Lead frame including discontinuous surface coating for improved capacitor lifespan

Abstract

The present invention provides a capacitor and a method for forming a capacitor. [Solution] The capacitor includes a first capacitive couple comprising a first dielectric on a first anode and a first cathode on the first dielectric. The first anode and the first cathode are connected to a lead frame which includes a discontinuous surface coating comprising a contact region and a discontinuous region. At least one of the first anode or the first cathode makes electrical contact in the contact region. The casing is in contact with the lead frame in the discontinuous region.

Description

[Technical Field]

[0001] The present invention relates to a solid electrolyte surface mount capacitor with improved lifespan. More specifically, the present invention relates to a solid electrolyte capacitor comprising an anode and a cathode assembled with a lead frame including a discontinuous surface coating, wherein the discontinuous surface coating mitigates the separation of the casing (encapsulant) from the lead frame. [Background technology]

[0002] Electronic capacitors are well-known and widely used in the art. A great many capacitor designs exist. This invention particularly relates to a solid electrolyte capacitor in which a conductive cathode layer, preferably a conductive polymer cathode layer, is formed on the surface of a dielectric material. Degeneration of the conductive polymer and other components of a solid electrolyte capacitor due to oxygen and moisture at high temperatures is one of the main factors limiting the lifespan of such capacitors, thus restricting their use in high-temperature applications. This invention is particularly useful in all situations where a solid electrolyte capacitor may experience high-temperature periods, whether temporary or persistent.

[0003] A multiple anode capacitor containing multiple capacitive elements is schematically illustrated in Figure 1 to better illustrate the problem that the present invention solves. Each capacitive element includes an anode 10 in the form of a conductive sheet or foil. A dielectric, not illustrated, surrounds at least part or all of the anode. A conductive cathode 12 surrounds at least part of the dielectric, and it can be seen that the cathode and anode are separated by the dielectric and there is no direct physical contact between them. The anode and cathode form a capacitive couple with the dielectric in between, as understood by those skilled in the art. The anodes are electrically coupled to each other and to the anode leads 14. The cathodes are also electrically in contact with each other and, as a whole, with the cathode leads 24. The anode leads and cathode leads are referred to herein as the lead frame, and the terms anode and cathode are used herein for clarity, but it should be understood that their electrical functions may be reversed. The casing 22 surrounds the capacitor except for the ends of the cathode leads and anode leads of the lead frame.

[0004] Figure 1 illustrates a capacitor 8 with a failure mode displayed. As those skilled in the art will see, a gap 18 is created between at least a portion of the casing 22 and the anode lead 14. The gap 18 between the casing and the anode lead provides a point of penetration for environmental components such as oxygen and water, which have detrimental effects on the capacitor's functionality and lifespan, especially at high temperatures. Such a gap 18 may also occur between the casing 22 and the cathode lead 24. [Overview of the project] [Problems that the invention aims to solve]

[0005] Many engineers have sought ways to improve the adhesion between the casing and the lead frame. Various compositions have been developed to improve this adhesion. Nevertheless, it is surprising that the problem persists. A commonly used approach is to mechanically or chemically etch the lead frame to increase its surface area, which is expected to improve the mechanical locking between the casing and the lead frame. While mechanical locking can be beneficial to some extent, it has become clear that it is not sufficient.

[0006] Through thorough research, the inventors discovered a previously unknown failure mode. Referring to Figure 2a, the lead frame shown as the anode lead typically contains a tin-like surface coating 20. While not limited to theory, we assume that the temperature of the lead frame rises when the capacitor is exposed to heat, such as during surface mounting. With sufficient time and heat applied, the surface coating 20 begins to flow or be absorbed in the direction of the arrow, and the surface coating is absorbed from beneath the casing 22. As illustrated in Figure 2b, once sufficient absorption of the surface coating occurs, the space between the casing and the lead frame creates a gap 18, such a gap provides a point of penetration for environmental components. Integrity degradation in such cases can also occur on the cathode side.

[0007] The present invention provides an improved capacitor with improved case integrity between the casing and the anode or cathode lead. [Means for solving the problem]

[0008] This specification provides improved capacitors, particularly surface-mount solid electrolyte capacitors, that improve the lifespan of the capacitor by mitigating the degradation of case integrity due to heat between the casing and the anode or cathode leads.

[0009] A particular advantage of the present invention is that it can provide a surface-mounted discrete capacitor that is more durable against thermal degradation such as thermal fluctuations that occur during reflow, surface mounting, or normal use.

[0010] A particular feature of the present invention is the thermal stability achieved by the present invention.

[0011] Such advantages and other advantages are provided, as will be appreciated, by a capacitor including a first capacitive couple including a first dielectric on a first anode and a first cathode on the first dielectric. The first anode and the first cathode are connected to a lead frame including a discontinuous surface coating including a contact region and a discontinuous region. At least one of the first anode or the first cathode makes electrical contact in the contact region. The casing contacts the lead frame in the discontinuous region.

[0012] Still other embodiments include forming a first capacitive couple including a first dielectric on a first anode and a first cathode on the first dielectric; providing a lead frame including a discontinuous surface coating including a contact region and a discontinuous region; electrically connecting the first anode or the first cathode to the contact region; and encapsulating the capacitive couple with a casing, provided in a method of forming a capacitor.

Brief Description of the Drawings

[0013] [Figure 1] A schematic cross-sectional view of a prior art capacitor. [Figure 2] A schematic partial view of a prior art capacitor. [Figure 3] A schematic cross-sectional view of an embodiment of the present invention. [Figure 4] A schematic partial cross-sectional view of an embodiment of the present invention. [Figure 5] A flowchart of an embodiment of the present invention. [Figure 6] This is a schematic cross-sectional view of one embodiment of the present invention. [Modes for carrying out the invention]

[0014] The present invention relates to an improved capacitor, preferably an improved surface-mount solid electrolyte capacitor. More specifically, the present invention relates to an improved capacitor including a lead frame, wherein a discontinuous surface coating is formed on the anode lead and / or cathode lead of the lead frame, and the discontinuous surface coating suppresses the movement of the surface coating between the lead frame and the casing.

[0015] The present invention is described with reference to drawings, which are an essential part of the specification provided for clarity of the invention, but are not limited thereto. Similar elements throughout the various drawings are indicated by corresponding numbers.

[0016] An embodiment of the present invention will be described with reference to Figure 3. Figure 3 schematically illustrates an embodiment of the present invention in the form of a cross-sectional view.

[0017] In Figure 3, the capacitor 90 includes a capacitive element comprising a conductive, preferably porous sheet or foil-like, anode 10. A dielectric, not illustrated, surrounds at least a portion, preferably the entire anode. A conductive cathode 12 surrounds at least a portion of the dielectric, and it should be understood that the cathode and anode are separated by the dielectric and do not directly contact each other. As will be understood by those skilled in the art, the anode and cathode form an electrostatic couple with the dielectric in between. The capacitive couple is not particularly limited herein. The anodes are electrically and mechanically coupled to each other at junction regions 25 and to the surface coating 106 of discontinuous anode leads 100 at contact sites further described herein. The cathodes are electrically in contact with each other and to cathode leads 24, which include an optional but preferred discontinuous cathode surface coating 28, including a discontinuous region 108, where the discontinuous region lacks the surface coating, and the function of the surface coating will be further clarified in a subsequent description. The casing 22 encloses at least a portion, preferably the entirety, of the capacitive couple and the capacitor, except for the terminations of the cathode and anode leads that form the lead frame. It will be understood that the anode and cathode leads are collectively referred to as the lead frame 107. In Figure 3, the anode and cathode leads are illustrated differently from each other for discussion and clarity, and additional notes are provided. In one embodiment, the anode and cathode leads may be configured as separate parts and collectively form the lead frame, and may not be separated from each other. When the anode and cathode leads are not separated, the discontinuous surface coatings of each lead may be substantially identical, and the size of the discontinuous region may be similar. As illustrated in Figure 3, it is preferable that at least one, preferably both, of the anode or cathode leads of the lead frame include a plurality of surface perturbations to increase the surface area. It is preferable that the surface perturbations extend at least the length of the discontinuous region. The surface perturbations may be formed without being limited to repeating patterns or arbitrary shapes. In a particularly preferred embodiment, the surface perturbation portion has a dimple shape, which is a substantially circular depression with an average diameter of 5 μm to 500 μm.In other embodiments, surface perturbations can be formed to an average depth of 0.5 μm to 20 μm by laser ablation or chemical etching.

[0018] In Figure 6, the capacitor 200 includes a capacitive element comprising an anode 210 in compressed powder form, which is preferably a porous single entity formed by compressing powder. An anode wire 218 extends from the anode. The anode wire may preferably be embedded in the powder before compression, or it may be attached to the surface of the anode after compression by welding or the like. A dielectric 212 surrounds at least a portion of the anode, preferably the entire anode. A conductive cathode 214 surrounds at least a portion of the dielectric, and it should be understood that the cathode and anode are separated by the dielectric and do not come into direct contact. As is understood in the art, an optional but preferred adhesive layer 216 is provided to improve the adhesion between the cathode and the cathode lead. As will be understood by those skilled in the art, the anode and cathode form a capacitive couple with the dielectric in between. A discontinuous anode lead is in electrical contact with the anode wire. The cathode electrically contacts the cathode lead 24, which includes an optional but preferred discontinuous cathode surface coating that includes a discontinuous region, the discontinuous region lacking a surface coating having a function as described separately herein. The casing 22 encloses at least a portion, preferably the whole, of the capacitive couple and the capacitor, except for the terminations of the cathode and anode leads that form the lead frame. It will be understood that the anode and cathode leads are collectively referred to as the lead frame 107. In Figure 6, the anode and cathode leads are illustrated and annotated separately from each other for discussion and clarity. In one embodiment, the anode and cathode leads may be configured as separate parts and collectively form the lead frame and may not be separated from each other. When the anode and cathode leads are not separated, the discontinuous surface coatings of each lead may be substantially identical, and the dimensions of the discontinuous region may be similar. As illustrated in Figure 6, it is preferable that at least one, preferably both, of the anode or cathode leads of the lead frame include a plurality of surface perturbations to increase the surface area as described herein.

[0019] For clarity, a schematic partial cross-sectional view, shown in a dotted box, is illustrated in Figure 4, through which the portion of the discontinuous anode lead in the lead frame can be more easily understood. The discontinuous anode lead 100 includes a metal base 102. Preferably, a continuous, optional, but preferred, primary metal layer 104 is present on the discontinuous anode lead. The primary metal layer is provided to improve adhesion between the metal base and subsequent layers and to protect the metal base from corrosion and oxidation. A discontinuous surface layer 106 is present on the metal base, with or without the primary metal layer. The discontinuous surface layer includes discontinuous regions 108 where the surface coating of the discontinuous surface layer 106 is absent, and in the portion of the discontinuous region, the layer directly beneath it is exposed. The discontinuous region begins near an adhesion point 110, which is the end of the overlap or contact area of ​​the anode and anode lead, and extends away from the adhesion point and away from the overlap of the anode and anode lead.

[0020] The discontinuous region present in either the anode lead or the cathode lead of the lead frame, preferably in both the anode and cathode leads, prevents absorption or flow of the discontinuous surface layer of the lead frame, thereby preventing the formation of a gap between the lead frame and the casing.

[0021] An embodiment of the present invention is described with reference to Figure 5, and a method for forming the present invention is provided in the form of a flowchart. In Figure 5, an anode is provided at 200, and a dielectric is formed on the anode at 202. A cathode is formed on the dielectric at 204, covering a portion of the anode to form a capacitive couple. The formation of the capacitive couple can be repeated "A" times. At 206, an anode lead and a cathode lead are provided, optionally etched at 208, and then a discontinuous region is formed in the surface coating at 210. At 212, the portion of the multiple anode not covered by the cathode is joined to the anode lead through the already formed discontinuous region. At 214, the cathode lead is electrically coupled to the cathodes of each capacitive couple to form a capacitor. As will be understood by those skilled in the art, the anode lead and the cathode lead may be components of a common lead frame, and therefore steps (212 and 214) can be performed substantially simultaneously. At 216, the capacitor is encased in resin.

[0022] The method for forming discontinuous regions is not particularly limited herein. Discontinuous regions may be formed by mechanical serration, ablation, especially laser ablation, chemical etching, or by forming discontinuous regions using masking techniques, including vapor deposition of surface coatings.

[0023] The junction region is the area in the stack where anodes are electrically coupled to each other. The contact region is the area where anodes are electrically coupled to the anode closest to the anode lead, or to both sides thereof. The junction region must be the same as or longer than the contact region to provide the maximum electrical contact area.

[0024] The length of the discontinuous region is preferably at least 2 micrometers, more preferably at least 4 to 40 micrometers, and even more preferably 20 micrometers or less. The length of the discontinuous region extending beyond the point where the lead frame exits the casing does not significantly increase the advantages.

[0025] In the drawings, the capacitor is illustrated with four capacitive couples for clarity. In most embodiments, the capacitor preferably has at least one second capacitive couple, and more preferably at least 2 to about 40 capacitive couples. The present invention can be embodied with a very large number of capacitive couples. When there are more than about 40 capacitive couples, the size of the capacitor may not be convenient for surface mount applications, and difficulties may arise from a manufacturing standpoint. About 2 to 20 capacitive couples in a single capacitor is optimal. The anode lead is centrally located between adjacent capacitive couples. The anode lead may be off-center due to packaging design considerations. This is an illustrative example. The number of capacitive couples attached to either side of the anode lead is not limited, and there may be at least one capacitive couple on one side, all capacitive couples on the same side, and any other capacitive couples located on the opposite side.

[0026] The anode is a conductor, most preferably a porous metallic conductor in the form of foil or compressed and sintered powder. While not limited thereto, valve metal or conductive oxides of valve metal are particularly suitable for demonstrating the present invention. More preferably, the anode comprises valve metal, a mixture of valve metals, an alloy, or a conductive oxide, the valve metal preferably selected from Al, W, Ta, Nb, Ti, Zr, and Hf. The anode is preferably porous and in the form of foil or compressed and sintered powder. More preferably, the anode comprises aluminum or tungsten. Anodes in the form of etched foil or compressed and sintered powder with a high surface area are preferred.

[0027] Etching of the anode, anode lead, or cathode lead can be carried out by chemical etching or by forming a surface perturbation through mechanical perturbation. Etching is preferably carried out by immersing the anode in at least one etching bath. Optionally, an electrical bias can be applied during etching. A variety of etching baths are known in the art, and the methods used herein for etching the anode, anode lead, or cathode lead are not limited.

[0028] A particularly preferred anode material for compressed powder anodes is a metal, and a particularly preferred metal is valve metal or a conductive oxide of valve metal. Particularly preferred compressed powder anodes include materials selected from the group consisting of niobium, aluminum, tungsten, and NbO. Tantalum is the most preferred anode material. High charge density powders exceeding 50,000 CV / g are preferred. Particularly preferred powders have a charge density exceeding about 100,000 CV / g, preferably about 200,000 CV / g, more preferably about 250,000 CV / g, and up to about 350,000 CV / g.

[0029] The anode wire is either embedded in or attached to the anode, but an embedded anode wire is preferred. The constituent material of the anode wire is not particularly limited, but for ease of manufacturing, the anode wire is preferably made of the same material as the anode.

[0030] A dielectric is formed on the surface of the anode, and it is preferable to increase the surface area by etching or roughening the surface of the anode. The dielectric is a nonconductive layer, which is not particularly limited herein and is consistent with those widely used in the art. The dielectric may be a metal oxide or a ceramic material. For ease of formation and use, the dielectric is particularly preferably an oxide of the metal used for the anode. The dielectric layer is preferably an oxide of the valve metal, as further described herein. The dielectric is preferably formed by immersing the anode in an electrolyte solution and applying a positive voltage to the anode. The electrolyte for oxide formation is not particularly limited herein, but exemplary materials may include ethylene glycol; a solution of polyethylene glycol dimethyl ether dissolved in water, as described in U.S. Patent No. 5,716,511; alkanolamines and phosphoric acid, as described in U.S. Patent No. 6,480,371; a solution of phosphoric acid in a polar aprotic solvent, as described in British Patent No. GB ​​2,168,383 and U.S. Patent No. 5,185,075; U.S. Patent No. 6,475,368 teaches anodizing using alpha hydroxy acids, and U.S. Patent No. 6,475,368 teaches reel aluminum anodizing or a similar method. As an electrolyte for forming a dielectric on the anode, aqueous solutions of dicarboxylic acids, such as ammonium adipate, are also known. Other materials such as phosphates and citrates may be included in the dielectric to impart thermal stability, chemical or water resistance to the dielectric layer.

[0031] The cathode layer is preferably a conductive layer comprising a conductive polymer such as polythiophene, polyaniline, polypyrrole or derivatives thereof; manganese dioxide, lead oxide or combinations thereof. Intrinsically conductive polymers are most preferred. The polymer may be applied by any technique commonly used to form a layer on a capacitor, comprising dipping, spraying, and allowing polymerization to proceed for a set time, and then terminating the polymerization by washing. The polymer may also be applied by electrochemical precipitation methods, as is widely known in the art.

[0032] The cathode may be coated as a polymer layer, or the polymer may be formed by coating an oxidizing agent and a monomer in situ, preferably by sequential dipping with a wetting agent, preferably optionally, or by pressure changes, to improve the movement of the monomer and / or oxidizing agent into the anode's interstitial region. In a particularly preferred embodiment, each anode is collectively or individually immersed in the oxidizing agent so that the oxidizing agent is deposited on the dielectric surface, and then immersed in a monomer solution so that the monomer moves into the interstitial space and is polymerized by the oxidizing agent. The monomer may be coated first, and then the oxidizing agent may be added. It is preferable to repeatedly coat the monomer and oxidizing agent alternately so that the interstitial space is filled to the maximum extent. Polymer coating is considered either before monomer coating or after the polymer has been formed from the monomer. As is known in the art, it is preferable to carry out the reformation step after polymer formation.

[0033] Particularly preferred conductive polymers are exemplified by the following chemical formula A: JPEG2026053306000002.jpg3847 Here, R 1 and R 2 These are independently linear or branched C1-C 16represents alkyl, C2-C18 alkoxyalkyl, C3-C8 cycloalkyl, phenyl or benzyl, which are unsubstituted or substituted by C1-C6 alkyl, C1-C6 alkoxy, halogen or OR 3 or unsubstituted or substituted; or R 1 and R 2 are both linear C1-C6 alkylene, and are unsubstituted or substituted by C1-C6 alkyl, C1-C6 alkoxy, halogen, C3-C8 cycloalkyl, phenyl, benzyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, halophenyl, C1-C4 alkylbenzyl, C1-C4 alkoxybenzyl or halobenzyl, a 5-, 6- or 7-membered heterocyclic structure containing two oxygen elements R 3 is hydrogen, linear or branched C1-C 16 alkyl or C2-C 18 alkoxyalkyl, C3-C8 cycloalkyl, phenyl or benzyl, which are unsubstituted or substituted by C1-C6 alkyl; X is S; and n is a polymer in which the compound of formula A has a variety of molecular weights; generally, n is an integer sufficient to achieve an average molecular weight of 2 to about 500,000

[0034] R in formula A 1 and R 2 are preferably selected to prevent polymerization at the β-site of the ring because polymerization at only the α-site is most preferred. R 1 and R 2 are preferably not hydrogen, and more preferably R 1 and R 2 are this preferred α-directing body with an ether bond rather than an alkyl bond. To avoid steric interference, R 1 and R 2 are most preferably small

[0035] In a particularly preferred embodiment, R in formula A 1 and R 2 are both -O-(CHR4 ) m -O- represents -O-, where m is an integer from 1 to 5, most preferably 2; each R 4 Hydrogen, linear or branched C1-C 18 Alkyl radicals, C5~C 12 Cycloalkyl radical, C6~C 14 Aryl radicals, C7~C 18 Functional groups independently selected from aralkyl radicals or C1-C4 hydroxyalkyl radicals, which can optionally provide self-doping functionality, particularly carboxylic acids, hydroxyls, amines, substituted amines, alkenes, acrylates, thiols, alkynes, azides, sulfates, hydrochloric acid, sulfuric acid, imides, amides, epoxys, anhydrides, silanes, and phosphates; which may be substituted with hydroxyl radicals or R 4 ha-(CHR 5 ) a -R 16 ;-O(CHR 5 ) a R 16 -CH2O(CHR 5 ) a R 16 -CH2O(CH2CHR 5 O) a R 16 Selected from, or R 4 This is a functional group selected from the group consisting of hydroxyl, carboxyl, amine, epoxy, amide, imide, anhydride, hydroxymethyl, alkene, thiol, alkyne, azide, sulfate, benzenesulfonic acid sulfate, SO3M, anhydride, silane, acrylate, and phosphate; R 5 R is an alkyl chain composed of H or 1 to 5 carbon atoms, which is optionally substituted with a functional group selected from carboxylic acids, hydroxyls, amines, alkenes, thiols, alkynes, azides, epoxys, acrylates, and anhydrides. 16a is an alkyl chain composed of H, -SO3M, or 1 to 5 carbon atoms, which is optionally substituted with a functional group selected from carboxylic acids, hydroxyls, amines, substituted amines, alkenes, thiols, alkynes, azides, amides, imides, sulfates, SO3M, amides, epoxys, anhydrides, silanes, acrylates, and phosphates. a is an integer from 0 to 10. M is H or preferably a cation selected from ammonia, sodium, or potassium.

[0036] A particularly preferred polymer is 3,4-polyethylenedioxythiophene (PEDOT), which is produced from the monomer 3,4-ethylenedioxythiophene (EDOT).

[0037] Particularly preferred conductive polymers include poly(3,4-ethylenedioxythiophene), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-butane-sulfonic acid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-propane-sulfonic acid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-methyl-1-propane-sulfonic acid, salt), poly( 4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy alcohol, poly(N-methylpyrrole), poly(3-methylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly(3-carboxypyrrole), poly(3-methyl-4-carboxypyrrole), poly(3-methyl-4-carboxyethylpyrrole), poly(3-methyl-4-carboxybutylpyrrole) Poly(3-hydroxypyrrole), poly(3-methoxypyrrole), polythiophene, poly(3-methylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-tesylthiophene), poly(3-todecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene), poly(3-hydroxythiophene), poly(3-methoxythiophene) ), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-tesiloxythiophene), poly(3-todecyloxythiophene), poly(3-octadecyloxythiophene), poly(3,4-dihydroxythiophene), poly(3,4-dimethoxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,This includes 4-butenedioxythiophene, poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3-methyl-4-carboxybutylthiophene), polyaniline, poly(2-methylaniline), poly(3-isobutylaniline), poly(2-aniline sulfonic acid), poly(3-aniline sulfonic acid), etc.

[0038] Particularly suitable polymers or copolymers are selected from the group consisting of poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-butane-sulfonic acid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-methyl-1-propane-sulfonic acid, salt), poly(N-methylpyrrole), poly(3-methylthiophene), poly(3-methoxythiophene), and poly(3,4-ethylenedioxythiophene). Preferred polyanions are described in U.S. Patent No. 10,340,091, with polystyrene sulfonic acid being particularly preferred.

[0039] When using a manganese dioxide layer, it is preferable to obtain the manganese dioxide layer by immersing the stacked anode in an aqueous manganese nitrate solution. The manganese oxide is formed by thermal decomposition of the nitrate at a temperature of 200-350°C, either in a dry or vapor atmosphere. The anode may be treated multiple times to ensure optimal coating.

[0040] As is typically applied in the art, a variety of doping agents can be introduced into the polymer during the polymerization process or post-treatment. Doping agents can be derived from a variety of acids or salts, including aromatic sulfonic acids, aromatic polysulfonic acids, organic sulfonic acids with hydroxyl groups, organic sulfonic acids with carboxyhydroxyl groups, alicyclic sulfonic acids, benzoquinone sulfonic acids, benzenedisulfonic acids, sulfosalicylic acids, sulfoisophthalic acids, camphor sulfonic acids, benzoquinone sulfonic acids, dodecylbenzenesulfonic acids, and toluenesulfonic acids. Other suitable doping agents include sulfoquinones, anthracene monosulfonic acids, substituted naphthalene monosulfonic acids, substituted benzenesulfonic acids, or heterocyclic sulfonic acids.

[0041] The conductive polymer layer may contain binders and cross-bonders as needed. Suitable materials include poly(vinyl acetate), polycarbonate, poly(vinyl butyrate), polyacrylate, polymethacrylate, polystyrene, polyacrylonitrile, poly(vinyl chloride), polybutadiene, polyisoprene, polyether, polyester, silicone, and pyrrole / acrylate, vinyl acetate / acrylate and ethylene / vinyl acetate copolymers, and epoxy substrate polymers.

[0042] It is preferable to include a doping agent in the polymer. The doping agent may be applied separately or contained in the oxidizing agent solution. Doping agents are widely known in the art and are not limited herein.

[0043] The anode is preferably fixed to the anode lead by welding. The metal base of the anode lead is a conductor, and metal conductors including copper, iron, nickel, chromium, and alloys are most preferred. Materials particularly suitable for use as a metal base include alloy 194, alloy 752, alloy 42, and stainless steel. The anode lead is preferably plated with another metal to improve weldability to circuit traces. In a particularly preferred embodiment, an optional primary metal layer is plated on the anode lead prior to plating of a surface coating which ultimately forms a discontinuous surface coating. Materials particularly suitable for demonstration of the present invention include, but are not limited to, valve metal or conductive oxides of valve metal.

[0044] The primary metal layer preferably contains metals including nickel, iron, chromium, copper, and alloys thereof.

[0045] Particularly preferred discontinuous surface coatings include tin or alloys of tin with other metals, such as Pb. The discontinuous surface coating is a solderable layer. Particularly preferred discontinuous surface coatings include any metal or metal alloy with a melting point of less than 260°C.

[0046] In the drawing, the cathode and anode leads of the lead frame are exemplified as being located between adjacent capacitive couples and centrally positioned. This is for illustrative purposes only. There is no limit to the number of capacitive couples attached to either side of the lead frame; it can range from one capacitive couple to all capacitive couples.

[0047] The resin used for the casing is not particularly limited herein and is used under conditions that the resin is understood to be electrically insulating. All resins typically used in the art are suitable for demonstration of the present invention.

[0048] As is widely known in the art, it is difficult to bond adjacent polymer cathodes to each other or to cathode leads. To improve connectivity between adjacent cathodes and cathode leads, it is preferable to provide an adhesive layer on the conductive polymer layer. The adhesive layer typically includes a metal-containing layer, such as a carbon-containing layer on the conductive polymer layer and a silver-containing layer on the carbon layer. Such layers are formed by dipping, coating, painting, electroplating, or deposition such as vapor deposition.

[0049] The present invention has been described by preferred embodiments, but is not limited thereto. Those skilled in the art can implement additional embodiments as described and expressed in the claims appended herein.

Claims

1. A first capacitive couple comprising a first dielectric on a first anode and a first cathode on the first dielectric; A lead frame including a discontinuous surface coating that includes contact areas and discontinuous areas; and Casing (encapsulant) in contact with the discontinuous region. Includes, A capacitor in which at least one of the first anode or the first cathode makes electrical contact in the contact region.

2. The capacitor according to claim 1, wherein the first anode makes electrical contact with the contact region.

3. The capacitor according to claim 1, wherein the first cathode makes electrical contact with the contact region.

4. The capacitor according to claim 1, wherein the lead frame includes a surface perturbation portion.

5. The capacitor according to claim 4, wherein the surface perturbation portion is located in the discontinuous region.

6. The capacitor according to claim 1, comprising a second capacitive couple including a second anode and a second cathode, wherein at least one of the second anode or the second cathode is in electrical contact with a second contact region.

7. The capacitor according to claim 6, comprising up to 40 capacitive couples.

8. The capacitor according to claim 7, comprising up to 2 to 20 capacitive couples.

9. The capacitor according to claim 1, wherein the discontinuous region extends from the attachment point, which is the termination point of the contact region, in a direction away from the contact region.

10. The capacitor according to claim 1, wherein the discontinuous region extends for a length of 2 micrometers or more and 40 micrometers or less.

11. The capacitor according to claim 1, wherein the discontinuous surface coating comprises any metal or metal alloy having a melting point of less than 260°C.

12. The capacitor according to claim 1, wherein the lead frame includes a metal base.

13. The capacitor according to claim 12, wherein the metal base includes copper, ions, nickel, chromium, and alloys thereof.

14. The capacitor according to claim 13, wherein the metal base includes alloy 194, alloy 752, alloy 42, and stainless steel.

15. The capacitor according to claim 1, wherein the anode lead includes a primary metal layer on which the discontinuous surface coating is formed.

16. The capacitor according to claim 15, wherein the primary metal layer comprises nickel, iron, chromium, copper, and alloys thereof.

17. The capacitor according to claim 15, wherein the discontinuous surface coating comprises any metal or metal alloy having a melting point of less than 260°C.

18. The capacitor according to claim 15, wherein the discontinuous surface coating comprises tin or a tin alloy.

19. The capacitor according to claim 18, wherein the tin alloy contains lead.

20. The capacitor according to claim 1, wherein the anode includes a metal.

21. The capacitor according to claim 20, wherein the anode includes valve metal.

22. The capacitor according to claim 21, wherein the anode is preferably selected from the group consisting of Al, W, Ta, Nb, Ti, Zr, and Hf.

23. The capacitor according to claim 22, wherein the anode comprises aluminum.

24. The capacitor according to claim 22, wherein the anode includes tantalum.

25. The capacitor according to claim 20, wherein the anode is a foil.

26. The capacitor according to claim 20, wherein the anode is etched.

27. The capacitor according to claim 20, wherein the anode comprises sintered compressed powder.

28. The capacitor according to claim 1, wherein the cathode comprises a conductive polymer or manganese dioxide.

29. The capacitor according to claim 28, wherein the conductive polymer is selected from the group consisting of polythiophene, polyaniline, polypyrrole and derivatives thereof.

30. The conductive polymer is defined by the following chemical formula A: Here, R １ and R ２ each independently represents a linear or branched C １ -C １６ alkyl, C ２ -C １８ alkoxyalkyl, C ３ -C ８ cycloalkyl, phenyl or benzyl, which are unsubstituted or substituted by C １ -C ６ alkyl, C １ -C ６ alkoxy, halogen or OR ３ and are either unsubstituted or substituted; or R １ and R ２ Both are linear C １ -C ６ It is alkylene, C １ -C ６ Alkyl, C １ -C ６ Alkoxy, halogen, C ３ -C ８ Cycloalkyl, phenyl, benzyl, C １ -C ４ Alkylphenyl, C １ -C ４ Alkoxyphenyls, halophenyls, C １ -C ４ Alkylbenzyl, C １ -C ４ Alkoxybenzyl or halobenzyl, unsubstituted or substituted 5-, 6-, or 7-membered heterocyclic structures containing two oxygen elements; R ３ is hydrogen, linear or branched C １ -C １６ Alkyl or C ２ -C １８ Alkoxyalkyl, C ３ -C ８ These represent cycloalkyl, phenyl, or benzyl, and these are C １ -C ６ Alkyl substitution is either not substituted or is substituted; X is S; and n is an integer number sufficient to achieve an average molecular weight of 2 to approximately 500,000. The capacitor according to claim 29.

31. The conductive polymer is 3,4-polyethylenedioxythiophene, the capacitor according to claim 29.

32. A step of forming a first capacitive couple including a first dielectric on a first anode and a first cathode on the first dielectric; A step of providing a lead frame including a discontinuous surface coating that includes contact areas and discontinuous areas; The step of electrically connecting the first anode or the first cathode to the contact area; and The step of encapsulating the aforementioned capacitive couple in a casing. Includes, A method for forming a capacitor, wherein the casing is in contact with the lead frame in the discontinuous region.

33. The capacitor formation method according to claim 32, further comprising the step of electrically connecting the first anode to the contact region.

34. The capacitor formation method according to claim 32, further comprising the step of electrically connecting the first cathode to the contact region.

35. The capacitor formation method according to claim 32, wherein the lead frame includes a surface perturbation portion.

36. The capacitor formation method according to claim 35, wherein the surface perturbation portion is located in the discontinuous region.

37. A method for forming a capacitor according to claim 32, further comprising the steps of forming a second capacitive couple having a second anode and electrically connecting the second anode to the first anode in a junction region.

38. A method for forming a capacitor according to claim 37, comprising the step of forming up to 40 capacitive couples.

39. A method for forming a capacitor according to claim 38, comprising the step of forming a maximum of 2 to 20 capacitive couples.

40. The capacitor forming method according to claim 32, wherein the discontinuous region extends from the attachment point, which is the termination point of the contact region, in a direction away from the contact region.

41. The capacitor formation method according to claim 32, wherein the discontinuous region extends for a length of 2 micrometers or more and 40 micrometers or less.

42. The capacitor forming method according to claim 32, wherein the discontinuous surface coating comprises any metal or metal alloy having a melting point of less than 260°C.

43. The capacitor formation method according to claim 32, wherein the discontinuous surface coating comprises tin or a tin alloy.

44. The capacitor formation method according to claim 43, wherein the tin alloy contains lead.

45. The capacitor formation method according to claim 32, wherein the anode lead includes a metal base.

46. The method for forming a capacitor according to claim 45, wherein the metal base includes copper, ions, nickel, chromium, and alloys thereof.

47. The capacitor forming method according to claim 46, wherein the metal base includes alloy 194, alloy 752, alloy 42, and stainless steel.

48. The capacitor formation method according to claim 32, wherein the anode lead includes a primary metal layer on which the discontinuous surface coating is formed.

49. The method for forming a capacitor according to claim 48, wherein the primary metal layer comprises nickel, iron, chromium, copper, and alloys thereof.

50. The capacitor formation method according to claim 32, wherein the cathode lead includes a discontinuous surface coating.

51. The capacitor formation method according to claim 32, wherein the anode includes a metal.

52. The capacitor formation method according to claim 51, wherein the anode includes valve metal.

53. The capacitor formation method according to claim 52, wherein the anode is preferably selected from the group consisting of Al, W, Ta, Nb, Ti, Zr, and Hf.

54. The capacitor formation method according to claim 53, wherein the anode comprises aluminum.

55. The capacitor formation method according to claim 53, wherein the anode includes tantalum.

56. In addition, the anode is a foil, according to claim 51, the method for forming a capacitor.

57. The capacitor formation method according to claim 51, wherein the anode is etched.

58. The capacitor forming method according to claim 51, further comprising the step of compressing the metal powder into a single body and sintering it to form the anode.

59. The capacitor formation method according to claim 32, wherein the cathode comprises a conductive polymer or manganese dioxide.

60. The method for forming a capacitor according to claim 59, wherein the conductive polymer is selected from the group consisting of polythiophene, polyaniline, and polypyrrole.

61. The conductive polymer is defined by the following chemical formula A: Here, R １ and R ２ These are independently linear or branched C １ -C １６ Alkyl, C ２ -C １８ Alkoxyalkyl, C ３ -C ８ These represent cycloalkyl, phenyl, or benzyl, and these are C １ -C ６ Alkyl, C １ -C ６ Alkoxy, halogen or OR ３ It is either not replaced or replaced; or R １ and R ２ Both are linear C １ -C ６ Alkilen, C １ -C ６ Alkyl, C １ -C ６ Alkoxy, halogen, C ３ -C ８ Cycloalkyl, phenyl, benzyl, C １ -C ４ Alkylphenyl, C １ -C ４ Alkoxyphenyls, halophenyls, C １ -C ４ Alkylbenzyl, C １ -C ４ Alkoxybenzyl or halobenzyl, unsubstituted or substituted 5-, 6-, or 7-membered heterocyclic structures containing two oxygen elements; R ３ is hydrogen, linear or branched C １ -C １６ Alkyl or C ２ -C １８ Alkoxyalkyl, C ３ -C ８ These represent cycloalkyl, phenyl, or benzyl, and these are C １ -C ６ Alkyl substitution is either not substituted or is substituted; X is S; and The capacitor formation method according to claim 60, wherein n is an integer number sufficient to achieve an average molecular weight of 2 to approximately 500,000.

62. The method for forming a capacitor according to claim 60, wherein the conductive polymer is 3,4-polyethylenedioxythiophene.

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