Development of Large Area Electrodeposition Process for Stress Free Electroforming Mold

Abstract

Electroforming is a highly specialized process for the fabrication of metal parts using electrodeposition. It is known that nearly all electrodeposited nickel alloys possess higher mechanical hardness and tensile strength compared to the pure nickel metal. Cobalt-Nickel (CoNi) alloys have been investigated as important engineering materials for several decades because of their unique properties, such as high strength, good wear resistance, and heat-conductive and electrocatalytic activity. Additionally, the use of CoNi alloys has been extended to the production of 3-dimensional, complex-shaped finished components by the electroforming technique. To fabricate electroforming mold by using CoNi alloy, the stress in the electrodeposits is a very important factor. In this study, CoNi alloys were electrodeposited from cobalt-nickel chloride electrolyte to investigate the influence of Co and stress reducer concentration, and flow velocity of plating solution on CoNi film stress. Finally, 140 mm CoNi alloy stamp for NIL was fabricated from a nano Si mother mold by using stress free electroforming method. The duplication of a CoNi alloy stamp is possible without the consumption of a costly Si mother stamp. Duplicated patterns on CoNi alloy stamp were compared with those of Si mother mold by using field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM).