NANOSTRUCTURED METALS FOR ENHANCED PERFORMANCE OF LIGA COMPONENTS

摘要

This paper addresses the issues of performance variability and reliability concerns frequently encountered with metallic microsystem components produced by electrodeposition methods such as LIGA. Experimental results will be presented which demonstrate that microsystem components produced by conventional electrodeposition approaches show relatively low overall hardness and considerable variations of Young's modulus and hardness throughout their cross section. These undesirable properties are traced back to ⅰ) the microstructure of the deposits which is characterized by grain size gradients resulting from the fine grained to columnar structure transition and ⅱ) the relatively large grain size in comparison to the overall component size. In past efforts both post deposition recrystallization annealing and texture control during the electroplating process have been used in attempts to alleviate these concerns, however only with limited success. In this paper, we present a new approach which essentially involves the modification of the electrodeposition process to produce fully dense nanostructured deposits throughout the entire cross section of the component without transition from fine to large grained columnar structure. Results will be presented for such components which show ⅰ) uniform hardness and Young's modulus in cross section and ⅱ) significant enhancements in hardness and other important performance indicators such as specific strength and elastic energy storage capacity.