Effects of Plating Time on the Electrochemical Impedance Spectroscopy of Electroless Plating Bath and Roughness of Coatings

In order to develop a simple and convenient analytical method to measure the life of electroless nickel plating bath,the electrochemical impedance spectroscopy(EIS)behavior of electroless nickel plating bath with different plating time was studied.It was found that all the EIS of the plating bath exhibit two time constants,the values of Rdincreased significantly with increasing plating time in the intermediate frequency,exhibiting a decrease in deposition rate.The Rdvalue of the freshly prepared plating bath was 177.4Ω·cm2,and Rdvalue of the plating bath after plating two hours increased to 798.5Ω·cm2.Atomic force microscopy(AFM)observation showed that the surface roughness of the Ni-P alloy coatings increased with increasing plating time when the plating bath was not replenished or the plating parameters was not adjusted.The vertical height difference of the coating deposited with 1hwas about1.1μm,whereas the vertical height difference of the coating deposited with 3hincreased to 1.6μm.