Showing papers on "Tantalum capacitor published in 2019"

Hydrometallurgical Process for Tantalum Recovery from Epoxy-Coated Solid Electrolyte Tantalum Capacitors.

Abstract: Tantalum is a critical metal that is widely used in electronic products. The demand for tantalum is increasing, but the supply is limited. As tantalum waste products have increased in Taiwan in recent years, the treatment of spent tantalum capacitors has become necessary and important. The recycling of tantalum from tantalum capacitors will not only decrease pollution from waste, but will also conserve tantalum resources. The tantalum content in epoxy-coated solid electrolyte tantalum capacitors (EcSETCs) is over 40 wt.%. Here, we designed a recycling process that includes pre-treatment, leaching, and solvent extraction to recover tantalum. In the pre-treatment process, epoxy resin and wires were removed. During hydrometallurgical process, pressure leaching by hydrofluoric acid was used to leach tantalum and manganese from solid electrolyte tantalum capacitors (SETCs). During our testing of this proposed process, the acid concentration, reaction time, temperature, and solid–liquid ratio were examined for leaching. After the leaching process, Alamine 336 was used to extract tantalum from the leaching solution. The pH value, extractant concentration, extraction time, and aqueous–organic ratio were investigated. Then, tantalum was stripped using HNO3, and the HNO3 concentration, stripping time, and organic–aqueous ratio were analyzed in detail. Under optimal conditions, the recovery efficiency of tantalum reached over 98%, and a final product of tantalum pentoxide with 99.9% purity was obtained after chemical precipitation and calcination.

Poole–Frenkel Emission Saturation and Its Effects on Time-to-Failure in Ta-Ta2O5-MnO2 Capacitors

Abstract: I-V characterization of Ta-Ta2O5-MnO2 capacitors was investigated at different temperatures, and Poole–Frenkel (PF) emission saturation was experimentally observed. Under the saturation voltage, the I-V curves at different temperature converged, and the temperature dependency was vanished. Above the saturation voltage, the leakage current was decreasing as the temperature increased. In order to evaluate the effects of saturation voltages (VS) on time-to-failure (TTF) of the capacitors, VS were first determined at +2°C and +25°C, then voltage accelerating tests were conducted at 85°C under 1.6 times of rated voltage. The distribution of VS and TTF of the samples were plotted and compared. It was shown that samples with lower saturation voltage failed earlier in the distribution of time-dependent dielectric breakdown. Comparing conventional methods for evaluating the quality of tantalum capacitors by measuring the leakage current at elevated temperature, the nondestructive measurement of saturation voltage at +2°C and +25°C may provide a novel and practicing approach tool to screening out capacitors with defected Ta2O5 layers.

Non-electrolyte tantalum electrolytic capacitor positive and negative electrode patch welding process

Abstract: The invention provides a non-electrolyte tantalum electrolytic capacitor positive and negative electrode patch welding process. According to the process, a positive lead and a negative lead of the electrolytic capacitor are completely removed; and then the positive and negative patches are fixed on the positive and negative ends of the electrolytic capacitor through electrolytic capacitor plasma ball welding, electrolytic capacitor patch spot welding and electrolytic capacitor patch full welding, so that the non-electrolytic tantalum electrolytic capacitor with the positive and negative patchfixed structure is obtained. The fixed structure of the positive and negative patches is obtained by adopting the process disclosed by the invention, so that the contact area of the product and a circuit board is increased when the product is welded. The mechanical strength of the product in the use process is increased, and the use reliability of the product in the structure is ensured. Operationis convenient, the production efficiency can be greatly improved, and the product percent of pass is increased.

Effect of Moisture on AC Characteristics of Chip Polymer Tantalum Capacitors

Abstract: Contrary to conventional tantalum capacitors with MnO2 cathodes, chip polymer tantalum capacitors (CPTCs) might degrade in both high humidity and dry environments. A better understanding of the kinetics of moisture content variations in CPTCs is necessary to determine bake-out conditions for the parts before soldering to avoid pop-corning failures and to select adequate preconditioning before reliability and qualification testing. In this paper, ac characteristics in different types of CPTCs have been studied with time during moisture sorption and desorption at temperatures from room to 125 °C. Capacitance increased with moisture content from minimal to maximal values reproducibly. This allowed using tantalum slugs as humidity sensors and measurements of capacitance variations with time to describe processes of moisture diffusion. A model that relates characteristic times of capacitance variations with the size of the case and moisture characteristics of polymer materials has been developed. Temperature dependencies of the characteristic times follow Arrhenius law with activation energy in the range from 0.4 to 0.5 eV. The equivalent series resistance (ESR) remained relatively stable during environmental testing, but dissipation factors (DFs), reached maximum and increased more than 10 times at characteristic times of moisture accumulation or release. The phenomena have been explained by changes in the charge absorption processes caused by variations of the barrier at the conductive polymer/Ta2O5 interface with moisture content.

Extraction Potential of Tantalum from Spent Capacitors Through Bioleaching

Abstract: Tantalum (Ta) is the one of the most critical elements according to the European Commission. Research on tantalum recovery from secondary sources such as waste electrical and electronic equipment (WEEE), bottom ash and by products of the industrial activities, however, is limited. In this study, the recovery potential of tantalum from spent tantalum capacitors was tested using bioleaching. Three different kinds of microorganisms were tested for tantalum recovery, which were Pseudomonas putida (DSM No. 6125), Bacillus subtilis (DSM No. 1088532), and Penicillium simplicissimum (DSM No. 1078). It turned out that P. simplicissimum has the ability to leach tantalum from wasted tantalum capacitors with a maximium leaching rate of 1.25 g Ta per kg sample. An unknown species achieved the highest leaching rate (9.88 g Ta / kg sample) but isolation and identification failed. The potential of tantalum recovery by bioleaching is demonstrated, however, further research needs to be carried out.

3-D Packaging and Integration of High-Density Tantalum Capacitors on Silicon

Abstract: High-density, point-of-load (PoL) power conversion and power delivery are required to continue scaling electronic systems with increased functionality, more bandwidth, and smaller sizes. To meet the demands of these highly complex and miniaturized electronic systems, new 3-D integration schemes of advanced passive and active components are needed to enable the next-generation power distribution networks (PDNs). In addition, shorter interconnect lengths are required to provide low losses and better transient response in switch-based power conversion systems. Tantalum capacitors have the potential to provide some of the highest volumetric densities of any current capacitor technology, but are generally bulky components with low frequency stability, limiting their use in future 3-D power systems. In this paper, a process for the embedding and integration of ultrathin, high-density tantalum capacitors with improved frequency stability is demonstrated. The 5-V capacitors show a density of $1~\mu \text{F}$ /mm2 at 1 MHz with only a 100- $\mu \text{m}$ thickness, and are shown to be capable of direct integration on silicon for short interconnect length of $ . The electrical performance of the capacitors is tested after integration and shows that they retain high capacitance density and low equivalent series resistance (ESR), while also providing low leakage currents. The combination of low loss, high volumetric density, and 3-D integration capability make the capacitors an ideal candidate for next-generation power modules.

Chip tantalum electrolytic capacitor test fixture

Abstract: The invention relates to the technical field of tantalum electrolytic capacitors and discloses a chip tantalum electrolytic capacitor test fixture, which comprises an upper mold plate, a middle mold plate, a lower mold plate, negative pressure pins, an insulating base, a positive pressure pin, a circuit board, a hydraulic oil cylinder, a pressure pin positioning plate and a positive pressure pin panel. A plurality of buffer grooves are formed in the lower surface of the middle mold plate; the negative pressure pins are in sliding connection with the groove walls of the buffer grooves; a telescopic rod is fixedly connected to the upper end of each negative pressure pin; a first piston is fixedly connected to the upper end of each telescopic rod; a compression spring is fixedly connected between each first piston and the corresponding negative pressure pin; each compression spring movably sleeves the rod wall of the corresponding telescopic rod; two sliding grooves are symmetrically formed in the groove wall of each buffer groove, and second pistons are slidably connected into the sliding grooves. The chip tantalum electrolytic capacitor test fixture can perform multi-stage bufferingon negative pressing pins, prevents the negative pressing pins from damaging circuit boards and effectively reduces the abrasion of guide pillars and guide sleeves; the service life of the fixture isprolonged.

Low-ESR cathode of tantalum electrolytic capacitor and preparation method for cathode

Abstract: The invention relates to a low-ESR cathode of a low-ESR tantalum electrolytic capacitor and a preparation method for the cathode, and relates to the technical field of tantalum capacitor manufacturing. The preparation method comprises the steps: preparing a manganese dioxide layer on the surface of a tantalum block with a dielectric oxidation film, wherein the manganese dioxide layer is prepared through a method which comprises the steps: performing the dipping of the tantalum block in manganese nitrate solution with different specific gravities for many times, performing the thermal decomposition to obtain a first cathode, performing the dipping of the first cathode in outer mixed solution, performing the decomposition for many times under the temperature from 250 DEG C to 280 DEG C, performing the reinforcement processing, and performing the dipping and thermal decomposition in the outer mixed solution to obtain the electrode, wherein the outer mixed solution is prepared through adding a dispersing agent and a viscosity reducer to the manganese nitrate solution. The method enables the surface of the tantalum block to form compact manganese dioxide shaped like popcorn, thereby completing the manufacturing of the low-ESR electrode, and improving the high-frequency electrical performance of the tantalum electrolytic capacitor.

Circular electrolyte tantalum capacitor polishing and grinding machine that goes between

Abstract: The utility model provides a circular electrolyte tantalum capacitor polishing and grinding machine that goes between, circular electrolyte tantalum capacitor polishing and grinding machine that goesbetween includes: the device body, the device body is still including handheld handle, hold axle and handle, handheld handle is fixed at device body right -hand member, be adapted to polishing and grinding machine technical field's production and application, this kind of circular electrolyte tantalum capacitor polishing and grinding machine that goes between, first use person can be with externalconnector assembly to power department, then start centrifugal fan, as the user when carrying out polishing treatment to the material, centrifugal fan will be through the powder of the cooling in theconnecting pipe suction top box, then the cooling powder is with in the suction centrifugal fan, it will discharge through the pipeline to cool off the powder after that, and cool off polishing and grinding machine, this kind of circular electrolyte tantalum capacitor polishing and grinding machine that goes between's practicality has been promoted, the problem of current circular electrolyte tantalum capacitor polishing and grinding machine that goes between produce high temperature damage easily when using is solved.

Nonpolar tantalum capacitor

Abstract: The invention discloses a nonpolar tantalum capacitor. The nonpolar tantalum capacitor comprises an installation block; an installation hole is fixed in the middle of the installation block; a first contact slides in the installation hole; a first sliding block is fixedly on the end part of the lower end of the first contact; a first spring is arranged at the lower end of the first sliding block;a baffle is arranged at the lower end of the first spring; the baffle is fixed at the bottom of the installation block; a second contact is tightly contacted with the upper end of the first contact; the tantalum capacitor is fixed on the upper end of the second contact; an installation rod is in sleeved connection outside the second contact; the installation rod is fixed on the lower end of the tantalum capacitor; and a locking mechanism is arranged between the installation rod and the installation block. By means of the structure, the tantalum capacitor is high in withstand voltage value, good in electrical property, steady, reliable, long in service life, low in loss and electric leakage, high in security performance, convenient to assemble and disassemble, simple in structure, easy to operate and high in working efficiency.

Dissolution of manganese (IV) oxide from tantalum capacitor scrap by organic acids

Abstract: The dissolution of MnO2 from tantalum capacitor scrap using organic acids in various process conditions was studied. The initial materials were of two types: LTC (leaded tantalum capacitors) and SMDTC (surface-mounted device tantalum capacitors). The research materials were prepared by pyrolysis, grinding and sieving and the preparation processes were characterized. Dissolution of MnO2 was carried out with the use of sulfuric acid solutions with the addition of acetic, ascorbic, citric and oxalic organic acids. Results show that the addition of organic acids significantly improves dissolution yields (72-94 vs 90-99 % for H2SO4 and acid mixtures, respectively). In practice, a concentration of organic acid above 1 M results in the complete removal of MnO2.

Degradation of ESR in Polymer Tantalum Capacitors During High Temperature Storage

Abstract: Replacement of MnO2 cathodes with conductive polymers in chip tantalum capacitors allows for a substantial reduction of the equivalent series resistance (ESR), improvement of frequency characteristics, and elimination of the possibility of ignition during failures. One of the drawbacks of chip polymer tantalum capacitors (CPTCs) is a relatively poor long-term stability at high temperatures. Due to degradation processes in conductive polymer materials, the existing quality assurance testing that has been developed for MnO2 capacitors is not sufficient to guarantee long-term stability of CPTCs. Insertion of CPTCs in hi-rel systems requires development of models that can predict degradation of the parts at operating conditions. In this work, variations of AC characteristics (capacitance, DF and ESR) in different types of capacitors from three manufacturers have been monitored during storage at temperatures from 100oC to 175oC for periods of up to 15,000 hours. Results show that the most sensitive to degradation parameter is ESR. Distributions of times to parametric failure during storage have been simulated using a Weibull-Arrhenius model that allowed for assessments of activation energies of degradation and prediction of times to failure at use temperatures. Mechanisms of degradation and the effect of packaging are discussed.

High-energy composite tantalum electrolytic capacitor

Abstract: The utility model provides a high-energy composite tantalum electrolytic capacitor. The tantalum electrolytic capacitor comprises two cathode sheets and an anode tantalum block arranged between the two cathode sheets in an insulating manner, the anode tantalum block comprises a cake-shaped tantalum block body and a groove formed in the center of the upper end face of the tantalum block body. The area of the groove is 0.5%-50% of the area of the upper end surface; the depth of the groove is 5-40% of the thickness of the tantalum block body; and a first circular hole and a plurality of second circular holes are formed in the cathode piece, the first circular hole is formed in the center of the cathode piece and is concentric with the groove, the plurality of second circular holes are formedaround the circumference of the first circular hole at equal intervals, and the total area of the first circular hole and the second circular holes is 0.08%-2.00% of the area of the cathode piece. According to the utility model, the space utilization rate, the capacitance and the cathode utilization rate are effectively improved, and the ESR value is reduced.

Tantalum core for chip tantalum capacitor, preparation method of cathode of tantalum core for chip tantalum capacitor and chip tantalum capacitor

Abstract: The invention discloses a tantalum core for a chip tantalum capacitor, a preparation method of a cathode of the chip tantalum capacitor and the chip tantalum capacitor. The preparation method of the cathode of the chip tantalum capacitor comprises the steps of: preparing 4-8 groups of manganese nitrate solution with proportions of 1.0-2.3 g/cm3, and adding a nonionic surfactant in the manganese nitrate solution with proportions of 1.0-2.3 g/cm3, wherein the groups of manganese nitrate solution have different proportions; and continuously steeping an anode tantalum core in each group of manganese nitrate solution for 1-5 times, and after the steeping at each time, immediately carrying out high-temperature moisture thermal decomposition on the steeped tantalum core so as to form a hollow manganese dioxide cathode layer. According to the tantalum core, prepared by the preparation method, for the chip tantalum capacitor, the cathode layer with a hollow manganese dioxide cathode layer is formed, so that benefit is brought to improve the stability and reliability of the tantalum core for the chip tantalum capacitor, and the tantalum core for the chip tantalum capacitor has ultralow equivalent serial resistance (ESR).

Non-solid electrolyte tantalum capacitor working electrolyte and preparation method thereof, and non-solid electrolyte tantalum capacitor

Abstract: The invention discloses a non-solid electrolyte tantalum capacitor working electrolyte and a preparation method thereof and a non-solid electrolyte tantalum capacitor; the preparation method of the working electrolyte comprises the following steps of (1) preparing a sulfuric acid solution with the mass percent concentration of 35-45%; and (2) adding an organic supramolecular compound containing anelectron-rich group and silica sol into the sulfuric acid solution with the mass percent concentration of 35-45%, and carrying out uniform mixing. According to the non-solid electrolyte tantalum capacitor working electrolyte, due to the fact that the organic supramolecular compound containing the electron-rich group is added, metal cations and other electron-deficient ions, such as Ag+ and the like, can be directly bonded in a power-on state; and therefore, when the non-solid electrolyte tantalum capacitor packaged by a silver shell adopts the working electrolyte, a phenomenon that Ag+ is transferred to a tantalum core due to reverse influence is blocked in the using process, and the service life of the non-solid electrolyte tantalum capacitor packaged by the silver shell is effectively prolonged.

Macromolecule tantalum capacitor

Abstract: The invention discloses a macromolecule tantalum capacitor. The macromolecule tantalum capacitor comprises a tantalum capacitance block, a medium layer is wrapped on the outside of the tantalum capacitance block, a conductive layer is wrapped on an outside of the medium layer, a graphite layer is wrapped on the outside of the conductive layer, and a silver-plating layer is wrapped on the outside of the graphite layer; a cathode leading sheet is adhered at an upper end of one side of the silver-plating layer through a conductive adhesive, one end, far away from the silver-plating layer, of thecathode leading sheet is electrically connected with a cathode; one end, far away from the cathode leading sheet, of the tantalum capacitance block is electrically connected with a lead wire, the leadwire orderly penetrates the medium layer, the conductive layer, the graphite layer and the silver-plating layer; one end, far away from the tantalum capacitance block, of the wire lead is electrically connected with an anode, and a package layer is wrapped on the outside of the silver-plating layer. Through the above structure, the impedance and ESR are small in change at the high frequency bandwhen a capacitor is in an ultra-low high-frequency environment or has an ultra-low equivalent series resistance, the high-frequency noise reduction and high-frequency capacity maintenance can be effectively reached.

Method for improving voltage withstanding ability of tantalum capacitor and method for manufacturing tantalum capacitor

Abstract: The invention provides a method for improving the voltage withstanding ability of a tantalum capacitor and a method for manufacturing a tantalum capacitor, and relates to the field of electronic devices. The method provided by the invention for improving the voltage withstand of a tantalum capacitor comprises the steps of providing a tantalum block used for forming a tantalum capacitor; impregnating the tantalum block in an alkaline test solution at a preset temperature; applying voltage and current with preset parameters to the tantalum block impregnated in the alkaline test solution, and forming a first dielectric oxide film on the surface of the tantalum block. The surface of the tantalum block is additionally provided with the dielectric oxide film in the case of not changing the shapeand size of the tantalum capacitor, thereby increasing the thickness of an dielectric layer of the tantalum capacitor, and improving the voltage withstanding ability of the tantalum capacitor.

Manufacturing method for anode tantalum block of non-solid electrolyte tantalum capacitor

Abstract: The invention discloses a manufacturing method for an anode tantalum block of a non-solid electrolyte tantalum capacitor. The manufacturing method comprises the following steps: (1) selecting tantalumpowder used for forming the anode tantalum block; (2) carrying out powder mixing and compression molding on a binding agent used for the tantalum powder; (3) putting the formed anode tantalum block in a presintering furnace for presintering, wherein the presintering temperature is 100+/-20 to 300+/-20 DEG C, and the presintering time is 30+/-10 to 120+/-10 min; and (4) carrying out sintering according to requirements, wherein the sintering temperature is 1200+/-20 to 2050+/-20 DEG C, and the sintering time is 20+/-10 to 60+/-10 min. According to the manufacturing method, under the condition that effective removal of the binding agent is met by the anode tantalum block, the presintering temperature of the anode tantalum block is changed, the oxygen content of the presintered anode tantalumblock is reduced, and the anode tantalum block manufactured through the method can reduce the leakage current value after the non-solid electrolyte tantalum capacitor is formed.

Manufacturing process of tantalum core of high-temperature all-tantalum capacitor

Abstract: The invention discloses a manufacturing process of a tantalum core of a high-temperature all-tantalum capacitor. The process specifically comprises the following steps that (1) a tantalum core formingdie is selected, wherein a convex die with a convex chamfer on the circumferential edge is adopted as a lower convex die of the forming die; (2) a tantalum core rough blank is manufactured by adopting alcohol die removal through cold isostatic pressing forming; and (3) the upper end of a tantalum wire of the tantalum core rough blank is made into a bent hook to be hung on a tantalum wire net, then the tantalum core rough blank is placed in a tantalum cylinder, and suspension sintering is carried out in a vacuum indirect heating mode to prepare the tantalum core of the high-temperature all-tantalum capacitor. According to the manufacturing process of the tantalum core of the high-temperature all-tantalum capacitor, the obtained tantalum core is excellent in quality, high in production efficiency, low in cost, simple in process, convenient to operate and extremely high in market application and popularization value.

Method for reducing carbon and oxygen content of sintered tantalum block of tantalum capacitor

Abstract: The invention relates to the technical field of tantalum capacitor manufacturing, in particular to a method for reducing the carbon and oxygen content of a sintered tantalum block of a tantalum capacitor. By means of powder mixing, airing, forming, binder removing and sintering treatment, the carbon and oxygen content of the tantalum capacitor is effectively reduced, and therefore the purity of the sintered tantalum block is improved. Compared with a traditional process, the carbon and oxygen content of the prepared tantalum capacitor is reduced by 10% to 90%, meanwhile, the leak current of the tantalum capacitor product is reduced, and the production yield, electrical performance and reliability of the tantalum capacitor are ensured.

Method for reducing leakage current of PEDOT solid tantalum capacitor

Abstract: The invention discloses a method for reducing leakage current of a PEDOT solid tantalum capacitor. The method comprises the steps of immersing a tantalum core in a butyl titanate ethanol solution, forming a thin TiO2 film on the inner and outer surfaces of a dielectric layer through hydrolysis of butyl titanate, and then forming a PEDOT conductive film on the surface of the TiO2 film by adopting an in-situ method. Oxidants, monomers and by-products reside in the tantalum core during the in-situ polymerization process, which causes damage to the dielectric layer. According to the invention, thedamage of the in-situ polymerization method to the dielectric layer is improved through introducing the TiO2 film between the dielectric layer and a Ta2O5 film, and the PEDOT solid tantalum capacitorwith low leakage current is prepared.