Injection Molding of Nanoscale Features

Jun S. Lee, Plastics Engineering; Joey L. Mead, Plastics Engineering and Carol M. F. Barry, Plastics Engineering

Optical grade polycarbonate and biomedical grade thermoplastic polyurethane (TPU) were used for injection molding with silicon tooling.  Micro and sub-micro features with a range of aspect ratio were prepared by lithography.  Atomic force, confocal optical, and scanning electron microscopy were used for characterization.  The flexible TPU resulted in superior replication and ejection than polycarbonate; replication was enhanced by higher mold temperatures and injection velocities; and antistiction coatings on the tooling significantly improved replication quality under moderate injection molding conditions.  The replication result of TPU reached to 92%.