A Study On The Electrochemical Regeneration Of Printed Circuit Board Etchant And Modification Of The Graphite Felt Anode

Acidic cupric chloride etchant is s kind of etchant widely used in printed circuit board industry,the main content of the etchant is CuCl2 and HCl.Along with the reaction of etching solution.The increasing in concentration of Cu(I)lead to fresh etching change to spent etching solution.According to statistics,8000 tons or more spent etchant are generated every day in China's PCB factories,contain about 900 tons metallic copper.They should be recycled properly.However,electrolytic etchant regeneration has not been widely adopted so for technological and /or economic reasons.Using graphite felt as anode for electrochemical regeneration of acidic cupric chloride etchant,and investigation the result of regeneration.Result show that after electrochemical regeneration the etchant reach the level of fresh etchant,no Cl2 generating.Voltage of electrolytic cell is 1.25 V at the current density of 30mA·cm-2,lower than predecessor's work.By using the electrochemical regeneration cell at the current density of 40 mA·cm-2,we can get the copper electro-deposition with a smooth surface on the copper cathode without any particle copper.In order to improve the electrochemical activity of anode in the electrochemical regeneration of acidic cupric chloride etchant,the graphite felt anode is activated with KOH and modified with CNT by CVD method,respectively.The graphite felt activation with KOH is also adopted as the anode in the electrochemical regeneration of acidic cupric chloride etchant.X-ray photoelectron spectroscopy(XPS)is carried to characterize the elements and functional groups on the graphite felts.The results show that the oxygen content of graphite increases to 6.27 %.CV and EIS are adopted to investigate the electrochemical properties of the graphite felt.The graphite felt activated with KOH in 900 °C exhibits the best electrochemical activity towards Cu(I)electrochemical oxidation.Compared with the untreated graphite felt,the voltage and the anode potential is smaller for the electrochemical regeneration of PCB etchant.The graphite felt is also used to grow CNT on the surface of carbon fiber by using CVD method,and the graphite felt modified with CNT is adopted as the anode of electrochemical regeneration of acidic cupric chloride.SEM and TEM are carried to characterize the morphology and microstructure of the graphite modification with CNT.The results of XPS show that there are more defective sites on the surface of the graphite felt treated with CVD method in 1100 °C.CV is adopted to investigate the electrochemical properties of the graphite felt.The graphite felt treated with CVD method in 1100 °C exhibits the best electrochemical activity towards Cu(I)electrochemical oxidation.Compared with the AGF-900,the cell voltage and the anode potential of the graphite felt modified with CNT in 1100 °C is lower for the electrochemical regeneration of PCB etchant.