Differentiation Features of RFID Systems - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 20

Figure 2.15 A smart label primarily consists of a thin paper or plastic foil onto which the
transponder coil and transponder chip can be applied (Tag-It Transponder, reproduced by per-
mission of Texas Instruments, Friesing)

An obvious step down the route of miniaturisation is the integration of the coil onto
the chip ( coil-on-chip ) (Figure 2.16). This is made possible by a special microgalvanic
process that can take place on a normal CMOS wafer. The coil is placed directly onto
the isolator of the silicon chip in the form of a planar (single layer) spiral arrangement
and contacted to the circuit below by means of conventional openings in the passivation
layer (Jurisch, 1995, 1998). The conductor track widths achieved lie in the range of
5-10 µ m with a layer thickness of 15 - 30 µ m. A final passivation onto a polyamide
base is performed to guarantee the mechanical loading capacity of the contactless
memory module based upon coil-on-chip technology.
The size of the silicon chip, and thus the entire transponder, is just 3 mm 3mm.

The transponders are frequently embedded in a plastic shell for convenience and at

×

6mm × 1 . 5 mm are among the smallest RFID transponders available on the market.

2.2.10 Other formats

In addition to these main designs, several application-specific special designs are also
manufactured. Examples are the 'racing pigeon transponder' or the 'champion chip'
for sports timing. Transponders can be incorporated into any design required by the
customer. The preferred options are glass or PP transponders, which are then processed
further to obtain the ultimate form.