The influence mechanism of flash Joule heating on the pore structure and the diffusion of Ag in printed circuit boards

MY Sun and DK Hong and T Xu and MF Zhang and Y Zhang and CB Wang, ENERGY, 326, 136250 (2025).

DOI: 10.1016/j.energy.2025.136250

The recovery of precious metals from e-waste is of great interest due to their high economic value and environmental benefits. Traditional recycling methods suffer from a number of problems, including cumbersome processing and negative environmental impacts. However, flash Joule heating (FJH), a solvent-free and sustainable process for recovering precious metals, is proposed to achieve high recovery rates while being environmentally friendly. In this paper, the recovery process of Ag in the printed circuit boards (PCBs) was simulated and the influence mechanism of FJH on PCB structure was explored via ReaxFF-MD. Mean square displacement (MSD) results showed that PCBs treated with FJH were more beneficial for Ag diffusion. Then, the internal structure of FJH- treated PCBs was analyzed. It is concluded that the free volume fraction and porosity of PCBs increased, and the pore size distribution was more favorable for the diffusion of Ag. Finally, the influence mechanism of porosity change in PCBs was explored. During the FJH process, the porosity first increased and then decreased. The moment of maximum porosity corresponded to the minimum point of helium density in PCBs, which was also the optimal time for recovery.

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