Method of manufacturing anodes, cathodes of electrolytic capacitors

Abstract

The invention relates to the production of electrolytic capacitors based on tantalum, niobium, and niobium monoxide. Using the described method, blanks for anodes and cathodes, anodes and cathodes themselves are manufactured. The method of manufacturing such anodes and cathodes is realized either on a one device or on several devices united in a unified technological chain. The method of manufacturing anodes, cathodes of electrolytic capacitors and blanks for them based on tantalum, niobium, niobium monoxide (niobium oxide II) by using 3D printing technologies, includes coating a layer of metal powder or metal oxide, or paste or suspension containing particles of metal powder or metal oxide on a build platform, forming a layer of a printing product or a group of products. The forming of the desired product or group of products is carried out in the presence of a source of light.

Description

[0001] METHOD OF MANUFACTURING OF ANODES, CATHODES OF EEECTROEYTIC CAPACITORS, AND BEANKS FOR THEM BASED ON TANTALUM, NIOBIUM, NIOBIUM MONOXIDE (NIOBIUM OXIDE II) BY USING 3D PRINTING TECHNOLOGIES

[0002] TECHNICAL FIELD

[0003]

[0001] The present invention relates to the production of electrolytic capacitors based on tantalum, niobium, and niobium monoxide. Using the described method, blanks for anodes and cathodes, anodes and cathodes themselves are manufactured. The method of manufacturing such anodes and cathodes is realized either on a one device or on several devices united in a unified technological chain.

[0004] BACKGROUND OF INVENTION

[0005]

[0002] A number of technologies for manufacturing anodes, cathodes, and blanks for electrolytic capacitors based on tantalum, niobium, and niobium monoxide (niobium oxide II) are known. Capacitor-grade powders are used to produce capacitors. They usually have a large surface area and few impurities. Existing technologies for manufacturing such anodes have several limitations.

[0006]

[0003] About 60% of the tantalum metal produced worldwide is used for the production of capacitors. The capacitor manufacturing process and its different variants are well documented. New technologies are constantly being developed. A large number of patents, both valid and expired.

[0007]

[0004] Anodes and cathodes (blanks for them) made of these materials are porous structures of various shapes. The shape of such structures is limited by the manufacturing technology. Two manufacturing technologies are common.

[0008]

[0005] The most common involves powder pressing stages and subsequent sintering of the powder. Sometimes, various lubricants are used to increase the fluidity of the powder to fill the press molds more completely. The molds are usually cylinders or rectangular parallelepipeds, although there are also hollow cylinders with open ends or one closed end. For example, a capacitor manufacturing process chain is described in an overview in the following patent publications EP3192595B 1 pub. 17.04.2019, DE102013206603A1 pub. 16.10.2014, EP2984194B 1 pub. 26.10.2022, US11081290B2 pub. 03.08.2021, US4945452A pub. 31.07.1990 and others.

[0009]

[0006] The second technology is close to 3D printing. It is a technology for depositing pastes containing tantalum or niobium powder particles on tantalum or niobium foil. For example, patent DE10201111116939A1 pub. 02.05.2013 and DE10201920303057A pub. 14.05.2020 describe such a technology. These technologies are suitable for making only relatively small and thin capacitors, carbon contamination is possible when the polymer component of the paste is subsequently burned out.

[0007] In some cases, additional components are used to remove oxygen from tantalum or niobium (deoxidation by magnesium - Mg, or other alkaline earth metals). Sometimes, magnesium vapor treatment is carried out for the same purpose. For example, the description of the corresponding technologies is available in the pub. US8349030B 1 (08.01.2013), pub. US4537641A (27.08.1985), pub. US6447570B1 (10.09.2002) and others.

[0010]

[0008] Patent application DE102016011098A1 pub. 15.03.2018 describes in detail a technology for 3D printing anodes from valve metals by selective laser sintering / fusion / melting (LB-PBF technology group). However, the process described in the patent has low productivity, i.e., little suitability for mass production. It describes the use of laser light only with a Gaussian energy distribution in the focal spot and without the possibility of using laser light with a homogeneous distribution of laser light in the focal spot. This does not allow to achieve of homogeneity of properties in the volume of the product. The possibility of using large area illumination (area printing) to increase the productivity of 3D printing is not described. The main focus is on printing thin anodes with limited applicability. The use of lubricants and polymer binders is seen as undesirable, although it is the 3D printing technologies using lubricants and polymer binders that enable anode formation in many cases and high productivity. The limitations also affect the powders used for printing. The technology proposed in the patent does not allow the use of powders with low fluidity, such as those used in the production of high-voltage capacitors (large, irregularly shaped particles) or high-capacity capacitors (powders with particle sizes of less than 1-5 micrometers and low fluidity). In general, the technology described in the patent, printing modes, and materials used are realizable only in limited conditions of use of strictly defined equipment and cannot be widely used in the presented form, especially for mass production. The general principle described in this patent is known for a large number of technologies.

[0011]

[0009] Interest in the use of 3D printing (additive technologies) for anode printing is mentioned in patent KR102389784B1 pub. 22.04.2022. However, the patent mainly describes the technology for producing tantalum powders for 3D printing (additive technologies). The possibility of economically feasible 3D printing of anodes is regarded as economically impractical.

[0012]

[0010] Although tantalum and niobium powder printing technologies are now being actively developed, specifically designed and manufactured powders for 3D printing are of poor suitability for making capacitors. For example, in patent application US 2023 / 0286043 Al pub. 14.09.2023, the described spherical tantalum powders are opposed to capacitor quality powders, because anodes and cathodes made of powder with spherical particle shape have a smaller surface area and therefore low capacitance. Powders of tantalum, niobium, and niobium oxide of different qualities are used for the production of capacitors. The characteristics of the powder used determine the characteristics of the capacitors produced. Powders for the production of capacitors are made by several technologies. However, most powders of the mentioned metals are not suitable for many 3D printing technologies due to low fluidity, particle size distribution, and other characteristics. For example, patent application CN111819016A pub. 23.10.2020 describes a method of producing spherical tantalum powders specifically for 3D printing, and there are similar descriptions in other patents. Powders produced specifically for the manufacture of capacitors for 3D printing (additive technologies) are not considered.

[0013] [Oi l] Many patents describe how to make electronic components using additive technology (3D printing). This also applies to capacitors. For example, patent applications US20190134898A1 pub. 27.07.2016 and US20230130339A1 pub. 27.04.2023 describe methods of 3D printing capacitors. For mass production, the technology described, for example, in patent US 11760010B2 pub. 19.09.2023 is potentially suitable, but this method has a number of disadvantages, for example, it does not allow 3D printing of capacitors without degrading the quality of polymer additives (carbon contamination).

[0014] INVENTION DISCLOSURE

[0015]

[0012] The technical problem and the technical result of the invention consist is to increase the productivity of existing and new production facilities of electrolytic capacitors based on tantalum and niobium, niobium monoxide, to improve the performance and design characteristics of such capacitors, to increase the economic efficiency of production, to expand the variety of capacitors produced, to improve the safety of the production process.

[0016]

[0013] Achieving this goal is possible by using a method of manufacturing anodes, cathodes of electrolytic capacitors and blanks for them based on tantalum, niobium, niobium monoxide (niobium oxide II) by using 3D printing technologies, including spreading a layer of metal powder or metal oxide or paste or suspension containing particles of metal powder or metal oxide on a building platform, forming a layer of a desired product or a group of products.

[0017]

[0014] The manufacturing method is characterized by the process of forming a desired product or a group of products in the presence of a light source:

[0018]

[0015] When dry powders are used for manufacturing the product or group of products using sintering, fusing, or melting technologies, the process is carried out using optical radiation;

[0019]

[0016] When dry powders are used to manufacture a desired product or group of products and a polymeric binder is used, the layer of the product or products is formed by printing with a polymeric binder that permeates the powder at selected points, then the polymeric binder is either allowed to cure on its own, or the polymeric binder is exposed to heat, or the polymeric binder, if the composition used is capable of photopolymerization, is exposed to optical radiation at the photopolymerization wavelength of the composition used.

[0017] When pastes or suspensions with metal powders or metal oxide powders are used to manufacture the product or group of products, the layer of the product or products and the photopolymerization ability of the dispersion medium composition are exposed to light at the photopolymerization wavelength of the selected composition;

[0020] - The building platform is moved downwards by the height of the formed layer;

[0021] - The above steps are repeated until the product is completely formed.

[0022]

[0018] In one method variant, when dry powders are used to manufacture a product or group of products and sintering, fusing, or melting technologies are used, the process is carried out using laser radiation.

[0023]

[0019] In one method variant, when dry powders are used to manufacture the product or group of products and sintering, fusing, and melting technologies are used, the process is carried out using a beam of electrons generated by an electron gun.

[0024]

[0020] In one method variant, when dry powders are used to manufacture a product or group of products and a polymeric binder is used, the layer of the product or products is formed by printing with a polymeric binder that permeates the powder at selected points, then the polymeric binder is either allowed to cure on its own, or the polymeric binder is exposed to heat, or the polymeric binder, in the case of the photopolymerization ability of the composition to be used, exposed to laser radiation at the photopolymerization wavelength of the composition to be used at selected areas.

[0025]

[0021] In another method variant, a laser beam, other optical radiation source, or electron beam is point by point or continuously moved across the surface of the sprayed powder or paste to form a single layer of the product or products.

[0026]

[0022] In another method variant, to form a single layer of the product or products, the laser beam, another optical light source, or a large-area illuminated electron beam treats the surfaces of the powder, paste, or slurry section by section.

[0027]

[0023] In another method variant for forming one layer of a product or products, the laser beam, another optical radiation source, or electron beam forms a radiation spot on the surface of the product that is identical in shape to the shape of the anode or cathode layer.

[0028]

[0024] In another method variant for forming one layer of products, the laser beam, another optical radiation source, or electron beam forms a radiation spot on the surface of the workpieces whose shape coincides with some or all of the cross sections of the anodes and cathodes at once.

[0029]

[0025] In an alternative way of carrying out the process, the print head is moved above a build area with a layer of metal powder or metal oxide (tantalum and niobium), drops of polymer binder are deposited at a place where layers of anode blanks or cathode blanks are formed, the formed layers of anode blanks and cathode blanks are arranged on the build platform, printed anode and cathode blanks are surrounded by process powder, drops of polymer binder wet the powder layer in the place of formation of the future layer of anode and cathode blanks, moving light source is moved over the wetted polymer binder, under the influence of radiation the next layers of anode or cathode blanks are formed.

[0030]

[0026] In another method variant, when a light source is used, the polymer binder-wetted areas are exposed to radiation, wherein portions of the surface of the printing area are illuminated.

[0031]

[0027] In another method variant, the gas process medium in which the 3D printing process takes place may be a vacuum or various gases and mixtures thereof.

[0032]

[0028] In a particular variant, a foil layer is applied to the build platform before printing.

[0033]

[0029] The above-mentioned and other objectives, advantages and features of this invention will be made more evident in the following non-limiting description of its embodiments, provided as example with reference to attached drawings.

[0034] BRIEF DESCRIPTION OF FIGURES

[0035]

[0030] The essence of invention is explained by drawings wherein:

[0036]

[0031] Fig.1 The general scheme of the device (3D printer) for printing anode or cathode blanks made of tantalum, niobium or niobium monoxide for electrolytic capacitors is shown.

[0037]

[0032] Fig.2 Depicts a schematic of layer formation of anode or cathode blanks made of tantalum, niobium or niobium monoxide for electrolytic capacitors. Schematic of 3D printing point by point.

[0038]

[0033] Fig.3 Depicts a schematic of layer formation of anode or cathode blanks made of tantalum, niobium or niobium monoxide for electrolytic capacitors. Schematic of 3D printing point by point 3D printing scheme section by section.

[0039]

[0034] Fig.4 Depicts a schematic of layer formation of anode or cathode blanks made of tantalum, niobium or niobium monoxide for electrolytic capacitors. Schematic of 3D printing layer by layer for individual anodes or cathodes.

[0040]

[0035] Fig.5 Depicts a schematic of layer formation of anode or cathode blanks made of tantalum, niobium or niobium monoxide for electrolytic capacitors. Schematic of 3D printing layer by layer for several or all anodes or cathodes in a layer.

[0041]

[0036] Fig.6 Depicts a schematic of layer formation of anode or cathode blanks made of tantalum, niobium or niobium monoxide for electrolytic capacitors. Schematic of 3D printing using a movable print head and a movable light source.

[0042]

[0037] Fig.7 Depicts a schematic of layer formation of anode or cathode blanks made of tantalum, niobium or niobium monoxide for electrolytic capacitors. Schematic of 3D printing using a movable print head and a fixed light source.

[0043]

[0038] Fig.8 Schematic representation of the difference between coated and composite powders.

[0039] Fig.9 A model of the 3D printer building platform is depicted, showing the location of the heating and thermal insulation device.

[0044]

[0040] Fig.10 Models of anode and cathode blanks without internal channels and with internal channels are depicted.

[0045]

[0041] Fig.11 The model of formation of capacitor leads is depicted. Scheme for welding the capacitor wire to one side of the anode or cathode blank.

[0046]

[0042] Fig.12 The model of formation of capacitor leads is depicted. Scheme of welding the capacitor wire to one of the sides of the anode or cathode blank in a blind hole.

[0047]

[0043] Fig.13 Schematic representation depicting the difference between the processes of sintering, fusion and complete melting of metal powders.

[0048]

[0044] Fig.14 The model of forming of capacitor leads is depicted. Scheme of welding the capacitor wire to one of the sides of the anode or cathode blank on the section with full material.

[0049]

[0045] Fig.15 The model of forming of capacitor leads is depicted. Scheme of welding the capacitor wire to one of the sides of the anode or cathode blank on the section with full material and blind hole.

[0050]

[0046] Fig.16 The model of forming of capacitor leads is depicted. Scheme of welding of the capacitor wire to one of the sides of the anode or cathode blank on the section with full material and blind hole, branching of the section with full material and stiffening ribs.

[0051]

[0047] Fig.17 Schematic representation depicting the arrangement of niobium or tantalum foil during 3D printing on foil.

[0052]

[0048] Fig.18 Schematic representation depicting the arrangement of niobium or tantalum foil during 3D printing on foil. Printing in multiple layers of anodes or cathodes with additional build platforms.

[0053]

[0049] Fig.19 Schematic representation depicting the arrangement of anode and cathode blanks during 3D printing in several layers without the use of technological supports.

[0054]

[0050] Fig.20 Schematic representation depicting the arrangement of anode and cathode blanks during 3D printing in several layers using technological supports.

[0055]

[0051] These drawings do not cover and, moreover, do not limit the entire scope of embodiments of this technical solution, but are only illustrative examples of particular cases of implementation thereof.

[0056] EMBODIMENTS OF INVENTION

[0057]

[0052] According to the example of invention embodiment shown in Fig. 1 in an embodiment of the described method for manufacturing anodes, cathodes of electrolytic capacitors, and blanks therefor based on tantalum, niobium, niobium monoxide (niobium oxide II) by using 3D printing technologies, the printing process is as follows.

[0053] A layer of metal powder (niobium, tantalum) or metal oxides (niobium monoxide), or a paste, or a suspension containing particles of powder of tantalum, niobium, niobium monoxide, is spread on the build platform 6, located in the build chamber 1, using a movable leveling device (recoater) 8, from the feed chamber 2. Excess powder, paste, or slurry can be discharged into chamber 3.

[0058]

[0054] Next, the product layer 12 is formed using the radiation source 9. The radiation 10 may be laser light, other optical radiation, electron beam. The product 12 may be one or more.

[0059]

[0055] In case the layer is formed with a polymer binder, a movable print head 17 is used. If necessary, curing of the polymer binder is carried out using the movable radiation source 18. The radiation source 18 may emit either thermal radiation in the case of thermal curing of the polymer binder or optical radiation in the case of curing the polymer binder by using a photopolymerization process. In the case of easy-melting polymer binders and investment polymer compositions, the radiation source 18 may not be used. In the case where pastes or suspensions based on photopolymer compositions are used and no radiation source 9 is needed, only radiation source 18 is used. In this case, both the printhead 17 and the radiation source 9 may not be used.

[0060]

[0056] Further, the building platform 6 is shifted to the thickness of the layer of powder, paste, or suspension by using the movable piston 7.

[0061]

[0057] The described actions are repeated.

[0062]

[0058] In the process of building the product or products 12, a work layer of powder, slurry, and paste 11 is formed.

[0063]

[0059] If necessary, double-sided feeding and discharge of excess powder, paste, or suspension is possible. Feeding is carried out from the additional chamber 4. Discharge is carried out in chamber 5.

[0064]

[0060] To monitor the 3D printing process, a camera 13 operating in the optical range is used.

[0065]

[0061] Additionally, a camera operating in the IR or UV range can be installed.

[0066]

[0062] The printing process can be carried out in a vacuum (all variants of the technology), in a protective atmosphere (argon, nitrogen, helium, mixtures of gases, etc.), or in a normal atmosphere in the case of pastes, suspensions, or polymer binders.

[0067]

[0063] Sensor 14 is used to monitor oxygen content. Sensor 15 is used to monitor water content (humidity control). Sensor 16 is used to monitor hydrogen content. Other sensors can be installed and used.

[0068]

[0064] The process of layer-by-layer fabrication of an anode or cathode blank using a radiation source 9 is carried out in different ways for different technologies. Easers and other radiation sources, an electron beam generated by an electron gun, can be used.

[0069]

[0065] In the case of optical radiation, sources with wavelengths in the range from 350 nm to 16 pm can be used.

[0066] The power of the optical radiation sources can be in the range of up to 200 W in the case of photopolymerization processes and from 100 W to 200 kW in the case of sintering, fusion, and full melting processes.

[0070]

[0067] The power of the electron gun can be from 1 to 6 kW. A more powerful electron gun can be used, but this is usually excessive.

[0071]

[0068] In the case of laser light, the design of the light source 9 allows for uniform energy distribution in the cross-section of the laser beam. Other energy distribution profiles in the cross-section of the laser beam, including asymmetric ones, may also be used.

[0072]

[0069] Other optical radiation sources similarly require uniform energy distribution in the beam cross-section. Other profiles of energy distribution in the beam cross-section, including asymmetric ones, can be used as well.

[0073]

[0070] Several radiation sources 9 may be installed. Partial or complete overlapping of areas of lighting of several radiation sources is allowed. It is possible to install several different radiation sources with different parameters. For example, a radiation source for carrying out the sintering process and a radiation source for carrying out the complete melting process.

[0074]

[0071] Feed chambers 2 and 4 may provide for feeding the print material from the bottom, top, and sides.

[0075]

[0072] Fig. 2.1-2.4 show different approaches to constructing layers of anode or cathode blanks.

[0076]

[0073] To form one layer of the product or products, the laser beam, other optical radiation source or electron beam 10 point by point or continuously moves on the surface of the applied powder or paste (Fig. 2). The radiation source 9 provides sequential treatment of the surface of the applied powder or paste (suspension) - 19. The layers of individual anodes or cathodes 20 are formed step by step. Partially finished blanks of anodes and cathodes 12 are under the layer of untreated material. The shape of the radiation spot on the treated surface is typically a circle or ellipse, other radiation spot shapes may be used. The radiation source 9 may be considered as a point radiation source in the case of a small surface treatment area. In the case of treating a large surface area, optical designs may be used to avoid radiation divergence. The size of the radiation spot on the surface may be from 5 to 500 microns. The speed of surface treatment, the trajectory of the radiation spot movement are experimentally found parameters and may depend on the characteristics of raw materials.

[0077]

[0074] Fig. 3 shows a 3D printing process with a large area lighted. In this case, the surface treatment of the powder, paste, or slurry occurs section by section. In some cases, continuous motion of the spot is possible, but the shape of the anodes and cathodes 12 must be maintained. The spot 10 has a rectangular shape, although it is also possible to use a spot 10 with a different geometry, such as an elliptical shape in the case of anodes with a circular cross-section. Large area lighting techniques are only applicable to printing using optical radiation sources. The trajectory of motion, speed of motion are experimentally determined for specific raw materials.

[0078]

[0075] Fig. 4 shows a 3D printing process of layers of anodes and cathodes 12 with one anode or cathode layer 12 being lighted at a time. In this scheme, the light spot 10 matches the shape of the anode or cathode layer. The time of lighting of one layer depends on the technology and, variants of raw materials used. The trajectory of the light spot in this case is usually not important in this case, although it can be optimized.

[0079]

[0076] Fig. 5 shows the process of 3D printing of anode and cathode layers 12 with the lighting of several layers of anode and cathode blanks at a time by light spot 10. It is also possible to irradiate all simultaneously printed anode and cathode blanks 12 at once. The shape of the radiation spot 10 must coincide with several or all cross-sections of anodes and cathodes at once. In case of mass production with simultaneous lighting by a spot 10 of all cross-sections of anodes and cathodes 12, it is allowed to use optical configurations with a fixed shape of a spot 10.

[0080]

[0077] By using the printing head 17, several versions of the technology are realized.

[0081]

[0078] The printing head 17 moves above the building area covered by a layer of metal powder or metal oxide (tantalum and niobium) - Fig. 6. Droplets of polymer binder 21 are sprayed at the site where the layers of anode or cathode blanks 12 are formed. The already formed layers of anode and cathode blanks are arranged on the building platform 6. The already printed anode and cathode blanks are surrounded by the process powder 11. Droplets of polymer binder wet the powder layer at the site where the future layer of anode and cathode blanks 22 is formed. A movable radiation source 18 moves over the polymer binder wetted areas 22 and exposes them to radiation 23 in areas 24. The radiation 23 may be optical radiation in the range of 350 nm to 16 microns or thermal radiation (IR radiation). The following layers of anode or cathode blanks 25 are formed by exposure to radiation 23.

[0082]

[0079] The movable radiation source 18 may be optional in the case of polymer binders capable of self-curing or the use of radiation source 9 (Fig. 7).

[0083]

[0080] In the case of the radiation source 9, radiation 10 is used to expose the polymer binder wetted areas 22. It is possible to light up a part of the surface of the printing area, or the entire printing area.

[0084]

[0081] The gas process environment (atmosphere) in which the 3D printing process takes place can be a vacuum (pressure less than 3.3 kPa) or various gases and their mixtures. Printing can be carried out in argon, nitrogen, or helium. It is possible to use mixtures of gases, for example, mixtures of argon and nitrogen. Nitrogen may be used to prevent penetration of oxygen into the anode and cathode blanks. If oxygen penetrates the anode and cathode blanks, tantalum and niobium oxides may form, which may subsequently cause capacitors to fail or shorten their lifetime. In some cases, mixtures of the above gases with oxygen can be used to partially oxidize the surface of anodes or cathodes, but the formed oxide films must be removed at subsequent stages of capacitor production.

[0085]

[0082] In some cases, deoxidizing metal vapors may be available in the gas process environment (atmosphere) in which the 3D printing process takes place. The most common deoxidizing metal is magnesium (Mg). The addition of magnesium vapor is necessary for the reduction of tantalum or niobium from the oxide film on the surface of the formed anode or cathode blanks. The resulting magnesium oxide (MgO) is removed at subsequent stages of capacitor production.

[0086]

[0083] Hydrogen added to the gas process environment (atmosphere) can also be used for the reduction of niobium and tantalum from oxides.

[0087]

[0084] In the case of using polymer binders to form anode and cathode blanks, it is possible to carry out 3D printing processes in a gas process environment based on atmospheric air purified from solid particles.

[0088]

[0085] When using an electron gun as a source of electron beam flow, 3D printing is done in a vacuum only.

[0089]

[0086] In other cases, the composition of the gas process environment (atmosphere), the velocity of gas flows, the direction of gas flows, the requirements for the degree of gas purification may depend on the raw materials used, the use of polymer binders and lubricants, the requirements for the characteristics of the capacitors produced, etc.

[0090]

[0087] As raw materials can be used powders of tantalum, niobium and niobium monoxide without impurities, powders with lubricants to provide fluidity of powders, coated powders, composite powders, pastes based on tantalum powders, niobium and niobium monoxide powders mixed with polymer compositions with the ability to cure by optical or thermal radiation, flowable suspensions based on tantalum, niobium and niobium monoxide powders mixed with polymer compositions with the ability to cure by optical or thermal radiation.

[0091]

[0088] The described method of manufacturing anodes, cathodes of electrolytic capacitors, and blanks for them based on tantalum, niobium, niobium monoxide (niobium oxide II) by means of 3D printing technologies is also suitable for manufacturing capacitors from other valve metals. Aluminum, titanium, tungsten, tungsten, chromium, zirconium, hafnium, zinc, vanadium, bismuth, and antimony are considered to be valve metals, i.e., they form an oxide film on the surface and conduct electric current only in one direction through the oxide of this metal.

[0092]

[0089] For 3D printing tantalum, niobium, and niobium monoxide powders of capacitor quality are used, i.e., powders specially produced for the manufacture of capacitors. Tantalum, niobium, and niobium monoxide powders made specifically for 3D printing can be used, but their chemical composition should allow to make electrolytic capacitors from them.

[0090] The chemical composition of the used tantalum, niobium, and niobium monoxide powders should allow making electrolytic capacitors from them. The chemical composition may change during the printing process, for example, when exposed to nitrogen or printing in magnesium vapor. In some cases, additional impurities may be allowed for process manufacturability, such as phosphorus impurities, to reduce compression of the powders during sintering. Undesirable impurities or impurities arising in the printing process can be removed at subsequent stages of capacitor production, for example, carbon after annealing of polymer binders or magnesium oxide after magnesium vapor treatment.

[0093]

[0091] Regardless of the type of 3D printing raw material, a layer of material must be formed in the 3D printing chamber. This layer must not contain any layer breaks, i.e., it must be continuous. In the case of dry powders, it is necessary to ensure sufficient flowability of these powders. In the case of lubricants, polymer binders, pastes, and suspensions, the content of organic and inorganic additives should allow the formation of a continuous layer without layer breaks. Viscous pastes and suspensions must not contain gas bubbles.

[0094]

[0092] The tantalum, niobium, and niobium monoxide powders used may be pre-cleaned of oxide film and oxide film degradation products. In some cases, it is acceptable to keep such powders before 3D printing under conditions that retard or prevent the formation of oxide film.

[0095]

[0093] Mixtures of powders may be used. For example, mixtures of tantalum powders with magnesium powders.

[0096]

[0094] In dry powder 3D printing, printing is possible by laser sintering, laser fusion, full laser melting, electron beam sintering, electron beam fusion, full electron beam melting, using a movable print head 17 (binder components are added after the powder layer is formed).

[0097]

[0095] In the case of the use of lubricants, i.e., compositions that increase the flowability of powders, laser sintering, laser fusion, and full laser melting, using the print head 17 (binder components are added after the powder layer is formed) can be used.

[0098]

[0096] The lubricants may be based on one or more compounds (compositions). The compounds composing the lubricants may be inorganic, such as water, or organic, such as mixtures of propylene glycol and glycerin.

[0099]

[0097] During the printing process, lubricants can be removed by vaporization by heating or directly by heating with laser light. Heating can be carried out by an integrated heating system. During the heating process, the lubricants must be completely or partially vaporized. Residual lubricants can be removed in subsequent stages of capacitor production.

[0100]

[0098] Lubricants can be mixed with tantalum, niobium, or niobium monoxide powders in a prior or immediately before the 3D printing process.

[0099] In the case of coated powders, all of the technologies mentioned above are applicable. Coated powders are used to provide fluidity to coarse or highly dispersed powders and to introduce deoxidizing metals into the 3D printing process. Various solid polymer compositions or deoxidizing metals such as magnesium can be used as coatings.

[0101]

[0100] If coated powders are used, it is possible to form anode and cathode blanks by sintering or fusing the powders. Partial sintering, fusion, and complete melting of the powder coating occur during the 3D printing process. The metal particles themselves may or may not undergo sintering, fusion, or full melting processes, or may undergo these processes. The printed blanks are then sent to the next stages of capacitor manufacturing.

[0102]

[0101] Meltable, vaporizable, and burnable polymer compositions can be used for coating powders. Burn-out polymer compositions should have low ash content. The polymer compositions may be melted (the molten polymer composition flows from the workpiece), vaporized (the polymer composition evaporates from the workpiece), or annealed (the polymer composition is fired from the workpiece). Next, impurities need to be removed, especially in the case of the polymer compositions being burned out (carbon impurities).

[0103]

[0102] Deoxidizing metals such as magnesium can be used to coat powders. Due to its low melting point (compared to tantalum, niobium, and niobium monoxide), magnesium can be used to coat tantalum, niobium, and niobium monoxide powders. Coated powders have better flowability than coarse or highly dispersed powders. Due to the low boiling point (compared to tantalum, niobium, and niobium monoxide), magnesium vapors produced during the printing process recover tantalum and niobium from their oxides, thus reducing the oxygen content in the anode or cathode blank.

[0104]

[0103] Coated magnesium powders can be sintered, fused, and fully melted during the 3D printing process. The formed blanks are then sent to the next stages of capacitor manufacturing. In the case of magnesium coating, this is sintering followed by purification of the blanks from magnesium oxide formed during the reaction of magnesium vapor with tantalum and niobium oxide films.

[0105]

[0104] There may be complete vaporization or melting of magnesium in the 3D printing process, followed by sintering, fusion, and complete melting of tantalum, niobium, and niobium monoxide powders.

[0106]

[0105] In case of formation of vapors of powder coating materials, their removal from the building area is provided by the flow of the gas process medium.

[0107]

[0106] The technology of 3D printing of anode and cathode blanks of electrolytic capacitors using composite powders is completely identical to the technology of 3D printing with coated powders.

[0107] The difference is that coated powders contain only one metal or oxide particle, while composite powders may contain several metal or oxide particles.

[0108]

[0108] Fig. 8 demonstrates the difference between powders. In the case of coated powders, only one metal or metal oxide particle 26 is coated with the polymer composition or deoxidizing metal 27. In the case of composite powders, two or more metal or metal oxide particles 28 are in the medium of the polymer composition or deoxidizing metal 29.

[0109]

[0109] The coated and composite powders are sintered, fused, or fully melted using radiation source 9 or moving radiation source 18.

[0110]

[0110] In the case of complete vaporization of the polymer composition or deoxidizing metal, the tantalum, niobium, and niobium monoxide powders are sintered, fused, or completely melted using radiation source 9 or using the movable radiation source 18.

[0111]

[0111] In the case of using the print head 17, first, a layer of tantalum, niobium, and niobium monoxide powder is formed using the leveling device (recoater) 8. Next, using the print head 17, the polymer composition 21 is spread at the places where the layer of anode or cathode blanks is formed. The polymer composition 21 permeates the powder layer due to capillary forces, forming a layer 22 wetted with the polymer composition for the future anode or cathode blank layer.

[0112]

[0112] Different variants of this technology are used.

[0113]

[0113] If the polymer composition is capable of self-curing, no further processing of the workpiece layer is carried out. Typically, these are polymer compositions with a low melting point (up to 200°C), such as paraffin. Then the movable print head 17 must provide the melting of the polymer composition. Polymerizable polymer compositions that polymerize in air or a mixture, such as epoxy resins, are also used. In this case, the movable printhead must be able to store the polymer composition without air access or allow mixing of the polymer composition components during the printing process.

[0114]

[0114] If polymer compositions with photopolymerization or heat curing ability are used, then after placing the polymer composition at the desired locations to form a layer of anode and cathode blanks, a photopolymerization or controlled heat curing process is carried out. The photopolymerization and controlled heating curing processes are carried out using a movable radiation source 18. It is possible to use a radiation source 9 for providing photopolymerization and curing processes.

[0115]

[0115] After the 3D printing process has been carried out and the anode or cathode blanks are fully formed, the following operations are performed to manufacture the anodes or cathodes. Usually, it is removal of the photopolymer composition, sintering of the anode and cathode blanks, and cleaning of impurities.

[0116] The polymer compositions when using print head 17 should be either meltable, vaporizable, or burnable compositions with low ash content.

[0116]

[0117] Paste and liquid suspensions for 3D printing consist of metal or metal oxide particles - dispersed medium, polymer composition - dispersion medium. The polymer composition must be capable of photopolymerization or curing under heat. In some cases it is acceptable to use polymer compositions with the ability to cure by cooling, air, or additional reagents, but in general the use of such polymer compositions should be avoided due to the possibility of curing in feed chambers, on leveling devices, throughout the build area, as this can be costly to clean equipment.

[0117]

[0118] Paste and liquid suspensions are in general form suspensions, but pastes are compositions without the ability to spread on their own in the time required to carry out the process of printing at least one layer, and liquid suspensions are compositions with the ability to spread on their own in less time than is required to print at least one layer.

[0118]

[0119] In 3D printing, a layer of paste or liquid suspension is formed by means of a leveling device (recoater) 8. Next, the polymer composition is cured by the process of photopolymerization or by thermal radiation. For this purpose, a radiation source 9 or a movable radiation source 18 may be used.

[0119]

[0120] After completion of the 3D printing process, the anode and cathode blanks are cleaned of residual paste or suspension slurry. If necessary, they are exposed to optical radiation or heat to complete the curing process.

[0120]

[0121] Polymer compositions for pastes and liquid suspensions must be either meltable, vaporizable, or burnable (low ash content). The use of colorants without technological functions is allowed.

[0121]

[0122] Next, the photopolymer composition is melted, vaporized, and burned out of the anode and cathode blanks. Then the blanks are sintered and cleaned of impurities. In the case of polymer compositions, the impurity is carbon.

[0122]

[0123] When using any polymer compositions as lubricants, paste bases, liquid suspensions, coating of powders during subsequent heat treatment, reduction of linear dimensions of anode and cathode blanks may occur. Usually, the reduction of dimensions along one axis is 5-15% of the original workpiece. In case of large anodes and cathodes (more than 5 cm along one axis), when designing an anode or cathode, it is necessary to take into account the possibility of its destruction and add elements that prevent destruction during the reduction of dimensions.

[0123]

[0124] Compositions of lubricants, pastes, liquid suspensions, and coated powders can be composed of inorganic and organic compounds. For example, a mixture of water and glycerin.

[0124]

[0125] The building platform 6 can be optionally equipped with a heating device 30 (Fig.9). Heating from 100°C to 900°C may be provided. Typically, 250°C and 500°C. Heating of the building area is necessary to reduce the thermal gradient. If the thermal gradient is significant, internal stresses may accumulate in the anode and cathode blanks, and cracking and fracture of the anode and cathode blanks may occur. Heating can be used to accelerate 3D printing processes because the energy required for sintering, fusion, and complete melting will be less. Heating can be used to melt or vaporize photopolymer compositions. Burning out the photopolymer compositions using the heating device 30 is not recommended. Additional thermal insulation is provided by the thermal insulation layer 31. The movement of the building platform 6, the heating device 30, and the thermal insulation layer 31 is carried out by a movable piston 7. If necessary, additional water or air cooling is provided in the entire process unit.

[0125]

[0126] When 3D printing tantalum, niobium, and niobium monoxide anode and cathode blanks, internal channels are formed if necessary. Internal channels are necessary to provide access to liquid and gas process media at subsequent stages of anode production, to ensure melting, uniform evaporation and burning of polymer binders if they are used in the volume of anode or cathode blanks, access to vapors of deoxidizing metals (magnesium) when cleaning anode and cathode blanks from oxygen, cleaning from reaction products of magnesium vapor with tantalum and niobium oxides - magnesium oxide, formation of uniform dielectric layer (tantalum and niobium oxides), uniform formation of solid electrolyte layer (manganese oxide), uniform formation of polymer electrolyte layer, uniform access of liquid electrolyte during exploitation.

[0126]

[0127] Fig. 10 shows an anode or cathode blank without internal channels 32, an anode or cathode blank with internal channels 33, and internal channels 34. The demonstrated example of internal channels 34 is not the only possible example. The size, shape, direction, and mutual intersection of the internal channels 34 may be different. This is determined during the design of a particular anode or cathode. The shape of the anode or cathode blanks is not limited to a cylinder or rectangular parallelepiped.

[0127]

[0128] The internal channels are formed by not sintering, fusing, or completely melting the metal powder during printing, not solidifying the polymer composition, or not placing the polymer composition in place of the channels.

[0128]

[0129] The production of anode and cathode blanks also ensures the production of capacitor leads. In classical variants of the technology, capacitor leads are produced either by placing tantalum or niobium capacitor wire in metal powders or niobium monoxide during powder pressing, or capacitor wire is welded to anode or cathode blanks after sintering and cleaning, or anode or cathode is produced on tantalum or niobium foil, the foil serves as a capacitor lead.

[0129]

[0130] When 3D printing anode and cathode blanks, it is possible to realize several ways of manufacturing capacitor leads.

[0130]

[0131] When 3D printing anode and cathode blanks without any additional elements for attaching capacitor leads, such capacitor leads are welded to one side of the anode or cathode. For example, Fig. 11 shows how capacitor leads 36 are welded to anode 35 at contact point 37. This method of forming capacitor leads is already in use for the manufacture of capacitor leads, although it is not yet widespread and is considered preferable to placing the capacitor wire in tantalum, niobium, and niobium monoxide powder before pressing the powder.

[0131]

[0132] In 3D printing, it is possible to form process holes for mounting and welding of capacitor wire to form the anode or cathode lead. Fig. 12 shows an implementation of such an approach. The anode or cathode 38 is printed with a process hole 39. Next, capacitor wire 36 is placed in the process hole 39 and welded to the anode or cathode 38. This approach is also realizable with powder technologies, but due to the inability to accurately maintain dimensions, it is not typically used. When using 3D printing technologies to print anodes and cathodes, it is possible to maintain sufficient product precision to place and weld the capacitor wire to form the anodes and cathodes.

[0132]

[0133] When using 3D printing technology based on the treatment of metal powder or metal oxide with optical radiation (laser or other sources of optical radiation) or electron beam, it is possible to produce anode and cathode blanks with a variable density of metal or metal oxide.

[0133]

[0134] The processes occurring in a metal or metal oxide powder depend on the amount of energy transferred per unit time. These processes are controlled by changing the power of the radiation source and the time of treatment of the powder layer surface. In this case, there can be sintering of metal or metal oxide particles - no liquid phase is formed, fusion of metal or metal oxide particles - part of the material passes into the liquid phase, complete melting of metal or metal oxide particles - the entire material passes through the liquid phase. When 3D printing is even within one layer, changing the power of radiation and the speed of processing the surface of the powder layer creates areas of the anode or cathode layer with different densities.

[0134]

[0135] Maximum surface area is required for the anode or cathode of a capacitor. This requires sintering of the powder, as this provides the maximum porosity of the anode or cathode. However, if the powder particles are not in sufficient contact with each other, the mechanical properties of the anodes and cathodes suffer. Mechanical shocks transmitted through the capacitor leads may destroy the anode or cathode. To improve the mechanical properties of the capacitor for a part of tantalum, niobium, or niobium monoxide powder, the 3D printing process provides conditions for metal powder fusion or complete melting. By forming anode or cathode parts with fused or melted powder, capacitor lead or capacitor wire welding areas are formed.

[0135]

[0136] Fig. 13 illustrates the described principle. In one anode or cathode layer, tantalum or niobium metal powders, niobium monoxide powders can be treated by different processes. A portion of the powder undergoes a sintering process and forms a section with a maximum surface area (maximum porosity) 40. Section 40 provides the performance characteristics of the capacitor. In the powder part, a fusion process takes place, and a pore area 41 is formed. Section 41 no longer provides sufficient surface area, but already has sufficient characteristics to withstand mechanical loads. In the powder part, a complete melting process of the metal or metal oxide takes place, and subsequent solidification with the formation of a continuous metal or metal oxide section 42. Section 42 already has a minimum surface area and is not suitable for capacitor performance, but has sufficient mechanical characteristics. The formation of sintering areas 40, fusion areas 41, and full melting areas 42 in the anode and cathode blanks allows for the creation of structures with characteristics sufficient for capacitor operation and resistance to mechanical actions through the capacitor leads.

[0136]

[0137] Fig. 14 demonstrates the principle of forming the lead of a capacitor. The anode or cathode of the capacitor is formed by two sections. The porous section 40 underwent a powder sintering process. The continuous section 42 underwent a process of complete melting or fusion of the powder. To form the capacitor lead, capacitor wire 36 is welded at section 39 to continuous section 42.

[0137]

[0138] Fig. 15 illustrates more complex embodiments with porous and continuous sections. The continuous section 40 and the porous section 42 can have more complex shapes. The shape depends on the 3D printing mode. The continuous section 42 may be an entire anode or cathode layer, a part of the layer, or a part of the layer with a complex cross-section. A part of the continuous section 42 may be unexposed to optical radiation or electron flow to form blind or through holes. The porous section 40 may include internal channels 34. The internal channels 34 are formed during the printing process. A part of the tantalum, niobium, niobium monoxide powder layer may not be exposed to optical radiation or electron flow - a channel is formed in the layer.

[0138]

[0139] Fig. 16 illustrates additional complex embodiments with porous and solid sections. The continuous section 42 has additional branches and stiffening ribs 43 in its construction. The additional branches and stiffening ribs may be formed in the porous section 40 or the porous section 40 with internal channels 34. The shape of the additional branches and stiffening ribs 43 is determined during the design of a particular capacitor model. In different capacitor models, both the internal channels 34 and the additional branches and stiffening ribs 43 may have different shapes. Capacitor wire 36 is welded to form the capacitor lead.

[0139]

[0140] In some cases, the leads of tantalum and niobium capacitors are formed from foil. In the classical technology, a paste with tantalum, niobium, and niobium monoxide particles is spread on the tantalum or niobium foil. Then annealing of the paste polymer composition is carried out.

[0140]

[0141] All of the mentioned 3D printing technologies allow forming an anode or cathode blank on tantalum or niobium foil. It is also possible to use tantalum or niobium foil with removed niobium oxide or tantalum oxide film, with niobium oxide or tantalum oxide film, with polymer coating, coating with deoxidizing metals (e.g., magnesium). After printing, the foil is cut along the contour determined during the development of printing parameters for a certain capacitor model. The processes of 3D printing on tantalum or niobium foil are not different from printing without it.

[0141]

[0142] Before printing, a layer of foil is placed on the building platform. Further printing is carried out on the foil. If necessary, after the printing of the anode and cathode blanks layer is completed, another build platform with a foil layer is placed on the powder surface.

[0142]

[0143] 3D printing of the first layer of anode and cathode blanks is shown in Fig. 17. The building platform 6 is covered with foil 44. During the 3D printing process, the anode and cathode blanks 12 are formed. The process powder 11 gradually fills the space in the build chamber 1 above the building platform 6. In this way, a single layer of anode blanks and cathode blanks 12 is formed when printing on foil is required.

[0143]

[0144] If it is necessary to 3D print the next layer on the foil, an additional building platform 45 covered with a foil layer 46 (Fig.18) is placed on the surface of the process powder 11 in the build chamber 1. Then anode and cathode blanks 47 are printed and a layer of process powder 48 is formed.

[0144]

[0145] The optional build platform may be installed automatically or manually. In some cases, only the foil 46 may be applied to the surface of the process powder 11. For example, if a foil with a thickness of 0.5-1 mm is used.

[0145]

[0146] The building platforms 6 and 45 typically have a rectangular top surface, but round building platforms may also be used if it is possible to deposit tantalum or niobium foil uniformly.

[0146]

[0147] Increase of productivity in the described method of manufacturing anodes, cathodes of electrolytic capacitors, and blanks for them based on tantalum, niobium, niobium monoxide (niobium oxide II) by means of 3D printing technologies can also be achieved by printing anode and cathode blanks in several layers.

[0147]

[0148] Usually, 3D printing of any products is carried out in a single layer of products, but all the described technologies are applicable for printing anodes and cathodes from tantalum, niobium, and niobium monoxide in several layers of products. In this case, the entire building area is used, and build chamber 1 is filled with anode and cathode blanks completely.

[0148]

[0149] Printing options are available where anode and cathode blanks are freely formed during 3D printing. For example, in the case of printing with dry powders, coated powders, powders with lubricants, and paste printing. In other cases, so-called technological supports may be formed to secure the formed anode and cathode blanks. After the 3D printing process is completed, they are removed.

[0149]

[0150] In case technological supports are not used, anode and cathode blanks are printed in several layers (Fig.19). Volume packing depends on the shape of the anode and cathode blanks. When printing without technological supports, the anode and cathode blanks 51 do not touch the build platform 49. Fixation of anode and cathode blanks in space is provided by process powder 50.

[0150]

[0151] In 3D printing using process supports 52, first the process supports 52 are printed on the build platform 49, and then the first layer of anode and cathode blanks 51 is printed (Fig. 20). After the layer of anode and cathode blanks 51 is finished printing, the process supports 52 are printed on their top surface. Then the next layer of anode and cathode blanks 51 is printed on the technological supports 52. Then the process is repeated until the build chamber is filled.

[0151]

[0152] Of the listed 3D printing technologies, printing in several layers of anode and cathode blanks without technological support is impossible only when printing using liquid suspensions.

[0152]

[0153] The increase in productivity is achieved through the use of 3D printing technologies instead of the currently used technologies of pressing and subsequent sintering, or paste deposition technologies and subsequent sintering. The limiting stage in the existing processes is the need to sinter tantalum and niobium powders and niobium monoxide. The sintering process at the used technology requires heating of sintered blanks for anodes and cathodes, holding them at a certain temperature, and subsequent controlled cooling. The process takes place at temperatures in the range of 700-3500°C and requires either batch furnaces or continuous furnaces. The throughput of such furnaces, the efficiency of heat removal systems, and the need for furnace maintenance after several heating and cooling cycles make it difficult to scale up sintering processes. In used furnaces, it is difficult to achieve uniformity of conditions throughout the furnace volume when scaling up. This can lead to different sintering conditions of metal powders in different parts of the furnace and subsequent variation in the characteristics of the produced anodes and cathodes.

[0153]

[0154] In the case of 3D printing technologies, scaling is carried out either by increasing the geometric dimensions of the printing area or by installing several 3D printers in parallel. The 3D printing process itself does not require high temperatures, as heating occurs locally. The energy required for sintering, fusion, and melting is delivered continuously and in small portions. This simplifies heat sinking during the 3D printing of anodes or cathodes. The infrastructure requirements for the capacitor manufacturing plant are reduced. In addition, the printing process is homogeneous throughout the entire build area, which allows for the production of anode and cathode blanks of identical quality.

[0154]

[0155] Impurities have a critical impact on the performance of tantalum and niobium based capacitors and niobium monoxide. Impurities of oxygen, nitrogen, carbon, and other elements can lead to failure of such capacitors. In most cases, when using classical technologies, pressing is carried out in a normal atmosphere (impurities of oxygen and nitrogen), often using lubricants to improve the filling of molds for pressing (carbon contamination).

[0156] If 3D printing is used to produce anode and cathode blanks, contact with the atmosphere can be avoided. The 3D printing process takes place either in an inert atmosphere (argon) or in a vacuum. Metal powders with oxide film previously removed from the surface of the particles can be used. The removal of the oxide film can be accomplished by different technologies, or powder not exposed by air oxygen can be used.

[0155]

[0157] In the case of 3D printing and the different polymer media accompanying the printing process (use of the photopolymerization process, coated powders, use of adhesive binders, lubricants to improve the flowability of the powders), the factors affecting the quality of capacitors are similar. However, it is possible to build anodes or cathodes of much larger size, which provides higher capacitance.

[0156]

[0158] Capacitors based on classical technologies have a homogeneous structure in volume due to the necessity to use the pressing stage. This makes it difficult to access liquid and gaseous process media to the inner areas of anode or cathode when creating a dielectric layer (niobium and tantalum pentaoxides), forming a layer of solid electrolyte (manganese dioxide), forming a layer of polymer electrolyte, access of liquid electrolyte in case of capacitors with high capacitive characteristics. In case magnesium vapor is used for deoxidation of anode and cathode materials, the process of washing blanks from the formed magnesium oxide is also complicated. This reduces the capacitance of the capacitors produced. In some cases, it can lead to capacitor failure.

[0157]

[0159] In the case of 3D printing technologies, it is possible to create internal channels to facilitate access of liquid and gaseous process media to the inner parts of the anode and cathode blanks. If a liquid electrolyte is used in the case of finished capacitors, access of electrolyte to the inner parts of the anode or cathode is ensured.

[0158]

[0160] In classical technology types, due to the use of pressing technology of tantalum, niobium, and niobium monoxide powders, the structure of volumetrically porous anodes and cathodes is homogeneous under all process conditions. In some cases, if the technological process is violated, it is possible to form cavities, areas with a density lower than required.

[0159]

[0161] In the case of 3D printing, the anode or cathode is formed layer by layer. This makes it possible to achieve a uniform density of anodes and cathodes, to control the process of anode or cathode making. If necessary, it is possible to purposefully create areas with reduced density or areas free of metal powder (channels) to provide access to process media during production or liquid electrolyte during operation. If necessary, higher density metal powder regions or solid metal can be targeted to create continuous electrically conductive areas or structures to provide structural strength and rigidity.

[0160]

[0162] In classical capacitor manufacturing techniques for forming capacitor leads, it is common to place tantalum or niobium wire into tantalum, niobium, or niobium monoxide powder before pressing. This complicates the pressing process, and incomplete contact of the capacitor lead with the anode or cathode body may occur. In some cases, when a mechanical load is applied to the capacitor leads due to leverage, the anode or cathode body may be destroyed because the force is transferred to the anode or cathode body. In more recent technology, the capacitor leads are welded to the surface of the anode or cathode. When a mechanical load is applied to the capacitor lead, no load is transferred to the anode or cathode body, although fracture may occur at the point where the capacitor lead is attached to the anode or cathode body. The most current capacitor manufacturing techniques involve placing a paste containing tantalum, niobium, or niobium monoxide powders on a tantalum or niobium foil. However, this technology does not allow forming large (more than 1-2 mm thick) anodes or cathodes of capacitors.

[0161]

[0163] If 3D printing of capacitors is used, it is possible not to use capacitor lead placement during anode or cathode fabrication. The capacitor leads can be welded on later. This applies to the entire group of technologies. When using full metal melting technologies, it is possible to create capacitor leads in the body of the anode or cathode. It is possible to create pads for welding the capacitor leads. It is possible to create leads of complex shape for the distribution of loads in the volume of the anode or cathode of the capacitor. If niobium or tantalum foil is used to create capacitor leads, it is possible to 3D print blanks for capacitor anodes or cathodes directly on the foil. The capacitor leads can be welded, if necessary, at the next stages of production.

[0162]

[0164] Current manufacturing techniques for tantalum and niobium capacitors require long annealing times at temperatures up to 3000°C. Peak energy consumption and heat sinking occur. This complicates the infrastructure of the plants.

[0163]

[0165] In the case of the entire group of 3D printing technologies, energy consumption and heat sinking are spread out over time. Energy is supplied continuously and in small quantities. It can be laser radiation for sintering, fusion, melting of metal powder, laser radiation for the photopolymerization process, electron beam in the case of an electron gun, or heat radiation to ensure solidification of the polymer component. Similarly, heat sinking is carried out. If it is necessary to use high-temperature furnaces for annealing of polymer components or additional sintering of anode or cathode blanks, the time spent in the furnaces is reduced, and the energy consumption is also reduced. As a result, infrastructure costs are reduced, peak energy consumption and heat sinking are eliminated.

[0164]

[0166] The 3D printing processes themselves provide less variation in the characteristics of the finished products. Currently, classical technologies produce up to 50% of defective tantalum and niobium capacitors due to heterogeneous conditions in the process equipment. 3D printing processes reduce the defect rate to 5-30%.

[0167] In classical tantalum and niobium capacitor production technologies, it is necessary to exclude contact of anode and cathode blanks with air oxygen during cooling from the sintering temperature to normal conditions. Contact with oxygen causes the uncontrolled oxidation of metals to their oxides. Tantalum and niobium oxides act as dielectrics in the finished capacitors and exist in amorphous form. Uncontrolled growth of the oxide film may result in the appearance of crystalline phases of these oxides, which may lead to failure of the capacitors or shorten the lifetime of such capacitors. In some cases, uncontrolled heating of anode and cathode blanks occurs, which may lead to their complete destruction.

[0165]

[0168] When 3D printing is used to produce blanks and anodes, localized heating in an inert atmosphere takes place. At the end of the printing process, all blanks are already at a temperature comparable to normal conditions, and uncontrolled oxidation does not occur. If annealing is necessary in the case of polymer binders, uncontrolled oxidation is only possible if the annealing conditions are not correct.

[0166]

[0169] Classical technologies of tantalum and niobium capacitor production are limited by the shape and size of anodes and cathodes. Pressing and subsequent annealing technologies allow for obtaining only simple shapes of anodes and cathodes. Usually it is a rectangular parallelepiped, cylinder, or hollow cylinder (not less than 0.5-1 mm). In case of paste application with tantalum, niobium, and niobium monoxide and subsequent annealing, anodes and cathodes have the form of thin plates (not more than 1-2 mm). Both variants allow to creation of only continuous forms.

[0167]

[0170] In the case of 3D printing, it is possible to overcome these limitations. When printing without polymer binders, it is possible to create anodes with dimensions less than 0.5 mm. When printing with polymer binder, it is possible to create large anodes with dimensions up to several cm along all axes (50-100 mm). It is possible to create more complex shapes, internal channels, and cavities.

[0168] INDUSTRIAL APPLICABILITY

[0169]

[0171] The present invention is suitable for the manufacture of anode and cathode blanks, anodes and cathodes themselves made of metallic tantalum (Ta) or niobium (Nb), niobium monoxide (NbO), mixtures thereof. Such anodes and cathodes are used to manufacture electrolytic capacitors based on the mentioned materials. Such capacitors are used in aerospace equipment, medical equipment, electronic equipment (especially in mobile devices), automobile electronics, and special-purpose equipment.

Claims

ClaimsWhat is claimed is:

1. A method of manufacturing anodes, cathodes of electrolytic capacitors and blanks for them based on tantalum, niobium, niobium monoxide (niobium oxide II) by using 3D printing technologies, comprising spreading a layer of metal powder or metal oxide or paste or suspension containing particles of metal powder or metal oxide on a building platform, forming a layer of a desired product or a group of products, wherein the process of forming a desired product or a group of products in the presence of a light source: when dry powders are used for manufacturing the product or group of products using sintering, fusing, or melting technologies, the process is carried out using optical radiation; when dry powders are used to manufacture a desired product or group of products and a polymeric binder is used, the layer of the product or products is formed by printing with a polymeric binder that permeates the powder at selected points, then the polymeric binder is either allowed to cure on its own, or the polymeric binder is exposed to heat, or the polymeric binder, if the composition used is capable of photopolymerization, is exposed to optical radiation at the photopolymerization wavelength of the composition used; when pastes or suspensions with metal powders or metal oxide powders are used to manufacture the product or group of products, the layer of the product or products and the photopolymerization ability of the dispersion medium composition are exposed to light at the photopolymerization wavelength of the selected composition; the building platform is moved downwards by the height of the formed layer; the above steps are repeated until the product is completely formed.

2. The method according to claim 1, wherein dry powders are used to manufacture a product or group of products and sintering, fusing, or melting technologies are used, the process is carried out using laser radiation.

3. The method according to claim 1, wherein dry powders are used to manufacture the product or group of products and sintering, fusing, and melting technologies are used, the process is carried out using a beam of electrons generated by an electron gun.

4. The method according to claim 1, wherein dry powders are used to manufacture a product or group of products and a polymeric binder is used, the layer of the product or productsis formed by printing with a polymeric binder that permeates the powder at selected points, then the polymeric binder is either allowed to cure on its own, or the polymeric binder is exposed to heat, or the polymeric binder, in the case of the photopolymerization ability of the composition to be used, exposed to laser radiation at the photopolymerization wavelength of the composition to be used at selected areas.

5. The method according to any of claims 1-4, wherein a laser beam, other optical radiation source, or electron beam is point by point or continuously moved across the surface of the sprayed powder or paste to form a single layer of the product or products.

6. The method according to any of claims 1-4, wherein to form a single layer of the product or products, the laser beam, another optical light source, or a large-area illuminated electron beam treats the surfaces of the powder, paste, or slurry section by section.

7. The method according to any of claims 1-4, wherein one layer of a product or products, the laser beam, another optical radiation source, or electron beam forms a radiation spot on the surface of the product that is identical in shape to the shape of the anode or cathode layer.

8. The method according to any of claims 1 -4, wherein for forming one layer of products, the laser beam, another optical radiation source, or electron beam forms a radiation spot on the surface of the workpieces whose shape coincides with some or all of the cross sections of the anodes and cathodes at once.

9. The method according to claim 1, wherein of carrying out the process, the print head is moved above a build area with a layer of metal powder or metal oxide (tantalum and niobium), drops of polymer binder are deposited at a place where layers of anode blanks or cathode blanks are formed, the formed layers of anode blanks and cathode blanks are arranged on the build platform, printed anode and cathode blanks are surrounded by process powder, drops of polymer binder wet the powder layer in the place of formation of the future layer of anode and cathode blanks, moving light source is moved over the wetted polymer binder, under the influence of radiation the next layers of anode or cathode blanks are formed.

10. The method according to claim 1, wherein a light source is used, the polymer binder- wetted areas are exposed to radiation, wherein portions of the surface of the printing area are illuminated.

11. The method according to claim 1, wherein the gas process medium in which the 3D printing process takes place may be a vacuum or various gases and mixtures thereof.

12. The method according to claim 1, wherein a foil layer is applied to the build platform before printing.

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