Search Results (186)

This article aims to utilize a microelectromechanical system (MEMS) to modulate coupling behavior of silicon nitride (Si₃N₄) waveguides to perform an optical switch based on a directional coupling (DC) mechanism. There are two states of the switch. First state, a Si₃N₄ wire is initially positioned up suspended in the air. In the second state, this wire will be moved down to be placed between two arms of the DC waveguides, changing the coupling behavior to achieve bar and cross states of the optical switch function. In the future, the MEMS will be used to move this wire down. In this work, we present simulations of the two static states to optimize the DC structure parameters. Based on the simulated results, the device size is 8.8 μm × 55 μm. The insertion loss is calculated to be approximately 0.24 dB and 0.33 dB, the extinction ratio is approximately 24.70 dB and 25.46 dB, and the crosstalk is approximately −24.60 dB and −25.56 dB, respectively. In the C band of optical communication, the insertion loss ranges from 0.18 dB to 0.47 dB. As such, this device will exhibit excellent optical switch performance and provide advantages in many integrated optics-related optical systems applications. Furthermore, it can be used in optical communications, data centers, LiDAR, and so on, enhancing important reference value for such applications. Full article

To develop solutions to the frequency instability and failure of silicon micromechanical resonant accelerometers, the state characteristics of micromechanical resonant accelerometers are investigated under temperature and vibration stresses. Through theoretical analysis and finite element simulation, the following is found: the Young’s modulus of silicon varies with temperature, causing a resonance frequency shift of −1.364 Hz/°C; the residual stress of temperature change affects the resonance frequency shift of the microstructure, causing it to be 5.43 Hz/MPa (tensile stress) and −5.25 Hz/MPa (compressive stress); thermal expansion triggers the failure of the bonding wire, and, in the range of 10 °C to 150 °C, the peak stress of the electrode/lead bond area increases from 83.2/85.6 MPa to 1.08/1.28 GPa. The failure mode under vibration stress is resonance structure fracture and interlayer peeling. An isolation frame design is proposed for the sensitive part of the microstructure, which reduces the frequency effects by 34% (tensile stress) and 15% (compressive stress) under temperature-variable residual stresses and the maximum value of the structural root mean square stresses by 69.7% (X-direction), 63.6% (Y-direction), and 71.3% (Z-direction) under vibrational stresses. Full article

Silicon carbide (SiC) half-bridge power modules are widely utilized in new energy power generation, electric vehicles, and industrial power supplies. To address the research gap in collaborative validation between electro-thermal coupling models and process reliability, this paper proposes a closed-loop methodology of “design-simulation-process-validation”. This approach integrates in-depth electro-thermal simulation (LTspice XVII/COMSOL Multiphysics 6.3) with micro/nano-packaging processes (sintering/bonding). Firstly, a multifunctional double-pulse test board was designed for the dynamic characterization of SiC devices. LTspice simulations revealed the switching characteristics under an 800 V operating condition. Subsequently, a thermal simulation model was constructed in COMSOL to quantify the module junction temperature gradient (25 °C → 80 °C). Key process parameters affecting reliability were then quantified, including conductive adhesive sintering (S820-F680, 39.3 W/m·K), high-temperature baking at 175 °C, and aluminum wire bonding (15 mil wire diameter and 500 mW ultrasonic power/500 g bonding force). Finally, a double-pulse dynamic test platform was established to capture switching transient characteristics. Experimental results demonstrated the following: (1) The packaged module successfully passed the 800 V high-voltage validation. Measured drain current (4.62 A) exhibited an error of <0.65% compared to the simulated value (4.65 A). (2) The simulated junction temperature (80 °C) was significantly below the safety threshold (175 °C). (3) Microscopic examination using a Leica IVesta 3 microscope (55× magnification) confirmed the absence of voids at the sintering and bonding interfaces. (4) Frequency-dependent dynamic characterization revealed a 6 nH parasitic inductance via Ansys Q3D 2025 R1 simulation, with experimental validation at 8.3 nH through double-pulse testing. Thermal evaluations up to 200 kHz indicated 109 °C peak temperature (below 175 °C datasheet limit) and low switching losses. This work provides a critical process benchmark for the micro/nano-manufacturing of high-density SiC modules. Full article

In the process of machining an aluminum matrix silicon carbide (SiCp/Al) composite material using wire electric discharge machining (WEDM), the thermal conductivity and dielectric properties of working fluid, such as discharge medium and cool carrier, directly determine the material removal rate (MRR) and surface roughness (R_a). In this paper, graphene-working fluid is innovatively used as working medium to optimize the discharge process due to its high thermal conductivity and field emission characteristics. The single-factor experiments show that graphene can increase the MRR by 11.16% and decrease the R_a by 29.96% compared with traditional working fluids. In order to analyze the multi-parameter coupling effect, an L16 (4⁴) orthogonal test is further designed, and the effects of the pulse width (T_on), duty cycle (DC), power tube number (PT), and wire speed (WS) on the MRR and R_a are determined using a signal-to-noise analysis. Based on a gray relational grade analysis, a multi-objective optimization model was established, and the priority of the MRR and R_a was determined using an AHP, and finally the optimal parameter combination (T_on = 22 μs, DC = 1:4, PT = 3, WS = 2) was obtained. Full article

The surface quality of diamond wire sawing (DWS) wafers directly affects the efficiency and yield of subsequent processing steps. This paper investigates the motion trajectory of abrasives in ultrasonic-assisted diamond wire sawing (UADWS) and its mechanism for improving surface quality. The influence of ultrasonic vibration on the cutting arc length, cutting depth, and interference of multi-abrasive trajectories was analyzed through the establishment of an abrasive motion trajectory model. The ultrasonic vibration transforms the abrasive trajectory from linear to sinusoidal, thereby increasing the cutting arc length while reducing the cutting depth. A lower wire speed was found to be more conducive to exploiting the advantages of ultrasonic vibration. Furthermore, the intersecting interference of multi-abrasive trajectories contributes to enhanced surface quality. Experimental studies were conducted on monocrystalline silicon (mono-Si) to verify the effectiveness of ultrasonic vibration in improving surface morphology and reducing wire marks during the sawing process. The experimental results demonstrate that, compared with DWS, UADWS achieves a significantly lower surface roughness Ra and generates micro-pits. The ultrasonic vibration induces a micro-grinding effect on both peaks and valleys of wire marks, effectively reducing their peak–valley (PV) height. This study provides a theoretical basis for optimizing UADWS process parameters and holds significant implications for improving surface quality in mono-Si wafer slicing. Full article

Triboelectric nanogenerators have attracted extensive attention as they can complete sensing during energy conversion, triggering a series of self-powered designs. Traditional TENG bipolar independent fabrication technology requires secondary motion control, which limits its application scenarios. In this work, we propose a flag-type TENG prepared using in situ electrospinning technology, in which the connecting region is obtained by electrospinning deposition of PVDF on nylon as the receiving electrode. The active area is isolated with silicone oil paper. After electrospinning, the silicone oil paper was removed, and the distance between the nylon and PVDF is far beyond the van der Waals range. Thus, contact separation can be effectively carried out under the action of wind. The device has been proven to be able to be used for monitoring wind conditions at high-speed rail stations and enables completely self-powered monitoring of the wind level using self-powered LED coding. The device no longer relies on additional batteries or wires to work, providing additional ideas for future self-powered system design. Full article

Understanding wire-cut electrical discharge machining (WEDM) parameters’ impact on surface roughness (Ra) is crucial for optimizing processes. This study uses artificial neural network (ANN) techniques to estimate the surface roughness of Al/SiC composites during WEDM, examining how process parameters affect the roughness. The experiment used a stir casting aluminum alloy with a 7.5% silicon carbide metal matrix composite (MMC), adjusting parameters like the wire tension (WT), servo voltage (SV), peak current (IP), pulse on time (TON), and pulse off time (TOFF). An ANN model was created to forecast the surface roughness. The study developed an ANN model to forecast surface roughness in Al/SiC composites during WEDM, demonstrating its accuracy in identifying the link between surface finish and input parameters, thereby improving the surface quality. The ANN model accurately predicted the surface roughness based on WEDM parameters, with strong correlations between predictions and actual data, demonstrating its ability to estimate surface quality accurately. Full article

Monocrystalline silicon is widely used in the semiconductor industry. During wafer machining with a diamond wire saw (DWS), a worn diamond wire can affect the slicing quality. To assess the effect of diamond wire wear on wafer machining, in this study, the impact of diamond wire wear on the wafer’s total thickness variation (TTV) and surface quality was examined at a wire velocity of 1.8 m/s and a feed rate of 0.5 mm/min. Through a single-factor experiment, the effects of the wire velocity, feed rate, and workpiece thickness on diamond wire wear were explored. The outcomes demonstrate that the wear rate was higher in the early and late wear periods, and the wafer machining quality was poor in these two periods. During the stable wear period, the machined wafer exhibited high quality, while the wear rate remained stable. Under the condition of machining the same area of the workpiece, with an increase in wire velocity, the wear quantity for the diamond wire was reduced. As the feed rate and workpiece thickness increased, the wear quantity of the diamond wire increased. The diamond wire wear remained roughly constant when the wire velocity and feed rate increased at the same ratio. Full article

This paper presents the design and characterisation of a novel double-sided cooling, wire-bondless half-bridge power module incorporating silver sintering technology and silicon carbide MOSFETs. Initially, the module was meticulously designed, optimised, and simulated using Ansys (Electronics Desktop 2021 R1) Q3D and Icepak to assess its stray parameters and thermal performance, respectively. The module has a low simulated stray inductance of 4.7 nH, which would be even lower in a multi-chip version of the design. Additionally, the thermal performance of the double-sided power module is compared with the single-sided version, showing a 30 °C reduction in junction temperature. Following the design work, a double-sided cooled half-bridge module was successfully fabricated, which underwent double pulse analysis and single-phase inductive load testing. Die attachment within the module employs nanosilver paste, with the flexibility to adjust the length of the copper connector to meet diverse requirements. The design exhibits remarkable compactness, and comprehensive electrical testing affirms its suitability for practical applications. Full article

Three-dimensional flexible solar fabrics based on hydrogenated amorphous silicon (a-Si:H) thin film solar cells were prepared and characterized. A glass fiber fabric with a polytetrafluoroethylene (PTFE) coating proved to be a suitable textile substrate. Interwoven metal wires enable an integrated electrical interconnection. An array of solar cells consisting of an a-Si:H layer stack with a highly p-type/intrinsic/highly n-type doping profile was deposited onto it. Silver was used as the back contact with indium tin oxide (ITO) as the front contact. The best solar cells show an efficiency of 3.9% with an open-circuit voltage of 876 mV and a short-circuit current density of 11.4 mA/cm². The high series resistance limits the fill factor to 39%. The potential of the textile solar cells is shown by the achieved pseudo fill factor of 79% when neglecting the series resistance, resulting in a pseudo efficiency of 7.6%. With four textile solar cells connected in a series, an open-circuit voltage of about 3 V is achieved. Full article

As semiconductor packaging technologies face limitations, through-silicon via (TSV) technology has emerged as a key solution to extending Moore’s law by achieving high-density, high-performance microelectronics. TSV technology enables enhanced wiring density, signal speed, and power efficiency, and offers significant advantages over traditional wire-bonding techniques. However, achieving fine-pitch and high-density interconnects remains a challenge. Solder flip-chip microbumps have demonstrated their potential to improve interconnect reliability and performance. However, the environmental impact of lead-based solders necessitates a shift to lead-free alternatives. This review highlights the transition from Sn-Pb solders to lead-free options, such as Sn-Ag, Sn-Cu, Sn-Ag-Cu, Sn-Zn, and Bi- or In-based alloys, driven by regulatory and environmental considerations. Although lead-free solders address environmental concerns, their higher melting points pose challenges such as thermal stress and chip warping, which affect device reliability. To overcome these challenges, the development of low-melting-point solder alloys has gained momentum. This study examines advancements in low-temperature solder technologies and evaluates their potential for enhancing device reliability by mitigating thermal stress and ensuring long-term stability. Full article

The most common aftereffect of severe burns in patients is hypertrophic scarring. Hypertrophic scars typically form following severe burns; it refers to excessive collagen production in the dermal layer during the healing process, resulting in an abnormal raised scar. Currently, practical treatments for suppressing hypertrophic scars include laser therapy, pressure therapy, and the application of silicone sheets for moisture retention. The most extensively used treatment involves compression therapy using specially designed garments for the affected areas. However, this method has limitations when applied to curved surfaces like the face. To address this issue, three-dimensional (3D) scanning and 3D printing techniques have been actively developed for face masks and have shown promising clinical results. Unfortunately, current facial masks under development lack a sensor system to measure pressure, making it difficult to ensure consistent and appropriate pressures during clinical trials. In this study, we have developed a burn pressure mask capable of real-time pressure monitoring. The facial mask developed in this study utilizes an FSR-type sensor to measure the pressure applied to the skin. We have also embedded electrical wires within the mask to enhance its comfort and wearability. For this study, two patients wore the facial mask with real-time pressure measurement capabilities for 4 weeks in 12 h per day on average. We evaluated whether the mask maintained the appropriate pressure range (15–25 mmHg) throughout the clinical trial and whether it effectively inhibited scar formation. Through the analysis of recorded pressure signal data, we confirmed that the patients consistently maintained the appropriate pressure while wearing the mask during the clinical trial. Additionally, we observed significant differences in skin moisture levels, transepidermal water loss, and scar thickness before and after the experiment. These findings suggest that the facial mask, featuring real-time monitoring capabilities, effectively prevents the formation of hypertrophic scars. Full article

Gate-oxide degradation in silicon carbide (SiC) metal oxide–semiconductor field-effect transistors (MOSFETs) is a significant concern. Consequently, several methods have been developed to monitor the aging degree. In this article, a temperature-independent method for gate-oxide degradation monitoring is proposed by measuring the minimum turn-off circuit parasitic inductor voltage v_{cir_min} at a specific gate resistor and voltage. The temperature sensitivity of v_{cir_min} is analyzed based on a derived model. Adjustment of the turn-off gate voltage and resistance is proposed to mitigate the impact of temperature on v_{cir_min}. The devices under test are aged by high-temperature gate bias (HTGB) experiments and are tested in double-pulse tests (DPT). A 32 V bias for 42 h and 25–150 °C temperature results in changes of 6.55% and 0.103% in v_{cir_min}, respectively. The experimental results show that the proposed method is effective in maintaining temperature independence. Additionally, the effects of bus voltage, load current, and bond wire failure on v_{cir_min} are also tested and analyzed. The proposed method provides a valuable tool for accurately monitoring SiC MOSFET gate-oxide degradation in scenarios characterized by significant temperature fluctuations. Full article

Diamond-wire sawing silicon waste (DSSW) derived from the silicon wafer sawing process may lead to resource waste and environmental issues if not properly utilized. This paper propounds a simple technique aimed at enhancing the efficiency of hydrogen production from DSSW. The hydrolysis reaction is found to become faster when DSSW is ground. Among the studied grinding agents, KCl has the best performance. The grinding duration and addition amount remarkably affect the final hydrogen yield and initial hydrogen generation rate (IHGR). Among all studied samples, DSSW-KCl 25 wt% ground for 3 min shows the best performance with a hydrogen yield of 86.1% and an IHGR of 399.37 mL min⁻¹ (g DSSW)⁻¹ within 650 s. The initial temperature is also found to have a significant influence on the hydrolysis of the DSSW-KCl mixture, and the reaction can proceed to 85% conversion in 100 s with an IHGR of 1383.6 mL min⁻¹ (g DSSW)⁻¹ at 338 K. The apparent activation energy for the hydrolysis reaction of the DSSW-KCl composite powder was found to be 45.62 kJ mol⁻¹ by means of an Arrhenius plot. The rate-determining step for the rapid reaction of DSSW to produce hydrogen is chemical reaction control, while the slow reaction is controlled by diffusion. Full article

Diamond wire saw silicon slurry (DWSSS) is a waste resource produced during the process of solar-grade silicon wafer preparation with diamond wire sawing. The DWSSS contains 6N grade high-purity silicon and offers a promising resource for high-purity silicon recycling. The current process for silicon extraction recovery from DWSSS presents the disadvantages of lower recovery and secondary pollution. This study focuses on the original DWSSS as the target and proposes flotation for efficiently extracting silicon. The experimental results indicate that the maximal recovery of silicon reached 98.2% under the condition of a dodecylamine (DDA) dosage of 0.6 g·L⁻¹ and natural pH conditions within 24 min, and the flotation conforms to the first-order rate model. Moreover, the mechanism of the interface behavior between DWSSS and DDA revealed that DDA is adsorbed on the surface of silicon though adsorption, and the floatability of silicon is improved. The DFT calculation indicates that DDA can be spontaneously adsorbed with the silicon. The present study demonstrates that flotation is an efficient method for extracting silicon from DWSSS and provides an available option for silicon recovery. Full article