Adjacent Conductors Research Articles

Characterization of the Electric Field Concentration between Two Adjacent Spherical Perfect Conductors

When two perfectly conducting inclusions are located close to each other, the electric field concentrates in a narrow region in between two inclusions and becomes arbitrarily large as the distance between two inclusions tends to zero. The purpose of this paper is to derive an asymptotic formula of the concentration which completely characterizes the singular behavior of the electric field when inclusions are balls of the same radii in three dimensions.

Whisker Growth in Tin Alloys on Glass-Epoxy Laminate Studied by Scanning Ion Microscopy and Energy-Dispersive X-Ray Spectroscopy

Tin-rich solders are widely applied in the electronic industry in the majority of modern printed circuit boards (PCBs). Because the use of lead-tin solders has been banned in the European Union since 2006, the problem of the bridging of adjacent conductors due to tin whisker growth (limited before by the addition of Pb) has been reborn. In this study tin alloys soldered on glass-epoxy laminate (typically used for PCBs) are considered. Scanning ion microscopy with Focused Ion Beam (FIB) system and energy-dispersive X-ray spectroscopy (EDXS) were used to determine correlations between spatial non-uniformities of the glass-epoxy laminate, the distribution of intermetallic compounds and whisker growth.

Detailed Analysis of the Transient Voltage in a JT-60SA PF Coil Circuit

A superconducting coil system is actually complicated by the distributed parameters, e.g. the distributed mutual inductance among turns and the distributed capacitance between adjacent conductors. In this paper, such a complicated system was modeled with a reasonably simplified circuit network with lumped parameters. Then, a detailed circuit analysis was conducted to evaluate the possible voltage transient in the coil circuit. As a result, an appropriate (minimum) snubber capacitance for the Switching Network Unit, which is a fast high voltage generation circuit in JT-60SA, was obtained.

The Simulation Technology Research of Hall Current Sensor

Hall current sensor is a new generation industrial sensors which was widely used in electrical measurement. After introducing the current measurement by hall sensor, the 3D model of current-carrying conductor was built by ANSYS, and the effect caused by current-carrying conductor’s shape and the position of hall sensor was analyzed. Along with the effect of electromagnetic field of adjacent phase current-carrying conductor, the ferromagnetic shield was proposed to reduce this effect and improve the measurement accuracy. The theoretical analysis is verified by the simulation results, which can do a lot in improving the product.

Development of FE-Model for Al 5053 Sheet Plate Forming Using Electromagnetic Force

Magnetic pulse forming is based on the principle of generation of a repulsive force called, Lorentz force due to opposing magnetic fields of adjacent conductors. Magnetic pulse forming of light weight materials such as aluminum, magnesium has been studied by many universities, institutes due to its advantages. But magnetic pulse forming is a complicated research area involving different topics in electromagnetic mechanics, plastic working, and materials mechanics. Therefore, development of FE-model of magnetic pulse forming process is a useful approach for better insight into workpiece deformation mechanics with electromagnetic interaction and further provides design and quality control information. To successfully accomplish this objective, a 3-dimensional ax-symmetric electromagnetic numerical model has been developed. The equation was solved using a general mechanics computer program, ANSYS EMAG and LS-DYNA code.

Exposure of Overhead Conductors to Direct Lightning Strikes: Modeling of Positive Streamer Inhibition

In this paper, it has been shown that a positive upward connecting leader from an overhead conductor spans a considerable part of the lateral attractive distance of the conductor. This justifies the effort to search for means to suppress streamers/upward leaders from such conductors. A new simplified model is introduced to account for the initiation and time growth of glow corona from a cylindrical conductor above ground under linearly rising fields due to cloud charges or negative downward leaders. The model was applied to assess lightning exposure of a streamer-inhibited ground wire as well as its application to lightning protection of adjacent power conductors. The paper confirms the prospect of successful application of streamer inhibition due to space charge shielding (ultra-corona) as a means for lightning protection. Streamer inhibition by using larger conductor diameters or conductors provided with an insulating layer was also considered and the limitations of both techniques were pointed out.

Study of AC Loss Characteristics of HTS-coated Conductor with Magnetic Substrate Using FEM Analysis

A high-T c superconducting (HTS)-coated conductor with a magnetic substrate is promising as a low-cost conductor because Ni alloy can be well texturized by a simple process. However, it has been reported that the magnetism of the substrate makes an AC transport current loss and an AC magnetization loss increase from those losses of the HTS-coated conductor of a nonmagnetic substrate sharply. However, the assembled conductor which bundled many HTS-coated conductors with a magnetic substrate is hardly reported. In this paper, the AC loss and the current distribution in the superconducting layer of the HTS-coated conductor with a magnetic substrate are analyzed using the edge-based hexahedral finite element method (FEM) taking account of both the nonlinear E–J characteristics and the nonlinear magnetic property of the substrate at 77 K. Moreover, AC loss characteristics of HTS-coated conductors with a magnetic substrate arranged with an infinite number of the coated conductors are examined and the effect of the gap length between adjacent conductors on the AC loss is also investigated.

Electrochemical Migration Characteristics of Ag-Plated Cu Powders in Conductive Thick Film

Silver electrochemical migration results in the degradation of surface insulation resistance, and has been attributed to the dendritic bridge between adjacent conductors. In this paper, the electrochemical migration behavior of both Ag-plated Cu powder and pure silver powder in conductive thick film (CTF) are investigated. By Electrochemical migration test (water drop+ DC bias method), and the SEM and XRD examinations, it was found that the silver electrochemical migration in CTF was minimized when the Ag-plated Cu powder substitute silver powder in CTF. This is ascribed to the galvanic coupling effect that plays an important role in the migration inhibition. As sacrifice anode copper restrains the cathodic silver from dissolving in solution so as to decreases the probability of dendritic growth.

Geometric Variability of Nanoscale Interconnects and Its Impact on the Time-Dependent Breakdown of Cu/Low-$k$ Dielectrics

Line edge roughness (LER) and via-line misalignment strongly impact the time-dependent breakdown of the low- k dielectrics used in nanometer IC technologies. In this paper, we investigate, theoretically and experimentally, the impact of the variability of geometry on breakdown. By considering the statistical distribution of thickness between adjacent conductors exhibiting LER, we show that the breakdown location is a function of voltage and occurs at the minimum dielectric thickness at high voltage, but moves to the median thickness at the low voltages. Using these concepts, we show that LER modifies the functional form of failure distributions, and leads to a systematic change in the Weibull with voltage. Accurate reliability analysis requires new reliability extrapolation methodologies to account for these effects. We show that the minimum dielectric thickness present on a test structure or on a circuit is readily determined from routine measurements of dielectric thickness between metal lines. We verify theoretical predictions using measurements of failure distributions of both via and line test structures. Finally, we have shown that LER can significantly modify the apparent field dependence of the failure time, leading to ambiguity in the interpretation of the experimentally determined field dependence.

Effects of crossing saddle coil conductors: Electric length X mutual inductance

AbstractIn magnetic resonance imaging (MRI), either on human or animal studies, the main requirements for radiofrequency (RF) coils are to produce a homogeneous RF field while used as a transmitter coil and to have the best signal‐to‐noise ratio (SNR) while used as a receiver. Besides, they need to be easily frequency adjustable and have input impedance matching 50 Ω to several different load conditions. New theoretical and practical concepts are presented here for considerable enhancing of RF coil homogeneity for MRI experiments on small animals. To optimize field homogeneity, we have performed simulations using Biot and Savart law varying the coil's window angle, achieving the optimum one. However, when the coil's dimensions are the same order of the wave length and according to transmission line theory, differences in electrical length and effects of mutual inductances between adjacent strip conductors decrease both field homogeneity and SNR. The problematic interactions between strip conductors by means of mutual inductance were eliminated by inserting crossings at half electrical length, avoiding distortion on current density, thus eliminating sources of field inhomogeneity. Experimental results show that measured field maps and simulations are in good agreement. The new coil design, dubbed double‐crossed saddle described here have field homogeneity and SNR superior than the linearly driven 8‐rung birdcage coil. One of our major findings was that the effects of mutual inductance are more significant than differences in electrical length for this frequency and coil dimensions. In vitro images of a primate Cebus paela brain were acquired, confirming double‐crossed saddle superiority. © 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 37B: 193–201, 2010

Experimental comparison of traditional and alternating winding method for planar spiral inductor

Two planar winding structures have been built to compare the characteristics of traditional and alternating winding methods. The alternating winding method reduces the potential difference of adjacent conductors, thus reducing substantially the self-capacitance in the winding. Measurements confirmed that the two inductors have similar equivalent inductance and low-frequency series resistance. However, the alternating winding method has a higher self resonant frequency. It is also evident that the reduction of self-capacitance in the winding not only increased the operating bandwidth of the device but also reduced the power losses of the inductor at high frequency.

Blow-up of Electric Fields between Closely Spaced Spherical Perfect Conductors

The electric field increases toward infinity in the narrow region between closely adjacent perfect conductors as they approach each other. Much attention has been devoted to the blow-up estimate, especially in two dimensions, for the practical relevance to high stress concentration in fiber-reinforced elastic composites. In this paper, we establish optimal estimates for the electric field associated with the distance between two spherical conductors in n-dimensional spaces for n ≥ 2. The novelty of these estimates is that they explicitly describe the dependency of the blow-up rate on the geometric parameters: the radii of the conductors.

Low-κ′ dielectric properties of UV-treated bi-axially oriented polypropylene films

A 40 µm multilayer bi-axially oriented polypropylene (BOPP) film, was fabricated by the tenter process and its dielectric response was investigated after applying combined action of UV, humidity and heat. Dissipation factor (tan δ) and relative dielectric constant measurements were performed via the capacitance method for frequencies 20Hz–1 GHz. These results show that the relative dielectric constant (κ′) reduces towards ultra low values (1.8) with an increasing number of applied UV–condensation cycles without any subsequent increase in the dielectric loss. Having no added physical porosity and absence of fluorine atoms, the irradiated BOPP structures offer significant advantages over poly(tetrafluoroethylene) PTFE due to reduced polarization effects, lower dielectric constant values and chemical stability to the adjacent copper or aluminium conductors. Possible application fields are dry type high-voltage capacitors and insulation within electronic components.

Reduction Effect on Magnetization Loss in the Stacked Conductor With Striated and Transposed YBCC Coated Conductor

Recently, it is proposed to make striations on the YBCO coated conductor and to transpose each other as one of the solutions to decrease the perpendicular magnetization loss. For large power application using HTS, the stacked conductor packing the YBCO coated conductors should be used because the current carrying capacity of a single conductor is limited. The stacked conductor has different AC loss characteristics from single conductor because the screening currents in the adjacent conductors affect the local magnetic field at the position of each conductor in the stacked conductors. In this paper, we research the effect by the stack, striation and transposition on magnetization loss of YBCO coated conductors in perpendicular magnetic field. To estimate the reduction effects of perpendicular magnetization loss, several short samples as the stacked conductor with striation and transposition are prepared and tested. We compare the measured results of the conductors with that of the single YBCO coated conductor to estimate the reduction effects.

Filtering applications of a novel cylindrical dielectric core inhomogeneous MTL provided with a sliding conducting ring

AbstractA novel inhomogeneous MTL device consisting of a solid cylindrical dielectric core with four equidistant cylindrical thin wires running along the core's peripheral surface, parallel to the core axis, is examined here from the standpoint of its filtering properties. At the input port of the MTL device three adjacent conductors are bonded together, whereas at the output port the same three conductors are loaded with 50 Ω resistors. For tuning purposes, a conducting ring is made to longitudinally slide along the MTL structure in contact with the MTL wires. Frequency‐domain transfer functions for the output voltages are determined as a function of the sliding ring position. Computed results show that the proposed structure exhibits noticeable selectivity features, controlled by the ring position, which can be used advantageously for filtering applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1815–1818, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24479

EFFECTIVE SKIN DEPTH FOR MULTILAYER COATED CONDUCTOR

Abstract—In this paper, the effective skin depth which provides a useful evaluation for field penetration in multilayer coated conductor is proposed. The reflection on the interface between the adjacent conductors is considered in theoretical derivation. It is found that the effective skin depths of the gold and gold-nickel coated copper rapidly vary with the thickness of the outer layer (gold) when the gold thickness is less than twice the gold skin depth and achieve stabilization as the gold thickness increases to five times the gold skin depth.

The integration of alternative contact cleaning techniques for future DRAM technology nodes

Conventional DRAM contact to Si cleaning methods are using wet HF-based chemistry to remove the native SiO 2 from the contact bottom and reduce the contact resistance [M.R. Baklanov, et al., J. Electrochem. Soc. 145 (9) (1998) 3240–3246]. With further scaling of the contact dimensions the distance between the contacts to the bitline (CB) and the adjacent gate conductors (GC) is decreasing. This is leading to increased parasitic capacitance between the CB and the GC and increased total bitline capacitance. The high bitline capacitance results in large signal delays, poor transfer ratio and thus bad signal margin and worse retention. In addition it is a general limitation for the number of cells attached to this bitline. For future DRAMs the need for small chip size is driving the reduction of the bitline capacitance and keeping the distance between the CB and the GC becomes a critical challenge. Typically, the material separating the CB from the GC is LPCVD TEOS. Furthermore, the selectivity of the wet HF-based chemistry of the as-deposited LPCVD TEOS to thermal SiO 2 is in the order of 3:1. This is resulting in high removal amount of LPCVD TEOS for a given removal of native SiO 2.

Using the Dynamic Behavior of Superimposed Fields for Point-Field-Based Current Sensing

The dynamic behavior of magnetic fields surrounding adjacent current-carrying conductors is investigated for the purpose of point-field-based current sensing. The influence of eddy currents on magnetic field distribution over the useful spectrum (dc to 1 MHz) is quantified by using a spatially dependent metric, the 5% flat bandwidth (FBW). A comparison of field distributions at DC and 1 MHz shows the origin of the FBW function, which is unique to each conductor's cross section and nearby environment. The FBW fields for several different conductor geometries are analyzed. Superposition is used for conductor geometries that have multiple currents. A method for determining optimal field detector placement using optimization functions is introduced.

On the Efficacy of Using Ground Return in the Broadband Power-Line Communications—A Transmission-Line Analysis

The power-line infrastructure has been identified as an efficient system suitable for broadband power-line communication (BPLC) to connect and control various end users. However, the network is affected by stochastic attenuations due to the number of interconnected branches, their line lengths, associated terminal loads, etc. There is yet another parameter that could influence the above stated attenuations or distortions depending on the way the signals are allowed to return to the transmitting end. In this paper, we investigate whether a finitely conducting ground return could be used for BPLC and to investigate its performance over the conventional methods where one of the adjacent power-line conductors is used as signal return. This study could be helpful to those who are proposing the use of ground as a return conductor in BPLC systems. It will be shown that the use of ground return for the BPLC system is effective or better only when the ground conductivity is high (>50 mS/m). When ground conditions are poorer, attenuations increase with frequency, making them unsuitable for BPLC. There are situations where poor ground conditions can still be used but only the transmission-line lengths are shorter. The analysis presented here is based on transmission-line solutions both under lossless (without ground return) and lossy (with ground return) conditions and are applied to typical low-voltage and medium-voltage channels. Comparisons are also made based on the power spectral densities and channel capacities.

Broadband Power-Line Communications: The Channel Capacity Analysis

The power line has been proposed as a solution to deliver broadband services to end users. Various studies in the recent past have reported a decrease in channel capacity with an increase in the number of branches for a given channel type whether it is an indoor or low-voltage (LV) or medium-voltage (MV) channel. Those studies, however, did not provide a clear insight as to how the channel capacity is related to the number of distributed branches along the line. This paper attempts to quantify and characterize the effects of channel capacity in relation to the number of branches and with different terminal loads for a given type of channel. It is shown that for a power spectral density (PSD) between 90 dBm/Hz to 30 dBm/Hz, the channel capacity decreases by a 20-30 Mb/s/branch, 14-24 Mb/s/branch, and a 20-25 Mb/s/branch for an MV channel, LV channel, and indoor channel, respectively. It is also shown that the channel capacity is minimum when the load impedance is terminated in characteristic impedances for any type of channel treated here. It is shown that there could be a significant loss in channel capacity if a ground return was used instead of a conventional adjacent conductor return. The analysis presented in this paper would help in designing appropriate power-line communication equipment for better and efficient data transfer.