Performance comparison of inkjet and thermal transfer printed passive ultra-high-frequency radio-frequency identification tags

The authors compare the maximum read range of passive ultra-high-frequency radio-frequency identification tags that have been produced using different metal printing techniques, specifically inkjet printing and thermal transfer printing (TTP). They used the same substrate (THERMLfilm), antenna designs and electronic circuitry in their comparison so as to isolate the effect of the metal printing. Owing to the high metal conductivity, the thermal transfer printed tags printed with copper (Cu) film performed as well or better than the inkjet printed tags printed with silver ink, even when they changed the inkjet printed tags to a Kapton substrate that is better suited to inkjet printing. The aluminium (Al) thermal transfer printed tags had up to 33% less read range than Cu thermal transfer printed tags. TTP needs no sintering, and provides an attractive alternative low-cost fabrication method. Characterisation of the printed traces by both methods reveals that the printing techniques achieve similar surface roughness. The achieved conductivities for TTP on THERMLfilm were better than for inkjet. The best measured read range for TTP was 10.6 m. Across the different tag designs, the measured read ranges were 15-60% (1-10%) better for thermal printing, compared with inkjet printing on THERMLfilm (Kapton)