Material–Structure–Function Integrated Additive Manufacturing of Degradable Metallic Bone Implants for Load-Bearing Applications

The integration of bio-adaptable performance, elaborate structure, and biological functionality for degradable bone implants is crucial in harnessing the body's regenerative potential to remold load-bearing bone defects. Herein, material–structure–function integrated additive manufacturing (MSFI-AM) is deployed to innovate novel zinc-based bone implants, namely Zn–Mg–Cu alloy. In situ alloying of AM and boundary engineering strategy yield prominent mechanical properties, and the degradation products enable a mechanical self-strengthened effect, thus coordinating mechanical degeneration and promoting mechanical adaptability. In addition, MSFI-oriented Zn alloy implants successfully manifest in situ multifunctions of augmenting osteogenesis, immunoregulation, angiogenesis, and anti-infective activity in vitro and expediting bone ingrowth and regeneration in vivo through the sustained release of divalent metal cations and triply periodic minimal surface (TPMS) structure construction. Overall, MSFI-AMed Zn alloy implants signify promising clinical translation prospects for load-bearing applications, and an integrated approach is proposed to endow degradable bone implants with boosted bio-adaptable performance and in situ bio-multifunctions.     

Effect of Prebonding Anneal on the Microstructure Evolution and Cu–Cu Diffusion Bonding Quality for Three-Dimensional Integration

Electroplated copper (Cu) films are often annealed during back-end processes to stabilize grain growth in order to improve their electrical properties. The effect of prebonding anneal and hence the effective initial grain size of the Cu films on the final bond quality are studied using a 300-nm-thick Cu film that was deposited on a 200-mm silicon (Si) wafer and bonded at 300°C. As compared with the control wafer pair with a prebonding anneal at 300°C for 1?h in N₂, the wafer pair without a prebonding anneal showed greater improvement in void density based on c-mode scanning acoustic microscopy (c-SAM). Dicing yield and shear strength were also enhanced when a prebonding anneal was not applied. This improvement is due to substantial grain growth of smaller Cu grains during the bonding process, which leads to a stronger Cu?CCu bond. Our work has identified a Cu?CCu bonding process with a lower total thermal budget, which is seen as a favorable option for future three-dimensional (3D) integrated circuit (IC) technology.     

Design of the Test System for the Dynamic Function of the SLC PCB

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Synthesis and characterisation of curcumin–M (M = B,Fe and Cu) films grown on p-Si substrate for dielectric applications

Metal-coordinated yellow curcumin was extracted from green natural sources and sublimated in vacuum to prepare thin films on p-Si and glass substrates for dielectric and optical investigations. The synthesised curcumin complexed with the metals boron, iron, and copper powders were crystalline while the prepared films were amorphous. The optical absorption spectrum of the prepared films showed similar two absorption band structure in the visible range. The onset energy of the main optical absorption band of the film was determined using the Tauc technique. The dielectric properties of this material were systematically studied for future applications in metal–insulator–semiconductor MIS field of applications. The complex dielectric properties were studied in the frequency range of 1–1000 kHz and was analysed. The important find is a large optoelectronic sensitivity so that the integral optical responsivity (S¹) reaches ∼1.0 A/W and the electrical conductivity increases under light illumination by ∼400–1000%. Generally, Curcumin metal complex can be used in small-k environmentally friendly production of microelectronic and optoelectronic devices.     

Evaluation of the corrosion performance of Cu–Al intermetallic compounds and the effect of Pd addition

Copper wire has become a mainstream bonding material in fine-pitch applications due to the rising cost of gold wire. In recent years, palladium-coated copper (Pd–Cu) wire is being increasingly used to overcome some constraints posed by pure Cu wire. During wire bonding with aluminum bond pads, different intermetallic compound (IMC) phases that have been identified at the bond interface are typically CuAl₂, CuAl and Cu₉Al₄. However, the corrosion susceptibility of these IMCs has not been investigated. This paper compares the electrical impedance and corrosion performance of the three types of Cu–Al IMCs in an acidic chloride medium by employing electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The analysis of the potentiodynamic polarization results was performed using Tafel extrapolation. A comparison was made with pure Cu and Al. The effect of Pd alloy on the IMC corrosion performance has also been studied. Among the three Cu–Al IMCs, Cu₉Al₄ was observed to have the largest corrosion rate followed by CuAl₂ and CuAl. For the metals, Cu was observed to have the lowest corrosion rate and Al is the most easily corroded. The addition of Pd of up to 10 wt.% replacement of the Cu in the alloys slightly improves the corrosion resistance of the metals and IMCs.     

Stress–Strain Characteristics of Tin-Based Solder Alloys for Drop-Impact Modeling

The stress–strain properties of eutectic Sn-Pb and lead-free solders at strain rates between 0.1 s⁻¹ and 300 s⁻¹ are required to support finite-element modeling of the solder joints during board-level mechanical shock and product-level drop-impact testing. However, there is very limited data in this range because this is beyond the limit of conventional mechanical testing and below the limit of the split Hopkinson pressure bar test method. In this paper, a specialized drop-weight test was developed and, together with a conventional mechanical tester, the true stress–strain properties of four solder alloys (63Sn-37Pb, Sn-1.0Ag-0.1Cu, Sn-3.5Ag, and Sn-3.0Ag-0.5Cu) were generated for strain rates in the range from 0.005 s⁻¹ to 300 s⁻¹. The sensitivity of the solders was found to be independent of strain level but to increase with increased strain rate. The Sn-3.5Ag and the Sn-3.0Ag-0.5Cu solders exhibited not only higher flow stress at relatively low strain rate but, compared to Sn-37Pb, both also exhibited higher rate sensitivity that contributes to the weakness of these two lead-free solder joints when subjected to drop impact loading.     

Design and Optimization of Quasi–Optical Frequency Multipliers

This paper presents a full–wave algorithm for the design and the optimization of quasi–optical frequency multipliers and discusses its implementation in a specialized computer code, able to simulate as a whole the non–linear device, the planar antenna and the embedding layered structure. The electromagnetic analysis of the multiplier is performed under the simplifying approximation of an infinite array excited by a uniform plane wave incident from the broadside direction. The array parameters are deduced from a full–wave analysis, based on the Method of the Moments, while the solution of the non–linear circuit is found by the Harmonic Balance Method.     

Towards the Use of Cu–S Based Synthetic Minerals for Thermoelectric Applications

Semiconductors - Most of the energy produced is lost, mainly as waste heat. Thermoelectricity, which can directly convert heat into electricity, is seen with huge potential to recover part of such...     

Design and Simulation of the Thin Film Pulse Transformer

A new thin film pulse transformer for using in ISND and ADSL systems has been designed based on a domain wall pinning model, the parameters of nano-magnetic thin film such as permeability and coercivity can be calculated. The main properties of the thin film transformer including the size,parallel inductance, Q value and turn ratio have been simulated and optimized. Simulation results show that the thin film transformer can be fairly operated in a frequency range of O.OO l-2O MHz.     

Theoretical Modeling of the Thermoelectric Properties of Fe2Ti1 –xVxSn Heusler Alloys

Semiconductors - Theoretical calculations of the electron structure and Seebeck coefficient in Fe2Ti1 –xVxSn alloys for the cases of a fully ordered L21 and partially disordered B2 Heusler...     

An Algorithm for the Design of a Cost-Optimized Topology for the Fixed Part of a GSM Network

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On the Design of Nonlinear Neural Networks for Associative Memories

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Design of BLDCM Driving and Control System for Motorized Treadmill

To satisfy the requirement of developing a new generation of motorized treadmill for a famous domestic manufacturer, a brushless DC motor （BLDCM） driving and control system for motorized treadmill is developed. High integration and reliability of this system are ensured under the condition that intelligent power module （IPM） is used and the protection module is included. Periodic current control method is applied to reduce the average current flowing through the armature winding of the motor when the treadmill is required to start with low speed while large load is added. Piecewise proportion-integration-differentiation （PID） control algorithm is applied to solve the problem of speed fluctuation when impulse load is added. The motorized treadmill of a new generation with the driving and control system has the advantages of high reliability, good speed stability, wide timing scope, low cost, and long life-span. And it is very promising for practical applications.     

Effect of Cu–Al substitution on the structural and magnetic properties of Co ferrites

In this work copper aluminum substituted cobalt nanocrystalline spinel ferrites having general formula Co_1−xCu_xFe_2−x Al_xO₄, with 0.0≤x≤0.8 have been synthesized by using a co-precipitation method. The Cu–Al substituted samples were annealed at 600 °C and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM). XRD analysis confirmed a single phase spinel structure and the crystalline size calculated using Scherrer׳s formula found to be in the range of 14−24 nm. This crystalline size is small enough to achieve the suitable signal to noise ratio in the high density recording media. The FTIR spectra reveal two prominent frequency bands in the wave number range 350–600 cm⁻¹, which confirm the cubic spinel structure and completion of chemical reaction. Magnetic studies reveal that the coercivity (H_c) attains a maximum value of 1142 Oe at 14 nm. The increasing trend of magnetic parameters (coercivity and retentivity) is consistent with crystallinity. The role played by the Cu–Al ions in improving the structural and magnetic properties are analyzed and understood. The optimized magnetic parameters suggest that the material with composition Co_0.6Cu_0.4Fe_1.6Al_0.4O₄ may have a potential application for high density recording media. Our simple, economic and environmental friendly preparation method may contribute towards the controlled growth of high quality ferrite nanopowder, potential candidates for recording.     

Effect of the chemical composition of Cu–In–Ga–Se layers on the photoconductivity and conversion efficiency of CdS/CIGSe solar cells

The effect of the [Ga]/[In+Ga] ratio of gallium and indium on the microwave photoconductivity of Cu–In–Ga–Se (CIGSe) films and on the efficiency of solar cells fabricated in accordance with the same technology is investigated. According to the observations of a field-emission scanning electron microscopy (FESEM), the grain size decreases with increasing Ga content. With increasing gallium content in the samples, the photogenerated-electron lifetime and the activation energy of the microwave photoconductivity also decrease. The changes in the activation energy of the through conduction in darkness are less than 20%. Analysis of the obtained data shows that the known effect of the gallium gradient on the efficiency should be associated with modification of the internal structure of grains instead of with their boundaries.     

Effects of Cu on the interfacial reactions between Sn–8Zn–3Bi–xCu solders and Cu substrate

The microstructure, thermal property, and interfacial reaction with Cu substrate of Sn–8Zn–3Bi–xCu (x = 0, 0.5, 1) lead-free solders were investigated in this work. Cu–Zn intermetallics formed in the solder matrix and the melting temperature increases slightly with Cu addition. After soldering at 250 °C for 90 s, a flat Cu₅Zn₈ layer and a scallop CuZn₅ layer formed at the interfaces of all samples. The CuZn₅ intermetallic compound (IMC) transformed to Cu₅Zn₈ IMC with longer reaction time due to the diffusion of Cu atoms from Cu substrate. The interfacial IMC layer grew thicker with the reaction time following a parabolic law which suggested the interfacial reactions were diffusion controlled. The calculation results show that the activation energy of IMC growth for Cu-containing solders is larger than that of Sn–8Zn–3Bi solder, which demonstrated that a small amount of Cu addition to the solder can effectively suppressed the growth of the interfacial IMC.     

Effect of solder resist dissolution on the joint reliability of ENIG surface and Sn–Ag–Cu solder

The electroless nickel immersion gold (ENIG) process results in surface defects, such as pinholes and black pads, which weaken the solder joint and eventually degrade the reliability of the PCB. Contamination of the plating solutions, including dissolution of the solder resist (SR), can be a cause of the pinholes and black pads. This study examined the effects of SR dissolution on the solder joint reliability and electroless Ni plating properties. Electroless Ni plating was performed by adding 1 to 10 ppm hardener (melamine) to the fresh Ni solution. Many black pads were observed in the 7 and 10 ppm hardener-added surfaces. In addition, the content of P was highest when 7 and 10 ppm hardener was added. The ball shear tests were carried out to confirm the joint reliability between the ENIG surface with hardener-added and the Sn-3.0Ag-0.5Cu solder (SAC 305). The ball shear strength decreased with increasing dissolution of the hardener. In particular, the shear strength was the lowest at 7 and 10 ppm hardener addition. In addition, the failure mode of the solder joint was changed from ductile to brittle mode with increasing hardener addition. That is, as the hardener additive increases, intermetallic compound (IMC) phases were changed from (Cu,Ni)₆Sn₅ to (Cu,Ni)₃Sn₄ and Cu₆Sn₅ (brittle structure).     

Research and Design of Monolithic Decision Circuit for Optical Communication System

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Biomimetic and Biophilic Design of Multifunctional Symbiotic Lichen–Schwarz Metamaterial

Noise and environmental problems are significant issues that affect human beings through the triggering of various stressors, including biological, chemical, physical, and psychological stressors. To address these issues, it is essential to develop environmentally friendly strategies, particularly in the field of materials manufacturing. This study presents a novel biomimetic and biophilic design of a lichen–Schwarz metamaterial (SLSM) that achieves multifunctional properties in noise attenuation and humidity control. The SLSM achieves acoustic and air humidifying multi-functions symbiotically through the use of triply periodic minimal surface (TPMS) and naturally occurring organic lichen. To attain partial or complete sound-blocking capabilities at specific frequencies, a Schwarz meta-symbiont in SLSM requires a parametric design of unit cell characteristics prior to 3D printing. The SLSM structure mimics a biomimetic shell and meta-symbiotic exoskeleton that safeguards the inner symbiont lichen by transitioning it from a dry and brittle state to a hydrated and flexible state during humidity control. The symbiotic lichen in SLSM offers superior sound attenuation across a broader frequency range and adds a unique function of humidity control, which is essential for sustainable architecture and multifunctional furniture in the forthcoming era of buildings.     

Analysis and Design of a ΔΣ Modulator for Fractional-N Frequency Synthesis

提出了一种适用于分数分频锁相环频率综合器的全数字噪声整型 ΔΣ调制器电路结构新的设计方法,并将其最终实现. 采用了流水线技术和新的CST算法优化多位输入加法器结构，从而降低了整体的复杂度和功耗. 这种电路结构通过了Matlab的行为级仿真，ASIC全定制实现并流片，该结构也通过VHDL综合实现验证，最后给出的测试结果表明该电路具有良好的性能，可应用于单片千兆赫兹级低功耗CMOS频率综合器中.