Optimization of process parameters for the chemical leaching of base metals from telecom and desktop printed circuit boards

AbstractThis paper describes the application of laser micromachining to rapid prototyping of printed circuit boards (PCB) using nano-second lasers: the solid-state Nd:YAG (532/1064 nm) laser and the Yb:glass fiber laser (1060 nm). Our investigations included tests for various mask types (synthetic lacquer, light-sensitive emulsion and tin). The purpose of these tests was to determine some of the basic parameters such as the resolution of PCB prototyping, speed of processing and quality of PCB mapping with commonly available laser systems. Optimization of process parameters and the proposed conversion algorithm have allowed us to produce circuit boards with a resolution similar to that of the Laser Direct Imaging (LDI) technology.

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Recovery of copper and the deportment of other base metals from alkaline glycine leachates derived from waste printed circuit boards (WPCBs)

Hydrometallurgy ◽

10.1016/j.hydromet.2020.105540 ◽

2021 ◽

Vol 199 ◽

pp. 105540

Author(s):

Huan Li ◽

Elsayed Oraby ◽

Jacques Eksteen

Keyword(s):

Printed Circuit Boards ◽

Base Metals ◽

Circuit Boards ◽

Printed Circuit ◽

Waste Printed Circuit Boards

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Metal Leaching Efficiency from Waste Printed Circuit Boards by Inorganic Acid

The Journal of Solid Waste Technology and Management ◽

10.5276/jswtm/2019.355 ◽

2019 ◽

Vol 45 (3) ◽

pp. 355-362

Author(s):

Zhenfeng Xiong ◽

Ying Huang ◽

Kemei Zhou ◽

Dong Zhang ◽

Juan Bao ◽

...

Keyword(s):

Nitric Acid ◽

Printed Circuit Boards ◽

Base Metals ◽

Circuit Boards ◽

Aqua Regia ◽

Printed Circuit ◽

Waste Printed Circuit Boards ◽

Inorganic Acids ◽

Mass Fractions ◽

Leaching Efficiency

Waste printed circuit boards (WPCBs) from personal computers were ground and subjected to a two-step leaching process using two inorganic acids (nitric acid and aqua regia) to leach metals. Three kinds of samples were used: the whole WPCB, the golden finger part, and the WPCB excluding the golden finger. Leaching efficiencies of metals from these samples for different nitric acid concentrations (followed by aqua regia) were evaluated to identify the best concentration of nitric acid. The extracted Au concentration from the golden finger was 5.5 times of that from the whole WPCB board. Metals that compete with Au, such as Ni and Fe, have lower mass fractions in the whole WPCB board compared to those in the golden finger. However, Cu comprises a higher proportion in the golden finger. Au can be effectively separated from most other metals by initially leaching the ground WPCB with 5M nitric acid, followed by leaching with aqua regia. Considering the high leaching proportion of Au, it is advantageous to leach Au and base metals separately from the golden finger and from WPCB excluding the golden finger.

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Development of a Physical Separation Route for the Concentration of Base Metals from Old Wasted Printed Circuit Boards

Minerals ◽

10.3390/min11091014 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1014

Author(s):

Pedro Jorge Walburga Keglevich de Buzin ◽

Weslei Monteiro Ambrós ◽

Irineu Antônio Schadach de Brum ◽

Rejane Maria Candiota Tubino ◽

Carlos Hoffmann Sampaio ◽

...

Keyword(s):

Printed Circuit Boards ◽

Electronic Devices ◽

Preliminary Evidence ◽

Composition Analysis ◽

Base Metals ◽

Circuit Boards ◽

Physical Separation ◽

Printed Circuit ◽

Processing Circuit

Wastes from old electronic devices represent a significant part of the electronic scrap generated in developing countries, being commonly sold by collectors as low-value material to recycling hubs abroad. Upgrading the quality of this waste type could drive the revenue of recyclers, and thus, boost the recycling market. On this basis, this study investigated the possibility of concentrating metals from old wasted printed circuit boards through a physical separation-based route. Preparation of samples comprised fragmentation, size classification, density, and magnetic separation steps, followed by chemical and macro composition analysis. Cu, Al, Fe, and Sn constituted the major metals encountered in the scraps, including some peak concentrations of Zn, Sb, Pb, Ba, and Mn. Four distinct concentrate products could be obtained after suitable processing: (a) a light fraction composed of plastics and resins; (b) an aluminum concentrate; (c) a magnetic material concentrate, containing mainly iron; (d) a final concentrate containing more than 50% in mass of copper and enriched with nonferrous metals. Preliminary evidence showed that further processes, like the separation of copper wires through drumming, can potentially improve the effectiveness of the proposed processing circuit and should guide future works.

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Chemical and microbial leaching of base metals from obsolete cell-phone printed circuit boards

Sustainable Environment Research ◽

10.1016/j.serj.2018.10.002 ◽

2018 ◽

Vol 28 (6) ◽

pp. 333-339 ◽

Cited By ~ 6

Author(s):

Bhumika R. Khatri ◽

Asha B. Sodha ◽

Monal B. Shah ◽

Devayani R. Tipre ◽

Shailesh R. Dave

Keyword(s):

Cell Phone ◽

Printed Circuit Boards ◽

Base Metals ◽

Circuit Boards ◽

Printed Circuit ◽

Microbial Leaching

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Prediction Model for Cu Chemical Leaching from Printed Circuit Boards

Industrial & Engineering Chemistry Research ◽

10.1021/acs.iecr.9b04187 ◽

2019 ◽

Vol 58 (45) ◽

pp. 20585-20591 ◽

Cited By ~ 1

Author(s):

Alessandro Becci ◽

Alessia Amato ◽

José Miguel Rodríguez Maroto ◽

Francesca Beolchini

Keyword(s):

Prediction Model ◽

Printed Circuit Boards ◽

Circuit Boards ◽

Chemical Leaching ◽

Printed Circuit

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Development of the Digital Site for Chemical Processes in the Manufacturing of Printed Circuit Boards

Inventions ◽

10.3390/inventions6030048 ◽

2021 ◽

Vol 6 (3) ◽

pp. 48

Author(s):

Fedor V. Vasilyev ◽

Arkadiy M. Medvedev ◽

Fedor A. Barakovsky ◽

Maksim A. Korobkov

Keyword(s):

Process Parameters ◽

Printed Circuit Boards ◽

Chemical Processes ◽

Circuit Boards ◽

Printed Circuit ◽

Digital Production ◽

System Components ◽

Digital Methods ◽

Controllable Process

The article defines digital methods for controlling the quality of chemical processes. An architecture of a digital production line, which ensures the distribution of the computational load between the system components, is proposed. We considered the process of developing a prototype of a digital production site for servicing the etching operation during which controllable process parameters are determined; both hardware and software structures of the digital site are proposed. Studying the site operability, we determined the relationships between the process parameters, which made it possible to determine the boundaries of the designed system.

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