Wednesday, August 20, 2014

RFID inlays

RFID inlays are composed of an IC (Integrated Circuit, Chip) and a Dipole antenna. To attach the antenna to the IC we commonly use a strap. 

Antennas can be made of silver, aluminum or copper, with each material producing very specific read and write characteristics because of the different chemical properties. While there are some more exotic materials sometimes used for antennas they are considerably more expensive to produce and very vertical application specific. Generally a copper antenna is slightly more expensive that aluminum or silver but is more conductive and usually provides a longer distance read capability.

Just as there is a very wide variety of IC's for inlays, there is also a very wide variety of antennas ranging from very small - Dot, Button, Paperclips through DogBone, Hammer, Crab, Radar, Satillite, Squiggle, Mini Squiggle, Torpedo, Xcaliber, Web and Frog sizes - each inlay usually has a specific name to identify it.
Size and shape of the antenna determines the read and write distance and speed characteristics. 

Inlays come on rolls ready to package/ecapsulate into finished tags. Each roll contains between 5,000 and 20,000 inlays and the automated equipment to make a tag must be set up for each roll type so a production run of 5,000 tags can easily be a single roll or a 1/4 of a roll. Most converters operate JIT facilities meaning that stock or inventory is not kept since there are so many varieties of inlays that can be used to produce a single tag. 

RFID inlays can be either "wet" or "dry" .
Wet inlays are inlays that have an adhesive backing with a clear or colored topsurface of PVC,PET or paper, the PVC or PET wet inlays are commonly used to make "RFID Labels" where the inlay is placed on the back of the label with the adhesive side away from the label side so that the label has continuous adhesive. PLacement of the wet inlay on the label is very specific to each RFID printer in order to be programmed correctly by the printer and also to minimize the risk of damaging the RFID inlay while in the printer.
Dry inlays are inlays that are attached to the substrate backing material commonly called the web. 

The small sample above depicts actual HF and UHF inlays at approximately actual size. Gen 2 inlays range in size from 7mm dia - 0.276 inches(Microdot) through 76.2 x 76.2 - 3 inches by 3 inches (Frog), to antenna designs that are aver 150 mm - almost 6 inches long.