A novel method for the curing of metal particle loaded conductive inks and pastes

The emerging technology of printed microelectronics involving the use of conductive inks in conjunction with standard printing techniques offers a fast and low waste method for creating microelectronics compared with standard manufacturing processes. A clear path to the creation of flexible electronics is present due to the ease of printing on flexible substrates. Moreover, creation of novel 3D structural electronics is possible via the integration of printing technologies and additive manufacturing (AM) techniques. A key obstacle to the manufacturing of flexible and structural electronics comes from the temperature restrictions imposed by the substrates, which are typically polymeric. This hindrance has the effect of limiting the thermal cure cycles necessary to create the maximum electrical performance of conductive traces printed with conductive ink, which must be thermally cured. Whether the ink has micro-scale conductive particles, nano-scale conductive particles, or is organometallic in nature, all conductive inks need some sort of thermal curing to perform properly. The research presented in this dissertation entails the development of a curing technique which creates the optimal electrical performance in conductive traces created from conductive ink on both flexible and 3D polymeric substrates. The utilization of ohmic heating in conjunction with and in lieu of thermal curing is shown to decrease the resistivity of conductive traces printed form conductive inks and pastes. Microstructural characterization was performed on successful and unsuccessful (electrically failed) specimens. A process characterization of the creation of a via/interconnect system in a 3D freeform was made and involved electrical characterization and printable conductor selection. Initial research involving electrical and microstructural characterization of the thermal curing process is presented along with novel findings showing the impact of inkjet printing procedure on the resulting electrical resistivity. Also, a failure analysis of a component from a direct write equipment set was made