A study on the utilization of scrap PC board

• Main Authors: R.S.shie, 謝仁紹
• Other Authors: Y.L.Yeh
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/87544007697481847301

碩士 === 明新科技大學 === 化學工程研究所 === 95 === PC board is made from fiber glass reinforced epoxy resin on which there is copper circuited with gold or tin. Only gold is recovered from the PC board traditionally by burning/aqua water dissolving method. This method not only contaminates the air by dioxin but also pollutes the underground water and rivers by heavy metals. This study developed a new process which causes no pollution problem and also fully utilized all materials of the PC board. First placed the PC board powder obtained into NH3/NH5CO3 solution to dissolve copper. The soluble copper ammonium complex ion is then heated to remove ammonia and copper carbonate is precipitated out from the solution. Ammonia can be recycled and reused. Next copper carbonate is heated at higher temperature to produce product of copper oxide. The optimum condition of this leaching process was as follows: 100g of PC powder、188.60mL of ammonia、74.60g of NH5CO3 and 2 days of leaching time at ambient temperature. The copper can be 100％ leached into the leaching solution. After the PC board powder was leached，hydrochloric acid、sodium hydroxide or fluosilicic acid were then added into the remaining power to dissolve tin and lead. The optimum condition of leaching was as follows: 50g of copper leached PC powder，6N hydrochloric acid and 1day of leaching time at ambient temperature. The dissolved efficiency was quite high for the tin and lead metals. The gold remained in the PC board was dissolved by immersing the powder into the thiourea solution. The optimum condition of leaching was as follows: 10g of PC powder、10g of thiourea、10 mL/L concentration of sulfuric acid and O2 as an oxidant and 7 days of leaching time at room temperature. The result of gold-leaching was poor. The PVC plastic with 9% PC board powder as filler was found to have the similar tensile strength as original plastics, and also had higher elastic modulus as well as higher scratch resistance. Above all it was cheaper. Accordingly the applications wasted of PC board not only transformed the plastic products with high supplementary value but also offered the significant contribution to environmental protection.