I'm an undergraduate student, and my thesis topic is RFID tag antenna design and fabrication. What types of materials are used in RFID tags?
Passive low-frequency (LF) and high-frequency (HF) tag antennas are made from copper. Typically, with HF tags, the antenna is etched with acid to achieve the required thickness. With passive ultrahigh-frequency (UHF) transponders, the same technique can also be used, or you can print antennas with conductive inks or use aluminum.
Typically, companies design antennas for a particular purpose. A small antenna might be developed for use on a bottle of pharmaceuticals, whereas a larger tag might be created for pallets. Some tags are designed to be orientation-insensitive, while others are designed for situations in which a tag is always aligned in a certain way to a reader antenna.
Once a tag is designed, a prototype is created, and is then attached to a chip and tested. If the antenna works as designed, it is manufactured in large quantities. Different companies utilize different techniques. Printing machines could be used to print antennas on large reels of plastic substrate, and the antennas can later be attached. I have seen lasers used to cut thin sheets of aluminum into antenna shapes. I have also witnessed some systems in which the antenna's shape is painted with a chemical that causes copper molecules to accumulate on the substrate—though to my knowledge, this technique is not currently being used in production.
—Mark Roberti, Founder and Editor, RFID Journal
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