Development of High Performance Magnetic Ni-Fe-W-S Thin Film for Micro Electro Mechanical System

Electro deposition of NiFeWS thin films was carried out from Tri Potassium citrate bath at a constant current density (1 A/dm) and controlled pH of 8 by varying bath temperature. Physical properties such as surface morphology, microstructure and magnetic properties such as coercivity, saturation magnetization, magnetic flux density were investigated for electrodeposited NiFeWS soft magnetic thin films. The characteristics of the NiFeWS thin films were enhanced when the temperature of the bath increased. The SEM micrographs of the electrodeposited films at 80 ̊C exhibited no micro cracks and more uniform. According to X-ray diffraction pattern, the FCC structure was the dominant microstructure of the NiFeWS alloy films and all the electroplated films were exhibited Nano crystalline structure. The VSM results demonstrated that the coercivity of the nano crystalline NiFeWS films reduced with increasing the bath temperature and saturation magnetization increased with increasing the bath temperature. The hardness and adhesion of the electroplated films were also investigated. Reasons for variation in magnetic properties and structural characteristics were discussed.