The Exploitation of Polymer Thick Films in Printing Passive UHF RFID Dipole Tag Antennas on Challenging Substrates

The main objective of this thesis was to study the usability of electrically conductive polymer thick film (PTF) inks and non-traditional substrate materials in passive Ultra High Frequency (UHF) radio frequency identification (RFID) tag antenna manufactur-ing. An important part of the work was to develop new applications for printed tags. The effect of the manufacturing method and the materials’ electrical characteristics on tag performance was also investigated. In recent years the use of radio frequency identification has become increasingly popular since it has many advantages over other identification systems. The integration of electronics, such as RFID tags, in different products is becoming more widespread with the growing need for greater functionality in products. With traditional electronic mass production techniques such as etching, the integration may not be technically or eco-nomically feasible. Printing, on the other hand, is a simple additive method which is suitable for mass production. Material loss and the use of chemicals are substantially less than in etching, and printing can also be performed on a variety of materials. Although printing is a promising tag antenna manufacturing method, the printed tag ma-terials are very different from those used in etched tags. This is challenging since the materials play a crucial role in tag functioning and their electrical properties are relatively unknown. In addition, the cost of an RFID tag is still too high for item level tracking. The price must decrease further and new applications must be found in order to gain maximum benefit from this technology. Rather than focusing on the reduction of tag costs, this thesis deals with the opportunities that novel materials and manufacturing methods offer. The thesis consists of an introduction to the passive UHF RFID system, tag antenna per-formance, tag manufacturing and materials together with 9 publications. The publica-tions present in detail the effect of the manufacturing method, the conductor material and the substrate effect on tag performance. The applications of printed tags are investi-gated through case studies. The results obtained showed that competitive tags can be manufactured by printing, provided that the materials and manufacturing method are taken into account at the de-sign stage. Indeed, the design process should be regarded as an integral part of the man-ufacturing process. The use of PTF conductors, printing methods and non-traditional substrate materials facilitate the development of new applications and activities that could not be realised using traditional tag manufacturing and materials. The novel materials enable applica-tions in which the printed tags are used for other purposes than product identification, such as tag-based sensing. This enhances the use of printable electronics as well as RFID technology