Effect of CeO2 particles on the high phosphorus electroless Ni layer

Electroless Ni (EN) technology is widely used in electronic package field and the high phosphorus composite EN technology was studied. In this paper, we discussed the influence of nano-CeO2 and micro-CeO2 particles with different amounts when they were added in high phosphorus content Ni-P composite coating. The microstructure and crystal structure of the coating were observed by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD) respectively. The results showed that whether nano-CeO2 or micro-CeO2, both refined the grain, increased the specific surface area, however the micro-CeO2 particles made more obvious effect. As the XRD result showed, the peak gradually become gentle, the coating turned into amorphous which may cause by the CeO2 particles absorbed in the grain boundary and crystal defects. The results indicated the CeO2 deposited with the coating very well. Finally, the corrosion resistance of the coating was tested with the method of electrochemical impedance (EIS) and linear polarization. The results were unified. When the dosage is 5g/L, the corrosion resistance was the best. However, lower corrosion resistance was got when excessive CeO2 particles were added which may affect by the catalytic property.