Printed Wiring Boards Research Articles

أثر استخدام الحاسب الشخصي المدرسي والسبورة التفاعلية لتدريس العلوم في التفكير الإبداعي لتلاميذ الصف الثاني الأساسي في المدارس الخاصة الأردنية

Abstract:This study aimed at inquiring the effect of using School PC and interactive board on creative thinking in science for basic second grade students in private schools. To achieve the objectives of the study, the study applied a Quasi-experimental methodology. Purposive sample was limited to (56) of male and female students, distributed into three groups of 2nd grade in primary schools. The groups were as follows: first experimental group, which was taught Science by using (School PC), second experimental group, which was taught by using (interactive board), and the control group, which was taught by (traditional technique. Torrance's formalism (b) of creative thinking test was adopted and used by the researchers.-There were significant differences at (α≤ 0.05) on originality, fluency, and flexibility dimensions, and the total score between the two groups which were studied by using the interactive blackboard and the usual method, in favor of the usual method. While there were no significant differences at (α≤ 0.05) on the details dimension. -There were significant differences at (α≤ 0.05) on originality, fluency and flexibility dimensions, and the total score between the two groups which were studied by using the interactive blackboard and the school personal computer, in favor of the school personal computer. But, there were no significant differences at (α≤ o.os) on the details dimension. -There were no significant differences at (α≤ 0.05) on originality, fluency, flexibility, details, and the total score between the two groups which were studied by using school personal computer and the usual method. -There were significant differences at (α≤ 0.05) on originality, fluency, flexibility and the total score between the two groups which were studied by using the usual method. -There were significant differences at (α≤ 0.05) on originality, fluency, flexibility and the total score between the two groups which were studied by using the interactive blackboard, and the school personal computer, in favor of the school personal computer. -There were no significant differences at on originality, fluency, flexibility, details and the total score on the creative thinking test, between the two groups which were studied by using the school personal computer, and the usual method. -There were no significant differences at (α≤ 0.05) among the three groups (the school personal computer, the interactive blackboard and the usual method) on details dimension. Key words: School PC, Interactive Board, Creative Thinking.

Electro dynamic fragmentation of printed wiring boards as a preparation tool for their recycling

The use of Electro Dynamic Fragmentation (EDF) enables selective fragmentation of materials through generating electrical discharges as a means of fracturing. Liberated materials can be thus processed downstream in a more efficient way especially when value-added End-of-Life (EoL) electronic equipment is recycled. The aim of this study was to assess the benefits of the EDF technology towards processing of EoL printed wiring boards (PWBs) in view their recyclability. Printed wiring boards were comminuted using EDF at three different settings and with a hammer mill for comparative experiment. The products coming out were characterized by optical microscopy, SEM and liberation oriented leaching. Subsamples from the various EDF stages were inspected to investigate the progress of cracks and degree of copper layers exposure. The different energy levels used during the EDF processing have resulted in different degrees of PWBs damages, starting from components removal to entire structure perturbation and size reduction. EDF has resulted in generation of a lesser amount of fines, however the optimal approach in view energy efficient post-processing of the studied PWBs was the combination between single-stage EDF for components removal only with subsequent shredding of the depopulated boards.

The determination of the thickness of the layers deposited on the electronic circuit boards through tribological methods

The purpose of the paper is to determinate the thickness of the copper layer deposit on the electronic circuit boards, the thickness of the soldering alloy SAC 307 (96.5%Sn/3.0%Ag/0.7%Cu) deposit on the copper-PCB assembly used in electronic industry and also to determinate the sliding length of the sphere on those materials. Slurry composed of water and SiC was used to reduce the testing time. For the experiment a CSEM Calowear equipment was used and the tested materials were the layer of FR4(flame retardant 4) with copper deposit and the soldering alloy SAC 307.

Novel Wiring Structure for 3D-Conformable Devices

Wearable products or biosensors require conformability to a complex curved surface or stretching and moving shapes such as parts of the human body. However, it is difficult to apply conventional printed wiring boards (PWBs) or flexible printed circuits (FPCs) to these applications. This situation prompted us to develop a novel wiring structure suitable for 3D-conformable devices. Our structure is composed of spiral-shaped metal wiring and a polymeric insulating layer that has a similar shape. This wiring structure has the following key features: (1) 3D conformability that combines deformability with robustness, (2) low and unchanging electrical resistance during stretching, and (3) a process applicability that allows solder mounting processes or photo processes to be employed to manufacture this device. In this paper, we show the advantages of this structure compared to other conventional types. We also demonstrate a conformable LED matrix display in which LED chips are mounted at the center of each spiral in the array.

Electroless Copper Plating Process by Applying Alternating One-Side Air Stirring Method for High-Aspect-Ratio Through-Holes

A new electroless copper plating process, namely, an alternating one-side air stirring method, was studied to improve the throwing power of high-aspect-ratio through-holes in multilayer printed wiring boards. The throwing power can even be improved for through-holes of a 40-aspect ratio under an appropriate flow velocity of the solution because the generation of differential-pressure between the front and the back of the board enhances supplying the solution into the through-holes. The necessary flow velocity can be estimated by considering the consumption rate of copper ions in a through-hole and calculating it on the basis of Bernoulli's and Hagen-Poiseuille's equation.

Mixed Integer Programming Approaches to Planning and Scheduling in Electronics Supply Chains

This paper discusses mixed integer programming (MIP) approaches to planning and scheduling in electronics supply chains. First, the short-term detailed scheduling of wafer fabrication in semiconductor manufacturing and detailed scheduling of printed wiring boards assembly in surface mount technology lines are discussed. Then, the medium-term aggregate production planning in a production/assembly facility of consumer electronics supply chain is described, and finally coordinated aggregate planning and scheduling of manufacturing and supply of parts and production of finished products is presented. The decision variables are defined and MIP modelling frameworks provided. The two decision-making approaches are discussed and compared: integrated (simultaneous) approach, in which all required decisions are made simultaneously using a complex, large monolithic MIP model; and hierarchical (sequential) approach, in which the required decisions are made successively, using hierarchies of simpler and smaller-size MIP models. The paper highlights also the research on stochastic MIP applications to planning and scheduling in electronics supply chains with disrupted material and information flows due to natural or man-made disasters.

Wide-aperture aspherical lens for high-resolution terahertz imaging.

In this paper, we introduce wide-aperture aspherical lens for high-resolution terahertz (THz) imaging. The lens has been designed and analyzed by numerical methods of geometrical optics and electrodynamics. It has been made of high-density polyethylene by shaping at computer-controlled lathe and characterized using a continuous-wave THz imaging setup based on a backward-wave oscillator and Golay detector. The concept of image contrast has been implemented to estimate image quality. According to the experimental data, the lens allows resolving two points spaced at 0.95λ distance with a contrast of 15%. To highlight high resolution in the THz images, the wide-aperture lens has been employed for studying printed electronic circuit board containing sub-wavelength-scale elements. The observed results justify the high efficiency of the proposed lens design.

Characterizing the Natural Temperature and Humidity Environment Severity

Abstract Severe yet common product environmental tests are 1000 hours at 85 °C/85% RH or 95 °C/95% RH for products, circuit card assemblies, and electronic components. Such environments never occur naturally; however, they attempt to simulate the corrosion damage that could be expected in service. To what natural environment do these tests correlate? Further, how do tests based on MIL-HDBK-310, MIL-STD-810, and STANAG 2895 B3 daily environments compare to these standard test environments? The analysis employs the Physics-of-Failure (POF) Peck power law temperature-humidity model with common conservative values for the Arrhenius activation energy and the relative humidity exponent, based on aluminum corrosion, coupled with climatological data from 49 United States weather stations and 19 international locations. The monthly average temperature and humidity extremes were transformed into an hourly diurnal cycle assumed to occur every day of each month. Using the power law model the equivalent time at the test condition was calculated for each day, and summed for each month and location. The 85 °C/85% RH test can be correlated with about 10 years in a hot and moist natural environment, such as Singapore, with 1000 hours of 95 °C/95% RH exposure equivalent to 25 years. Long-term tests based on the worst-case diurnal temperature and humidity cycles in military standards are on the order of 1 in 1,000,000 probability of occurrence in nature.

RTミドルウェアを用いたIoT教育教材開発とその運用

In developing the lecture to learn the concept of IoT by lecture and practical skills, teaching materials for practical skills were developed using RT-Middleware. In realizing from sensing to data aggregation and visualization via network, RT-Middleware maintains effectiveness from single board PC utilization to load distribution and network access, and it was informative to realize intuitive teaching material development in a short time. Discuss the effectiveness with the past two operation experiences.

Non‐unicity of the electric near‐field planar emission model with dipole array

This study deals with the behavioural modelling of the planar electric- (E-) near-field (NF) emission from electronic printed circuit boards. The methodology indicating how to synthesise the model from the given scanned E-NF maps in the observation plane of interest is established. The modelled radiation source is built with exclusively E-dipole array whose components are determined by the inverse method. After computational routine algorithm Matlab implementation, the proposed model was validated with various demonstrators. Relevant verifications were performed at different operating frequencies with the E-NF emission from analytical radiation, measurement scanning with active complex RF PCB and full wave simulation with microwave passive microstrip structure. It was shown that the model enables to reproduce the equivalent source with relative error vector magnitude accuracy less than 3%. The error analyses in function of the distance between the observation plane and the radiating PCB were proposed. Moreover, the non-unicity and limit of the model with the E-field emission prediction from different E-field radiated data defined in the scanning observation surface plane positions from the radiating circuit. The developed model can be potentially used to lower the cost of EM compatibility engineering during the electronic PCB design phase.

The prototype design and tests of vibration controlled driver warning system from the steering wheel

In this study, drivers are warned according to detected adverse driving conditions by miniature vibration motors positioned on the steering wheel by obtained information from sensors such as acceleration sensor placed in the center gravity of vehicle, the proximity sensor placed on the rear bumper and rain sensor placed in fender. For this purpose, two different electronic circuit boards are used including firstly center gravity placed in vehicle that has collected signals from sensors and secondly center steering wheel that controlled the miniature vibration motors placed on the steering wheel cover. Wireless communication was established between the two electronic circuit boards. Tests was carried out in real road conditions; it was determined that drivers are warned on steering wheel with vibrations at the different durations (180 Hz frequency) according to the scenario developed for adverse driving conditions using accelerometer sensor, proximity sensor and the rain sensor. It was seen that the developed prototype can be used on available vehicles with small modifications, with a simple montage for a vehicle in the production process.

Evolution of Hardware Morphology of Large-Scale Computers and the Trend of Space Allocation for Thermal Management

Thermal management of very large-scale computers will have to leave the traditional well-beaten path. Up to the present time, the primary concern has been with rising heat flux on the integrated circuit chip, while a space has been available for the implementation of high-performance cooling design. In future systems, the spatial constraint will become a primary determinant of thermal management methodology. To corroborate this perspective, the evolution of computer's hardware morphology is simulated. Simulation tool is the geometric model, where the model structure is composed of circuit cells and platforms for circuit blocks. The cell is the minimum circuit element whose size is pegged to the technology node, while the total number of cells represents the system size. The platforms are the models of microprocessor chips, multichip modules (MCMs), and printed wiring boards (PWBs). The major points of discussion are as follows: (1) The system morphology is dictated by the competition between the progress of technology node and the demand for increase in the system size. (2) Only where the miniaturization of cells is achieved so as to deploy a system on a few PWBs, ample space is created for thermal management. (3) In the future, the cell miniaturization will hit the physical limit, while the demand for larger systems will be unabated. Liquid cooling, where the coolant is driven through very long microchannels, may provide a viable thermal solution.

Characteristics of End‐of‐Life Printed Wiring Boards Processed by Electrodynamic Fragmentation

AbstractElectrodynamic fragmentation (EDF) is an innovative technique which enables selective fragmentation of material. Its inherent selective breakage principles enable liberation while avoiding fine grinding. In this study, the specific effects of the EDF on end‐of‐life printed wiring boards have been assessed. A novel methodology for their EDF processing has been developed and compared with hammer mill shredding. Various energy inputs and treatment stages have resulted in fragmentation degrees ranging from removal of components to structure delamination and subsequent size reduction.

MEMS Packaging Reliability in Board-Level Drop Tests Under Severe Shock and Impact Loading Conditions–Part I: Experiment

The continuing increase of functionality, miniaturization, and affordability of handheld electronic devices has resulted in a decrease in the size and weight of the products. As a result, printed wiring assemblies (PWAs) have become thinner and more flexible, and clearances with surrounding structures have decreased. Therefore, new design rules are needed to minimize and survive possible secondary impacts between PWAs and surrounding structures because of the consequential amplification in acceleration and contact stress. This paper is the first of a two-part series and focuses on the drop test reliability of commercial off-the-shelf microelectromechanical systems (MEMS) components that are mounted on printed wiring boards (PWBs). Particularly in this paper, we are interested in gaining preliminary insights into the effects of secondary impacts (between internal structures) on failure sites in the MEMS assemblies. Drop tests are conducted under highly accelerated conditions of 20 000 ${g}$ (“ ${g}$ ” is the gravitational acceleration). Under such high accelerations, the stress levels generated are well beyond those expected in conventional qualification tests. Furthermore, secondary impacts of varying intensities were allowed by changing the clearance between the PWB and the fixture. As a result, the stress and accelerations are further amplified, to mimic unexpected secondary impacts in a product if/when design rules fail to avoid such conditions. The amplification of the test severity is quantified by comparing the characteristic life ( $\eta $ in a Weibull distribution) of all the tested MEMS components at each clearance. Multiple failure sites from drop testing are identified, from packaging-level failures to MEMS device failures. The participation of competing failure sites is also demonstrated via characteristic life representations of each failure site at various clearances.

MEMS Packaging Reliability in Board-Level Drop Tests Under Severe Shock and Impact Loading Conditions—Part II: Fatigue Damage Modeling

Damage in handheld electronic devices due to accidental drops is a critical reliability concern. This paper is the second of a two-part series and focuses on damage models for drop test durability of commercial off-the-shelf microelectromechanical systems (MEMS) components that are mounted on printed wiring boards. The modeling approach is based on the experimental results presented in the first part of this two-part series. In particular, the focus of this paper is on damage due to drop events under extremely high accelerations (20 $000g$ , where $g$ is the gravitational acceleration) achieved by a series of secondary impacts. Impacts with such high accelerations can occur in handheld electronic devices due to collisions between internal neighboring structures and can generate stress levels well beyond levels previously anticipated in typical use, or in conventional qualification tests. A calibrated dynamic multiscale finite element model is used to evaluate the stresses at the relevant failure sites. Utilizing the local stress at each failure site, a fatigue damage modeling approach is proposed to predict the interaction of the competing failure mechanisms in MEMS components. The proposed damage model is based on the deviatoric stress (or strain) at the failure site and uses a hydrostatic stress correction factor to address the influence of mean stress (depending on component orientation). The model estimates the damage accumulation rate for a given stress condition and integrates the accumulated damage over the entire response history. This approach makes it possible to address the influence of the post-impact transient response on fatigue damage accumulation. The damage-model constants are determined for each failure site of interest by relating the failure data to the corresponding stress/strain metrics. Damage modeling results are not only capable of matching the lifetimes of MEMS components in drop testing, but also provide an explanation of transitions in dominant failure sites observed in MEMS assemblies under different drop conditions.

Bayesian analysis of low-cycle fatigue failure in printed wiring boards

In this study, a low-cycle fatigue experiment was conducted on printed wiring boards (PWB). The Weibull regression model and computational Bayesian analysis method were applied to analyze failure time data and to identify important factors that influence the PWB lifetime. The analysis shows that both shape parameter and scale parameter of Weibull distribution are affected by the supplier factor and preconditioning methods Based on the energy equivalence approach, a 6-cycle reflow precondition can be replaced by a 5-cycle IST precondition, thus the total testing time can be greatly reduced. This conclusion was validated by the likelihood ratio test of two datasets collected under two different preconditioning methods Therefore, the Weibull regression modeling approach is an effective approach for accounting for the variation of experimental setting in the PWB lifetime prediction.

Pulse Laser Irradiation Control Method for Blind Via-Hole Drilling of Printed Wiring Boards Based on High-Speed Camera Monitoring

In recent years, the performance and miniaturization of portable information devices have rapidly advanced. The build-up process is often used in the manufacturing of printed wiring boards (PWBs) for high-density circuits. At present, CO2 laser beams are generally used in the build-up process to drill blind via holes (BVHs) that connect copper foils. However, Cu direct drilling is problematic in that it produces a copper overhang as a result of copper and resin, with different decomposition points, being melted simultaneously. Overhang could cause an adverse effect in plating the hole for connectivity. However, only few studies have investigated Cu direct processing for drilling BVHs. At an actual production site of PWBs, the number of processing holes is enormous, which leads to neglecting the quality of each processed hole. Therefore, we focused on pulse drilling, which involves laser irradiation using short multiple pulses to reduce the thermal effect. Pulse drilling could reduce overhang compared to single pulse irradiation; however, it lengthens the total processing time. Pulse irradiation after BVH formation would be unnecessary, since it could cause thermal damage to the hole and lengthen the processing time. Therefore, during pulse irradiation, it is essential to distinguish whether a BVH is formed. We observed the value of the motion graph, which was acquired from the high-speed camera images. The motion graph shows the luminance value of an image at a given time of the video. Based on the peak time of the motion graph during each pulse, we proposed a method to distinguish BVH formation during multiple pulse drilling.

Thermal stability and fire behavior of aluminum diethylphosphinate-epoxy resin nanocomposites

The flame retardancy of 2, 2-bis(4-glycidyloxyphenyl)propane (DGEBA)-aluminum diethylphosphinate (AlPi) nanocomposites (EP-AlPi/(P − x), x = 1, 2, 3 %) was greatly enhanced by ultrasonic dispersion of nano-sized AlPi into epoxy resin. The UL 94 V-0 rating can be reached for EP-AlPi nanocomposites with a relatively low addition amount of AlPi (on the account of 8.4 wt% or phosphorus content of 2 wt%) as well as the LOI value over 37.2. The glass transition temperature (Tg) enhanced properties were investigated by DTA, which showed that: Tgs were about 5 °C higher than that of neat epoxy resin; Tg increased along with content increasing of AlPi. Based on TGA results under a non-isothermal condition, the thermal degradation kinetics of EP-AlPi/(P − x) composites were studied by Kissinger’s, Ozawa’s, Flynn–Wall–Ozawa’s and Coast-Redfern’s methods, which suggested the conversion function f (α) = 1/2α−1 or f (α) = [−ln(1 − α)]−1 for EP-AlPi/(P − 1 %); f (α) = [−ln(1 − α)]−1 for EP-AlPi/(P − 2 %) and EP-AlPi/(P − 3 %) during the investigated process. The epoxy resin nanocomposites obtained in this study are green functional polymers and will become flame retardant potential candidates in electronic fields such as printed wiring boards with high performance.

Efficacy of computer-based endoscope cleaning and disinfection using a hospital management information system

The present study aimed to assess the efficacy of computer-based endoscope cleaning and disinfection using a hospital management information system (HMIS). A total of 2,674 gastroscopes were eligible for inclusion in this study. For the processes of disinfection management, the gastroscopes were randomly divided into 2 groups: gastroscope disinfection HMIS (GD-HMIS) group and manual group. In the GD-HMIS group, an integrated circuit card (IC card) chip was installed to monitor and record endoscope cleaning and disinfection automatically and in real time, whereas the endoscope cleaning and disinfection in the manual group was recorded manually. The overall disinfection progresses for both groups were recorded, and the total operational time was calculated. For the GD-HMIS group, endoscope disinfection HMIS software was successfully developed. The time to complete a single session of cleaning and disinfecting on a gastroscope was 15.6 minutes (range, 14.3-17.2 minutes) for the GD-HMIS group and 21.3 minutes (range, 20.2-23.9 minutes) for the manual group. Failure to record information, such as the identification number of the endoscope, occasionally occurred in the manual group, which affected the accuracy and reliability of manual recording. Computer-based gastroscope cleaning and disinfection using a hospital management information system could monitor the process of gastroscope cleaning and disinfection in real time and improve the accuracy and reliability, thereby ensuring the quality of gastroscope cleaning and disinfection.

Surface Modification of PTFE Using Low‐Energy Nitrogen Ion Irradiation: Improvement in Adhesive Strength on Modification of Deep Modifying Layer

SUMMARYPolytetrafluoroethylene (PTFE) has the best properties as a material of high‐frequency PC board. However, it has low adhesion force for using cabling material. In order to improve adhesion force, we studied on surface modification of PTFE by using nitrogen ion irradiation. As a result, peel strengths of PTFE improved up to 900 N/m to amount of treatment time. On the other hand, surface energy did not increase. From here onward, improved peel strengths on modified surface could be forecasted because of a change that is binding state of modified layer. The compositions of surface on samples after peel test were analyzed so as to prove the hypothesis. As a result, adhesive/PTFE system occurred to destruction in deep portion of modified layer. Moreover, binding of oxygen could be existed with long treatment time. Therefore, it was suggested that the brittle layer of deep modifying layer needs to be modified for the improvement of adhesive strength.