A new method for mass fabrication of metallic microstructures

Abstract

 This paper reports on a new method for the production of metallic microstructures with high aspect ratios that combines the advantages of injection moulding with the high precision replication of surfaces by galvanic and electroless metal deposition. LIGA made moulding tools are used to produce plastic “lost forms”, which are partially metallized by a silver cluster beam of high directionality to achieve electrical conductivity. For structures with an interconnected Ag layer at the bottom, galvanic metal deposition is used to form massive microstructures without voids. For isolated structures where contacting is not possible, chemical deposition was used for metal build-up starting from the metallized areas. However, massive electroless deposition beyond about 3 μm was not yet possible due to problems with internal stress in the deposited metal layer that cause delamination from the template. This stress must be reduced by appropriate modifications of the electrolyte.