Galvanic Contact Research Articles

Comparative Study of Chloride and Fluoride Induced Aluminum Pad Corrosion in Wire-Bonded Device Packaging Assembly

The introduction of copper as wire bonding material brings about a new challenge of aluminum bond pad bimetallic corrosion at the copper/aluminum galvanic interface. Aluminum is well known to undergo pitting corrosion under halide-contaminated environments, even in slightly acidic conditions. This paper aims to study the corrosion morphology and progression of aluminum influenced by different halide contaminations in the presence and absence of galvanic contact with copper. We used a new corrosion characterization platform of the micropattern corrosion screening to simulate the copper wire bonding on the aluminum bond pad. The corrosion screening data and subsequent SEM–EDX analyses showed a striking difference in morphology and progression between chloride-induced and fluoride-induced aluminum corrosion. The corrosion products formed play a vital role in the resulting morphology and in sustaining further aluminum corrosion.

A 110–170-GHz Non-Galvanic Interface for Integrating Silicon Micromachined Chips With Metallic Waveguide Systems

We report on the development of a non-galvanic transition from a silicon micromachined to metallic rectangular waveguide for use in integrated waveguide systems at D-band (110-170 GHz). This transition overcomes the limitations of current solutions that require proper ohmic (galvanic) contact between both waveguides, and thus relaxes tolerance requirements in assembly and manufacturing. The transition uses an in-plane design which enables low-loss integration of micromachined waveguide components, as it eliminates the need for waveguide bends and complex multi-layer structures. We describe the RF design, analyze the EM simulation results, and explain the operating principle of the transition. To verify the concept, dedicated silicon micromachined and metallic waveguides are designed and fabricated. Characterization of the assembled samples shows good agreement with simulation. The transition achieves a typical insertion loss of 0.3 dB and return loss above 20 dB over most of the D-band. Measurement of multiple samples and repeated assemblies results in a variation of S21 of less than ±0.1 dB over the whole band, demonstrating good robustness and repeatability. By removing the need for galvanic connection, automated tools can then be used during system assembly, which enables industrial scale applications such as wireless communications.

Dual-Polarized Dual-Loop Double-Slot Antipodal Tapered Slot Antenna for Ultra-Wideband Radar Applications

The miniaturized high-gain antenna is required in portable, ultra-wideband radar systems. However, the miniaturization, ultra-wideband and high gain often restrict each other in the antenna design. In this paper, a dual-polarized, double-slot, antipodal tapered slot antenna with a double-layer, dual-loop structure and novel slot edges is presented. The proposed magnetic dual-loop structure has the capacity to reduce the low cut-off frequency of the double-slot tapered slot antenna by weakening the resonance and coupling. In addition, the high gain, low sidelobe level (SLL), and low cross-polarization level are achieved in the boresight direction. A novel gradient slot profile is designed to improve the low-frequency directivity of the tapered slot antenna without affecting the matching. To feed the antenna elements, a kind of wideband, balun-divider structure is designed. The dual-polarized antenna is combined by two orthogonal elements in a cross configuration without galvanic contact or influence to performance. The measured results show that the impedance bandwidth of the proposed antenna is 0.6~4 GHz, and the maximum gain is 11 dBi. The isolation between the two antenna ports is better than 32 dB, and the cross-polarization discrimination (XPD) is better than 20 dB.

Superconducting qubits in a flip-chip architecture

Flip-chip architectures have recently enabled significant scaling-up of multi-qubit circuits and have been used to assemble hybrid quantum systems that combine different substrates, for example, for quantum acoustics experiments. The standard flip-chip method uses superconducting galvanic connections between two substrates, typically implemented using sophisticated indium wafer-bonding systems, which give highly reliable and temperature-cyclable assemblies, but are expensive, somewhat inflexible in design, and require robust substrates that can sustain the large compressive forces required to cold-weld the indium bonds. A much simpler method is to assemble dies using very low-force contacts and air-dried adhesives, although this does not provide a galvanic contact between the dies. Here, we demonstrate that the latter technique can be used to reliably couple superconducting qubit circuits, in which the qubits are on separate dies, without the need for a galvanic connection. We demonstrate full vector qubit control of each qubit on each of the two dies, with high-fidelity single-shot readout, and further demonstrate entanglement-generating excitation swaps as well as benchmark a controlled-Z entangling gate between the two qubits on the two dies. This exemplifies a simple and inexpensive assembly method for two-plus-one-dimensional quantum circuit integration that supports the use of delicate or unusually shaped substrates.

Fabrication of low-cost Ni-P composite coating on Mg alloys with a significant improvement of corrosion resistance: Critical role of mitigating the galvanic contact between the substrate and the coating

High galvanic corrosion susceptibility and expensive Pd-activation process are two critical obstacles for the application of electroless nickel (EN) plating on Mg alloy. In this work, the plasma electrolytic oxidation (PEO) coating was sealed by chemical conversion post-treatment to obtain an intermediate layer with high electrical resistance, aiming to minimize the susceptibility of galvanic corrosion. A low-cost Ag-activation technique was proposed to catalyze the EN plating process. Results indicate a dramatic improvement of corrosion resistance of EN composite coating. In addition, the composite coating also exhibits high adhesion, hardness, electrical conductivity and low magnetism.

Electrical and Electromagnetic Geophysical Prospecting for the Monitoring of Rock Glaciers in the Dolomites, Northeast Italy.

The monitoring of rock glaciers plays a relevant role in relation to natural hazards in high mountain environments. Due to the climate warming, mountain permafrost is thawing, and its degradation is influencing the triggering and the evolvement of processes such as rockfalls, landslides, debris flows and floods. Therefore, the study and monitoring of these periglacial forms have both a scientific and economic importance. We tested electrical and electromagnetic measurements along the same investigation lines, in two different sites of the Dolomites area (Northeast Italy). Electrical prospecting exploits the high resistivity contrast between frozen and non-frozen debris. However, these measurements have high logistic demands, considering the complex rock glaciers surface and the need of ground galvanic contact. For this reason, we tried to compare electrical measurements with electromagnetic contactless ones, that theoretically can be used to define the distribution of electrical resistivity in the first subsoil in a quicker and easier way. The obtained results show that the joint use of the two methods allows us to characterize a rock glacier subsoil with good confidence. Finally, the advantages and disadvantages of both the techniques are discussed.

Non-contact capacitive sensing for ECG recording in small animals

Rat electrocardiography (ECG) is frequently used in biomedical research as a model for exploring heart function in a wide variety of experimental conditions. Subcutaneous ECG is a common approach to record rat heart rhythm using implanted needle electrodes to sense the rat ECG signals with the animal under deep anesthesia. However, such an invasive measurement could cause inconvenience due to cumbersome animal preparation, and the anesthetics are likely to interfere with the autonomic regulation of cardiac rhythm. Most studies used the galvanic contact between animal limb and electrode sensing surface to record cardiac signals from small animals. However, the non-contact approach of capacitive ECG sensing for small laboratory animals has not been extensively investigated. This study aims to develop a non-contact ECG system to promote the ECG measurement of laboratory animals for biomedical research. The method utilizes the capacitive coupling technique to detect cardiac signals in awake rats (R-wave amplitude of only 0.2 mV) through a non-conductive layer. The proposed system generates non-contact ECG signals with distinguishable R-peaks at a limb-electrode capacitance above 8.5 pF and maximum through-thickness of the non-conductive layer of 0.4 mm for heart rate assessment. In conclusion, this study provides non-contact ECG monitoring based on capacitive electrodes to improve the throughput of ECG measurement procedures for biomedical research and establish a lower bound of coupling capacitance for non-contact application to heart rate. The new method is ideally suited for the rapid evaluation of autonomic regulation of heart rhythm in awake laboratory small animals.

Protection Coordination of AC/DC Intersystem Faults in Hybrid Transmission Grids

The new characteristics and phenomena of hybrid AC/DC transmission grids challenge the conventional protection concepts. In hybrid AC/DC overhead line systems, AC and DC systems are located on the same support structure. As a result, electromagnetic and galvanic interactions between the AC- and the DC-line influence the AC-protection and the DC-control in a novel and complex way. This paper presents key findings and solutions from a current 400-kV-hybrid AC/DC overhead line project in Germany. The focus is on AC/DC intersystem faults, i.e. galvanic contact between DC and AC systems. Fault detection and fault response of the AC-protection and the DC-control as well as a proper AC/DC protection coordination are discussed. The paper illustrates the challenges of a secure and dependable fault clearing and indicates solution methods. The findings of this paper are based on EMT simulations with detailed PSCAD-models of the hybrid AC/DC overhead line and the VSC-converters. Laboratory protection tests have been conducted and confirmed the results.

Effects of NaCl Concentration and Solution Temperature on the Galvanic Corrosion between CFRP and AA7075T6

To reduce structural weight, light metals, including aluminum and magnesium alloys, have been widely used in various industries such as aircraft, transportation and automobiles. Recently, composite materials such as Carbon Fiber Reinforced Plastics (CFRP) and Graphite Epoxy Composite Material (GECM) have also been applied. However, aluminum and its alloys suffer corrosion from various factors, which include aggressive ions, pH, solution temperature and galvanic contact by potential difference. Moreover, carbon fiber in CFRP and GECM is a very efficient cathode, and very noble in the galvanic series. Galvanic contact between carbon fiber composites and metals in electrolytes such as rain or seawater, is highly undesirable. Notwithstanding the potentially dangerous effects of chloride and temperature, there is little research on galvanic corrosion according to chloride concentration and temperature. This work focused on the effects of chloride concentration and solution temperature on AA7075T6. The increased galvanic corrosion between CRFP and AA7075T6 was evaluated by electrochemical experiments, and these effects were elucidated.

Partial Discharge Detection and Localization: Using Software-Defined Radio

Partial discharge (PD) occurs when insulation containing voids is subjected to high voltage (HV). If left untreated, PD can degrade insulation until, eventually, catastrophic insulation failure occurs. The detection of PD current pulses, however, can allow incipient insulation faults to be identified, located, and repaired prior to plant failure. Traditionally, PD is detected by using galvanic contact methods or capacitive/inductive coupling sensors. This article discusses the use of software-defined radio (SDR) for PD detection and localization and presents proof of principle experimental results that suggest that SDR can provide a simple and reliable solution for PD-based monitoring of HV insulation integrity.

Ultra-wideband 1–20 GHz Non-contact FMR Test System for TMR HGA

The read sensor of hard disk drive abnormality at the bar level is detected by a ferromagnetic resonant analyzer (FMRA) system requiring a galvanic contact to the sensor. After the read head is assembled to the slider, a quasistatic tester is used to check the slider functionality. At this stage, the FMR information of the read sensor cannot be easily accessed since there is no suitable measurement technique available. In this research, an innovative non-contact ferromagnetic resonant (FMR) measurement for the read head sensor quality control at slider level is reported for the first time. The proposed test system is designed for detecting the FMR from 1 to 20 GHz. The FMR is interpreted from the peak of read sensor resistance over the frequency span. This new measurement technique has been applied to a model of tunneling magnetoresistance (TMR) sensor and compared with the FMRA. The FMR frequency at 5.4 GHz can be detected by the proposed measurement system with only 1 MHz difference from the value obtained from conventional FMRA. The higher effective stiffness field of the read sensor is also observed from the lower FMR resistance in the shorter stripe height head.

Compact Integrated Full-Duplex Gap Waveguide-Based Radio Front End For Multi-Gbit/s Point-to-Point Backhaul Links at E-Band

This paper presents the design and realization of a high data rate radio front-end module for point-to-point backhaul links at E-band. The design module consists of four vertically stacked unconnected metal layers without any galvanic and electrical contact requirements among the building blocks, by using gap waveguide technology. The module components are a high-gain array antenna, diplexer, and circuitry consisting of a transmitter (Tx) and a receiver (Rx) monolithic microwave integrated circuits (MMICs) on a carrier board, which is successfully integrated into one package with a novel architecture and a compact form. The diplexer consists of two direct-coupled cavity bandpass filters with channels at 71–76 GHz and 81–86 GHz with a measured return loss of 15 dB and an isolation greater than 50 dB. A wideband $16\times 16$ slot array antenna with a measured gain of more than 31 dBi is used to provide high directivity. The measured results show that the packaged transmitter provides a conversion gain of 22 and 20 dB at 76 and 86 GHz, respectively, with an output power of 14 and 16 dBm at 1-dB gain compression point, at the same frequencies. The packaged receiver shows an average conversion gain of 20 dB at 71–76-GHz and 24 dB at 81–86-GHz bands. A real-time wireless data transmission is successfully demonstrated with a data rate of 8 Gbit/s using 32-quadrature amplitude modulated signal over 1.8-GHz channel bandwidth with spectral efficiency of 4.44 bit/s/Hz. The proposed radio front end provides the advantages of low loss, high efficiency, compact integration, and a simple mechanical assembly, which makes it a suitable solution for small-cell backhaul links.

A Noncontact Voltage Measurement System for Power-Line Voltage Waveforms

This paper presents the design and implementation details of a complete noncontact (NC) voltage acquisition system, which allows the measurement of power-line voltage waveforms without galvanic contact. The system is composed by a novel capacitive probe, an analog front end (AFE), and a microcontroller-based digital signal processing stage. A deep experimental characterization of the noncontact measurement system was performed. The tests reported a high linearity (maximum nonlinearity of ±0.2%), a low input-referred noise (11 mVrms), and a low-frequency response distortion. Measurements of ±330-V triangular waveform signals were performed with maximum instantaneous errors below ±1.5 V. The power-line voltage (220 Vrms at 50 Hz) was acquired without galvanic contact with an instantaneous error lower than ±3 V, whereas the mean error on rms voltage measurements was 0.32% and the maximum 0.7%. A two-day continuous measurement of power-line voltage was accomplished for testing system’s stability, resulting in negligible accuracy variations.

About Modeling Kinematic Parameters of Deposition from Composite Electrochemical Coatings for Restoration of Details for Agricultural Machines

Theoretical aspects of process of drawing of composite galvanic coverings on the basis of a chromic matrix on current-carrying surfaces are considered by method of galvanic contact plating (GCP). The analytical dependences connecting parameters of physic mechanical characteristics of a covering with technological modes of sedimentation of coverings and design features of the equipment, used in process are resulted.

Galvanic Interactions of 15CDV6/MDN138 & 15CDV6/MDN250 Alloys in Natural Seawater

The galvanic corrosion behavior of the metal combinations 15CDV6/MDN138 and 15CDV6/MDN250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI’s Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN138, MDN250, and 15CDV6 of the individual metal, the galvanic potential and galvanic current of the couples 15CDV6/MDN138 and 15CDV6/MDN250, were periodically monitored throughout the study period. The calcareous deposits on MDN138 and MDN250 in galvanic contact with 15CDV6 were analyzed using XRD. The electrochemical behavior of MDN138, MDN250, and 15CDV6 in seawater was studied using an electrochemical work station. The surface characteristics of MDN138 and MDN250 in galvanic contact with 15CDV6 have been examined with a scanning electron microscope. The results of the study reveal that the galvanic protection offered by 15CDV6 to MDN250 and MDN138 in natural seawater amounts to 93% and 98%, respectively, implying that the galvanic protection offered by 15CDV6 is continuous and effective, which has been further evinced from the adherent nature of the calcareous deposit film comprising compounds such as CaCO3 (calcite, aragonite, and vaterite), MgCO3 (magnesite), Mg(OH)2 (brucite), and MgO (brucite).

Galvanic-submerged photosynthesis of crystallites: Fabrication of ZnO nanorods@ Cu-surface

Abstract In this study, we report a facile fabrication method of 1-D ZnO nanorods (NRs) on a copper substrate surface by means of galvanic contact reactions. Instead of using bimetallic aqueous solution for the galvanic reactions, UV illumination on the Zn contacted with Cu surface in pure water environment was implemented, leading to galvanic combined submerged photo-synthesis of crystallites (G-SPSC) process. A pencil-like and flat-tip shape of NRs growth can be controlled as a function of UV irradiation time. In order to grow fine NRs, the galvanic process was essential for Zn2+ and OH− ions production. In particular, OH− accumulated at the vicinity surface of Cu to achieve a locally alkaline environment. Then, UV irradiation assisted the ZnO NRs initiated by water splitting process. Oxygen vacancy (VO) was responsible for the growth of pencil-like shape NRs. A blue shift in visible light region of photoluminescence (PL) spectra was observed when the pencil-like NRs transformed into flat-tip shape. The successful heterojunction of ZnO-Cu also was observed in their PL spectra, which dictated by the formation of zinc antisite (ZnO). The G-SPSC method approach is versatile for other bimetallic system adaptation and is promising for large-scale environmentally friendly synthesis of optoelectronic devices.

Nonintrusive Energy Meter for Nontechnical Losses Identification

We present in this paper a method and apparatus for nonintrusive measurement of active energy in low-voltage ac installations. In the proposed method, the active power is calculated from the voltage and current waveforms, and the phase shift between them. No voltage amplitude measurement is required since the nominal voltage of the ac installation is considered as the actual voltage. This approach bypasses the main disadvantage of capacitive ac voltage probing: low accuracy in amplitude measurements due to variations on the sensor coupling capacitance. The energy meter that implements the technique is composed of a commercial nonintrusive current sensor (clamp-on current transformer) and a contactless capacitive voltage sensor—designed to measure the voltage phase and waveform. The voltage sensor includes a shield to isolate it from external electric fields, making the energy meter suitable for applications in polyphase systems. The developed energy meter does not require on-site calibration, galvanic contact to the phase conductors, neither electrical circuit opening, allowing for quick, safe, and easy installation on overhead service drop line. Due to these characteristics, it can be used by electricity distribution companies in the preinspection of consumer units suspected of fraud. Experimental results proved that the developed energy meter is insensitive to the characteristics of cables (width and insulation), external electrical fields, as well as to the voltage sensor capacitance variations. The error of the active energy measurement under real condition in a two-phase installation was 1%.

A 400 GΩ Input-Impedance Active Electrode for Non-Contact Capacitively Coupled ECG Acquisition With Large Linear-Input-Range and High CM-Interference-Tolerance.

Electrocardiogram (ECG) is one of the major physiological vital signs and an effective monitoring method for patients with cardiovascular diseases. However, existing ECG recordings require a galvanic body contact, which is unpractical in daily life. This paper presents the design of an ECG chip that facilitates non-contact ECG recording through capacitive coupling. With the input impedance boosting techniques, as well as an active driven-right-leg (DRL) which boosts common-mode rejection ratio to 70dB, the single-ended capacitive feedback active electrode (AE) achieves ultra-high input impedance of 400 GΩ (< 0.5 Hz), a large common-mode interference tolerance (2.8 VPP), and a high linear-input-range (220 m VPP). Implemented in 0.18 μm 5V CMOS process, the prototype occupies an area of 1.23 mm2, and consumes 18 μA and 13 μA for the AE and DRL, respectively. Real life non-contact capacitively coupled ECG acquisition has been demonstrated, obtaining ECG waves and heart rate in the presence of motion artifacts as well as ambient interference.

Simultaneous measurement of multiple soil properties through proximal sensor data fusion: A case study

In this research, proximal soil sensor data fusion was defined as a multifaceted process which integrates geospatially correlated data, or information, from multiple proximal soil sensors to accurately characterize the spatial complexity of soils. This has capability of providing improved understanding of soil heterogeneity for potential applications associated with crop production and natural resource management. To assess the potential of data fusion for the purpose of improving thematic soil mapping over the single sensor approach, data from multiple proximal soil sensors were combined to develop and validate predictive relationships with laboratory-measured soil physical and chemical properties. The work was conducted in an agricultural field with both mineral and organic soils. The integrated data included: topography records obtained using a real-time kinetic (RTK) global navigation satellite system (GNSS) receiver, apparent soil electrical conductivity (ECa) obtained using an electromagnetic induction sensor, and content of several naturally occurring radioisotopes detected using a mobile gamma-ray spectrometer. In addition, the soil profile data were collected using a commercial ruggedized multi-sensor platform carrying a visible and near-infrared (vis-NIR) optical sensor and a galvanic contact soil ECa sensor. The measurements were carried out at predefined field locations covering the entire study area identified from sensor measured a priori information on field elevation, ECa and gamma-ray count. The information was used to predict: soil organic matter (SOM), pH, lime buffer capacity (LBC), as well as concentration of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and aluminum (Al). Partial least squares regressions (PLSRs) were used to predict soil properties from individual sensors and different sensor combinations (sensor data fusion). By integrating the data from all of the proximal soil sensors, SOM, pH, LBC, Ca, Mg, and Al were predicted simultaneously with R2 > 0.5 (RPD > 1.50). Improved predictions were observed for most soil properties based on sensor data fusion than those based on individual sensors. After choosing the optimal sensor combination for each soil property, the predictive capability was compared using different data mining algorithms, including support vector machines (SVM), random forest (RF), multivariate adaptive regression splines (MARS), and regression trees (CART). Improved predictions for SOM, Ca, Mg, and Al were observed using SVM over PLSR. The predictive capability was followed by RF and MARS, with CART. Predictions of pH and LBC were only feasible using MARS and PLSR, respectively. In this field, it was not possible to predict extractable P and K using all tested sensor combinations or algorithms. With large variability in SOM, the field presents a special situation and thus, the result could be specific to the study site. Further research includes an extended number of experimental sites covering different geographic areas around Eastern Canada.

Characterization of High-$Q$ Inductors Up to its Self-Resonance Frequency for Wireless Power Transfer Applications

The primary coil of an efficient asymmetric inductive link (IL) has a high quality factor and operates near its self-resonance frequency (SRF). Therefore, its characterization is challenging, especially because the measurement instruments must be able to measure a large reactance and a very small resistance at a frequency where the inductor radiates. In this letter, we present a method suitable for characterizing high- $Q$ inductors up to its SRF. The proposed method uses an inductive sensor to characterize the inductor under test without galvanic contact. The method was validated by applying it to the primary coil of an asymmetric IL. The empirical results are consistent with the theoretical model and the full-wave simulations.