Mechanical characterization of electroplated nickel-iron

In this paper we present results of the mechanical characterization of electroplated nickel-iron (permalloy). The investigated plating bath is commonly used for MEMS applications, but no detailed mechanical characterization has been performed before. The following properties were investigated: residual stress, plane strain modulus, coefficient of linear thermal expansion (CTE) and mass density. The residual stress and plane strain modulus were derived from load-deflection measurements on long rectangular membranes. The CTE was extracted using the wafer curvature method. To obtain homogeneously thick electroplated films, the influence of the seed layer thickness on the current density distribution was investigated theoretically.