Printed flexible RFID label with temperature and humidity sensors

The present work consists of developing a flexible RFID label which integrates CMOS humidity and temperature sensors silicon chip using large-area printing processes and advanced chip-on-flex assembly processes. We report on the designing, elaboration and testing of the smart flexible RFID labels. The approach consists of the technology transfer of a UHF RFID Tag from classic rigid-PCB to a flexible polymeric substrate by printing techniques. The fabrication of antenna and PCB on flexible, plastic substrates (PET) was performed by means of roto-screen printing. The latter allows a high thermal transfer to the printed material, which is necessary for its sintering, while preserving the delicate substrate. Cost-effective and low temperature methods are also developed for the assembling of the silicon chip: methods involving conductive glues and anisotropic conductive adhesive or film and chips placement; fixation and electrical connections are done using a chip bonder and printing/dispensing or lamination of the conductive and adhesives materials