Printed Wiring Boards Research Articles

Sustainable Upcycling of Spent Electric Vehicle Anodes into Solution-Processable Graphene Nanomaterials.

A major transition to electric vehicles (EVs) is underway globally, as countries target reductions in greenhouse gas emissions from the transport sector. As this rapid growth continues, significant challenges remain around how to sustainably manage the accompanying large volumes of waste from end-of-life lithium-ion batteries that contain valuable rare earth and critical materials. Here, we show that high-shear exfoliation in aqueous surfactants can upcycle spent graphite anodes recovered from an EV into few-layer graphene dispersions. For the same hydrodynamic conditions, we report a process yield that is 37.5% higher when using spent graphite anodes as the precursor material over high-purity graphite flakes. When the surfactant concentration is increased, the average atomic layer number reduces in a similar way to that of high-purity precursors. We find that the electrical conductance of few-layer graphene produced using the graphite flake precursor is superior and identify the limitations when using aqueous surfactant solutions as the exfoliation medium for spent graphite anode material. Using these nontoxic solution-processable nanomaterial dispersions, functional paper-based electronic circuit boards were fabricated, illustrating the potential for end-to-end, environmentally sustainable upcycling of spent EV anodes into new technologies.

Developing a highly responsive miniaturized security device based on a printed copper ammine energetic composite

This work presents a triggerable ultimate security device (USD) capable of physically destroying a memory chip that contains classified data within a few milliseconds upon the detection of intrusion. The USD is designed as an add-on module that can be positioned onto any electronic chip, IC circuit, or memory card without requiring any specialized chip design, substrate type or encapsulation solution. Its operation is simply based on the exothermic reaction of a solid-state printed energetic composite that physically disintegrates the sensible component in less than 1 ms. The solid-state energetic composite consists of a mixture of Al/CuO nanothermite with a copper ammine complex densely printed onto the chip that is meant to be destroyed. This energetic layer can be ignited through resistive heating or capacitance discharge in less than 50 µs. The paper details the fabrication and assembly of a test USD device and demonstrates that 400 mg of energetic composite can be used to irreversibly destroy one silicon chip (~120 mm 3 ) in less than 10 ms. The outcome of this work also shows that the reaction time and efficiency are highly dependent on the reactive material loading, i.e., the mass of nanothermites deposited into the device and memory card. • A novel ultimate security device concept is designed and developed. • The actuation is based on the reaction of a confined safe copper ammine energetics placed on the circuitry to be destroyed. • The pressure burst can be easily tuned by modifying the energetic composite solid loading. • A fast response is demonstrated. • The concept and technology hold potential for commercial scale production.

Superhydrophobic coating to mitigate metal corrosion with electrically insulative and thermally conductive properties

• A superhydrophobic coating was developed for electronic circuit boards. • Surface modified silica and polystyrene nanoparticles were used. • Electrochemical methods and the salt spray method proved the corrosion inhibition. • High thermal conductivity and electrical insulating properties were incorporated. • The coating can be used for substrates that need multifunctional properties. A superhydrophobic coating with hydrophobic silica nanoparticles (SiO 2 ), polystyrene nanoparticles (PS), aluminium trihydrate (ATH), and room temperature vulcanized silicone rubber (RTV SiR) was developed. The nanoparticles and the nanostructure of the coating were investigated using Scanning Electron Microscopy (SEM). The anti-corrosion ability was studied using 100% pure iron plates. The coating was found to have high resistance against corrosion based on electrochemical analysis and the salt-spray test in addition to high electrical insulation and thermal conductivity.

Development of Active-Ester Type Epoxy Resin Curing Agents for the Printed Wiring Boards of High-Speed Communication Devices

高速通信機器のプリント配線板用エポキシ材料の開発において低誘電率化，低誘電正接化を，硬化剤側から開発した。1991年に発表された活性エステル型エポキシ樹脂硬化剤の基本技術を発展させ，エレクトロニクス実装材料に対応できる新規の多官能オリゴマー型の活性エステル型エポキシ樹脂硬化剤の開発に成功した。一般的なフェノールノボラック硬化系と比較して，高いガラス転移温度を維持したまま，大幅な低誘電率，低誘電正接化を実現した。中心部に位置するジシクロペンタジエン骨格の剛直性と小さなモル分極率と大きなモル体積，末端封止成分のナフタレン骨格の剛直性や配向性が相まって，耐熱性を維持したまま，優れた低誘電率および誘電正接を示すと考察した。

Ultrathin WS2 nanobowls-based hybrid aerogels for selective trapping of precious metals from electronic wastes and elimination of organic dyes

Recycling precious metals from electronic wastes, minerals, waste catalysts, industrial wastewater and other wastes are of great significance to the construction of a sustainable industry framework, but it is still challenging. Herein, we for the first time proposed the design and preparation of two three-dimensional (3D) WS2 nanobowls hybrid aerogels (GA@WS2 Nbs and WS2 Nbs/GA) for the recovery of precious metal ions and highly efficient removal of organic dyes. The construction of tungsten disulfide nanobowls (WS2 Nbs) was optimized in morphology in consideration of the precursor concentration and reaction time. The prepared WS2 Nbs/GA was shown to rapidly capture Au(III) from printed wiring board (PWB) containing various interferents. The calculated capture capability of 1265.8 mg g−1 for Au(III) was obtained. It surprisingly involved that the deposition of nano gold (Au0) on the WS2 Nbs/GA was due to not only the selective chemistry of WS2 Nbs/GA but also its reduction interaction. Furthermore, the WS2 Nbs/GA exhibited remarkable efficiencies (99 %) in the removal of methylene blue. The unique properties gave the hybrid aerogels gifted ability in capturing Au(III) from electronic wastes and minerals. It provided a blueprint for the next generation green platform for precious metals and water treatment.

Recovery of Metals from Electronic Waste-Printed Circuit Boards by Ionic Liquids, DESs and Organophosphorous-Based Acid Extraction.

The extraction of metals from waste printed circuit boards (WPCBs) with ionic liquids (ILs), Deep Eutectic Solvents (DESs) and organophosphorous-based acid (Cyanex 272) has been presented. The study was undertaken to assess the effectiveness of the application of the new leaching liquids, and the new method of extraction of metals from the leachate and the solid phase with or without the leaching process. Solvent extraction from the liquid leachate phase has been studied in detail with popular ILs, such as tetraoctylphosphonium bromide, {[P8,8,8,8][Br] and tributyltetradecylphosphonium chloride, [P4,4,4,14][Cl] using Aqueous Biphasic Systems (ABS) method. Trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, [P6,6,6,14][Cyanex272], ([P6,6,6,14][BTMPP]), trihexyltetradecylphosphonium thiocyanate, [P6,6,6,14][SCN], methyltrioctylammonium chloride (Aliquat 336), as well as bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) were also used in the extraction of metals from the leachate. Two DESs (1) {choline chloride + lactic acid, 1:2} and (2) {choline chloride + malonic acid, 1:1} were used in the extraction of metals from the solid phase. The extraction behavior of metals with DESs was compared with that performed with three new bi-functional ILs: didecyldimethylammonium salicylate, [N10,10,1,1][Sal], didecyldimethylammonium bis(2-ethylhexyl) phosphate, [N10,10,1,1][D2EHPA], and didecyldimethylammonium bis(2,4,4-trimethylpentyl) phosphinate, [N10,10,1,1][Cyanex272]. The [P6,6,6,14][Cyanex272]/toluene and (Cyanex 272 + diethyl phosphite ester) mixtures exhibited a high extraction efficiency of about 50–90% for different metal ions from the leachate. High extraction efficiency of about 90–100 wt% with the ABS method using the mixture {[P8,8,8,8][Br], or [P4,4,4,14][Cl] + NaCl + H2O2 + post-leaching liquid phase} was obtained. The DES 2 revealed the efficiency of copper extraction, ECu = 15.8 wt% and silver, EAg = 20.1 wt% at pH = 5 from the solid phase after the thermal pre-treatment and acid leaching. The solid phase extraction efficiency after thermal pre-treatment only was (ECu = 9.6 wt% and EAg = 14.2 wt%). The use of new bi-functional ILs did not improve the efficiency of the extraction of metal ions from the solid phase. Process factors such as solvent concentration, extraction additives, stripping and leaching methods, temperature, pH and liquid/solid as well as organic/water ratios were under control. For all the systems, the selectivity and distribution ratios were described. The proposed extraction processes can represent alternative paths in new technologies for recovering metals from electronic secondary waste.

Fundamental Points of Power Distribution Network Design on Printed Wiring Board —Target Impedance and PI Validation—

Fundamental Points of Power Distribution Network Design on Printed Wiring Board —Target Impedance and PI Validation—

Design of Transmission Line in Printed Wiring Board —Way of Thinking about Characteristic Impedance, Reflection and Delay—

Design of Transmission Line in Printed Wiring Board —Way of Thinking about Characteristic Impedance, Reflection and Delay—

Ultra-Low-Loss and Broadband All-Silicon Dielectric Waveguides for WR-1 Band (0.75–1.1 THz) Modules

This study presents ultra-low-loss and broadband all-silicon dielectric waveguides for the WR-1 band (0.75–1.1 THz). The waveguides are built in high-resistivity silicon (10 kΩ-cm) and integrated with supportive frames fabricated from the same silicon wafer in a single etch process to achieve a compact design. We pursued low-loss, broadband, substrateless, unclad and effective medium waveguides. Smaller propagation losses of 0.3 dB/cm and 0.1 dB/cm were achieved for the unclad and effective medium waveguides, respectively. The 3 dB bandwidth was not encountered in the frequency range of interest and was as broad as 350 GHz. An unclad waveguide was employed to devise a Y-junction to demonstrate its practical applications in terahertz imaging. An integrated circuit card was successfully scanned. In addition, we developed unclad waveguide, effective medium waveguide, and Y-junction modules. The modules incorporated an input/output interface compatible with a standard WR-1 flange (254 μm × 127 μm). Unlike the conventional hollow waveguide modules, the unclad waveguide and effective medium waveguide modules reported total loss improvements of 6 dB and 8 dB, respectively, across the operation band. Our results provided a systematic way of achieving low-loss, compact, and versatile modules in the WR-1 band based on all-dielectric-waveguide platforms.

Development of Subsurface Magnetic Field Imaging System for Visualizing Electric Current Distribution inside Electronic Components and Storage Batteries

Recently, miniaturization and three-dimensional integration for improving the performance of electric devices have been accelerated, and smaller storage batteries with higher energy density and shrinked electric components have been more required. Therefore, failure analysis technologies targeted for these cutting-edged devices should be developed for increasing production yields and reducing product accidents. In mass production processes, pre-shipment inspections are performed on the core parts of electronic devices. In the case of electronic parts, energization check is adopted, and in the case of storage batteries, voltage drop, that is called to be an aging test, is checked. However, many cases have been reported in which products, that have passed the inspection, cause accidents. One of the typical causes of failures related about electronic components is internal electric-short caused by foreign matters mixed into the insulation or whiskers accidentally generated from the electrodes and wiring. Similarly, storage batteries also accidentally have internal short circuits due to foreign matter contaminations and dendrite formation at the electrodes. The internal short-circuited points of electronic components and storage batteries are identified by X-ray imaging method. However, it is difficult to acquire the contrast due to the lack of the dynamic range required for visualization of short-circuited parts because the wirings and insulation areas between electrodes have been significantly miniaturized. In addition, short circuits between wirings on the surface of electronic circuit boards have been visualized by thermography, although it is difficult to apply electronic components with multi-layered electrodes.Then we have focused on the relationship between the electric current distribution inside the devices and the magnetic field generated from it and spread toward outside, we have succeeded in deriving the analysis solution of the inverse problem for the first time. Combining this novel theory and a highly-sensitive magnetic field detection based on quantum effect, we have developed a subsurface electric current imaging system capable of detecting electric short-circuited points in the deep region. In this study, we discuss about the details of the theory about the analytical solution of the inverse problem and the visualization system, and show some results of failure analysis for actual electronic components and storage batteries.[1] Yuki Mima, Noriaki Oyabu, Takeshi Inao, Noriaki Kimura, Kenjiro Kimura, “Failure analysis of electric circuit board by high resolution magnetic field microscopy” Proceedings of IEEE CPMT Symposium Japan, pp.257-260, 2013.[2] Kenjiro Kimura, Yuki Mima, Noriaki Kimura, “Local electric current reconstruction theory for nondestructive inspection inside battery cell using magnetic field measurement”, Subsurface Imaging Science & Technology, 1, 1, pp.1-16, 2017.[3] Shogo Suzuki, Hideaki Okada, Kai Yabumoto, Seiju Matsuda, Yuki Mima, Noriaki Kimura, and Kenjiro Kimura, “Non-destructive visualization of short circuits in lithium-ion batteries by a magnetic field imaging system”, Japanese Journal of Applied Physics, Vol 60, No 5, pp.056502-1-4, 2021.

Analytical study of isothermal blade coating process using Rabinowitsch fluid model

Blade coating process is widely applied in the industry for its practical applications in photographic films, paint industries, and magnetic storage devices. Also for manufacturing newspaper, metal coating, electronic circuit boards, and textile fibers. The blade coating process passes a fluid into the gap between the moving substrate and blade. This study uses the Rabinowitsch model which represents the Newtonian, shear thickening, and shear thinning effects by changing a non-linear parameter. Lubrication theory is used to simplify the dimensionless governing expressions. Then perturbation technique is used up to second order to solve the resultant system and validated by the numerical shooting technique. The graphs and tables present how the non-linear parameter affects the dimensionless velocity, pressure profile, coating thickness, and blade load. The non-linear model parameter proves to be the controlling parameter for the coating thickness, blade load, and pressure distribution, helping in determining the coating efficiency and improving the substrate life. This paper provides the theoretical framework for engineers to be applied in many industrial applications. In future, further validation of results can be done through experiments.

Integral Plugged Blind via in Printed Wiring Boards

Adoption of fine pitch and high lead count area array components in high-reliability applications such as military and space electronics demands high-density interconnect (HDI) features in multilayer printed wiring boards (PWBs). Usage of cap-plated fine vias that are plugged with dielectric material is one of the approaches to meet the circuit density requirements. In this article, a novel method called “integral plugged blind via” without secondary processing steps, such as curing and planarization, is described to realize HDI multilayer PWBs. In this method, through vias are epoxy plugged during the lamination of inner layer circuits in vacuum-assisted hydraulic press cycle. Plugged blind vias are formed as an integral part of the fabrication process. It is observed that there is no excess ooze out of resin material from the blind vias in the laminated substrate and blind vias are found to have a negligible dimple and no voids. This is attributed to the gasket effect due to the elastomeric property of specialty release films, which conform (follow) to the contour of plated through vias during the vacuum lamination cycle. Plugged blind vias are subjected to critical thermomechanical stress to evaluate interconnection integrity. It is found that there is negligible change in the resistance of vias and resin plugged vias are free from defects such as barrel crack or knee crack of plated through hole (PTH) or delamination in the cured plugged material. Robustness of these resin-filled blind vias is attributed to anchored plated barrel with the additional support provided by plugged material, which restricts the thermomechanical deformation of plated copper.

Experimental studies of the electronic board cooling system

Objective. The purpose of the study is to illuminate the obtained experimental research data, measurement technique, as well as the design of a la-laboratory bench for full-scale tests of thermoelectric system (TES) for uneven cooling of electronic boards.Method. The article describes the experimental set-up and measurement procedure of laboratory thermoelectric system for electronic circuit boards cooling. The experimental stand is made on the basis of the measuring equipment of the laboratory of semiconductor thermoelectric devices and devices of Daghestan State Technical University.Result. We obtained plots of time dependences of temperature changes in thermoelectric system checkpoints at different thermoelectric battery (TEB) supply currents. Determined were the temperature dependences of the thermoelectric elements of the electronic board simulator at their non-uniform cooling on the parameters of FEB and working substance as well as the time variation of the temperature of the shell of the vessel with the working agent.Conclusion. As a result of full-scale tests of the device it was found that the use of a cooling system reduces the temperature of heat-generating elements to acceptable values. In particular, the temperature of heat sources decreases to 345 K and 344 K (from 428 K and 396 K) if the total heat-generating power of the electronic board is 120 W. At the same time, the temperature background created by the heat-generating elements in the nearby areas of the electronic board simulator also decreases. The discrepancy between the results of calculations carried out beforehand and the experiment was estimated to be 8%.

A Low-Current and Multi-Channel Chemiresistor Array Sensor Device.

This paper describes the design of a low-current, multichannel, handheld electronic device integrated with nanostructured chemiresistor sensor arrays. A key design feature of the electronic circuit board is its low excitation current for achieving optimal performance with the arrays. The electronics can rapidly acquire the resistances for different sensors, not only spanning several orders of magnitude, but also as high as several hundreds of megaohms. The device tested is designed using a chemiresistor array with nanostructured sensing films prepared by molecularly-mediated assemblies of gold nanoparticles for detection. The low-current, wide-range, and auto-locking capabilities, along with the effective coupling with the nanostructured chemiresistor arrays, meet the desired performances of a low excitation current and low power consumption, and also address the potential instability of the sensors in a complex sensing environment. The results are promising for potential applications of the device as a portable sensor for the point-of-need monitoring of air quality and as a biosensor for point-of-care human breath screening for disease biomarkers.

A Brief on Water Pump Level Adjustment & Monitoring System Using Arduino Uno

Abstract: Arduino is an ASCII text file programmable circuit card that will be programmed to sense and manage objects within the physical world. By responding to sensors and inputs, the Arduino is ready to act with an outsized array of outputs equivalent to LEDs, motors, and displays. The ESP8266 is capable of either hosting a degree application or offloading all LAN networking functions from another application processor. A pump is a tool that moves fluids (liquids or gases) by mechanical action. Pumps operate via several energy sources, alongside manual operation, electricity, engines, or wind power. An integrated development setting (IDE) is also a coding system application that provides comprehensive facilities to pc programmers for software package development. Some IDEs, appreciate NetBeans and Eclipse, contain the obligatory compiler, interpreter, or both.

Enhanced adhesion of copper plating to polyether ether ketone based on active oxygen species generated under ultraviolet irradiation

Polyether ether ketone (PEEK) is a substrate for metal plating to overcome insulation defects and satisfy the increased demands of mechanically robust electronic circuit boards. However, pristine PEEK is hydrophobic; hence, the adhesion between the metal film and PEEK substrate is poor. Therefore, the PEEK surface should be modified to improve hydrophobicity. We have proposed the active oxygen (AOS) treatment under ultraviolet (UV) light as an alternative to a conventional plasma treatment method. Characteristics of the PEEK surfaces obtained by these methods are compared. We explore the effects of reactive‐oxygen and UV light exposure time on the PEEK surface modification. The contact angle of water drop on PEEK after the AOS treatment is lower than that of untreated PEEK. Furthermore, COO groups are observed on the PEEK surface after the treatment. Although plasma treatment has the effect of roughening the surface, it is desirable not to roughen the surface for use in electronic circuit boards. Moreover, we have reported the adhesion strength between PEEK and copper plating without surface roughening.

Modelling and Evaluating Electromagnetic Field Exposure in the Multiple-Source Scenario of Using IoT HF RFID Readers.

The aim of this study was to evaluate Specific Absorption Rate (SAR) and induced electric field (Ein) values in the model of a body of a person present near multiple HF RFID readers of a passive proximity integrated circuit card (PICC) working in an IoT application in a public transport vehicle, in order to test the hypothesis that even the simultaneous use of modelled readers does not cause electromagnetic field (EMF) exposure exceeding relevant limits provided for the evaluation of exposure of the general public. SAR and Ein values were evaluated under various exposure scenarios, designed to mimic EMF exposure under realistic conditions of HF RFID readers used on a public bus and covering various reader locations and the presence of a person using a PICC and a bystander. The results obtained from numerical modelling showed that the absorption of EMF emitted continuously by HF RFID readers (located 10 cm away from a body) in the human body may have a significant influence on humans when the PICC reading ranges are longer than 15–23 cm (depending on the class of PICC) for a single reader and when multiple sources of exposure are used in a public transport vehicle—even at reading ranges 15% shorter (13–20 cm).

Experimental Study and CFD Modelling for Thermal Cooling Improvement of Electronic Components Using Graphene Nanosheets Coated

Electronic circuit boards’ heat dissipation capability directly impacts their service life since the heat dissipation efficiency of components directly impacts the board’s life. This work focused on the problem of the high surface temperature of the electronic components at the control unit stage of a cement production line. Three dimensional CFD model has been developed to simulate all components in this circuit board. A thermographic camera has been used to measure the surface temperatures of the components on the circuit board. Consistency was very good in the results. Two cooling mechanisms were examined, one of which is a traditional technique by forced air cooling technology. The other is using graphene nanosheets coating technology to increase the dissipation of the generated heat to the surrounding atmosphere. Although an electronic fan was very effective in cooling the electronic circuit components, which reduced the temperature by 22.6%, it has two undesirable features: the need to install it in a safe place and the need for power to run it. Graphene nanosheets coatings provide efficient and economical heat dissipation. The thin graphene layer enhances the radiation effect for the heat significantly. The results showed that the smooth aluminium plate coated with graphene and mounted directly to the back part of the transistor behind the plastic chip carrier piece for heat dissipation provided an efficient, sustainable and economical solution in thermal management. In comparison with the fan, the graphene nanosheets coating technology reduces the temperature by an average of 16.4% without consuming any energy.

Development of a sensor and measurement platform for water quality observations: design, sensor integration, 3D printing, and open-source hardware.

A measurement and development platform for collecting water quality data (the WaterWatcher) was developed. The platform includes sensors to measure turbidity, total dissolved solids (TDS), and water temperature as variables that are often collected to assess water quality. The design is extensible for research and monitoring purposes, and all the design files are provided under open-source permissive licenses for further development. System design and operation are discussed for illustrative purposes. A block diagram indicates elements of mechanical, electrical, and software design for this system. The mechanical assembly used to house circuit boards and sensors is designed using 3D printing for rapid prototyping. The electronic circuit board acts as a carrier for an Arduino 32-bit microcontroller board and an associated cellular module along with a GPS for geolocation of water quality measurements. The cellular module permits data transfer for Internet of Things (IoT) functionality. System operation is set up using a command line interface (CLI) and C + + code that allows for calibration coefficients and human-readable transfer functions to be defined so that sensor voltages are related to physical quantities. Data are cached on a secure digital (SD) card for backup. The circuit was calibrated, and system operation assessed by deployment on an urban reservoir. Biogeochemical cycles were identified in the collected data using spectrogram and semivariogram analyses to validate system operation. As a system with hardware and software released under an open source license, the WaterWatcher platform reduces the time and effort required to build and deploy low-cost water quality measurement sensors and provides an example of the basic hardware design that can be used for measurements of water quality.

A Portable Device for the Measurement of Venous Pulse Wave Velocity

Pulse wave velocity in veins (vPWV) has recently been reconsidered as a potential index of vascular filling, which may be valuable in the clinic for fluid therapy. The measurement requires that an exogenous pressure pulse is generated in the venous blood stream by external pneumatic compression. To obtain optimal measure repeatability, the compression is delivered synchronously with the heart and respiratory activity. We present a portable prototype for the assessment of vPWV based on the PC board Raspberry Pi and equipped with an A/D board. It acquires respiratory and ECG signals, and the Doppler shift from the ultrasound monitoring of blood velocity from the relevant vein, drives the pneumatic cuff inflation, and returns multiple measurements of vPWV. The device was tested on four healthy volunteers (2 males, 2 females, age 33±13 years), subjected to the passive leg raising (PLR) manoeuvre simulating a transient increase in blood volume. Measurement of vPWV in the basilic vein exhibited a low coefficient of variation (3.6±1.1%), a significant increase during PLR in all subjects, which is consistent with previous findings. This device allows for carrying out investigations in hospital wards on different patient populations as necessary to assess the actual clinical potential of vPWV.