Fabrication of built-in copper microstructures on epoxy resin

This paper describes a simple and effective method to fabricate built-in copper microstructures on a polymer substrate. Our method uses a micropatterned amino (NH₂)-terminated self-assembled monolayer (SAM) as a template to fabricate patterned copper (Cu) film for transfer to an epoxy resin. Cu microstructures were first formed on a photolithographically micropatterned NH₂-SAM-covered SiO₂/Si substrate through conventional electroless plating, in which Cu deposition proceeded selectively on the NH ₂-terminated areas while the photo-irradiated areas remained free of copper deposits. Next, epoxy glue (resin) was poured into a Teflon® O-ring placed so as to surround the Cu-micropatterned substrate. Finally, after the resin completely hardened, it was removed from the substrate. Due to the weak adhesion between the Cu film and the NH₂-terminated surface, the area-selectively deposited Cu film could be readily peeled off and removed from the SiO₂/Si substrate and thus transferred to the resin surface. Through this technique, high-resolution 10-μm-wide Cu microstructures were successfully fabricated on the epoxy resin surface. These embedded Cu microstructures were tightly adhered to the resin. No peeling of the copper structures was observed in a Scotch® tape peeling test.