Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/004—Details
  • H01G9/04—Electrodes or formation of dielectric layers thereon
  • H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
  • H01G9/052—Sintered electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/0029—Processes of manufacture
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/20—Direct sintering or melting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/20—Direct sintering or melting
  • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/141—Processes of additive manufacturing using only solid materials
  • B29C64/153—Processes of additive manufacturing using only solid materials using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y80/00—Products made by additive manufacturing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
  • C22C27/02—Alloys based on vanadium, niobium, or tantalum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/30—Process control
  • B22F10/36—Process control of energy beam parameters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/70—Recycling
  • B22F10/73—Recycling of powder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
  • B22F12/60—Planarisation devices; Compression devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/045—Alloys based on refractory metals
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• the present invention relates to a method for producing electronic components and / or porous components, in particular anodes, from valve metal powder by means of 3D printing and the use of a valve metal powder for the production of electronic components and / or porous components by means of 3D printing. Furthermore, the present invention relates to an anode, which is obtainable according to the inventive method and an electrical component, in particular a capacitor comprising the anode according to the invention.
• capacitors which are used as passive elements for storing electrical energy in electronic components such as smartphones, laptops, tablets, wearables and the like.
• capacitors which are characterized not only by a high energy storage density, but also by a small size, in particular a small thickness.
• valve metals are usually used, which are characterized by the fact that their oxides pass the potential in one direction, the current in one direction, but lock it in the other direction, when potential is lowered. Another property of the valve metals is that they have a natural oxide layer that prevents further oxidation and thus spontaneous ignition of the metal.
• Anodes of valve metals are usually produced by pressing and sintering suitable metal powder with finely divided primary structures or already sponge-like secondary structures. The solidification is usually carried out by solid phase sintering at temperatures in the range of 1000 ° C to 1500 ° C. In order to contact the pressed bodies electrically, the powder is pressed around a connecting wire. The minimum thickness of the anode is significantly limited by the diameter of the lead wire.
• a problem with this production method is the absorption of oxygen during the manufacturing process, which in particular has a negative effect on the hardness or ductility of the later Anode affects. It was found that a high oxygen content in the anodes leads to much worse electrical properties of the later capacitor.
• US Pat. No. 4,722,756 describes a method for reducing the oxygen content in tantalum or niobium sintered bodies, in which the sintering takes place in a hydrogen atmosphere in the presence of a reducing material.
• a reducing material beryllium, calcium, cerium, hafnium, lanthanum, lithium, praseodymium, scandium, thorium, titanium, uranium, vanadium, yttrium and zirconium and mixtures and alloys thereof are proposed.
• DE 33 09 891 describes a two-stage process for the production of valve metal sintered anodes for electrolytic capacitors, in which already sintered tantalum sintered bodies are deoxidized in the presence of a reducing metal such as magnesium.
• the metal is introduced together with the sintered body in a reaction chamber and heated simultaneously with this to temperatures between 650 ° C and 1150 ° C.
• the described methods have the disadvantage that the connection of the connecting wire to the anode deteriorates as a result of the treatment.
• the strength associated with wire and anode the so-called wire tensile strength
• is an important feature and poor or poor wire tensile strength constitutes a significant weakness in the further processing of the capacitor, which can result in mechanical failure of the capacitor.
• An alternative method of manufacturing capacitors is to print anodes of valve metals by applying metal-containing pastes to substrates.
• metal-containing pastes By applying thin layers to, for example, tantalum foils, anodes are accessible which sometimes fall well short of the thickness of conventionally produced components.
• DE 10 2011 116 939 describes a method for the production of distortion-free anodes by means of screen or stencil printing on thin tantalum or niobium foils.
• the anodes produced in this way have a vertical dimension of 25 to 250 ⁇ m.
• the pastes used are usually multi-component systems such as metal, binders, solvents and optionally other additives.
• these additives must be removed after printing.
• This is usually thermal, which means an additional process step.
• the thermal treatment may cause it to degrade but not be completely removed.
• the metal powder has a high carbon content, which has a negative effect on the electrical properties of the later anode.
• the sintering of the metal powder take place analogously to the conventional methods.
• this production method can be dispensed with a necessary for contacting the anode wire, since the substrate itself serves as a contact point. However, the substrate does not contribute to the capacitance of the capacitor, which reduces the energy density of the device. So here the real advantage of the valve metal, namely its high energy density, not fully exploited.
• US 2016/0008886 generally proposes a method of 3D printing in which metals, plastics, resins and other materials can be used.
• the present invention proposes as a solution to the abovementioned object a method for producing electronic components, in particular anodes, by means of 3D printing. It has been found that in this way the disadvantages of conventional production methods can be overcome.
• 3D printing or 3D printing in the sense of the present invention describes the computer-controlled, layered construction of three-dimensional workpieces according to predetermined dimensions and shapes.
• An object of the present invention is a method for producing an electronic component by means of 3D printing, comprising the following steps: a) providing a first layer comprising a valve metal powder; b) consolidating at least a portion of the valve metal powder of the first layer by selective laser irradiation. c) applying a second layer comprising a valve metal powder; d) consolidating at least a portion of the valve metal powder of the second layer by selective laser irradiation to form a composite of the first and second layers; e) repeating steps c) and d) to obtain the electronic component.
• Consolidation in the sense of the present application means the solidification of the powder particles by a melting or sintering process or a combination of the two process variants to form a physical bond.
• the inventive method allows the production of electronic components of small thickness with defined structures.
• the shape of the component can be chosen freely, so that any connections, for example, for the supply and removal of the stream, can be integrated into the component from the very beginning, whereby a subsequent attachment, for example by welding, is unnecessary.
• the electrical contacting is usually carried out via an anode lead wire whose integration in the anode body is usually associated with a loss of mechanical stability of the anode.
• the electronic component is an anode.
• Valve metal powders are characterized by their high storage density and are particularly suitable for use as power storage in electronic components.
• the valve metal used in the process of the present invention is preferably selected from the group consisting of aluminum, bismuth, hafnium, niobium, antimony, tantalum, tungsten, molybdenum and zirconium and mixtures and alloys thereof.
• the valve metal used is particularly preferably tantalum or niobium, in particular tantalum. It has surprisingly been found that the capacity of the later capacitor can be significantly increased if anodes of tantalum or niobium are used.
• valve metal is present together with one or more other metals.
• the further metal is selected from the group consisting of germanium, magnesium, silicon, chromium, tin, titanium and vanadium and mixtures and alloys thereof.
• the consolidation of the valve metal powder is carried out by selective irradiation with a laser. It has been found that the density of the electronic component can be controlled by suitable process control. In this way, both porous, so sponge-like structures are accessible, as well as compact structures with a low porosity. In particular, the careful adjustment of the laser is crucial for the desired end result. Accordingly, an embodiment is preferred in which the setting of the degree of consolidation of the powder via the energy input of the laser takes place.
• irradiation with the laser results in sintering of the powder.
• structures with a certain porosity are accessible.
• the presence of a porous structure is particularly important in anodes where a large surface area is beneficial.
• the irradiation with the laser leads to a melting of the powder.
• the adjustment of the energy input of the laser is locally variable. It has surprisingly been found that in this way the production of an electronic component, in particular an anode, is possible, which has locally different densities.
• the adjustment of the energy input of the laser is carried out in a manner that allows the formation of a density gradient in the x-direction and / or y-direction of the electronic component.
• the adjustment is preferably made such that there is a local increase in the density of the component.
• the density of the component at the connection points of the electrical contacts or be higher than in the rest of the component.
• the inventive method allows the production of electronic components, such as anodes, which have both a high energy density and a high wire tensile strength.
• the inventive method allows the production of sintered bodies with different dense substructures, in which the contacting sites are already introduced during the printing process. This makes it possible to produce any dense or porous structures. Furthermore, the volume ratio of anode to current flow can be adjusted by the method according to the invention.
• the power of the laser is in the range of 2 to 200W. Therefore, an embodiment in which the power of the laser is in the range of 2 to 200 W, preferably in the range of 5 to 100 W, is preferable.
• the focus of the laser which determines the local resolution, is preferably in the range from 1 to 200 ⁇ m, particularly preferably in the range from 5 to 100 ⁇ m. Limiting the focus to the specified range allows the fabrication of complex structures without adversely affecting the electrical and mechanical properties of the device.
• the feed of the laser is preferably 20 to 4000 mm / s, more preferably 50 to 2000 mm / s. In this way, an economically efficient Process management are achieved at the same time high quality of the product.
• the primary properties of the powder used in particular the particle size, are decisive for the electrical properties.
• the valve metal powder used has a particle size in the range of 5 to 120 ⁇ , preferably in the range of 10 to 50 ⁇ , particularly preferably 25 to 45 ⁇ , on. It has surprisingly been found that powders having a particle size in the claimed range allow the production of an anode which is distinguished by both excellent electrical properties and high mechanical stability.
• the inventive method is particularly suitable for the production of thin anodes, wherein the structure is carried out in layers. Therefore, an embodiment is preferred in which the thickness of the first layer is 5 to 100 ⁇ m, preferably 10 to 50 ⁇ m. Although the thickness of the individual layers may vary, an embodiment is preferred in which the thickness of the second layer is approximately equal to that of the first layer and is 5 to 100 ⁇ m, preferably 5 to 50 ⁇ m. In this way, a uniform structure of the anode is ensured, which in turn leads to a homogeneous energy density distribution.
• the method according to the present invention is characterized in that complex three-dimensional structures of arbitrary shape are obtained by selective irradiation with a laser from a powder layer.
• the powder layer may have a simple geometric shape, for example rectangular, so that it is possible to dispense with a complicated original shape.
• the process does not consolidate the entire valve metal powder, an embodiment of the process of the invention is preferred in which the process comprises the further step of freeing the final component of unconsolidated powder. This can be done, for example mechanically or by means of an air flow.
• the unconsolidated powder can be recycled and returned to the process.
• conventional production methods have the disadvantage that they depend on the use of binders and / or solvents, which are then removed consuming.
• the process according to the invention does not require any further additives. Therefore, an embodiment is preferred in which the use of other additives such as binders, solvents, sintering aids and the like is dispensed with.
• Another object of the present invention is the use of a valve metal powder for the production of an electronic component by means of 3D printing.
• the electronic component is an anode.
• Another object of the invention is the use of a valve metal powder for the production of a porous component by means of 3D printing.
• the valve metal powder is used in a method according to the present invention.
• the 3D printing method in particular the method according to the invention, is advantageous.
• the porous components may have an open porosity of 20 to 80%, preferably 40 to 60%, measured according to DIN 66139.
• the mean pore size is in the range of 5 nm to 5 pm, preferably in the range of 30 nm to 4 pm and particularly preferably in the range of 50 nm to 2 pm.
• the pore size distribution of the components measured e.g. with mercury porosimetry, may have one or more maxima with average pore diameters in the ranges mentioned.
• valve metal is selected from the group consisting of aluminum, bismuth, hafnium, niobium, antimony, tantalum, tungsten, molybdenum and zirconium and mixtures and alloys thereof.
• the valve metal is particularly preferably tantalum or niobium, in particular tantalum.
• the valve metal may be present together with one or more other metals.
• the further metal is selected from the group consisting of beryllium, germanium, magnesium, silicon, tin, chromium and vanadium and mixtures and alloys thereof.
• the valve metal powder for the use according to the invention preferably has a particle size in the range from 5 to 120 ⁇ m, particularly preferably 10 to 50 ⁇ m and very particularly preferably 25 to 45 ⁇ m. It has surprisingly been found that powders having a particle size in the claimed range are particularly suitable for use in 3D printing processes and have good handleability and processability.
• the valve metal powder used in the invention preferably has a carbon content of less than 50 ppm. More preferably, the carbon content is in the range of 0.1 to 20 ppm.
• the valve metal powder for the use according to the invention has a hydrogen content of less than 600 ppm, preferably 50 to 400 ppm. It has surprisingly been found that by limiting the hydrogen content to the stated values, the mechanical stability of the component can be increased.
• the nitrogen content of the powder used is preferably 5000 ppm or less, more preferably in the range of 10-2000 ppm, most preferably in the range of 10 to 1000 ppm.
• a nitrogen content outside the specified range has a negative effect on the electrical properties of the future capacitor and may also affect the processability of the powder during 3D printing.
• Valve metals have a natural oxide layer that prevents the spontaneous ignition of these powders.
• the valve metal powder for use according to the invention preferably has an oxygen content of 4000 ppm or less per m 2 BET specific surface area of the powder, more preferably an oxygen content in the range of 2000-3200 ppm per m 2 BET specific surface area. It has surprisingly been found that by limiting the oxygen content to the region according to the invention, the charge separation between the cathode and the anode can be improved, which leads to an increased storage capacity of the capacitor.
• the valve metal powder according to the use according to the invention preferably has an iron content of 10 ppm or less, more preferably 0, 1 to 8 ppm.
• An iron content within the claimed range ensures that the electrical properties of the later capacitor are not affected by the natural conductivity of the iron. Iron particles in or directly under the native oxide layer of the powder lead in the subsequent anodization in electrolytes to electrical breakdowns through the oxide layer and make the component unusable as a capacitor.
• the potassium content of the powder used according to the invention is preferably below 20 ppm, more preferably in the range of 0.1 to 10 ppm.
• the sodium content of the valve metal powder is 10 ppm or less, more preferably 0, 1 to 8 ppm. Potassium and sodium compounds in or directly under the native oxide layer of the powders lead to electrical breakdowns through the oxide layer in the subsequent anodization in electrolytes and make the component unusable as a capacitor.
• the content of nickel in the valve metal powder is 20 ppm or less, more preferably 0.1 to 10 ppm.
• the valve metal powder used in the invention may comprise phosphorus.
• the phosphorus content is preferably 300 ppm or less, more preferably 10 to 250 ppm. It has surprisingly been found that the sintering activity of the valve metal powder can be adjusted by the phosphorus content, wherein a content of phosphorus which is above the claimed range leads to an undesired loss of storage capacity of the later capacitor.
• valve metal powder is used in the present invention, which has a purity of 99%, preferably 99.9% and all particularly preferably 99.99% or more.
• the valve metal powder has the following composition, wherein the ppm data relate to mass fractions:
• Hydrogen in an amount of less than 600 ppm, preferably 50 to 400 ppm,
• Iron in an amount of less than 10 ppm, preferably 0, 1 to 8 ppm,
• Potassium in an amount of less than 20 ppm, preferably 0, 1 to 10 ppm,
• Nickel in an amount of less than 20 ppm, preferably 0, 1 to 10 ppm,
• Phosphorus in an amount of less than 300 ppm, preferably 50 to 200 ppm, and
• the valve metal powder have a bulk density of at least 1.5 g / cm 3 with a flowability of less than 60 s, preferably 30 s, and most preferably 10 s at 25 g powder through a 0.38 cm (0, 15 inch ) Funnels with a flow rate of at least 0.5 g / s. It has surprisingly been found that powders having a corresponding flow rate have particularly good processability in 3D printing processes.
• the amount of electrical energy that can be stored in a capacitor is determined inter alia by the surface of the powder used.
• a particularly high surface area of the powder usually results from a small diameter of the particles combined with a high degree of open porosity. If the particle diameters are too small, the metallic particles are completely converted into oxide during the anodization and no longer contribute to the capacity (through-formation). Therefore, an embodiment is preferred in which the valve metal powder has a BET surface area of from 0.001 to 10 m 2 / g, preferably from 0.001 to 5 m 2 / g, particularly preferably from 0.001 to 3 m 2 / g and very particularly preferably from 0, 01 to 1 m 2 / g.
• the inventive method is particularly suitable for the production of anodes. Therefore, another object of the present invention is an anode obtainable according to the method of the invention.
• the anode according to the invention preferably has an anode connecting wire.
• this anode lead wire is formed during printing of the anode simultaneously with this and integrated into it.
• the anode lead wire is realized by melting a corresponding region of the valve metal powder layer.
• the density of the anode at the junction of the anode lead wire is higher than in the remainder of the anode. In this way, a reliable power connection is ensured without adversely affecting the energy storage density.
• the method according to the invention makes it possible to control the density of the anode in a targeted manner by means of a corresponding process procedure. Therefore, the anode according to the invention preferably has a density gradient in the x-direction and / or the y-direction. In this way, the anode has a high energy storage density and a high wire strength. Preferably, the anode according to the invention has a porosity of at least 20% based on the total volume of the printed body. The porosity can be determined, for example, by means of mercury porosimetry.
• the inventive method is particularly suitable for the production of thin anodes. Therefore, an embodiment is preferred in which the anode has a thickness of 5 to 500 ⁇ m, preferably 10 to 300 ⁇ m and very particularly preferably 20 to 100 ⁇ m. Anodes of this thickness are particularly suitable for use in mobile devices that demand high performance.
• Another object of the present invention is a capacitor comprising the anode according to the invention.
• the capacitor can be obtained, for example, that the surface of the anode according to the invention electrolytically to amorphous metal oxide, such as. As Ta 2 Ü5 or Nb 2 Ü5, is oxidized.
• the thickness of the oxide layer which acts as a dielectric, is determined by the maximum voltage applied in the electrolytic oxidation, the so-called forming voltage.
• the counterelectrode ie the cathode
• the counterelectrode is applied by impregnating the spongy anode with, for example, manganese nitrate, which is thermally converted to manganese dioxide.
• the cathode may be formed by soaking the anode in a liquid precursor of a polymer electrolyte and, optionally, subsequently polymerizing it.
• the contacting of the electrodes can take place on the cathode side via a layer structure of graphite and conductive silver on the current conductors.
• Suitable powders are available from H.C. Starck Tantalum and Niobium GmbH, Germany available in different qualities. To solidify the metal powders, the commercially available TruPrint 1000 laser system from Trumpf, Germany, was used.
• the valve metal powder is placed in a reservoir and fed to the construction platform in portions.
• the powder is spread evenly over the build platform using a doctor blade or roller and selectively irradiated with a laser. With a high laser power and a longer exposure time, the powder melts, so that a dense, largely pore-free structure is formed. With a lower energy input, sintering of the powder occurs, wherein the energy input of the laser is selected so that the temperature of the powder bed is slightly below the melting temperature of the metal. Under these conditions, a rapid diffusion in the solid and a composite of the particles along their surface are possible, so that the porous internal structure of the particles is retained.
• FIG. 1 shows an anode of tantalum metal powder, which was produced according to the method according to the invention. The density differences within the anode can be clearly seen. In the lower part of the anode are three areas that have a very high porosity. These are residues from the powder bed of non-irradiated powder. The remaining area in the lower part shows larger molten particles with different densities. The four downwardly facing structures serve as contact terminals for the capacitor. In the upper part of the anode is an extensive area (about 60% of the total body) to recognize, which has large porous portions.

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• 2016
  • 2016-09-15 DE DE102016011098.8A patent/DE102016011098A1/de active Pending
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