Search Results (29)

The rapid growth in electronic waste (e-waste) generation highlights the urgent need for efficient and environmentally sustainable methods for metal recovery. This study focuses on the selective recovery of valuable metals from multilayer ceramic capacitors (MLCCs), commonly found in printed circuit boards (PCBs) of post-consumer electronics. MLCCs were manually recovered from dismantled computer PCBs, thermally treated, pulverized, and characterized using X-ray fluorescence and X-ray diffraction techniques. To evaluate green alternatives to traditional acid leaching, three deep eutectic solvents (DESs) based on choline chloride (ChCl) were prepared: citric acid (CA), glycerol (GLY), and a ternary (GLY-CA) mixture of both (GLY-CA). Leaching experiments were conducted over a 24 h period and analyzed using atomic absorption spectroscopy. The results showed complete recovery (100%) of copper using both CA and the GLY-CA mixture, while nickel recovery reached 100% with CA and moderate levels with GLY-CA. Zinc recovery was also high (99%) with both CA and GLY-CA. Iron showed a maximum recovery of 60%, potentially due to its occurrence in various chemical forms. The ternary DES (GLY-CA) demonstrated lower viscosity, improving handling and operational efficiency. These findings highlight the potential of citric-acid-based and ternary (GLY-CA) DESs as effective, low-toxicity leaching agents for the recovery of critical metals from MLCCs. Full article

Cognitive impairments, particularly in the context of neurodegenerative diseases, are associated with disruptions in mitochondrial function and key metabolic pathways. This study investigates the impact of short-term scopolamine exposure on mitochondrial DNA (mtDNA) stability and the kynurenine pathway (KP) in the hippocampus, a brain region central to learning and memory. We analyzed the mitochondrial D-loop region for mutations and heteroplasmy levels in hippocampal tissue from rats exposed to scopolamine (1 mg/kg/0.4 mL/cc i.p. x 14 days). Additionally, the expression of the KP enzymes kynurenine aminotransferase (KAT I, KAT II) and kynurenine 3-monooxygenase (KMO) and receptors aryl hydrocarbon receptor (Ahr) and G protein-coupled receptor 35 (GPR35) was evaluated using quantitative PCR. Neither significant mutation nor heteroplasmy changes were observed in the mtDNA D-loop region between the scopolamine-treated and control groups. Similarly, the hippocampal expression levels of the kat I, kat II, kmo and ahr and gpr35 genes remained unchanged, indicating no activation of this metabolic pathway under short-term scopolamine exposure. These findings suggest that the mitochondrial genome in the hippocampus remains stable under acute pharmacological stress induced by scopolamine, with no significant activation of the KP. These results underline the distinction between transient, reversible cognitive deficits and chronic neurodegenerative processes, providing insights for therapeutic approaches targeting specific stages of cognitive change. Full article

The high-temperature sintering characteristics of PLZT not only lead to lead volatilization and component mismatch but also limit its compatibility with low-cost electrode materials (such as Cu), making it a key bottleneck in its industrialization. In this study, PLZT dielectric ceramics were prepared using a glass-free densification process. Additionally, rare earth element Nd³⁺ was used for A-site doping to regulate the phase composition and domain structure of the material, and the relaxation characteristics and energy storage performance of PLZT were investigated. The results show that Nd³⁺ doping shifts the Raman 144 cm⁻¹ peak redward by 2.7 cm⁻¹. The P-E loop exhibits a narrow double-loop characteristic, with residual polarization reduced to 0.7 μC/cm² and maximum polarization reaching 17.7 μC/cm². When x = 0.07, a high energy storage density (W_rec = 3.98 J/cm³ and efficiency (η = 85%, x = 0.05) were achieved at 500 kV/cm. Through charge–discharge testing, the power density was determined to be 172.23 MW/cm³, with a discharge time τ_0.9 = 9.17 ns. This work could facilitate its application in multilayer ceramic capacitors (MLCCs) and embedded energy storage devices. Full article

Fiber-optic Fabry–Pérot (F–P) sensors offer significant potential for non-invasive hemodynamic monitoring, but existing sensing systems face limitations in multi-channel measurement capabilities and dynamic demodulation accuracy. This study introduces a sparse-frequency-scanning white-light interferometry (SFS-WLI) system with an adaptive mode-locked cross-correlation (MLCC) algorithm to address these challenges. The system leverages telecom-grade semiconductor lasers (191.2–196.15 THz sweep range, 50 GHz step) and a Fibonacci-optimized MLCC algorithm to achieve real-time cavity length demodulation at 5 kHz. Compared to normal MLCC algorithm, the Fibonacci-optimized algorithm reduces the number of computational iterations by 57 times while maintaining sub-nanometer resolution under dynamic perturbations. Experimental validation demonstrated a carotid–radial pulse wave velocity of 5.12 m/s in a healthy male volunteer. This work provides a scalable and cost-effective solution for cardiovascular monitoring with potential applications in point-of-care testing (POCT) and telemedicine. Full article

A full characterization of multilayer ceramic capacitors including variations in capacitance, series resistance, and series inductance is accomplished by measuring their RF response while being submitted to mechanical stress. This allows for the first time quantifying the degradation of the device’s RF performance when cracks form within its structure. In this regard, the main challenge is designing an interface for measuring the high-frequency response of a capacitor using a vector network analyzer as a bending test on a PCB in progress, which is achieved here by using a microstrip-based test fixture. The results indicate that there is an overestimation of its response to microwave stimuli when considering only the degradation impact as a reduction in capacitance. Capacitors of representative sizes and capacitances are analyzed to show the usefulness of the proposal, whereas the validity of the results is verified by observing the correlation with measurements collected using microprobes and performing optical inspections of cross-sectioned samples. Full article

A rework of electronic assemblies and the reuse of electronic components are the most effective ways to reduce electronic waste. Since neither components nor substrates were developed with the intention of multiple usage, the question of how the integrity of lead-free solder joints is affected by multiple reflow operations is crucial for the implementation of any reuse strategy. Therefore, various types of 1206 multilayer ceramic capacitors (MLCCs) differing in their capacitance value and dielectric type (X5R, X7R, Y5V, NP0) were soldered on test printed circuit boards (PCBs) having a pure Cu-metallization surface in order to investigate the intermetallic reactions during multiple reflows. The metallization system on the MLCC-component side consisted of a thick film of Ni covered by galvanic-deposited Sn. The reflow experiments were conducted using a hypoeutectic SnAgCu solder. The results show the formation of a Cu₆Sn₅ intermetallic phase on both metallizations, which grows homogeneously with the number of reflows. Moreover, an ongoing decomposition of the solder into Ag-enriched and depleted zones was observed. The effect of these microstructural changes on the functionality of the solder joint was investigated by mechanical shear experiments and electrical four-point capacitance measurements. Full article

In the last decade, a higher level of reliability has become a compulsory demand when it comes to modern DC-DC converters. This work addresses the main reliability metrics: in many studies, the failure rate λ and MTBF of an output capacitor bank used within a high-current low-voltage buck converter have shown that the output capacitor bank is the most critical component within the converter. Many authors dealt with this issue by performing reliability predictions. The majority of studies use only one specific standard prediction to solve the problem. Herein, the calculation was performed using both the older standard, MIL-HDBK-217, and the latest one, Telcordia SR-332, providing a benchmark comparison between the two, which is a helpful tool for output capacitor selection in early-stage design. The military standard was well accepted for decades in reliability prediction, even in industrial electronics, and is still used today in a critical manner because there have been no more updates after the latest version, MIL-HDBK-217F—Notice 2, was released in 1995. Since then, newer prediction standards have appeared in the electronics reliability market. Over time, this standard was mostly used, but it does not accurately model the reliability because of a lack of taking account of the mission profile. The above-mentioned newer standard—i.e., Telcordia SR-332—also tries to compensate for the lack of the newest component technology in the older standard (which is the first standard released on the market), supplying useful design data for design engineers who use the so-called “design with reliability in mind” concept. This provides the designer of DC-DC converters with a comparison between the reliability values when the two mentioned standards are used. This paper establishes the environmental condition for the passive components by means of a point of load (PoL) buck converter that is used for both calculation methods. The influence of temperature and several specific concepts, like reference conditions, operating conditions, ripple, and internal self-heating, were taken into account in order to display the results. The temperature for the capacitor’s capsule needed in π_T stress factor calculation was derived using PSPICE simulation. High-fidelity and dedicated SPICE models provided by the manufacturer were used for MOSFETs, polymer electrolytic, and MLCC capacitors that comprise the converter. Full article

In this study, a current-equalization technology utilizing a variable-capacitance technique for a multiphase inductor–inductor–capacitor (LLC) converter is studied. Accordingly, the proposed method involves adjusting the resonant capacitance of the LLC resonant converter to balance the currents between phases. This is achieved primarily by biasing ferroelectric multilayer ceramic capacitors (MLCCs) through a step-down circuit and a common-mode bias structure. These ferroelectric MLCCs serve as the resonant elements, allowing for variable capacitance by leveraging capacitance sensitivity to their trans voltages. This approach provides additional control flexibility to the resonant circuit. Furthermore, since each phase operates independently, the circuit can be scaled to accommodate any number of phases. Moreover, all switches in the circuit have zero-voltage switching (ZVS) turn-on, minimizing switching losses. This study initially analyzes and evaluates the proposed common-mode bias variable capacitance technique and the corresponding operational principles. Subsequently, a two-phase LLC experimental circuit based on a field-programmable gate array (FPGA) digital controller is utilized to assess current equalization and efficiency. That is to say, this experimentation aims to validate the effectiveness of the current-equalization variable-capacitance technique in an LLC resonant converter. Full article

Multilayer ceramic capacitors (MLCCs) are critical components when thermal processes such as reflow desoldering are used during rework of electronic assemblies. The capacitor’s ferroelectric BaTiO₃ body is very brittle. Therefore, thermomechanical stresses can cause crack formation and create conductive paths that may short the capacitor. In order to assess the thermally induced mechanical stresses onto an MLCC during reflow desoldering, simulations were carried out, which make use of a framework of computational fluid dynamics and thermomechanical models within the ANSYS software package. In the first step, CFD simulations were conducted to calculate the transient temperature field in the surrounding of the MLCC component, which was then used as an input for FEM simulations to compute the arising mechanical stresses inside the MLCC. The results of the simulations show that the major contribution to mechanical stresses within the MLCC component comes from the mismatch in thermal expansion between the printed circuit board and the MLCC. The temperature gradients along the MLCC component are rather small and account only for moderate internal stresses within the brittle BaTiO₃ body. Full article

Multilayer ceramic capacitors (MLCCs) prepared using Ba_1−xSr_xTiO₃ (BST) ceramics exhibit high dielectric constants (~1000), low dielectric loss (<0.01), and high breakdown voltage, with particularly significant tunability in dielectric properties (>50%) and with poor temperature stability. Doping-dominated temperature stability improvements often result in unintended loss of dielectric properties. A non-doping method has been proposed to enhance the temperature stability of BST capacitors. The composite gradient multilayer (CGML) ceramic capacitors with Ba_xSr_1−xTiO₃, where 0.5 < x < 0.8, as the dielectric, were prepared using a tape-casting method and sintered at 1250 °C. There exists a dense microstructure and continuous interface between the Ba_xSr_1−xTiO₃ thick film and the Pt electrodes. CGML ceramic capacitors feature a high dielectric constant at 1270, a low dielectric loss of less than 0.007, and excellent frequency and temperature stability. The capacitor showcases remarkable dielectric properties with a substantial tunability of 68% at 100 kV/cm, along with a notably consistent tunability ranging from 20% to 28% at 15 kV/cm across temperatures spanning from 30 to 100 °C, outperforming single-component BST-MLCCs in dielectric performance. Full article

A large amount of multi-layer ceramic capacitor (MLCC) is mounted inside a printed circuit board (PCB) constituting electronic components. The use of MLCC in electric vehicles and the latest mobile phones is rapidly increasing with the latest technology. Environments in which electronic components are used are becoming more diverse and conformal coatings are being applied to protect mounted components from these environments. In particular, MLCCs in electronic components mainly have voltage applied. They might be used in environments where humidity exists for various reasons. In a humid environment, electrochemical migration (ECM) will occur, with the cathode and anode on the surface of the MLCC encountering each other. This can result in product damage due to a short circuit. In this study, the effects of voltage, NaCl concentration, and distance between electrodes on a non-mount MLCC, surface mount MLCC, and solder pad pattern were evaluated using a water drop test (WDT). Based on the analysis of the effects of the presence of conformal coating, applied voltage, concentration of NaCl, and the distance between electrodes, a mechanism model for ECM behavior in MLCCs was proposed. Full article

The need to reduce energy consumption in buildings, the emergence of light-emitting diode (LED) lamps in lighting around 2010, their long lifetime, and the 2025 target to use only LED lamps are changing the existing composition of Category 3 waste electrical–electronic equipment (WEEE) and creating expectations for simple, high-concentration recycling streams. In this study, multi-layer ceramic capacitors (MLCCs) detached from the lighting sector’s WEEE were characterised for the presence of rare earth elements (REEs) and precious metals (PMs). Their digestion was carried out with HNO₃ and aqua regia on a heating plate and characterised using inductively coupled plasma optical emission spectroscopy (ICP-OES) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The contents of REEs and PMs found in the MLCCs were 0.84 wt% and 0.60 wt%, respectively, and create an economic stored value that is essentially defined by PMs of 98.67% and by palladium (Pd) of 78.37%. The analysis showed that the content of the main elements was: neodymium (Nd) 0.366 wt%, yttrium (Y) 0.220 wt%, dysprosium (Dy) 0.131 wt%, silver (Ag) 0.467 wt%, and Pd 0.105 wt%. These results indicate the need for selective removal and separate recycling processes of MLCCs from WEEE drivers. Full article

The overseas market expansion strategy is important for achieving competitive advantage and sustainable growth of global electronic component companies. Although the global electronic component market has grown rapidly recently, research focusing on the innovation strategy of global electronic component companies’ expansion into overseas markets is scarce. This paper defines the key factors that influence the success of a global electronic component company’s overseas market expansion strategy based on the Technology, Organization, and Environment (TOE) framework and quantitatively identifies the relative importance of factors at the technology, organization, and environmental levels through Analytic Hierarchy Process (AHP) analysis. As a case study, we analyze Samsung Electro-Mechanics, which has grown as a global electronic components company through an overseas market expansion strategy in recent decades. As a result of the analysis, among the three top factors defined as key factors, the technology factor was evaluated as the most important factor, and among the subfactors of the technology factor, “R&D Availability”, and “Production Availability” were analyzed as the most important influencing factors. These analysis results suggest that global electronic component companies can achieve successful results when they pursue overseas market expansion strategies by prioritizing technology development and focusing on growth strategies suited to the market environment. This study is meaningful as an academic study focusing on the overseas market expansion strategies of global electronic component companies and makes a practical contribution by providing management implications that can be taken by electronic component companies seeking to expand overseas markets. Full article

To fabricate multilayer ceramic capacitors (MLCCs) that can withstand external impacts, technologies to achieve excellent adhesion and mechanical strength of the cover layer should be essentially developed. Low adhesion and strength of the cover layer can lead to delamination and cracks in the MLCC, respectively. In this study, we present a method for applying polydopamine (PDA), a mussel-inspired adhesive protein, for as robust cover layer on an MLCC. Barium titanate (BT) particles treated with PDA increase the dispersion stability of the BT/PDA slurry, preventing re-agglomeration of the particles and enhancing the adhesiveness and strength owing to the cohesive properties of PDA. Compared to the BT layer, the adhesion of the BT/PDA layer was significantly enhanced by 217%; consequently, the compression modulus of the BT/PDA cover layer increased by 29.4%. After firing, the N-doped graphitic PDA played an important role in producing an MLCC cover layer with increased hardness and toughness. Furthermore, the N-doped graphitic PDA with a hydrophobic surface forms tortuous moisture paths in the cover layer, preventing the degradation of insulation resistance of the MLCC. Full article

In this paper, Li_xCa_(1−x)Cu₃Ti₄O₁₂ (LCCTO) solid solutions were successfully synthesized. XRD diagrams showed that dopant acceptor Li⁺ cations, in a concentration range of x = 0.01–0.10, were successfully merged into CCTO structure. It was found that doping with low concentrations of lithium (x < 0.05) inhibited grain growth during annealing; however, for x > 0.05, the grain growth process resumed. Permittivity and dielectric losses of obtained LCCTO ceramics were analyzed by the means of impedance spectroscopy in a frequency range from 10⁻¹ to 10⁶ Hz. It was revealed that acceptor doping with lithium at an appropriate concentration of x = 0.05 allowed to obtain ceramics with a permittivity level of ε′ = 3 × 10⁴ and low dielectric losses tanδ < 0.1 at 1 kHz. Further addition of lithium in a concentration range of x = 0.075–0.10 led to a sharp decline in permittivity and an increase in dielectric losses. It was discovered that lithium addition to CCTO ceramics drastically decreased grain boundary resistivity from 115 MΩ·cm to 5–40 MΩ·cm at x = 0.01–0.10. Using Havriliak–Negami equation, the relaxation times for grain dipoles and grain boundary dipoles were found to be ranging from 0.8 × 10⁻⁶ to 1.7 × 10⁻⁶ s and from 0.4 × 10⁻⁴ to 7.1 × 10⁻⁴ s, respectively. The developed materials can be used in the manufacture of Multilayer Ceramic Capacitors (MLCC) as a dielectric. Full article