A Study On The Electrochemical Regeneration Of Acidic Cupric Chloride Etchant And Modification Of The Graphic Felt Anode

Acidic cupric chloride etchant is a kind of etchant widely used in Printed circuitboard industry, the constitute of the etchant is CuCl2and HCl. Along with the reactionof etching, the increasing in concentration of Cu(I) lead to fresh etching change tospent etching solution. According to statistics,6000tons or more spent etchant aregenerated every day in China’s PCB factories, contain about600tons metallic copper.If they can be recycled properly, not only it will gain a huge benefit in economic, butalso meaningful to protect the environment and cyclicutilization of resource. However,electrolytic etchant regeneration has not been widely adopted so far for technologicaland/or economic reasons.Using graphite felt as anode for electrochemical regeneration of acidic cupricchloride etchant, and investigating the result of regeneration. Results show that afterelectrochemical regeneration the etchant reach the level of fresh etchant, no dangergas generating, voltage of electrolytic cell is1.8V, lower than predecessor’s work. Byelectrochemistry test, we find that graphite felt have larger real surface area andhigher chlorine evolution potential compared with Pt. Therefore，graphite felt canrestrain the generation of chlorine。Taking advantage of Nafion’s characteristic in transmit cation but prevent anion,We modify the graphite electrode with Nafion membrane. By electrochemistry test,we find that graphite felt modified by Nafion has a higher chlorine evolution potentialin highly current density. Therefore，modify the graphite electrode with Nafionmembrane can restrain the generation of chlorine。In order to improve the electrochemical activity of anode in the electrochemicalregeneration of acidic cupric chloride etchant, the graphic felt anode is doped withnitrogen using urea. X-ray photoelectron spectroscopy (XPS) and fouriertransformation infrared spectroscopy (FT-IR) are carried to characterize the elementsand functional groups on the graphic felts. The results show that the nitrogencontentof graphic felt increases by2.68%. Cyclic voltammetry (CV) and linear sweepvoltammetry (LSV）are adopted to investigate the electrochemical properties of the graphic felt. The graphic felt treated in700℃for12h exhibits the bestelectrochemical activity toward Cu(I) oxidation.