Effect of pH Values on the Magnetic Properties of Electroplated NiFe Layers

The NiFe alloy is a good candidate for magnetic sensing applications due to its high magnetic permeability. For electroplated NiFe layers, the composition of the nickel and iron will change as the pH value of the plating solution changes. This is partly due to the different deposition rates for iron and nickel at different pH values. The pH values of the plating solution can be increased by adding potassium hydroxide or decreased by adding hydrochloric acid. In this study, the effects of the magneto-impedance of the plated NiFe layers as a function of the pH value of the plating solution are investigated. The results show that the higher the pH value of the plating solution, the higher the Fe content in the deposited alloy. For optimum magnetic properties with high magneto-impedance (MI) ratios, the composition of the NiFe alloy should be close to 80% nickel and 20% iron.