Electrical Interconnects Research Articles

Market Design for Cross-Border Co-Optimised Energy-Reserve Allocation

To achieve its energy goals, the European Union (EU) needs to establish a geographically large market by initially improving its cross-border electricity interconnections. The Hungarian project focuses on this topic. A geographically large market, based on imports and exports of electricity, could increase the level of competition, boost the EU’s security of electricity supply through creating alternative routes to the customers and integrate more renewables into energy markets. Electricity should, as far as possible, flow between Member States as easily as it currently flows within Member States, in order to increase sustainability potential and real competition, as well as to drive economic efficiency of the energy system. To this end, Facilitating Regional CROSS-border Electricity Transmission (FARCROSS) aims to address this challenge by connecting major stakeholders of the energy value chain and demonstrating integrated hardware and software solutions that will facilitate the “unlocking” of the resources for the cross-border electricity flows and regional cooperation. The targets of the project are to optimise the usage of the available cross-border capacity for reserve procurement while transitioning from ATC to Flow-based mechanism, to achieve simultaneous interconnector reservation for energy and balancing capacity to enable reserve market coupling and to create state-of-art technologies to materialise market coupling platforms.

Technical versus socio-economic and environmental criteria in power transmission projects

In recent years, the efforts of countries to reach agreements on the development of cross-border electricity interconnection have intensified because they optimize energy resources and constitute the most significant instantaneous support for the security and continuity of electricity supply. In addition, interconnections play a key role in the integration of electricity markets. However, the planning of European electricity infrastructures constitutes complex analyses due to the large number of factors involved. This article applies a multicriteria methodology for the evaluation and prioritization of cross-border interconnection projects with the simulation of different scenarios, in total 12 scenarios, to study the effect of changes in the selected criteria on the results obtained. To test the defined methodology, the variation in the weight of different criteria in the assessment of a new cross-border electrical interconnection project between Spain and France is studied. It was verified that the tool is coherent and that the analysis developed improves the understanding of such large and complex projects and can facilitate the prioritization of project portfolios with a clear and explicit method.

Applications and prospects of machine learning for aerosol jet printing: A review

Aerosol Jet Printing (AJP) is an additive manufacturing process that deposits ink-like materials suspended as an aerosol mist. AJP creates three-dimensional (3D) functional structures onto flat or conformal surfaces in complex shapes without the aid of additional tooling, enabling the manufacturing of extremely fine electrical interconnects with freeform structures. Due to the novelty and complexity of AJP, physical understanding is rather limited, hindering physics-based process modeling and analysis. Fortunately, the data resources from AJP applications, e.g., 3D Computer-Aided-Design data, Standard Triangle Language files, in-situ images of part, and nozzle motion records, provide an unparalleled opportunity for developing data-driven, Machine Learning (ML) methods to characterize AJP processes, support process control, and facilitate product improvement. To thoroughly identify the newfound opportunities, this study reviews state-of-the-art ML methods used in AJP applications, investigates open issues in AJP, and outlooks future development of ML-based research topics for AJP. It sheds light on how to maximize the value of ML on AJP data to develop scalable, generalizable decision-making methods. More future works along the direction will be motivated.

Carbonization-Temperature-Dependent Electrical Properties of Carbon Nanofibers-From Nanoscale to Macroscale.

An exact understanding of the conductivity of individual fibers and their networks is crucial to tailor the overall macroscopic properties of polyacrylonitrile (PAN)-based carbon nanofibers (CNFs). Therefore, microelectrical properties of CNF networks and nanoelectrical properties of individual CNFs, carbonized at temperatures from 600 to 1000 °C, are studied by means of conductive atomic force microscopy (C-AFM). At the microscale, the CNF networks show good electrical interconnections enabling a homogeneously distributed current flow. The network's homogeneity is underlined by the strong correlation of macroscopic conductivities, determined by the four-point-method, and microscopic results. Both, microscopic and macroscopic electrical properties, solely depend on the carbonization temperature and the exact resulting fiber structure. Strikingly, nanoscale high-resolution current maps of individual CNFs reveal a large highly resistive surface fraction, representing a clear limitation. Highly resistive surface domains are either attributed to disordered highly resistive carbon structures at the surface or the absence of electron percolation paths in the bulk volume. With increased carbonization temperature, the conductive surface domains grow in size resulting in a higher conductivity. This work contributes to existing microstructural models of CNFs by extending them by electrical properties, especially electron percolation paths.

Efficient Monolithic Perovskite/Silicon Tandem Photovoltaics

Tunable bandgaps make halide perovskites promising candidates for developing tandem solar cells (TSCs), a strategy to break the radiative limit of 33.7% for single‐junction solar cells. Combining perovskites with market‐dominant crystalline silicon (c‐Si) is particularly attractive; simple estimates based on the bandgap matching indicate that the efficiency limit in such tandem device is as high as 46%. However, state‐of‐the‐art perovskite/c‐Si TSCs only achieve an efficiency of ~32.5%, implying significant challenges and also rich opportunities. In this review, we start with the operating mechanism and efficiency limit of TSCs, followed by systematical discussions on wide‐bandgap perovskite front cells, interface selective contacts, and electrical interconnection layer, as well as photon management for highly efficient perovskite/c‐Si TSCs. We highlight the challenges in this field and provide our understanding of future research directions toward highly efficient and stable large‐scale wide‐bandgap perovskite front cells for the commercialization of perovskite/c‐Si TSCs.

Функциональное формирование нейроморфного резервуарного вычислительного элемента на базе мемристивного метаматериала

A neural network structure is designed based on the ability of a certain class of calculators to recombine internal resources in order to produce neuromorphic elements to solve applied problems. This approach is rooted in a composite material with controlled local conductivity to form volumetric inhomogeneities capable of responding to and influencing external electrostatic effects. Such compounds aggregate into stable clusters suitable for modelling the processes that occur during information processing in natural neuronal entities. The use of conductive transitions between substrate-formed neuromorphic clusters as a learning structure makes it possible to increase the reliability of the neural network system. Long-term, non-volatile storage of information about the elements of the training sample in variable structures is possible. The basic approach to information conversion is to manage the electrostatic influence as it passes through the layered structures formed. The response to the input is not formed by propagating the signal through conductive elements with variable conductivity, but by passing the energy impact through a limited volume of metamaterial. Thus, a massively parallel processing of information can be achieved with the implementation of a mechanism for combining the opinions of independent neural network clusters that influence the final decision. Furthermore, this method of spreading effects in such an environment greatly simplifies the process of adding elements to the neural network. The lack of direct electrical interconnection facilitates the easy addition of new computational elements without significant rearrangement of the conductive media. Networks of this type are capable of significant growth without loss of experience. The input conversion process using modified delta coding prevents premature wear and tear on reconfigurable network elements. The manner in which information is presented and the manner in which neural network computing is organised enabled the creation of limited autonomous oscillations within the volume of the calculator to maintain circulating memory and the ability to gradually accumulate network experience for its subsequent recording in configurable elements. The identified features resulted in the application of this kind of calculators in the task of developing radio frequency management plans for the organisation of stable communication in a complex electromagnetic environment.

Assessing the national synergy potential of onshore and offshore renewable energy from the perspective of resources dynamic and complementarity

Intermittent renewable energy sources have been transformed from supplementary energy to dominant incremental alternative energy sources in the context of carbon neutrality target worldwide. For coastal countries, it is urgent to integrate abundant offshore energy into regional onshore renewable power sources economically and reliably considering the scarcity of land resources and negative environmental impacts. However, limited knowledge on the complex spatiotemporally synergy relationships between energy potential (onshore and offshore) is a barrier in making reasonable policies to promote collaborative development of onshore and offshore energies. This study presents a spatiotemporally explicit modelling framework for assessing the synergy potential characteristics of onshore and offshore renewable energy sources. The framework firstly estimates the technical potential of solar PV and wind energy across the country by using 40 years of hourly meteorological reanalysis data (1980–2020), and then investigates the long-term changes trend, stability, and complementarity of solar-wind energy potential spatiotemporally at both onshore and offshore sub-regions. We find that a considerable amount of solar PV and wind energy sources could be harnessed in China, and onshore potential across the country (178 PWh/yr) is approximate 20 times higher than offshore energy potential (8.9 PWh/yr). Overall, onshore solar-wind energy potentials exhibit statistically insignificant but slightly increasing trend over the past 40 years, while offshore wind potentials observe an opposite change trend for solar PV and wind energy production. Complementarity assessment showed the northeast and offshore parts of China present high complementarity effects for hourly and daily power production of solar-wind systems. Furthermore, inter-regional combination between offshore and onshore northwest regions also exhibits promising synergy effect for renewable energy power output. The results on resources dynamic and complementarity highlight the advantage of interregional resources cooperative configuration and electric power grid interconnections. The analysis performed in this paper could provide a global picture for the integration planning and collaborative development strategies formulation of on-/offshore renewable energy across the country.

Flexible Thermoelectric Devices with Flexible Heatsinks of Phase-Change Materials and Stretchable Interconnectors of Semi-Liquid Metals.

Flexible thermoelectric (TE) devices offer great potential for wearable thermal management and self-powered systems, but heat dissipation and electrical interconnection remain key challenges. In this study, we address these issues by integrating flexible TE devices with phase-change material (PCM) heatsinks and stretchable semi-liquid metal (semi-LM) interconnectors. The effectiveness of PCMs with varying melting points for temperature regulation in different environmental conditions is demonstrated, delivering cooling effects exceeding 10 °C. Furthermore, the utilization of semi-LMs instead of LMs enables excellent stretchability and efficient heat dissipation. Moreover, the TE devices generate power with a density of 7.3 μW/cm2 at an ambient temperature of 22 °C, making it an ideal power source for a wearable self-powered sensing system. Successful integration into garments and armbands confirms the practicality and adaptability of these flexible thermoelectric devices, establishing them as critical components for future wearables with superior resilience to daily wear and tear.

High-Tolerance Thin-Film Solder Joints for Electrical Interconnection in Harsh Environments

This paper presents a pioneering use of thin-film solder joint in the electrical interconnection of high-temperature thin-film sensors, which aims to improve the low tolerance of traditional soldered balls in extreme environments. The structure of the thin-film solder joint, composed of silver foil, solder joint paste, and metal wire, has a negligible mass compared to traditional soldered balls. As a result, the inertia force on the solder joint/substrate interface during vibration and force impact is greatly reduced, improving the reliability of the solder joint under thermal-mechanical coupling impacts. The thin-film solder joint has been verified using both metal (AgPd paste) and ceramic (TiB2/SiCNO paste) solders, and can withstand extreme environments such as thermal shock and high "g" loading. The designed thin-film solder joint can withstand impact energy of up to 3 J at 1000 °C without failure, which is 6 times higher than that of traditional soldered balls (with a statistical failure rate of up to 67% under 0.5 J impact). The thin-film solder joint was successfully used for electrical interconnection of high-temperature thin-film strain gauges, demonstrating excellent reliability under thermal-mechanical coupling impacts at 1000 °C. Our high-tolerance thin-film solder joints show promising potential for use in electrical interconnection in harsh environments.

Flip-Chip Bonding of InP Die on SiN-Based TriPleX Carrier With Novel Laser Soldering

In this paper, we present a flip-chip bonding concept for InP die on SiN-based TriPleX carrier using laser soldering. The InP die and SiN-based TriPleX carrier include the metalization patterns for commonly used photonic integrated circuit reference designs. Two laser soldering schemes were investigated: (1) using a laser wavelength where silicon is highly transmissive (through-silicon laser soldering) and (2) using a laser wavelength where silicon is not transmissive (heat-conduction laser soldering). We demonstrated a 4.0 mm × 4.6 mm InP die with 58 electrical connections flip-chip bonded on a 16.0 mm × 8.0 mm SiN-based TriPleX carrier. Comparison experiments were carried out including solder reflow and shear force tests. Both schemes showed reliable electrical interconnects that meet MIL-STD 883 standards. Especially, the through-silicon soldering showed faster soldering time, lower power for solder reflows, and less thermal impact which is therefore preferred over heat-conduction soldering. This concept is promising for a high-density, reliable interconnect of hybrid packaging of InP on SiN-based photonic integrated circuits, in particular large photonic dies.

Analysis of the Policy of Moving the National Capital (IKN) with an Energy Increase Strategy: Readiness of Economic and Public Administration Aspects

This article examines the policy of moving the National Capital (IKN) from Jakarta Province to East Kalimantan Province with an energy improvement strategy based on readiness from economic and public administrative aspects. The theory used is agenda-setting theory with descriptive qualitative research methods. The results show that the policy analysis of moving IKN from Jakarta to East Kalimantan can be reviewed based on readiness in economic and public administrative factors. In public administration, the policy of moving IKN to East Kalimantan Province can adjust the concept of a smart city, green city, and international standard. East Kalimantan Province has a diverse economy, with small and medium-sized businesses, fishing, agriculture, plantations, mining, and services all present. Energy improvement strategies include building natural gas transmission networks, bolstering the electrical interconnection transmission network, building large-scale hydropower plants, building installations, and clean energy, and putting energy in place energy-efficient transportation systems. It can be used to optimize these economic aspects. The emission-free idea, the PLTS system's organization, and a public administration system based on technology and information are all necessary proposals to make it simpler for staff members to serve the community.

Novel SMD Component and Module Interconnection and Encapsulation Technique for Textile Substrates Using 3D Printed Polymer Materials.

Nowadays, a range of sensors and actuators can be realized directly in the structure of textile substrates using metal-plated yarns, metal-filament yarns, or functionalized yarns with nanomaterials, such as nanowires, nanoparticles, or carbon materials. However, the evaluation or control circuits still depend upon the use of semiconductor components or integrated circuits, which cannot be currently implemented directly into the textiles or substituted by functionalized yarns. This study is focused on a novel thermo-compression interconnection technique intended for the realization of the electrical interconnection of SMD components or modules with textile substrates and their encapsulation in one single production step using commonly widespread cost-effective devices, such as 3D printers and heat-press machines, intended for textile applications. The realized specimens are characterized by low resistance (median 21 mΩ), linear voltage-current characteristics, and fluid-resistant encapsulation. The contact area is comprehensively analyzed and compared with the theoretical Holm's model.

Prediction of Deposition Rate in Meniscus‐Confined Electrodeposition Based on Parameter Optimization Algorithm

Meniscus‐confined electrodeposition (MCED) is a potential approach to fabricate 3D metallic microstructures and can be used in microelectromechanical systems, optoelectronics, and flexible electrical interconnections. However, deposition efficiency and the quality of the microstructures obtained by this method on optimal parameters are identified by a large number of comparative experiments, resulting in high cost and inefficient practices. For this reason, herein, the fabrication process of metal microstructures by MCED simulation and optimizes parameters affecting deposition quality and rate is investigated. First, the finite‐element method is used to simulate the voltage and copper ion concentration identifies the target range. Then, the electrodeposition rate 1 × 10−7 m s−1 is set as the target value. The best applicable values of 0.29 V and 0.46 m are obtained after optimizing the voltage and copper ion concentration that affects the quality of deposited microstructures and rate of MCED based on the genetic algorithm (GA), cuckoo search (CS) algorithm, and support vector regression (SVR) algorithm. Finally, simulations and experiments are carried out according to the optimized parameters values. The results show that the maximum error of deposition rate is 7.9%. This study pioneers a new approach to achieving efficient and high‐quality deposition by MCED.

System-level reliability assessment of optical network on chip

Optical Network on Chip (ONoC) is now considered a promising alternative to traditional electrical interconnects. Meanwhile, several challenges such as temperature and process variations, aging, crosstalk noise, and insertion loss endanger the data transmission reliability of ONoCs. Many investigations have been made to evaluate the effect of these phenomena on ONoC’s reliability. However, system-level reliability assessment of ONoCs based on the failure rate of its essential elements has not been considered by the researchers yet. In this paper, we offer a reliability framework to calculate the reliability of micro-ring resonator, optical path, optical router, and optical topology architecture. Moreover, we developed a system-level simulator called Reliability Assessment of Photonic Network-on-Chips (RAP-NoC) to evaluate the reliability of different 2D and 3D optical routers and network-on-chip architectures in different data traffic patterns. The simulation results depict that Mesh topology improves the reliability parameter by about 5.2% compared to Torus in the same size and traffic patterns. Also, it can be concluded that Crux and DIPU routers are more reliable than the other 2D and 3D state-of-the-art optical routers.

Inkjet-printed electrical interconnects for high resolution integrated circuit diagnostics

As semiconductors continue to shrink in size and become more three-dimensional in shape, the size of defects that can induce a failure also reduces, pushing the need for better fault isolation. The resolving capability of microscopes used in failure analysis (FA) is frequently limited by how close the microscope can be brought to the circuit under test. Accessibility is often restricted by the presence of probe needles or wire bonds that are needed to power up the device during the measurement. Here, I describe a robust, rapid and cost-effective method to overcome the contacting bottleneck by re-routing the probe pads with a low-profile redistribution layer, realized by conductive inkjet printing. I demonstrate that the method enables analytical FA with high spatial resolution on a backside power delivery network structure in combination with the optical beam induced resistance change (OBIRCH) technique. Electrical and structural characterization of the printing process are also reported.

Investigation of CuAl IMCs Corrosion in Chloride Environment and its Prevention Strategy

Abstract In most current wire-bonding applications, electrical interconnection is accomplished by fine Cu wires bonded to Al bonding pads microfabricated on an IC chip and external contact pins of the PCB board. Corrosion-related failure defects between the Cu wire and Al bond pad have been an ongoing un-trackable reliability issue plaguing the IC packaging industry for the past ten years, despite approaching ppb levels. Most prior studies hypothesized that intermetallic compounds (IMCs) like Cu9Al4, and CuAl2 were responsible for the observed acute wire-bond lift-off corrosion defects. Further studies sought to quantify the rates of corrosion of these IMCs and explore the effects of mitigation efforts of adding Pd, relevant to Pd-coated Cu wire-bonding. However, utilizing a novel real-time corrosion screening approach, we previously established that peripheral bimetallic contact between Cu ball-bonds and Al bond pads also plays a substantial role in the aggressive Al pad corrosion, induced by chloride ion penetration, which often leads to device failure. In this work, we further explored the role of IMCs corrosion in wire-bond lift-off failure utilizing fundamental electrochemical studies to quantify rates of galvanic-induced corrosion of IMCs within the broader context of an interconnected stack of Al bond pad, Cu-Al IMCs and Cu bonding wire. We also explored the use of a corrosion inhibitor to suppress the galvanic corrosion currents of Al bond pad, and Al-rich IMCs when electrically connected to Cu wire or Cu-rich IMCs.

A Generalized Scalar Potential Integral Equation Formulation for the DC Analysis of Conductors

The electrostatic modeling of conductors is a fundamental challenge in various applications, including the prediction of parasitic effects in electrical interconnects, the design of biasing networks, and the modeling of biological, microelectromechanical, and sensing systems. The boundary element method (BEM) can be an effective simulation tool for these problems because it allows modeling three-dimensional objects with only a surface mesh. However, existing BEM formulations can be restrictive because they make assumptions specific to particular applications. For example, capacitance extraction formulations usually assume a constant electric scalar potential on the surface of each conductor and cannot be used to model a flowing current, nor to extract the resistance. When modeling steady currents, many existing techniques do not address mathematical challenges such as the null space associated with the operators representing the internal region of a conductor. We propose a more general BEM framework based on the electric scalar potential for modeling conductive objects in various scenarios in a unified manner. Restrictive application-specific assumptions are not made, and the aforementioned operator null space is handled in an intuitive and rigorous manner. Numerical examples drawn from diverse applications confirm the accuracy and generality of the proposed method.

Optimal Dispatching Method of Integrated Energy System of Electrothermal Interconnection Based on Energy Flow

Aiming at the problem that the total amount of coal consumption and the abandoned wind is too high in the actual operation of the current integrated energy system of electric heating and interconnection, this paper studies the design of the optimal dispatching method of the system from the angle of energy flow. The potential energy dissipation rate of the heat source, heat exchanger, heat pipe network, and other structures in the system is described in mathematical form, and a complete system energy flow model is constructed by combining them. On this basis, the heat load of system users is analyzed and predicted from the angle of energy flow. Finally, the system is divided into power and gas grid variables, optimized to realize distributed multi-objective optimal scheduling. By comparing the operation of the system before and after the optimal scheduling, it is found that the total coal consumption and the total abandoned wind during the system operation are reduced after the optimal scheduling, which proves that the optimal scheduling method has a very high practical application value.

Interfacial Capillary Spooling of Conductive Polyurethane-Silver Core-Sheath (PU@Ag) Microfibers for Highly Stretchable Interconnects.

Conductive fibers are core materials in textile electronics for the sustainable operation of devices under mechanical stimuli. Conventional polymer-metal core-sheath fibers were employed as stretchable electrical interconnects. However, their electrical conductivity is severely degraded by the rupture of metal sheaths at low strains. Because the core-sheath fibers are not intrinsically stretchable, designing a stretchable architecture of interconnects based on the fibers is essential. Herein, we introduce nonvolatile droplet-conductive microfiber arrays as stretchable interconnects by employing interfacial capillary spooling, motivated by the reversible spooling of capture threads in a spider web. Polyurethane (PU)-Ag core-sheath (PU@Ag) fibers were prepared by wet-spinning and thermal evaporation. When the fiber was placed on a silicone droplet, a capillary force was generated at their interface. The highly soft PU@Ag fibers were fully spooled within the droplet and reversibly uncoiled when a tensile force was applied. Without mechanical failures of the Ag sheaths, an excellent conductivity of 3.9 × 104 S cm-1 was retained at a strain of 1200% for 1000 spooling-uncoiling cycles. A light-emitting diode connected to a multiarray of droplet-PU@Ag fibers exhibited stable operation during spooling-uncoiling cycles.

Remarkable Conductive Anisotropy of Ag-Coated Glass Microbeads/UV Adhesive Composites Made by Electric Field Induced Alignment

We successfully prepared highly anisotropic conductive composites (ACCs) made of Ag-coated glass microbeads/UV adhesive via electric field-induced alignment, which was achieved using custom patterned microelectrode arrays. An optimized AC electric field (2 kV/cm, 1 kHz) with pole-plate spacing (50 μm) was utilized to effectively assemble the microbeads into chain arrays, which were precisely positioned on the microelectrode arrays to construct ordered conductive channels. In this case, tangling and cross-connection of the assembled microchains could be reduced, resulting in enhanced performance of the ACCs with high conductivity as well as excellent anisotropy. With a minor loading (3 wt %), the conductivity in the alignment direction could reach ∼24.9 S/m, which was the highest among the reported ACCs to the best of our knowledge, and it could also be 6 orders of magnitude higher than that within the plane. Besides, the samples exhibited high reliability in wire connections with low resistances. Due to these fascinating properties, the ACCs demonstrate promising applications for reliable electrical interconnects and integrated circuits.