Device Processing Research Articles

Printed circuit board and printed circuit board assembly methods for testing and visual inspection: a review

Testing and visual inspection of printed circuit boards (PCBs) and printed circuit board assemblies (PCBAs) are important procedures in the manufacturing process of electronic modules and devices related to locating and identifying possible defects and failures. Earlier defects detection leads to decreasing expenses, time and used resources to produce high quality electronics. In this paper an exploration and analysis about the current research regarding methods for PCB and PCBA testing, techniques for defects detection and vusial inspection is performed. The impact of machine and deep learning for testing and visual inspection procedures is also investigated. The used methodology comprises bibliometric approach and content analysis of papers, indexed in scientific database Scopus, considering the queries: “PCB and testing” and “PCB and testing”, “printed circuit board assembly and testing” and “PCBA and testing”, “PCB defect detection” and “PCBA defect detection”, “PCB and visual inspection”, and “PCBA and visual inspection”. The findings are presented in the form of a framework, which summarizes the contemporary landscape of methods for PCBs and PCBAs testing and visual inspection.

Numerical simulation research on the launch process of pneumatic launch device

Abstract In order to deal with the potential threats posed by low-altitude UAVs, an anti-UAV net-catching device was designed based on the principle of pneumatic launch. The internal ballistic calculation model of the net-catching device during the launch process was established, and the pressure-stabilizing air chamber of the device was numerically simulated. The impact of pressure, air chamber volume, gas channel diameter and barrel length on the performance of the launch device to capture the UAV was analyzed. The internal relationship between different influencing factors on the muzzle velocity and the air pressure drop of a single shot was analyzed. Selecting appropriate internal ballistic characteristics to capture UAVs at different target distances provides theoretical guidance for in-depth research on anti-UAV netting devices.

Comparison of computer-assisted sperm analysis and smartphone-applied sperm analysis for evaluation of frozen-thawed bull semen.

This study aims to compare the efficacy of computer-assisted sperm analysis (CASA) and smartphone-applied sperm analysis (SASA) in assessing the quality of frozen-thawed bull semen. A total of 75 straws (n = 75) semen samples were used from different production batches of five Holstein bulls. The semen analyses were conducted in three groups: Group I (CASA-37°C), semen samples were evaluated using the CASA system at 37°C (n = 25); Group II (SASA-25°C), semen samples were assessed using the SASA system at a temperature of room heat (25°C) (n = 25); and Group III (SASA-37°C), semen samples were evaluated using the SASA system at 37°C (n = 25). The frozen-thawed bull semen samples were analysed in terms of total motility (TM), progressive motility (PM), immotile, velocity average path (VAP), velocity curve linear (VCL), velocity straight line (VSL) and sperm concentration. There was no significant difference between the groups in terms of spermatozoa concentration (p > .05). However, significant differences among the groups were observed for total motile spermatozoa values (p < .001). Values of progressive motile spermatozoa were lower in Group I and Group II compared to Group III (p < .001). The immotile spermatozoa values were significant between the groups (p < .001) and were found to be proportional to total motile spermatozoa values. Additionally, the VAP, VCL and VSL values were comparable between Group II and Group III, but lower when compared to Group I. In conclusion, the results of the study demonstrate that the Sperm Cell™ system can accurately analyse the concentration of frozen-thawed bull semen. The analyses performed at room temperature indicate a parallelism between the PM value and CASA results. However, it is thought that SASA devices require a series of standardization studies in different semen extenders, different sample concentrations and different animal species, analogous to the standardization evolution process of CASA devices in semen analysis.

Design of image classification system for fabric inspection process using Raspberry Pi

This research is designed as a prototype of defect inspection system on fabric production using machine learning-based image processing technology using the open source Google teachable machine application integrated with Raspberry Pi-3B. The prototype of fabric defect inspection system is built by utilizing two rollers that function as a fabric roll house before and after the inspection process. On both rollers, a fabric is stretched to be inspected, so that from a roll of fabric with a certain length, it can be seen how many defects occur on the fabric. The inspection system is carried out using a web camera with a certain level of lighting connected to a raspberry pi as a control device. Raspberry Pi functions as an image processing device and fabric rolling motor controller. In addition to the category of fabric in good condition, this system classifies into two categories of defects, namely slap defects and sparse defects. The test results show that this system has an average frame per second (FPS) of 4.85, an average inference time of 181.1 ms, with an accuracy of image classification results of 98.4 %.

Silk fibroin as a surfactant for water-based nanofabrication.

Water-based processing plays a crucial role in high technology, especially in electronics, material sciences and life sciences, with important implications in the development of high-quality reliable devices, fabrication efficiency, safety and sustainability. At the micro- and nanoscale, water is uniquely enabling as a bridge between biological and technological systems. However, new approaches are needed to overcome fundamental challenges that arise from the high surface tension of water, which hinders wetting and, thus, fabrication at the bio-nano interface. Here we report the use of silk fibroin as a surfactant to enable water-based processing of nanoscale devices. Even in minute quantities (for example, 0.01 w/v%), silk fibroin considerably enhances surface coverage and outperforms commercial surfactants in precisely controlling interfacial energy between water-based solutions and hydrophobic surfaces. This effect is ascribed to the amphiphilic nature of the silk molecule and its adaptive adsorption onto substrates with diverse surface energy, facilitating intermolecular interactions between unlikely pairs of materials. The approach's versatility is highlighted by manufacturing water-processed nanodevices, ranging from transistors to photovoltaic cells. Its performance is found to be equivalent to analogous vacuum-processed devices, underscoring the utility and versatility of this approach for water-based nanofabrication.

Design and field experiment of Codonopsis pilosula film covering transplanter

To address the low efficiency and high labor demands of manual Codonopsis pilosula cultivation, as well as the limitations of existing flat-type transplanting machines that create trenches of inconsistent depth hindering root growth and seedling emergence, a C. pilosula film-covered outcrop tilted transplanting machine was developed. Based on theoretical analysis of the prototype's key components and agronomic requirements for oblique C. pilosula transplanting, the structure and working parameters of the rotary tiller soil throwing device, soil lifting device, track-type soil conveying device, seedling throwing device, and film covering device were determined. The core components' working principles were analyzed, and the soil throwing process of the rotary tiller device was simulated using the discrete element method (DEM). A calculation domain was established, and the results showed that the average mass of the rotary tiller device was 49.44 kg, while the required soil lifting amount for the scraper-type soil lifting device was 21.84 kg, meeting the soil throwing requirements. Field experiments in 10 test areas demonstrated an average qualified rate of 89.50% for planting depth, 84.00% for planting posture, 90% for exposed plant spacing, 4.51 cm for plant spacing, and 8.67% coefficient of variation for planting spacing. These results meet industry standards for planting depth and planting spacing, confirming the machine's effectiveness in achieving high-quality tilted transplanting of C. pilosula seedlings.

Enhanced fluorescence properties of polyfluorene–based polymer dots through an ascorbic acid-photoaging treatment for living cell imaging

The polymer dots (Pdots) prepared by the conjugated polymer (PFO, poly (9,9-dihexylfluorene-2,7-diyl)) have high fluorescence intensity and are often used in biological fluorescence imaging. However, due to the chain defects, the PFO Pdots suffer from stability issues such as photoinactivation and photobleaching. To solve this problem, we drew inspiration from the preparation process of organic planar light-emitting devices and added an optimization processing after Pdots was prepared. We used illumination as the driving force to activate defects on its chain, and ascorbic acid as a reducing substance to restore the chain defects of the polymer to a more stable state. Through this method, we increased the fluorescence intensity by nearly 1.9 times, and significantly improving their long and short-term stability. In addition, it ensures other properties remain unchanged. This optimization scheme is also fully compatible with the entire biological imaging process, ensuring that other important properties such as cytotoxicity do not undergo unnecessary changes. Furthermore, we conducted material characterization and theoretical simulation, revealing that the optimization scheme mainly serves to repair C-9 alkyl defects on the polyfluorene unit. This study has improved and enhanced the fluorescence performance of PFO Pdots, and also provides a way to optimize the treatment of other similar conjugated polymer material systems.

Broadband vortex beam generation by a reflective meta-surface based on a metal double-slit resonant ring

Recently, the meta-surface (MS) has emerged as a promising alternative method for generating vortex waves. At the same time, MS also faces the problem of a narrow bandwidth; in order to obtain a broad bandwidth, the MS unit cell structure becomes more and more complex, which will bring many inconveniences to the preparation process of MS devices. Therefore, we want to design a simple MS unit cell with a multi-frequency selection. In this paper, based on the principle of geometric phase, we design a simple reflective MS unit cell based on a metal double-slit resonant ring. We elaborate on the resonance mechanism of the MS unit cell. Under the normal incidence of circularly polarized (CP) waves, the reflection coefficient of the same polarization was greater than 85%. By rotating the orientation angle of the resonator on the MS unit cell, the continuous 2π phase coverage was satisfied in the frequency range of 0.52–1.1 THz, and the relative bandwidth becomes 71.6%. Based on this, we construct a vortex generator by using a 15×15 MS unit array. The right-handed circularly polarized (RCP) waves and left-handed circularly polarized (LCP) wave are separately incident on MS with topological charges of l=+1,+2,+3 under multiple resonant frequencies. The generated RCP vortex wave has topological charges of l=−1,−2,−3 and the generated LCP vortex wave has topological charges of l=+1,+2,+3. The numerical simulation results demonstrate that our designed MS, capable of achieving multiple resonance outcomes, can effectively operate in a multi-broadband mode and produce a wide-band vortex beam. In addition, we also calculate the pattern purity. Through theoretical analysis and numerical simulation, we prove that our designed MS can generate a broadband vortex wave.

Control of spin on structural stability, mechanical, magneto-optoelectronic and thermodynamic properties of RbTaX (X =P and As) materials: Emerging candidates for opto-spintronics and spin filter applications

In the present work, the density functional theory has been utilised in inspecting the ground state-structural, electronic, magnetic, optical, elastic and thermodynamic properties of new semiconductor RbTaX (X = P and As) half-Heuslers. Out of the possible three structures (α, β, γ) studied in ferromagnetic (FM) as well as non-magnetic (NM) phases, α – FM phase is found to be the most stable configuration. Both studied materials have estimated a net magnetic moment of 3μB, following the Slater-Pauling rule (Mtot=Ztot−8). With the use of modified Becke Johnson potential (mBJ) potential, the band profile reveals non-zero band gap in the spins and henceforth display spin filter property in the compounds. The predicted energy band gaps for RbTaP and RbTaAs are 3.04 and 2.87 eV for minority spin channels and 0.137 and 0.26 eV for majority spin channels, respectively. This unique feature of the Heusler compound may be advantageous for quantum information processing and spin-transport in electronic and magnetic devices. Also, a moderate exchange splitting and a Curie temperature well above the room temperature are noted. The stability of the materials under investigation was further confirmed by calculations of cohesive energy, formation energy, and second order elastic constants. The optoelectronic as well as thermodynamic properties of the studied compounds are also investigated. The estimated high value of refractive index (>4) is making them suitable for optical lenses. Moreover, photon energy absorption in the visible and ultraviolet spectrums renders them valuable for UV-VIS absorbers.

Rapid Detection of Cleanliness on Direct Bonded Copper Substrate by Using UV Hyperspectral Imaging.

In the manufacturing process of electrical devices, ensuring the cleanliness of technical surfaces, such as direct bonded copper substrates, is crucial. An in-line monitoring system for quality checking must provide sufficiently resolved lateral data in a short time. UV hyperspectral imaging is a promising in-line method for rapid, contactless, and large-scale detection of contamination; thus, UV hyperspectral imaging (225-400 nm) was utilized to characterize the cleanliness of direct bonded copper in a non-destructive way. In total, 11 levels of cleanliness were prepared, and a total of 44 samples were measured to develop multivariate models for characterizing and predicting the cleanliness levels. The setup included a pushbroom imager, a deuterium lamp, and a conveyor belt for laterally resolved measurements of copper surfaces. A principal component analysis (PCA) model effectively differentiated among the sample types based on the first two principal components with approximately 100.0% explained variance. A partial least squares regression (PLS-R) model to determine the optimal sonication time showed reliable performance, with R2cv = 0.928 and RMSECV = 0.849. This model was able to predict the cleanliness of each pixel in a testing sample set, exemplifying a step in the manufacturing process of direct bonded copper substrates. Combined with multivariate data modeling, the in-line UV prototype system demonstrates a significant potential for further advancement towards its application in real-world, large-scale processes.

PDMS micro check valve with 3D valve disk for reducing fluid resistance

Check valves are essential components in various biomedical, chemical, medical diagnostic, and process applications, as they allow fluid flow in the forward direction while blocking the reverse flow. This paper presents a method to enhance the performance of unibody micro check valves composed of polydimethylsiloxane using 3D design and printing technologies. Passive micro check valves, which are known for their structural simplicity, miniaturization, and light weight, have shown improved performance with the application of 3D valve disks formed via 3D printing technology. The performance of various valve disk designs was evaluated using simulations and experiments, which revealed that cone-shaped 3D valve disks offer a 58.33% improvement in blocking pressure performance compared to traditional two-dimensional designs. This underscores the potential for efficient fluid control in micro check valves using 3D structures while highlighting the importance of 3D printing technology in the design and manufacturing processes of microfluidic devices.

Unveiling Energy Conversion Mechanisms and Regulation Strategies in Perovskite Solar Cells.

Despite recent revolutionary advancements in photovoltaic (PV) technology, further improving cell efficiencies toward their Shockley-Queisser (SQ) limits remains challenging due to inherent optical, electrical, and thermal losses. Currently, most research focuses on improving optical and electrical performance through maximizing spectral utilization and suppressing carrier recombination losses, while there is a serious lack of effective opto-electro-thermal coupled management, which, however, is crucial for further improving PV performance and the practical application of PV devices. In this article, the energy conversion and loss processes of a PV device (with a specific focus on perovskite solar cells) are detailed under both steady-state and transient processes through rigorous opto-electro-thermal coupling simulation. By innovatively coupling multi-physical behaviors of photon management, carrier/ion transport, and thermodynamics, it meticulously quantifies and analyzes energy losses across optical, electrical, and thermal domains, identifies heat components amenable to regulation, and proposes specific regulatory means, evaluates their impact on device efficiency and operating temperature, offering valuable insights to advance PV technology for practical applications.

Improving communication and promoting social inclusion for hearing-impaired users: Usability evaluation and design recommendations for assistive mobile applications.

This study examines the usability of communication-assistive applications for hearing-impaired users, with a focus on enhancing user experience and promoting social inclusion. Although such applications have been developed and evaluated previously, interface designs that consider the intimacy needs of hearing-impaired users remain under-explored. We performed a comprehensive usability evaluation employing a mixed-method approach, which involved hearing-impaired individuals as well as field experts. The findings revealed areas for improvement in the design, validated the feasibility of implementing these applications, and emphasized the importance of incorporating the unique needs and preferences of hearing-impaired users. Furthermore, this paper discusses the importance of introducing guidelines and evaluation scales for the "Design for Emotion and Life Knowledge" levels to facilitate smooth and effective human-computer interactions. Such measures will promote the development of intelligent assistive technologies that reflect the qualitative needs of people with disabilities and contribute to social rights for hearing-impaired users. With the growing demands of artificial-intelligence-powered assistive technologies, the inclusion of individuals with disabilities in the design and research process is anticipated to increase. In future, studies should be conducted to blend the culturally shared experiences and emotional bonds expressed by users (having mild-to-severe hearing impairment) with the design and development process of assistive devices or services.

Diamond/graphene (carbon sp3-sp2) heterojunctions for neuromorphic device applications

Diamond/graphene (carbon sp3-sp2) interfaces exhibit various interesting and potentially useful electronic phenomena. The present work demonstrates the possibility of obtaining novel neuromorphic photodevices using such junctions. Junctions were found to show different photoconductivity relaxation behavior depending on their growth conditions such that various optoelectronic properties were observed. In particular, interfaces exhibiting shorter relaxation times could be used to construct image recognition devices mimicking short-term memory functions of the human brain. Using these devices, images of the hand-written numerals 0 through 9 could be optoelectronically recognized with an accuracy on the order of 80%, demonstrating both photo-detection and processing functions in a single device. These results suggest that novel image processing devices could be produced using graphene/diamond heterojunctions.Graphical

Atomic Depth Image Transfer of Large-Area Optical Quartz Materials Based on Pulsed Ion Beam.

The high-efficiency preparation of large-area microstructures of optical materials and precision graphic etching technology is one of the most important application directions in the atomic and near-atomic-scale manufacturing industry. Traditional focused ion beam (FIB) and reactive ion etching (RIE) methods have limitations in precision and efficiency, hindering their application in automated mass production. The pulsed ion beam (PIB) method addresses these issues by enhancing ion beam deflection to achieve high-resolution material removal on a macro scale, which can reach the equivalent removal resolution of 6.4 × 10-4 nm. Experiments were conducted on a quartz sample (10 × 10 × 1 mm) with a specific pattern mask using the custom PIB processing device. The surface morphology, etching depth, and roughness were measured post-process. The results demonstrated that precise control over cumulative sputtering time yielded well-defined patterns with expected average etching depths and surface roughness. This confirms the PIB technique's potential for precise atomic depth image transfer and its suitability for industrial automation, offering a significant advancement in microfabrication technology.

Optoelectronic Devices for In-Sensor Computing.

The demand for accurate perception of the physical world leads to a dramatic increase in sensory nodes. However, the transmission of massive and unstructured sensory data from sensors to computing units poses great challenges in terms of power-efficiency, transmission bandwidth, data storage, time latency, and security. To efficiently process massive sensory data, it is crucial to achieve data compression and structuring at the sensory terminals. In-sensor computing integrates perception, memory, and processing functions within sensors, enabling sensory terminals to perform data compression and data structuring. Here, vision sensors are adopted as an example and discuss the functions of electronic, optical, and optoelectronic hardware for visual processing. Particularly, hardware implementations of optoelectronic devices for in-sensor visual processing that can compress and structure multidimensional vision information are examined. The underlying resistive switching mechanisms of volatile/nonvolatile optoelectronic devices and their processing operations are explored. Finally, a perspective on the future development of optoelectronic devices for in-sensor computing is provided.

Spontaneous symmetry breaking of coupled Fabry–Pérot nanocavities

Ring cavities are quickly emerging as preferential platforms to investigate spontaneous symmetry breaking. However, research on handedness polarisation splitting within Kerr-coupled cavities is yet at a preliminary stage. Here, we observe experimentally spontaneous symmetry breaking in a non-Hermitian coupled Fabry‒Pérot nanocavity. In the experiment, horizontally polarised light is incident on the nanocavities, and symmetry breaking occurs when the power exceeds the symmetry breaking threshold of 8mW\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$8\\,{{\\mbox{mW}}}$$\\end{document}. We interpret such observation via nonlinear coupled mode theory, finding that an excitation power-dependent random splitting of right- or left-handed circular polarisations (RCP and LCP, respectively) emerges at the resonance peak. Further numerical simulations show that when the incident power is above the symmetry breaking threshold, the device exhibits spontaneous symmetry breaking characteristics: an additional polarisation component appears in the output field when the input field is monopolarised, and this is attributed to the imbalance of RCP and LCP. Our findings provide further understanding of spontaneous symmetry breaking in non-Hermitian systems and demonstrate the potential applications of the proposed device in optical signal processing.

A Multi-Channel Data Simulator Based on the Time Unification System

In satellite and airborne electro-optical tracking systems, there are numerous processing devices and complex data flows. To ensure the coordinated operation of the system, the multiple devices within the target system must operate under unified time control for data acquisition, computation, and output. This study introduces a multi-channel data simulator based on a time unification system. The complete simulation system includes the host computer, simulator, target system, and time reference generator. The simulator has programmable input and output interfaces for multi-channel protocols and has storage and real-time working modes. In the storage mode, the simulated data are pre-transmitted to the simulator’s storage and sent to the target system according to the time reference generator. The simulator simultaneously stores the target system results. In the real-time mode, the host computer generates simulated data based on the target system’s results and outputs the data through the simulator in real time. The main contribution of the simulator is that it achieves system-level closed-loop simulation and completes the functional and performance verification of the target system. Through experimental verification, it is found that the simulator can achieve 4.2 Gbps of simulated data transmission and 1.6 Gbps of data reception and storage, with a closed-loop delay of 39.9 µs.

Development and research of filter models communication and control systems configured for the required set of parameters

Problem statement. A digital filter refers to a hardware or software implementation of a mathematical algorithm that converts a digital signal in a certain way. The classification of digital filters is usually based on the functional characteristics of digital filtering algorithms. Digital filters may have parameters that cannot be implemented in analog filters, do not require periodic monitoring and calibration, and one filter can process several input channels or signals, while the accuracy is limited only by the bit depth used. The implementation of digital signal processing units using programmable logic integrated circuits (FPGAs) will significantly simplify hardware costs and make the most effective use of these digital filter capabilities. Goal. Conducting research in the field of digital signal processing in order to obtain fundamentally new software and hardware architectures, developing an RTL model of a complex functional block (SF block) of a digital signal processing system, its verification both at the logical and physical level. Results. In the course of the scientific research, a software and hardware model of the filter was developed to adjust the parameters during operation, taking into account their architectural advantages and disadvantages. In order to verify and confirm the adequacy of the methodology developed in the course of the study, an SF model was created-a digital signal processing unit. This model has been implemented and physically verified on the basis of a debugging board using FPGAs. Practical significance. The technique presented in this paper will allow the development of software and hardware devices for digital signal processing, with the possibility of their configuration at the software level for the required set of processing parameters, which in turn will significantly save resources spent on development.

Methodology for modeling and optimizing liquid cooling plates in the design of electronic equipment

Problem formulation. When solving the problem of excessive heat generation, which occurs when operating radio-electronic devices with a high density of electronic components and increased power, it is necessary to use cooling. Otherwise, this problem can lead to overheating of the electronics, which in turn can cause malfunctions of the devices or even their failure. Purpose. Development of a technique that will improve the cooling process of radioelectronic devices due to op-thymization of the parameters of liquid cooling plates. Results. A mathematical statement was formed, a modeling technique was proposed and procedures for optimizing liquid cooling plates were performed. Based on the developed 3D model of the liquid cooling plate, multivariate analysis procedures have been implemented using modern automated design tools. The liquid cooling system was optimized using modern modeling software, in particular the Solidworks Simulation program. Practical significance. The presented simulation results can be used in designing and creating cooling systems for various devices and devices.