Conductive Patterns Research Articles

Investigating the impact of Nano Cu at different weight percentages on the electrical conductivity of aluminum wire

This research focuses on effects of three different nano cu on Aluminum wire to study the electrical conductivity pattern in those composite wires. The need for enhancing the electrical conductivity of materials has led to innovative approaches such as the incorporation of nanoscience into metal matrices. In this study, the effects of nano copper (Cu) at three different weight percentages (1%, 2%, and 3%) on the electrical conductivity of aluminum wire were studied carefully. Nano cu had an average of 150 nanometer nm length with 99.8 purity. Understanding these effects is crucial for advancing the development of high-performance conductive materials for various applications, including electronics and power transmission.

Impact of adjacent thoracic structures in negative left atrial remodelling in atrial fibrillation

Abstract Background Previous work has suggested that compression from external structures can promote negative atrial remodelling in atrial fibrillation (AF) [1]. This is mechanistically plausible, with many recognised risk factors in developing AF (age, hypertension, obesity, obstructive sleep apnoea, etc.) related through activation of the autonomic nervous system with an associated increase in atrial pressure and chronic elevation in wall stress [2,3]. Such negative remodelling contributes to the existence of arrhythmogenic atrial substrate [4]. This is highly significant when we consider catheter ablation of extrapulmonary vein targets. Purpose This study aims to investigate the relationship between abnormal conduction patterns indicative of potential AF drivers and their proximity to structures adjacent to the left atrium (LA). Methods Eight patients with paroxysmal or persistent AF, scheduled for an elective catheter ablation procedure using a charge density mapping (CDM) system [5] underwent pre-procedural cardiac MRI. 3D surface mesh reconstructions of individuals’ LA and adjacent structures (ascending aorta [AoA], descending aorta [AoD], and spine) were produced from 2D MRI slices using a proprietary graphical interface tool developed in MATLAB (Figure 1A & B) [6]. MRI derived LA geometries were registered with their CDM counterparts by the Iterative Closest Point algorithm (Figure 1C); this enabled integration of MRI LA geometries into the CDM system. Subsequently, non-contact intrachamber voltage measurements from individuals’ procedures were used to derive cardiac activation directly onto MRI LA geometries. Abnormal conduction patterns representing possible AF drivers (focal firing, rotational propagation, and pivoting propagation) [5] were quantified as occurrences per second at each vertex of MRI LA geometries (Figure 1D). These conduction patterns could then be visualised and assessed in the context of adjacent structures (Figure 1E), with the Euclidean distance between each vertex of the MRI LA geometries and the closest point to their adjacent structures being calculated. Results Mean age was 65±9 years; 4 patients (50%) were male; AF was paroxysmal in 3 (37%) and persistent in 5 (63%); median time since AF diagnosis was 1 (1-3.8) years; ablation type was de novo in 5 (63%) and retreatment in 3 (38%). Frequencies of pivoting and rotational propagation were notably higher in regions of the LA closer to the AoA, and lower near the AoD and spine (Figure 2A & B). Conversely, focal firing showed a less prominent trend, being more frequent in LA regions nearer the AoD and distant from the AoA (Figure 2C). Conclusions Compression from the ascending aorta may promote anterior LA remodelling in AF, leading to increased pivoting and rotational AF drivers. Clinically, this suggests a potential target for ablation therapy with an anterior seatbelt line connecting the right superior pulmonary vein to the mitral annulus.

Detecting epicardial connection through intercaval bundle using intra-atrial activation sequence during right pulmonary vein pacing

Abstract Background An epicardial connection (EC) through the intercaval bundle (EC-ICB) between the right pulmonary vein (RPV) and the right atrium (RA) is one of the reasons for the need of carina ablation for PV isolation. Purpose We evaluated the intra-atrial activation sequence during RPV pacing after failure of ipsilateral RPV isolation and sought to identify specific conduction patterns in the presence of the EC-ICB. Methods This study included 223 consecutive patients undergoing initial catheter ablation of atrial fibrillation. If the RPV was not isolated by circumferential ablation or reconnected during the waiting period, an exit map during mid RPV carina pacing was created. If the earliest site of the exit map was the RA, the patient was classified into the EC-ICB group. During the exit map, intra-atrial activation sequence and RPV-HRA time were evaluated. Results First-pass isolation of the RPV was not obtained in 36 patients (16.1%), and 22 patients (9.9%) showing reconnection. Among them, 12 patients were classified into the EC-ICB group and 28 patients into the Non-EC-ICB group after excluding multiple ablation lesion sets or incomplete mapping. Intra-atrial activation sequence showed different patterns between the two groups. RPV-HRA time was significantly shorter in the EC-ICB group compared to the Non-EC-ICB group (69.2 ± 15.2 ms v.s. 148.6 ± 51.2 ms. P<0.001), and RPV-HRA time<89.0ms was highly predictive for existence of the EC-ICB (sensitivity 91.7 %, specificity 89.3 %). Conclusions The EC-ICB can be effectively detected by intra-atrial sequencing during RPV pacing and RPV-HRA time<89.0ms was highly predictive.

Vector Field Heterogeneity (VFH) as a novel quantitative marker of electrical disarray in Arrhythmogenic CardioMyopathy (ACM) with ventricular tachycardia

Abstract Background ACM is a hereditary condition characterized by fibrofatty infiltration and replacement of cardiac myocytes predominantly presenting with ventricular arrhythmias (VA). Cardiac imaging allows for detailed structural phenotyping of scar patterns in ACM. Yet, there is a lack of tools to objectively quantify the electrical substrate alterations that may enable a more precise identification of critical sites that predispose to VA. Purpose To quantify locally disorganized cardiac electrical propagation wavefronts using the Vector Field Heterogeneity (VFH) metric from high-density multi-electrodes in patients with ACM with VT and compare to healthy controls. Methods High density epicardial substrate maps acquired with a 16-pole grid catheter during SR or RV pacing in patients with ACM with VA, who underwent clinically indicated catheter ablation, were retrospectively reviewed. Patients with structurally normal heart and idiopathic VA with epicardial ablation were analysed as a control group. Unipolar contact mapping data was exported & processed offline. From the 4×4 electrode array EGMs, vector maps of the directions of electrical propagation for recorded sites were computed. The VFH was then computed as a quantitative measure of local heterogeneity of propagation, with higher VFH expected to correlate with sites of (micro)structural tissue alterations. VFH was compared between ACM and control patients as well as at sites of normal, border zone & scar based on omnipolar voltage in ACM patients (>1.5mV, 0.5mV–1.5mV, <0.5mV, respectively). Results 10 patients with ACM (70% male, aged 52 ±18 years, ARVC 70%, biventricular 30%, RVEF 40.7±4.7%, LVEF 66±12%) and 2 patients with structurally normal heart (female, 38 & 61 years) were included. Epicardial maps had an average of 9258 ±5412 EGM points. Median VFH was statistically significantly higher in the ACM cohort compared to control for global maps (0.33±0.33 vs 0.13±0.22, p<0.001) and at sites with voltage >1.5mV (i.e. greater disorganization in ACM, p<0.001). In ACM, assessment of VFH according to omnipolar voltage sites (as a surrogate of scar) showed a quantifiable statistically significant increase in electrical disorganized propagation at sites of lower voltage (<0.5mV, median VFH 0.53±0.36) compared to borderzone (0.5-1.5mV, VFH 0.29±0.41) and normal voltage (>1.5mV, VFH 0.15±0.26), p <0.001 respectively. Conclusion Heterogenous electrical propagation as quantified by VFH is significantly increased in patients with ACM at sites of scar, but importantly also in areas of normal voltages when compared to non-ACM controls, possibly indicating microstructural alterations that are missed in traditional assessments of the arrhythmogenic substrate. Identifying and quantifying disorganized conduction patterns by VFH is a promising new mapping approach that could allow improved substrate characterization. Its diagnostic value to guide ablation therapy is currently being validated.VFH Metric ACM and ControlVFH Map Examples

The occurrence of atrioventricular nodal reentrant tachycardia requires not only the electrophysiological substrate but also the electro-anatomical characteristics in the triangle of Koch

Abstract Background Some patients do not develop atrioventricular nodal reentrant tachycardia (AVNRT) clinically despite having the electrophysiological substrate for AVNRT; however, the cause remains unclear. Recently, the conduction to the slow pathway has been reported to be visualized using high-density mapping in the triangle of Koch (ToK) during sinus rhythm. Purpose To investigate whether the conduction to the slow pathway is associated with the occurrence of AVNRT. Methods We studied 83 patients (55 males, 67 ± 13 years, 10 with typical AVNRT, 66 atrial fibrillation; AF, 5 atrioventricular reentrant tachycardia; AVRT, and 2 Atrial Flitter) who received electrophysiological test and high-density mapping in the ToK during sinus rhythm. The conduction pattern to the slow pathway, rotating around the end (pivot point: PP) of the functional block line (FBL), was evaluated using the Advisor HD Grid mapping catheter. Results 10 out of 10 AVNRT (100%), 17 of 66 AF (26%), and 1 of 4 AVRT showed PP and FBL (p<0.0001). 21 out of 21 (10 AVNRT and 11 AF) with the jump-up phenomenon in atrioventricular conduction indicated PP and FBL (100%), meanwhile 7 of 62 without jump-up phenomenon showed PP and FBL (11%) (p<0.0001). Among patients (10 AVNRT and 9 AF) who had the electrophysiological substrate for AVNRT (jump-up phenomenon and retrograde ventriculoarterial conduction), patients with AVNRT had a longer distance from PP to the tricuspid annulus; TA (16.9mm vs, 13.4mm, p=0.0116) than patients with non-AVNRT. There were no differences in the length of FBI, distance and conduction time from His to PP, distance and conduction time from PP to CS ostial, and the area size of ToK. All AVNRT patients underwent linear ablation from PP to TA and showed loss of atrial potential in the region between PP, TA, and His, AVNRT was no longer provoked, and in 8 out of 10 patients, a jump-up phenomenon disappeared. Conclusion Patients with AVNRT showed a functional block line and a longer distance from the pivot point to the tricuspid annulus. The occurrence of AVNRT requires not only the electrophysiological substrate but also the electro-anatomical characteristics, especially in the triangle of Koch.

Electroless Copper Patterning on TiO2-Functionalized Mica for Flexible Electronics

The formation of conductive copper patterns on mica holds promise for developing cost-effective flexible electronics and sensing devices, though it is challenging due to the low adhesion of mica’s atomically flat surface. Herein, we present a wet-chemical method for copper patterning on flexible mica substrates via electroless copper deposition (Cu-ELD). The process involves pre-functionalizing 50 µm thick muscovite mica with a titanium dioxide (TiO2) layer, via a sol–gel dip-coating method with a titanium acetylacetonate-based sol. Photolithography is employed to selectively activate the TiO2-coated mica substrates for Cu-ELD, utilizing in situ photodeposited silver (Ag) nanoclusters as a catalyst. Copper is subsequently plated using a formaldehyde-based Cu-ELD bath, with the duration of deposition primarily determining the thickness and electrical properties of the copper layer. Conductive Cu layers with thicknesses in the 70–130 nm range were formed within 1–2 min of deposition, exhibiting an inverse relationship between plating time and sheet resistance, which ranged from 600 to 300 mΩ/sq. The electrochemical thickening of these layers to 1 μm further reduced the sheet resistance to 27 mΩ/sq. Finally, the potential of Cu-ELD patterning on TiO2-functionalized mica for creating functional sensing devices was demonstrated by fabricating a functional resistance temperature detector (RTD) on the titania surface.

Copper Paste Printed Paper‐Based Dual‐Band Antenna for Wearable Wireless Electronics

AbstractWearable wireless electronics is becoming a significant research area because of the unique features of this technology. Within this field printed antennas are the key electrical component accomplishing the signal transmission and energy harvesting tasks and at the same these antennas need to be lightweight, environmentally friendly, safe to wear, and easy to conform. Currently, the majority of available paper‐based antennas are designed for RFID, sensing, UWB, WLAN, and medical applications, with just a few being utilized in wearable applications, particularly for wireless body area network (WBAN). Furthermore, few studies have been conducted on the usage of printable copper conductive materials and low‐temperature plasma technique for the fabrication of such antennas. This study demonstrates the realization of a dual‐band paper‐based wearable antenna by screen‐printing of a plasma‐sintered conductive copper paste. The copper paste, composed of 51 wt% solid particles, can easily produce desired conductive patterns on photo paper after printing and a subsequent plasma sintering, with a good adhesion. The antenna designed on photopaper operates in the frequency bands of 1.73–2.55 GHz and 7.66–8.89 GHz. Free‐space simulation and measurement results reveal that the antenna exhibits stable radiation performance in the targeted WBAN (2.4–2.4835 GHz) and X uplink (7.9–8.4 GHz) frequency bands, together with low profile, excellent conformality and acceptable SAR values on the body and no electronic waste formed after disposal, making it a competitive candidate for usage in wearable wireless electronics.

The Impact of Stress Distribution on The Electrical Performance of Different Silver Stretchable Conductive Ink Pattern Using FEA Simulation

Stretchable conductive ink has been widely investigated to be used in the fabrication of stretchable electrical devices. Experimentation methods to test the mechanical and electrical behaviours of the stretchable conductive ink composite are commonly applied; however, not much of the computational approach has been scrutinized to validate the results further. This paper employs the finite element analysis method to investigate the relationship between the stress and strain distribution of the stretchable conductive ink with the highest strain obtained. This research validates the past experimentation works of different patterns of stretchable conductive ink for its stretchability and electrical performance. The maximum Von Mises stress (VMS) and maximum principal strain of the stretchable conductive ink played a significant role in determining its electrical performance, rather than the localisation of high stress and strain at specific locations within the stretchable conductive ink pattern. Zigzag pattern exhibited the lowest maximum stress and strain concentration at 57.826 MPa and 4.05% while straight pattern suffered the highest respective values at 118.143 MPa and 10.39%. The lower maximum Von-Mises stress and principal strain contributed to a better stretchability which is indicated by a higher strain rate prior to electrical conductivity.

Bubble Printing of Liquid Metal Colloidal Particles for Conductive Patterns.

Bubble printing is a patterning method in which particles are accumulated by the convection of bubbles generated by laser focusing. It is attracting attention as a method that enables the high-speed, high-precision patterning of various micro/nanoparticles. Although the bubble printing method is used for metallic particles and organic particles, most reports have focused on the patterning of solid particles and not on the patterning of liquid particles. In this study, liquid metal wiring patterns were fabricated using a bubble printing method in which eutectic gallium‒indium alloy (EGaIn) colloidal particles (≈diameter 0.7 µm) were fixed on a glass substrate by generating microbubbles through heat generation by focusing a femtosecond laser beam on the EGaIn colloidal particles. The wiring was then made conductive by replacing gallium oxide, which served as a resistance layer on the surface of the EGaIn colloidal particles, with silver via galvanic replacement. Fine continuous lines of liquid metal colloids with a line width of 3.4 µm were drawn by reducing the laser power. Liquid metal wiring with a conductivity of ≈1.5 × 105 S/m was formed on a glass substrate. It was confirmed that the conductivity remained consistent even when the glass substrate was bent to a curvature of 0.02 m-1.

Laser Sintering by Spot and Linear Optics for Inkjet-Printed Thin-Film Conductive Silver Patterns with the Focus on Ink-Sets and Process Parameters

The implementation of the laser sintering for inkjet-printed nanoparticles and metal organic decomposition (MOD) inks on a flexible polymeric film has been analyzed in detail. A novel approach by implementing, next to a commonly 3.2 mm diameter spot laser optic, a line laser optic with a laser beam area of 2 mm × 80 mm, demonstrates the high potential of selective laser sintering to proceed towards a fast and efficient sintering methodology in printed electronics. In this work, a multiplicity of laser parameters, primary the laser speed and the laser power, have been altered systematically to identify an optimal process window for each ink and to convert the dried and non-conductive patterns into conductive and functional silver structures. For each ink, as well as for the two laser optics, a suitable laser parameter set has been found, where a conductivity without any damage to the substrate or silver layer could be achieved. In doing so, the margin of the laser speed for both optics is ranging in between 50 mm/s and 100 mm/s, which is compatible with common inkjet printing speeds and facilitates an in-line laser sintering approach. Considering the laser power, the typical parameter range for the spot laser lays in between 10 W and 50 W, whereas for the line optics the full laser power of 200 W had to be applied. One of the nanoparticle silver inks exhibits, especially for the line laser optic, a conductivity of up to 2.22 × 107 S‧m−1, corresponding to 36% of bulk silver within a few seconds of sintering duration. Both laser sintering approaches together present a remarkable facility to use the laser either as a digital tool for sintering of defined areas by means of a spot beam or to efficiently sinter larger areas by means of a line beam. With this, the utilization of a laser sintering methodology was successfully validated as a promising approach for converting a variety of inkjet-printed silver patterns on a flexible polymeric substrate into functionalized conductive silver layers for` applications in the field of printed electronics.

Liquid metal-enhanced composite conductive ink with improved electrical stability and durability for flexible electronics

For flexible electronics, conductive ink is a critical material with diverse applications. However, conventional inks, like those based on nano-silver, are expensive and result in printed patterns with limited conductivity stability. To address these limitations and enhance overall electrical performance, stability, and durability, this study developed a novel composite conductive ink incorporating liquid metal and silver microparticles. We fabricated conductive patterns and extensively investigated the sintering process, focusing on how liquid metal content and sintering techniques affect the resulting patterns' electrical performance and stability. Our findings reveal that incorporating liquid metal introduces a slight trade-off in the initial conductivity. However, subsequent thermal and hot-press sintering treatments significantly improve conductivity, with hot-press sintering leading to the most pronounced enhancement. Furthermore, the addition of liquid metal substantially bolsters the electrical stability of the patterns. Notably, conductive patterns fabricated using a 1:1 mass ratio of the ink exhibit ∆R/R0 values of only 1.72 and 0.432 after 5000 bending cycles, following thermal and hot-press sintering, respectively. This highlights the significant improvement in electrical stability and durability achieved by incorporating liquid metal into the conductive ink.

Patterns of spatiotemporal variations in the hydrochemistry and controlling factors of bedrock aquifers in the northern region of the Linhuan mining area

Systematically studying the hydrochemical evolution of bedrock groundwater in mining areas during mining process is crucial for effective groundwater resource management and coal mine production. The spatiotemporal characteristics and hydrochemical evolution patterns of the Permian fractured sandstone aquifer (PA) and the Carboniferous Taiyuan Formation limestone aquifer (CTA), both of which are directly associated with coal mining in the northern Linhuan mining area, China, were investigated using multivariate statistical analyses, hydrochemical graphical methods, ion ratio analysis, and a conceptual model. 72 groundwater samples, collected before and after mining, were classified into four groups by hierarchical cluster analysis (HCA). Principal component analysis (PCA) and ion ratio analysis indicated that water-rock interactions involve mineral dissolution (carbonates, gypsum, dolomite, silicates), cation exchange, and common ion effects. Hydrochemical evolution is influenced by bedrock paleotopography, aquifer hydraulic conductivity, and mining drainage. Paletopographic differences significantly influence water-rock interactions and spatial variability in hydrochemistry, with ion concentrations in groundwater increasing as paleotopographic elevation decreases. The pattern of hydraulic conductivity reflects the control exerted by variations in aquifer characteristics on mineral dissolution, leading to minor changes in hydrochemical characteristics. Mining activities disrupt the aquifer's reducing environment, resulting in a significant increase in groundwater SO42− concentration. These findings provide insights and a solid theoretical foundation for studying the hydrochemical variations patterns of groundwater and these control mechanisms in the hidden coal fields of North China.

A numerical study on electrical conductivity in hybrid composites—Quantitative analysis of morphology variations in percolating networks

Hybrid composites comprising conducting nanowires (NWs) and insulating particulate fillers exhibit varying trends in their electrical conductivity based on the conditions of the constituent fillers. This study presents a quantitative model that comprehensively describes these changes, encompassing both increasing and decreasing trends. The model is formulated as an equation with two parameters quantifying the excluded volume effect and the NW bending effect, which are considered the primary factors determining NW network morphology in the composites. The influence of the parameters on the electrical conductivity of hybrid composites is analyzed with respect to the size and content of the constituent fillers using Monte Carlo-based simulations and statistical regression techniques. Numerical investigations reveal that distinct conductivity patterns under various particulate filler dimensions result from the interplay of these effects. The proposed model, validated through 2-D and 3-D simulations, effectively captures these complex interactions across diverse configurations of the constituent fillers.

Thermophysical Properties of (Y1-xErx)TaO4 Ceramics

A series of (Y1-xErx)TaO4 ceramics (x=0/6, 1/6, 2/6, 3/6, 4/6, 5/6, 6/6) were prepared using powders synthesized by the reverse co-precipitation technique. Investigations were conducted into the phase compositions, microstructure, and thermophysical characteristics. In contrast to yttria-stabilized zirconia (YSZ) ceramics, (Y1-xErx)TaO4 ceramics demonstrate reduced thermal conductivity and Young's modulus, along with greater coefficient of thermal expansions (CTEs). The impact of Er and Y elements on separation interferes with the parabolic relationship between thermal conduction and the composition of (Y1-xErx)TaO4 ceramics, modifying their thermal diffusion and conductivity patterns. Furthermore, the performance of (Y1-xErx)TaO4 ceramics was optimized by adjusting the ratio of Er/Y, from which (Y1-xErx)TaO4 ceramics exhibited lower thermal conductivity (1.38∼1.72 W·m-1·K-1 @ 800 °C), higher CTEs (9.24×10-6∼10.9×10-6 K-1 @ 1000 °C) and more excellent mechanical properties comparable to YSZ. Herein, (Y1-xErx)TaO4 ceramics show great potential for thermal barrier coating applications.

Profile improvement of blade coated circuits by the capillary force originating from the hydrophobic sidewalls

Abstract Restricting the diffusion of conductive inks plays a key role in printed electronics application. Micro-channels with different sidewall surface energies, which can be approximated as a capillary, are fabricated to restrict the blade-coated ink diffusion using both of the gravitational effect and the capillary force. The coffee ring effect of aqueous silver ink is inhibited by the capillary force when the hydrophobic sidewalls distance is no more than 50 μm in this paper. As a result, the conductive lines with improved cross-sectional profiles are obtained by this method, with the resistances about 1E8 times lower than the samples with hydrophilic sidewalls. The capillary force was also found to lose its effect when the width is larger enough, which needs surfactant addition to improve the silver film property. I-V curves and resistances of the original aqueous ink and the ink improved by traditional methods are compared, which confirms that the profile improvement by the hydrophobic sidewall can be used with other ink improving methods cooperatively. These studies open up the possibility of improving the printed conductive patterns by this method as an auxiliary tool used together with the traditional methods reported before.

Electroplating nickel patterns onto polyol-mediated reduced graphene oxide printed textile surfaces

This report explores advancements in multi-step printing/electroplating technique for creating conductive patterns on flexible substrates, which serve as potential structures in wearable electronic devices. The study introduces a novel procedure that employs a sequential process involving polyol screen printing and electroplating, enabling the development of conductive nickel-coated patterns with a conductivity value of about 1123 S/cm on textiles. A significant innovation in this study is the use of a graphene oxide/ethylene glycol (GO/EG) ink, which can be converted into reduced graphene oxide (rGO) through in-situ polyol treatment on the surface of PET fabrics. The effectiveness of this treatment is evidenced by various analytical and microscopic techniques, which confirm the successful printing of conductive rGO patterns onto PET fabric at 220 ˚C. The printed rGO patterns on the fabric surface are then subjected to electroplating as a target substrate and cathode for varying durations, ranging from 5 to 30 minutes. The study thoroughly examines the influence of electroplating time on the microstructures and electrical conductivity of the resulting patterns, with nickel deposition reaching up to 50.8 mg/cm².

Complementary split ring resonator-inspired multi-HCN for implementation of an efficiency-enhanced inverse class-F2,3 PA

This article introduces a conceptual framework for enhancing the efficiency of an inverse class-F2,3 (F2,3−1) power amplifier (PA) through the incorporation of an innovative metamaterial-based multi-harmonic control network (multi-HCN). In the recommended approach, the multi-HCN comprises two resonant cells inspired by square-shaped complementary split ring resonator (CSRR), which are configured to suppress unwanted harmonics and to obtain the desired waveforms. The primary focus is to showcase how CSRRs can be effectively employed to form a shunt resonator through the etching of the conductive pattern of the proposed multi-HCN. Apart their harmonic tunability, CSRRs offer various noteworthy attributes such as impressive wave restoration capabilities and the capacity to address spatial limitations. To assess the efficacy of the proposed methodology, a class-F2,3−1 PA is devised and constructed utilizing a commercially available 10 W GaN HEMT device. The presented class F2,3−1 PA yields a commendable drain efficiency (DE) ranging from 50.3 % to 84 % and achieves an output power within the range of 38 dBm to 41.2 dBm across the bandwidth of 3.3 GHz to 3.7 GHz. These significant performance metrics serve as compelling evidence, validating the effectiveness of the proposed approach. Furthermore, this achievement establishes the design as a promising path for creating high-performance, affordable PA suitable for emerging communication systems.

Silver-Organic Complex in Photosensitive Silver Pastes for Enhanced Resolution and Aspect Ratio.

Traditional screen printing is an easy approach commonly used for conductive pattern fabrication of electronics but lacks high resolution. Photolithography offers better resolution but is complex. Photosensitive silver pastes (PSP) combine the benefits of both but suffer from undercut issues, causing uneven etching, decreased interfacial adhesion, and thus poor resolutions. In this study, we explore the use of molecular precursors (i.e., silver oxalate) to replace metallic silver particles and enhance the depth of light penetration. Our findings demonstrate a successful solution to the undercut issue, achieving an undercut index of 1.0, indicating an undercut-free scenario and enabling higher resolutions in line and pattern formation. Additionally, our research confirms the feasibility of multilayer stacking of photosensitive pastes, achieving unprecedented aspect ratios in line patterns. By replacing 25% of micrometer silver powder with silver oxalate (PSP-25), we achieved optimal line widths as fine as 10 μm. The three-layer stack of PSP-25 reached a substantial aspect ratio with a height of 29.4 μm and an optimal fringe pattern resolution of 10 μm line width with a 15 μm aisle width. Utilization of silver oxalate was observed to slightly expand the line width, likely due to light scattering by the fine silver nanoparticles (∼40 nm) formed during the photodecomposition of silver oxalate.

Qualification Methodology for the Double Side Printed Substrate for Hybrid Microcircuits Application

Hybrid Microcircuits (HMCs) are always preferred over discrete versions due to small size, less weight, better performance and high reliability for space applications. Double side printed substrates realized using Thick film screen printing and Printed Through Hole (PTH) processes are being used in HMCs in order to achieve further miniaturization. This article details the newly developed innovative Thick film process technology involving drilling of holes and filling the through hole with gold conductive paste to connect the front and rear side of conductor patterns on an alumina substrate. The biggest challenge in the realization of double side printed substrates is creating multiple via holes and filling them with conductor paste. In addition, the limited ability to achieve substrate integration and uniformity pose additional challenges that require optimization of process parameters. A comprehensive test plan created to qualify this innovative method in terms of quality and reliability suitable for the aerospace industry is also presented.

Room temperature compressed air-stable conductive copper films for flexible electronics

The state-of-the-art technology of fabricating printed copper electronics is focussed largely on thermal sintering restricting transition towards heat sensitive flexible substrates. Herein we report a pioneering technology which eliminates the need for conventional sintering. Biopolymer-stabilised copper particles are prepared such that they can be compressed at room temperature to generate air-stable films with very low resistivities (2.05 – 2.33 × 10−8 Ω m at 20 °C). A linear positive correlation of resistivity with temperature verifies excellent metallic character and electron microscopy confirms the formation of films with low porosity (< 4.6%). An aqueous ink formulation is used to fabricate conductive patterns on filter paper, first using a fountain/dip pen and then printing to deposit more defined patterns (R < 2 Ω). The remarkable conductivity and stability of the films, coupled with the sustainability of the approach could precipitate a paradigm-shift in the use of copper inks for printable electronics.