An Environmentally Benign Process Model Development for Printed Circuit Board Recycling

Delaminating and separation of obsolete printed circuit board (PCB) is essential for its recycling. This paper presents an alternative environmentally benign process method for PCB recycling. Applying the solvent system, e.g. carbon dioxide and water under certain pressure and temperature, the PCB scraps could be delaminated easily. The separation of PCB into copper foil, glass fiber and polymer will be beneficial for further PCB recycling. The fundamental experiment mechanism is based on the polymer physics and polymerization. When the process temperature is raised above the polymer glass transition temperature Tg, polymer would be decomposed, which caused the main bonding force among PCB layers greatly reduced. Base on this principle several different processing circumstances were explored, including supercritical carbon dioxide; binary solvent system of CO₂ and H₂O; trinary solvent system of CO₂, H₂O and CH₃CH ₂OH. The experiment facilities were set up and the input & output parameters were defined to evaluate the PCB delaminating result. Utility functions were developed to optimize the process conditions. The recommendations for future study are illustrated at the end of this paper