength is generally considered to be the maximum thickness of the dielectric, and is typically about 60 nm or more, in some embodiments about 60 to about 500 nm, in some embodiments about 80 to about 350 nm, and in some embodiments about 100 to about 300 nm.

[0011] The resulting capacitor can maintain stable electrical properties (e.g., capacitance) under a wide range of different conditions. For example, the ratio of capacitance (charge / discharge capacitance) after repeated cycles of a surge voltage to the initial capacitance value before such testing can be about 0.75 to 1, in some embodiments about 0.8 to 1, in some embodiments about 0.85 to 1, in some embodiments about 0.9 to 1, in some embodiments 0.91 to 0.99, and in some embodiments 0.92 to 0.99. The surge voltage can be applied for 1,000 to 16,000 cycles (e.g., 1,000, 2,000, 3,000, 4,000, 5,000, 8,000, 12,000, or 16,000 cycles). For example, after 3,000 cycles, the capacitor may exhibit a charge / discharge capacitance of 0.75-1, in some embodiments, about 0.95-1, in some embodiments, about 0.96-1, and in some embodiments, about 0.97-1.

[0012] Additionally, the capacitance may also remain stable after exposure to elevated temperatures, such as about 80°C or higher, in some embodiments, from about 100°C to about 150°C, and in some embodiments, from about 105°C to about 130°C (e.g., 105°C or 125°C), for a substantial period of time, such as about 100 hours or more, in some embodiments, from about 150 hours to about 3,000 hours (e.g., 3,000 hours). In one embodiment, for example, the ratio of capacitance after 3,000 hours of exposure to elevated temperatures (e.g., 105°C) to the initial capacitance value (e.g., at 23°C) is about 0.7 to 1, in some embodiments, about 0.8 to 1, in some embodiments, about 0.9 to 1, and in some embodiments, 0.91 to 0.99. Actual capacitance values ​​(dry) may vary, but are typically about 1 millifarad per square centimeter (mF / cm) measured at a frequency of 120 Hz. 2 ) or more, and in some embodiments, about 2 mF / cm 2 In some embodiments, the range is about 5 to about 50 mF / cm 2 In some embodiments, from about 8 to about 20 mF / cm2 is.

[0013] In addition to the above, the present capacitors may also exhibit other improved electrical properties. For example, after being subjected to an applied voltage (e.g., 120 volts) for about 30 minutes to about 20 hours, in some embodiments, about 1 hour to about 18 hours, and in some embodiments, about 4 hours to about 16 hours, the present capacitors may exhibit a leakage current (DCL) of only 100 microamperes (μA) or less, in some embodiments, about 70 μA or less, and in some embodiments, about 1 to about 50 μA. Notably, the present capacitors may exhibit such low DCL values ​​even under dry conditions, as described above. The present capacitors may also exhibit a relatively low equivalent series resistance (ESR), such as about 200 milliohms, in some embodiments, less than about 150 milliohms, in some embodiments, about 0.01 to about 125 milliohms, and in some embodiments, about 0.1 to about 100 milliohms, measured at an operating frequency of 100 kHz and a temperature of 23°C. The capacitors may also exhibit such ESR values ​​even after exposure to temperatures of about 80°C or higher, in some embodiments from about 100°C to about 150°C, and in some embodiments from about 105°C to about 130°C (e.g., 105°C or 125°C), for a substantial period of time, such as about 100 hours or more, in some embodiments from about 150 hours to about 3,000 hours (e.g., 3,000 hours). In one embodiment, for example, the ratio of the ESR of the capacitor after 3,000 hours of exposure to a high temperature (e.g., 105°C) to the initial ESR value of the capacitor (e.g., at 23°C) is about 2.0 or less, in some embodiments about 1.5 or less, and in some embodiments, 1.0 to about 1.3.

[0014] It is also believed that the dissipation factor of the capacitor can be maintained at a relatively low level. The dissipation factor generally refers to the loss that occurs in a capacitor and is usually expressed as a percentage of ideal capacitor performance. For example, the dissipation factor of the present capacitors is typically about 250% or less, in some embodiments about 200% or less, and in some embodiments, from about 1% to about 180%, measured at a frequency of 120 Hz.

[0015] Various embodiments of the capacitor will now be described in more detail.

[0016] I. Capacitor element A. Anode body The capacitor element includes an anode comprising a dielectric formed on an anode body. The anode body may be in the form of a sheet, foil, mesh, pellet, etc. Regardless of its form, the anode body is typically formed from tantalum. In one embodiment, for example, the anode body may be in the form of a pellet formed from tantalum powder. The tantalum powder may be formed from a reduction process 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 provided in the form of a liquid, gas (e.g., hydrogen), or solid, such as a metal (e.g., sodium), metal alloy, or metal salt. For example, in one embodiment, a tantalum salt (e.g., TaCl5) may be heated at 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, which may be reduced in the presence of a gaseous reducing agent (e.g., hydrogen). Further details of such reduction reactions are described in WO-2014 / 199480 by Maeshima et al. After reduction, the product can be cooled, crushed, and washed to form a powder.

[0017] When used, the specific charge of the powder typically ranges from about 2,000 to about 600,000 microFarad-Volts per gram (μF·V / g) depending on the desired application. For example, in some embodiments, high-charge powders can be used having a specific charge of about 100,000 to about 600,000 μF·V / g, in some embodiments, about 120,000 to about 500,000 μF·V / g, and in some embodiments, about 150,000 to about 400,000 μF·V / g. In other embodiments, low-charge powders can be used having a specific charge of about 2,000 to about 100,000 μF·V / g, in some embodiments, about 5,000 to about 80,000 μF·V / g, and in some embodiments, about 10,000 to about 70,000 μF·V / g. As is known in the art, the specific charge can be determined by multiplying the capacitance by the anodization voltage used and then dividing this product by the weight of the anodized electrode body. The powder may be a free-flowing, fine powder containing primary particles. The primary particles of the powder typically have a median diameter (D50) of about 5 to about 500 nanometers, in some embodiments about 10 to about 400 nanometers, and in some embodiments about 20 to about 250 nanometers, as determined using, for example, a laser particle size distribution analyzer (e.g., LS-230) manufactured by Beckman Coulter Corporation, optionally after subjecting the particles to 70 seconds of ultrasonic vibration. The primary particles typically have a three-dimensional particle shape (e.g., spherical or angular). Such particles typically have a relatively low "aspect ratio," i.e., the average diameter or width of the particle divided 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 primary particles, the powder may contain other types of particles, such as secondary particles formed by aggregation (or agglomeration) of primary particles. Such secondary particles may have a median diameter (D50) of from about 1 to about 500 micrometers, and in some embodiments, from about 10 to about 250 micrometers.

[0018] The aggregation of the particles can be carried out by heating the particles and / or by using a binder, for example, at a temperature 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. Suitable binders also include, for example, poly(vinyl butyral); poly(vinyl acetate); poly(vinyl alcohol); poly(vinylpyrrolidone); cellulose polymers such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and methylhydroxyethyl cellulose; 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; and fatty acids and waxes such as stearic acid and other soap fatty acids, vegetable waxes, microcrystalline waxes (refined paraffin), and the like.

[0019] The resulting powder can be compressed to form pellets using any conventional powder pressing equipment. For example, a press can be used that is a single-station compression press containing a die and one or more punches. Alternatively, an anvil-type compression press can be used, which uses only a die and a single lower punch. Single-station compression presses are available in several basic types, such as cam presses, toggle / knuckle presses, and eccentric / crank presses, with various capabilities such as single-action, double-action, floating die, moving platen, opposed ram, screw, impact, hot pressing, coining, or sizing. The powder can be compressed around an anode lead, which can be in the form of a wire, sheet, or the like. The lead can extend longitudinally from the anode body and can be formed from any conductive material, such as tantalum, niobium, aluminum, hafnium, titanium, and the like, as well as their conductive oxides and / or nitrides. Connection of the lead to the anode body can also be achieved using other known techniques, such as by welding the lead to the anode body or embedding it within the anode body during formation (e.g., before pressing and / or sintering).

[0020] After pressing, the binder can be removed by heating the pellets under vacuum at a certain temperature (e.g., about 150°C to about 500°C) for several minutes. Alternatively, the binder can be removed by contacting the pellets with an aqueous solution, such as that described in U.S. Patent No. 6,197,252 to Bishop et al. The pellets are then sintered to form a porous, monolithic member. The pellets are typically sintered at temperatures of about 700°C to about 1800°C, in some embodiments about 800°C to about 1700°C, and in some embodiments about 900°C to about 1400°C, for about 5 minutes to about 100 minutes, and in some embodiments about 8 minutes to about 15 minutes. This can be done in one or more steps. If desired, sintering can be done in an atmosphere that limits the migration of oxygen atoms to the anode body. For example, sintering can be done in a reducing or inert atmosphere, such as in a vacuum, an inert gas, or hydrogen. The reducing atmosphere may be at a pressure from about 10 Torr to about 2000 Torr, in some embodiments from about 100 Torr to about 1000 Torr, and in some embodiments, from about 100 Torr to about 930 Torr. Mixtures of hydrogen and other gases, such as argon or nitrogen, can also be used.

[0021] B. Dielectric The anode is also coated with a dielectric. As noted above, the dielectric is formed by anodizing the anode, such that a dielectric layer is formed on and / or within the anode. For example, a tantalum (Ta) anode can be anodized to tantalum pentoxide (Ta2O5). Typically, anodization is performed by first applying an electrolyte to the anode, e.g., by immersing the anode in the electrolyte. The electrolyte is generally in the form of a liquid, such as a solution (e.g., aqueous or non-aqueous), dispersion, or melt. Solvents commonly used in electrolytes include water (e.g., deionized water); ethers (e.g., diethyl ether, tetrahydrofuran); glycols (e.g., ethylene glycol, propylene glycol, etc.); alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, and butanol); triglycerides; ketones (e.g., acetone, methyl ethyl ketone, and methyl isobutyl ketone); esters (e.g., ethyl acetate, butyl acetate, diethylene glycol ether acetate, and methoxypropyl acetate); amides (e.g., dimethylformamide, dimethylacetamide, dimethylcapryl / capric 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 the like. The solvent(s) may comprise from about 50% to about 99.9% by weight of the electrolyte, in some embodiments, from about 75% to about 99% by weight, and in some embodiments, from about 80% to about 95% by weight. Although not required, the use of an aqueous solvent (e.g., water) is often desirable to promote oxide formation. Indeed, water may comprise about 1% by weight or more, in some embodiments 10% by weight or more, in some embodiments about 50% by weight or more, in some embodiments about 70% by weight or more, and in some embodiments about 90% to about 100% by weight of the solvent(s) used in the electrolyte.

[0022] The electrolyte is electrically conductive and may have a conductivity of 1 milliSiemens / centimeter (mS / cm) or greater, in some embodiments 30 mS / cm or greater, and in some embodiments, from about 40 mS / cm to about 100 mS / cm, measured at a temperature of 25° C. To increase the conductivity of the electrolyte, ionic compounds that can dissociate in the solvent to form ions are typically used. Suitable ionic compounds for this purpose include, for example, acids such as nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, boronic acid, etc.; carboxylic acids such as acrylic acid, methacrylic acid, malonic acid, succinic acid, salicylic acid, sulfosalicylic acid, adipic acid, maleic acid, malic acid, oleic acid, gallic acid, tartaric acid, citric acid, formic acid, acetic acid, glycolic acid, oxalic acid, propionic acid, phthalic acid, isophthalic acid, glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, itaconic acid, trifluoroacetic acid, barbituric acid, cinnamic acid, benzoic acid, 4-hydroxybenzoic acid, Examples of suitable ionic compounds include organic acids such as aminobenzoic acid; sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, trifluoromethanesulfonic acid, styrenesulfonic acid, naphthalenedisulfonic acid, hydroxybenzenesulfonic acid, dodecylsulfonic acid, and dodecylbenzenesulfonic acid; and polymeric acids such as poly(acrylic) or poly(methacrylic) acids and their copolymers (e.g., maleic-acrylic, sulfonic-acrylic, and styrene-acrylic copolymers), carrageenic acid, carboxymethylcellulose, and alginic acid. The concentration of the ionic compound is selected to achieve the desired conductivity. For example, the acid (e.g., phosphoric acid) may comprise from about 0.01% to about 5% by weight of the electrolyte, in some embodiments, from about 0.05% to about 0.8% by weight, and in some embodiments, from about 0.1% to about 0.5% by weight. If desired, a blend of multiple ionic compounds can be used in the electrolyte.

[0023] To form the dielectric, a current is typically passed through the electrolyte while it is in contact with the anode body. The thickness of the dielectric layer is controlled by the value of the formation voltage. For example, the power supply can first be set in constant current mode until the required voltage is reached. The power supply can then be switched to potentiostatic mode to ensure the desired dielectric thickness is formed over the entire surface of the anode. Of course, other known methods, such as pulse or step potentiostatic methods, can also be used. The voltage at which the anodization is performed is typically in the range of about 4 to about 250 V, in some embodiments about 5 to about 200 V, and in some embodiments about 10 to about 150 V. During oxidation, the electrolyte can be maintained at an elevated temperature, for example, above about 30°C, in some embodiments about 40°C to about 200°C, and in some embodiments about 50°C to about 100°C. Anodization can also be performed at or below ambient temperature. The resulting dielectric layer can be formed on the surface of the anode and within its pores.

[0024] Although not required, in some embodiments, the dielectric layer can have a differentiated thickness throughout the anode, in that it has a first portion disposed on the outer surface of the anode and a second portion disposed on the inner surface of the anode. In such embodiments, the first portion is selectively formed to have a greater thickness than the second portion. However, it should be understood that the thickness of the dielectric layer need not be uniform within a particular region. For example, some portions of the dielectric layer adjacent to the outer surface may actually be thinner than some portions of the layer at the inner surface, and vice versa. Nevertheless, the dielectric layer can be formed such that at least a portion of the layer at the outer surface has a greater thickness than at least a portion of the layer at the inner surface. While the actual difference in these thicknesses can vary depending on the particular application, the ratio of the thickness of the first portion to the thickness of the second portion is typically about 1.2 to about 40, in some embodiments about 1.5 to about 25, and in some embodiments about 2 to about 20.

[0025] A multi-step process can be used to form dielectric layers of differentiated thicknesses. In each step of the process, a sintered anode is anodized to form a dielectric layer (e.g., tantalum pentoxide). During the first step of anodization, a relatively low formation voltage, e.g., in the range of about 1 to about 90 volts, in some embodiments about 2 to about 50 volts, and in some embodiments about 5 to about 20 volts, is typically used to ensure that the desired dielectric thickness is achieved for the interior region. The sintered body can then be anodized in the second step of the process to increase the dielectric thickness to the desired level. This is generally accomplished by anodizing in an electrolyte at a formation voltage higher than that used during the first step, e.g., in the range of about 50 to about 350 volts, in some embodiments about 60 to about 300 volts, and in some embodiments about 70 to about 200 volts. During the first and / or second stages, the electrolyte may be maintained at a temperature within the range of from about 15°C to about 95°C, in some embodiments from about 20°C to about 90°C, and in some embodiments, from about 25°C to about 85°C.

[0026] The electrolytes used during the first and second stages of the anodization process can be the same or different. However, typically, the electrolyte used during at least one stage of the dielectric growth process comprises an ionic compound as described above. In one particular embodiment, it may be desirable for the electrolyte used in the second stage to have a lower ionic conductivity than the electrolyte used in the first stage to prevent the formation of a significant oxide film on the inner surface of the anode. In this regard, the electrolyte used during the first stage can include an ionic compound that is an acid, such as nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, boronic acid, and the like. Such electrolytes can have a conductivity, measured at a temperature of 25°C, of ​​about 0.1 to about 100 mS / cm, in some embodiments, about 0.2 to about 20 mS / cm, and in some embodiments, about 1 to about 10 mS / cm. The electrolyte used during the second stage can also include an ionic compound that is a salt of a weak acid, such that the hydronium ion concentration increases within the pores as a result of charge passage within the pores. Ion transport or diffusion occurs, causing weak acid anions to migrate into the pores as needed to balance the charge. As a result, the concentration of the primary conductive species (hydronium ions) decreases as an equilibrium is formed between hydronium ions, acid anions, and undissociated acid, resulting in the formation of non-conductive species. The decrease in the concentration of conductive species results in a relatively high voltage drop in the electrolyte, which prevents further anodization in the interior, while a thicker oxide layer builds up on the exterior at higher formation voltages in successively higher conductivity regions. Suitable weak acid salts include, for example, ammonium or alkali metal (e.g., sodium, potassium, etc.) salts of boric acid, boronic acid, acetic acid, oxalic acid, lactic acid, adipic acid, and the like. Particularly suitable salts include sodium tetraborate and ammonium pentaborate. Such electrolytes typically have a conductivity measured at 25°C of about 0.1 to about 20 mS / cm, in some embodiments about 0.5 to about 10 mS / cm, and in some embodiments about 1 to about 5 mS / cm.

[0027] If desired, each step of anodization can be repeated one or more cycles to achieve the desired dielectric thickness. Additionally, the anode can be rinsed or washed with other solvents (e.g., water) after the first and / or second steps to remove the electrolyte.

[0028] C. Precoat If desired, a precoat can be used that is disposed on the dielectric and positioned between the dielectric and the solid electrolyte. The precoat has the following general formula (V):

[0029] [ka]

[0030] (In the formula, Z 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.), and at least one of R1, R2, and R3 is 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); X is an organic or inorganic functional group such as glycidyl, glycidyloxy, mercapto, amino, vinyl, etc. These compounds may include organometallic compounds such as compounds having the formula:

[0031] In some embodiments, at least one of R1, R2, and R3 in Formula (II) can be hydroxyalkyl (e.g., OCH3). For example, each of R1, R2, and R3 can be hydroxyalkyl. However, in other embodiments, R1 can be alkyl (e.g., CH3), and R2 and R3 can be hydroxyalkyl (e.g., OCH3).

[0032] In some embodiments, X may be an amino group. Suitable amino-functional organosilane compounds include, for example, those represented by the following general formula (II):

[0033] [ka]

[0034] (In the formula, R1, R2, and R3 are as defined above; R4 and R5 are independently hydrogen, alkyl, independently alkyl, alkenyl, aryl, heteroaryl, cycloalkyl, heterocyclyl, halo, haloalkyl, hydroxyalkyl, or N, R4, and R5 together with one or more additional atoms form a ring structure (e.g., heteroaryl or heterocyclyl); Z is an organic group linking the nitrogen atom to the silicon atom, such as alkyl (e.g., ethyl or propyl), aryl (e.g., phenyl), etc. Examples include monoamine-functional silanes having the formula:

[0035] Examples of monoaminofunctional organosilane compounds include primary amine compounds (e.g., 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3-aminopropyltris(methoxyethoxy)silane, 11-aminoundecyltriethoxysilane, 2(4-pyridylethyl)triethoxysilane, 2-(trimethoxysilylethyl)pyridine, N-(3-trimethoxysilylpropyl)pyrrole, 3-(m-aminophenoxypropyltrimethoxysilane, aminopropylsilanetriol, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyldimethylethoxysilane, etc.); secondary amine compounds (e.g., N-butylaminopropyltrimethoxysilane, N-ethylaminoisobutyltrimethoxysilane, etc.); Silanes, n-methylaminopropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, 3-(N-allylamino)propyltrimethoxysilane, cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminopropyltrimethoxysilane, N-ethylaminoisobutylmethyldiethoxysilane, (phenylaminoethyl)methyldiethoxysilane, N-phenylaminomethytrimethoxysilane, N-methylaminopropylmethyldimethoxysilane, etc.; tertiary amine compounds (e.g., bis(2-hydroxyethyl)3-aminopropyltriethoxysilane, diethylaminomethyltriethoxysilane, (N,N-diethyl-3-aminopropyl)trimethoxysilane, etc.); and combinations thereof. Furthermore, if desired, additional groups may be attached to the nitrogen atom to make the compound a quaternary amine-functional silane compound.

[0036] The following general formula (III):

[0037] [ka]

[0038] (In the formula, R1, R2, R3, R4, and R5 are as defined above; Z1 is an organic group that connects the nitrogen atom to the silicon atom, and Z2 is an organic group that connects the nitrogen atoms together, such as alkyl (e.g., ethyl or propyl), aryl (e.g., phenyl), etc. Diamino-functional silane compounds having the formula: may also be used. Examples of such diamino-functional silane compounds include, for example, N-(2-aminoethyl)-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(6-aminohexyl)aminomethyl-triethoxysilane, N-(6-aminohexyl)aminopropyltrimethoxysilane, N-(2-aminoethyl)-11-aminoundecyltrimethoxysilane, (aminoethylaminomethyl)-phenethyltrimethoxysilane, N-3-[(amino(polypropyleneoxy)]-aminopropyl ... Examples include butyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylsilanetriol, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, (aminoethylamino)-3-isobutyldimethylmethoxysilane, and the like, and combinations thereof. Triamino-functional compounds such as (3-trimethoxysilylpropyl)-diethylenetrimamine can also be used.

[0039] Of course, as indicated above, other functional groups may also be used. For example, in some embodiments, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2,2-dimethoxy-1-thia-2-silacyclopentane, 11-mercaptoundecyltrimethoxysilane, S-(octanoyl)mercaptopropyltriethoxysilane, 2-(2-pyridylethyl)thiopropyltrimethoxysilane, 2-(4-pyridyl)thiopropyltrimethoxysilane, 3-thiocyanopropyltrimethoxysilane, 2-(3 Sulfur-functional silane compounds such as bis[3-(triethoxysilyl)propyl]tetrasulfide, bis[3-(triethoxysilyl)propyl]disulfide, bis[m-(2-triethoxysilylethyl)tolyl]polysulfide, bis[3-(triethoxysilyl)propyl]thiourea, and the like, and combinations thereof, can be used.

[0040] The particular method for applying the precoat to the capacitor body may vary as desired. In one particular embodiment, the compound is dissolved in an organic solvent and applied as a solution to the component by screen printing, dipping, electrocoating, spraying, or the like. The organic solvent may vary, but is typically an alcohol such as methanol, ethanol, or the like. The organometallic compound may comprise from about 0.1% to about 10% by weight of the solution, in some embodiments from about 0.2% to about 8% by weight, and in some embodiments, from about 0.5% to about 5% by weight. Additionally, the solvent may comprise from about 90% to about 99.9% by weight, in some embodiments from about 92% to about 99.8% by weight, and in some embodiments, from about 95% to about 99.5% by weight of the solution. Once applied, the component may then be dried to remove the solvent therefrom, forming a precoat layer including the organometallic compound.

[0041] D. Solid electrolyte A solid electrolyte is disposed over the dielectric and any precoat, and typically functions as the cathode for the capacitor. Typically, the total thickness of the solid electrolyte is from about 1 to about 50 μm, and in some embodiments, from about 5 to about 20 μm. Typically, the solid electrolyte comprises an inherently conductive polymer having positive charges disposed on the backbone that are at least partially compensated by anions covalently bonded to the polymer. For example, one suitable inherently conductive polymer has the following formula (I):

[0042] [ka]

[0043] (In the formula, R is (CH2) a -O-(CH2) b -L (wherein L is a bond or HC([CH] c H) is) is; 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); M is an anion such as SO3, C(O)O, BF4, CF3SO3, SbF6, N(SO2CF3)2, C4H3O4, ClO4, etc.; X is a cation such as hydrogen, an alkali metal (e.g., lithium, sodium, rubidium, cesium, or potassium), ammonium, etc. The repeating thiophene units may be:

[0044] In one particular embodiment, M in formula (I) indicates that the intrinsically conductive polymer has the following formula (II):

[0045] [ka]

[0046] wherein R and X are as defined above. In formula (I) or (II), a is preferably 1 and b is preferably 3 or 4. Furthermore, X is preferably sodium or potassium.

[0047] If desired, the polymer may be a copolymer containing other types of repeat units. In such embodiments, the repeat units of formula (V) typically constitute at least about 50 mol %, in some embodiments from about 75 mol % to about 99 mol %, and in some embodiments, from about 85 mol % to about 95 mol %, of the total amount of repeat units in the copolymer. Of course, the polymer may be a homopolymer, containing up to 100 mol % of repeat units of formula (I).

[0048] In another embodiment, the inherently conductive polymer has the following general formula (III):

[0049] [ka]

[0050] (In the formula, a and b are as defined above; R5 is an optionally substituted C1-C6 linear or branched alkyl group (e.g., methyl) or a halogen atom (e.g., fluorine); X is a hydrogen atom, an alkali metal (e.g., Li, Na, or K), NH(R 1 )3(wherein, R 1 are each independently a hydrogen atom or an optionally substituted C1-C6 alkyl group, or HNC5H5 It has repeating thiophene units of

[0051] Specific examples of thiophene compounds used to form such repeating units are described in U.S. Pat. No. 9,718,905, and include, for example, sodium 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-ethyl-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-ethyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl ... -propyl-1-propane-sodium sulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propanesulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, Sodium [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-fluoro Sodium 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-propanesulfonate, ammonium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate,[4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, triethylammonium ester, and combinations thereof. Each of the thiophene monomers listed above can be prepared from thieno[3,4-b]-1,4-dioxin-2-methanol and a branched sultone compound by a known method (e.g., Journal of Electroanalytical Chemistry, 443, 217-226 (1998)).

[0052] Intrinsically conductive polymers can be formed by a variety of techniques understood by those skilled in the art. In one particular embodiment, for example, thiophene compounds having the general formula (I) can be polymerized in the presence of an oxidation catalyst. Derivatives of these monomers, such as dimers or trimers of the above compounds, can also be used. The derivatives can be composed of the same or different monomer units and can be used in pure form as well as in mixtures with each other and / or with the monomers. Oxidized or reduced forms of these precursors can also be used. The amount of oxidation catalyst used in the polymerization reaction is not particularly limited, but can be in the range of 1 to 50 moles, more preferably 1 to 20 moles, relative to the number of moles of thiophene compound used as input material. The oxidation catalyst can be a transition metal salt, such as a salt of an inorganic or organic acid containing ammonium, sodium, gold, iron(III), copper(II), chromium(VI), cerium(IV), manganese(IV), manganese(VII), or ruthenium(III) cation. Particularly suitable transition metal salts include halides (e.g., FeCl3 or HAuCl4); salts of other inorganic acids (e.g., Fe(ClO4)3, Fe2(SO4)3, (NH4)2S2O8, or Na3Mo 12 PO 40 ); and salts of organic and inorganic acids containing an organic group. Examples of salts of inorganic acids having an organic group include, for example, C1 to C 20 Iron(III) salts of sulfate monoesters of alkanols (for example, iron(III) salt of lauryl sulfate) are also included. Further, examples of salts of organic acids include, for example, C1-C 20Iron(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); optionally C1-C 20 Examples include iron(III) salts of alkyl-substituted aromatic sulfonic acids (e.g., benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid); iron(III) salts of cycloalkanesulfonic acids (e.g., camphorsulfonic acid); etc. Mixtures of these aforementioned salts can also be used.

[0053] Oxidative polymerization is generally carried out in the presence of one or more solvents. Suitable solvents include, for example, water, glycols (e.g., ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, polyethylene glycol, ethoxydiglycol, dipropylene glycol, etc.); glycol ethers (e.g., methyl glycol ether, ethyl glycol ether, isopropyl glycol ether, etc.); alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, and butanol); ketones (e.g., acetone, methyl ethyl ketone, and methyl isobutyl ketone); esters (e.g., ethyl acetate, butyl acetate, diethylene glycol ether acetate, methoxypropyl acetate, ethylene carbonate, propylene carbonate, etc.); amides (e.g., dimethylformamide, dimethylacetamide, dimethylcapryl / capric fatty acid amide, and N-alkylpyrrolidone); sulfoxides or sulfones (e.g., dimethyl sulfoxide (DMSO) and sulfolane); phenolic compounds (e.g., toluene, xylene, etc.). Water is a particularly suitable solvent for the reaction. The amount of solvent used in this polymerization reaction is not particularly limited, but is preferably 0.1 to 100 times, more preferably 0.1 to 50 times, the weight of the thiophene compound added, as long as the thiophene compound used as a raw material is dissolved in the solvent. The temperature at which the reaction is carried out typically ranges from about -20°C to about 140°C, and in some embodiments, from about 20°C to about 100°C. Once the reaction is complete, any salt impurities can be removed using known purification techniques, such as washing with a solvent, reprecipitation, centrifugal sedimentation, ultrafiltration, dialysis, or ion exchange resin treatment, or a combination thereof.

[0054] Regardless of how they are formed, polymers are considered "intrinsically" conductive to the extent that they have positive charges located on the backbone that are at least partially compensated by anions covalently bonded to the polymer. The polymers may have, for example, a relatively high specific conductivity in the dry state of about 1 Siemens per centimeter (S / cm) or greater, in some embodiments about 10 S / cm or greater, in some embodiments about 25 S / cm or greater, in some embodiments about 40 S / cm or greater, and in some embodiments about 50 to about 500 S / cm. As a result of their inherent conductivity, the solid electrolyte does not require the addition of conventional dopants such as polystyrene sulfonic acid. In fact, the solid electrolyte may be substantially free of such dopants. Nevertheless, it should be understood that dopants can be used in certain embodiments of the present invention. However, if utilized, dopants are typically present in the solid electrolyte in an amount of about 5 wt. % or less, in some embodiments about 2 wt. % or less, and in some embodiments about 1 wt. % or less.

[0055] Polymers are also generally highly soluble in water, allowing them to be applied to the anode more easily and efficiently. Soluble polymers can also more easily impregnate the pores formed by the high specific charge powder, resulting in a solid electrolyte with a "film-like" structure that substantially uniformly coats at least a portion of the anode. This improves the quality of the resulting oxide as well as its surface coverage, thereby enhancing the electrical properties of the capacitor assembly.

[0056] i. Inner layer Solid electrolytes are generally formed from one or more "inner" conductive polymer layers. The term "inner" in this context refers to one or more layers formed from the same material and overlying a dielectric, either directly or via another layer (e.g., a precoat). For example, the one or more inner layers typically comprise an intrinsically conductive polymer, as described above. In one particular embodiment, the one or more inner layers are generally free of extrinsic conductive polymers and are therefore primarily formed from intrinsically conductive polymers. More specifically, the intrinsically conductive polymer may comprise about 50% by weight or more, in some embodiments about 70% by weight or more, and in some embodiments about 90% by weight or more (e.g., 100% by weight) of the one or more inner layers. One or more inner layers can be used. For example, a solid electrolyte typically comprises 2 to 30, in some embodiments 4 to 20, and in some embodiments about 5 to 15 inner layers (e.g., 10 layers).

[0057] The inner layer(s) can be applied in the form of a solution containing a solvent. The concentration of polyaniline can vary depending on the desired viscosity and the particular manner in which the layer is applied to the anode. Typically, however, the polyaniline comprises from about 0.1 to about 10 wt. % of the solution, in some embodiments, from about 0.4 to about 5 wt. %, and in some embodiments, from about 0.5 to about 4 wt. %. Additionally, the solvent(s) comprise from about 90 wt. % to about 99.9 wt. % of the solution, in some embodiments, from about 95 wt. % to about 99.6 wt. %, and in some embodiments, from about 96 wt. % to about 99.5 wt. %. If used, the solution can be applied to the anode using any known technique, such as dipping, casting (e.g., curtain coating, spin coating, etc.), printing (e.g., gravure printing, offset printing, screen printing, etc.), and the like. The resulting conductive polymer layer can be dried and / or washed after application to the anode.

[0058] ii. Outer layer A solid electrolyte can include only an "inner layer" formed from substantially the same material, i.e., an intrinsically conductive polymer. However, in other embodiments, a solid electrolyte can also include one or more optional "outer" conductive polymer layers formed from a different material than the inner layer(s) and disposed on the inner layer(s). For example, one or more outer layers can be formed from an extrinsic conductive polymer. In one particular embodiment, one or more outer layers are formed primarily from such an extrinsic conductive polymer in that they constitute about 50% by weight or more, in some embodiments about 70% by weight or more, and in some embodiments about 90% by weight or more (e.g., 100% by weight) of the respective outer layer. One or more outer layers can be used. For example, a solid electrolyte can include 2 to 30, in some embodiments about 4 to 20, and in some embodiments about 5 to 15 outer layers.

[0059] When used, the extrinsic conductive polymer may be, for example, a polymer having the following formula (IV):

[0060] [ka]

[0061] (In the formula, R7 is linear or branched C1 to C 18 Alkyl groups (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 to C6 12 Cycloalkyl groups (e.g., cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, etc.); C6-C 14Aryl groups (e.g., phenyl, naphthyl, etc.); C7-C 18 aralkyl groups (e.g., benzyl, o-, m-, p-tolyl, 2,3-, 2,4-, 2,5-, 2-6-, 3-4-, 3,5-xylyl, mesityl, etc.); C1-C4 hydroxyalkyl groups, or hydroxyl groups; The polymer may have repeating units of 3,4-ethylenedioxythiophene, where q is an integer from 0 to 8, in some embodiments from 0 to 2, and in one embodiment is 0. In one particular embodiment, "q" is 0 and the polymer is poly(3,4-ethylenedioxythiophene). One commercially suitable example of a monomer suitable for forming such a polymer is 3,4-ethylenedioxythiophene, which is available from Heraeus under the name Clevios™ M.

[0062] Polymers of formula (IV) are generally considered to be "extrinsically" conductive in that they require the presence of a separate counterion that is not covalently bonded to the polymer. The counterion may be a monomeric or polymeric anion that neutralizes the charge of the conductive polymer. The polymeric anion may be, for example, a polymeric carboxylic acid (e.g., polyacrylic acid, polymethacrylic acid, polymaleic acid, etc.); a polymeric sulfonic acid (e.g., polystyrene sulfonic acid (PSS), polyvinyl sulfonic acid, etc.); or the like. The acid may also be a copolymer, such as a copolymer of vinyl carboxylic acid and vinyl sulfonic acid with other polymerizable monomers, such as acrylic acid esters and styrene. Additionally, suitable monomeric anions include, for example, C1-C 20 Alkanesulfonic acids (e.g., dodecanesulfonic acid); aliphatic perfluorosulfonic acids (e.g., trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, or perfluorooctanesulfonic acid); aliphatic C1-C 20 Carboxylic acids (e.g., 2-ethylhexylcarboxylic acid); aliphatic perfluorocarboxylic acids (e.g., trifluoroacetic acid or perfluorooctanoic acid); optionally C1-C 20Examples of suitable counter anions include alkyl-substituted aromatic sulfonic acids (e.g., benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid); cycloalkanesulfonic acids (e.g., camphorsulfonic acid, or tetrafluoroborate, hexafluorophosphate, perchlorate, hexafluoroantimonate, hexafluoroarsenate, or hexachloroantimonate); and the like. Particularly suitable counter anions are polymeric anions such as polymeric carboxylic or sulfonic acids (e.g., polystyrene sulfonic acid (PSS)). The molecular weight of such polymeric anions 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.

[0063] When used, the exogenous conductive polymer may desirably be applied in the form of a dispersion of prepolymerized conductive particles. Such particles typically have an average size (e.g., diameter) of about 1 to about 100 nanometers, in some embodiments about 2 to about 80 nanometers, and in some embodiments about 4 to about 50 nanometers. Particle diameter can be determined using known techniques such as ultracentrifugation, laser diffraction, and the like. The shape of the particles can also vary. In one particular embodiment, for example, the particles are spherical. However, it should be understood that other shapes, such as plates, rods, disks, bars, tubes, irregular shapes, and the like, are also contemplated 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 comprise about 0.1 to about 10 weight percent of the dispersion, in some embodiments about 0.4 to about 5 weight percent, and in some embodiments about 0.5 to about 4 weight percent.

[0064] The dispersion may also contain one or more binders to further enhance the adhesion of the polymer layer and increase the stability of the particles in the dispersion. The binder may be of organic nature, such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyacrylic esters, polyacrylic amides, polymethacrylic esters, polymethacrylic amides, polyacrylonitrile, styrene / acrylic esters, vinyl acetate / acrylic esters, and ethylene / vinyl acetate copolymers, polybutadiene, polyisoprene, polystyrene, polyethers, polyesters, polycarbonates, polyurethanes, polyamides, polyimides, polysulfones, melamine formaldehyde resins, epoxide resins, silicone resins, or cellulose. Crosslinking agents may also be used to enhance the adhesive capabilities of the binder. Such crosslinking agents can 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, which can include subsequent crosslinking.

[0065] A dispersant can also be used to facilitate application of the layer to the anode. Suitable dispersants include solvents such as 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), chlorinated 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 above solvents. A particularly suitable dispersant is water.

[0066] In addition to those listed above, other components may also be used in the dispersion. For example, conventional fillers having dimensions 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, silicates, silica, calcium or barium sulfate, aluminum hydroxide, glass fibers or glass spheres, wood flour, cellulose powder, carbon black, conductive polymers, and the like. The filler may be introduced into the dispersion in powder form, but may also be present in other forms, such as fibers.

[0067] Surface-active substances such as ionic or nonionic surfactants can also be used in the dispersion. Additionally, adhesives such as organofunctional silanes or their hydrolyzates, e.g., 3-glycidoxypropyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, or octyltriethoxysilane, can be used. The dispersion can 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 Conductivity-increasing additives may also be included, such as sulfoxides (e.g., sulfolane (tetramethylene sulfone) or dimethyl sulfoxide (DMSO)), sugars or sugar derivatives (e.g., sucrose, glucose, fructose, or lactose), sugar alcohols (e.g., sorbitol or mannitol), furan derivatives (e.g., 2-furancarboxylic acid or 3-furancarboxylic acid), alcohols (e.g., ethylene glycol, glycerol, di- or triethylene glycol).

[0068] The dispersion can be applied using a variety of known techniques, such as by spin coating, impregnation, pouring, drop application, injection, spraying, doctor blade application, brush application, printing (e.g., inkjet, screen, or pad printing), or immersion. The viscosity of the dispersion is typically from about 0.1 to about 100,000 mPa·sec (100 s -1 (measured at a shear rate of 1000 mPa·sec), in some embodiments, from about 1 to about 10,000 mPa·sec, in some embodiments, from about 10 to about 1,500 mPa·sec, and in some embodiments, from about 100 to about 1000 mPa·sec.

[0069] If desired, hydroxyl-functional nonionic polymers can also be used in one or more outer layers of the solid electrolyte. The term "hydroxyl-functional" generally means that the compound contains at least one hydroxyl functional group or is capable of possessing such functionality in the presence of a solvent. While not intending to be limited by theory, it is believed that the use of hydroxyl-functional polymers with certain molecular weights can minimize the possibility of chemical degradation at high voltages. For example, the molecular weight of the hydroxyl-functional polymer can be about 100 to 10,000 grams / mole, in some embodiments about 200 to 2,000 grams / mole, in some embodiments about 300 to about 1,200 grams / mole, and in some embodiments about 400 to about 800 grams / mole.

[0070] Generally, any of a variety of hydroxy-functional nonionic polymers can be used for this purpose. For example, in one embodiment, the hydroxy-functional polymer is a polyalkylene ether. Examples of polyalkylene ethers include polyalkylene glycols (e.g., polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyepichlorohydrin, etc.), polyoxetanes, polyphenylene ethers, polyether ketones, and the like. Polyalkylene ethers are typically primarily linear nonionic polymers with terminal hydroxy groups. Polyethylene glycol, polypropylene glycol, and polytetramethylene glycol (polytetrahydrofuran) are particularly suitable, and are prepared by the polyaddition of ethylene oxide, propylene oxide, or tetrahydrofuran to water. Polyalkylene ethers can be prepared from diols or polyols by polycondensation reactions. The diol component can be selected in particular from saturated or unsaturated, branched or unbranched aliphatic or aromatic dihydroxy compounds containing 5 to 36 carbon atoms, such as pentane-1,5-diol, hexane-1,6-diol, neopentyl glycol, bis-(hydroxymethyl)-cyclohexane, bisphenol A, dimer diols, hydrogenated dimer diols, or even mixtures of the abovementioned diols. Furthermore, polyhydric alcohols, such as glycerol, di- and polyglycerol, trimethylolpropane, pentaerythritol, or sorbitol, can also be used in the polymerization reaction.

[0071] In addition to those mentioned above, other hydroxy-functional nonionic polymers can be used in the present invention. Some examples of such polymers include, for example, ethoxylated alkylphenols; ethoxylated or propoxylated C-C alkylphenols; 24 Aliphatic alcohols; general formula: CH3-(CH2) 10-16 -(O-C2H4) 1-25Polyoxyethylene glycol alkyl ethers having —OH (e.g., octaethylene glycol monododecyl ether and pentaethylene glycol monododecyl ether); general formula: CH3—(CH2) 10-16 -(O-C3H6) 1-25 Polyoxypropylene glycol alkyl ethers having —OH; the following general formula: CH 17 -(C6H4)-(O-C2H4) 1-25 Polyoxyethylene glycol octylphenol ethers having —OH (e.g., Triton® X-100); 19 -(C6H4)-(O-C2H4) 1-25 Polyoxyethylene glycol alkylphenol ethers with -OH (e.g., nonoxynol-9); C8-C 24 Polyoxyethylene glycol esters of fatty acids, such as polyoxyethylene glycol sorbitan alkyl esters (e.g., polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monooleate, PEG-20 methyl glucose distearate, PEG-20 methyl glucose sesquistearate, PEG-80 castor oil, PEG-20 castor oil, PEG-3 castor oil, PEG-600 dioleate, and PEG-400 dioleate), and polyoxyethylene glycerol alkyl esters (e.g., polyoxyethylene-23 glycerol laurate, and polyoxyethylene-20 glycerol stearate); C8 to C9 24Polyoxyethylene glycol ethers of fatty acids (e.g., polyoxyethylene-10 cetyl ether, polyoxyethylene-10 stearyl ether, polyoxyethylene-20 cetyl ether, polyoxyethylene-10 oleyl ether, polyoxyethylene-20 oleyl ether, polyoxyethylene-20 isohexadecyl ether, polyoxyethylene-15 tridecyl ether, and polyoxyethylene-6 tridecyl ether); block copolymers of polyethylene glycol and polypropylene glycol (e.g., Poloxamers); and the like, and mixtures thereof.

[0072] The hydroxy-functional nonionic polymer can be incorporated into the outer layer in a variety of different ways. For example, in some embodiments, the nonionic polymer can simply be incorporated into a dispersion of the exogenous conductive polymer. In such embodiments, the concentration of the nonionic polymer in the layer can be from about 1% to about 50% by weight, in some embodiments, from about 5% to about 40% by weight, and in some embodiments, from about 10% to about 30% by weight. However, in other embodiments, the nonionic polymer can be applied after the initial outer layer(s) have been formed. In such embodiments, the technique used to apply the nonionic polymer can vary. For example, the nonionic polymer can be applied in the form of a liquid solution using various methods, such as impregnation, dipping, pouring, dripping, injecting, spraying, spreading, painting, or printing, e.g., inkjet or screen printing. Solvents known to those skilled in the art, such as water, alcohol, or mixtures thereof, can be used in the solution. The concentration of the nonionic polymer in such solutions typically ranges from about 5% to about 95% by weight of the solution, in some embodiments from about 10% to about 70% by weight, and in some embodiments, from about 15% to about 50% by weight. If desired, such solutions may be entirely free of conductive polymer. For example, the conductive polymer may constitute up to about 2% by weight of the solution, in some embodiments, up to about 1% by weight, and in some embodiments, up to about 0.5% by weight.

[0073] E. Outer polymer coating If desired, an external polymer coating can also be applied to the anode disposed on the solid electrolyte. If used, the external polymer coating typically includes one or more layers formed from conductive polymer particles (e.g., formed from an extrinsic conductive polymer) as described above. The external coating can further penetrate into the edge regions of the capacitor body, increasing adhesion to the dielectric and providing a more mechanically robust part, thereby reducing equivalent series resistance and leakage current. Because 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 typically have larger dimensions than those used in the optional particles (e.g., in one or more outer layers) used in the solid electrolyte. For example, the ratio of the average size of the particles used in the external polymer coating to the average size of the particles used in the solid electrolyte is typically about 1.5 to about 30, in some embodiments about 2 to about 20, and in some embodiments about 5 to about 15. For example, the particles used in the outer coating may have an average size of from about 50 to about 800 nanometers, in some embodiments from about 80 to about 600 nanometers, and in some embodiments, from about 100 to about 500 nanometers.

[0074] A crosslinking agent can optionally be used in the outer polymer coating to further increase adhesion to the solid electrolyte. Typically, the crosslinking agent is applied before applying the dispersion used in the outer coating. Suitable crosslinking agents are described, for example, in U.S. Patent Publication No. 2007 / 0064376 to Merker et al., and include, for example, amines (e.g., diamines, triamines, oligomeric amines, polyamines, etc.); salts or compounds of polyvalent metal cations, such as Mg, Al, Ca, Fe, Cr, Mn, Ba, Ti, Co, Ni, Cu, Ru, Ce, or Zn; phosphonium compounds; sulfonium compounds; and the like. Particularly suitable examples include 1,4-diaminocyclohexane, 1,4-bis(aminomethyl)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.

[0075] The crosslinker is typically applied from a solution or dispersion, the pH of which, measured at 25°C, is 1 to 10, in some embodiments 2 to 7, and in some embodiments 3 to 6. An acidic compound can be used to help achieve the desired pH level. Examples of solvents or dispersants for the crosslinker include water or organic solvents, such as alcohols, ketones, carboxylic acid esters, and the like. The crosslinker can be applied to the capacitor body by any known process, such as spin coating, impregnation, casting, drop application, spray application, vapor deposition, sputtering, sublimation, knife coating, painting, or printing, e.g., inkjet, screen, or pad printing. Once applied, the crosslinker can be dried before applying the polymer dispersion. This process can then be repeated until the desired thickness is achieved. For example, the total thickness of the entire outer polymer coating, including the crosslinker and dispersion layers, can range from about 1 to about 50 μm, in some embodiments, from about 2 to about 40 μm, and in some embodiments, from about 5 to about 20 μm.

[0076] F. Cathode Coating If desired, the capacitor element can also employ a cathode coating disposed over the solid electrolyte and outer polymer coating. The cathode coating can include a metal particle layer comprising a multitude of conductive metal particles dispersed within a polymer matrix. The particles typically comprise from about 50% to about 99% by weight of the layer, in some embodiments from about 60% to about 98% by weight, and in some embodiments, from about 70% to about 95% by weight, while the polymer matrix typically comprises from about 1% to about 50% by weight, in some embodiments from about 2% to about 40% by weight, and in some embodiments, from about 5% to about 30% by weight of the layer.

[0077] The conductive metal particles can be formed from a variety of different metals, such as copper, nickel, silver, nickel, zinc, tin, lead, copper, aluminum, molybdenum, titanium, iron, zirconium, magnesium, and the like, as well as alloys thereof. Silver is a particularly suitable conductive metal for use in such layers. The metal particles often have relatively small dimensions, such as an average diameter of about 0.01 to about 50 micrometers, in some embodiments about 0.1 to about 40 micrometers, and in some embodiments about 1 to about 30 micrometers. While typically only one layer of metal particles is used, it should be understood that multiple layers can be used if desired. The total thickness of such one or more layers is in the range of about 1 μm to about 500 μm, in some embodiments about 5 μm to about 200 μm, and in some embodiments about 10 μm to about 100 μm.

[0078] The polymer matrix typically comprises a polymer, which may be thermoplastic or thermosetting in nature. However, the polymer is typically selected to contain a relatively small amount of polar groups so as to act as a barrier to silver ion electromigration and minimize the degree of water adsorption in the cathode coating. In this regard, the inventors have found that vinyl acetal polymers, such as polyvinyl butyral, polyvinyl formal, and the like, are particularly suitable for this purpose. For example, polyvinyl butyral can be formed by reacting polyvinyl alcohol with an aldehyde (e.g., butyraldehyde). Because this reaction is usually incomplete, polyvinyl butyral generally has a residual hydroxyl content. However, by minimizing this content, the polymer can have a lower degree of strongly polar groups, which would otherwise cause a high degree of moisture adsorption and lead to silver ion migration. For example, the residual hydroxyl content in polyvinyl acetal can be about 35 mol% or less, in some embodiments about 30 mol% or less, and in some embodiments, about 10 mol% to about 25 mol%. One commercially available example of such a polymer is available from Sekisui Chemical Co., Ltd. under the designation "BH-S" (polyvinyl butyral).

[0079] To form the cathode coating, a conductive paste is typically applied to the capacitor over the solid electrolyte, typically using one or more organic solvents in the paste. In general, a variety of different organic solvents can be used, such as 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); alcohols (e.g., benzyl alcohol, methanol, ethanol, n-propanol, iso-propanol, and butanol); triglycerides; ketones (e.g., acetone, methyl ethyl ketone, and methyl isobutyl ketone); esters (e.g., ethyl acetate, butyl acetate, diethylene glycol ether acetate, and methoxypropyl acetate); amides (e.g., dimethylformamide, dimethylacetamide, dimethylcapryl / capric 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 the like, as well as mixtures thereof. The organic solvent(s) typically comprise about 10% to about 70% by weight of the paste, in some embodiments about 20% to about 65% by weight, and in some embodiments about 30% to about 60% by weight. The metal particles typically comprise about 10% to about 60% by weight of the paste, in some embodiments about 20% to about 45% by weight, and in some embodiments about 25% to about 40% by weight. The resinous matrix typically comprises about 0.1% to about 20% by weight of the paste, in some embodiments about 0.2% to about 10% by weight, and in some embodiments about 0.5% to about 8% by weight.

[0080] The paste may have a relatively low viscosity, allowing it to be easily handled and applied to a capacitor element. The viscosity may range from about 50 to about 3,000 centipoise, in some embodiments from 100 to about 2,000 centipoise, and in some embodiments from about 200 to about 1,000 centipoise, as measured, for example, using a Brookfield DV-1 viscometer (cone-plate) operated at a speed of 10 rpm and a temperature of 25°C. If desired, thickeners or other viscosity modifiers can be used in the paste to increase or decrease the viscosity. Furthermore, the paste may be applied at a relatively thin thickness and still achieve the desired properties. For example, the paste thickness may be from about 0.01 to about 50 micrometers, in some embodiments from about 0.5 to about 30 micrometers, and in some embodiments, from about 1 to about 25 micrometers. Once applied, the metal paste may optionally be dried to remove some components, such as organic solvents. For example, drying can be carried out at a temperature of about 20°C to about 150°C, in some embodiments about 50°C to about 140°C, and in some embodiments about 80°C to about 130°C.

[0081] G. Other Components: Other layers known in the art can also be included in the capacitor if desired. For example, in some embodiments, a carbon layer (e.g., graphite) can be disposed between the solid electrolyte and the silver layer to help further limit contact between the silver layer and the solid electrolyte. Additionally, a precoat layer comprising an organometallic compound disposed over the dielectric can also be used.

[0082] II. Termination: Once formed, the capacitor element can be provided with terminations, particularly for use in surface mount applications. For example, a capacitor can include an anode termination to which the anode lead of the capacitor element is electrically connected, and a cathode termination to which the cathode of the capacitor element is electrically connected. Any conductive material can be used to form the terminations, such as conductive metals (e.g., copper, nickel, silver, nickel, zinc, tin, palladium, lead, copper, aluminum, molybdenum, titanium, iron, zirconium, magnesium, and alloys thereof). Particularly suitable 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 terminations is generally selected to minimize the thickness of the capacitor. For example, the thickness of the terminations can range from about 0.05 to about 1 millimeter, and 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 plate available from Wieland (Germany). If desired, the surfaces of the terminations can be electroplated with nickel, silver, gold, tin, etc., as is known in the art, to ensure that the final component can be mounted to a circuit board. In one particular embodiment, both surfaces of the terminations are plated with nickel and silver flash, respectively, while the mounting surface is also plated with a tin solder layer.

[0083] The terminations can be connected to the capacitor element using any technique known in the art. For example, in one embodiment, a lead frame can be provided that defines a cathode termination and an anode termination. To attach the electrolytic capacitor element to the lead frame, a conductive adhesive can first be applied to the surface of the cathode termination. The conductive adhesive can include, for example, conductive metal particles contained in a resin composition. The metal particles can be silver, copper, gold, platinum, nickel, zinc, bismuth, or the like. The resin composition can include a thermosetting resin (e.g., an epoxy resin), a hardener (e.g., an acid anhydride), and a coupling agent (e.g., a silane coupling agent). Suitable conductive adhesives are described in U.S. Patent Application Publication No. 2006 / 0038304 to Osako et al. The conductive adhesive can be applied to the cathode termination using any of a variety of techniques. For example, printing techniques can be used for their practical and cost-saving benefits. The anode lead can also be electrically connected to the anode termination using any technique known in the art, such as mechanical welding, laser welding, conductive adhesives, or the like. Once the anode lead is electrically connected to the anode termination, the conductive adhesive can then be cured to ensure proper adhesion of the electrolytic capacitor element to the cathode termination.

[0084] III. Housing The capacitor element can be incorporated into the housing in a variety of ways. For example, in some embodiments, the capacitor element can be housed in a case, which can then be filled with a resin material, such as a thermosetting resin (e.g., epoxy resin), that can be cured to form a hardened housing. The resin material can surround and encapsulate the capacitor element such that at least a portion of the anode and cathode terminations are exposed for mounting on a circuit board. When encapsulated in this manner, the capacitor element and resin material form an integral capacitor.

[0085] Of course, in other embodiments, it may be desirable to house the capacitor elements separately and in isolation within the housing. In this manner, the atmosphere of the housing can be selectively controlled to ensure it is dry, thereby limiting the amount of moisture that can contact the capacitor elements. For example, the moisture content of the air (expressed as relative humidity) may be about 10% or less, in some embodiments about 5% or less, in some embodiments about 3% or less, and in some embodiments, about 0.001 to about 1%. For example, the atmosphere may be gaseous and include at least one inert gas, such as nitrogen, helium, argon, xenon, neon, krypton, radon, and the like, as well as mixtures thereof. Typically, the inert gas constitutes the majority of the atmosphere within the housing, e.g., about 50% to 100% by weight, in some embodiments about 75% to 100% by weight, and in some embodiments about 90% to 99% by weight of the atmosphere. If desired, relatively small amounts of non-inert gases, such as carbon dioxide, oxygen, water vapor, and the like, may also be used. However, in such cases, the non-inert gas typically comprises no more than 15% by weight of the atmosphere within the housing, in some embodiments no more than 10% by weight, in some embodiments no more than about 5% by weight, in some embodiments no more than about 1% by weight, and in some embodiments, from about 0.01% to about 1% by weight.

[0086] Any of a variety of different materials can be used to form the housing, such as metal, plastic, ceramic, etc. For example, in one embodiment, the housing includes one or more layers of a metal such as tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, silver, steel (e.g., stainless steel), alloys thereof (e.g., conductive oxides), composites thereof (e.g., metal coated with a conductive oxide), etc. In other embodiments, the housing can include one or more layers of a ceramic material such as aluminum nitride, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, glass, etc., as well as combinations thereof.

[0087] The housing may have any desired shape, such as cylindrical, D-shaped, rectangular, triangular, prismatic, etc. For example, referring to FIG. 1 , one embodiment of a capacitor 100 is shown including a housing 122 and a capacitor element 120. In this particular embodiment, the housing 122 is generally rectangular. Typically, the housing and the capacitor element have the same or similar shapes to allow the capacitor element to be easily accommodated within the internal cavity. For example, in the embodiment shown, both the capacitor element 120 and the housing 122 have a generally rectangular shape.

[0088] If desired, the capacitors of the present invention can exhibit relatively high volumetric efficiency. To facilitate such high efficiency, the capacitor element typically occupies a substantial portion of the volume of the interior cavity of the housing. For example, the capacitor element can occupy at least about 30% by volume, at least about 50% by volume, at least about 60% by volume, at least about 70% by volume, at least about 80% by volume to about 98% by volume, and at least about 85% by volume to about 97% by volume of the interior cavity of the housing. To this end, the difference between the dimensions of the capacitor element and the dimensions of the interior cavity defined by the housing is typically relatively small.

[0089] For example, referring to FIG. 1 , capacitor element 120 may have a length (excluding the length of anode lead 6) that is relatively similar to the length of interior cavity 126 defined by housing 122. For example, the ratio of the length of the anode to the length of the interior cavity may range from about 0.40 to 1.00, in some embodiments from about 0.50 to about 0.99, in some embodiments from about 0.60 to about 0.99, and in some embodiments from about 0.70 to about 0.98. Capacitor element 120 may have a length of about 5 to about 10 millimeters, and interior cavity 126 may have a length of about 6 to about 15 millimeters. Similarly, the ratio of the height (in the z-direction) of capacitor element 120 to the height of interior cavity 126 may range from about 0.40 to 1.00, in some embodiments from about 0.50 to about 0.99, in some embodiments from about 0.60 to about 0.99, and in some embodiments from about 0.70 to about 0.98. The ratio of the width (in the x-direction) of capacitor element 120 to the width of internal cavity 126 may also range from about 0.50 to 1.00, in some embodiments from about 0.60 to about 0.99, in some embodiments from about 0.70 to about 0.99, in some embodiments from about 0.80 to about 0.98, and in some embodiments from about 0.85 to about 0.95. For example, the width of capacitor element 120 may be from about 2 to about 7 millimeters, the width of internal cavity 126 may be from about 3 to about 10 millimeters, the height of capacitor element 120 may be from about 0.5 to about 2 millimeters, and the width of internal cavity 126 may be from about 0.7 to about 6 millimeters.

[0090] Although by no means required, the capacitor element can be attached to the housing such that anode and cathode terminations are formed on the exterior of the housing for subsequent incorporation into a circuit. The specific configuration of the terminations can be determined depending on the intended application. For example, in one embodiment, the capacitor can be formed to be surface-mountable and yet mechanically robust. For example, the anode lead can be electrically connected to external surface-mountable anode and cathode terminations (e.g., pads, sheets, plates, frames, etc.). Such terminations can extend through the housing to connect to the capacitor. The thickness or height of the terminations is generally selected to minimize the thickness of the capacitor. For example, the thickness of the terminations can range from about 0.05 to about 1 millimeter, and in some embodiments, from about 0.05 to about 0.5 millimeters, and from about 0.1 to about 0.2 millimeters. If desired, the surfaces of the terminations can be electroplated with nickel, silver, gold, tin, etc., as known in the art, to ensure that the final component is mountable to a circuit board. In one particular embodiment, one or more terminations are each deposited with a nickel and silver flash, and the mounting surface is also plated with a tin solder layer. In another embodiment, one or more terminations have a thin outer metal layer (e.g., gold) deposited on a base metal layer (e.g., copper alloy) to further increase electrical conductivity.

[0091] In some embodiments, a connecting member can be used within the housing's internal cavity to facilitate connection to the terminations in a mechanically stable configuration. For example, referring again to FIG. 1 , capacitor 100 can include connecting member 162 formed from a first portion 167 and a second portion 165. Connecting member 162 can be formed from the same conductive material as the external terminations. First portion 167 and second portion 165 can be integral or can be separate pieces connected either directly or via an additional conductive member (e.g., metal). In the illustrated embodiment, second portion 165 is oriented in a plane generally parallel to the lateral direction (e.g., y-direction) in which leads 6 extend. First portion 167 is "upright" in the sense that it is oriented in a plane generally perpendicular to the lateral direction in which leads 6 extend. In this manner, first portion 167 can limit horizontal movement of leads 6, increasing surface contact and mechanical stability during use. If desired, insulating material 7 (e.g., Teflon™ washers) can be used around leads 6.

[0092] First portion 167 may have a mounting region (not shown) that connects to anode lead 6. Such region may have a "U-shape" to further increase surface contact and mechanical stability of lead 6. Connection of such region to lead 6 may be achieved using any of a variety of known techniques, such as welding, laser welding, conductive adhesives, etc. For example, in one particular embodiment, this region is laser welded to anode lead 6. However, regardless of the technique selected, first portion 167 may hold anode lead 6 in a substantially horizontal orientation, further increasing the dimensional stability of capacitor 100.

[0093] Referring again to FIG. 1 , one embodiment of the present invention is shown in which connection member 162 and capacitor element 120 are connected to housing 122 through anode and cathode terminations (127 and 129, respectively). More specifically, housing 122 in this embodiment includes an outer wall 123 and two opposing side walls 124, forming a cavity 126 therebetween that accommodates capacitor element 120. Outer wall 123 and side walls 124 may be formed from one or more layers of metal, plastic, or ceramic material, as described above. In this particular embodiment, anode termination 127 includes a first region 127a disposed within housing 122 and electrically connected to connection member 162, and a second region 127b disposed outside housing 122 and providing mounting surface 201. Additionally, cathode termination 129 includes a first region 129a disposed within housing 122 and electrically connected to the solid electrolyte of capacitor element 120, and a second region 129b disposed outside housing 122 and providing mounting surface 203. It should be understood that portions of such regions need not be entirely disposed within or outside the housing.

[0094] In the illustrated embodiment, conductive trace 127c extends within housing outer wall 123, connecting first region 127a and second region 127b. Similarly, conductive trace 129c extends within housing outer wall 123, connecting first region 127a and second region 127b. The conductive traces and / or termination regions may be separate or integral. In addition to extending through the housing outer wall, the traces may be located elsewhere, such as outside the outer wall. Of course, the present invention is in no way limited to using conductive traces to form the desired terminations.

[0095] Regardless of the particular configuration used, the connection of terminations 127 and 129 to capacitor element 120 can be made using any known technique, such as welding, laser welding, conductive adhesives, etc. For example, in one particular embodiment, conductive adhesive 131 is used to connect second portion 165 of connecting member 162 to anode termination 127. Additionally, conductive adhesive 133 is used to connect the cathode of capacitor element 120 to cathode termination 129.

[0096] In some cases, a polymeric constraining member may be disposed in contact with one or more surfaces of the capacitor element, such as the rear surface, front surface, top surface, bottom surface, one or more side surfaces, or any combination thereof. The polymeric constraining member may reduce the likelihood of delamination of the capacitor element from the housing. In this regard, the polymeric constraining member may have a degree of strength that enables it to hold the capacitor element in a relatively fixed position even when subjected to vibrational forces, but is not so tough that it cracks. For example, the constraining member may have a tensile strength, measured at a temperature of about 25°C, of ​​about 1 to about 150 megapascals (MPa), in some embodiments, about 2 to about 100 MPa, in some embodiments, about 10 to about 80 MPa, and in some embodiments, about 20 to about 70 MPa. It is typically desirable that the constraining member not be electrically conductive. For example, referring again to FIG. 1, one embodiment is shown in which a single polymeric constraining member 197 is disposed in contact with the top surface 181 and the rear surface 177 of the capacitor element 120. While a single constraining member is shown in FIG. 1, it should be understood that multiple separate constraining members can be used to achieve the same function. Indeed, more generally, any number of polymeric constraining members can be used to contact any desired surface of the capacitor element. When multiple constraining members are used, they can be in contact with each other or can be physically separated. For example, in one embodiment, a second polymeric constraining member (not shown) can be used to contact the top surface 181 and front surface 179 of the capacitor element 120. The first polymeric constraining member 197 and the second polymeric constraining member (not shown) can either be in contact with each other or not. In yet other embodiments, the polymeric constraining member can also contact the bottom surface 183 and / or one or more side surfaces of the capacitor element 120, in addition to or instead of other surfaces.

[0097] Regardless of how it is applied, it is typically desirable for the polymeric constraining member also to contact at least one surface of the housing to help further mechanically stabilize the capacitor element against potential delamination. For example, the constraining member can contact the interior surface of one or more side walls, outer wall, lid, etc. For example, in FIG. 1 , polymeric constraining member 197 contacts interior surface 107 of side wall 124 and interior surface 109 of outer wall 123. While in contact with the housing, it is desirable for at least a portion of the cavity defined by the housing to remain unoccupied to allow inert gas to flow through the cavity and limit contact of the solid electrolyte with oxygen. For example, at least about 5% of the cavity volume, and in some embodiments, about 10% to about 50% of the cavity volume, typically remains unoccupied by the capacitor element and polymeric constraining member.

[0098] Once connected in the desired configuration, the resulting package is hermetically sealed as described above. For example, referring again to FIG. 1 , the housing 122 can also include a lid 125 that is disposed on top of the sidewall 124 after the capacitor element 120 and polymeric constraining member 197 are disposed within the housing 122. The lid 125 can be formed from ceramic, metal (e.g., iron, copper, nickel, cobalt, etc., and alloys thereof), plastic, etc. If desired, a sealing member 187 can be disposed between the lid 125 and the sidewall 124 to help provide a good seal. For example, in one embodiment, the sealing member can include a glass-to-metal sealant, a Kovar® ring (Goodfellow Cambridge, Ltd.), etc. The height of the sidewall 124 is generally such that the lid 125 does not contact any surface of the capacitor element 120 to prevent contamination of the capacitor element. The polymeric constraining member 197 may or may not be in contact with the lid 125. Once in the desired location, the lid 125 is hermetically sealed to the sidewall 124 using known techniques such as welding (e.g., resistance welding, laser welding, etc.), soldering, etc. The hermetic sealing is typically performed in the presence of an inert gas, such as those described above, so that the resulting assembly is substantially free of reactive gases such as oxygen or water vapor.

[0099] It should be understood that the described embodiment is merely exemplary, and that various other configurations for hermetically sealing the capacitor element within the housing can be used in the present invention. For example, referring to FIG. 2 , another embodiment of a capacitor 200 is shown using a housing 222 including an outer wall 123 and a lid 225, forming a cavity 126 therebetween that accommodates the capacitor element 120 and the polymeric restraining member 197. The lid 225 includes an outer wall 223 integral with at least one side wall 224. For example, in the embodiment shown, two opposing side walls 224 are shown in cross section. The outer walls 223 and 123 both extend in a lateral direction (y-direction) and are generally parallel to each other and to the lateral direction of the anode lead 6. The side wall 224 extends from the outer wall 223 in a longitudinal direction that is generally perpendicular to the outer wall 223. The distal end 500 of the lid 225 is defined by the outer wall 223 and the proximal end 501 is defined by the lip 253 of the side wall 224 .

[0100] The lip 253 extends laterally from the sidewall 224, which may be generally parallel to the lateral direction of the outer wall 123. The angle between the sidewall 224 and the lip 253 may vary, but is typically between about 60° and about 120°, in some embodiments, between about 70° and about 110°, and in some embodiments, between about 80° and about 100° (e.g., about 90°). The lip 253 also defines a peripheral edge 251, which may be generally perpendicular to the lateral direction in which the lip 253 and the outer wall 123 extend. The peripheral edge 251 is located beyond the perimeter of the sidewall 224 and may be generally flush with the edge 151 of the outer wall 123. The lip 253 may be sealed to the outer wall 123 using any known technique, such as welding (e.g., resistance or laser), soldering, adhesives, etc. For example, in the embodiment shown, a sealing member 287 (glass-to-metal seal, Kovar® ring, etc.) is used between the components to facilitate bonding therebetween. In any event, the use of such a lip can allow for a more stable connection between the components, improving the sealing and mechanical stability of the capacitor.

[0101] Still other possible housing structures can be used in the present invention. For example, FIG. 3 shows a capacitor 300 having a housing structure similar to that of FIG. 2, except that terminal pins 327b and 329b are used as external terminations for the anode and cathode, respectively. More specifically, terminal pin 327a extends through a trace 327c formed in outer wall 323 and is connected to anode lead 6 using known techniques (e.g., welding). An additional section 327a can be used to secure pin 327b. Furthermore, terminal pin 329b extends through a trace 329c formed in outer wall 323 and is connected to the cathode by the conductive adhesive 133 described above.

[0102] The embodiments shown in FIGS. 1-3 are discussed herein with respect to only a single capacitor element. However, it should be understood that multiple capacitor elements can also be hermetically sealed within a housing. Multiple capacitor elements can be attached to the housing using any of a variety of different techniques. For example, referring to FIG. 4, one particular embodiment of a capacitor 400 including two capacitor elements is shown and will now be described in more detail. More specifically, capacitor 400 includes a first capacitor element 420a in electrical communication with a second capacitor element 420b. In this embodiment, the capacitor elements are arranged with their major surfaces in a horizontal configuration. That is, the major surface of capacitor element 420a, defined by its width (x-direction) and length (y-direction), is disposed adjacent to the corresponding major surface of capacitor element 420b. Thus, these major surfaces are generally coplanar. Alternatively, the capacitor elements can be arranged with their major surfaces not coplanar but perpendicular to each other in a direction, such as the z-direction or the x-direction. Of course, the capacitor elements need not extend in the same direction.

[0103] Capacitor elements 420a and 420b are disposed within a housing 422 that includes an outer wall 423 and side walls 424 and 425 that together define a cavity 426. Although not shown, a lid can be used to cover the top surfaces of side walls 424 and 425 and seal assembly 400 as described above. In some cases, polymer restraining members can be used to help limit vibration of the capacitor elements. For example, in FIG. 4, separate polymer restraining members 497a and 497b are positioned adjacent to and in contact with capacitor elements 420a and 420b, respectively. Polymer restraining members 497a and 497b can be positioned in a variety of different locations. Furthermore, one of the restraining members can be eliminated, or additional restraining members can be used. For example, in some embodiments, it may be desirable to use polymer restraining members between capacitor elements to further improve mechanical stability.

[0104] In addition to the capacitor elements, the capacitor also includes an anode termination to which the anode lead of each capacitor element is electrically connected, and a cathode termination to which the cathode of each capacitor element is electrically connected. For example, referring again to FIG. 4 , multiple capacitor elements are shown connected in parallel to a common cathode termination 429. In this particular embodiment, the cathode termination 429 is initially provided in a plane generally parallel to the bottom surface of the capacitor element and may be in electrical contact with a conductive trace (not shown). The capacitor 400 also includes connection members 427 and 527 connected to the anode leads (407a and 407b, respectively) of capacitor elements 420a and 420b. More specifically, the connection member 427 includes an upstanding portion 465 and a planar portion 463 connected to the anode termination (not shown). Furthermore, the connection member 527 includes an upstanding portion 565 and a planar portion 563 connected to the anode termination (not shown). Of course, it should be understood that a wide variety of other types of connection mechanisms may be used. The claims as filed are as follows: [Claim 1] an anode body containing tantalum; a dielectric disposed over the anode body; and a solid electrolyte disposed on the dielectric; 1. A solid electrolytic capacitor comprising a capacitor element comprising: said solid electrolyte comprising an intrinsically conductive polymer comprising repeating thiophene units; and End and the capacitor exhibits a charge / discharge capacitance after being subjected to a surge voltage of 3,000 cycles and an initial capacitance before being subjected to the surge voltage, wherein the ratio of the charge / discharge capacitance to the initial capacitance is about 0.75 to 1. [Claim 2] The intrinsically conductive polymer has the following formula (I): [ka] (In the formula, R is (CH2) a -O-(CH2) b -L (wherein L is a bond or HC([CH] c H) is) is; a is 0 to 10; b is 1 to 18; c is 0 to 10; M is an anion; X is a cation 2. The solid electrolytic capacitor of claim 1, comprising a repeating thiophene unit of: [Claim 3] The intrinsically conductive polymer has the following general formula (III): [ka] (In the formula, a is 0 to 10; b is 1 to 18; R5 is an optionally substituted C1-C6 linear or branched alkyl group or a halogen atom; X is a hydrogen atom, an alkali metal, or NH(R 1 )3(wherein, R 1are each independently a hydrogen atom or an optionally substituted C1-C6 alkyl group, or HNC5H5) 10. The solid electrolytic capacitor of claim 1, comprising a repeating thiophene unit having the formula: [Claim 4] 4. The solid electrolytic capacitor according to claim 3, wherein a is 1 and b is 3 or 4. [Claim 5] 4. The solid electrolytic capacitor of claim 3, wherein R5 is methyl. [Claim 6] 4. The solid electrolytic capacitor according to claim 3, wherein X is an alkali metal. [Claim 7] The thiophene repeating unit is selected from the group consisting of sodium 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 ...methyl-1-propanesulfonate, sodium 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]diox Sodium thieno[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-hexyl-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-fluoro-1-propanesulfonate Sodium 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]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate,4]triethylammonium dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, or a combination thereof. [Claim 8] The polymer has a viscosity of about 20 S / cm End 2. The solid electrolytic capacitor according to claim 1, having a specific conductivity of [Claim 9] 10. The solid electrolytic capacitor of claim 1, wherein the solid electrolyte comprises at least one inner layer comprising the inherently conductive polymer. [Claim 10] 10. The solid electrolytic capacitor of claim 9, wherein the inner layer is generally free of extrinsic conductive polymers. [Claim 11] 10. The solid electrolytic capacitor of claim 1, wherein the solid electrolyte comprises at least an outer layer. [Claim 12] 12. The solid electrolytic capacitor of claim 11, wherein the outer layer is formed from particles comprising a polymeric counterion and an extrinsic conductive polymer. [Claim 13] 10. The solid electrolytic capacitor of claim 1, further comprising a precoat formed from an organometallic compound disposed on the anode body. [Claim 14] The organometallic compound is represented by the following general formula (II): [ka] (In the formula, R1, R2, and R3 are independently alkyl, alkenyl, aryl, heteroaryl, cycloalkyl, heterocyclyl, halo, haloalkyl, or hydroxyalkyl; R4 and R5 are independently hydrogen, alkyl, independently alkyl, alkenyl, aryl, heteroaryl, cycloalkyl, heterocyclyl, halo, haloalkyl, hydroxyalkyl, or N, R4 and R5 together with one or more additional atoms form a ring structure; Z is an organic group. 14. The solid electrolytic capacitor of claim 13, wherein the monoaminofunctional silane has the formula: [Claim 15] 15. The solid electrolytic capacitor of claim 14, wherein the monoaminofunctional silane is a primary amine. [Claim 16] 16. The solid electrolytic capacitor of claim 15, wherein the primary amine is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3-aminopropyltris(methoxyethoxy)silane, 11-aminoundecyltriethoxysilane, 2(4-pyridylethyl)triethoxysilane, 2-(trimethoxysilylethyl)pyridine, N-(3-trimethoxysilylpropyl)pyrrole, 3-(m-aminophenoxypropyltrimethoxysilane, aminopropylsilanetriol, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyldimethylethoxysilane, or a combination thereof. [Claim 17] 15. The solid electrolytic capacitor of claim 14, wherein the monoaminofunctional silane is a secondary amine. [Claim 18] The secondary amine is selected from the group consisting of N-butylaminopropyltrimethoxysilane, N-ethylaminoisobutyltrimethoxysilane, n-methylaminopropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, 3-(N-allylamino)propyltrimethoxysilane, cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminopropyltrimethoxysilane, N-ethylaminoisobutylmethyldiethoxysilane, (phenylaminoethyl)methyl-diethoxysilane, and N-phenylaminomethytrimethoxysilane. e), N-methylaminopropylmethyl-dimethoxysilane, or a combination thereof. [Claim 19] The organometallic compound is represented by the following general formula (III): [ka] (In the formula, R1, R2, and R3 are independently alkyl, alkenyl, aryl, heteroaryl, cycloalkyl, heterocyclyl, halo, haloalkyl, or hydroxyalkyl; R4 and R5 are independently hydrogen, alkyl, independently alkyl, alkenyl, aryl, heteroaryl, cycloalkyl, heterocyclyl, halo, haloalkyl, hydroxyalkyl, or N, R4 and R5 together with one or more additional atoms form a ring structure; Z1 and Z2 are independently an organic group. 14. The solid electrolytic capacitor of claim 13, wherein the diamino-functional silane has the formula: [Claim 20] 20. The solid electrolytic capacitor of claim 19, wherein the diamino-functional silane is N-(2-aminoethyl)-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(6-aminohexyl)aminomethyltriethoxysilane, N-(6-aminohexyl)aminopropyltrimethoxysilane, N-(2-aminoethyl)-11-aminoundecyltrimethoxysilane, (aminoethylaminomethyl)-phenethyltrimethoxysilane, N-3-[(amino(polypropyleneoxy)]-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylsilanetriol, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, (aminoethylamino)-3-isobutyldimethylmethoxysilane, or a combination thereof. [Claim 21] 10. The solid electrolytic capacitor of claim 1, further comprising an outer polymer coating disposed over the solid electrolyte, the outer polymer coating comprising conductive polymer particles. [Claim 22] 22. The solid electrolytic capacitor of claim 21, wherein the outer polymer coating further comprises a cross-linking agent. [Claim 23] 2. The solid electrolytic capacitor according to claim 1, wherein the anode body is a sintered pellet. [Claim 24] 10. The solid electrolytic capacitor of claim 1, further comprising a housing in which the capacitor element is housed. [Claim 25] 10. The solid electrolyte capacitor of claim 1, wherein the capacitor element further comprises a cathode coating including a metal particle layer disposed on the solid electrolyte, the metal particle layer including a plurality of conductive metal particles. yapashta. [Claim 26] Approximately 55 volts End 10. The solid electrolytic capacitor of claim 1, wherein the solid electrolytic capacitor exhibits a breakdown voltage of [Claim 27] The dielectric has a thickness of about 60 nanometers End 10. The solid electrolytic capacitor of claim 1, having a thickness of [Example]

[0105] The present invention may be better understood with reference to the following examples.

[0106] Test Procedure capacitance Capacitance was measured using a Keithley 3330 precision LCZ meter with Kelvin leads, using a DC bias of 2.2 volts and a 0.5 volt peak-to-peak sine wave signal. The operating frequency was 120 Hz and the temperature was 23°C ± 2°C.

[0107] Breakdown Voltage Breakdown voltage was measured using a Keithley 2400 SourceMeter at a temperature of 23° C.±2° C. Individual capacitors were measured using the formula: Current (A) = Nominal Capacitance (F) x dU / dt (where dU / dt represents the voltage gradient, which is usually set to 10 V / s) The voltage is measured during charging, and when the applied voltage decreases by more than 10%, the maximum achieved voltage value is recorded as the breakdown voltage.

[0108] Equivalent series resistance (ESR) The equivalent series resistance can be measured using a Keithley 3330 precision LCZ meter with Kelvin leads, using a DC bias of 2.2 volts and a sine wave signal of 0.5 volts peak-to-peak. The operating frequency was 100 kHz and the temperature was 23°C ± 2°C.

[0109] Dielectric tangent The dissipation factor can be measured using a Keithley 3330 precision LCZ meter with Kelvin leads, using a DC bias of 2.2 volts and a sine wave signal of 0.5 volts peak-to-peak. The operating frequency can be 120 Hz and the temperature can be 23°C ± 2°C. Leakage Current The leakage current may be measured using a leakage tester at a temperature of 23°C ± 2°C and rated voltage after a minimum of 60 seconds.

[0110] Surge Voltage Test Surge voltage testing (10-25 parts) can be performed at a temperature of 85°C ± 3°C and a voltage equal to 1.3 times the rated voltage (e.g., 45.5V). The resistance used in the test circuit can be 33 ohms. Each cycle consists of a 30-second surge voltage application followed by a 30-second discharge period. Test specimens are dried at 125°C for at least 12 hours before testing. Capacitance can be measured every 1,000 pulse cycles up to 3,000 or 5,000 pulses after a recovery period.

[0111] Dielectric Thickness Dielectric thickness can be measured using a Zeiss Sigma FESEM at magnifications of 20,000x to 50,000x. Samples can be prepared by cutting the finished part through a plane perpendicular to its longest dimension. Thickness measurements can be taken at the perpendicular cut through the dielectric layer.

[0112] Example 1 Anode samples were prepared using 40,000 μFV / g tantalum powder. Each anode sample was embedded with a tantalum wire, with a density of 5.3 g / cm. 3The pellets were pressed to a density of 1000 psi and sintered at 1380°C. The resulting pellets had dimensions of 5.60 x 3.65 x 0.72 mm. The pellets were anodized to 76.0 volts in a water / phosphoric acid electrolyte with a conductivity of 8.6 mS at a temperature of 40°C to form a dielectric layer. The pellets were anodized again to 130 volts for 10 seconds in a water / boric acid / disodium tetraborate electrolyte with a conductivity of 2.0 mS at a temperature of 30°C to form a thicker oxide layer deposited on the exterior. Once anodized, four precoat layers of an organometallic compound were applied, including a solution (1.0%) of (3-aminopropyl)trimethoxysilane in ethanol. A conductive polymer coating was formed by immersing the anode in a solution of poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butane-sulfonic acid). Once coated, the part was dried at 125 °C for 15 minutes. This process was repeated twice. The part was then immersed in a dispersed poly(3,4-ethylenedioxythiophene) (Clevios™ K, Heraeus) with a solids content of 1.1% and a viscosity of 20 mPa·s. Once coated, the part was dried at 125 °C for 15 minutes. This process was repeated eight times. The part was then immersed in a dispersed poly(3,4-ethylenedioxythiophene) with a solids content of 2.0% and a viscosity of 20 mPa·s. The parts were then immersed in a poly(3,4-ethylenedioxythiophene) dispersion with a solids content of 2% and a viscosity of 160 mPa·s (Clevios™ K, Heraeus). Once coated, the parts were dried at 125°C for 15 minutes. This process was repeated three times. The parts were then immersed in a poly(3,4-ethylenedioxythiophene) dispersion with a solids content of 2% and a viscosity of 160 mPa·s (Clevios™ K, Heraeus). Once coated, the parts were dried at 125°C for 15 minutes. This process was repeated 14 times. Next, the parts were immersed in a graphite dispersion and dried. Finally, the parts were immersed in a silver dispersion and dried. A large number of parts (450) of 47 μF / 35 V capacitors were fabricated in this way and encapsulated in silica resin.

[0113] Example 2 Capacitors were formed as described in Example 1, except that a different conductive polymer coating was used. Specifically, the conductive polymer coating was formed by immersing the anode in a solution of poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butane-sulfonic acid). Once coated, the part was dried at 125°C for 15 minutes. This process was repeated eight times. The part was then immersed in a dispersed poly(3,4-ethylenedioxythiophene) (Clevios™ K, Heraeus) with a 2.0% solids content and a viscosity of 20 mPa·s. Once coated, the part was dried at 125°C for 15 minutes. This process was repeated three times. The anode was immersed in an organic solution of polyaniline with a dopant, followed by drying at 150°C for 30 minutes. A conductive polymer coating was formed by coating the entire composition. The entire composition was then immersed in a solution containing sulfonic acid and then dried at 150°C for 30 minutes. This process was repeated three times. The parts were then immersed in a dispersion of poly(3,4-ethylenedioxythiophene) with a solids content of 2% and a viscosity of 160 mPa·s (Clevios™ K. Heraeus). Once coated, the parts were dried at 125°C for 15 minutes. This process was repeated 14 times. Next, the parts were immersed in a graphite dispersion and dried. Finally, the parts were immersed in a silver dispersion and dried. A large number of 47 μF / 35 V capacitor parts (450) were fabricated in this way and encapsulated in silica resin.

[0114] Example 3 Anode samples were prepared using 40,000 μFV / g tantalum powder. Each anode sample was embedded with a tantalum wire, with a density of 5.3 g / cm. 3The pellets were pressed to a density of 1000 psi and sintered at 1410°C. The resulting pellets had dimensions of 5.60 x 3.65 x 0.80 mm. The pellets were anodized to 76.0 volts in a water / phosphoric acid electrolyte with a conductivity of 8.6 mS at a temperature of 40°C to form a dielectric layer. The pellets were anodized again to 150 volts for 5 seconds in a water / boric acid / disodium tetraborate electrolyte with a conductivity of 2.0 mS at a temperature of 30°C to form a thicker oxide layer deposited on the outside. Once anodized, four precoat layers of an organometallic compound were used, including a solution (1.0%) of (3-aminopropyl)trimethoxysilane in ethanol. The poly( 3 -(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy) -1-methyl-1-propane A conductive polymer coating was formed by immersing the anode in a solution of α-sulfonic acid. Once coated, the part was dried at 125°C for 15 minutes. This process was repeated twice. The part was then immersed in a dispersion of poly(3,4-ethylenedioxythiophene) (Clevios™ K, Heraeus) with a solids content of 1.1% and a viscosity of 20 mPa·s. Once coated, the part was dried at 125°C for 15 minutes. This process was repeated eight times. The part was then immersed in a dispersion of poly(3,4-ethylenedioxythiophene) (Clevios™ K, Heraeus) with a solids content of 2.0% and a viscosity of 20 mPa·s. Once coated, the part was dried at 125°C for 15 minutes. This process was repeated three times. The parts were then immersed in a dispersion of poly(3,4-ethylenedioxythiophene) (Clevios™ K, Heraeus) with a solids content of 2% and a viscosity of 160 mPa·s. Once coated, the parts were dried at 125°C for 15 minutes. This process was repeated 14 times. Next, the parts were immersed in a graphite dispersion and allowed to dry. Finally, the parts were immersed in a silver dispersion and allowed to dry. A large number of parts (450) of 47 μF / 35 V capacitors were fabricated in this way and encapsulated in silica resin.

[0115] Example 4 The capacitor was fabricated in the manner described in Example 3, except that a different conductive polymer coating was used. That is, poly( 3 -(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy) -1-methyl-1-propane A conductive polymer coating was formed by immersing the anode in a solution of α-sulfonic acid. Once coated, the part was dried at 125°C for 15 minutes. This process was repeated six times. The part was then immersed in a dispersion of poly(3,4-ethylenedioxythiophene) (Clevios™ K, Heraeus) with a 2.0% solids content and a viscosity of 20 mPa·s. Once coated, the part was dried at 125°C for 15 minutes. This process was repeated three times. The part was then immersed in a dispersion of poly(3,4-ethylenedioxythiophene) (Clevios™ K, Heraeus) with a 2% solids content and a viscosity of 160 mPa·s. Once coated, the part was dried at 125°C for 15 minutes. This process was repeated 14 times. Next, the part was immersed in a graphite dispersion and allowed to dry. Finally, the part was immersed in a silver dispersion and allowed to dry. In this way, a large number of 47 μF / 35 V capacitor components (450) were fabricated and encapsulated in silica resin.

[0116] The minimum, average and maximum measured BDV values, as well as the average dielectric thickness, are shown in Table 1 below.

[0117] [Table 1] The median capacitance results within the surge voltage test are shown in Table 2 below.

[0118] [Table 2] These and other modifications and variations of the present invention may be practiced by those skilled in the art without departing from the spirit and scope of the present invention. Moreover, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those skilled in the art will recognize that the above description is by way of example only and is not intended to limit the invention as further described in the appended claims.

Claims

1. A solid electrolytic capacitor including a capacitor element, the capacitor element comprising: an anode body comprising tantalum; a dielectric disposed on the anode body; a precoat disposed on the anode body, the precoat being formed from a monoaminofunctional silane that is a primary amine; A solid electrolyte, at least one inner layer disposed over the precoat, the inner layer being generally free of extrinsic conductive polymers and including an intrinsically conductive polymer comprising repeating thiophene units, the intrinsically conductive polymer having a specific conductivity of about 20 S / cm or greater; at least one outer layer disposed over the inner layer and comprising conductive polymer particles comprising a complex of an exogenous conductive thiophene polymer and a counterion; the solid electrolyte comprising: an outer polymer coating disposed over the solid electrolyte, the outer polymer coating comprising conductive polymer particles comprising a complex of an exogenous conductive thiophene polymer and a counterion; Including, The solid electrolytic capacitor, wherein the capacitor exhibits a dielectric strength of about 0.6 volts / nanometer or greater, and further wherein the capacitor exhibits a charge / discharge capacitance after being subjected to 3,000 cycles of a surge voltage and an initial capacitance before being subjected to the surge voltage, wherein the ratio of the charge / discharge capacitance to the initial capacitance is about 0.75 to 1.

2. The intrinsically conductive polymer has the following formula (I): 【Chemical 1】 (In the formula, R is (CH ２ ) ａ -O-(CH ２ ) ｂ -L (wherein L is a bond or HC([CH ２ ] ｃ H) is); a is 0 to 10; b is 1 to 18; c is 0 to 10; M is an anion; X is a cation.

2. The solid electrolytic capacitor of claim 1, comprising repeating thiophene units of the formula:

3. The intrinsically conductive polymer has the following general formula (III): 【Chemistry 2】 (In the formula, a is 0 to 10; b is 1 to 18; R ５ is an optionally substituted C １ ~C ６ a linear or branched alkyl group or a halogen atom; X is a hydrogen atom, an alkali metal, NH(R １ ) ３ (In the formula, R １ are each independently C, which is a hydrogen atom or is optionally substituted １ ~C ６ alkyl group), or HNC ５ H ５ is) 10. The solid electrolytic capacitor of claim 1, comprising repeating thiophene units having the formula:

4. 4. The solid electrolytic capacitor according to claim 3, wherein a is 1 and b is 3 or 4.

5. R ５ The solid electrolytic capacitor according to claim 3 , wherein is methyl.

6. 4. The solid electrolytic capacitor of claim 3, wherein X is an alkali metal.

7. The thiophene repeating unit is preferably sodium 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-propyl-1-propanesulfonate, sodium 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-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 ... sodium thieno[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-hexyl-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-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-fluoro-1-propanesulfonate Sodium 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]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate triethylammonium, or a combination thereof.

8. 2. The solid electrolytic capacitor of claim 1, wherein the primary amine is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3-aminopropyltris(methoxyethoxy)silane, 11-aminoundecyltriethoxysilane, 2(4-pyridylethyl)triethoxysilane, 2-(trimethoxysilylethyl)pyridine, N-(3-trimethoxysilylpropyl)pyrrole, 3-(m-aminophenoxypropyltrimethoxysilane, aminopropylsilanetriol, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyldimethylethoxysilane, or a combination thereof.

9. The solid electrolytic capacitor of claim 1 , wherein the outer polymer coating further comprises a cross-linking agent.

10. The solid electrolytic capacitor according to claim 1 , wherein the anode body is a sintered pellet.

11. The solid electrolytic capacitor of claim 1 further comprising a housing in which the capacitor element is contained.

12. 10. The solid electrolytic capacitor of claim 1, wherein the capacitor element further comprises a cathode coating comprising a metal particle layer disposed on the solid electrolyte, the metal particle layer comprising a plurality of conductive metal particles.

13. 10. The solid electrolytic capacitor of claim 1, exhibiting a breakdown voltage of about 55 volts or greater.

14. 10. The solid electrolytic capacitor of claim 1, wherein the dielectric has a thickness of about 60 nanometers or greater.

15. 2. The solid electrolytic capacitor of claim 1, wherein the capacitor exhibits a charge / discharge capacitance after being subjected to 5,000 cycles of a surge voltage and an initial capacitance before being subjected to the surge voltage for 5,000 cycles, and the ratio of the charge / discharge capacitance to the initial capacitance is about 0.9 to 1.

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