Disassembly is essential when components on retired PCBs are treated separately to increase the total income of reutilization. By comparing structural characteristics, value distribution and ...disassembling difficulty of various components, our research set two goals for PCB disassembly: one is to resume functional value of some SMT components with high density of function and the other is to retrieve material value of the rest components. Correspondingly, disassembling approaches can be classified into two categories: quality ensured disassembly for the first goal and destructive disassembly for the second goal. Simultaneous approaches are expected to cut down on cost and time consumption of quality ensured disassembly. However, simultaneous disassembly tends to cause more failures on components than stepwise disassembly. To provide reference for adapting approaches and equipments to simultaneous disassembly, several modes of mechanical failure of disassembled components and their causes are presented based on testing and analysis. We also present a design on adapting the air heating approach to simultaneous disassembly and discuss benefits of applying disassembly in material retrieval of PCBs.
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.
In waste printed circuit boards (PCBs) recycling fields, how to recycle and reuse nonmetals is a challenging problem, and there is no preferable solutions up to now. This paper presents new methods ...for reusing nonmetals reclaimed from waste PCBs. Nonmetals are used to make formative models, compound boards or related products. When compared with traditional materials, such as talc and silica powder, PCB nonmetals improve the mechanical features of these products greatly with comparable tensile and shearing strength and 30 percent larger flexural strength, which indicates good application prospect for its undoubted potential.
