International Journal of Materials Science and Applications 2014; 3(3): 84-87 Published online May 20, 2014 (http://www.sciencepublishinggroup.com/j/ijmsa) doi: 10.11648/j.ijmsa.20140303.12 Low temperature direct-write fabrication of radio frequency identification circuit and antenna structures on polymer substrates Alu, Noble O. * , Oberafo, Anthony A., Iwok, Unwana U., Adama, Kenneth K., Imalerio, Thomas I. Physics Advanced Laboratory, Sheda Science & Technology Complex, P. M. B. 181, Garki - Abuja Email address: noble.alu@gmail.com (N. O. Alu) To cite this article: Alu, Noble O., Oberafo, Anthony A., Iwok, Unwana U., Adama, Kenneth K., Imalerio, Thomas I.. Low Temperature Direct-Write Fabrication of Radio Frequency Identification Circuit and Antenna Structures on Polymer Substrates. International Journal of Materials Science and Applications. Vol. 3, No. 3, 2014, pp. 84-87. doi: 10.11648/j.ijmsa.20140303.12 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. Keywords: Direct-Write Fabrication, Silver Seed Layer, Characterization 1. Introduction The industrial standard for fabricating electric circuits is a subtractive process in which copper-clad boards are coated with a resist and, after lithography, is subsequently etched chemically to produce the circuit lines in a process which is not only expensive but also suffers from high material wastage [1]. In recent times, however, the direct-write farbrication (DWF) of electronic and optoelectronic devices have attracted much attention as it dispenses with the need for expensive lithography, vacuum processes and expensive equipment associated with the conventional process. DWF encompasses a wide range of technologies which enable the rapid farbrication of two and three-dimensional structures by the selective deposition or removal of materials in a layer by layer manner. The key technologies include nozzle dispensing processes, such as inkjet printing, transfer methods and laser systems. In this study, we have applied drop on demand ink-jet printing for the direct-write farbrication of electric circuits on polymer substrates at room temperature. In our process, silver nano-particles are inkjet-printed on a pretreated substrate and serve as the catalytic seed layer for subsequent electroless deposition of copper, thus enabling direct fabrication of electric circuits on a wide variety of substrates directly from a CAD file at low temperatures. It has been shown that the surface pretreatment step, for instance, by the introduction of self-assembled monolayers (SAM) and polyelectrolyte multilayers (PEM) is key to the successful sensitization of the substrate for subsequent electroless metal plating. Cheng et al [2] used alternating layers of cationic poly (allylamine) hydrochloride and anionic poly (acrylic acid) (PAA) to form a self-assembled polyelectrolyte multilayer, microscopic examination of such films revealed a highly porous surface that enabled highly efficient anchorage of the catalyst and resulted in the growth of coherent and adherent films of copper during subsequent electroless copper plating. We have found that simple treatment with acidic tin (II) chloride followed by dilute hydrazine solution and rapid drying was enough to sensitize the surface for subsequent deposition of a catalyst and