Study On Cyclic Regeneration Of Microetching Of Peroxide System

The microetching is the important pretreatment step in the producing process of PCB(Printed Circuit Board).Its main function is to obtain coarse structure on the copper surface. After microetched the binding force should be strengened between copper-covered board and the plating layer. The pollution index of waste microetching solution is high,so the copper ions in the microetched solution must be recovered.And then the waste solution should be regenerated to imple its self-cycle.The performance of microetching and process of cyclic regeneration were studied for two kinds typical peroxide system in this paper.The optimum technological conditions of the sodium persulfate/sulfuric acid system were studied by the static corrosion method in the period of microetching. The experimental results show that under optimum conditions of maintaining temperature at 26-32℃, copper concentration at 9-15g/L, sodium persulfate concentration 75-125 g/L and sulfuric acid volume fraction of 2-4%,the rate of micro-etching is 0.5μm/min and the process is stable and controllable.The result of SEM showed the coarseness was increased.The optimum technological conditions of the hydrogen peroxide/sulfuric acid system were studied by the same method. The results of experiment showed that the etching performance was excellent when maintained hydrogen peroxide 30-40 g/L, copper concentration about 25 g/L, sulfuric acid content 70-90 g/L and temperature at 30-35℃. The conclusion can be drawn that under these conditions the process of micro-etching is stable and controllable. The result of SEM showed the surface of microetching was smooth, the roughness was uniform.In the stage of cyclic regeneration of microetched solution, copper was selectively reclaimed from the microetched liquid,by the electrodeposition technics. The experimental results show that the the current efficiency of copper electrodeposition was 96% under optimum conditions of electrolysis time 2h,copper contents 18～26g/L in the cathode chamber, operating temperature at 30～40℃, current density 2.4～3.0A/dm2.Copper is separated as tabular from the cathode chamber under the above conditions.After recovered copper the regenerateed microetching of two kinds of system was as good as that of the fresh microetching, crystallizing separation of sodium sulfate should be done to the sodium persulfate system, which can meet the PCB requirements.And these turn into a cleaner production process by using regeneration and reuse the treating method for the microetching in its usage and disposal.