Effective separation of waste printed circuit boards using microwave-assisted organic swelling.

Nowadays, our lifestyle demands more electronics products, and this rapid development generated an increase in the amount of electronic waste (e-waste). Waste printed circuit boards (WPCBs) are components in all electronic devices and responsible for a high percentage of the total weight of the generated e-waste worldwide. WPCBs are composed of fiberglass reinforced epoxy composites and additives. The critical step in recycling WPCBs is to separate the non-metallic and metallic components by removing the epoxy resins. In this work, a new method is proposed to separate the several layers of the WPCBs using organic solvents under microwave conditions. Firstly, various solvents capable of dissolving the brominated epoxy resin from WPCBs were selected based on the calculation of Hansen solubility parameters. All chosen solvents were tested by microwave and then compared with methods previously described (thermostatic and ultrasonic baths). Microwave showed to be the most efficient and rapid approach. The best conditions were WPCBs dimensions of 225 mm2 using N-methylpyrrolidone (S/L ratio of 300g/L) at 200 ºC with 2 cycles of 10 min. This method showed to be an efficient, fast and eco-friendly choice over the technologies available for delaminating totally WPCBs into metallic and non-metallic components.