RESEARCH OF ROUGHNESS OF COPPER SURFACE OF PRINTED CIRCUIT BOARDS AFTER CHEMICAL PROCESSING

2020 ◽  
Author(s):  
Ольга Валерьевна Кирсанова
Keyword(s):  
Nitric Acid ◽  
Printed Circuit Boards ◽  
Copper Surface ◽  
Ferric Nitrate ◽  
Chemical Processing ◽  
Circuit Boards ◽  
Printed Circuit

Экспериментально исследован травитель на основе азотной кислоты и железа азотнокислого со специальными добавками для удаления гальванического олова-свинца с поверхности печатных плат, создающий достаточную шероховатость поверхности меди. An etchant based on nitric acid and ferric nitrate with special additives to remove galvanic tin-lead from the surface of printed circuit boards was experimentally studied, which creates a sufficient roughness of the surface of copper.

scholarly journals Usage of Sims and Auger Test Methods in the Production of Multilayer Printed Circuit Boards

1984 ◽  
Vol 11 (3) ◽  
pp. 225-229
Author(s):  
E. Toth ◽  
P. Banlaki ◽  
I. Hajdu ◽  
J. Pinkola
Keyword(s):  
Copper Foil ◽  
Printed Circuit Boards ◽  
Copper Surface ◽  
Test Methods ◽  
Main Constituent ◽  
Circuit Boards ◽  
Adhesion Properties ◽  
Printed Circuit ◽  
Quality And Reliability ◽  
Type Electrolyte

The quality and reliability of multilayer boards are determined by the adhesion strength between the copper sheets and the epoxy-glass laminates. The adhesion properties of copper foil may be improved by mechanical or chemical roughening. The most efficient method is, however, to oxidize the copper surface.Oxidized copper layers have been tested by thermogravimetry. Subsequently the oxide layers have been tested by Auger and SIMS techniques. The results showed that the main constituent of the oxide layer produced in a sodium hypochlorite type electrolyte is Cu20.

Metal Leaching Efficiency from Waste Printed Circuit Boards by Inorganic Acid

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.

scholarly journals Resources Recovery from Electronic Waste

2020 ◽  
Author(s):  
Mohit Arora
Keyword(s):  
Nitric Acid ◽  
Printed Circuit Boards ◽  
Extraction Efficiency ◽  
Electronic Waste ◽  
Mineral Processing ◽  
Metal Recovery ◽  
Circuit Boards ◽  
Gold Extraction ◽  
Printed Circuit ◽  
Thiosulfate Leaching

Printed Circuit Boards in electronic scrap are richest source of base and precious metals, promoting economic drive for metal recovery. Recovery of these metals is a difficult exercise due to complex nature of electronic waste. India is one of the leading electronic waste processing hubs where more than 95% recyclers are unorganised/non-formal, lacking such a recovery facility. An efficient metal recovery protocol with lesser environmental impact remains unavailable to unorganised recyclers. In current study, an attempt has been made to combine various hydrometallurgical methods to achieve efficient metal recovery from Printed Circuit Boards. Mimicking mineral processing protocols for metal recovery from electronic waste has been a key feature of presented research. Printed Circuit Boards of personal computers were reduced to a size ≤ 2.5 mm and were used as sample for metal recovery. Copper and silver were extracted by selective leaching using Nitric Acid. Maximum extraction efficiency of 96.8% and 99.9% were achieved for copper and silver respectively. Nitric Acid was extracted using solvent extraction method to minimize the environmental damage of remaining waste as well as for reuse in next leaching cycle. Electrodeposition of copper was done on copper cathode with stainless steel and lead anodes with a maximum recovery efficiency of 89.6%. For extraction and recovery of gold and silver, various techniques used in mineral processing were applied in this research. Thiosulfate leaching was chosen for gold extraction due to its proven environment friendly properties. Maximum gold extraction efficiency of 74.3% has been achieved in this work. To recover gold from pregnant solution, zinc cementation approach was used. Up to 85.9% gold was recovered with zinc cementation. Success of thiosulfate leaching and cementation confirms the validity of mineralprocessing techniques in metal recovery from electronic waste. Research in this study can serve as a backbone for potential environmentally sound technology towards efficient metal recovery from electronic waste for small and medium scale recyclers.

scholarly journals The Effect of Shredding and Particle Size in Physical and Chemical Processing of Printed Circuit Boards Waste

2012 ◽  
Vol 730-732 ◽  
pp. 653-658
Author(s):  
Paula C. Oliveira ◽  
Filipa Charters Taborda ◽  
Carlos A. Nogueira ◽  
Fernanda Margarido
Keyword(s):  
Particle Size ◽  
Printed Circuit Boards ◽  
Chemical Reactivity ◽  
Reaction Rates ◽  
Chemical Processing ◽  
Particle Sizes ◽  
Circuit Boards ◽  
Adequate Treatment ◽  
Printed Circuit ◽  
Physical And Chemical

Circuit boards present in most electric and electronic devices are very important components, which should be removed during sorting and dismantling operations in order to allow further adequate treatment for recovering valuable metals such as copper, nickel, zinc, lead, tin and rare elements. This recovery can be made by physical and chemical processes being size reduction by shredding the first step. In this paper, the effect of particle size in physical and chemical processing of printed circuit boards is presented and discussed. Shredding using cutting-based equipment allowed the comminution of boards and the liberation of particles composed by different materials (mainly metals and resin). Particle sizes less than 1 mm seems to be appropriate to attain high liberation of materials, which is crucial for the physical separation using gravity or electrostatic processes. Concerning chemical treatment, hydrometallurgical processing involves a leaching operation which can be also influenced by particle size of shredded boards. Samples with different granulometries were leached with 1 M HNO3 solutions, being leaching yields evaluated. It was concluded that particle size can be an important factor for the solubilization of some metals, but the effect is not similar for all elements. When average diameters change from 2.0 to 0.20 mm, nickel, aluminium and tin reactivity were not significantly affected, being this effect important for copper. Zinc behavior was very dependent from extreme particle sizes but was less affected in intermediate granulometries. Lead leaching showed also a peculiar behavior, exhibiting high and almost constant yields (80-90%) for particle size of solids up to 1.2 mm, and decreasing suddenly for higher granulometries. The effect of time on chemical reactivity for samples with different granulometries demonstrated that particle size affects reaction rates but eventually similar efficiencies can be obtained for long time periods. Therefore the relationship between results from shredding operation and chemical leaching step needs to be optimized, considering the balance between factors like consumption of energy during grinding operation and residence time in leaching.

Slit Effect of Common Ground Patterns in Affecting Cross-Talk Noise between Two Parallel Signal Traces on Printed Circuit Boards

2008 ◽  
Vol 128 (11) ◽  
pp. 657-662 ◽  
Author(s):  
Tsuyoshi Maeno ◽  
Yukihiko Sakurai ◽  
Takanori Unou ◽  
Kouji Ichikawa ◽  
Osamu Fujiwara
Keyword(s):  
Cross Talk ◽  
Printed Circuit Boards ◽  
Common Ground ◽  
Circuit Boards ◽  
Printed Circuit
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