| In the view of the current PCB industry, that is, acid etching fluid system which has the disadvantage of "one-time use", the purpose of this study contains the flowing aspects of technology, economy and environment to select a most valuable type of acid etchant. The study includes the feasibility of recycling, and recycling use in various sectors of the best technical parameters. The research will provide helpful data for the PCB industry to promote cleaner production.The main contents of the study include:(1) make acid etchant of copper chloride, study the best parameters of the various components that impact etching rate (2) study the recovery process control from the impact of the two determining factors of etching rate decline of its renewable process control, including the theoretical calculations and process control; (3) recycle copper from the waste liquid, including the definition of recovery process and installation, the definition of parameters of different factors that impact recovery electric current and the morphology of the copper. (4) adjust the treatment component from copper and test the performance after recycle use.(5) give an evaluation to the recycle process, from the technical, economic and environmental aspects of the copper etching acid chloride.The results showed that acid etchant is technically feasible from the recycling process, it has technological, economic and environmental advantages over the traditional "one-time use" technology. (1) to measure the best operating conditions from hydrochloric acid and copper chloride acid chloride of the copper etching: temperature 50～55℃; Cu2+ concentration 120～150g/L, Cl- concentration not low than 200g/L, acid equivalent 2～3 N. Adding NH4Cl to the etched liquid, the etching rate increased slightly, but a large quantity crystalline precipitation in the solution will be generated at the lower temperature. (2) Process control of etching regeneration: H2O2 and HCl are mixed into oxygen solution of etching Cu+ on the ratio of about 1:2. To control the content of Cu+ in the etching fluid indirectly trough the redox potential calculator, oxidation-reduction potential range is 520～550mv; to detect indirectly the proportion of copper in the etching dissolution, the proportion range is 1.273 to 1.292;to add hydrogen peroxide into the etching fluid to reduce the decomposition stability and reduce the hydrogen peroxide consumption. (3) the installation of ion-exchange membrane-electrodeposited copper and the best technical parameters: the etching of the device can be placed in the cathode to avoid the emergence of Cl2 with a great amount, when cell voltage reachs 2.5v, cathode copper concentration is 52.7g/L, and temperature gets 30℃, the current efficiency gets the highest value 88.9%, and the shape of copper is plate. To electrolyze for 4 hours, the copper recovery may reach 82.5% and the etching rate can be 84.2%;(4) Analysis of copper recovery of post-processing component:content of Cl- is 136g/L, Cu2+ 6.8g/L, acid equivalent 2.3N. under the condition of best operating to indicate from the self-made acid etching, we adjust the content of Cl- and acid equivalent. Etching rate will not decrease significantly measuring in the laboratory conditions for five times. To compare samples we can find that etched production rate should be in line with demand. |
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