Growth Behavior of Ni–P Film on Fe/Si Substrate in an Acid Electroless Plating Bath

Ni–P film was electrolessly deposited on Fe/Si substrate in an acid plating bath containing nickel sulfate as the nickel source and sodium hypophosphite as a reducing agent. The Fe film in Fe/Si substrate was formed by electron-beam evaporation deposition. The Ni–P film was characterized by transmission electron microscopy. The results showed that the Ni–P film on Fe/Si substrate has a homogeneous and nanocrystalline structure in comparison with that on Si substrate, which has a columnar structure, and there are straight cracks in the Ni–P film when the pH value of the plating bath is relatively high due to the higher internal tensile stress. The plating rates of Ni–P film on Fe/Si substrate increase with increase in plating temperature and pH value, ranging from 0.22 to 5.27 nm/s for plating temperatures of 65 – 90 ° C and pH values of 4.2–5.0. The activation energies of Ni–P films on Fe/Si substrate were 99.58, 87.4, and 41.55 kJ/mol for pH values of 4.2, 4.6, and 5.0, respectively.