施镀时间对化学镀镍液阻抗谱及镀层表面形貌的影响

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

为了寻找一种可以简单方便测定化学镀液寿命的检测方法,考察了经不同施镀时间后的镀液的电化学阻抗谱(EIS)行为。结果发现,化学镀液的EIS都表现出具有2个时间常数的特征,在中频区,界面电荷传递电阻(Rd值)随施镀时间延长而显著增大,表明镀层表面晶体生长速率变慢,沉积速度降低。新配制镀液的Rd值为177.4Ω·cm2,而施镀2h后镀液的Rd值增至798.5Ω·cm2。原子力显微镜(AFM)的观察结果表明,施镀时间越长,镀层表面越粗糙。施镀1h的镀层表面纵向高度差约为1.1μm,而施镀3h后镀层表面纵向高度差达到1.6μm。

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 Rd increased significantly with increasing plating time in the intermediate frequency, exhibiting a decrease in deposition rate. The Rd value of the freshly prepared plating bath was 177.4Ω·cm2, and Rd value 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 1 h was about 1.1μm, whereas the vertical height difference of the coating deposited with 3 h increased to 1.6μm.