Printed Wiring Boards Research Articles

MODELLING FINE SCALE MOVEMENT CORRIDORS FOR THE TRICARINATE HILL TURTLE

Abstract. Habitat loss and the destruction of habitat connectivity can lead to species extinction by isolation of population. Identifying important habitat corridors to enhance habitat connectivity is imperative for species conservation by preserving dispersal pattern to maintain genetic diversity. Circuit theory is a novel tool to model habitat connectivity as it considers habitat as an electronic circuit board and species movement as a certain amount of current moving around through different resistors in the circuit. Most studies involving circuit theory have been carried out at small scales on large ranging animals like wolves or pumas, and more recently on tigers. This calls for a study that tests circuit theory at a large scale to model micro-scale habitat connectivity. The present study on a small South-Asian geoemydid, the Tricarinate Hill-turtle (Melanochelys tricarinata), focuses on habitat connectivity at a very fine scale. The Tricarinate has a small body size (carapace length: 127–175 mm) and home range (8000–15000 m2), with very specific habitat requirements and movement patterns. We used very high resolution Worldview satellite data and extensive field observations to derive a model of landscape permeability at 1 : 2,000 scale to suit the target species. Circuit theory was applied to model potential corridors between core habitat patches for the Tricarinate Hill-turtle. The modelled corridors were validated by extensive ground tracking data collected using thread spool technique and found to be functional. Therefore, circuit theory is a promising tool for accurately identifying corridors, to aid in habitat studies of small species.

MODELLING FINE SCALE MOVEMENT CORRIDORS FOR THE TRICARINATE HILL TURTLE

Habitat loss and the destruction of habitat connectivity can lead to species extinction by isolation of population. Identifying important habitat corridors to enhance habitat connectivity is imperative for species conservation by preserving dispersal pattern to maintain genetic diversity. Circuit theory is a novel tool to model habitat connectivity as it considers habitat as an electronic circuit board and species movement as a certain amount of current moving around through different resistors in the circuit. Most studies involving circuit theory have been carried out at small scales on large ranging animals like wolves or pumas, and more recently on tigers. This calls for a study that tests circuit theory at a large scale to model micro-scale habitat connectivity. The present study on a small South-Asian geoemydid, the Tricarinate Hill-turtle (<i>Melanochelys tricarinata</i>), focuses on habitat connectivity at a very fine scale. The Tricarinate has a small body size (carapace length: 127–175 mm) and home range (8000–15000 m<sup>2</sup>), with very specific habitat requirements and movement patterns. We used very high resolution Worldview satellite data and extensive field observations to derive a model of landscape permeability at 1 : 2,000 scale to suit the target species. Circuit theory was applied to model potential corridors between core habitat patches for the Tricarinate Hill-turtle. The modelled corridors were validated by extensive ground tracking data collected using thread spool technique and found to be functional. Therefore, circuit theory is a promising tool for accurately identifying corridors, to aid in habitat studies of small species.

Is data mining of manufacturing data beyond first order analysis of value? A case study

This research-in-progress paper describes a study of data mining using historical manufacturing test data at an electronic circuit board assembly firm. The purpose of this data mining is to determine, if in a multi-step manufacturing process at small and medium manufacturing firm downstream production problems can be identified and prevented by evaluating up stream data. While quantitative analysis and data mining have been used in manufacturing, the scope of their application is generally limited to a specific step or process that is a first order analysis of the data.

Plasma-Generated Etchback to Improve the Via-Reliability in High-Tg Substrates Used in Multilayer PWBs for Space Electronic Packaging

High-Tg (glass transition temperature, 210 °C) woven fiber-glass reinforced multifunctional-epoxy FR-4 laminates are now becoming main trend in the fabrication of multilayer printed wiring boards (PWBs) for space application due to their inherent properties of better dimensional stability, low coefficient of thermal expansion, and the capability to withstand multiple soldering operations. In PWBs, positive etchback is a key factor to improve the plated through hole (PTH) reliability due to enhanced bond pull strength. However, high-Tg multifunctional-epoxy FR-4 laminates have higher chemical resistance, and hence, it is very difficult to get required levels of positive etchback (10– $13~\mu \text{m}$ ). The absence of positive etchback results in inadequate bond pull strength, which can lead to critical defects, such as inner layer separation, and fails to meet the basic requirements of interconnection reliability tests, such as rework simulation test and thermal stress test. Ability to withstand required number of rework simulations (five times of soldering and desoldering) and multiple thermal stress tests (generally—three times solder dips and enhanced performance—six times solder dips) is essential for all PWBs used in space electronic packaging. The popular method to get the positive etchback in drilled holes of low-Tg Printed Circuit Board (PCB) substrates prior to metallization is by chemical desmearing/etchback process. Based on the success rate of chemical desmear methods on low-Tg PCB laminates, experiments were carried out on high-Tg (210 °C) FR-4 laminates. With the experimental results, it is evident that the chemical desmearing method cannot generate the required levels of positive etchback on high-Tg multifunctional-epoxy FR-4 laminate, and sometimes, it leads to negative etchback, which degrades the reliability of PTH in PWBs. In this paper, the effect of plasma treatment—a dry process to get required level of positive etchback in high-Tg multifunctional-epoxy FR-4 laminates is studied at different vacuum levels. It is observed from the experiment that effective plasma treatment to get 10–13- $\mu \text{m}$ positive etchback is possible only at 30 mtorr and higher vacuum levels at optimized plasma etch parameters. Plasma-treated PTH of high-Tg multifunctional-epoxy FR-4 laminates exhibit higher bond pull strength and readily withstand over six dip thermal stress tests and rework simulation tests without any defect in the PTH barrel. Enhanced bond pull strength of deposited copper in the PTH barrel is attributed to the mechanical interlocking of plated copper inside the microroughened dielectric surface, which results in highly reliable 3-D contacts between the plated copper and the projected inner layer copper.

Autonomous Wearable System for Vital Signs Measurement With Energy-Harvesting Module

The growing demand for wearable devices is imposed by the ability to monitor in real-time critical situations in the different areas of daily life. In many cases, power is the limiting factor for such devices. One aspect is the power supply with batteries that introduces issues due to the weight, the overall dimensions, and the disposal of the batteries. A viable solution to overcome the limitations of batteries as power source is to harvest ambient energy to power the devices directly. In this paper, a proposed wearable device with an energy-harvesting module has been designed, manufactured, and tested for the measurement of vital signs. The energy-harvesting module is implemented to directly power the electronic circuit board by a flexible solar panel. This paper describes the proposed instrumented autonomous T-shirt powered by the flexible solar panel applied directly on the T-shirt. The instrumented T-shirt is capable of measuring respiration rate, heart rate, and movement of the body. The methodology adopted, the design choices, and the experimental results are clearly reported and discussed. The experimental results show the functioning even with poor outdoor lighting conditions and under specific indoor constraints. Tests have been conducted aiming to compare the instrumented T-shirt’s output data with the data obtained via instruments as gold standards and to show that the overall system described in this paper is capable of producing reliable data compared with the data obtained with these instruments.

Real-Time Fault Detection and Diagnosis System for Analog and Mixed-Signal Circuits of Acousto–Magnetic EAS Devices

The paper discusses fault diagnosis of the electronic circuit board, part of acousto–magnetic electronic article surveillance detection devices. The aim is that the end-user can run the fault diagnosis in real time using a portable FPGA-based platform so as to gain insight into the failures that have occurred.

Investigating the heat transfer on the top side of inclined printed circuit boards during vapour phase soldering

In this paper, heat transfer and condensate layer formation was investigated by numerical simulations on the top side of inclined printed circuit boards during vapour phase soldering. The phase change on the inclined surface and the transfer mechanisms in the condensate layer were embedded in a three-dimensional model. Steady-state and saturated vapour conditions were applied as boundary conditions in order to study the pure effect of the inclination. Due to the electronic component and circuit board structures during soldering only moderate inclination angles were studied between 0° and 10°. It was found that a moderate inclination of the printed circuit board has considerable effects on the formation of condensate layer and consequently on heat transfer. Compared to the default horizontal orientation of the board, the thickness differences of the condensate layer can be decreased with an optimised inclination of the printed circuit board. This effect homogenizes heat transfer during the process, enabling improved solder joint quality, with reduced overall soldering failure count.

Environmental impacts at the end of life of computers and their management alternatives in México

A Life Cycle Analysis of End-of-Life Computers was developed for management of computers discarded in Mexico for the year 2014 through LCA methodology (ISO 14044) and using specialized software named Umberto® version 5.5.4 with database Ecoinvent 2.2. The modeling consisted in the current scenario in Mexico (10% recycling) versus four alternative scenarios: 0% recycling, 25% recycling, 35% recycling and elimination of open dump disposal considering experience in other countries and real possibilities of medium-term management. All practices of management and recycling are considered in the model with changes in the recycling rates and installed infrastructure for different alternatives proposals. On the other hand, the model included that dismantling operations are done mostly with manual labor; transportation, extraction and processing of printed wiring boards, including local process of transforming, heating and melting of materials and considering recycling in Asian countries with all the environmental burdens processes involving transoceanic transportation and metallurgy. The majority of non-precious metals recycling was considered to take place locally. A substantial benefit was identified for all recycling scenarios, particularly in the elimination of open dump disposal and the recycling of 35% of the stream and was found that there was a high impact on climate change and adverse toxic effects to health and natural environments for the practice of accumulating waste in sanitary landfills and dumpsites as well as by burning of materials (plastics and others) in open areas. The use of recycled materials versus virgin materials was also beneficial up to 10 times for reduction in global warming potential impact and up to 3 times reduction for human toxic potential. Public policies might be recommended in order to protect health and environment. As public policy recommendations, it is proposed reinforcement the national infrastructure to collect EoL computers- and transformation of materials into new commercial products, and as a starting point for the recycling of all generated materials, including plastics and printed wiring boards, but should also include the promotion of research for the transformation of plastic waste and the implementation of new technologies that can be adopted by the national recycling industry and create new regulations that result in the production or import of EoL computers and other electronics with low levels of toxic substances as their main components. Other public policies should include the legal prohibition of use of landfills and dumps for containment of EoL computers and other electrical and electronic equipment.

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Influence of Secondary Impact on Printed Wiring Assemblies—Part I: High-Frequency “Breathing Mode” Deformations in the Printed Wiring Board

Design rules for portable electronic device are continuously striving for thinner printed wiring assemblies (PWAs) and smaller clearances because of ever-increasing demand for functionality and miniaturization. As a result, during accidental drop and impact events, there is an increased probability of internal secondary impact between a PWA and adjacent internal structures. In particular, compared to the initial impact, acceleration pulses caused by contact during secondary impacts are typically characterized by significant increase of amplitudes and frequency bandwidth. The resonant response in the thickness direction of printed wiring boards (PWBs) (termed the dynamic “breathing mode” of response, in this study) acts as a mechanical bandpass filter and places miniature internal structures in some components (such as microelectromechanical systems (MEMS)) at risk of failure, if any of them have resonant frequencies within the transmitted frequency bandwidth. This study is the first part of a two-part series, presenting qualitative parametric insights into the effect of secondary impacts in a PWA. This first part focuses on analyzing the frequency spectrum of: (i) the impulse caused by secondary impact, (ii) the energy transmitted by the dynamic “breathing” response of multilayer PWBs, and (iii) the consequential dynamic response of typical structures with high resonant frequencies that are mounted on the PWB. Examples include internal deformable structures in typical surface mount technology (SMT) components and in MEMS components. The second part of this series will further explore the effects of the breathing mode of vibration on failures of various SMT components of different frequencies.

Knowledge Based Approach For Fault Diagnosis In Electronic Circuit Boards

Knowledge Based Approach For Fault Diagnosis In Electronic Circuit Boards

Thermal Performance Evaluation of a Phase Change Material Based Heat Sink: A Numerical Study

This paper numerically investigates the thermal performance of a portable electronic device using PCM based heat sink. The phase change material used in the present study is n-eicosane with a melting point of 36.50C. Considering the current trend in portable electronic devices, a group of smart phones were taken and an average dimension was selected for designing a PCM based heat sink. A constant heat flux is provided at the heat sink bottom for simulating the heat generation by the electronic circuit board. Numerical analysis were performed for a constant heat input of 4 to 6W in steps of 0.5W on this heat sink to study its effect in conjunction with PCM in the efficient cooling of these devices. The effect of natural convention within the melt is also discussed in this paper. All the numerical computations were performed using ANSYS FLUENT 14.0.

Polybrominated Diphenyl Ethers (PBDEs) Emitted from Heating Machine for Waste Printed Wiring Boards Disassembling

Polybrominated diphenyl ethers (PBDEs) contained in waste printed wiring board (PWB) matrix and surface dust can be emitted into the air during thermal process, which is widely used to detach the electronic components from the base boards of waste PWB. In this study, PBDEs concentrations in air and dust samples were detected in a PWB-heating workshop. The results showed that the mean concentrations of ∑8PBDEs in PM10 and TSP were 479 and 1670 ng/m3, respectively. Compared with surface dust collected from waste PWB (15600 ng/g), PBDEs concentrations in dust from the workshop floor (31100 ng/g), heating machine inside (84700 ng/g), and the cyclone extractor (317000 ng/g), were condensed after thermal process. All the results showed that recycling of waste PWB was an important source of PBDEs emission.

Silver nanoparticle ink technology: state of the art.

Printed electronics will bring to the consumer level great breakthroughs and unique products in the near future, shifting the usual paradigm of electronic devices and circuit boards from hard boxes and rigid sheets into flexible thin layers and bringing disposable electronics, smart tags, and so on. The most promising tool to achieve the target depends upon the availability of nanotechnology-based functional inks. A certain delay in the innovation-transfer process to the market is now being observed. Nevertheless, the most widely diffused product, settled technology, and the highest sales volumes are related to the silver nanoparticle-based ink market, representing the best example of commercial nanotechnology today. This is a compact review on synthesis routes, main properties, and practical applications.

3D Printing of High Voltage Printed Wiring Boards

In the last decade, research has focused on 3D printing for not only creating conceptual models but functional end-use products as well. As patents for 3D printing expire, new low cost desktop systems are being adopted more widely. This trend is leading to products being fabricated locally and improving supply chain logistics. However, currently low cost 3D printing is limited in the number of materials used simultaneously in fabrication and consequently is confined to fabricating enclosures and conceptual models. For additively manufactured end-use products to be useful, supplementary features and functionalities will need to be incorporated in to the final structures in terms of electronic, electromechanical, electromagnetic, thermodynamic, and optical content. The University of Texas at El Paso has recently been reporting on embedding electronic components and electrical interconnect into 3D printed structures either by interrupting the process or by inserting the additional content after the structure has been built. However, only until recently and with an investment from the presidential initiative on Additive Manufacturing “America Makes” has there been a concentrated research focus on developing technology that produces multi-functionality. This presentation will describe a project in which copper wires were used to supply a short burst of energy at high voltages in order to activate electro-propulsion. Pulsed Plasma Thursters provided by Busek were demonstrated where one joule of energy was supplied at 2000 volts in order to ablate the thruster in a vacuum and provide precise micro-newton-levels of force - as required for attitude control in small and nano satellites.

ELECTRONIC CIRCUIT BOARDS NON-UNIFORM COOLING SYSTEM MODEL

Abstract. The paper considers a mathematical model of non-uniform cooling of electronic circuit boards. The block diagram of the system implementing this approach, the method of calculation of the electronic board temperature field, as well as the principle of its thermal performance optimizing are presented. In the considered scheme the main heat elimination from electronic board is produced by the radiator system, and additional cooling of the most temperature-sensitive components is produced by thermoelectric batteries. Are given the two-dimensional temperature fields of the electronic board during its uniform and non-uniform cooling, is carried out their comparison. As follows from the calculations results, when using a uniform overall cooling of electronic unit there is a waste of energy for the cooling 0f electronic board parts which temperature is within acceptable temperature range without the cooling system. This approach leads to the increase in the cooling capacity of used thermoelectric batteries in comparison with the desired values. This largely reduces the efficiency of heat elimination system. The use for electronic boards cooling of non-uniform local heat elimination removes this disadvantage. The obtained dependences show that in this case, the energy required to create a given temperature is smaller than when using a common uniform cooling. In this approach the temperature field of the electronic board is more uniform and the cooling is more efficient.

Developments for Copper-Graphite Composite Thermal Cores for PCBs for High-Reliability and High-Temperature RF Systems

Summary System designs that have only conduction cooling available, that must operate in harsh or challenging environments, present significant challenges to the system thermal engineer. A second thermal design challenge is continued miniaturization of semiconductor devices and increased functionality per square centimeter of semiconductor die, resulting in continued increases in device heat flux. Elimination of packaging materials allows more efficient heat transfer as thermal resistances from one material to another are reduced or designed out. When possible, concurrent elimination of package materials that have low bulk thermal conductivity and replacement with high thermal conductivity materials will improve heat transfer efficiency. Attachment of the resulting unpackaged semiconductor device can then be made directly to the circuit carrier; however, care must be taken regarding increases in potential for damage or failure due to mismatched coefficient of thermal expansion (CTE). Continuing reductions in die size that result in higher heat flux exacerbate this potential failure mechanism at the die-to-substrate level. This is further worsened in harsh environment (i.e., vibration, shock, high moisture, rapid power cycling) and/or high operating temperature conditions. For aerospace, military, geothermal, and other applications where increasingly high heat flux radio frequency (RF), microwave, and processor semiconductors are attached directly (with solders, silver sintering pastes, or other joining materials) to an organic or ceramic printed circuit card, efficient and rapid heat transfer becomes critical. These are frequently also applications where forced convection (air or liquid) may be unavailable to the system design engineer. One solution for thermal management design problems of this type has traditionally been the incorporation of one or more heavy copper layers within a complex multilayer printed circuit board (PCB). This solution, however, has come under increasing scrutiny in recent years due to concerns for weight (especially in airborne and space applications) and the potential for severe CTE mismatch between semiconductor die materials with relatively low thermal expansion values and the relatively very high value of copper. Therefore, development of CTE-matched alternative materials to replace a heavy copper layer has been a focus for development activities. A suitable selection must, however, have a bulk thermal conductivity that is as close to that of copper as is practicable. Recent developments of a copper-graphite composite material in sheet form that can be employed in standardized PCB manufacturing processes are described in this presentation.

A secure NFC mobile payment protocol based on biometrics with formal verification

In this paper, we propose a secure NFC mobile payment protocol based on biometrics SNMPBs using wireless public key infrastructure WPKI and universal integrated circuit card UICC. Electronic signatures generated in this protocol are considered qualified signatures as they are generated in UICC which is tamper resistant device. A procedure for the personalisation of mobile payment application on the UICC by the issuer/bank is proposed. Our SNMPB resolves disputes efficiently among stakeholders by collecting evidence using transaction counters, transaction log, forensics mode and cryptographic audit log techniques. SNMPB ensures end-to-end security i.e., from mobile payments application in UICC to the bank server thereby achieving confidentiality, authentication, integrity and non-repudiation properties, prevents double spending and over spending. Our proposed SNMPB protocol withstands replay, man in the middle MITM, impersonation and multi-protocol attacks as SNMPB is formally verified successfully using BAN logic and Scyther tool.

Basic analysis of starch products for open cooker method (Processed starch for glass cloth production for PC board)

Basic analysis of starch products for open cooker method (Processed starch for glass cloth production for PC board)

C-08 弾丸プロテクトボード評価のためのエアガン開発とPC板の貫通評価

C-08 弾丸プロテクトボード評価のためのエアガン開発とPC板の貫通評価