A physical process for recycling and reusing waste printed circuit boards

This paper presents a practical physical process for recycling waste printed circuit boards (PCBs) as well as the reusing process for epoxy resin recovered from PCBs. A special crusher with extra extruding, impacting and shearing forces was developed. With this crusher, the glass-reinforced PCBs could be readily crushed to proper granularity. In order to reduce the toxic gases and dusts released from the crushing process, a cooling-spray technology was developed, which reduced toxic gases and dusts significantly. After the latter powder-making and separation process, the liberation degree of metals from nonmetals exceeded 95%, and the toxic heavy metal content, such as Cd and Cr, found in the non-metals powder was far below the allowable limit according to the national criteria. In addition, the entire recycling process was built as a closed loop system and the recycling process was environmentally sound. With the use of special designed multilevel leaching device and labyrinth-type backwater trough, water circulates round the whole process and almost no waste water was let out. At present, the research on reusing recovered resin powder focuses mainly on using resin as fillers for paint, construction materials, etc, A series of reuse experiments which have been carried out are also discussed in this paper.

I. Introduction

Printed circuit board (PCB) is the typical and fundamental component for almost all electronic products. With the development of electronic products, the amount of waste PCBs is increasing sharply and has caused severe environmental problems. Recycling and reusing waste PCBs have become a common matter in many countries.