Study on extending the life of electroless nickel plating solution

Sodium sulfate and sodium phosphite are tending to be accumulated gradually in the solution during electroless nickel plating,which affect the life of the plating solution.Method used to remove sodium sulfate and sodium phosphite in the plating solution was given.For nickel sulfate system,initially crystal sodium sulfate was removed by cooling the solution down to room temperature,and subsequently HPO~(2-)_3 was precipitated and removed by addition of Ca(OH)_2 at room temperature.For nickel hypophosphite system,HPO~(2-)_3 was precipitated and eliminated directly by adding Ca(OH)_2 at room temperature.The performances of plating solution and the properties of the deposit for the above two systems before and after treatment were respectively determined and compared,such as concentration of each component,solution density,plating speed and deposit stress,etc..The chemical precipitation method is feasible for extending the life of electroless nickel plating solution.