Good Electrical Connection Research Articles

Hierarchical heterostructures of MXene and mesoporous hollow carbon sphere for improved ion accessibility and rate performance

The development of electrode materials with a hierarchically porous structure and good electrical connection is key to improving the charging-discharging rate and energy density of supercapacitors. However, the restacking issue of two-dimensional nanomaterials, such as MXene, seriously hinders the diffusion of electrolyte ions. Different from the extensively used sacrificing template method, a hierarchical heterostructure of electrically conducting mesoporous hollow carbon spheres (MHCS) and MXene composite electrode is designed and achieved through simple vacuum filtration without further template removing procedures. This direct preparation strategy not only effectively improves the specific surface area of the electrode but also enhances the abundant surface pores and good conductivity of MHCS, improving the penetration of the electrolyte solution and shortening the ion transport path, leading to a pronounced improvement in specific capacitance and rate performance of the electrodes. Additionally, the influence of sheath thickness of MHCSs on ion transfer rate is deeply discussed. The introduction of carbon nanotubes (CNTs) further improves conductivity and stability while maintaining good flexibility. Consequently, the MXene/MHCS/CNT film delivers a high specific capacitance (395F g−1 at 2 mV s−1), outstanding rate performance (70.9 % at 1000 mV s−1), and excellent cycling stability (98.3 % capacity retention after 10,000 cycles). Furthermore, the assembled symmetric supercapacitor provides a maximum energy density of 14.48 Wh kg−1. This work provides a quick and effective approach for constructing high performance 3D MXene architectures for fast ion transfer electrodes.

Enabling focused ion beam sample preparation for application in reverse tip sample scanning probe microscopy

Focused ion beam (FIB) has become a powerful tool for transmission electron microscopy sample preparation in the nanoelectronics industry and has in recent years also shown its benefits for specific preparation steps in electrical scanning probe microscopy (SPM). Most recently, a novel SPM approach – so-called reverse tip sample (RTS) SPM – has been proposed in which the position of sample and tip are switched compared to standard SPM; in RTS SPM the sample is attached to the end of a cantilever beam. To achieve this configuration, the region of interest must first be extracted from a substrate and then needs to be reliably fixed to the cantilever by FIB. Therefore, we have explored and developed dedicated FIB preparation methods for RTS SPM in this work. Our established procedures ensure a strong mechanical and good electrical connection of the sample to the cantilever for both cross-section and top view sample preparation. Furthermore, we introduce an approach for mounting samples from a full wafer size workflow. This paper presents the developed FIB procedures and discusses the quality and stability of all mounted samples and their electrical evaluation in RTS SPM.

Weld-free mounting of lamellae for electrical biasing operando TEM

Recent advances in microelectromechanical systems (MEMS)-based substrates and sample holders for in situ transmission electron microscopy (TEM) are currently enabling exciting new opportunities for the nanoscale investigation of materials and devices. The ability to perform electrical testing while simultaneously capturing the wide spectrum of signals detectable in a TEM, including structural, chemical, and even electronic contrast, represents a significant milestone in the realm of nanoelectronics. In situ studies hold particular promise for the development of Metal-Insulator-Metal (MIM) devices for use in next-generation computing. However, achieving successful device operation in the TEM typically necessitates meticulous sample preparation involving focused ion beam (FIB) systems. Conducting contamination introduced during the FIB thinning process and subsequent attachment of the sample onto a MEMS-based chip remains a formidable challenge. This article delineates an improved FIB-based sample preparation methodology that results in good electrical connectivity and operational functionality across various MIM devices. To exemplify the efficacy of the sample preparation technique, we demonstrate preparation of a clean cross section extracted from a Au/Pt/BaSrTiO3/SrMoO3 tunable capacitor (varactor). The FIB-prepared TEM lamella mounted on a MEMS-based chip showed current levels in the tens of picoamperes range at 0.1 V. Furthermore, the electric response and current density of the TEM lamella device closely align with macro-scale devices. These samples exhibit comparable current densities to their macro-sized counterparts thus validating the sample preparation process and confirming device connectivity. The simultaneous operation and TEM characterization of electronic devices enabled by this process enables direct correlation between device structure and function, which could prove pivotal in the development of new MIM systems.

Effect of Sn Plating Thickness on Wettability, Solderability, and Electrical Connections of Electronic Lead Connectors for Surface Mount Technology Applications

The wettability of solder is important to achieve good solderability between the electronic component and printed circuit board (PCB). Tin (Sn) plating is widely used to promote the wettability of the solder on the substrates. However, an adequate amount of Sn plating thickness must be taken into consideration to acquire good wettability and solderability. Thus, this study investigates the Sn plating thickness of the electronic lead connector and their effect on the wettability and electrical connection. Two types of Sn plating thicknesses, ~3 μm, and 5 μm were applied on the electronic lead connector surface. It was found that the thin Sn plating thickness of ~3 μm has shown failure in electrical connections and lack of solder joint wettability and solderability properties. A thicker Sn plating thickness of 5 μm, has shown better wettability and solderability properties. In addition, the electrical connections also passed which implies that the thicker Sn plating thickness provides good solder joint establishment leading to good electrical connections. It is also observed that the better wettability of solder has been achieved for thicker Sn plating thickness. The finding from the field emission scanning electron microscope (FESEM) shows that the intermetallic compound (IMC) layer growth in the lead connector surface is regarded as abnormal for thin Sn plating thickness (~3 μm), in which the IMC layer was consumed and penetrating up to the surface of Sn-coating. This has led to poor solderability of the thin Sn plating with the solder to establish solder joint. The findings from this study have shed some light upon a better understanding of the importance of considering the adequate amount of Sn coating thickness to avoid IMC consumption at the Sn plating, better wettability properties, solderability, and solder joint quality for surface mount technology (SMT) especially for electronic lead connector applications.

Cross-linking chemistry enables robust conductive polymeric network for high-performance silicon microparticle anodes in lithium-ion batteries

Low-cost silicon microparticles (SiMPs) are more promising anode materials towards practical implementation due to their higher volumetric energy density and less side reactions than Si nanoparticles. However, SiMPs always suffer from extremely dramatic mechanical fracture caused by volume expansion during cycling, and hence a far inferior cycle stability to Si nanoparticles. Herein, a highly cross-linked 3D conductive polymeric network, consisting of amino-functionalized long single-wall carbon nanotubes (SCNT–NH2–L) and poly(acrylic acid)/sodium carboxymethyl cellulose, has been prepared via esterification and amidation reactions during electrode preparation process. Benefiting from limiting effect and stress-dissipation provided by the unique network, it can keep complete electrode structure and ensure good electrical connection between broken Si particles during cycling. Meanwhile, the newly formed ester groups in the network can greatly enhance the reaction kinetics of silicon for superior Li+ storage. As a result, the as-prepared SiMPs anode delivers an ultrahigh initial discharge capacity of 3861.4 mAh g−1 at 100 mA g−1 and a superior cycle stability with high capacity retention of 74.3% from 20th to 200th cycle at 2000 mA g−1. Our work provides a novel but simple stress-dissipation strategy to enable the stable operation of silicon microparticle in lithium-ion batteries.

Fabrication of 3D microstructures in glass by direct writing electrochemical discharge machining

ABSTRACT The formation of 3D copper-filled microstructures in glass using direct writing electrochemical discharge machining (ECDM) and electrodeposition techniques is presented. Single-row stainless steel tool electrodes having tip sizes of 150 µm were made by wire electrodischarge machining (W-EDM). Tool wear mechanism and the tip size correction of the worn-out tools were investigated. Significant tool wear was observed after 5 ECDM repetitions of the tool electrodes involving drilling and milling operations. Due to the high temperature generated in the ECDM process, there is significant erosion in the tool electrodes, and the tip heights of the electrodes became non-uniform. Thus, the single-row tool electrode became non-reusable in the ECDM process. Therefore, the electrochemical dissolution (ECD) method was used to correct the tip dimension and make the tool reusable for the ECDM process. After the ECD correction, the obtained tip size was close to the original size of 150 µm with <5% inter-tip size variation. Up to two-cycle of ECDM and ECD size correction was performed; thus, enhanced reusability of the single-row tool electrodes was demonstrated. The 3D structures were metallized using the copper electroplating method. DC measurement of the microstructures showed good electrical connectivity with an ohmic nature.

Facile and Rapid Electrochemical Conversion of Ni into Ni(OH)2 Thin Film as the Catalyst for Direct Growth of Carbon Nanotubes on Ni Foam for Supercapacitors

In this paper, a facile and rapid aqueous-based electrochemical technique was used for the phase conversion of Ni into Ni(OH)2 thin film. The Ni(OH)2 thin film was directly converted and coated onto the network surface of Ni foam (NF) via the self-hydroxylation process under alkaline conditions using a simple cyclic voltammetry (CV) strategy. The as-formed and coated Ni(OH)2 thin film on the NF was used as the catalyst layer for the direct growth of carbon nanotubes (CNTs). The self-converted Ni(OH)2 thin film is a good catalytic layer for the growth of CNTs due to the fact that the OH- of the Ni(OH)2 can be reduced to H2O to promote the growth of CNTs during the CVD process, and therefore enabling the dense and uniform CNTs growth on the NF substrate. This binder-free CNTs/NF electrode displayed outstanding behavior as an electric double-layer capacitor (EDLC) due to the large surface area of the CNTs, showing excellent specific capacitance values of 737.4 mF cm-2 in the three-electrode configuration and 319.1 mF cm-2 in the two-electrode configuration, at the current density of 1 mA cm-2 in a 6 M KOH electrolyte. The CNTs/NF electrode also displayed good cycling stability, with a capacitance retention of 96.41% after 10,000 cycles, and this the excellent cycling performance can be attributed to the stable structure of the direct growth of CNTs with a strong attachment to the NF current collector, ensuring a good mechanical and electrical connection between the NF collector and the CNTs.

Replaceable Bilayer Structure for Two-Dimensional Resistive Sensor Array

Two-dimensional resistive sensor arrays (2-D RSAs) have wide applications including intelligent robots, medical diagnosis, wearable devices, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">etc</i> . For fast replacing a damaged sensitive unit or changing the function of a sensitive unit which were difficult to realize in most sensor arrays, we proposed sensitive unit with replaceable bilayer structure (SU-RBS) for the 2-D RSA. In a SU-RBS, each two-end resistive sensing unit comprises a replaceable sensitive layer (RSL) and a fixed electrode layer (FEL). Every RSL is fitted on its FEL which is fixed on a substrate in shared row-column fashion. For fast removing and reinstalling the RSL, a hook Velcro and a loop Velcro are used with the hook Velcro on the RSL’s bottom surface and the loop Velcro on the FEL’s top surface. Two pairs of metal wire electrodes in spiral shape are used for good electrical connection between the RSL and its FEL. On the RSL, each metal pin of the two-end resistive sensor is coiled into a spiral pin electrode and fixed on the Velcro’s hook surface. On the FEL, two spiral wire electrodes with one for shared column electrode and the other for shared row electrode are fixed on the Velcro’s loop surface. For evaluating the performance of the sensor array based on the SU-RBS, a double-layer sensing glove was designed and its experiments were implemented. The experimental results show that the SU-RBS-based RSA of low cost and easy replaceability has good performance.

Enhancing the tensile properties of Sn-Zn-Ag lead-free solder alloy by loading MgO nanoparticles and irradiation

Lead-free composite solders has attracted more attention as they are required in the microelectronics industry to assure good electrical connections and the best mechanical response between integrated circuit devices and the substrate. The mechanical mixing technique was used to prepare the plain (Sn-5.3 wt% Zn-1 wt% Ag, SZA531) and composite solder (SZA531/0.5 wt% MgO), while MgO nanoparticles were synthesized by sol-gel technique. The aim to investigate the effects of loading 0.5 wt% MgO NPs and [Formula: see text]-irradiation doses (0–2.0 MGy) on the tensile properties of plain solder at different strain rates (ε•). The microstructural properties revealed that MgO was pure, crystalline, and had a nanoparticle-like morphology with an average crystallite size of 9.61 nm. Plain and composite solders contained β-Sn, Zn, and Ag, as well as some intermetallic compounds, Ag3Sn and AgZn. Loading MgO refined [Formula: see text]-Sn and Ag3Sn, while AgZn particles were partially dissolved. The thermal analysis reported that the melting point slightly increased from 206.1°C with SZA531 to 208.7°C when loaded which confirms the good solderability of composite solder. The tensile properties revealed that ultimate tensile strength and the tensile toughness increased with increasing ε•, dose of γ-rays, and MgO loading, while ductility decreased. The strain rate sensitivity index ( m) decrease with increasing the dose and MgO loading because of the decrease in the resistance to necking. These results were interpreted based on Orowan strengthening and dislocation strengthening.

Understanding the Effect of Pore Size on Electrochemical Capacitive Performance of MXene Foams.

Wearable electronics demand energy storage devices with high energy density and fast charging-discharging rates. Although various porous electrodes have been constructed, the effect of pore size on the capacitive performance of 2Dnanomaterials has been rarely studied. Herein, flexible MXene foams with significantly different pore structures are fabricated using varying diameter polystyrene (PS) spheres (80, 310, and 570nm), whichshows uniform pores and interconnected pores providing enough active sites and a good electrical connection for electron transfer. Noteworthy, when MXene flakes and templates (310nm) have a similar size, the foam delivers the highest gravimetric capacitance of 474± 12 F g-1 at 2mV s-1 than others. Additionally, the mass ratio between MXene and PS controls the packing density of foams influencing the inner resistance of foam electrodes. A carbon nanotube is introduced to further improve the electrical conductivity of foams to achieve a capacitance of 462± 8 F g-1 at 2mV s-1 and retains 205± 10 F g-1 at 1000mV s-1 , demonstrating promises in energy storage applications and providingan insightful guidance for designing 2D nanomaterials-based porous electrodes for supercapacitors.

Investigating electrochemical deposition of gold on commercial off-the-shelf 3-D printing materials towards developing sensing applications.

The COVID-19 pandemic highlighted the inaccessibility of quick and affordable clinical diagnostics. This led to increased interest in creating low-cost portable electrochemical (EC) devices for environmental monitoring and clinical diagnostics. One important perspective is to develop new fabrication methods for functional and low-cost electrode chips. Techniques, such as electron beam and photolithography, allow precise and high-resolution electrode fabrication; however, they are costly and can be time-consuming. More recently, fused deposition modeling three-dimensional (3-D) printing is being used as an alternative fabrication technique due to the low-cost of the printer and rapid prototyping capability. In this study, we explore enhancing the conductivity of 3-D printed working electrodes with EC gold deposition. Two commercial conductive filament brands were used and investigated to fabricate electrode chips. Furthermore, strategies to apply epoxy glue and conductive silver paint were investigated to control the electrode surface area and ensure good electrical connection. This device enables detection at drinking water concentration thresholds. The practical application of the fabricated electrodes is demonstrated by detecting Cu2+ using anodic stripping voltammetry.

Three-Dimensional Porous Network Electrodes with Cu(OH)2 Nanosheet/Ni3S2 Nanowire 2D/1D Heterostructures for Remarkably Cycle-Stable Supercapacitors.

Developing advanced electrode materials with highly improved charge and mass transfer is critical to obtain high specific capacities and long-term cycle life for energy storage. Herein, three-dimensionally (3D) porous network electrodes with Cu(OH)2 nanosheets/Ni3S2 nanowire 2D/1D heterostructures are rationally fabricated. Different from traditional surface deposition, the 1D/2D heterostructure network is obtained by in situ hydrothermal chemical etching of the surface layer of nickel foam (NF) ligaments. The Cu(OH)2/Ni3S2@NF electrode delivers a high specific capacity (1855 F g–1 at 2 mA cm–2) together with a remarkable stability. The capacity retention of the electrode is over 110% after 35,000 charge/discharge cycles at 20 mA cm–2. The improved performance is attributed to the enhanced electron transfer between 1D Ni3S2 and 2D Cu(OH)2, highly accessible sites of 3D network for electrolyte ions, and strong mechanical bonding and good electrical connection between Cu(OH)2/Ni3S2 active materials and the conductive NF. Especially, the unique 1D/2D heterostructure alleviates structural pulverization during the ion insertion/desertion process. A symmetric device applying the Cu(OH)2/Ni3S2@NF electrode exhibits a remarkable cycling stability with the capacitance retention maintaining over 98% after 30,000 cycles at 50 mA cm–2. Therefore, the outstanding performance promises the architectural 1D/2D heterostructure to offer potential applications in future electrochemical energy storage.

Ti3C2Tx MXenes reinforced PAA/CS hydrogels with self‐healing function as flexible supercapacitor electrodes

AbstractLightweight, thin, and stretchable flexible microelectronic devices have become a new challenge for researchers. To provide power for these conformable devices, it is necessary to design the energy storage device into a flexible and stretchable structure. In this paper, a two‐step method was used to prepare a dual‐physical cross‐linked polyacrylic acid/chitosan/Ti3C2Tx(PCT) conductive hydrogel flexible electrode. The three‐dimensional (3D) porous structure not only offers a good electrical connection, but also saves the use of binder and additional current collector, which helps to enhance the electrochemical properties of electrode. The unique two‐dimensional layered structure of Ti3C2Tx enables the hydrogel electrode to withstand considerable pressure deformation without breaking, and has excellent tensile properties. The flexible electrode exhibited an excellent tensile strength of 0.083 MPa if only introduced 0.31 wt% of Ti3C2Tx with the tensile strain of 158.63% and owned remarkable self‐healing properties after injury. Thereby, the hydrogel electrode renders a maximum capacitance of 291.8 mF g−1 at 0.5 mA/g and a good cycling stability with 64.24% capacitance retention after 2000 charge–discharge cycles. This provides a research and development strategy for binder‐free, non‐toxic, and mini‐size flexible energy storage devices.

Interconnecting layers of different crystalline silicon bottom cells in monolithic perovskite/silicon tandem solar cells

In the past five years, power conversion efficiency (PCE) of monolithic perovskite/silicon tandem solar cells is improved from 13.7% to 29.15%, demonstrating a massive growth. The electrical and optical properties of interconnecting layers (ICLs) play one of crucial roles in determining the performance of perovskite/crystalline silicon (c-Si) tandems. And the employment of ICLs is directly related with front passivation of bottom c-Si cells. Here, we reviewed the respective development progresses of ICLs for different c-Si bottom cells in monolithic perovskite/c-Si tandem solar cells. Then we present key strategies to realize a good electrical connection and light management. Finally, optimized ICLs were designed to enhance PCE of tandems based on the balance between optical and electrical aspects for different c-Si bottom cells, which will shed light on ICLs of perovskite/silicon tandems.

Assembling flower-on-sheet CoP–NiCoP nanohybrids as efficient self-supported electrocatalysts for hydrogen evolution reaction in both acidic and alkaline media

Self-supported electrocatalysts are directly employed as electrodes for water splitting. Herein, we report an effective strategy to develop flower-on-sheet structured nanohybrids, where CoP nanoflowers are epitaxially grown along the edges of Ni-Co-P nanosheets (namely NiCoP) on carbon cloth (m-CoP–NiCoP/CC), thus obtained as efficient self-supported electrodes for the hydrogen evolution reaction (HER) in both acidic and alkaline media. This unique nanostructure endows NiCoP nanosheets with maximal exposed surface area, along with increased active sites brought by CoP nanoflowers. Moreover, due to good electrical connection between CoP nanoflowers and NiCoP, and between conductive NiCoP and carbon cloth, electrons can easily transfer from active sites to the conductive substrates. Therefore, the m-CoP–NiCoP/CC exhibits superior catalytic activity and stability for HER in both acidic and alkaline media. The as-prepared electrocatalyst requires overpotentials of only 75.0–81.5 mV to deliver a benchmark current density of 10 mA cm−2 in acidic and alkaline media, respectively, which are superior to most of the previously reported metal phosphides-based electrocatalysts. Hence, this work can provide a design for developing highly active electrocatalysts for water splitting. The self-supported CoP-NiCoP nanohybrids were prepared as efficient and durable electrocatalysts for hydrogen evolution reaction in both acidic and alkaline media, where CoP nanoflowers are epitaxially grown along the edges of NiCoP nanosheets.

Direct growth of flower-shaped CoS1.097 nanoflakes on flexible carbon cloth: An ultrastable cycle durability anode for reversible sodium storage

ABSTRACT It is highly attractive for constructing CoSx-based electrode architectures in sodium ion batteries (SIBs). Herein, a three-dimensional flower-shaped CoS1.097 nanoflakes grown on carbon cloth is developed and examined as flexible anode configuration for SIBs, showing a large discharge capacity of 835.7 mAh g−1 at 0.1 A g−1 and ultrastable lifetime of 1000 cycles at 5 A g−1. The superior sodium storage capability can be attributed to the unique flexible electrode with connected three-dimensional hierarchical porous structure, which makes for ensuring good electrical connection, sustaining the structural integrity of electrode and facilitating fast ion diffusion kinetics upon cycling.

Direct Growth of Flower-Shaped Cos1.097 Nanoflakes on Flexible Carbon Cloth: An Ultrastable Cycle Durability Anode for Reversible Sodium Storage

It is highly attractive for constructing CoSx-based electrode architectures in sodium ion batteries (SIBs). For the first time, a three-dimensional flower-shaped CoS1.097 nanoflakes grown on carbon cloth is developed and examined as flexible anode configuration for SIBs, showing a large discharge capacity of 835.7 mAh g-1 at 0.1 A g-1 and ultrastable lifetime of 1000 cycles at 5 A g-1. The superior sodium storage capability can be attributed to the unique flexible electrode with connected three-dimensional hierarchical porous structure, which makes for ensuring good electrical connection, sustaining the structural integrity of electrode and facilitating fast ion diffusion kinetics upon cycling

P‐6.8: Study of Mass Transfer for Micro‐LED Manufacturing

Micro‐LED is superior to LCD and OLED in terms of power consumption, light efficiency, contrast, response time, reliability, color gamut, lifetime, resolution and viewing angle, it is regarded as the most promising display technology in next generation. However, there are still many technical bottlenecks that hinder the development of Micro‐LED display. One of the most important technical issues is mass transfer. Mass transfer is a technology aim to transferring millions or even tens of millions of Micro‐LED pixels which grown on sapphire substrates to the glass substrates required for display devices quickly and correctly and providing good electrical and mechanical connections between the Micro‐LED pixels and the drive circuits. There have been many companies that have been working to solve this problem and have come up with solutions from different technical aspects. In this paper, we will review several different technologies, classify them from the technical type, evaluate the maturity and achievability of the technology, and analyze the application fields of different technologies.

Towards electrically tunable nanofiltration membranes: polyaniline-coated polyvinylidene fluoride membranes with tunable permeation properties

Conductive polyaniline (PANI)-coated polyvinylidene fluoride (PVDF) composite nanofiltration (NF) membranes were synthesized by an in situ chemical oxidative interfacial polymerization (solution and diffusion cell polymerization) to produce pressure filtration membranes with tunable separation selectivity through applying an external electrical potential. The diffusion cell polymerization technique was found to be superior with ability to coat a greater thin layer PANI film (120% mass increase) than solution polymerization (13% mass increase) after 48 h of reaction time. Furthermore, the conductivity of the PANI membrane synthesized by diffusion cell polymerization was far higher than that of the solution polymerization membrane, which was up to 6.711 S/cm compared to 7.61 × 10–2 S/cm, respectively, showing that a continuous film with good electrical connectivity has been formed. Meanwhile, a modified dynamic contact angle test showed that the membranes were electrically tunable with about 30–40% decrement on the contact angle values after an external electrical potential was applied. Moreover, the membranes with a complete surface PANI coverage (around 30–80 mass percentages) confirmed to have their permeability for neutral species (polyethylene glycols) electrically tuned under cross-flow conditions. Overall, this work demonstrated that the diffusion cell polymerization method produced membranes that have the potential to be applied as electrically tunable NF membranes.

Differential charging analysis of Nb-TiO2 thin films on SiO2 substrates

Chemical vapor deposition (CVD) prepared TiO2 films, with and without Nb doping, were subjected to enhanced differential charging using an external bias and analyzed by x-ray photoelectron spectroscopy (XPS). It was found that charge barriers exist between the Ti and Si/O components in the undoped sample indicating an incomplete chemical interaction. After Nb doping, these differences are eliminated showing good electrical connection between all sample components. These results illustrate how differential charging can be used to identify electrical and chemical properties of doped films beyond traditional XPS measurements. They also provide information that is relevant to the understanding of passivation in the composite samples. The authors show the importance of additional charge compensation as well as correct mounting when employing the technique.