S.H. Hsieh

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.