There is an enormous and growing market for printed conductive patterns and the most obvious one is in Radio Frequency
which is finally taking off after 60 years in the doldrums with only 1.8 billion tags having been sold up to 2005. Now Texas Instruments
, the largest supplier, has announced that it is approaching 500 million tags sold despite some of the largest recent orders having gone to Symbol Technologies
because they have bought startup Matrics that landed those orders last year. Symbol now looks set to supply 250 million tags just for two airports - McCarran Las Vegas and Hong Kong International Airport. And we all know that orders for billions of tags yearly for pallets and cases await the industry once the battles over standards and intellectual property and the technical problems are resolved for these Electronic Product Code EPC tags. They will be for consumer goods
and military supply chains.
Little wonder then that the first port of call for those with a new way putting down conductive patterns is RFID - and specifically RFID antennas. After all, the leading contenders for RFID tag design are ones based on silicon chips and what will, hopefully, be cheaper in the long run - Thin Film Transistor
Circuits TFTCs and Surface Acoustic Wave SAW
tags. All need an antenna. Other designs of "chipless" RFID tag do not need an antenna but they cannot yet meet the EPC-based specifications demanded by retailers, the military and so on so they are also-rans for the big time.
That means that if we replace trillions of barcodes we shall need trillions of antennas yearly. In the main, they will be required to work at 13.56 MHz, the most popular frequency so far with over one billion such tags working satisfactorily in the field, or at the relatively unproven frequency band of UHF
- around 800 to 920 MHz depending on territorial jurisdiction - with only a few million working in the field. At 13.56 MHz the antenna must be a coil of precise dimensions and of high conductivity. At UHF more resistive, more crudely defined shapes suffice. IDTechEx believes that the necessary price of finished, protected tags at the trillion a year level must be one cent or even less, so that antenna must definitely be printed.
Enter the contenders for printed RFID antennas. The precious metal silver is much in evidence, initially as a thick layer formed by sheet or rotary screen printing
to compensate for the poor connection between silver particles in the polymer suspension. But recently we have seen many finer silver formulations suitable for high speed printing processes
such as offset litho, gravure
and flexo and the race is on for inks that have no silver but deposit at high speed to form low temperature curing (ie cheap substrate) patterns of adequate conductance. It can be presumed that all the leading manufacturers of electronic inks in the world are chasing this one. However, plenty of other contestants for the highest volume antennas believe that wet processes such as electroless deposition can get there. The result is that putative ink and process designers come and go every year. So is there an alternative approach that is less Kamikase, especially for the small man and woman? The answer is yes.
Imaginative companies such as T-ink
, Birch Point and Power Paper
are using their capabilities in conductive patterning outside of RFID in the main. They design totally new products such as the electronic skin patch that puts down a tattoo that lasts four months - something not previously possible - or the cost-effective electronic Cluedo game or the interactive MacDonald's place mat. They have the parcel that detects and records tampering and much more besides.
In some applications graphite patterns suffice which are near useless in RFID. So the message has to be - if you are one of the many offering a new way of putting thin conductive films onto almost anything, think of non-RFID applications first and preferably in imaginative new markets. If you lack imagination, team up with a company that does. IDTechEx can lead you there.