scholarly journals Microorganisms and Plants in the Recovery of Metals from the Printed Circuit Boards of Computers and Cell Phones: A Mini Review

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1120 ◽  
Author(s):  
Rosalba Argumedo-Delira ◽  
María Esther Díaz-Martínez ◽  
Mario Javier Gómez-Martínez
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Cell Phones ◽  
Electronic Equipment ◽  
Circuit Board ◽  
Printed Circuit ◽  
High Metal Content ◽  
Industrial Level ◽  
Biological Methods ◽  
Microelectronic Components

Most electrical and electronic equipment contain a printed circuit board (PCB), which is the board on which microelectronic components are mounted. The PCBs of obsolete and discarded electrical and electronic equipment are a material of great value due to their high metal content that is of commercial importance (i.e., Au, Ag, Pd, Pt, Ir, Ti, Ge, Si, Al, Cu, Ni, Zn, Fe, Sn, As, and Pb). Hydrometallurgical and pyrometallurgical methods have been used to extract metals from PCBs; however, these methods have energy and environmental disadvantages, which is why in recent years sustainable alternatives have been sought. Among these alternatives are the biological methods that contemplate the use of microorganisms and plants to recover metals from PCBs. In this review, only studies specifying the use of bacteria, fungi, and plants in the recovery of metals from the PCBs of computers and cell phones were considered, since the metallic composition of these plates varies according to the electronic equipment. In addition, the challenges and recommendations for these biotechnological processes to be improved and implemented at the industrial level in the coming years are discussed.

scholarly journals Estimating Recycling Return of Integrated Circuits Using Computer Vision on Printed Circuit Boards

2021 ◽  
Vol 11 (6) ◽  
pp. 2808
Author(s):  
Leandro H. de S. Silva ◽  
Agostinho A. F. Júnior ◽  
George O. A. Azevedo ◽  
Sergio C. Oliveira ◽  
Bruno J. T. Fernandes
Keyword(s):  
Integrated Circuits ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Electronic Waste ◽  
Decision Criterion ◽  
Economic Feasibility ◽  
Electronic Equipment ◽  
Circuit Board ◽  
Mechanical Recycling ◽  
Printed Circuit

The technological growth of the last decades has brought many improvements in daily life, but also concerns on how to deal with electronic waste. Electrical and electronic equipment waste is the fastest-growing rate in the industrialized world. One of the elements of electronic equipment is the printed circuit board (PCB) and almost every electronic equipment has a PCB inside it. While waste PCB (WPCB) recycling may result in the recovery of potentially precious materials and the reuse of some components, it is a challenging task because its composition diversity requires a cautious pre-processing stage to achieve optimal recycling outcomes. Our research focused on proposing a method to evaluate the economic feasibility of recycling integrated circuits (ICs) from WPCB. The proposed method can help decide whether to dismantle a separate WPCB before the physical or mechanical recycling process and consists of estimating the IC area from a WPCB, calculating the IC’s weight using surface density, and estimating how much metal can be recovered by recycling those ICs. To estimate the IC area in a WPCB, we used a state-of-the-art object detection deep learning model (YOLO) and the PCB DSLR image dataset to detect the WPCB’s ICs. Regarding IC detection, the best result was obtained with the partitioned analysis of each image through a sliding window, thus creating new images of smaller dimensions, reaching 86.77% mAP. As a final result, we estimate that the Deep PCB Dataset has a total of 1079.18 g of ICs, from which it would be possible to recover at least 909.94 g of metals and silicon elements from all WPCBs’ ICs. Since there is a high variability in the compositions of WPCBs, it is possible to calculate the gross income for each WPCB and use it as a decision criterion for the type of pre-processing.

PROCESS IMPACTS ON RELIABILITY OF PRINTED CIRCUIT BOARDS

2018 ◽  
pp. 6-9
Author(s):  
O. A. Korotky ◽  
A. A. Korneev ◽  
A. Yu. Galkin
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Electronic Equipment ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Warranty Period ◽  
Complex Technical Systems ◽  
The Military

The paper considers defects that directly affect the quality of the finished product, which includes printed circuit boards and wiring connections. Current problems lead to failures of electronic equipment, which can lead to the failure of complex technical systems with subsequent downtime. Also methods for increasing the reliability of electronic equipment products are proposed, which exclude premature failures of the equipment as a whole. Such failures include breakage of the metallization column during extreme heating of the printed circuit board, poor connection quality of components on the board, absence of a layer between the component and the board. The method of preventing such problems is presented below in the text. Elimination of the above defects can lead to trouble-free operation throughout the warranty period of operation of the equipment at various facilities, including those in the military.

scholarly journals Direct Chip Mounting — A Challenge to the Design Engineer

1982 ◽  
Vol 10 (1) ◽  
pp. 1-6
Author(s):  
J. Lorman ◽  
J. Prochaska
Keyword(s):  
Degrees Of Freedom ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Basic Element ◽  
Electronic Equipment ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
High Degree ◽  
Good Possibility

The extrapolation of development trends in the area of technologically complicated electronic equipment shows an ever increasing complexity in semiconductor technology. This development has so concerned the constructors of electronic equipment that progress in the technology of mounting and interconnection has taken a secondary place.This growing divergence between a fast developing microelectronic industry, and a conservative state of the macroelectronics industry, is a driving force with regard to the progress to effective connection technologies at every level of mounting. The technological solution to all systems will then become more coordinated.The mounting of components to printed circuit boards is traditionally a soldering operation. This principle lead to the development of full automation, and is a standard mounting technology. The growth of integration at the chip level has however brought new requirements that are only satisfied with difficulty.Newly developed requirements show that the use of dual-in-line packages will be unsatisfactory. New methods must be designed to connect the chips directly to the printed circuit board, going from the chip as the smallest mounted unit.Requirements for very complex electronic equipment with a high degree of integration (LSI or VLSI) are not satisfied using traditional mounting systems. These require a totally new mounting concept, from the chips to the printed circuit board.In this paper alternatives to printed circuit board technology with insulated wiring (multilayers), and the mounting of chips from film carriers, are evaluated. These principles have a good possibility of further improvement as progress in mounting technology continues.Price reductions cause an extension of application possibilities and an extension of electronic designs. It is harder to make choices for new designs when there are more degrees of freedom. However the function of chips as the basic element is unchangeable and optimum designs need to be based on this concept.

Dielectric Breakdown in Printed Circuit Boards at Elevated Temperatures

1996 ◽  
Author(s):  
P. Singh ◽  
G.T. Galyon ◽  
J. Obrzut ◽  
W.A. Alpaugh
Keyword(s):  
Experimental Data ◽  
Thermal Degradation ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Elevated Temperatures ◽  
Dielectric Breakdown ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Data Matching

Abstract A time delayed dielectric breakdown in printed circuit boards, operating at temperatures below the epoxy resin insulation thermo-electrical limits, is reported. The safe temperature-voltage operating regime was estimated and related to the glass-rubber transition (To) of printed circuit board dielectric. The TG was measured using DSC and compared with that determined from electrical conductivity of the laminate in the glassy and rubbery state. A failure model was developed and fitted to the experimental data matching a localized thermal degradation of the dielectric and time dependency. The model is based on localized heating of an insulation resistance defect that under certain voltage bias can exceed the TG, thus, initiating thermal degradation of the resin. The model agrees well with the experimental data and indicates that the failure rate and truncation time beyond which the probability of failure becomes insignificant, decreases with increasing glass-rubber transition temperature.

Evaluation of new technologies and materials for printed circuit boards with improved heat dissipation properties

Circuit World ◽  
2016 ◽  
Vol 42 (1) ◽  
pp. 32-36 ◽  
Author(s):  
Michal Baszynski ◽  
Edward Ramotowski ◽  
Dariusz Ostaszewski ◽  
Tomasz Klej ◽  
Mariusz Wojcik ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Printed Circuit Boards ◽  
Heat Dissipation ◽  
Printed Circuit Board ◽  
New Technologies ◽  
Electronic Device ◽  
Circuit Board ◽  
New Materials ◽  
Content Type ◽  
Printed Circuit

Purpose – The purpose of this paper is to evaluate thermal properties of printed circuit board (PCB) made with use of new materials and technologies. Design/methodology/approach – Four PCBs with the same layout but made with use of different materials and technologies have been investigated using thermal camera to compare their thermal properties. Findings – The results show how important the thermal properties of PCBs are for providing effective heat dissipation, and how a simple alteration to the design can help to improve the thermal performance of electronic device. Proper layout, new materials and technologies of PCB manufacturing can significantly reduce the temperature of electronic components resulting in higher reliability of electronic and power electronic devices. Originality/value – This paper shows the advantages of new technologies and materials in PCB thermal management.

scholarly journals A Study on the Radiated Susceptibility of Printed Circuit Boards and the Effects of Via Fencing

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 539
Author(s):  
Ryan P. Tortorich ◽  
William Morell ◽  
Elizabeth Reiner ◽  
William Bouillon ◽  
Jin-Woo Choi
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Ground Plane ◽  
Circuit Board ◽  
Electronic Systems ◽  
Coupling Mechanism ◽  
Electromagnetic Modeling ◽  
Printed Circuit ◽  
Edge Radiation ◽  
Area Of Concern

Because modern electronic systems are likely to be exposed to high intensity radiated fields (HIRF) environments, there is growing interest in understanding how electronic systems are affected by such environments. Backdoor coupling in particular is an area of concern for all electronics, but there is limited understanding about the mechanisms behind backdoor coupling. In this work, we present a study on printed circuit board (PCB) backdoor coupling and the effects of via fencing. Existing work focuses on ideal stackups and indicates that edge radiation is significantly reduced by via fencing. In this study, both full wave electromagnetic modeling and experimental verification are used to investigate both ideal and practical PCB stackups. In the ideal scenario, we find that via fencing substantially reduces coupling, which is consistent with prior work on emissions. In the practical scenario, we incorporate component footprints and traces which naturally introduce openings in the top ground plane. Both simulation and experimental data indicate that via fencing in the practical scenario does not substantially mitigate coupling, suggesting that PCB edge coupling is not the dominant coupling mechanism, even at varying angles of incidence and polarization.

Hierarchical pyramidal subsampling in deep convolutional networks for visual pattern recognition

2021 ◽  
Author(s):  
A. E. Averyanikhin ◽  
A. I. Vlasov ◽  
E. V. Evdokimova
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Flaw Detection ◽  
Input Image ◽  
Circuit Board ◽  
Digital Data ◽  
Deep Convolutional Neural Networks ◽  
Size Scale ◽  
Printed Circuit ◽  
Convolutional Networks

The main problem of known deep convolutional neural networks (CNN) is that they require a fixed-size input image. This requirement is “artificial” and can reduce recognition accuracy for images or its parts of arbitrary size/scale. The paper proposes a strategy of combining “hierarchical pyramidal subselection” to eliminate the above restriction. The structure of the neural network using the proposed combining strategy allows the generation of prediction regardless of the size/scale of the original image, and also improves the accuracy of recognition. Features of application of CNN for identification and recognition of defects of conducting pattern of printed circuit board blanks have been considered. Features of defects of conductive pattern of printed circuit board blanks have been briefly discussed. The invention proposes the use of artificial CNN, which have advantages in speed and accuracy in solving problems of object recognition on images relative to existing methods. The focus is on the architecture of CNN using hierarchical pyramidal subselection. Capabilities of application of CNN for recognition of defects of conducting pattern of printed circuit board blanks have been shown. Proposed method of hierarchical pyramidal subselection in deep convolutional networks has been implemented in software complex, which allows processing digital data of photographs of conducting pattern of printed circuit boards, in particular during their flaw detection, and can be used for localization of existing defects of conducting pattern. The conclusion draws the possibilities of using methods and means of image processing in flaw detection of radio-electronic equipment and instruments

scholarly journals Optimization Studies on Recovery of Metals from Printed Circuit Board Waste

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
P. Sivakumar ◽  
D. Prabhakaran ◽  
M. Thirumarimurugan
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Lead Nitrate ◽  
Acid Leaching ◽  
Circuit Board ◽  
Copper Recovery ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Electrode Combination ◽  
Lead Metal

The aim of the study was to recover copper and lead metal from waste printed circuit boards (PCBs). The electrowinning method is found to be an effective recycling process to recover copper and lead metal from printed circuit board wastes. In order to simplify the process with affordable equipment, a simple ammonical leaching operation method was adopted. The selected PCBs were incinerated into fine ash powder at 500°C for 1 hour in the pyrolysis reactor. Then, the fine ash powder was subjected to acid-leaching process to recover the metals with varying conditions like acid-base concentration, electrode combination, and leaching time. The relative electrolysis solution of 0.1 M lead nitrate for lead and 0.1 M copper sulphate for copper was used to extract metals from PCBs at room temperature. The amount of lead and copper extracted from the process was determined by an atomic absorption spectrophotometer, and results found were 73.29% and 82.17%, respectively. Further, the optimum conditions for the recovery of metals were determined by using RSM software. The results showed that the percentage of lead and copper recovery were 78.25% and 89.1% should be 4 hrs 10 A/dm2.

scholarly journals A model for the reflection of terahertz signals from printed circuit board surfaces

2018 ◽  
Vol 10 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Alexander Fricke ◽  
Mounir Achir ◽  
Philippe Le Bars ◽  
Thomas Kürner
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Simulated Annealing Algorithm ◽  
Specular Reflection ◽  
Circuit Board ◽  
Network Analyzer ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Propagation Modeling ◽  
Annealing Algorithm

AbstractBased on vector network analyzer Measurements, a model for the specular reflection behavior of printed circuit boards in the Terahertz range has been derived. It has been calibrated to suit the behavior of the measurements using a simulated annealing algorithm. The model has been tailored for integration to ray-tracing-based propagation modeling.

scholarly journals NotchPUF: Printed Circuit Board PUF Based on Microstrip Notch Filter

Cryptography ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 11
Author(s):  
Mitchell Martin ◽  
Jim Plusquellic
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Statistical Tests ◽  
Notch Filter ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
In Series ◽  
Commercial Off The Shelf ◽  
Using Data

Physical Unclonable Functions (PUFs) are primitives that are designed to leverage naturally occurring variations to produce a random bitstring. Current PUF designs are typically implemented in silicon or utilize variations found in commercial off-the-shelf (COTS) parts. Because of this, existing designs are insufficient for the authentication of Printed Circuit Boards (PCBs). In this paper, we propose a novel PUF design that leverages board variations in a manufactured PCB to generate unique and stable IDs for each PCB. In particular, a single copper trace is used as a source of randomness for bitstring generation. The trace connects three notch filter structures in series, each of which is designed to reject specific but separate frequencies. The bitstrings generated using data measured from a set of PCBs are analyzed using statistical tests to illustrate that high levels of uniqueness and randomness are achievable.

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