Optimization of Mechanical and Magnetic Properties in High, Electroplated Co–Fe-Flux Guides

Soft magnetic materials are widely used as flux guides in sensor and actuator applications. Iron-rich binary Co-Fe alloys offer high saturation flux densities B_s up to 2.4 T, which make them suitable as a flux guide material for high field applications. Their fabrication by electrodeposition has been examined to a large extent these last few years. It is well known that the high values of B_s are paid for with high film stress and vulnerability to corrosion. Extensive studies of electroplated films with thicknesses up to 3 μm yielded a better understanding of the influence of deposition techniques and parameters not only on the magnetic properties, but also on the film stress in the deposited layer. For the design of an ultrathin, three-dimensional magnetic field sensor intended for high field applications in very small spaces, flux guides with a thickness of 20 μm are needed. This paper aims at the optimization of the deposition process of these flux guide structures relating to residual film stress, corrosion and investigates the influence on coercivity and saturation flux density.