EFFECTS OF pH ON Ni COATING ON POLY(ETHYLENE TEREPHTHALATE) SUBSTRATE BY PRINTING PRIME IN COMBINATION WITH PALLADIUM ACTIVATING

Abstract

In this work, the primer-printed and then self-assembled poly(ethylene terephthalate) (PET) sheets were plated when the bath pH increased from 7 to 11. The e®ects of bath pH on the structural and electrical properties of electroless nickel plating were investigated systematically using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results showed that the crystallographic structures of Ni-plated PET (NPP) sheets were face centered cubic, the preferential orientation of the coatings changes from (200) plane to (111) plane, the growth rate of plated nickel coating increased from 3.71 m/min to 8.13 m/min, the average Ni crystal size was increased from 0.23 m to 0.92 m, the average EMI-SE of NPP sheets was increased from 37.2 dB to 38.6 dB and the surface electrical resistivity of NPP sheets was decreased from 6235 ohm Á cm to 0.03 ohm Á cm with the increase of bath pH. The changes in structural and electrical properties were most possibly due to the fact that the thickness of coating increased.