Soft Magnetic Properties of Electrodeposited Fe-Ni Films Prepared in Citric Acid Based Bath

Electrodeposited Fe-Ni films are widely used in device applications. However, there is a growing awareness of the toxicity of the plating bath containing boric acid. In order to avoid boric acid in the deposition process, we have employed a citric acid based bath for electrodeposition of Fe-Ni films and investigated the effect of the acid content in the bath on the structural and magnetic properties of the deposited films. It is found that the Fe content of the film depends largely on the acid concentration and low coercivity values of less than 30 A/m are realized when the Fe content of the film is around 22 at.%. This magnetic softness is attainable in a wide film thickness range between 20 and 120 μm. Our process exhibits a relatively high cathode efficiency of above 55%. Furthermore, a high deposition rate of 170 μm/h is obtained without sacrificing the magnetic softness of the film by increasing the current density during the deposition. From these results, we conclude that the citric acid based bath is an environmentally friendlier plating bath ideal for mass-production of magnetically soft Fe-Ni films.