Analysis Of Printed Circuit Boards Research Articles

A novel calibration method for portable X-ray fluorescence analysis of printed circuit boards.

Printed circuit boards (PCBs) are the most complex and valuable component of electronic devices, but only 34% of them are recycled in an environmentally sound manner. Improving the recycling rate and efficiency requires a fast, reliable and uncostly analytical method. Although the X-ray fluorescence (XRF) shows high potential, it is often unreliable. In this study, we propose a novel XRF methodology for the elemental analysis of PCBs, using the certified reference material (CRM) to decrease uncertainty and enhance accuracy. The results show significant improvement in robustness and accuracy of portable XRF(pXRF) analyses for elements Cu, Pb, Ni, As and Au, with a relative average inaccuracy of approximately 5% compared to referenced values. The methodology validation carried out by comparing pXRF and inductively coupled plasma mass spectroscopy analyses of personal computer motherboard samples shows no statistically significant difference for elements Cu, Cr and Ag. The study shows that the calibration of pXRF by CRMs enables the necessary analysis of PCBs in an efficient and reliable manner and could be also be applied to different types of PCBs and other electronic components, batteries or contaminated soil samples.

Failure Mode and Effects Analysis of PCB for Quality Control Process

The aim of this study is to highlight the key elements for optimizing printed circuit board (PCB) fabrication productivity through improving manufacturing process efficiency. Failure mode and effect analysis (FMEA) is a technique used to reduce the percentage of finished goods that are found to be defective during the manufacturing process and final inspection, resulting in low rejection ratios and optimized PCB design. This paper presents all the quality steps to achieve high efficiency in PCB design. The study is done in electronics manufacturing industry in which its production begins from receiving PCBs, raw material then bringing them into punching and assembly processes through surface mount machines (SMT). To find defective items and lower the possibility of defective final products, or IPQC (in-process quality control), is used. The average of customer manufacturers lot reject rate (%LRR of CMs) has been improved by using improved quality control. For assessing the risk connected to probable issues discovered during a failure mode and effects analysis, the risk priority number (RPN) methodology technique is applied. The FMEA RPN assists the responsible team or individual in prioritizing risks and choosing the appropriate remedial measures. Lot reject rate (LRR) improved by FMEA is from 5500 parts per million (PPM) to 900 parts per million (PPM), and faults have decreased by 0.76% as a result of improved quality control.

Electromagnetic Compatibility Analysis and Optimization Design of Switching Power Supply Printed Circuit Board

Printed Circuit Board (PCB) is not only an important electrical module of information equipment, but also an important source of electromagnetic radiation. Only when PCB works normally and is compatible with other electrical equipment, the whole information equipment can work normally. Because of the complexity of PCB structure and the difficulty of modeling, the EMC (Electromagnetic Compatibility) analysis of PCB is very difficult. For this reason, Taking the widely used full bridge current double rectifier converter as an example, aiming at the electromagnetic compatibility problems caused by the PCB design of the switching power supply, this paper proposes a simulation method based on the electromagnetic field by establishing the near-field radiation model of the PCB, analyzes the areas with high radiation intensity in the PCB layout, by optimizing the layout and wiring of the PCB, the electromagnetic compatibility performance of the switching power supply is improved. The simulation results show that the near-field radiation characteristics of PCB can be predicted by introducing the electromagnetic field simulation method in the design stage, according to the characteristics of the magnetic field, the optimal design is realized, so that the EMC of the switching power supply reaches the standard, and finally the working performance of the switching power supply is improved.

Modeling flexible/curved PCBs using RBF mesh morphing

In the recent past, flexible printed circuit board (PCB) electronics have seen a significant surge in many electronics products ranging from smartphone/watches that wrap around our wrists, displays that fold out as large television sets, reconfigurable electronics that conform to the roofs/trunks of cars or as flexible implants that can monitor and treat diseases. Whatever the need is, it is quite evident that the near future is bound to see a significant uptick in day-to-day usage of such electronic products and hence as a direct result there is a need for numerical modeling, simulation and analysis of PCB’s that conform to different shapes. However, given the complexity of PCB’s, numerical modeling of such structures remains a challenge and there is a need for a clear and simple methodology to accomplish this. In addition, the developed methodology should also be applicable to both the trace mapping and trace modeling techniques typically used while working with Electronic-CAD files. In this work, the RBF (Radial Basis Function) method has been presented as a capable technology that can morph the flat mesh electronic data to a curved space which can be further used for analysis purposes. Since the morphing is being directly implemented at the mesh level, a lot of obstacles and complexity typically encountered while generating curved PCB CAD files can be avoided. The RBF Morph ACT Extension has been the tool of choice in the current context. This extension was built on the modular architecture of the ANSYS Workbench and is hence deeply integrated into Mechanical which makes it easy to work with. While RBF Morph offers a wide range of morphing capabilities, a 2-step morph process which relies on an auxiliary body and 2D coordinate filtering technique has been identified as most reliable technique of choice for most curved geometries. The morph technique developed has been successfully applied to a wide range of curved structures which include solid PCBs as well.

Design and Analysis of a Rectangular PCB Printed Magnetorquer for Nanosatellites

CubeSats have become increasingly important in the last two decades and are playing a very important role in the space industry, especially with Earth-oriented nanosatellites. Earth-oriented nanosatellites require more precise attitude control when there is a requirement for good pointing accuracy. In such missions, passive control systems are not suitable due to their low accuracy, hence, active control systems are used. Different types of actuators are available, but magnetic actuators are best suited for low-Earth orbit (LEO) nanosatellites. When current moves through the wire, a magnetic field is generated which is used to generate torque. The torque generated makes it possible to control the attitude of the satellite in the desired direction. The best option for nanosatellites is to use the printed or embedded magnetorquers due to its scalable, reconfigurable, and modular approach. Printing the magnetorquer into the internal layers of the printed circuit board (PCB) reduce the harness complexities and space constraints effectively. The optimized design of the printed magnetorquer is selected by analyzing various parameters, such as turn width, distance between two turns, applied voltage, external dimensions, and internal dimensions. The design also takes into consideration other parameters, such as generated torque, torque-to-power ratio, magnetic field to current ratio, consumed power, rotation time, and thermal analysis, by changing the optimizing variables and taking into account the most important key design drivers. The design selection and results of the analysis concerning the selection of optimized parameters are presented.

Modal finite element analysis of PCBs and the role of material anisotropy

Printed Circuit Boards (PCBs) are epoxy resin-impregnated and cured sheets of counter woven glass fabric (e.g. FR4) laminated between thin sheets of Copper. The nature of the PCB is inherently anisotropic and inhomogeneous but previous modal FEMs of PCBs have assumed isotropic, anisotropic (transversely isotropic and orthotropic) material properties and shown good correlation with test data for specific scenarios [1-3]. This paper details part of a research program aimed at gaining a better understanding of accurately modeling PCB’s dynamic behavior. New investigations into the impact of material anisotropy and, in particular, the effect of material orthogonal plane definition (Ex and Ey) on eigenfrequencies is analysed. A modal FEM of a JEDEC PCB is created, verified, and validated using well established theories by Steinberg and empirical data by others [4, 5]. The relative contributions of Ex, Ey and Ez on PCB eigenfrequencies is examined using a parametric modal FEM, analysing the role of material isotropy verses anisotropy. The impact of transversely isotropic material properties is also analysed for a typical JEDEC PCB. This analysis details the mesh density required for accurately modeling the PCB eigenfrequencies. The results show that a 100 % increase in Ez has only a 0.2 % difference in the eigenfrequency where as a 100 % increase in Ey has a 1.2 % difference in the eigenfrequency. The effect of orthotropic plane definition (alternating Ex with Ey) on the JEDEC PCB amount to a 7.95 % delta in eigenfrequency.

Multi-element chemical analysis of printed circuit boards – challenges and pitfalls

Printed circuit boards (PCB) are an essential component of electrical and electronic equipment (EEE) and account for roughly 5% of the mass of EEE. Knowledge about the chemical composition of PCB is crucial to enable an enhanced recycling, especially for elements considered critical regarding their economic importance and supply risk (e.g. precious metals or specialty metals such as tantalum, germanium, gallium). No standard reference methods exist for determining the chemical composition of PCB. Previously published element mass fractions cover a wide range and were produced with numerous methods for sample preparation, digestion, and measurement. This impedes comparability of PCB composition from different studies. To investigate sample- and element-specific effects of applied methods a PCB sample from desktop PC was analysed in two separate labs. One lab applied sample- and element-specific validated methods (aqua regia, HF, H2SO4 blend; ICP-OES, QQQ-ICP-MS), providing reference values, the other applied routine in-house methods (aqua regia; ICP-OES, ICP-MS) to assess the validity of in-house methods for chemical analysis of PCB. A t-test was used to identify elements depicting significant differences between validated and in-house methods. For base metals, in-house methods led to comparable results. For precious, specialty, and hazardous metals as well as REE investigated in this study, significant differences were detected. With respect to all results for in-house methods in this study, the combination of aqua regia and ICP-OES led to less significant differences than aqua regia and ICP-MS. The results show that sample- and element-specific quality assurance is crucial to prevent analytical bias.

Analysis of High-Speed PCB With SiC Devices by Investigating Turn-Off Overvoltage and Interconnection Inductance Influence

Silicon (Si) carbide (SiC)-based power switching devices provide significant performance improvements compared to conventional Si devices. The superior characteristics enable considerable loss, size, and weight reduction of power converters in the powertrain of hybrid/electric vehicles. However, the fast switching capability of SiC devices renders them more vulnerable to parasitic inductances in the circuit. The purpose of this paper is to analyze the impact of interconnection inductances to overvoltage during turn-OFF transient of SiC devices. To understand the switching behavior of the SiC devices, the ringing and overshoots of the voltage caused by the device capacitance and interconnection inductances are considered. Parametric studies are conducted to compare the influences of printed circuit board (PCB) and packaging inductances on the peak turn-OFF overvoltage under various operating conditions. A prototype half-bridge buck converter with SiC MOSFETs is constructed for the experiments. Experimental results are shown to validate the simulation results.

Correlation analysis of PCB and comparison of test-analysis model reduction methods

The validity of correlation analysis between finite element model (FEM) and modal test data is strongly affected by three factors, i.e., quality of excitation and measurement points in modal test, FEM reduction methods, and correlation check techniques. A new criterion based on modified mode participation (MMP) for choosing the best excitation point is presented. Comparison between this new criterion and mode participation (MP) criterion is made by using Case 1 with a simple printed circuit board (PCB). The result indicates that this new criterion produces better results. In Case 2, 35 measurement points are selected to perform modal test and correlation analysis while 9 selected in Case 3. System equivalent reduction expansion process (SEREP), modal assurance criteria (MAC), coordinate modal assurance criteria (CoMAC), pseudo orthogonality check (POC) and coordinate orthogonality check (CORTHOG) are used to show the error introduced by modal test in Cases 2 and 3. Case 2 shows that additional errors which cannot be identified by using CoMAC can be found by using CORTHOG. In both Cases 2 and 3, Guyan reduction, improved reduced system (IRS) method, SEREP and Hybrid reduction are compared for accuracy and robustness. The results suggest that the quality of the reduction process is problem dependent. However, the IRS method is an improvement over the Guyan reduction, and the Hybrid reduction is an improvement over the SEREP reduction.

Analysis of PCB via for Signal Integrity Using ANOVA

This paper based on ANOVA (ANalysis Of VAriance) presents an investigation in the design of signal via in multilayered printed circuit boards (PCB) technology from a signal integrity point of view. Using the concept of the orthogonal array (OA), different vias physical aspect ratios have been set in the analysis. The impacts of these parameters are investigated with the help for a full-wave electromagnetic simulation soft HFSS. This study demonstrates the factors which is the most influence on the signal integrity.

Reliability Failure Analysis of PCB and its Technological Improvement

Reliability failure analysis is extremely important in the manufacturing process of PCB (Printed Circuit Board). In this paper, we use thermal shock test method to analysis the electrical interconnection reliability of PCB in harsh environment. Also taking into account the reliability of PCB is closely related to its design and technology, approaches of technological improvement are proposed. Finally through temperature shock test method, the results show that the reliability of PCB designed with improved technology is enhanced.

A New ANN-Based Modeling Approach for Rapid EMI/EMC Analysis of PCB and Shielding Enclosures

This paper introduces a new artificial neural networks (ANNs)-based reverse-modeling approach for efficient electromagnetic compatibility (EMC) analysis of printed circuit boards (PCBs) and shielding enclosures. The proposed approach improves the accuracy of conventional or standard neural models by reversing the input-output variables in a systematic manner, while keeping the model structures simple relative to complex knowledge-based ANNs (e.g., KBNNs). The approach facilitates accurate and fast neural network modeling of realistic EMC scenarios where training data are expensive and sparse. To establish accuracy, efficiency, and feasibility of the proposed reverse-modeling approach, PCB structures such as perforated surface-mount shields and partially shielded PCB traces are treated as proof-of-concept examples. Although the modeling examples presented in the paper are based on training data from EM simulations, the approach is generic and hence valid for EMC modeling based on the measurement data. The approach is particularly useful in the electronic manufacturing industry where PCB layouts are frequently reused with minor modifications to the existing time-tested designs.

Calculating Radiated Emissions Due to I/O Line Coupling on Printed Circuit Boards Using the Imbalance Difference Method

High frequency signals on printed circuit board (PCB) traces can couple to I/O nets that carry the coupled energy away from the board resulting in significant radiated emissions. Automated tools to detect unacceptable levels of coupling during the board layout rely on fast methods for estimating the amount of coupling and the resulting radiated emissions. A modeling technique is proposed to speed up the analysis of PCBs with coupled traces that induce common-mode currents on attached cables. Based on the concept of imbalance difference, differential-mode sources are converted to equivalent common-mode sources that drive the attached cable and the PCB reference plane. A closed-form expression based on the imbalance difference model is developed to estimate the maximum radiated emissions due to I/O line coupling in PCBs.

Hybrid $S$-Parameters for Transmission Line Networks With Linear/Nonlinear Load Terminations Subject to Arbitrary Excitations

We propose a generalized S-parameter analysis for transmission lines (TLs) with linear/nonlinear load terminations subject to arbitrary plane-wave and port excitations. S-parameters are prevalently used to model TLs such as cable bundles and interconnects on printed circuit boards (PCBs) subject to port excitations. The conventional S-parameter approach is well suited to characterize interactions among ports. However, nontraditional port excitations associated with plane-wave coupling to physical ports at TL terminals lead to forced, as well as propagating, modal waves, necessitating a modification of the standard S-parameter characterization. In this paper, we consider external plane-wave excitations, as well as port (internal) sources, and propose a hybrid S-parameter matrix for characterization of the associated microwave network and systems. A key aspect of the approach is to treat the forced waves at the ports as constant voltage sources and induced propagating modal waves as additional entries (hybrid S-parameters) in the S-parameter matrix. The resulting hybrid S-matrix and voltage sources can be subsequently exported to any circuit solver such as HSPICE and Agilent's Advanced Design System for the analysis of combined linear and nonlinear circuit terminations at ports. The proposed method is particularly suited for susceptibility analysis of cable bundles and PCBs for electromagnetic interference evaluations. It also exploits numerical techniques for structural and circuit domain characterization and allows for circuit design optimization without a need to perform any further computational electromagnetic analysis

Viscoelastic Influence on Dynamic Properties of PCB Under Drop Impact

Dynamic properties of printed circuit board (PCB) assembly under drop impact are investigated when viscoelasticity of substrate materials is considered. The main materials of a PCB substrate are macromolecule resins, which are typical viscoelastic materials. From the viewpoint of viscoelasticity, the dynamics of PCBs under drop impact is analyzed based on mass-damping-spring, beam, and plate theories. It is demonstrated that the viscoelasticity of a PCB has distinct influences on the dynamic properties of PCBs under board-level drop impact. When there is an increase in the viscosity of substrate materials, the damping coefficients of PCBs would rise, its deflection and acceleration responses could diminish faster, and the maximum deflection of PCBs would become smaller. Meanwhile, with the same viscosity and drop impact conditions, a larger plate would produce a bigger deflection response. Therefore, drop impact reliability could be enhanced by choosing substrate material of larger viscoelasticity and reducing properly the size of PCBs. Dynamic analysis of PCBs under drop impact not only contributes to perfecting theoretical research, but also provides a reference for the choice of substrate materials and reliability design of PCBs when electronic products are devised.

Study of the multilayer PCB CTEs by moiré interferometry

Microelectronics packaging has been developing rapidly due to the demands for faster, lighter and smaller products. Printed circuit boards (PCBs) provide mechanical support and electrical interconnection for electronic devices. Many types of composite PCBs have been developed to meet various needs. Recent trends in reliability analysis of PCBs have involved development of the structural integrity models for predicting lifetime under thermal environmental exposure; however the theoretical models need verification by the experiment. The objective of the current work is the development of an optical system and testing procedure for evaluation of the thermal deformation of PCBs in the wide temperature range. Due to the special requirements of the specimen and test condition, the existing technologies and setups were updated and modified. The discussions on optical methods, thermal loading chambers, and image data processing are presented. The proposed technique and specially designed test bench were employed successfully to measure the thermal deformations of PCB in the −40°C to +160°C temperature range. The video-based moiré interferometry was used for generating, capturing and analysis of the fringe patterns. The obtained information yields the needed coefficients of thermal expansion (CTE) for tested PCBs.

The Cooling Efficiency Concept — A Tool for Fast Thermal Analysis of PCBs

Thermal analyses of printed circuit boards (PCBs) based on the finite element or finite difference methods are frequently used in the electronics industry, the major reason for this being the geometrical complexity of the thermal problems. Correctly used and with access to all relevant data, these methods are very accurate. In the early stages of the PCB design process, it is often necessary to make temperature estimations based on data which are very uncertain and sometimes mere guesswork. Any temperature prediction based on such assumptions will, regardless of the method used, always be of a preliminary nature. A fast and approximate method can then offer advantages over a complex but accurate method. The cooling efficiency for a PCB is defined as the heat dissipation for the PCB over the heat dissipation for a flat smooth isothermal plate of the same size and with a temperature which equals the maximum temperature of the PCB. This definition makes it possible to derive the maximum temperature on a PCB from the well‐defined isothermal case. The cooling efficiency for a particular PCB can be calculated or measured. The experience of the author is that the values for most multilayer PCBs are in the range 50–85%. For PCBs which have a few concentrated heat sources, the cooling efficiency could be considerably lower. For PCBs with any form of surface extension, the cooling efficiency could be higher. The cooling efficiency concept is particularly useful as a fast front‐end thermal analysis tool. The concept can also be used in conjunction with thermal specifications of PCBs and at the PCB enclosure level.