Low Temperature Direct-Write Fabrication of Radio Frequency Identification Circuit and Antenna Structures on Polymer Substrates

Abstract

We report the direct-write fabrication of electric circuits on polyethylene terephthalate (PET) substrates by a low temperature technique. To demonstrate the utility of the concept, Radio Frequency Identification Circuit and Antenna Structures were fabricated on polyethylene terephthalate (PET), using a 300 dpi drop-on-demand HP DeskJet system. First, each substrate was prepared by low frequency atmospheric plasma etching, followed by tin (II) chloride treatment to enhance wetting. Then a catalytic silver seed layer pattern was bubble-jet printed onto the surface. Finally, the substrate was developed in a copper electroless plating bath for 10 min. to yield a 2.5 µm copper film with a sheet resistance of 3.4 Ωsq. The as-deposited film was shiny with a surface roughness of less than 8.7nm, which is about 0.35% of the film thickness. The films were characterized by SEM, EDX, profilometry, optical microscopy, and four-point probe resistivity measurement. This technology may be adapted for the direct-write fabrication of antenna structures for communication devices and space science applications.