Evaluation of Elastoplastic Properties of Anisotropic LIGA Nickel Films

Most current MEMS are using LIGA nickel films as their structural material. In order to design and produce MEMS devices accurately, it is very important to know the mechanical properties of LIGA films. However, the mechanical property evaluation for LIGA films is difficult, because LIGA films have anisotropic mechanical properties due to their microstructures and the specimens to be used in the mechanical property evaluation testing are too small to handle easily. Consequently, the evaluation methods for LIGA films have not been standardized. In this study, the Young's modulus and yield stress of LIGA nickel films are evaluated by a series of spherical indentation testing and elastoplastic analysis. Then, the effect of non-equilibrium microstructures of LIGA films on anisotropic mechanical properties is discussed.