Nonionic surfactant in electrolytic capacitor solid electrolyte

Solid electrolytic capacitors (eg, tantalum capacitors) typically press a metal powder (eg, tantalum) around a metal lead wire, sinter the press, anodize the sintered anode, and then solid. It is made by adding an electrolyte. Intrinsically conductive polymers are often used as solid electrolytes due to these advantageous low equivalent series resistance ("ESR") and "flame retardant / non-flammable" failure modes. In recent years, conductive polymer slurries containing a composite of poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid ("PEDET: PSS complex") are subject to high-speed switch-on or operating current spikes. It is used as a solid electrolyte material due to their ability to handle high voltages. Although some benefits have been achieved, one problem with polymer slurry-based capacitors is that these capacitances are highly temperature dependent. For example, capacitance tends to decrease significantly at low temperatures (eg, -55 ° C), which is the use of such capacitors in cold temperature environments often encountered in aerospace or military applications. May interfere with. Another problem with polymer slurry-based capacitors is that they can only achieve relatively low percentages of these wet capacitances, which means they have relatively large capacitances in the presence of atmospheric humidity. Means having a loss and / or fluctuation.

<p num="0002"><patcit num="1"><text>U.S. Pat. No. 6,322,912</text></patcit><patcit num="2"><text>U.S. Pat. No. 6,391,275</text></patcit><patcit num="3"><text>U.S. Pat. No. 6,416,730</text></patcit><patcit num="4"><text>U.S. Pat. No. 6,527,937</text></patcit><patcit num="5"><text>U.S. Pat. No. 6,576,099</text></patcit><patcit num="6"><text>U.S. Pat. No. 6,592,740</text></patcit><patcit num="7"><text>U.S. Pat. No. 6,639,787</text></patcit><patcit num="8"><text>U.S. Pat. No. 7,220,397</text></patcit><patcit num="9"><text>U.S. Patent Application Publication No. 2005/0019581</text></patcit><patcit num="10"><text>U.S. Patent Application Publication No. 2005/0103638</text></patcit><patcit num="11"><text>U.S. Patent Application Publication No. 2005/0013765</text></patcit><patcit num="12"><text>U.S. Pat. No. 6,197,252</text></patcit><patcit num="13"><text>U.S. Pat. No. 6,987,663</text></patcit><patcit num="14"><text>U.S. Pat. No. 5,111,327</text></patcit><patcit num="15"><text>U.S. Pat. No. 6,635,729</text></patcit><patcit num="16"><text>U.S. Pat. No. 7,515,396</text></patcit><patcit num="17"><text>U.S. Pat. No. 5,457,862</text></patcit><patcit num="18"><text>U.S. Pat. No. 5,473,503</text></patcit><patcit num="19"><text>U.S. Pat. No. 5,729,428</text></patcit><patcit num="20"><text>U.S. Pat. No. 5,812,367</text></patcit><patcit num="21"><text>U.S. Patent Publication No. 2007/0064376</text></patcit><patcit num="22"><text>U.S. Pat. No. 6,674,635</text></patcit><patcit num="23"><text>U.S. Patent Application Publication No. 2006/0038304</text></patcit></p>

<p num="0003"><nplcit num="1"><text>Bruanauer, Emmet, and Teller, Journal of the Chemical Society of America, Vol.60,1938, p.309</text></nplcit><nplcit num="2"><text>Pozdeev-Freeman et al., "Critical Oxygen Content of Porous Anodes of Solid Tantalum Capabilities", Journal of Materials Science: Materials in Electrical Engineering 9, (1998) 309-311</text></nplcit></p>

<p num="0004"> Therefore, there is currently a need for solid electrolytic capacitors with improved properties.</p>

<p num="0005"> According to one embodiment of the present invention, a solid electrolytic capacitor including a sintered porous anode, a dielectric layer overlaid on the anode body, and a solid electrolyte overlaid on the dielectric layer is disclosed. The solid electrolyte comprises a conductive polymer and a nonionic surfactant having a hydrophilic / lipophilic balance ("HLB") of about 10 to about 20 and a molecular weight of about 100 to about 10,000 grams per mole. The nonionic surfactant has a hydrophobic base and a hydrophilic chain containing an alkoxy moiety.</p><p num="0006"> According to another embodiment of the present invention, a step of anodizing the sintered porous anode to form a dielectric layer overlaid on the anode, a step of forming a first layer containing a conductive polymer, and subsequent steps. A step of forming a solid electrolyte on the dielectric layer by a step including a step of forming a second layer which is overlapped on the first layer and contains the nonionic surfactant as described above. A method for forming a solid electrolytic capacitor including the present invention is disclosed.</p><p num="0007"> Other features and embodiments of the present invention are shown in more detail below.</p><p num="0008"> A complete and feasible disclosure of the invention to those skilled in the art, including its best mode, is illustrated in more detail by the rest of the specification with reference to the accompanying figures.</p><p num="0009"> The repeated use of reference characters in the specification and drawings is intended to represent the same or similar features or elements of the invention.</p>

<figref num="1">It is the schematic of one Embodiment of the capacitor which can be formed by this invention.</figref>

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

In general, the present invention relates to capacitors having excellent electrical properties. The inventor has found that the ability to achieve a capacitor with such performance may be due, at least in part, to a unique and controlled combination of features associated with the solid electrolyte of the capacitor. More specifically, the solid electrolyte is formed from a combination of a conductive polymer with a hydrophobic base (eg, a long-chain alkyl group or an alkylated allylic group) and a nonionic surfactant having a hydrophilic chain. .. Nonionic surfactants are generally hydrophilic in nature, comparing about 10 to about 20, in some embodiments about 12 to about 19, and in some embodiments about 14 to about 18. Has a highly hydrophilic / lipophilic balance ("HLB"). The HLB index is known in the art and is a scale that measures the balance between hydrophilic and lipophilic solution tendencies of compounds. One method for determining the HLB value of a nonionic surfactant is provided as follows. HLB = 20^*Mh / M Here, Mh is the molecular weight of the hydrophilic portion of the surfactant, and M is the molecular weight of the surfactant. The HLB scale therefore ranges from 0 to 20, with lower numbers representing higher lipophilic tendencies and higher numbers representing higher hydrophilic tendencies. Although not intended to be limited by theory, it is believed that nonionic surfactants with such HLB values can increase the degree of contact between the polymer and the surface of the internal dielectric, and are internal. Dielectrics are typically relatively smooth in nature as a result of higher forming voltages. This unexpectedly improves electrical properties such as increased breakdown voltage, surge current, capacitance, and / or wet-to-dry capacitance of the resulting capacitor, as well as reduced equivalent series resistance ("ESR"). Nonionic surfactants may also have a molecular weight high enough to minimize chemical decomposition during the formation of the capacitor, but low enough so that it does not interfere poorly with the performance of the conductive polymer. it can. For example, the molecular weight of a surfactant is typically about 100 to 10,000 grams per mole, about 200 to about 2,000 in some embodiments, about 400 to about 5,000 in some embodiments, and some embodiments. The form is about 500 to about 2,500.

According to the present inventor, a nonionic surfactant having a specific combination of HLB and molecular weight described above is ethoxy (-CH).₂CH₂-O-) and / or propoxy portion (-CH₂CH₂-CH₂It was found more specifically that it contains an alkoxy moiety such as -O-). Some examples of such polymers include, for example, ethoxylated or propoxylated alkylphenols, ethoxylated or propoxylated C.₆-C₂₄Fat alcohol, general formula: CH₃-(CH₂)_10-16-(OC₂H₄)_1-25Polyoxyethylene glycol alkyl ethers with -OH (eg octaethylene glycol monododecyl ethers and pentaethylene glycol monododecyl ethers), general formula: CH₃-(CH₂)_10-16-(OC₃H₆)_1-25Polyoxypropylene glycol alkyl ether with -OH, general formula: C₈H₁₇-(C₆H₄)-(OC₂H₄)_1-25Polyoxyethylene glycol octylphenol ether with -OH (eg Triton® X-100), the following general formula: C₉H₁₉-(C₆H₄)-(OC₂H₄)_1-25Polyoxyethylene glycol alkylphenol ether with -OH (eg nonoxynol-9), polyoxyethylene glycol sorbitan alkyl ester (eg polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate, Polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monooleate, PEG-20 methylglucose distearate, PEG-20 methylglucose sesquistearate, PEG-80 castor oil, PEG-20 castor C such as oils, PEG-3 castor oil, PEG600 dioreato, and PEG400 dioreato) and polyoxyethylene glycol alkyl esters (eg, polyoxyethylene-23 glycol laurate and polyoxyethylene-20 glycol stearate).₈-C₂₄Polyethylene glycol ester of fatty acids, C₈-C₂₄Polyoxyethylene glycol ethers of fatty acids (eg, polyoxyethylene-10 cetyl ether, polyoxyethylene-10 stearyl ether, polyoxyethylene-20 cetyl ether, polyoxyethylene-10 oleyl ratel, 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 (eg Poloxamer), and mixtures thereof. Including.

Various embodiments of the present invention will now be described in more detail below.

I.<u style="single">anode</u> The anode is formed from the valve metal composition. The specific charge of the composition is about 2,000 μF^*Approximately 250,000 μF from V / g^*It may be different like V / g. Approximately 60,000 microfarads per gram in certain embodiments, such as when capacitors are used in high voltage applications.^*Bolt ("μF"^*V / g ") or less, in some embodiments from about 2,000 to about 50,000 μF^*V / g, and in some embodiments about 5,000 to about 30,000 μF^*Powders with a low specific charge such as V / g are used. Of course, about 60,000 microfarads per gram^*Bolt ("μF"^*V / g ") or greater, in some embodiments approximately 70,000 or greater, in some embodiments approximately 80,000 μF^*V / g or greater, and in some embodiments from about 100,000 to about 250,000 μF^*High specific charge powders such as V / g can be used. As is known in the art, the specific charge can be determined by multiplying the anodizing voltage used by the capacitance and then dividing this product by the weight of the anodized electrode body.

Valve metal compositions generally include valve metals (ie, oxidizable metals) such as tantalum, niobium, aluminum, hafnium, titanium, alloys of these, oxides of these, and nitrides of these. Contains valve metal-based compounds. For example, the valve metal composition is 1: 1.0 ± 1.0, in some embodiments 1: 1.0 ± 0.3, in some embodiments 1: 1.0 ± 0.1, and in some embodiments 1: 1.0 ± 0.05. It can contain a conductive oxide of niobium such as niobium oxide having an atomic ratio of niobium to oxygen. Niobium oxide is NbO_0.7, NbO_1.0, NbO_1.1, And NbO₂Can be. Examples of such valve metal oxides are US Pat. No. 6,322,912 granted to Fife, US Pat. No. 6,391,275 granted to Fife et al., And US Pat. No. 6,416,730 granted to Fife et al. US Pat. No. 6,527,937 granted to Fife et al., US Pat. No. 6,576,099 granted to Kimmel et al., US Pat. No. 6,592,740 granted to Fife et al., United States granted to Kimmel et al. US Pat. No. 6,639,787 and US Pat. No. 7,220,397 granted to Kimmel et al., US Patent Application Publication No. 2005/0019581 Granted to Schnitter, US Patent Application Publication Granted to Schnitter et al. It is described in 2005/0103638 and US Patent Application Publication No. 2005/0013765 granted to Thomas et al.

A powder of the valve metal composition is commonly used to form the anode. The powder can contain particles of any of various shapes such as nodular, horny, flaky, etc., as well as mixtures thereof. In certain embodiments, the particles can have a flaky morphology in that they retain a relatively flat or platelet form. Such particles can provide a short transfer line between the outer surface and the inner surface of the anode and can provide a highly conductive and dense wire-to-anode connection with high conductivity. In particular, this can help increase the breakdown voltage (the voltage at which the capacitor fails) and lower the equivalent series resistance ("ESR"). The particles can also increase the specific charge of the anode when anodized at a higher voltage, thereby increasing the energy density.

When used, the flaky particles are substantially flat. The degree of flatness is generally determined by the "aspect ratio", i.e. the average diameter or width ("D / T") of the particles divided by the average thickness. For example, the aspect ratio of the particles can be from about 2 to about 100, in some embodiments from about 3 to about 50, and in some embodiments from about 4 to about 30. The particles are also about 0.5 to about 10.0 m²/ g, about 0.7 to about 5.0 m in some embodiments²/ g, and in some embodiments about 1.0 to about 4.0 m²Can have a specific surface area of / g. The term "specific surface area" is generally determined by the Physical Gas Adsorption (BET) method using nitrogen as the adsorption gas in Bruanauer, Emmet, and Teller, Journal of the American Society of Chemistry, Vol.60, 1938, p.309. Means the surface area. The test can be performed with a MONOSORB® specific surface area analyzer available from QUANTACHROME Corporation in Shoset, NY, USA, which is a fluid mixture of adsorbent and inert transport gas (eg, helium). The amount of adsorbent nitrogen gas adsorbed on the solid surface is measured by sensing the change in thermal conductivity of the solid.

Bulk density (also known as Scott density) is also typically about 0.1 to about 2 grams (g / cm) per cubic centimeter.³), Approximately 0.2 g / cm in some embodiments³From about 1.5g / cm³, And in some embodiments about 0.4 g / cm³From about 1g / cm³Is. "Bulk density" can be determined using a flowmeter funnel and density cup. More specifically, the powder sample can be poured into the cup through a funnel until the sample completely fills the perimeter of the cup and overflows, after which the sample is flush with the top of the cup. Can be flattened with a spatula without shaking. The flattened sample is transferred to a scale and weighed with an accuracy of 0.1 grams to determine the density value. Such devices are commercially available from Alcan Aluminum Corporation, located in Elizabeth, NJ, USA. The particles also have an average size (eg, width) of about 0.1 to about 100 micrometers, in some embodiments about 0.5 to about 70 micrometers, and in some embodiments about 1 to about 50 micrometers. be able to.

Certain additional ingredients can be included in the powder to facilitate the construction of the anode. For example, the powder can optionally be mixed with a binder and / or lubricant to ensure that the particles adhere well to each other as they are pressed to form the anode body. Preferred binders are, for example, cellulose polymers such as poly (vinyl butyral), poly (vinyl acetate), poly (vinyl alcohol), poly (vinylpyrrolidone), carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and methyl hydroxyethyl cellulose. , Atactic polypropylene, polyethylene, polyethylene glycol (eg Carbowax from Dow Chemical Corporation), polystyrene, poly (butadiene / styrene), polyamide, polyimide, and polyacrylamide, high molecular weight polyether, ethylene oxide and propylene oxide copolymers. , Polytetrafluoroethylene, polyvinylidene fluoride, and fluoropolymers such as fluoroolefin copolymers, sodium polyacrylate, poly (lower alkyl acrylate), poly (lower alkyl methacrylate) and copolymers of lower alkyl acrylates and methacrylates. Acrylic polymers, as well as fatty acids and waxes such as stear and other soap fatty acids, vegetable wax, microwax (pure paraffin), etc. can be included. The binder can be dissolved and dispersed in the solvent. An exemplary solvent can include water, alcohol and the like. When utilized, the percentage of binder and / or lubricant can vary from about 0.1% to about 8% by weight of total mass. However, it should be understood that binders and / or lubricants are not always required in the present invention.

The resulting powder can then be compressed and pelleted using any conventional powder press device. For example, a press mold can be used, which is a single station compression press accommodating a die and one or more punches. Alternatively, anvil compression press molds can be used, which use only a die and a single underside punch. Single station compression press molds are cams, toggles / knuckles and eccentrics with various functions such as single acting, double acting, floating die, movable platen, opposed ram, screw, impact, hot press, coining or sizing. / Available in some basic types like crank press. The powder can be compressed around the anode lead wire. The wire can be formed from tantalum, niobium, aluminum, hafnium, titanium and any other conductive material such as these conductive oxides and / or nitrides.

After compression, the resulting anode body can then be die-cut into any desired shape such as square, rectangle, circle, oval, triangle, hexagon, octagon, heptagon, pentagon and the like. The anode body also has in that it contains one or more wrinkles, grooves, recesses, or depressions, increases the surface-to-volume ratio, minimizes ESR, and extends the frequency response of the capacitance. It can have a "grooved" shape. The anode body can then undergo a heating step in which most, if not all, of all binders / lubricants are removed. For example, the anode body is typically heated by an oven operating at a temperature of about 150 ° C to about 500 ° C. Alternatively, the binder / lubricant can also be removed by contacting the pellet with an aqueous solution as described in US Pat. No. 6,197,252 granted to Bishop et al.

The pellets are then sintered to form a porous, integrated mass. Sintering temperature, atmosphere, and time may depend on various factors such as anode type, anode size, and so on. Typically, sintering takes about 5 to about 100 minutes, and in some embodiments about 30 to about 60 minutes, from about 800 ° C to 1900 ° C, and in some embodiments about 1000. It is carried out at temperatures from ° C to about 1500 ° C, and in some embodiments from about 1100 ° C to about 1400 ° C. If desired, sintering can be performed in an atmosphere that limits the transfer of oxygen atoms to the anode. For example, sintering can be performed in a reducing atmosphere such as vacuum, inert gas, hydrogen and the like. The reducing atmosphere can be 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 (eg argon or nitrogen) can also be used.

The anode can also have a relatively low carbon and oxygen content. For example, the anode can have no more than about 50 ppm carbon, and in some embodiments no more than about 10 ppm carbon. Similarly, the anode can have no more than about 3500 ppm oxygen, in some embodiments no more than about 3000 ppm oxygen, and in some embodiments about 500 to about 2500 ppm oxygen. The oxygen content can be measured by a "LECO oxygen analyzer" and contains oxygen in natural oxides on the tantalum surface and bulk oxygen in the tantalum particles. The bulk oxygen content is controlled by the period of the tantalum crystal lattice, which increases linearly by increasing the oxygen content of the tantalum until a dissolution limit is reached. This method is described in Pozdeev-Freeman et al., "Critical Oxygen Content of Porous Anodes of Solid Tantalum Capabilities," Journal of Materials Science: Materials in Electrical Engineering 9, (1998) 309-311, and X-ray diffraction. The period of the tantalum crystal lattice was measured using analysis (XRDA). Oxygen in sintered tantalum anodes can be limited to thin natural surface oxides, but most tantalum is practically oxygen-free.

As mentioned above, the anode leads can also be connected to the anode body extending longitudinally from it. Anode leads can be in the form of wires, sheets and the like, and can be formed from valve metal compounds such as tantalum, niobium, niobium oxide and the like. Reed connection can be achieved using known techniques such as welding the reed to the body or incorporating it into the anode body during formation (eg, prior to compression and / or sintering). ..

II.<u style="single">Dielectric</u> The anode is also coated with a dielectric. The dielectric can be formed by anodizing ("anodizing") the sintered anode so that the dielectric layer is formed on and / or in the anode. For example, the tantalum (Ta) anode is tantalum pentoxide (Ta).₂O₅) Can be anodized. Typically, anodization is carried out by first adding the solution to the anode, such as by immersing the anode in an electrolyte. Solvents such as water (eg, deionized water) are commonly used. Compounds can be used to increase ionic conductivity, which can be dissolved in a solvent to form ions. Examples of such compounds include, for example, acids as described below for electrolytes. For example, the acid (eg, phosphoric acid) is from about 0.01 weight percent to about 5 weight percent of the anodic solution, in some embodiments from about 0.05 weight percent to about 0.8 weight percent, and in some embodiments about 0.1 weight percent. It can constitute from weight percent to about 0.5 weight percent. If desired, a mixture of acids can also be used.

The current passes through the anodizing solution and forms a dielectric layer. The value of the forming voltage controls the thickness of the dielectric layer. For example, the power supply can first be set in constant current mode until the required voltage is reached. The power supply can then switch to constant potential mode to ensure that the desired dielectric thickness is formed over the surface of the anode. Of course, other known methods such as pulse or step potentiometric methods can also be used. The voltage at which anodization occurs typically ranges from about 4 to 250 V, and in some embodiments from about 9 to about 200 V, and in some embodiments from about 20 to about 150 V. During oxidation, the anodized solution is at or above about 30 ° C, from about 40 ° C to about 200 ° C in some embodiments, and from about 50 ° C to about 100 ° in some embodiments. It can be maintained at a high temperature such as C. Anodization can also be performed at ambient temperature or below. The resulting dielectric layer can be formed on the surface of the anode and in its pores.

Although not required, in certain embodiments, the dielectric layer has a first portion overlaid on the outer surface of the anode and a second portion overlaid on the inner surface of the anode. , Can have different thicknesses over the anode. In such an embodiment, the first portion is selectively formed so that its thickness is larger than the thickness of the second portion. However, it should be understood that the thickness of the dielectric layer needs to be uniform within a particular region. A certain portion of the dielectric layer adjacent to the outer surface may actually be thinner than, for example, a certain portion of the layer on the inner surface, and vice versa. Nevertheless, the dielectric layer can be formed such that at least a portion of the layer on the outer surface has a thickness greater than at least a portion on the inner surface. The actual difference in these thicknesses may vary depending on the particular application, but the ratio of the thickness of the first part to the thickness of the second part is typically about 1.2 to about 40, in part. In the embodiment of about 1.5 to about 25, and in some embodiments about 2 to about 20.

A multi-step process is commonly used to form dielectric layers with different thicknesses. At each stage of the process, the sintered anode is anodized ("anodized") to form a dielectric layer (eg, tantalum pentoxide). During the first stage of anodization, about 1 to about 90 volts, in some embodiments about 2 to about 50 volts, to ensure that the desired dielectric thickness is achieved for the inner region. And in some embodiments, relatively small forming voltages, such as forming voltages ranging from about 5 to about 20 volts, are typically used. The sintered body is then anodized in the second step of the process, allowing the thickness of the dielectric to be increased to the desired level. This is generally the first in forming voltages ranging from about 50 to about 350 volts, in some embodiments from about 60 to about 300 volts, and in some embodiments from 70 to about 200 volts. Achieved by anodizing in the electrolyte at a higher voltage than used during the stage. During the first and / or second stage, the electrolyte is from about 15 ° C to about 95 ° C, in some embodiments from about 20 ° C to about 90 ° C, and in some embodiments about 25 ° C. The temperature can be maintained in the range of ° C to about 85 ° C.

The electrolytes used during the first and second stages of the anodizing step may be the same or different. However, it is typically desirable to use different solutions to help further facilitate the achievement of higher thicknesses in the outer portion of the dielectric layer. For example, the electrolyte used in the second stage has a lower ionic conductivity than the electrolyte used in the first stage, preventing a significant amount of oxide film from forming on the inner surface of the anode. Can be desirable. In this regard, the electrolyte used in the first stage can contain acidic compounds such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, boronic acid and the like. Such electrolytes are about 0.1 to about 100 mS / cm determined at a temperature of 25 ° C, about 0.2 to about 20 mS / cm in some embodiments, and about 1 to about 10 mS / cm in some embodiments. Can have a conductivity of cm. The electrolyte used in the second stage typically contains a salt of a weak acid such that the concentration of hydronium ions increases in the pores as a result of charge passage through it. Ion transport or diffusion is such that the weak acid anion moves into the pores as the charge needs to be balanced. As a result, the concentration of the major conductive species (hydronium ions) is reduced in establishing an equilibrium between the hydronium ions, acid anions, and non-dissociating acids, thus forming weaker conductive species. The reduced concentration of conductive species results in a relatively high voltage drop in the electrolyte, which prevents yet another anodization inside, while the thicker oxide layer is higher in the continuous high conductivity region. It is built outside the forming voltage. Preferred weak acid salts can include, for example, ammonium or alkali metal salts such as boric acid, boronic acid, acetic acid, oxalic acid, lactic acid, adipic acid (eg, sodium, potassium, etc.). Particularly suitable salts include sodium tetraborate and ammonium pentaborate. Such electrolytes are typically about 0.1 to about 2.0 mS / cm as determined at a temperature of 25 ° C, and in some embodiments about 0.

If desired, each stage of anodization can be repeated over one or more cycles to achieve the desired dielectric thickness. In addition, the anode can also be rinsed or washed with another solvent (eg, water) after the first and / or second steps to remove the electrolyte.

III.<u style="single">Solid electrolyte</u> A.<u style="single">Conductive polymer</u> As mentioned above, the solid electrolyte is overlaid on a dielectric that generally acts as a cathode for the capacitor. The solid electrolyte contains a conductive polymer, which is typically π-conjugated and has post-oxidation or reduction conductivity such as conductivity of at least about 1 μS / cm. Examples of such π-conjugated conductive polymers include, for example, polyheterocyclic compounds (eg, polypyrrole, polythiophene, polyaniline, etc.), polyacetylenes, poly-p-phenylenes, polyphenylates and the like. In one embodiment, for example, the polymer is a substituted polythiophene such that it has the following general structure:<img id="000002" he="35" wi="35" file="JP6317552B2_D0001.tif" img-format="tif" img-content="drawing" />Where T is O or S and D is optionally substituted C₁From C₅Alkylene groups (eg, methylene, ethylene, n-propylene, n-butylene, n-pentylene, etc.) and R₇Is a linear or branched arbitrarily substituted C₁From C₁₈Alkyl groups of (eg, methyl, ethyl, n- or iso-propyl, 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-octadecil, etc.), optionally substituted C₅From C₁₂Cycloalkyl groups (eg, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, etc.), optionally substituted C₆From C₁₄Aryl groups (eg, phenyl, naphthyl, etc.), optionally substituted C₇From C₁₈Aralkyl groups (eg, benzyl, o-, m-, p-tolyl, 2,3-, 2,4-, 2,5-, 2-6, 3-4-, 3,5-xylyl, mesityl, Other), optionally replaced C₁From C₄The hydroxyalkyl or hydroxyl group of, q is an integer of 0 to 8, 0 to 2 in some embodiments, and 0 in some embodiments, n is 2 to 5,000, in part. 4 to 2,000 in embodiments of, and 5 to 1,000 in some embodiments. Radical "D" or "R"₇Examples of substituents are, for example, alkyl, cycloalkyl, aryl, aralkyl, alkoxy, halogen, ether, thioether, disulfide, sulfoxide, sulfonate, sulfonate, amino, aldehyde, keto, carboxylic acid ester, carboxylic acid, Includes carbonates, carboxylates, cyanos, alkylsilanes and alkoxysilane groups, carboxylamide groups and the like.

A particularly suitable thiophene polymer is C in which "D" is optionally substituted.₂From C₃It is an alkylene group of. For example, the polymer can be an optionally substituted poly (3,4-ethylenedioxythiophene), which has the following general structure:<img id="000003" he="39" wi="34" file="JP6317552B2_D0001.tif" img-format="tif" img-content="drawing" />

Methods of forming conductive polymers as described above are known in the art. For example, U.S. Pat. No. 6,987,663 granted to Merker et al., Which is incorporated herein by reference in its entirety for all purposes, provides a variety of polythiophenes substituted from monomeric precursors. Explains the technology. The monomer precursor has, for example, the following structure.<img id="000004" he="32" wi="27" file="JP6317552B2_D0001.tif" img-format="tif" img-content="drawing" />Where T, D, R₇, And q are defined above. A particularly suitable thiophene monomer is C in which "D" is optionally substituted.₂From C₃It is an alkylene group of. For example, optionally substituted 3,4-alkylenedioxythiophene can be used, which has the following general structure:<img id="000005" he="37" wi="22" file="JP6317552B2_D0001.tif" img-format="tif" img-content="drawing" />Where R₇And q are defined above. In one particular embodiment, "q" is 0. One commercially suitable example of 3,4-ethylenedioxythiophene is available from "HC Starck GmbH" under the name Clevios® M. Other suitable monomers are also described in US Pat. No. 5,111,327 granted to Blohm et al. And US Pat. No. 6,635,729 granted to Groenendaal et al. All of these are incorporated herein by reference. Derivatives of these monomers can also be used, which are, for example, dimers or trimers of the above-mentioned monomers. Higher molecular weight derivatives, such as monomer tetramers, pentamers, etc., are suitable for use in the present invention. Derivatives can be made up of the same or different monomer units and used alone and / or mixed with each other and / or monomers. Oxidized or reduced forms of these precursors can also be used.

Various methods can be used to form the conductive polymer layer. For example, the in-situ polymerization layer can be formed by chemically polymerizing the monomers in the presence of an oxidation catalyst. Oxidation catalysts typically transition such as iron (III), copper (II), chromium (VI), cerium (IV), manganese (IV), manganese (VII), or ruthenium (III) cations. Contains metal cations. Dopants can also be used to provide excess charge to the conductive polymer and stabilize the conductivity of the polymer. Dopants typically include inorganic or organic anions such as sulfonic acid ions. In certain embodiments, the oxidation catalyst has both catalytic and doping functions in that it contains cations (eg, transition metals) and anions (eg, sulfonic acids). For example, the oxidation catalyst is an iron (III) halide (eg, FeCl).₃) Like iron (III) cation or Fe (ClO)₄)₃Or Fe₂(SO₄)₃It can be an iron (III) salt of another inorganic acid such as, and a transition metal salt containing an iron (III) salt of an inorganic acid containing an organic acid and an organic radical. An example of an iron (III) salt of an inorganic acid with organic radicals is C.₁From C₂₀Includes iron (III) salts of alkanol sulfate monoesters (eg, iron (III) salts of lauryl sulfate). Similarly, an example of an iron (III) salt of an organic acid is, for example, C.₁From C₂₀Iron (III) salts of alkane sulfonic acid (eg, methane, ethane, propane, butane, or dodecane sulfonic acid), aliphatic perfluorosulfonic acid (eg, trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, or perfluorooctanesulfonic acid) Iron (III) salt, aliphatic C₁From C₂₀Iron (III) salt of carboxylic acid (eg 2-ethylhexylcarboxylic acid), iron (III) salt of aliphatic perfluorocarboxylic acid (eg trifluoroacetic acid or perfluorooctanoic acid), C₁From C₂₀Iron (III) salt of aromatic sulfonic acid (eg, benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid) optionally substituted with an alkyl group, cycloalcansulfonic acid (eg For example, it contains an iron (III) salt of camphorsulfonic acid). Mixtures of these iron (III) salts described above can also be used. Iron (III) -p-toluenesulfonate, iron (III) -o-toluenesulfonate, and mixtures thereof are particularly suitable. One commercially suitable example of iron (III) -p-toluenesulfonate is available from Heraeus Clebios under the name Clevious® C.

The oxidation catalyst and the monomer can be added either sequentially or together to initiate the polymerization reaction. Suitable addition techniques for adding these compounds include screen printing, dipping, electrophoretic coating, and spraying. As an example, the monomer can first be mixed with an oxidation catalyst to form a precursor solution. With the mixture formed, it can be added to the anode so that a conductive coating is formed on the surface and then polymerized. Alternatively, the oxidation catalyst and monomer can be added sequentially. In one embodiment, for example, the oxidation catalyst is dissolved in an organic solvent (eg butanol) and then added as an immersion solution. The anode section is then dried and the solvent can be removed from it. These moieties can then be immersed in a solution containing the monomer. In any case, the polymerization is typically from about -10 ° C to about 250 ° C, and in some embodiments from about 0 ° C to about 200 ° C, depending on the oxidant used and the desired reaction time. It is carried out at the temperature of. Suitable polymerization techniques as described above can be described in more detail in US Pat. No. 7,515,396 granted to Biler. Yet another method for adding such a conductive coating is granted to Sakata et al., U.S. Pat. No. 5,457,862, U.S. Pat. No. 5,473,503, granted to Sakata et al., And Sakata et al. Can be described in U.S. Pat. No. 5,729,428 and U.S. Pat. No. 5,812,367 granted to Kudoh et al. Is incorporated by.

In addition to in-situ applications, conductive polymer solid electrolytes can also be added in the form of dispersants of conductive polymer particles. One benefit of using dispersants is that the dispersants produce ion species during in-situ polymerization that can cause dielectric breakdown under high electric fields due to ion transfer (eg, Fe).²⁺Or Fe³⁺) Can be minimized. Therefore, by adding a conductive polymer as a dispersant rather than by in-situ polymerization, the resulting capacitor can exhibit a relatively high breakdown voltage. To allow good impregnation of the anode, the particles used in the dispersant are typically from about 1 to about 150 nanometers, and in some embodiments from about 2 to about 50 nanometers, and some. In the embodiment of, it has a small size such as an average size (eg, diameter) of about 5 to about 40 nanometers. The particle size can be determined using known techniques such as ultracentrifuges, laser diffraction, and the like. The shape of the particles may also be different. In one particular embodiment, for example, the particles are spherical in shape. However, it should be understood that other shapes such as plates, rods, discs, bars, tubes, irregular shapes, etc. are also considered by the present invention. The concentration of the dispersant particles may vary depending on the desired viscosity of the dispersant and the particular method by which the dispersant will be added to the capacitor. However, typically, the particles make up about 0.1 to about 10 weight percent of the dispersant, about 0.4 to about 5 weight percent in some embodiments, and about 0.5 to about 4 weight percent in some embodiments. To do.

Dispersants also generally contain counterions that enhance the stability of the particles. That is, the conductive polymer (eg, polythiophene or a derivative thereof) typically has a charge on the main polymer chain, which is neutral or positive (cationic). Polythiophene derivatives typically carry a positive charge on the main polymer chain, for example. In some cases, the polymer can carry positive and negative charges in the structural unit, the positive charge is located on the backbone and the negative charge is a radical such as a sulfonate or a cariboxylate group. Arbitrarily located on the "R" substituent. The positive charge of the main chain can be partially or wholly saturated with anionic groups optionally present on the radical "R". Overall, polythiophenes can be cations, neutrals, or even anions in these cases. Nonetheless, they are all considered cationic polythiophenes if the polythiophene backbone has a positive charge.

The counterion can be a monomer or polymer anion that cancels the charge of the conductive polymer. Polymer anions include, for example, polymer carboxylic acids (eg, polyacrylic acid, polymethacrylic acid, polymer lainic acid, etc.), polymer sulfonic acids (eg, polystyrene sulfonic acid ("PSS"), polyvinyl sulfonic acid, etc.). Can be an anion. The acid can also be a copolymer such as a copolymer of vinylcarboxylic acid and vinylsulfonic acid with other polymerizable monomers such as acrylic acid ester and styrene. Similarly, preferred monomer anions are, for example, C.₁From C₂₀Alkane sulfonic acid (eg, dodecane sulfonic acid), aliphatic perfluorosulfonic acid (eg, trifluoromethanesulfonic acid, perfluorobutanesulfonic acid or perfluorooctanesulfonic acid), aliphatic C₁From C₂₀Carboxylic acid (eg 2-ethyl-hexylcarboxylic acid), aliphatic perfluorocarboxylic acid (eg trifluoroacetic acid or perfluorooctanoic acid), C₁From C₂₀Aromatic sulfonic acid optionally substituted by the alkyl group of (eg, benzene sulfonic acid, o-toluene sulfonic acid, p-toluene sulfonic acid, or dodecyl benzene sulfonic acid), cycloalcan sulfonic acid (eg, camphor sulfonic acid) Or it contains anions such as tetrafluoroborate, hexafluorophosphate, perchlorate, hexafluoroantimonate, hexafluorohydrate or hexachloroantimonate). Particularly suitable counterions are polymeric anions such as polymeric carboxylic acids or sulfonic acids (eg, polystyrene sulfonic acids ("PSS")). The molecular weight of such polymer anions typically ranges from about 1,000 to about 2,000,000, and in some embodiments from about 2,000 to about 500,000.

When used, the weight ratio of such counterion to conductive polymer in the dispersant and the resulting layer is typically from about 0.5: 1 to about 50: 1, and in some embodiments from about 1: 1. About 30: 1, and in some embodiments about 2: 1 to about 20: 1. The weight of the corresponding conductive polymer, which means the weight ratio described above, means the weighted portion of the monomers used together, assuming complete conversion occurs during polymerization.

In addition to the conductive polymer and counterions, the dispersant also contains one or more binders to further enhance the adhesion of the polymer layer and also increase the stability of the particles within the dispersant. be able to. Binders include polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl chloride, polyvinyl acetate, polyvinylbutyrate, polyacrylic acid ester, polyacrylic acid amide, polymethacrylic acid ester, polymethacrylic acid amide, polyacrylonitrile, styrene / acrylic acid ester. , Vinyl acetate / acrylic acid ester and ethylene / vinyl acetate copolymer, polybutadiene, polyisoprene, polystyrene, polyether, polyester, polycarbonate, polyurethane, polyamide, polyimide, polysulfone, melamine formaldehyde resin, epoxide resin, silicone resin or cellulose Such properties can be organic. Crosslinkers can also be used to enhance the adhesive function of the binder. Such cross-linking agents include, for example, functional group silanes such as melamine compounds, masked isocyanates or 3-glycidoxypropyltrialkoxysilanes, tetraethoxysilanes and tetraethoxysilane hydrolysates, or polyurethanes, polyacrylates or polyolefins. Crosslinkable polymers can be included.

Dispersants can also be used to facilitate the formation of solid electrolytes and the ability to add them to the anode. Preferred dispersants are aliphatic alcohols (eg, methanol, ethanol, i-propanol, and butanol), aliphatic ketones (eg, acetone and methyl ethyl ketone), aliphatic carboxylic acid esters (eg, ethyl acetate and butyl acetate), aromatics. Group hydrocarbons (eg, toluene and xylene), aliphatic hydrocarbons (eg, hexane, heptane, and cyclohexane), chlorinated hydrocarbons (eg, dichloromethane and dichloroethane), aliphatic nitriles (eg, acetonitrile), aliphatic sulfoxides. And solvents (eg, dimethylsulfoxide and sulfolane), aliphatic carboxylic acid amides (eg, methylacetamide, dimethylacetamide and dimethylformamide), aliphatic and aromatic aliphatic ethers (eg, diethyl ether and anisole), water, and above. Includes a solvent such as a mixture of any of the solvents in.

In addition to those mentioned above, other ingredients can also be used in the dispersant. For example, conventional fillers can be used, which are from about 10 nanometers to about 100 nanometers, in some embodiments from about 50 nanometers to about 50 micrometers, and in some embodiments about about. It has a size of 100 nanometers to about 30 micrometers. Examples of such fillers include calcium carbonate, silicates, silica, calcium sulphate or barium sulphate, aluminum hydroxide, fiberglass or valves, wood flour, cellulose powder carbon black, conductive polymers, and more. The filler can be introduced into the dispersant in powder form, but can also be present in another form, such as fiber.

Organic functional silanes or their hydrolysates, such as 3-glycidoxypropyltrialkoxysilane, 3-aminopropyl-triethoxysilane, 3-mercaptopropyl-trimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyl. Adhesives such as trimethoxysilane or octylriethoxysilane can also be used. Dispersants are also ether group-containing compounds (eg, tetrahydrofuran), lactone group-containing compounds (eg, γ-butyrolactone or γ-valerolactone), amide or lactam group-containing compounds (eg, caprolactam, N-methylcaprolactam, N, N-dimethylacetamide, N-methylacetamide, N, N-dimethylformamide (DMF), N-methylformamide, N-methylformanilide, N-methylpyrrolidone (NMP), N-octylpyrrolidone, or pyrrolidone), sulfone and Sulfoxide (eg, sulfolane (tetramethylenesulfone) or dimethylsulfoxide (DMSO)), sugar or sugar derivative (eg, saccharose, glucose, fructose, or lactose), sugar alcohol (eg, sorbitol or mannitol), furan derivative (eg, eg It can contain additives that increase conductivity, such as 2-furancarboxylic acid or 3-furancarboxylic acid), alcohols (eg, ethylene glycol, glycol, di- or triethylene glycol).

Polymer dispersants use a variety of known techniques such as spin coating, impregnation, injection, dripping addition, injection, spraying, doctabrading, brushing, printing (eg inkjet, screen, or pad printing), or immersion. Can be added. The viscosity of the dispersant is typically from about 0.1 to about 100,000 mPas (100s), although it may vary depending on the additional technology used.^-1In some embodiments it is about 1 to about 10,000 mPas, in some embodiments it is about 10 to about 1,500 mPas, and in some embodiments it is about 100 to about 1000 mPas. In the added state, the layer can be dried and / or washed. One or more additional layers can also be formed in this way to achieve the desired thickness. Typically, the overall thickness of the layer formed by this particle dispersant is from about 1 to about 50 μm, and in some embodiments about 5 to about 20 μm. The weight ratio of counterion to conductive polymer is also about 0.5: 1 to about 50: 1, in some embodiments about 1: 1 to about 30: 1, and in some embodiments about 2: 1. From about 20: 1.

B.<u style="single">Nonionic surfactant</u> Nonionic surfactants as described in detail above are also included in the solid electrolyte. A variety of different techniques can generally be used to incorporate surfactants into solid electrolytes. In certain embodiments, for example, the nonionic surfactant is readily incorporated into any conductive polymer layer (eg, in-situ polymerization or prepolymerized particle dispersant) formed by the methods described above. be able to. In such embodiments, the concentration of the nonionic surfactant in the layer is from about 1 weight percent to about 50 weight percent, in some embodiments from about 5 weight percent to about 40 weight percent, and in some. In the embodiment of, it can be from about 10 weight percent to about 30 weight percent.

However, in other embodiments, the nonionic surfactant can be added after the initial polymer dispersant has been formed. In such embodiments, the techniques used to add the nonionic surfactant may differ. For example, surfactants are in the form of liquid solutions using various methods such as water immersion, immersion, injection, dripping, ejection, spraying, diffusion, coating, or printing, such as inkjet, screen printing, or tampon printing. Can be added with. Solvents known to those of skill in the art, such as water, alcohol, or mixtures thereof, can be used in the solution. Concentrations of nonionic surfactants in such solutions typically range from about 5 weight percent to about 95 weight percent of the solution, and in some embodiments from about 10 weight percent to about 70 weight percent, and one. In the embodiment of the part, it ranges from about 15 weight percent to about 50 weight percent. If desired, such solutions may be almost free of conductive polymers. For example, the conductive polymer may make up about 2 weight percent or less of the solution, about 1 weight percent or less in some embodiments, and about 0.5 weight percent or less in some embodiments. it can.

However, instead, it may be desirable to use a conductive polymer in combination with a nonionic surfactant. For example, in certain embodiments, the "second" layer containing conductive (eg, in-situ polymerization or prepolymerized particles) and nonionic surfactants has a "first" layer on the anode body. After being added, it is added to the anode. When used, the conductive particles in the second polymer layer are as described above, but they do not have to be the same as those optionally used in the first layer. In any case, the concentration of the nonionic surfactant in the second layer is typically from about 1 weight percent to about 50 weight percent, and in some embodiments from about 5 weight percent to about 40 weight percent. And in some embodiments, it is from about 10 weight percent to about 30 weight percent. Similarly, in these embodiments where the nonionic surfactant is used in the second layer, it may be desirable for the first layer to be substantially free of such surfactant. For example, nonionic surfactants are about 2 weight percent or less of the first layer, about 1 weight percent or less in some embodiments, and about 0.5 weight percent or less in some embodiments. Less than can be configured. In the added state, the second layer can be dried and / or washed. One or more additional layers can also be formed in this way to achieve the desired thickness. Typically, the overall thickness of the layer formed by the second polymer dispersant is from about 0.1 to about 5 μm, in some embodiments from about 0.1 to about 3 μm, and in some embodiments from about 0.2 to about. It is 1 μm.

IV.<u style="single">External polymer coating</u> Although not required, an external polymer coating can also be added to the anode body and overlaid on the solid electrolyte. External polymer coatings generally contain one or more layers formed from prepolymerized conductive particles, as described in more detail above. The external coating can penetrate further into the edge region of the capacitor body to increase adhesion to the dielectric and provide a more mechanically robust part, which is equivalent series resistance and leakage current. Can be reduced. The particles used in the outer coating are typically intended to improve the degree of edge coverage rather than impregnation into the anode, so the particles are typically any optional dispersion of the solid electrolyte. It has a larger size than that used for the agent. For example, the outer polymer co -average ratio of the size of particles used in any dispersants average size to the solid electrolyte of the particles used in the coating is typically from about 1.5 to about 30, in some embodiments about 2 From about 20, and in some embodiments about 5 to about 15. For example, the particles used in the dispersant for the outer coating range from about 50 to about 500 nanometers, in some embodiments from about 80 to about 250 nanometers, and in some embodiments from about 100 to about 200 nanometers. Can have an average size.

If desired, a cross-linking agent can also be used in the external polymer coating to increase the degree of adhesion to the solid electrolyte. Typically, the cross-linking agent is added prior to the addition of the dispersant used for the outer coating. Preferred cross-linking agents are described, for example, in US Patent Publication No. 2007/0064376 granted to Mercer et al., Such as amines (eg, diamines, triamines, oligomeric amines, polyamines, etc.), Mg, Al. , Ca, Fe, Cr, Mn, Ba, Ti, Co, Ni, Cu, Ru, Ce or Zn salts or compounds such as polyvalent metal cations, phosphonium compounds, sulfonium compounds and others. Particularly suitable examples are, for example, 1,4-diaminocyclohexane, 1,4-bis (aminomethyl) cyclohexane, ethylenediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1 , 9-Nonandiamine, 1,10-Decandiamine, 1,12-Dodecanediamine, N, N-Dimethylethylenediamine, N, N, N', N'-Tetramethylethylenediamine, N, N, N', N'- Includes tetramethyl-1,4-butanediamine and the like, as well as mixtures thereof.

Crosslinkers are typically from solutions or dispersants that have a pH of 1 to 10, as determined at 25 ° C, 2 to 7 in some embodiments, and 3 to 6 in some embodiments. Will be added. Acidic components can be used to help achieve the desired pH level. Examples of solvents or dispersants for cross-linking agents include water or organic solvents such as alcohols, ketones, carboxylic acid esters and the like. The cross-linking agent is applied to the capacitor body by any known process such as spin coating, impregnation, injection, dripping addition, spray addition, vapor deposition, sputtering, sublimation, knife coating, coating or printing, eg inkjet, screen, or pad printing. Can be added. In the added state, the cross-linking agent can be dried prior to the addition of the polymer dispersant. This step can then be repeated until the desired thickness is obtained. For example, the overall thickness of the entire external polymer coating, including the crosslinker and dispersion layer, ranges 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. In some cases.

V.<u style="single">Other components of the capacitor</u> If desired, the capacitor can also accommodate other layers as known in the art. For example, a protective coating, such as that made of a relatively insulating resin material (natural or synthetic), can optionally be formed between the dielectric and the solid electrolyte. Such materials are greater than about 10 Ω · cm, greater than about 100 in some embodiments, greater than about 1,000 Ω · cm in some embodiments, 1 × 10 in some embodiments.⁵Greater than Ω · cm, and in some embodiments about 1 × 10¹⁰It can have a specific resistance larger than Ω · cm. Some resin materials that can be used in the present invention include, but are not limited to, polyurethanes, polystyrenes, esters of unsaturated or saturated fatty acids (eg, glycerides) and the like. For example, preferred fatty acid esters include, but are not limited to, lauric acid, myristic acid, palmitic acid, stearic acid, eleostearic acid, oleic acid, linoleic acid, linolenic acid, alloylitic acid, shelophosphoric acid and the like. Contains ester. These esters of fatty acids have been found to be particularly useful when used in relatively complex combinations to form "drying oils", which allow the resulting membranes to rapidly form a stable layer. Allows polymerization. Such drying oils can contain mono-, di-, and / or tri-glycerides, which are glycerol backbones with one, two, and three fatty acid residues, respectively. Has. For example, some preferred drying oils that can be used include, but are not limited to, olive oil, linseed oil, castor oil, millet oil, soybean oil, and shellac. These and other protective coating materials are described in detail in US Pat. No. 6,674,635, granted to Fife et al., Which is incorporated herein by reference in its entirety for all purposes.

If necessary, a carbon layer (for example, graphite) and a silver layer can be added to the portion. The silver coating can act as a charge collector for, for example, solderable conductors, contact layers, and / or capacitors, and the carbon coating can limit the contact between the solid electrolyte and the silver coating. Such a coating can cover some or all of the solid electrolyte.

Capacitors can also be terminated, especially when used for surface implementation applications. For example, a capacitor can accommodate an anode termination that is electrically connected to the anode lead of the capacitor element and a cathode termination that is electrically connected to the cathode of the capacitor element. Use any conductive material such as conductive metals (eg copper, nickel, silver, nickel, zinc, tin, palladium, lead, copper, aluminum, molybdenum, titanium, iron, zirconium, magnesium, and alloys thereof). Can form a terminal. Particularly suitable conductive metals include, for example, copper, copper alloys (eg, copper-zincyl, copper-magnesium, copper-zinc, or copper-iron), nickel, and nickel alloys (eg, nickel-iron). The termination thickness is generally chosen to minimize the thickness of the capacitor. For example, the thickness of the termination may range from about 0.05 to about 1 mm, in some embodiments from about 0.05 to about 0.5 mm, and from about 0.07 to about 0.2 mm. An exemplary conductive material is a copper-ferroalloy metal plate available from Wieland (Germany). If necessary, the termination surface can be electroplated with nickel, silver, gold, tin, etc., as is known in the art, to ensure that the final portion is mountable on the circuit board. In one particular embodiment, both ends are plated with nickel and silver flash, respectively, but the mounting surface is also plated with a tin solder layer.

With reference to FIG. 1, one embodiment of the electrolytic capacitor 30 is shown to include an anode termination 62 and a cathode termination 72 in an electrically connected state with the capacitor element 33. The capacitor element 33 has an upper surface 37, a lower surface 39, a front surface 36, and a rear surface 38. Although it can be electrically connected to any of the surfaces of the capacitor element 33, the cathode terminal 72 of the illustrated embodiment is in electrical contact with the bottom surface 39 and the rear surface 38. More specifically, the cathode termination 72 accommodates a first component 73 that is positioned substantially perpendicular to the second component 74. The first component 73 is in electrical contact with and substantially parallel to the lower surface 39 of the capacitor element 33. The second component 74 is in electrical contact with and substantially parallel to the rear surface 38 of the capacitor element 33. Although depicted as united, these parts shall instead be separate parts connected to each other either directly or through additional conductor elements (eg, metal). You should understand that you can.

The anode termination 62 also houses the first component 63, which is positioned substantially perpendicular to the second component 64. The first component 63 is in electrical contact with and substantially parallel to the lower surface 39 of the capacitor element 33. The second component 64 accommodates the region 51 carrying the anode lead 16. In the illustrated embodiment, the region 51 has a "U" shape to further enhance the surface contact and mechanical stability of the lead wire 16.

The termination can be connected to the capacitor element using any technique known in the art. In one embodiment, for example, a lead frame can be provided, which defines a cathode termination 72 and an anode termination 62. A conductive adhesive can first be applied to the surface of the cathode termination 72 to attach the electrolytic capacitor element 33 to the lead frame. The conductive adhesive can include, for example, conductive metal particles containing a resin component. The metal particles can be silver, copper, gold, platinum, nickel, zinc, bismuth and the like. The resin composition can include a thermosetting resin (eg, epoxy resin), a curing agent (eg, acid anhydride), and a binder (eg, silane binder). Preferred conductive adhesives are described in US Patent Application Publication No. 2006/0038304, granted to Osako et al., Which is incorporated herein by reference in its entirety for all purposes. A conductive adhesive can be applied to the cathode termination 72 using any of the various techniques. Printing techniques can be used, for example, with these practical and cost-saving benefits.

In general, various methods can be used to attach the termination to the capacitor. In one embodiment, for example, the second component 64 of the anode termination 62 and the second component 74 of the cathode termination 72 are first bent in the direction of the position shown in FIG. The capacitor element 33 is then positioned above the cathode termination 72 so that its lower surface 39 contacts the adhesive and the anode lead 16 is received by the upper U-shaped region 51. If desired, an insulating material (not shown), such as a plastic pad or tape, is positioned between the bottom surface 39 of the capacitor element 33 and the first component 63 of the anode termination 62 to insulate the anode and cathode terminations. can do.

The anode lead 16 is then electrically connected to the region 51 using any technique known in the art such as mechanical welding, laser welding, conductive adhesives and the like. For example, the anode lead 16 can be welded to the anode termination 62 using a laser. A laser generally houses a resonator that includes a laser medium capable of emitting photons by stimulated emission and an energy source that excites elements of the laser medium. One type of preferred laser is one in which the laser medium is composed of neodymium (Nd) -doped aluminum and yttrium garnet (YAG). Excited particles are neodymium ion Nd³⁺Is. The energy source can provide continuous energy to the laser medium and eject a continuous laser beam or energy discharge to eject a pulsed laser beam. When the anode lead 16 is electrically connected to the anode termination 62, the conductive adhesive can then be cured. For example, heat and pressure can be applied using a heat press to ensure that the electrolytic capacitor element 33 is sufficiently adhered to the cathode termination 72 by the adhesive.

With the capacitor elements attached, the lead frame is encapsulated in a resin casing, which can then be filled with silica or any other known encapsulation material. The width and length of the case may vary depending on the intended use. Preferred casings are, for example, "A", "B", "C", "D", "E", "F", "G", "H", "J", "K", "L", Includes "M", "N", "P", "R", "S", "T", "V", "W", "Y", "X", or "Z" (AVX Corporation) be able to. Regardless of the case size used, the capacitor elements are encapsulated so that at least a portion of the anode and cathode terminations is exposed for mounting on the circuit board. As shown in FIG. 1, for example, the capacitor element 33 is enclosed in the case 28 so that a part of the anode termination 62 and a part of the cathode termination 72 are exposed.

As a result of the present invention, the capacitor assembly can exhibit excellent electrical characteristics as described above. For example, capacitors are about 60 volts or higher, some embodiments about 70 volts or higher, some embodiments about 80 volts or higher, and some embodiments. Can show a relatively high breakdown voltage (voltage at which a capacitor fails), such as about 100 to about 300 volts. Similarly, capacitors are also relatively high, such as about 100 amps or higher, about 200 amps or higher in some embodiments, and about 300 amps to about 800 amps in some embodiments. Can withstand high peak surge currents. The combination of high breakdown voltage and high peak surge current is about 35 volts or higher, in some embodiments about 50 volts or higher, and in some embodiments from about 60 volts to about 200. It can be made possible to use capacitors in high voltage environments such as volts.

Capacitors can also exhibit relatively high capacitance. The dry capacitance can be relatively similar to the wet capacitance, which allows the capacitance loss and / or variation of the capacitor to be negligible in the presence of atmospheric humidity. This performance characteristic is quantified by the "wet-to-dry capacitor percentage", which is determined by the following equation. Wet-to-dry capacitance = (dry capacitance / wet capacitance) x 100

For example, capacitors are about 50 percent or greater, in some embodiments about 60 percent or greater, in some embodiments about 70 percent or greater, and in some embodiments. Can show a wet-to-dry capacitance percentage of about 80% to 100%. Capacitors are also smaller than about 100 milliohms measured at an operating frequency of 100kHz, less than 75 milliohms in some embodiments, about 0.01 to about 60 milliohms in some embodiments, and some embodiments. Can maintain low equivalent series resistance ("ESR"), such as about 0.05 to about 50 milliohms. In some cases, such improved capacitance and ESR performance can remain stable under a variety of different conditions. For example, the capacitance and / or equivalent series resistance of a capacitor is about 25 ° C or less, about 10 ° C or less in some embodiments, about 0 ° C or less in some embodiments, and In some embodiments, with the above range, at low temperatures such as about -7.5 ° C to about -25 ° C (eg, -55 ° C), and even at wide frequencies such as about 10 Hz to about 100 kHz. can do.

Leakage current, which generally means the current flowing from one conductor to an adjacent conductor through an insulator, can also be maintained at relatively low levels. For example, the value of the normalized leakage current of the capacitor of the present invention is about 1 μA / μF in some embodiments.^*Less than V, about 0.5 μA / μF in some embodiments^*Less than V, and in some embodiments 0.1 μA / μF^*Less than V, where μA is microamperes, μF^*V is the product of capacitance and rated voltage. Such normalized leakage current values can be maintained even after a substantial amount of time at high temperatures. For example, values range from about -55 ° C to about 250 ° C, in some embodiments from about 0 ° C to about 225 ° C, and in some embodiments from about 10 ° C to about 225 ° C. At temperature, about 100 hours or longer, in some embodiments about 300 to about 3000 hours, and in some embodiments about 400 to about 2500 hours (eg, 500 hours, 600 hours, 700). It can be maintained for hours, 800 hours, 900 hours, 1000 hours, 1100 hours, 1200 hours, or 2000 hours).

The present invention can be better understood with reference to the following examples.

<u style="single">Procedure of test</u> Equivalent series resistance (ESR) Equivalent series resistance can be measured using a "Keithley 3330 Precision LCZ" meter with a Kelvin lead using a 2.2 volt DC bias and a 0.5 volt interpeak peak sinusoidal signal. The operating frequency was 100 kHz and the temperature was room temperature.

Dry and wet capacitance Capacitance was measured using a "Keithley 3330 Precision LCZ" meter with a Kelvin lead using a 2.2 volt DC bias and a 0.5 volt interpeak peak sinusoidal signal. The operating frequency was 120 kHz and the temperature was room temperature. "Dry capacitance" means the capacitance of the part after the addition of solid electrolyte, graphite, and silver layer, while "wet capacitance" means the formation of a dielectric measured with 17% sulfuric acid relative to a 1mF tantalum cathode. It means the capacitance of the rear part.

V / I characteristics The V / I test was performed at that temperature. The test was performed by charging individual capacitors with a 100 ohm resistor (charging gradient dU / dt = 100). The starting voltage was 5V and the ending voltage was 30V (the voltage step was 1V per minute). Voltage and current values were recorded.

<p num="0069"> Anode samples were formed using 70,000 μF V / g tantalum powder. Each anode sample is embedded in tantalum wire sintered at 1280 ° C and 6.8 g / cm.³Was pressed to a density of. The resulting pellet had a size of 1.80 x 1.20 x 2.40 mm. The pellet was anodized to 14.4 V in a water / phosphate electrolyte with a conductivity of 8.6 mS at a temperature of 85 ° C to form a dielectric layer. The pellet was further anodized to 60 V in water / boric acid / disodium tetraborate having a conductivity of 2.0 mS at a temperature of 30 ° C. for 25 seconds to form a thinner oxide layer deposited on the outside. The conductive polymer coating is then immersed in a dispersed poly (3,4-ethylenedioxythiophene) (Clevious® K, HC Starck) with a solid content of 1.1% and a viscosity of 20 mPa.s. Formed by doing. Upon coating, these portions were dried at 125 ° C for 20 minutes. This process was repeated 10 times. These moieties were then immersed in dispersed poly (3,4-ethylenedioxythiophene) (Clevious® K, HC Starck) with a solid content of 2% and a viscosity of 20 mPa.s. Upon coating, these portions were dried at 125 ° C for 20 minutes. This process was not repeated. These moieties were then immersed in dispersed poly (3,4-ethylenedioxythiophene) (Clevious® K, HC Starck) with a solid content of 2% and a viscosity of 160 mPa.s. Upon coating, these portions were dried at 125 ° C for 20 minutes. This process was repeated 8 times. These portions were then dipped in a graphite dispersant and dried. Finally, these portions were immersed in a silver dispersant and dried. Multiple parts (200) of a 150μF / 6.3V capacitor were made in this way.</p>

<p num="0070"> Capacitors were formed as described in Example 1 except that different conductive polymer coatings were used. The conductive polymer coating is made by immersing the anode in dispersed poly (3,4-ethylenedioxythiophene) (Clevious® K, HC Starck) with a solid content of 1.1% and a viscosity of 20 mPa.s. Been formed. Upon coating, these portions were dried at 125 ° C for 20 minutes. This process was repeated 10 times. These moieties then have a solid content of 2% and a viscosity of 20 mPa.s and a molecular weight of 1228 ("Sigma"). Aldrich®) Dispersed poly (3,4-ethylenedioxythiophene) with an additional 20% solid content of polyoxyethylene sorbitan monolaurate (Tween® 20) (Clevious® Immersed in K, HC Starck). Upon coating, these portions were dried at 125 ° C for 20 minutes. This process was not repeated. These moieties were then immersed in dispersed poly (3,4-ethylenedioxythiophene) (Clevious® K, HC Starck) with a solid content of 2% and a viscosity of 160 mPa.s. Upon coating, these portions were dried at 125 ° C for 20 minutes. This process was repeated 8 times. These portions were then dipped in a graphite dispersant and dried. Finally, these portions were immersed in a silver dispersant and dried. Multiple parts (200) of a 150μF / 6.3V capacitor were made in this way.</p><p num="0071"> The final capacitors of Examples 1-2 were then tested for electrical performance prior to the assembly process. The average results of capacitance, Df, and ESR are explained in Table 1 as follows. The wet capacitance was 145.0 μF in both examples.</p><p num="0072">(table 1)<img id="000006" he="31" wi="159" file="JP6317552B2_D0001.tif" img-format="tif" img-content="drawing" /></p><p num="0073"> As shown, each portion of Example 2 containing the nonionic surfactant had a higher dry / wet capacitance value than each portion of Example 1 containing no surfactant.</p><p num="0074"> The final capacitors of Examples 1-2 were then also tested for V / I characteristics prior to the assembly process. The average result of current at milliamperes at a given voltage is explained in Table 2 as follows.</p><p num="0075">(Table 2)<img id="000007" he="36" wi="159" file="JP6317552B2_D0001.tif" img-format="tif" img-content="drawing" /></p><p num="0076"> These and other modifications and modifications of the present invention can be carried out by those skilled in the art without departing from the spirit and scope of the present invention. Furthermore, it should be understood that aspects of the various embodiments may be compatible, both in whole and in part. Further, one of ordinary skill in the art will recognize that the above description is merely exemplary and is not intended to limit the invention further described in the claims.</p>

16 Anode lead 30 Electrolytic capacitors 33 Capacitor elements 62 Anode termination 72 Cathode termination