Printed Circuit Board Research Articles

Functionalization Process for Commercial Viability: Oral Leukoplakia Detection Using IL-6 Biomarker

Oral leukoplakia (OL) or white patched in the oral cavity poses a diagnostic challenge in oral health due to its white patches on the oral mucosa, affecting 1%-2% of the population, predominantly those over 40 years old. Despite being often benign, OL often precedes potentially malignant disorders and oral cancer, necessitating early detection and intervention. The search for novel biomarkers has intensified, with interleukin-6 (IL-6) emerging as a promising candidate. IL-6 detection levels in saliva offer a non-invasive approach, aiding an accurate risk assessment and treatment planning. Here, we introduce an IL-6-based biosensor for rapid concentration detection. A novel, hour-long functionalization method streamlines mass production, maintaining a low detection limit down to 10−15 g ml−1, which is three order lower than current commercial ELISA kits, with a sensitivity around 18/dec. Utilizing a specially designed printed circuit board with double pulse technology ensures precise concentration results, with human sample tests confirming the biosensor’s efficacy in real-world applications. This innovation represents a significant advancement in early OL detection, enabling timely intervention to prevent its progression to more severe forms of oral cancer.

Printed Circuit Board Based Rotating Coils for Measuring Sextupole Magnets

Printed Circuit Board Based Rotating Coils for Measuring Sextupole Magnets

Recovery of Copper Layer from Waste Mobile Phone Printed Circuit Board Without Crushing

Resource recovery and material reuse from waste is an art of circular economy. Waste mobile phone printed circuit boards contain a significant amount of nonferrous and precious metals, where copper is one of the dominant nonferrous elements. This paper presents the recovery of copper material using an electrochemical process from three samples of waste mobile phone printed circuit boards, each double-sided, where for sample preparation no crushing and dismantling are applied except that the painting mask is chemically removed. From mass analysis, the gross amount of the recovered copper from the sample materials was 5.94 g and the calculated average was 1.98 g per sample material. In this way, the copper layer from waste mobile phone printed circuit boards could be recovered economically at an early stage, which could reduce complexity and improve further material recovery compared to the traditional crushing practice.

Study of pressure measurement technique using MEMS pressure sensors integrated on built-in printed circuit board

Study of pressure measurement technique using MEMS pressure sensors integrated on built-in printed circuit board

Synthesis and characterization of alkali-activated binders with slag and waste printed circuit board

The global production of printed circuit board (PCB) is expected to rise substantially in the next decade due to the advancement in technology. The production of PCB results in generation of hazardous waste of various kinds, and one such waste is the very fine particles of the board material that is generated due to drilling and other preparatory operations. The disposal of such waste in the environment can result in serious consequences which needs attention. Therefore, recycling of waste printed circuit board (WPCB) can mitigate its harmful effects on the environment and also reduce the remediation costs. In this study, the WPCB is used as a substitute to ground granulated blast furnace slag (GGBFS) in development of alkali-activated binder. Alkali-activated binder was synthesized with GGBFS, WPCB, sodium hydroxide sol. (NaOH), and sodium silicate sol. (Na2SiO3). GGBFS was replaced with WPCB at replacement rates of 0%, 10%, 20%, and 30% by volume. Additionally, the effect of varying concentration of NaOH and Na2SiO3 on the physical and mechanical performance of the binder was studied. The developed binders were evaluated for workability, strength, water absorption, and efflorescence properties. Further, to ascertain its safety on the environment, the toxicity characteristic leaching procedure (TCLP) test was also performed. The results indicate that WPCB characteristics are compatible with GGBFS in terms of its particle size distribution. Moreover, the replacement of GGBFS with up to 20% WPCB provides desirable properties for the alkali-activated binder. However, higher replacements are not recommended, since it had detrimental effect on the mechanical performance of the binder. The study revealed that desirable performance can be achieved for binders with 8 M NaOH and with Na2SiO3 to NaOH ratio of 2, and up to 20% GGBFS replaced with WPCB. The results of TCLP test disclose that the contaminant in the leachate from alkali-activated binders with WPCB are within regulatory limits, and do not pose any threat to the environment. Finally, the outcome of this study provides an innovative approach towards formulation of eco-friendly binder for various construction applications such as foundations, buildings, bridges, pavements, etc.

Acoustic-noise reduction in printed circuit boards based on location and direction of multilayer ceramic capacitors

Acoustic-noise reduction in printed circuit boards based on location and direction of multilayer ceramic capacitors

Elemental Analysis of Discarded Printed Circuit Boards using Different Analytical Techniques and Recovery of Silver

The rapid advancement of technology and the demands of our consumer-driven society significantly contribute to the growing volume of e-waste generated annually. This category includes all discarded components and products from electronic and electrical equipment that are not intended for reuse. Among these, Printed Circuit Boards (PCBs) are essential elements in all electrical and electronic devices and are difficult to reuse or recycle considering the complex structure of PCB. This study focuses on analyzing PCBs for their elemental content and the recovery of precious metal, silver. Elemental concentration was analysed using Neutron Activation Analysis (NAA), nano-colorimetry, potentiometry and Atomic Absorption Spectrometry(AAS) techniques .The findings reveal that Non -metallic part in analysed PCBs is about 80-84 % while among metallic concentrations, copper concentration was found to be highest (42.88-90.80 mg/g) and that of lead lowest (0.26-0.75mg/g).The total amount of silver in three PCB samples is approximately 2 mg/g, with a recovery rate was about 66%. However, the fourth sample contains a lower total amount of silver, with a recovery rate of 52.79%

A Miniaturized High-Gain Router Antenna Pair for 2.4 GHz and 5.0 GHz Frequency Bands

In this paper, we propose a printed circuit board (PCB)-based planar antenna pair, operating at 2.4 GHz and 5.0 GHz frequency bands, respectively, for dual-band routers. The antennas are both rectangular and consist of twisted radiating elements and microstrips etched on an FR4 dielectric substrate. Etching slots on the radiating elements and adjusting the serpentine microstrips influence surface current distribution and therefore effectively reduce antenna size and enhance antenna gain. The proposed antenna features a compact size compared to general router antennas and demonstrates high gain characteristics compared to dipole antennas. In the 2.3–2.5 GHz band, the simulated S11 of the 2.4 GHz antenna was lower than -10 dB, while the gain was 3.9 dBi at 2.4 GHz. In the 5.1–5.9 GHz band, the simulated S11 of the 5.0 GHz antenna was lower than -10 dB, and the gain was greater than 4.8 dBi. The proposed antenna has potential for application to router antennas.

Generalized Huygens' Condition as the Fulcrum of Planar Nonlocal Omnidirectional Transparency: From Meta‐Atoms to Metasurfaces

AbstractFresnel reflection has been known for centuries to fundamentally impede efficient transmittance across planar interfaces, especially at grazing incidence. In this work, the generalized Huygens' condition (GHC) is introduced to resolve such intricacies in metasurface (MS) designs and allow omnidirectional transparency. Compared to common numerical metamaterial approaches, the analytical framework herein yields surprisingly simple closed‐form conditions, carefully leveraging the natural nonlocal mechanisms endowed in planar electromagnetic structures. At the meta‐atom level, the GHC is met by balancing traditional tangential susceptibilities of Huygens' MSs with their unconventional normal counterparts; the latter facilitates the key requisite of vanishing backscattering at the challenging grazing incidence scenario. At the MS level, this central insight is sheerly utilized to engineer realistic all‐angle transparent printed‐circuit‐board (PCB) cascaded admittance sheets. Thoroughly validated in simulation and experiment, this universal GHC demonstrates a resourceful venue for practical implementation of advanced nonlocal devices, e.g., flat optical components, optical analog computers, and spaceplates.

Dependability Assessment of a Dual-Axis Solar Tracking Prototype Using a Maintenance-Oriented Metric System

This study presents a numerical method for evaluating the maintainability of a dual-axis solar tracking system that can be deployed in residential areas for improved energy production. The purpose of this research manuscript is threefold. It targets the following objectives: (i) First, we present the construction of a self-sufficient dual-axis solar tracking system based on a low-power electronic schematic that requires only one motor driver to control the azimuth and elevation angles of the photovoltaic (PV) panel. The automated system’s main electronic equipment comprises 1 × Arduino Mega2560 microcontroller unit (MCU), 1 × TB6560 stepper driver module, 2 × stepper motors, 2 × relay modules, 1 × solar charge controller, 1 × accumulator, and 1 × voltage convertor. Additional hardware components such as photoresistors, mechanical limit switches, rotary encoders, voltage, and current sensors are also included to complete the automation cycle of the solar tracking system. (ii) Second, the Arduino Mega 2560 prototyping board is replaced by a custom-made and low-cost application-specific printed circuit board (ASPCB) based on the AVR controller. The MCU’s possible fault domain is then further defined by examining the risks of the poor manufacturing process, which can lead to stuck-at-0 (Sa0) and stuck-at-1 (Sa1) defects. Besides these issues, other challenges such as component modularity, installation accessibility, and hardware failures can affect the automated system’s serviceability. (iii) Third, we propose a novel set of maintenance-oriented metrics that combine the previously identified variables to provide a maintainability index (MI), which serves as a valuable tool for evaluating, optimizing, and maintaining complex systems such as solar tracking devices. The experimental data show that the computed MI improves the system’s maintainability and enhances repair operations, increasing uptime.

FSPDD: A double-branch attention guided network for few-shot PCB defect detection

AbstractDuring the production of printed circuit board (PCB), there will be defects due to inappropriate operations, which will affect the use of electronic products. Majority defect detection methods cost a large number of annotated samples to train detection models. However, PCB defect samples are difficult to collect. Moreover, existing few-shot object detection methods tend to extracting low-level features from support and query images via the shared backbone such as ResNet-50. However, it is not sufficient to obtain fine-grained prior guidance. To address the above issues, we propose a few-shot PCB defect detection model with double-branch attention. Specifically, the joint attention enhancement (JAE) module is proposed to fully mine effective information of query PCB images in multiple dimensions to enhance the representation of latent defects. Then, the multi-scale guidance (MSG) module is proposed to integrate prior knowledge within support PCB images into vectors to reweight query PCB images. Experiments on the PCB defect dataset demonstrate that AP of FSPDD outperforms state-of-the-art methods under different shot settings (k=1,2,3,5,10,30) and our proposed FSPDD has a good generalization ability, in which AP reachs 0.273 when $$k=30$$ k = 30 and is 5.28% higher than SOTA methods.

A 10 µH Inductance Standard in PCB Technology with Enhanced Protection against Magnetic Fields

Low-frequency working standards of inductance are generally uniformly wound toroids on a ceramic core. Planar inductors made using printed circuit board (PCB) technology are simple and cheap to manufacture in comparison to inductors wound on toroid cores, but they are significantly prone to the influence of external magnetic fields. In this paper, we propose the design of a PCB inductance working standard of 10 μH, consisting of a duplex system of planar PCB coils, electrostatic shielding, and an enclosure. Alongside an electromagnetic analysis and design procedure, the measurements on the manufactured prototype included the generated magnetic field, the thermal time constant of the enclosure, temperature coefficients, and its error analysis. The measurements show negligible generated magnetic fields (<1.68 nT at 7 cm, 49 mA, 10 kHz). The minimum thermal time constant of the enclosure is 1270 s and the temperature coefficient of resistance is 0.00384 1/℃. The presented method of temperature coefficient measurement using a climate chamber allows for measurements in the temperature range of 10 °C to 40 °C. In this temperature range, the results show an inductance variation of 0.05 µH at 50 kHz, while the uncertainty of inductance measurement at this frequency was 0.03 µH (k = 2).

High-precision flexible sweat self-collection sensor for mental stress evaluation

As a stress hormone existing in the human body, cortisol can reflect the psychological stress and health status in daily life, and is a potential biomarker of the body’s stress response. To effectively collect sweat and accurately identify the target, this paper reports a flexible wearable cortisol detection device with outstanding reliability and sensitivity. Molecular imprinted polymer (MIP) ensures cortisol specificity. And carbon nanotubes (CNT) on electrodes increase sensitivity, expanding the detection range to 10−3 to 104 nM, with sensitivity at 189.2 nA/lg(nM). In addition, porous chitosan hydrogel (PCSH) collects sweat effectively, its adhesive properties and 80% swelling rate offer a low-cost alternative to microfluidics. Flexible printed circuit board (FPCB) and serpentine electrode (SE) ensure device durability. This non-invasive, highly sensitive device offers a novel method for mental stress monitoring and clinical diagnosis, advancing human physiological state monitoring.

A hydrometallurgical process for the recovery of copper metal and nickel hydroxide from the aqua regia leaching solutions of printed circuit boards

Leaching solutions of printed circuit boards (PCBs) contain noble and base metal ions. The precious metal ions present in the leaching solutions of PCBs could be separated by cementation with copper metal. After recovery of precious metal ions by cementation, the filtrate contains Cu(II) together with base metal ions like Al(III), Fe(III), Fe(II), Ni(II), Sn(II), and Zn(II). In this work, separation experiments were conducted to recover Cu(II) and Ni(II) from the filtrate. First, copper ions were completely separated from the filtrate by chemical reduction with hydrazine at the following conditions: a molar ratio of 8 for hydrazine to Cu(II), 20°C, 500 rpm, and 20 mins. By adding sodium oxalate to the solution after separation of Cu(II), most of the Ni(II) and 38% of the Zn(II) were co-precipitated at 20°C, 60 mins, 500 rpm, and a molar ratio of 20 for sodium oxalate to nickel. After dissolving the co-precipitates of Ni(II) and Zn(II) oxalates in a 0.5 M HCl solution, the Zn(II) was completely removed from the solution by a five-stage cross-current extraction with 2.5 M Cyanex 272. Nickel hydroxides were then recovered from the raffinate by precipitation with NaOH. The purity of the copper metal and nickel hydroxides was higher than 99%. A process was proposed to recover Au(III), Pd(II), Cu(II), and Ni(II) from the leaching solutions of PCBs.

Design and Analysis of Receiver Coils with Multiple In-Series Windings for Inductive Eddy Current Angle Position Sensors Based on Coupling of Coils on Printed Circuit Boards.

We present a method for improving the amplitude and angular error of inductive position sensors, by advancing the design of receiver coil systems with multiple windings on two layers of a printed circuit board. Multiple phase-shifted windings are connected in series, resulting in an increased amplitude of the induced voltage while decreasing the angular error of the sensor. The amplitude increase for a specific number of windings can be predicted in closed form. Windings are placed electrically in series by means of a differential connection structure, without adversely affecting the signal quality while requiring a minimal amount of space in the layout. Further, we introduce a receiver coil centerline function which specifically enables dense, space-constrained designs. It allows for maximization of the number of possible coil windings while minimizing the impact on angular error. This compromise can be fine-tuned freely with a shape parameter. The application to a typical rotary encoder design for motor control applications with five periods is presented as an example and analyzed in detail by 3D finite-element simulation of 18 different variants, varying both the number of windings and the type of centerline functions. The best peak-to-peak angular error achieved in the examples is smaller than 0.1° electrically (0.02° mechanically, periodicity 5) under nominal tolerance conditions, in addition to an amplitude increase of more than 170% compared to a conventional design which exhibits more than twice the angular error. Amplitude gains of more than 270% are achieved at the expense of increased angular error.

Terminated polymer waveguide with low coupling loss to single-mode fiber for 100 Gbps optical interconnects and beyond.

We designed and fabricated terminated polymer waveguides with low coupling loss to a standard single-mode fiber (SSMF) for 100 Gbps optical interconnects application and beyond. The mode field diameter of the polymer waveguide is designed to perfectly match that of the SSMF with a theoretical coupling loss as small as 0.07 dB. The fabricated polymer waveguides on FR-4 substrates exhibit both a low propagation loss of 0.32 dB/cm and a low coupling loss of less than 0.17 dB to SSMF at a wavelength of 1310 nm. These low loss values indicate good compatibilities with both printed circuit boards and fiber optics. Both single-lane 56 Gbaud (112 Gbps) and 60 Gbaud (120 Gbps) 4-level pulse amplitude modulation (PAM4) optical transmission using terminated polymer waveguides have been successfully demonstrated. The bit error ratio (BER) for PAM4 transmission at both data rates reached a level of 10-4 which is well below the forward error correction (FEC) limitation with a power penalty of less than 1 dB. The bandwidth of the test equipment rather than the polymer waveguide itself limits the high-speed optical interconnect performances in our experiments. The results imply that the polymer waveguide is a promising media for single-lane 100 Gbps optical interconnects application and beyond.

Incorporating long-tail data in complex backgrounds for visual surface defect detection in PCBs

AbstractHigh-quality printed circuit boards (PCBs) are essential components in modern electronic circuits. Nevertheless, most of the existing methods for PCB surface defect detection neglect the fact that PCB surface defects in complex backgrounds are prone to long-tailed data distributions, which in turn affects the effectiveness of defect detection. Additionally, most of the existing methods ignore the intra-scale features of defects and do not utilize auxiliary supervision strategies to improve the detection performance of the network. To tackle these issues, we propose a lightweight long-tailed data mining network (LLM-Net) for identifying PCB surface defects. Firstly, the proposed Efficient Feature Fusion Network (EFFNet) is applied to embed intra-scale feature associations and multi-scale features of defects into LLM-Net. Next, an auxiliary supervision method with a soft label assignment strategy is designed to help LLM-Net learn more accurate defect features. Finally, the issue of inadequate tail data detection is addressed by employing the devised Binary Cross-Entropy Loss Rank Mining method (BCE-LRM) to identify challenging samples. The performance of LLM-Net was evaluated on a homemade dataset of PCB surface soldering defects, and the results show that LLM-Net achieves the best accuracy of mAP@0.5 for the evaluation metric of the COCO dataset, and it has a real-time inference speed of 188 frames per second (FPS).

A high-performance sub-THz planar antenna array for THz sensing and imaging applications

Terahertz (THz) spectral region from 0.1 to 3 THz is envisaged to hold immense potential in the next generation of wireless technologies. Recently, research has focused on this terahertz gap, because of its unprecedented channel capacities. At the physical layer, the design complexities and fabrication of THz devices, especially antennas are the prime bottlenecks to realize its full potential. This article introduces a cost-effective, easy-to-fabricate, and reproducible sub-THz antenna design based on a single-layer planar printed circuit board technology. The antenna incorporates carefully designed quasi-cross slots and applied machine learning-assisted global optimization techniques to achieve the desired performance metrics. The antenna performance is elucidated through numerical simulations and verified through a rigorous in-house THz experimental framework around 100–110 GHz. The proposed antenna offers a peak gain of 13.90 dBi with less than 1 dB variation within the entire band of 100–110 GHz. The antenna holds the potential to achieve terabits per second data rates and futuristic high-resolution short-range THz imaging applications.

Low Temperature Pyrolysis and Exfoliation of Waste Printed Circuit Boards: Recovery of High Purity Copper Foils

Although several techniques have been developed to extract copper from waste printed circuit boards (PCBs), there remain several challenges regarding energy consumption, local area contamination and environmental damage. A novel technique has been developed for extracting copper foils from waste PCBs based on low temperature pyrolysis followed by exfoliation to overcome these issues. The standard pretreatment steps of removing electronic components from PCBs and mechanical processing/size-reduction/powdering, etc., were minimized in this study. Several unsorted ‘as received’ PCBs were heat treated in the temperature range 750–850 °C for 5–20 min. in an argon atmosphere. Brittle dark chars and other residues on the heat-treated specimens were scrapped off to separate copper foils and other residuals. Most of the electronic components mounted on PCBs had dropped off during the heat treatment. Good-quality copper foils were recovered in all cases; the purity of copper was in excess of 85 wt.%. Key impurities present were Pb, Sn and Zn with typical concentrations less than 4 wt.%. Key features of the technique include minimizing energy intensive pre-treatment processes and waste handling, low pyrolysis temperatures and short heating times. This energy-efficient approach has the potential to enhance resource recovery while reducing the loss of materials, local area contamination and pollution near e-waste processing facilities.

Design, preparation and firing characterization of PCB-EBW

Exploding Bridge Wire (EBW) is a special actuator that drives high-temperature and high-pressure plasma. To address the issues of low efficiency and high cost in the preparation process of EBW detonators, an EBW chip based on Printed Circuit Board (PCB) technology was designed and studied. By utilizing a specially designed "S"-shaped transition region and using copper (Cu) as the bridge wire material, the PCB method has enabled batch production of the PCB-EBW device. Four different types of PCB-EBW chips were constructed by designing bridge wires of varying lengths. Subsequently, electro-thermal simulations, electrical explosion performance studies, and shock wave simulations were conducted on the PCB-EBW. It is inferred from the research findings that the main factor triggering the explosive detonation of the PCB-EBW chip is the coupling effect between the high-temperature plasma generated by the electrical explosion and the electrical explosion shock wave. The speculation on the working mechanism of the PCB-EBW was validated by igniting PETN, with the minimum firing voltage determined to be 550 V (for a bridge wire length of 200 μm). This novel EBW design expands the application prospects and provides new insights into the mechanism of EBW for future research.