Fabrication of a Flexible RFID Antenna by Using the Novel Environmentally Friendly Additive Process

The fabrication of flexible antennas for RFID applications can be divided into subtractive and additive methods. In this study, a low-cost additive method is proposed, which involves printing aluminum paste and utilizing a galvanic replacement reaction. Through a galvanic replacement process, copper sulfate waste effluent was employed to convert the aluminum electrode into a highly conductive copper electrode. The physical characteristics of the Cu electrode, such as surface flatness, thickness, and Al-Cu conversion ratio, were studied. The Cu electrode, produced using an innovative additive technique at a temperature of 75°C for 15 minutes, exhibits the lowest resistivity of 5.89 × 10–8 Ωm. This resistivity is comparable to that of a commercial silver thick film electrode, making it suitable for use in manufacturing RFID antennas for RFID module applications. With an S11 of −40 dB at 1.26 GHz, a maximum gain of 2.87 dBi, a maximum efficiency of 53.63%, and a reading distance of 9 meters, the RFID module demonstrates impressive performance. The reading distance of an RFID module with a copper foil antenna is longer (8.5 meters).