Photo curable resin for 3D printed conductive structures

In this study, a new resin formulation method was developed to fabricate 3D printed conductive structures via digital light processing (DLP) 3D printing technology. Metal fillers, such as silver-coated copper flakes (AgCu) and silver nanoparticles (AgNP), were tested for conductive resin formulation. With low UV shielding and printing derivation, AgCu was selected as the conductive filler, and mixed with a photo curable acrylic resin. To resolve the sedimentation problem of metal fillers, carbon nanotubes (CNT) were added as a thickening agent to provide a supportive network to stop the metal fillers from settling. With the CNT addition, AgCu up to 70 wt% can be well dispersed in the acrylic resin with both fluidity and suspension stability. The resin can be printed into 3D metal circuitry structures with a conductivity up to 1000 S/cm without sintering. Multi-material stereolithography was also performed to produce conductive circuitry within insulation materials. The sectional view showed great connections between multiple layers of printed conductive tracks. Through-hole vias and blind vias were also built with great quality to demonstrate the capability of this conductive resin formulation.