Differentiation Features of RFID Systems - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 13

Figure 2.2 Different construction formats of disk transponders. Right, transponder coil and
chip prior to fitting in housing; left, different construction formats of reader antennas (reproduced
by permission of Deister Electronic, Barsinghausen)
2.2.2 Glass housing
Glass transponders (Figure 2.3) have been developed that can be injected under the
skin of an animal for identification purposes (see Chapter 13).
Glass tubes of just 12 - 32 mm contain a microchip mounted upon a carrier (PCB) and
a chip capacitor to smooth the supply current obtained. The transponder coil incorpo-
rates wire of just 0.03 mm thickness wound onto a ferrite core. The internal components
are embedded in a soft adhesive to achieve mechanical stability (Figure 2.4).
2.2.3 Plastic housing
The plastic housing ( plastic package , PP) was developed for applications involving
particularly high mechanical demands. This housing can easily be integrated into other
products, for example into car keys for electronic immobilisation systems (Figure 2.5).
The wedge made of moulding substance (IC casting compound) contains almost the
same components as the glass transponder, but its longer coil gives it a greater func-
tional range (Figure 2.6). Further advantages are its ability to accept larger microchips
and its greater tolerance to mechanical vibrations, which is required by the automo-
tive industry, for example. The PP transponder has proved completely satisfactory
with regard to other quality requirements, such as temperature cycles or fall tests
(Bruhnke, 1996).