Photopatternable Electrical Conductive Ag- SU-8 Nanocomposite for MEMS/MST

Abstract

An electrically conductive SU-8 has been formulated and can be used to build micro-components for MEMS, microfluidics and packaging applications. SU-8 is an insulating near -UV negative-tone photoresist. An electrically conductive SU-8 has been formulated and can be used to build micro-components for MEMS, microfluidics and packaging applications. In order to enhance the electrical conductivity of SU-8, silver nanoparticles with an average diameter of 80nm were dispersed by ultrasonic agitation. The resulting nanocomposite was successfully patterned. Evolution of electrical conductivity of SU-8 as a function of weight percentage has been studied. It is observed that the conductivity increases slowly up to 2.2 wt% weight concentration. However, after this point the conductivity increases rapidly. This behavior of conductivity variation can be explained in terms of the percolation theory. At lower concentrations of silver nanoparticles, percolation paths are not set up by the nanoparticle network. As the concentration of nanoparticles in the composite increases, the percolation paths via conducting nanoparticles are set up. At this stage, the nanoparticles control the conductivity of the nanocomposite matrix.