A new industrial technology for closing the loop of full-size waste motherboards using chemical-ultrasonic-mechanical treatment

Abstract

Development of a new sustainable pilot scale technology for recycling of Waste Printed Circuit Boards (WPCBs) is a challenging and time-consuming task, especially since the situation with electronic waste is worsening yearly in terms of environmental hazard and valuable material loss. Therefore, this research is oriented towards quickly approaching the industrial level and recycling a full-size waste motherboard (MB) using a combined technique presented by three treatment types: chemical, ultrasonic, and mechanical. Here, chemical is the main treatment type with an aim to liquefy Brominated Epoxy Resin (BER) using an organic solvent eventually separating all layers of MB, while mechanical and ultrasonic treatments are used to accelerate the BER dissolution process. The treatment was performed in a new reactor designed especially for that purpose. Spent solvent was regenerated several times during the treatment by a rotary evaporator to avoid solvent saturation as well as to extract the BER. Ultraviolet-Visible Spectroscopy, FTIR, NMR, metallographic microscope, SEM and EDX were the used to study the obtained BER, fiberglass, and metal. The results indicated that MB was composed of five fiberglass layers adhered by BER (67wt.%), two copper layers and tracks (19.4wt.%), through-hole pads (12wt.%). In addition, it was noted that through-hole pads contained Palladium coating. Finally, based on the economic evaluation of the new technology, a conclusion was drawn that the application of this technology on an industrial scale can provide an economic return up to ∼2,300$ per ton of WPCBs (without precious metals recovery). In addition, applying the developed approach on an industrial scale gives a possibility to decrease carbon footprint by −1868kg CO2-eq/t of WPCBs.