Copper Recovery from Printed Circuit Boards Waste Sludge: Multi-step Current Electrolysis and Modeling

This paper embodies Data Transformation System for PCB (Printed Circuit Board) production automation. Data designed by CAD cannot be compatible with data of PCB production line, so it should have a data compatible automated system. This paper has been developed a human error extraction algorithm for PCB production automation and an algorithm that transforms reliable data for PCB production line and also an interface for this. As the result, processing rate has been improved and it helps PCB production automation with reliable optimized data.

Ultrasonic recovery of copper and iron through the simultaneous utilization of Printed Circuit Boards (PCB) spent acid etching solution and PCB waste sludge

PurposeToday a large variety of printed circuit board (PCB) base materials exists on the market and new ones are added frequently. The base material suppliers, having good original equipment manufacturer (OEM) marketing, usually present the materials in an early development stage to the end customers. The customers, on the other hand, expect from their PCB suppliers that the materials are fully characterized and that qualification samples are available immediately. In many cases, the process recommendations given to the PCB manufacturers are very generic (“like FR4”), insufficient, or not practicable (“8 hours baking time”). However, optimized processing ensures the reliability of the finished PCBs, starting from general leadfree compatibility to CAF testing. This demonstrates the importance of thoroughly verified process parameters and of very specific process recommendations to minimize the number of costly and time‐consuming iterations, and to be able to meet the goal of submitting qualification samples and functional PCBs in minimum time. The purpose of this paper is to show the minimum required PCB processing recommendations, and why these have to be fixed by the material supplier before commercialization of a new base material.Design/methodology/approachThe paper examines the base material suppliers' situation, customer expectations and reality and the PCB manufacturers' expectations.FindingsThe paper gives the reasons and consequences of early base material marketing.Originality/valueThe paper analyses today's PCB base materials market and shows the reasons and consequences of early base material marketing. Also, the minimum requirements by PCB fabricators concerning processing recommendations are given.

Due to the rapid development of printed circuit board (PCB) industry during the 1990s and 2000s, China has become the largest PCB manufacturing country in the world. However, in terms of advanced PCB products on behalf of industry and technology trends, for example high density interconnect (HDI) and flexible printed circuit (FPC) boards, Chinese PCB manufacturers still lag behind both in technical level and production capacity, compared with America, Japan, etc. Therefore, in recent years Chinese universities, institutes and PCB manufacturers have conducted much basic research on high-end PCB technology, including how to improve the performance of PCB. In this paper, a concise survey about the development of China PCB industry is given at first, followed by technical problems that China has to overcome to continue her leadership in PCB industry. Then, some typical basic research results achieved in recent years in China towards solving the technical challenges are introduced. The research results include methods of analysis and solution of the signal/power integrity (SI/PI) and electromagnetic compatibility (EMC) problems, and approaches of electro-thermal modeling, analysis and co-design, all for performance enhancement or improvement of PCB. At last, some discussion about the future research program and activities in China is presented.

The objective of this study is to investigate the environmental impacts of a printed circuit board (PCB) manufacturing plant through streamlined life cycle assessment approach. As a result, the most effective recommendations on minimizing the environmental impacts for the mentioned sector are revealed and first steps towards establishing a country specific database are taken. The whole PCB production consists of two consecutive stages: namely board fabrication followed by the manufacturing of PCB. Manufacturing of PCB contributes the highest shares to freshwater aquatic ecotoxicity potential (FAETP) and ozone layer depletion potential (ODP). Eighty-nine percent of FAETP is found to be generated from the manufacturing of PCB. Almost all of this contribution can be attributed to the disposal of copper containing wastewater treatment sludge from etching operations to incineration. On the other hand, PCB manufacturing has 73% share in total ODP. Within the manufacturing of PCB, as etching operations are found to be of importance for all the impact categories except eutrophication potential (EP), it is recommended to focus further studies on in-plant control of etching.

One of the essential requirements for handheld devices such as smart phone, digital camer, and note-PC is the slim design to satisfy the customers' desires. PCB (Printed Circuit Board) should be also thinner for slim appearance. However, the PCB bending stiffness decreases as the PCB becomes thinner, which is one of the most difficult concerns to engineers. Especially, PCB deforms severely during reflow (soldering) process where the peak temperature goes up to 250°C. Therefore, it is necessary for thermo-mechanical quality/reliability engineers to predict PCB deformation at high temperature before PCB manufacturing. The purpose of this paper is to predict PBA (Printed Board Assembly) deformation based on thermo-mechanical finite element analysis by using the following capabilities. First, PCB is modelled in detail in order to obtain the interlayer stress caused by CTE or elastic modulus mismatch between each layer. Also, the contact boundary condition between PCB and rails in the reflower is considered because PCB deformation along the rails cannot be predicted in advance. Last, PCB multiple array placement can be controlled by the user to find the optimized PCB array for minimum PCB warpage. From the numerical results, it is seen that thermo-mechanical analyses of PBA based on detailed modeling can give the engineer PCB warpage prediction.

Printed circuit boards (PCBs) are primarily used to connect electronic components to each other. It is one of the most important stages in the manufacturing of electronic products. A small defect in the PCB can make the final product inoperable. Therefore, careful and meticulous defect detection steps are necessary and indispensable in the PCB manufacturing process. The detection methods can generally be divided into manual inspection and automatic optical inspection (AOI). The main disadvantage of manual detection is that the detection speed is too slow, resulting in a waste of human resources and costs. Thus, in order to speed up the production speed, AOI techniques have been adopted by many PCB manufacturers. Most current AOI mechanisms use traditional optical algorithms. These algorithms can easily lead to misjudgments due to different light and shadow changes caused by slight differences in PCB placement or solder amount so that qualified PCBs are judged as defective products, which is also the main reason for the high misjudgment rate of AOI detection. In order to effectively solve the problem of AOI misjudgment, manual re-judgment is currently the reinspection method adopted by most PCB manufacturers for defective products judged by AOI. Undoubtedly, the need for inspectors is another kind of labor cost. To reduce the labor cost. of manual re-judgement, an accurate and efficient PCB defect reinspection mechanism based on deep learning algorithm is proposed. This mechanism mainly establishes two detection models, which can classify the defects of the product. When both models have basic recognition capabilities, the two models are then combined into a main model to improve the accuracy of defect detection. In the study, the data provided by Lite-On Technology Co., Ltd. were implemented. To achieve the practical application value in the industry, this research not only considers the problem of detection accuracy, but also considers the problem of detection execution speed. Therefore, fewer parameters are used in the construction of the model. The research results show that the accuracy rate of defect detection is about 95%, and the recall rate is 94%. Compared with other detection modules, the execution speed is greatly improved. The detection time of each image is only 0.027 s, which fully meets the purpose of industrial practical application.

This research has succeeded in implementing a PLC-Based Temperature Control System for Transferring Image Patterns to Copper Boards in PCB (Printed Circuit Board) Manufacturing. This tool is made to simplify and speed up the process of transferring image patterns to copper boards in PCB manufacture. This Regulatory System consists of HMI, PLC, Thermocouple, Transmitter Thermocouple, Heater, as well as iron coating mechanics. HMI serves to display the settings received by the PLC as well as a second controller. While the PLC functions as a data processing center needed by the system and the main controller, the thermocouple functions to issue an output in the form of voltage. Heater as a heater and Mechanics of iron layer as pressure on the copper board. The results of the research on this system are image patterns that can be transferred to the copper board automatically with a measured temperature range of 400C - 1000C.

The research object in the work is the printed circuit boards (PCB) Production technological process using the additive technology of photopolymer 3D printing. The existing problem is that the manufacturing process of single-sided and double-sided PCBs, simple in technology, from the third to the fifth accuracy class, requires the use of a large amount of consumables and technological equipment. In turn, this affects the cost of the product. The research subject is models and methods for manufacturing PCB using photopolymer 3D printing. In order to reduce the cost of materials: film or aerosol photoresist, as well as reduce the number of technological operations, applying photoresist and for the manufacture of PCBs stencils, it is proposed to use photopolymer 3D printing technologies for the manufacture of PCBs. The paper analyzes the costs of Plexiwire Resin Basic Orange Transparen photopolymer resin for the manufacture of single-sided PCBs and calculates the cost of the consumable (resin) compared to the costs of dry film photoresist. 60 % cost of consumables (photopolymer resin) compared to dry film photoresist for making single-sided PCBs. The work is aimed at determining the dependence of the geometric dimensions of the PСВs topology and the consumption of photopolymer resin on the technological parameters of photopolymer exposure. A regression correlation model of the dependence of resin consumption on exposure parameters has been developed and correlation coefficients have been calculated. It has been established that with an increase in the exposure time of the photopolymer resin, the consumption of the photopolymer resin increases and the deviation of the geometric dimensions of the PCBs topology increases, which in turn negatively affects the quality of the product. Therefore, using the obtained regression model, it is possible to calculate the influence of parameters on the PCB topology and reduce the deviation of conductor sizes and resin consumption.

PurposeTo present an update and the latest results from work on a project aimed at enabling printed circuit board (PCB) manufacturing to become more sustainable.Design/methodology/approachVarious individual treatment technologies were studied individually under laboratory conditions and then combined into a pilot‐scale demonstrator line that was used to process effluent from a nickel‐gold plating line in a PCB production environment.FindingsThe use of these novel processes, including special electroplating techniques, advanced oxidation methods and a new ion exchange system can be combined to give a more sustainable treatment process for effluent emanating from PCB manufacturing. The approach also generates high quality pure water that can be recycled and reused in the manufacturing process.Research limitations/implicationsThe combined technology has been demonstrated with a nickel‐gold plating line. Further development work should be undertaken to tailor the technology for other parts of the PCB manufacturing process.Originality/valueThe paper details how individual treatment technologies can be combined to enable a much more sustainable approach to PCB manufacturing which offers the benefits of reduced effluent levels and a source of high purity recycled water.

The need for the printed circuit board (PCB) industry to minimise its environmental impact is increasingly important, not only because of public lobbying but also because of the potential negative financial implications. For the industry to be competitive and to reduce its costs, it must therefore maximise the benefits of available environmental best practices. Since PCB manufacturing uses many processes that are potentially harmful to the environment, their negative impact can be significant. This also means, however, that there are major opportunities available through the adoption of waste minimisation and environmental best practices. This article outlines the advantages of adopting such practices within PCB manufacturing and details specific examples of where real improvements and savings can be made. Sources of further information are given and specific reference is made to the PCIF’s new PCB Industry Environmental Best Practice Guide.

Purpose– The purpose of this paper is to optimize experimental parameters and gain further insights into the plating process in the fabrication of high-density interconnections of printed circuit boards (PCBs) by the rotating disc electrode (RDE) model. Via metallization by copper electrodeposition for interconnection of PCBs has become increasingly important. In this metallization technique, copper is directly filled into the vias using special additives. To investigate electrochemical reaction mechanisms of electrodeposition in aqueous solutions, using experiments on an RDE is common practice.Design/methodology/approach– An electrochemical model is presented to describe the kinetics of copper electrodeposition on an RDE, which builds a bridge between the theoretical and experimental study for non-uniform copper electrodeposition in PCB manufacturing. Comsol Multiphysics, a multiphysics simulation platform, is invited to modeling flow field and potential distribution based on a two-dimensional (2D) axisymmetric physical modeling. The flow pattern in the electrolyte is determined by the 2D Navier–Stokes equations. Primary, secondary and tertiary current distributions are performed by the finite element method of multiphysics coupling.Findings– The ion concentration gradient near the cathode and the thickness of the diffusion layer under different rotating velocities are achieved by the finite element method of multiphysics coupling. The calculated concentration and boundary layer thicknesses agree well with those from the theoretical Levich equation. The effect of fluid flow on the current distribution over the electrode surface is also investigated in this model. The results reveal the impact of flow parameters on the current density distribution and thickness of plating layer, which are most concerned in the production of PCBs.Originality/value– By RDE electrochemical model, we build a bridge between the theoretical and experimental study for control of uniformity of plating layer by concentration boundary layer in PCB manufacturing. By means of a multiphysics coupling platform, we can accurately analyze and forecast the characteristic of the entire electrochemical system. These results reveal theoretical connections of current density distribution and plating thickness, with controlled parameters in the plating process to further help us comprehensively understand the mechanism of copper electrodeposition.

Embedding polymer optical waveguides (WGs) into printed circuit boards (PCBs) for intra-board or board-to-board high speed data communications requires polymer materials that are compatible and inert when exposed to common PCB manufacturing processes. Ensuring both WG functionality after chemical exposure and maintaining PCB manufacturing integrities within the production process is crucial for successful implementation. The PCB manufacturing flow is analyzed to expose major requirements that would be required for the successful implementation of polymer materials for embedded WG development. Chemical testing and analysis were performed on Dow Corning ® OE-4140 UV-Cured Optical Elastomer Core and Dow Corning® OE-4141 UV-Cured Optical Elastomer Cladding which are designed for low loss embedded optical WGs. Contamination testing was conducted to demonstrate polymer compatibility in both cured and uncured form. Various PCB chemicals were treated with uncured polymer material and tested for effective contamination. Fully polymerized multimode WGs were fabricated and exposed to PCB chemicals at temperatures and durations comparable to PCB manufacturing conditions. Chemical analysis shows that the chosen polymer is compatible and inert with most common PCB manufacturing processes.

Printed circuit boards, which are embedded in mobile phones, are complex composite materials containing valuable components of strategic and critical importance. With the number of mobile phone devices operating worldwide expected to reach 18bn by 2025, their low recycling rate leads to high tonnages of waste printed circuit boards (WPCBs) at their end of life. Copper, representing 58% of the total metal content in an end-of-life mobile phone (EoL-MP) and the main metal present in the printed circuit board, with an average of 27.8 wt %, offers a resource-rich source of this strategic metal for recovery. To overcome the limitations associated with conventional technologies for recycling WPCBs, use of greener technologies (ionic liquids (ILs) as leaching agents), offers greater potential for the recovery of copper from this waste stream. Presented here for the first time is an optimised hydrometallurgical process for recovery of copper involving pre-treatment, leaching, and electrowinning and the use of two task-specific ionic liquids. The pre-treatment step, using the IL [Bmim]BF4 proved to be a clean, efficient, and non-polluting system for the separation of solder and electronic components (ECs) from WPCBs, at 210 °C, 150 rpm for 15 min, favouring the enrichment of copper for a subsequent recovery process. The IL, [Bmim]HSO4, successfully leaches >99% of copper from pretreated WPCBs under the optimal conditions of 30 %v/v [Bmim]HSO4, 10 %v/v H2O2, and 60 %v/v H2O at 60 °C, 1:15 solid to liquid ratio for 2 h. Recovery of copper is achieved through direct electrowinning from the [Bmim]HSO4-leach solution, as electrolyte. Under controlled deposition conditions of 100 mA (4.2 V) during 2 h, 100% of copper (>99% purity) is recovered with an average current efficiency of 78% and an energy consumption of 4.5 kWh/kg Cu. This work combines a dual leaching and electrowinning system that is clean, environmentally friendly, minimises reagent use and spent wastes, permits multiple reuses of both the ILs, and maximises resource conservation through recovery of copper metal and return of secondary streams (electronic components and solder) for reuse in new or refurbished components or products.

Purpose – This paper presents a novel printed circuit board (PCB) film image alignment method based on distance context of image components, which can be directly used for PCB film inspection. PCB film inspection plays a very important role in PCB production. Design/methodology/approach – First, image components of reference film image and inspected film image are extracted. Then, local distance context (LDC) and global distance context (GDC) are computed for each image component. Using LDC and GDC, the similarity of each pair of components between the reference film image and the inspected film image are computed, the component correspondences can be established accordingly and the parameters for aligning these two images can be eventually estimated. Findings – LDC and GDC act as the local spatial distribution descriptor and the global relative position descriptor of the current component, and they are invariant to translation, rotating and scale. Experimental results on aligning real PCB film images against various rotations and scaling transformation show that the proposed algorithm is fast and accurate and is very suitable for PCB film inspection. Research limitations/implications – The proposed algorithm is suitable for aligning those images that have some isolated connected components, such as the PCB film images. It is not suitable for general image alignment. Originality/value – We put forward to use LDC and GDC as the local descriptor and global descriptor of an image component, and designed a PCB film image alignment algorithm that can overcome the shortcomings of that image alignment algorithm that was based on local feature descriptors such as Fourier descriptor.