Analysis of the reason of excessive consumption of chloride ion in PCB copper plating

At present, with the development of printed circuit board to high density and high precision, more stringent requirements are put forward for sulfate copper plating process. In view of the phenomenon of excessive consumption of chloride ions in the copper plating process, the causes of excessive consumption of chloride ions are analyzed below.

 

Antecedents of excessive chlorine ion consumption:

 

When copper plating, the low current area of the circuit board surface appears "dull" phenomenon, and the concentration of chlorine is low. Generally by adding hydrochloric acid, plate surface low current density area coating "luster" phenomenon can disappear, the concentration of chloride ions in the plating solution to reach the normal range, plate surface coating bright. If a large amount of hydrochloric acid is added to solve the "dull" phenomenon of the coating in the low current density area, it is not necessarily caused by the low concentration of chloride ions, and the real reason should be analyzed. If a large amount of hydrochloric acid is added, other consequences may be produced, and the production cost will be increased, which is not conducive to enterprise competition.

Correctly analyze the cause of "dull coating in low current density area" :

 

By adding a large amount of hydrochloric acid to eliminate the "low current density area coating is not bright" phenomenon, that is, if the chloride ion is too little, it is necessary to add hydrochloric acid to increase the concentration of chloride ion to reach the normal range, so that the low current density area coating is bright. What if you had to add multiples of hydrochloric acid to get the chloride concentration to the normal range? What's consuming a lot of chlorine? Too high a concentration of chloride ions will cause the brightener to wear out quickly. It indicates that chlorine ions will react with brightener, and excessive chlorine ions will be consumed. In turn, excess brightener also consumes chloride ions. Because too few chloride ions and brightener overdose are the main cause of low current density area coating is not bright ", so it can be seen that "copper plating in the main cause of excessive consumption of chloride ions is the brightener concentration is too high.