Regeneration of sulphuric acid, per:oxo:di:sulphate etching solns. contg. copper - by using a process requiring no interruptions for accumulated copper@ removal

摘要

The method for regeneration of sulphuric-acid, peroxodisulphate etching solutions containing copper consists of cathodic reduction and precipitation of the bulk of copper in a copper recovery cell, followed by copper precipitation and regeneration of the peroxodisulphate respectively in the cathode and anode spaces of a divided peroxodisulphate regeneration cell. The solution from the copper recovery cell has a residual copper content from 0.05 to 5 g/litre. With optimal adjustment of the regeneration cell, regeneration of the etching solution can be carried out with an energy consumption of 1/7 kWh per kg of sodium peroxodisulphate. The cell operates with bubble-driven catholyte circulation and continuous removal of precipitated residual copper by means of integrated solid/liquid separation stages. USE/ADVANTAGE - The process can be used in manufacture of printed circuit boards. It is environment-friendly and does not have to be interrupted for removal of accumulated copper.