Electrodeposition of polyurethane adhesive for MEMS application

This paper presents a polymer electrodeposition process to prepare micro-size adhesive on electrically conductive substrates, and demonstrates its application for microelectromechanical systems (MEMS). UV-curable polyurethane latex was first formulated for cathodic electrodeposition process. Polyurethane was then conformally coated onto the conductive substrates by electrodeposition of polyurethane aqueous latex at 25 V for 1 minute. The coated polyurethane films is adherent, as a result it can be used as adhesive to bond other microstructures. The polyurethane adhesive can be further solidified by UV radiation for 2 minutes. Photolithography was used to pattern the conductive substrates with photoresist layer, which help to localize the polymer electrodeposition at specific surface locations. The deposited adhesive volume is able to be controlled in the magnitude of 10 femtoliters by adjusting the pattern size and the electrodeposition time. The electrodeposited polyurethane adhesive is useful for MEMS bonding.