Investigation of a Biocompatible Polyurethane-Based Isotropically Conductive Adhesive for UHF RFID Tag Antennas

As a candidate dispersant for silver-based isotropically conductive adhesives (ICAs), polyurethane (PU) is an environmentally benign material that can withstand a high deformation rate and that exhibits excellent reliability. In this work we investigated methyl ethyl ketoxime (MEKO) blocked isophorone diisocyanate (IPDI) and MEKO blocked hexamethylene diisocyanate (HDI) as dispersant materials, and we characterize the electrical conductivity, mechanical properties, and reliability of these PU-based ICAs with silver-flake filler content ranging from 30 wt.% to 75 wt.%. Results of temperature–humidity testing (THT) at 85°C and 85% relative humidity (RH) and thermal cycling testing (TCT) at −40°C to 125°C show that these ICAs have excellent reliability. Our experimental results suggest that the MEKO blocked PU dispersants are suitable for preparing ultralow-cost, flexible, high-performance ICAs for printing antennas for ultrahigh-frequency radiofrequency identification (RFID) tags. These tags can potentially be used for identifying washable items and food packaging.