Atmospheric corrosion resistance of electroplated Ni/Ni–P/Au electronic contacts

• Ni/Ni–P stacks are studied for corrosion resistance in mixed flow gas and salt spray.
• Thicker Ni-P improves corrosion resistance in the mixed flow gas test.
• However, a thicker Ni–P layer performs the worst in the salt spray test.
• Corrosion mechanism is understood through analysis of corrosion pits and residues.

Atmospheric corrosion has vast consequences on the reliability of electronic connectors. This study determined the corrosion resistance of Ni/Ni–P plating metallurgy as a function of plating current density and plating thickness. Discrepancy was observed in the neutral salt spray (NSS) and mixed flowing gas (MFG) tests. Thicker Ni–P deposits displayed superior corrosion resistance in MFG tests while thinner Ni–P deposits performed better in NSS tests. This disparity was attributed to the intrinsic corrosion susceptibility of Ni–P against chlorine or sulfur assisted corrosion. Corrosion products were analysed for better understanding of the corrosion mechanism. NSS test produced green corrosion residues consisting of CuCl (nantokite) and CuCl2(OH)3 (clinoatacamite) and brown residues consisting of Cu2O (cuprite). MFG test produced sulfides of copper (major) and nickel (minor).

Figure optionsDownload as PowerPoint slide