Selective Desoldering Separation of Tin–Lead Alloy for Dismantling of Electronic Components from Printed Circuit Boards

Abstract

Desoldering separation of solder from waste printed circuit boards (PCBs) is a key step to recycle or dispose the electronic waste effectively. In the present work, a novel way for selective desoldering separation was achieved by dissolving lead−tin solder in fluoroboric acid containing H 2 O 2 . This leachant was observed possible to take the solder into solution with negligible dissolution of copper or other metals within 35 min. After leaching, the electronic components (ECs) could be easily removed from the boards under good experiment conditions. The effects of oxidants, dosage of H 2 O 2 , and acid concentration were explored to obtain the suitable experimental conditions. The results showed that 2.5 mol/L fluoroboric acid containing 0.4 mol/L added oxidant H 2 O 2 within the reaction of 35 min could be regarded as the optimum conditions for the selective desoldering separation from the waste PCBs. Both theoretical analysis using HSC Chemistry software and actual waste PCBs examination verified that the solder could be dissolved selectively by this novel process via excess solder added to inhibit the effect of copper dissolution if exists. This safe, fast, economic, and environmentally friendly dismantling PCBs process would be of great importance in recycling waste electrical and electronic equipment (EEE) effectively.

Measuring the recyclability of e-waste: an innovative method and its implications

“…The entropy H and grade D tend to be within the ranges of 1.5e3.0 bit and 2.4e6.5, respectively. The maximum (6.4) is from printed circuit boards (PCBs) and the minimum (2.5) is from printed wiring boards (PWBs) dismantled from PCBs, because more than sixty elements were found in PCBs (Adie et al, 2014;Johnson et al, 2007), and the dismantling of PCBs is usually required for the comprehensive recycling process (Hadi et al, 2015;Zhang et al, 2015).…”

Efficient In Situ Utilization of Caustic for Sequential Recovery and Separation of Sn, Fe, and Cu in Microbial Fuel Cells

“…Sn and Fe can be produced from crystallization of inorganics in stripping solutions from PrCB manufacturing ,,. Crystal precipitation occurs when concentrations of Sn(IV), Fe(III) or Cu(II) and caustic exceed the solubility limit for Sn(OH) 4 (1.0×10 −56 ), Fe(OH) 3 (2.8×10 −39 ) or Cu(OH) 2 (2.2×10 −20 ) (Eqs.…”

“…Solvent extraction, chemical precipitation and flocculation, and electrochemical deposition have been typically employed to recover Sn, Cu and Fe from stripping solutions generated from PrCB manufacturing ,,. However, the entire treatment process required pH adjustments by the addition of caustic (0.1–1.0 M), and the operational costs associated with continuous chemical addition or electricity consumption were high.…”

Dismantling of Electric and Electronic Components from Waste Printed Circuit Boards by Hydrochloric Acid Leaching with Stannic Ions

“…21) have shown PCB dismantling with automatic mechanical dismantling apparatus by employing diamond grinders. Because these thermal and mechanical separation processes have disadvantages such as consumption of high energy and loss of solder components, respectively, chemical dissolution processes have been investigated as an alternative method using a water-soluble ionic liquid 22) , methanesulfonic acid with hydrogen peroxide 23) , and uorob- oric acid with hydrogen peroxide 24) . However, the high cost of ionic liquid and the instability of hydrogen peroxide are signi cant drawbacks that hinder their use in commercial plants 25,26) .…”