Printed Circuit Research Articles

Nimble native oxides: Printing circuits from the skin of liquid metal

Nimble native oxides: Printing circuits from the skin of liquid metal

Ionic liquid based electroless silver plating bath for Printable circuit boards (PCBs) finishing

Immersion silver-plating technique is typically used for uniform coating on printed circuit boards (PCB) for finishing. Herein, we report an unconventional protocol for preparation of non-toxic immersion silver-plating solution/bath. The solution was prepared through electrolysis using ionic liquid (1, 3-disulfonic acid imidazolium hydrogen sulfate [Dsim] [HSO4]) as electrolyte, metallic silver (Ag) as anode and copper as cathode. As a result of electrolysis, IL-capped aqueous charged silver ion (Ag+) solution [colloidal Ag-IL adduct solution] is obtained. Presence of Ag+ in solution was verified by cyclic voltammetry (CV) experiments. Chemical reduction of Ag+ with Hydrazine Hydrate (NH2-NH2·H2O) yielded AgNPs. The AgNPs analyzed through dynamic light scattering (DLS) exhibiting 269.99 ± 14.2 nm size with Polydispersity Index (PDI) 0.126. The metallic copper strip immersed into the solution and a shiny silver plated surface obtained within 1–5 min at room temperature. Film thickness can be controlled by varying time of immersion. The corrosion rate was found to be 0.0012 mm/a by Tafel fitting. The solution is stable for the months without losing efficiency whereas the recovered IL used five times without significant loss in efficiency.

Hall effect in the MnBi2Te4 crystal using silicon nitride nanomembrane via contacts

Utilizing an interplay between band topology and intrinsic magnetism, the two-dimensional van der Waals (vdW) system MnBi2Te4 provides an ideal platform for realizing exotic quantum phenomena and offers great opportunities in the emerging field of antiferromagnetic spintronic technology. Yet, the fabrication of MnBi2Te4-based nanodevices is hindered by the high sensitivity of this material, which quickly degrades when exposed to air or to elevated temperatures. Here, we demonstrate an alternative route of fabricating vdW-MnBi2Te4-based electronic devices using the cryogenic dry transfer of a printable circuit embedded in an inorganic silicon nitride membrane. The electrical connections between the thin crystal and the top surface of the membrane are established through via contacts. Our magnetotransport study reveals that this innovative via contact approach enables exploring the MnBi2Te4-like sensitive 2D materials and engineering synthetic heterostructures as well as complex circuits based on the two-dimensional vdW systems.

2D High-Temperature Superconductor Integration in Contact Printed Circuit Boards.

Inherent properties of superconducting Bi2Sr2CaCu2O8+x films, such as the high superconducting transition temperature Tc, efficient Josephson coupling between neighboring CuO layers, and fast quasiparticle relaxation dynamics, make them a promising platform for advances in quantum computing and communication technologies. However, preserving two-dimensional superconductivity during device fabrication is an outstanding experimental challenge because of the fast degradation of the superconducting properties of two-dimensional flakes when they are exposed to moisture, organic solvents, and heat. Herein, to realize superconducting devices utilizing two-dimensional (2D) superconducting films, we develop a novel fabrication technique relying on the cryogenic dry transfer of printable circuits embedded into a silicon nitride membrane. This approach separates the circuit fabrication stage requiring chemically reactive substances and ionizing physical processes from the creation of the thin superconducting structures. Apart from providing electrical contacts in a single transfer step, the membrane encapsulates the surface of the crystal, shielding it from the environment. The fabricated atomically thin Bi2Sr2CaCu2O8+x-based devices show a high superconducting transition temperature of Tc ≃ 91 K close to that of the bulk crystal and demonstrate stable superconducting properties.

Intrinsically conductive and nano-scale reconfigurable liquid metal nano-capsules

Liquid metal (LM), particularly Gallium-based alloy, has emerged as an indispensable material for artificial skins, offering vast potential in wearable prophylactic medicine, AI-based human-machine interfaces, bodily-kinesthetic monitoring, etc. Nanosized LM has been adopted to facilitate its processability in various LM-elastomer interfaces, stretchable circuits, and dynamic self-healing devices. However, a naturally formed electrical-passive oxidation layer (Ga2O3) on LM nanoparticles would impede electron transportation, rendering the original LM nanoparticles nonconductive even when they are compacted together. Attempts, e.g., mechanical activation and chemical-assisted erosion, have been developed to remove this electrical barrier, but lead to other issues, including circuit short, weaken interfacial bonding, and unforeseen activation. Here, intrinsically conductive LM nano-capsules were proposed to address these issues. These nano-capsules are in situ encapsulated by platinum@redox graphene oxide (Pt/rGO) and exhibit an intrinsically high conductivity (up to 1.2 × 106 S m−1). The encapsulation process was assisted by oxidation layer thinning and particle-to-particle bridging through polyelectrolyte (PSS). As a result, the Pt/rGO tow-dimensional layer effectively can be encapsulated on LM nanoparticles via electrostatic interaction to enable conductivity of the shells of nano-capsules. And the highly compact and reconfigurable profile of the LM nano-capsules can be developed for highly conductive circuits. The LM nano-capsules maintain chemical and mechanical stability against external stimuli, including long-term exposure (up to 7 days in solvent and 30 days in air) and mechanical deformations (ΔR/R0 < 4% after 5000 stretching cycles under strain of 100%). And the LM capsule ink shows easy access to design printable circuits (∼70 μm) and fabricate electronic tattoos for robotic sensory skins and real-time health-monitoring technologies.

Interactive Aqueous Ink from Core‐Shell Liquid Metal and PEDOT:PSS

AbstractLiquid metals (LMs) and conjugated polymers are both critically important materials in modern technologies including soft robotics, printable circuits, and stretchable electronics. Although broadly applied, the joint use of LMs and conjugated polymers are rarely explored due to the notoriously interfacial challenges of the high surface tension of LMs and the unfavorable rigid backbones of conjugated polymer chains. This work successfully introduced conjugated polymers (poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate, (PEDOT:PSS)) into the system of liquid metals to provide a highly stable, aqueous, and electrically conductive ink (LM‐PEDOT:PSS inks, LMPInks) for flexible electronics. The PSS segments act as a strong ionic bridge to effectively stabilize core‐shell structure of the PEDOT and LMs in the homogenous ink. Different from previous insulated LM‐inks, LMPInk is aqueous and more importantly, electrically conductive without posttreatments due to the intrinsically conductive PEDOT:PSS. Interestingly, with low content of LM particles (&lt;2 wt%), the printed circuits inherit the valuable transparency of PEDOT:PSS (transmission &gt;92% in visible region), which has never been observed in LM‐based organic systems. Furthermore, such LMPInks show distinguished electrical robustness, which can automatically recover their initial electrical conductivity even after severe physical damage. With the above phenomenal advantages, various flexible circuits on different substrates are successfully provided.

Potential usage of E waste as tiles with latex coating

Electronic waste is defined as wasted electrical equipment used in electronics that are meant for reuse, rescale, salvage, recycling, or disposal. E-waste is a colloquial term for electronic items that have reached the end of their “useful life.” Common electronic items include computers, TVs, VCRs, stereos, copiers, and fax machines. Many of these items can be reused, repaired, or repurposed. The capacity to acquire and recycle minerals from e-waste reduces the need for them to be mined from the Earth. This conserves natural resources all across the planet. According to the United Nations, precious metal concentrations in electronic trash are 40 to 50 times richer than ore obtained from the soil. India generates over 50 million tonnes of e-waste every year. The biggest problem is to handle waste-printed circuit boards (WPCBs), which account for around 3–6% of total garbage. In this project we are going to make tiles by using PCB board (Printable Circuit Board) E waste and coated with latex. The main purpose of the project is to make alternative product to replacement of tiles.

A Simple and Cost-Effective Method for Producing Stable Surfactant-Coated EGaIn Liquid Metal Nanodroplets.

Liquid metals show unparalleled advantages in printable circuits, flexible wear, drug carriers, and electromagnetic shielding. However, the efficient and large-scale preparation of liquid metal nanodroplets (LM NDs) remains a significant challenge. Here, we propose a simple and efficient method for the large-scale preparation of stable eutectic gallium indium nanodroplets (EGaIn NDs). We compared different preparation methods and found that droplets with smaller particle sizes could quickly be produced using a shaking technique. The size of EGaIn NDs produced using this technique can reach 200 nm in 30 min and 100 nm in 240 min. Benefiting from the simple method, various surfactants can directly modify the surface of the EGaIn NDs to stabilize the prepared droplets. In addition, we discovered that shaking in an ice bath produced spherical nanodroplets, and after shaking for 30 min in a non-ice bath, rod-shaped gallium oxide hydroxide (GaOOH) appeared. Furthermore, the EGaIn NDs we produced have excellent stability—after storage at room temperature for 30 days, the particle size and morphology change little. The excellent stability of the produced EGaIn NDs provides a wider application of liquid metals in the fields of drug delivery, electromagnetic shielding, conductive inks, printed circuits, etc.

Facile synthesis of paper based graphene electrodes for point of care devices: A double stranded DNA (dsDNA) biosensor

The demand for high-quality graphene for electronic applications is increasing due to its high carrier mobility and electrical conductivity. In this connection, printing technology is a reliable method towards the fabrication of conductive, disposable graphene-based electrode for low-cost sensor application. Herein, we aimed to report the synthesis of high-quality graphene nanosheets obtained by electrochemical exfoliation of biomass-derived from corn cob. The conductive ink was prepared from this exfoliated graphene and was utilized for the preparation of paper-based graphene electrode towards double stranded DNA (dsDNA) sensor application. This paper, based graphene electrode opens the possibility of direct electrochemical analysis of analyte without any sample preparation. In this study, two irreversible oxide peaks were obtained from paper-based printed graphene electrode, corresponds to oxidation of guanine (G) and adenine (A) of dsDNA in the linear range of 0.2 pg mL−1 to 5 pg mL−1 with the detection limit of 0.68 pg mL−1 and the sensitivity of 0.00656 mA pg−1 cm−2. Further, a small-scale printable circuit is fabricated using this graphene shows good conductivity of 1.145x103(S/m).

Synaptic and Digital Switching in Diffusion Effect‐Assisted Oxides for All‐Inorganic Flexible Memristor

In this work, an all‐inorganic memristor based on In ion‐diffused Al2O3 (IAO) is realized by low temperature solution method. Compared to single layer devices, the electrical properties of IAO‐based memristor are highly improved. In this device, both of synaptic and digital switching can be observed by controlling the applied voltage. At a low applied voltage, the memristor exhibits synaptic switching behavior including gradual switching, learning process, forgetting process, and relearning process. If a higher voltage is applied, the switching behavior is changed to digital bipolar switching which could be also archived in bending condition. The switching mechanism is dominated by oxygen vacancies modulation on concentration and formation energy. This novel device can be expected to open a new road for hybrid and printable circuits including synaptic and digital flexible memristors.

Flexible and conductive polyurethane composites for electromagnetic shielding and printable circuit

With recent emergence of portable and wearable electronics, it is imperative to design a novel electromagnetic interference (EMI) shielding material which possesses flexibility, ultra-thinness and excellent EMI shielding effectiveness (SE) to prevent the adverse effect of electromagnetic radiation. Herein, we fabricate the ultrathin and flexible four corners needle zinc oxide whiskers/silver/waterborne polyurethane (T-ZnO/Ag/WPU) conductive films to realize different EMI shielding demand by tuning the nanofiller dispersion morphology. The T-ZnO/Ag/WPU composite film with uniform structure (prepared by blade coating method) shows excellent flexibility and EMI SE of over 42 dB at a thickness of only 0.02 mm. Highly reliable shielding ability is achieved with 92% EMI SE retention after 1000 folding cycle tests. The T-ZnO/Ag/WPU composite film with deposited layer structure (prepared by casting method) exhibits an ultrahigh EMI SE of over 87 dB at a thickness of 0.25 mm. At the same time, the T-ZnO/Ag/WPU composite shows great potential in printable circuit. The ultrathin and flexible T-ZnO/Ag/WPU composite films with excellent EMI SE are highly promising for applications in next-generation flexible electronics, especially the portable and wearable electronic devices.

Heuristics for Two-Dimensional Rectangular Guillotine Cutting Stock

Two-Dimensional Rectangular Guillotine Cutting Stock Problem (2DRGCSP) is one of the most significant problems in the manufacturing industries. A set of small rectangular size of paper, aluminum rolls, glasses, fiber glasses, or plastic are required to cut from a set of big size rectangular sheet of its raw materials. A guillotine cut is used, where the sheet is cut from one side to another side without changing the direction of the blade to produce the strips. Then each strip is cut again to produce the small rectangular size of panels that match with the required size, and the number of the panels must satisfy with the demand. This paper presents the heuristic techniques to solve the cutting problems. The heuristic techniques create the good cutting patterns such that the waste of the sheets is minimized and demands for each panel are satisfied. There are five proposed heuristics, developed to solve this problem. They are 2D simple heuristic cutting (2DSHC), 2D horizontal construction (2DHC), 2D vertical construction (2DVC), 2D horizontal improvement (2DHI), and 2D vertical improvement (2DVI). The testing instances are created from the real problems in the Printed Circuit Board (PCB) Company. The results are presented and compared with column generation (CG) method. The proposed heuristics provide good cutting patterns with a comparable waste to the column generation method. Moreover, the heuristics can produce solutions in a short computational time even in the large size instances, where the column generation method cannot find the solution. Therefore, these proposed heuristics techniques are applicable to solve the 2DRGCSP in the industry where the solutions from the exact algorithms cannot be found.

DEVELOPMENT OF A POWER MANAGEMENT CIRCUIT FOR MICROENERGY HARVESTERS

This work reports on the development a power management circuit (PMC) for micro energy harvesters. The circuit is design to regulate the power between three different power sources for the operation of a wireless sensor nodes (WSNs). The main components of the circuit are resistors (carbon film), capacitors (electrolytic), inductors (ferric bead, axial leaded), and a DC voltage regulators (TPS62100DRC-BRR). The layout of the circuit is patterned on a printed circuit board (PCB) using PCB fabrication technology. To the circuit three different types of sources (DC power source, rectified AC voltage and a solar energy harvester) are connected and the output regulated voltage provided by the PMC is measured and analyzed. At different input voltage levels (0.5 to 5.5 V) the circuit successfully regulated to almost a uniform output voltage (2.75 to 2.96 V). With the circuit using a DC power source and a solar (solar cell) energy harvester a super capacitor is charged to a voltage of 2.75 and 2.05 V in 180 s and 840 s respectively. Beyond 100 Ω load resistance the PMC regulated a constant output current of 180 mA. Moreover, beyond 100 Ω load resistance the power consumption of the circuit is almost steady for different input voltage levels. The average consumption of the developed PMC is about 70 mW.

Adapting the Chemical Reaction Optimization Algorithm to the Printed Circuit Board Drilling Problem

Chemical Reaction Optimization (CRO) is an optimization metaheuristic inspired by the nature of chemical reactions as a natural process of transforming the substances from unstable to stable states. Starting with some unstable molecules with excessive energy, a sequence of interactions takes the set to a state of minimum energy. Researchers reported successful application of the algorithm in solving some engineering problems, like the quadratic assignment problem, with superior performance when compared with other optimization algorithms. We adapted this optimization algorithm to the Printed Circuit Board Drilling Problem (PCBDP) towards reducing the drilling time and hence improving the PCB manufacturing throughput. Although the PCBDP can be viewed as instance of the popular Traveling Salesman Problem (TSP), it has some characteristics that would require special attention to the transactions that explore the solution landscape. Experimental test results using the standard CROToolBox are not promising for practically sized problems, while it could find optimal solutions for artificial problems and small benchmarks as a proof of concept.

Characterization of a vertically movable gate field effect transistor using a silicon-on-insulator wafer

The vertically movable gate field effect transistor (VMGFET) is a FET-based sensing element, whose gate moves in a vertical direction over the channel. A VMGFET gate covers the region between source and drain. A 1 μm thick air layer separates the gate and the substrate of the VMGFET. A novel fabrication process to form a VMGFET using a silicon-on-insulator (SOI) wafer provides minimal internal stress of the gate structure. The enhancement-type n-channel VMGFET is fabricated with the threshold voltage of 2.32 V in steady state. A non-inverting amplifier is designed and integrated on a printable circuit board (PCB) to characterize device sensitivity and mechanical properties. The VMGFET is mechanically coupled to a speaker membrane to apply mechanical vibration. The oscillated drain current of FET are monitored and sampled with NI LabVIEW. The frequency of the output signal correlates with that of the input stimulus. The resonance frequency of the fabricated VMGFET is measured to be 1.11 kHz. The device sensitivity linearly increases by 0.106 mV/g Hz in the range of 150 Hz and 1 kHz.

Performance of a-SiGe:H Thin-Film Solar Cells on High-Heat Dissipation Flexible Ceramic Printable Circuit Board

In this paper, a flexible ceramic printable circuit board (FCPCB) consisting aluminum (Al) metal layer and ceramic layer is used as a substrate for solar cell fabrication. A 3-layer graded bandgap hydrogenated amorphous silicon-germanium absorber and an etched Al-doped zinc oxide are applied to single-junction cell fabrication to increase the cell conversion efficiency up to 6.3%. For temperature rise test, the heat energy could easily move from Al through the ceramic layer to the air. Both high-thermal conduction and thermal dissipation lead to a low rise in substrate temperature after long illumination, and thus to a high maintenance in solar cell performance. The bending test indicates a 12.6% degradation in conversion efficiency of FCPCB cells after bending 5000 times. The FCPCB substrate with high flexibility and thermal stability demonstrates great potential of use in flexible thin-film solar cell applications.

Mobile Manipulation Platform Control

This paper presents a mobile manipulation platform control for the industrial manipulator Nokia PUMA (Programmable Universal Manipulation Arm). The main research steps were: designing the control system for the direct current motors, that provides motion of the manipulator‘s links and platform, then - thinking through and writing algorithms for a single board computer for providing data acquisition and impacts generation, and designing the printed circuit boards for motion control. The goal was to design an autonomous industrial manipulator with multitasking and abilities of spatial orientation and pattern recognition.

Printed silver circuits for FMCG packaging

Purpose – Printed flexible circuits that combined conventional silicon technology will enable the realisation of many value added products such as smart packaging for the fast moving consumer goods (FMCG) industry. This paper aims to describe an investigation into integrating silicon and printable circuits for the FMCG packaging industry and this would allow products with features such as brand protection, time temperature indicators, customer feedback and visual product enhancement. Responding to interest from the FMCG packaging industry, an investigation was carried out which investigated the printing conductive silver ink on common packaging substrates. Design/methodology/approach – Standard IC mounting patterns were screen printed using two conductive silver materials (one high silver content traditional paste and one lower silver content gel polymer) to four plastic and three paper substrates which represent common FMCG substrates (HDPE, BOPP, PET and three paper substrates). Materials were characterised in terms of material rheology whereas prints were characterised through electrical performance and printed film topology. Findings – There was a significant interaction between the substrate, silver ink formulation and the resultant line quality, line topology and conductivity. On paper substrates, the absorption of binder into the substrate resulted in denser silver packing and higher conductivity for the paste material. Higher conductivities were obtained on the substrates capable of withstanding higher curing temperatures. On the polymer substrates higher conductivity could be obtained by lower content silver materials due to the denser particle packing in the cured ink film as a result of its higher solvent/lower solids components. Research limitations/implications – Further work should examine the interactions for other printing processes commonly used in the FMCG industry such as rotogravure of flexography and should also examine nano particle materials. Further work should also address the mechanical adhesion of silicon logic on the substrates and bottlenecks in processing. Practical implications – The lower silver content gel material potentially provides material cost reduction by a factor of between 4 and 7 for the same conductivity. The gel material also has potential for more uniform performance across all substrate types. Typically 3.1 Ω/cm resistance values are achieved on all substrates for 300 micron lines. Originality/value – For those in the field of smart packaging the work has highlighted the interaction between silver materials and non PET/PEN substrates in flexible printed circuits. It has demonstrated the implications of rheology, substrate absorbency and materials processing temperature on circuit design. For those seeking printing process understanding it has provided further validation to support material transfer mechanisms in the screen printing process.

МоделюваннЯ керуючиХ пристроїВ длЯ сенсорниХ безпровідниХ мереЖ ZigBee

Розглянуто програмні засоби для моделювання керуючих пристроїв безпровідних мереж ZigBee на основі 8-бітних мікроконтролерів сімейства 8051. Запропоновано методику відлагодження основних режимів роботи мікроконтролера та периферійних пристроїв в програмному середовищі PROTEUS. Показано особливості використання цього програмного пакету в процесі проектування керуючого пристрою на основі мікроконтролера СС2530

Automated extraction of PCB components based on specularity using layered illumination

This paper investigates the methodologies for locating and identifying components on a printed circuit board (PCB) used for surface mount device inspection. It's the foundation of other inspections...