An environmentally benign supercritical fluid process for printed wiring board recycling

dc.creatorYuan, Yingchun Engineeringen_US
dc.description.abstractThis research is focused on development of an alternative recycling process for printed wiring boards (PWBs). With huge amounts of electronic products becoming obsolete each year, the numerous kinds of PWBs from these obsolete electronics cause grave environmental concerns in both society and governmental agencies due to their toxic material composition and complicated physical structures. Although some techniques such as incinerations and shredding are currently employed for recycling PWB scraps by hundreds of electronic recyclers, these techniques are not efficient from environmental and economic views. This project is proposed to address both the environmental and economic demands for PWB recycling processes. In the research, supercritical fluid CO2 is employed to treat the PWB scraps which will cause decomposition of various resins in PWB substrates. Since resins are the bond materials between PWB layers, the complete decomposition of all resins would automatically cause the delaminating of PWB boards when the process is subject to rapid depressurizations to induce sufficient forming effect. To study the supercritical fluid treatment effect, weight reduction percent of PWBs is used as index for measuring resin decomposition effect. Five kinds of bare PWBs from Canada and USA companies are used as specimen in the experiment which is studied based on the factorial experiment design method. In addition, water is added as an environmental benign co-solvent to supercritical fluid CO2 and its effect in enhancing the interactions is investigated. From the systematic study, it is found that temperature is the most influential factor on the PWB decomposition effect. Pressure plays an importance role but not critical when it is in effective regions. Three hours is good enough for a complete interaction between PWBs and SCF CO2. Addition of 7 mole % of water can greatly enhance the delaminating effect and surface cracking during the reaction process, which is significant for real application of the process in future.
dc.publisherTexas Tech Universityen_US
dc.subjectPrinted circuits -- Waste disposalen_US
dc.subjectPrinted circuits -- Environmental aspectsen_US
dc.subjectSupercritical fluidsen_US
dc.subjectPrinted circuits -- Scrappingen_US
dc.subjectHazardous wastesen_US
dc.titleAn environmentally benign supercritical fluid process for printed wiring board recycling