Printing Electronic Circuitry with Copper Solutions

1. Printing Electronic Circuitry with Copper Solutions Investigators: C. M. Megaridis, Mechanical and Industrial Engineering; C. Takoudis, Bioengineering; J. Belot, Univ. Nebraska-Lincoln; J. McAndrew, Air Liquide, Inc. Prime Grant Support: Air Liquide • Patterned metal films are essential to a wide range of applications ranging from printed circuits, to thin-film displays and electrodes in biomedical implants • Inkjet printing has environmental benefits while offering flexibility, cost savings, and scalability to large area substrates • Initial focus on Copper due to its very low resistivity. Future extension to bio-compatible metals • Homogeneous metal inks eliminate obstacles encountered while using nanoparticle ink suspensions • Synthesis of metal compounds as primary ingredients of homogeneous inks • Ink physical and rheological properties (viscosity, surface tension) optimized for printability • Printing tests for optimal line formation; thermal treatment to reduce the deposit to pure metal; final product testing/evaluation • X-ray photoelectron spectroscopy and electron microscopy used to characterize deposit chemical composition and surface quality • Candidate organocopper compounds and solvents have been identified, providing facile decomposition to metallic copper (removal of ligands + reduction of Cu2+to Cu0), and copper content > 10% wt. • Copper lines printed in the laboratory indicate that homogeneous solutions of organocopper compounds can be developed with suitable properties for ink-jet printing • Research has the potential to catapult progress in metal ink fabrication and in-situ formation of metallic lines with feature size in the 10-100 m range