Influence of intercolony boundary on corrosion behavior of electrodeposited Ni-W alloy for electronic connector applications

Electrodeposited Ni-W alloy has exhibited great potentials for electronic connector applications due to its superior corrosion resistance. However, deeper understanding of the influence the microstructure of electrodeposited Ni-W alloy thin film has on its anti-corrosive property is still required. A series of Ni-W coatings have been deposited by adjusting the thickness and W content in the coating. It was demonstrated that the corrosion behavior of Ni-W deposits was significantly affected by the boundary of a mesoscale structure called colony. As the density of intercolony boundary (DIB) increased from 6% to 28%, with W content and grain size fixed at 9.5 at.% and 13 nm respectively, the corrosion current density (I-corr)increased from 27.0 to 417.8 mu A/cm(2), suggesting a large decrease in corrosion resistance. When W content, grain size, and DIB changed simultaneously, their influence on the corrosion resistance became compositive.