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Replacement of MnO2 with conductive polymers as cathode materials 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. In this work, variations of capacitance, dissipation factor, and ESR in different types of capacitors including automotive grade parts from three manufacturers have been monitored during storage at temperatures from 100 °C to 175 °C for up to 18,000 hours. Results show that ESR is the most and capacitance the least sensitive to degradation parameter. Times to parametric failures have been simulated using a Weibull-Arrhenius model that allowed for assessments of activation energies of the degradation and prediction of times to failure at the use temperature. Degradation of CPTCs was explained by thermo-oxidative processes in conductive polymers that result in exponential increasing of the resistivity with time of ageing. This process starts after a certain incubation period that depends on packaging materials and design and corresponds to the time that is necessary to form delamination between the encapsulating molding compound and lead frame. The effectiveness of the existing qualification procedures to assure stable operation of CPTCs is discussed.

In this work, different types of polymer and MnO 2 cathode capacitors are tested for scintillation breakdown using a constant current stress (CCS) technique modified to allow detection of amplitudes and duration of current spikes. Monitoring of leakage currents with time under bias is used to assess the effect of scintillations. The appearance and composition of damaged sites are examined after deprocessing and cross-sectioning. Thermal processes during scintillations are analyzed, a mechanism of breakdown based on growth of conductive filaments in the dielectric is suggested, and self-healing processes in polymer and MnO 2 cathode capacitors is discussed.

Popcorning is a well-known effect in plastic encapsulated microcircuits (PEM) and it occurs in chip tantalum capacitors. The sensitivity of components to the presence of moisture during soldering is characterized by the moisture sensitivity level (MSL); however, contrary to PEMs, there is no standard procedure for establishing MSL for tantalum capacitors. The effect of absorbed moisture on soldering related degradation and failures in tantalum capacitors have not been studied properly yet, and there is no sufficient information regarding the difference in the sensitivity to soldering between polymer and MnO2 capacitors. In this work, 16 types of polymer and 9 types of MnO2 tantalum capacitors with different moisture content have been tested before and after reflow soldering. The level of moisture release during soldering has been estimated and thermo-mechanical analysis used to assess deformation of capacitors during soldering simulations. Results show that moisture uptake in similar parts is approximately two times greater in polymer than in MnO2 capacitors. Cracking of the case and degradation of parameters can occur in both types of parts, but MnO2 capacitors are much more likely to fail catastrophically with a short circuit and possible ignition during the first power-on cycle. This type of failure in MnO2 capacitors is lot-related, can occur even at derated voltages and relatively low levels of moisture sorption that corresponds to room conditions. Baking before soldering is an effective measure to prevent failures even in lots susceptible to popcorning damage.

The automization complex device SOLARTRON-1280C was used for measurement electrical parameters of the industrial tantalum electrolytic capacitors. It was shown that the method for detection of the defective products is applied to constant current mode and impedance measurements. The impedance measurements was used for determination of the electric capacity tantalum capacitors and how it depends on the aperiodic current frequency. In addition impedance method is able to indicates on the secondary processes that occurs in the capacitor when it works in electric circuit. The general parameters of the tantalum capacitors in direct current were determined by polarization methods.

Printed Circuit Boards (PCB), secondary source of critical metals, are usually recycled to recover precious metals. Alternative routes, aiming to pre-concentrate critical metals, were tested at lab scale. An up-scaling process is proposed involving a thermomechanical separation of PCB and surface mounted devices (SMD). PCB without SMD are treated by solvolysis for desilication and debromination. Further calcination provides a presumably leachable metallic mix. Tantalum capacitors, a specific type of SMD, are treated by pyrolysis, to isolate metallic cores, which are further leached to obtain 92% pure tantalum oxide. LCA data show that tantalum recycling process is profitable for the environment.

Because of the low concentrations of Tantalum on printed wiring boards, today it is not economically viable to recycle Tantalum in pyro- and hydrometallurgical processes. However, in case the Tantalum can be up concentrated, the recycling of the Tantalum can become economically viable in the multi-stage process used to refine Tantalum from ores. Therefore, the presented research investigates the techno-economic potential of selectively removing Tantalum capacitors from PWBs prior to treating the complete PWBs in integrated precious metal smelting and refining installations. In the presented research the economic potential is analysed using return on investment analysis for automated selective dismantling and the viability of manual selective dismantling. These analyses are based on the measured metal concentration of Tantalum capacitors, the composition of a typical PWB and the results of lab experiments for the removal and detection of components using deep learning computer vision.

The basic bilayer of all types of tantalum capacitors, tantalum anode, and anodic oxide film of tantalum as a dielectric is not a thermodynamically stable system. This is demonstrated by the tantalum-oxygen equilibrium diagram that does not contain two-phase equilibrium areas for pure tantalum and tantalum pentoxide]. Relaxation of the Ta-Ta2O5 system into the thermodynamically stable state occurs through oxygen migration from Ta2O5 to Ta, resulting in oxygen vacancies in the tantalum oxide dielectric. Conductivity of the dielectric and, thereby, DCL of tantalum capacitor increase exponentially with the concentration x of oxygen vacancies in the depleted with oxygen Ta2O5–x. Another reason for the thermodynamic instability of tantalum capacitors is the amorphous structure of the anodic oxide film of tantalum formed on crystalline tantalum. Amorphous dielectrics trend to ordering and crystallization spontaneously to reduce their internal energy. Growth of crystalline inclusions in amorphous matrix of the anodic oxide film induces mechanical stress in the film, which results in a disruption of the dielectric and, thereby, in the failure of the capacitor.

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.

Three types of Al/MoO3 energetic semiconductor bridge (ESCB) initiators were prepared by integrating Al/MoO3 reactive multilayer films (RMFs) of different stoichiometric ratios on semiconductor bridges through magnetron sputtering. The stoichiometric ratios of Al:MoO3 were 4:1, 2:1, and 4:3. An experimental investigation for obtaining the electrical explosive characteristics of the ESCBs with different stoichiometric ratios of Al/MoO3 RMFs was carried out under the stimulation of a 47 μF tantalum capacitor discharge. The results reveal a ‘stagflation’ phenomenon in the voltage–current–resistance curves of the ESCBs, which is obvious at low discharge voltages. The critical burst energy and critical burst time decrease with an increase in the MoO3 ratio in RMFs for initiators discharged with identical voltages. Moreover, among the three ESCBs, the one with a stoichiometric ratio of 4:3 exhibits the highest performance with the shortest critical burst time, lowest critical burst energy, and most violent explosion phenomenon. This suggests that the ignition performance of ESCBs can be enhanced by optimising the stoichiometric ratio of Al/MoO3 RMFs.

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.

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.

Micro supercapacitor (MSC) featured by high capacitance density, has great potential for replacing bulky electrolytic capacitors in circuits to make electronics of miniaturization, yet suffers from sharp capacitance drop under alternating current. Here, we report a circuit-integratable high-frequency MSC with hybrid architecture electrode, in which 2D pseudocapacitive MXene served as the active material provides large capacitance and multi-walled carbon nanotube applied as interlayer support offers fast ion transport paths. Such design brings the device an excellent frequency response and a capacitance density much higher than commercial tantalum capacitors at 120 Hz. A novel transfer-free filtration technology greatly eliminates the equivalent series resistance and the consequent thermal loss, and makes the MSC a more circuit-integratable planar geometry. Moreover, such high-frequency MSC is applied in a low-pass filtering circuit and a relaxation oscillator circuit, displaying advantages in function, size and intergratability compared with electrolytic capacitors.

Despite increasing pressure to reduce the consumption of critical resources, a number of highly relevant elements are still not being recycled from electronics, or only in the few applications, where they are used in bigger units. In high volume products and particular mobile products such as smartphones the content of these materials is low per unit, but still a large quantity when multiplied with millions of units shipped per year. The sustainably SMART projects explores the option to separate components containing tantalum, neodymium and tungsten from disassembled smartphones as these metals are lost in conventional electronics waste recycling processes. In this paper the target components are tantalum capacitors, loudspeakers, and vibration motors. Example quantities per device are explored and mirrored against current and potential recycling processes.

Electronics subsystems play an increasingly important role in safety critical systems for monitoring, control, and enhanced functionality. Electrolytic capacitors are an important component in ,amy subsystems that range from power supplies on safety critical avionics equipment to power drivers for electro-mechanical actuators. These capacitors are ideal forpassing or bypassing low-frequency signals in power supplies but are known to have lower reliability compared to ceramic and tantalum capacitors, and given their criticality in electronicssubsystems they are a good candidate for component level monitoring and prognostics. Prognostics provides a way to assess remaining useful life of components and systems based on their current state of health and their anticipated future use and operating conditions. Past experiences have shown that capacitor degradation and failures are quite prevalent under high electrical and thermal stress conditions that they experience during operations. Our focus in this work is on deriving a physics-based degradation model for electrolytic capacitors under thermal stress conditions. As part of our methodology, we study the effects of accelerated aging due to thermal stress on a batch of capacitors stored at high ambient temperature conditions. This provides a framework for supplementing theoretical modeling with data collected from simultaneous experiments, which is then used to validate the derived models. This work represents a first step toward combining data driven and physics-based approaches for modeling capacitor degradation. The case study shows how the proposed technique is applied to a batch of identically manufactured capacitors.

LTCC multilayer substrate (LTCC, Low Temperature Co-fired Ceramic) is one of the most widely used substrate in the high performance MCM (MCM, multi-chip module). Many kinds of passive elements and active devices can be integrated on the surface of the substrate. As one kind of the passive element, solid tantalum electrolytic capacitor has many advantages such as the bigger capacity per unit volume and the lower resistivity impedance, which are benefit for the emission performance of the MCM modules. In this paper, two kinds of process are used for the assembly of large-scale solid tantalum electrolytic capacitor surface mounted on the LTCC multilayer substrate. Verified experiments are carried out on the basis of soldering and experimental process analysis. A new soldering method is creatively proposed to solve the reliable problem of the soldering of solid tantalum electrolytic capacitors on the LTCC substrate. After environment tests, the resistance between tantalum capacitor lead and soldering pad is less than 100 milliohm, the shear strength of tantalum capacitor joint is larger than 50N. And this method is successfully applied in the existing products.

The capacitor is a passive electrical device, used to collect electrical energy by generating a potential difference. It is generally consisting of combination of two conductors placed next to each other separated by dielectric medium. The performance of a capacitor expressed in terms of the capacitance (C) depends on the dimension/geometry of the plate/electrode and the dielectric constant of the material, where the dielectric can be defined by insulating medium having permittivity, with no AC power losses or DC leakage. The capacitor shows different response to AC and DC sources. These are mainly used to supply power in several electronic and electrical systems. Therefore, this chapter provides the fundamental aspects of the capacitors and their basic properties. It emphasizes on the parallel plate model, the basic terminologies associated with the capacitors along with the equivalent circuits of the capacitor and its response to the externally applied AC and DC sources. It also describes about different types of capacitors that are being fabricated using different materials and different construction techniques. These different types of capacitors provide some unique properties.

Printed circuit boards (PCBs) are an essential and central component of electronic waste. The rapid depletion of natural resources, massive generation of end-of-life PCBs and inherently metal-loaded values inevitably call for recycling and recovery. This review critically discusses the systematic and sequential processes adopted for PCB metallic recoveries via physical, pyrometallurgical, hydrometallurgical, and combined technologies. Pre-treatments play a decisive and significant role in upgradation and efficient metal extraction. A novel combination of different pre-treatments and hybrid thermal-chemical routes are often reported for improved separation efficiency and performance. Selective recovery (using solvent extraction, precipitation, polymer inclusion membrane, adsorption, ion exchange) of high purity product from multi-elemental leach solution has recently gained interest and is reviewed. Current recycling techniques at a commercial scale are preferably based on pyrometallurgy (smelting-refining), where electronic waste is only a fraction of the total feed stream. Electronic components such as monolithic ceramic capacitors, tantalum capacitors, integrated circuits, and central processing units mounted on the PCBs are important due to precious metals' presence. The futuristic recycling perspective should treat base and precious metal-rich components separately with minimal environmental effect, end product usage, and maximum economic benefit. Sustainable processing routes for converting discarded PCBs into value-added products should also be attempted, as amplified in this review. An integrated, definite framework for full resource recovery from waste PCBs was proposed.

Electronic products are ever growing in popularity, and tantalum capacitors are heavily used in small electronic products. Spent epoxy-coated solid electrolyte tantalum capacitors, containing about 22 wt.% of tantalum and 8 wt.% of manganese, were treated with selective leaching by hydrochloric acid and chlorination after removing the epoxy resin, and the products converted, respectively, to Mn(OH)2 and TaCl5. The effects of acid type, acid concentration, liquid–solid ratio, and reaction time were investigated to dissolve the manganese. The optimal selective leaching conditions were determined as 3 mol/L of HCl, 40 mL/g at 25 °C for 32 min. Next, residues of selective leaching after washing and drying were heated with ferrous chloride to convert to pure TaCl5. Mixing 48 wt.% of chloride and 52 wt.% of residues for a total of 5 g was conducted to complete the chlorination process in the tube furnace at 450 °C for 3 h. A total of 2.35 g of Ta was collected and the recovery of Ta achieved 94%. Finally, Mn(OH)2 and TaCl5 were separated and purified as the products.

This paper focuses on the development of new 150°C capable surface mount polymer tantalum capacitors and the enabling technologies. The conductivity stability of the conducting polymers at high temperatures as well as the equivalent series resistance (ESR) stability of the polymer tantalum capacitors at these temperatures were investigated in this study. Analysis of the oxygen permeation paths causing polymer oxidation and materials solutions for preventing oxygen permeation and polymer oxidation are described. The development of new cathode and protective coating material technology is presented. Their effectiveness in providing high temperature ESR stability is demonstrated by high temperature life test at 150°C of polymer capacitors.

Due to the importance of capacitance temperature stability in precise analog circuit applications, capacitance instability at elevated temperature of 125°C was investigated in tantalum capacitors with PEDOT:PSS counter electrodes. Capacitance-voltage measurement supposed that residual ions in the PEDOT:PSS dispersion caused an accumulation of charges at the dielectric-cathode interface which contributed to an increase in the dielectric constant and resulted in the capacitance increasing at high temperature. Based on the hypothesis, water wash process was applied and capacitance dropped significantly at high temperature. This study shows that an additional water wash process is necessary to improve the capacitance temperature stability after each dispersion dip step.

High-density passive components are needed for continued miniaturization of complex high-performance electronic systems. Tantalum (Ta) capacitors provide some of the highest volumetric densities achieved due to their combination of high-surface area and relatively high dielectric constant, but suffer from low frequency stability and large form-factors due to the electrode design. In this paper, a printed thin-film tantalum capacitor design is presented. Tantalum capacitor arrays of 1 μF/mm2 up to and beyond 1 MHz. The improved frequency stability comes from the ultra-thin structure of the capacitors, which reduces the path length of the charging and discharging current. The capacitors showed low equivalent series resistance and consistent electrical performance before and after thermal moisture testing at 65°C and 95% relative humidity for 500 h and 1000 h. Due to the ultra-low form-factor, the thin-film Ta capacitor technology can be extended to highly-miniaturized power converters with efficient substrate- or wafer-scale integration.

Recycling rare metal tantalum from waste tantalum capacitors (WTCs) is significant to alleviate the shortage of tantalum resource. However, environmental problems will be caused if the organic materials from WTCs are improperly disposed. This study presented a promising vacuum pyrolysis technology to recycle the organic materials from WTCs. The organics removal rate could reach 94.32 wt% according to TG results. The optimal parameters were determined as 425 °C, 50 Pa and 30 min on the basis of response surface methodology (RSM). The oil yield and residual rate was 18.09 wt% and 74.94 wt%, respectively. All pyrolysis products can be recycled through a reasonable route. Besides, to deeply understand the pyrolysis process, the pyrolysis mechanism was also proposed based on the product and free radical theory. This paper provides an efficient process for recycling the organic material from WTCs, which can facilitate the following tantalum recovery.

The treatment of end-of-Life products is one of the key steps for progression towards a circular economy. In this context, mobile phone recycling has attracted considerable attention in recent years due to the high metal concentrations in printed circuit assemblies (PCAs). Contrary to precious metals, the recycling technologies for tantalum and rare earths are less well established despite their high importance for future sustainable technologies. In this study, mobile phone samples were manually dismantled into their main constituents and the qualitative distribution of elements in the PCA was determined. Tantalum capacitors can be visually distinguished from other components, whereas neodymium was detected in easily separable non-magnetic components sized between 0.5 and 1.5 mm. From tantalum capacitors, a tantalum rich-powder with a grade of 50% was obtained via a leaching process followed by an oxidizing heat treatment, while neodymium-rich fractions (4 to 14%) were obtained by sieving, magnetic and density separations., SCOPUS: cp.p, info:eu-repo/semantics/published

Increasingly dense microprocessors will require high-density passive components that can enable integrated power delivery with larger conversion ratios and higher output currents. Of these, nanoparticle-based tantalum capacitors can provide some of the highest volumetric densities compared to other capacitor technologies, due to the high surface area-to-volume ratio. Additionally, their temperature-stable dielectric can handle higher current ratings. However, the complex nanoparticle-based electrode structure results in long conduction paths, resulting in higher ESR and reduced frequency stability. A model is needed that can accurately predict the relationship between capacitor nanostructure and electrical performance so that the nanostructure can be optimized to meet the theoretical limits of device performance. This paper develops such a model, and demonstrates its accuracy by characterizing a real tantalum capacitor device. The model is then used to study the effect of capacitor materials and device geometry on the device performance, including capacitance density, frequency stability, and ESR.

Waste printed circuit boards (WPCBs) are valuable urban ore for recycling. Many efforts have been done to recover resources from basal boards of WPCB. In addition to basal boards, WPCBs contain many electronic components. However, the recycling technology for electronic components has been poorly developed. This study proposed an integrated and environment-friendly technology for recycling waste tantalum capacitors (WTCs) of WPCBs. Firstly, the WTCs were treated by argon pyrolysis to decompose mold resin. The pyrolysis temperature of 550 °C and holding time for 30 min were considered as the optimal parameters. Then, the pyrolysis residues were performed by crush and magnetic separation to recover nickel-iron terminals. Finally, chloride metallurgy (CM) was used to recover rare metal tantalum (Ta). The Ta recovery rate could reach 92.87 ± 0.36%. The optimal parameters were determined as temperature of 493 °C, adding FeCl 2 ·4H 2 O of 53 wt% and holding time for 150 min based on the response surface methodology (RSM). This study exploits an efficient approach for recycling WTCs and provides a reference for future industrial application.