RFID Antenna Ink Technology: MHz, Paper, The Future is Here

Imagine walking into your local supermarket, browsing the isles picking and choosing products and placing each one into your cart. Once you have finished you simply stroll out the front door, no check stand, no security guard – no guilt. Your items were instantly rung up for you as you passed by the stores sensors while you exited the store. Master Card, Visa, or your bank is notified of the charge and an email of your receipt is sent to your personal account. Now apply this scenario to every store you visit. Getting gas, buying a computer, getting new shoes, or even new clothes. Just wear them out and your items are charged as you exit the store. Each of these scenarios is made possible using RFID technology.

RFID or Radio Frequency Identification has been around for almost 90 years. Originally designed for espionage and covert operations for various governments; the concept for this technology has recently been found to have more applications than once considered (Wikipedia). Like all new technologies it took some time to work out the bugs, but in the very near future it will transparently become part of our everyday lives.

RFID Tags are made up of several simple components to give the product or wearer a unique identity. Tags are made up of a silicon chip, antenna, and sometimes a battery or source of power. The antenna receives a signal that passes though its silicon computer chip and transmits its unique signal back to a reading system (Wikipedia). The reading area would be an electromagnetic field that when entered, activated the tags and read each items unique signature.

In order to make all of this work, RFID tags will eventually become part of the product or product packaging we are purchasing in some way. According to Frank Romano, packaging currently represents the largest portion of the printing industry. This means that if tags for RFID will be on everything we buy, it would be cost effective to print these components on packages.

There are several companies that have developed RFID strategies and products that have been designed to be integrated into high and low volume print workflows.

Conductive Ink Method

Flint Ink, in Michigan has created a conductive-ink company called Precisia who’s sole purpose is to develop effective RFID printing methods. The combination of Flint and Precisia represent a leap in mass production techniques. Flint Ink is a member of the Auto-ID society and is working in combination with several other companies that specialize in screen-printing, flexography, gravure, and offset lithography to test their conductive ink products. (Tracking 2004) It is only a matter of research and development time and soon these methods will become improved to the point where they can become part of high-speed workflows. (Tracking 2004)

XINK has developed a type of water based conductive ink they call “paper-wire.” It was developed by their electrical engineers need to put tracking on pharmaceutical bottles. It is printed using flexographic methods and uses Instacure technologies. (XINK, 2006) This means that it dries instantly on press at high speeds, fully cures without drying equipment, prints on a range of substrates, features excellent conductivity due to high silver content, and has an extended shelf life. (XINK, 2006) These tags have an 85-100% read range of a copper antenna at a fraction of the cost. Most copper tags can be read at 3-4 meters while these can be read at close to six. XINK claims to have a stable formula ready for any flexo press but offer to tune the ink for your needs so you get the best adhesion. (XINK, 2006)

Powering a Tag

Power Paper, based in Israel is developing PowerID, calling it the next generation of RFID technologies. “Power Paper’s core technology is an innovative process that enables the printing of caseless, thin, flexible, and environment friendly energy cells on a polymer film substrate by means of a simple mass-printing technology and proprietary inks.” (Power Printing 2004)

Motorola has created BiStatix, another type of RFID technology. Silicon chips are embedded on the labels themselves able to store up to 900 user bits of information, or one hundred and twenty characters. (TechTV, 2004) The BiStatix technology is designed so it can be implemented into just about any printing method. Printing the labels onto packages would happen in separate units after 4-color process in four separate layers. The extra units lay down four more layers for the BiStatix ID. Contained in each layer are transistors, gate, dielectric, source, and active layer. Adding these extra layers could potentially be completed running at a few thousand sheets per hour.

Power Paper and Motorola created a partnership to develop what they are calling the Printalix system. This system will integrate Motorola’s conductive ink labeling system with Power Paper as its power source. The tags can then be adhered to any substrate with high readability and excellent durability.

Printing the Antenna Structure

In order to print an effective antenna on a package it must be flexible, durable, tamper-proof, cost effective, and have an almost perfect readability rate. There are a few different methods to print an antenna. Screen-printing it needs to have special conductive inks that easily bond with the substrate. Sun Chemicals is developing a metal printing process in conjunction with another company who owns several patents on printing systems. XINK has designed a method using electroplating that is up to 4 times faster and 60-75% cheaper than etching copper.

In order to effectively print an RFID antenna additive screen-printing using silver ink has proven to be both cost effective and secure. Previously popular were subtractive etching methods out of copper. This could potentially require toxic chemicals and take time. The antenna screen printed directly onto a substrate gets absorbed into the fibers of the paper and is extremely difficult to tamper with. (Sure, ASK) As silver inks are further developed for this purpose it is reasonable that antenna reception and efficiency will improve. Since screen printing is a tested process the application of the antenna to products such as, tickets, passports, smart cards, and other flexible items would be cost effective. The RFID that has been screen printed is also virtually impossible to tamper with. Attempts to tamper with the antenna could potentially damage it or break the chip-antenna connector. (Sure, ASK)

Sun Chemical has recently been developing a method for printing an antenna structure for an RFID tag. Sun Chemicals, the largest supplier of printing inks and pigments that they are working with a company called QinetiQ (pronounced kinetic) to produce a low-cost high-volume security and tracking tags where a metal pattern is needed. The tags will also be designed for many other applications as well. QinetiQ owns several patents on commercial metal printing processes on selective surfaces. Desired patterns are printed on both flexible and inflexible substrates then “growing” pure fully densified metal only where required by immersion in chemical baths. (Sun Chemical 2005) The process is currently being tested in the U.K. to prove it is a viable option for high and low volume workflows.

Meco, based out of the Netherlands, has also recently developed a method for printing antennas that reduced the cost by 60-75%. Expensive silver ink is laid down then electroplated with copper resulting in an antenna that is about 5 microns thick. Fully etched copper antennas cost between $9.48 and $11.85 per square meter as opposed to $7.11 for the electroplated. (Collins 2005) The cost has been significantly reduced due to using less silver and copper. "Printed antennas can require between 25 to 35 microns of silver ink. That's very high compared with the seed layer required with plating," says Van Nunen, Meco Engineer. The thinner antenna can be produced four times faster than etched copper versions. These electroplated antennas could be produced at a rate of 7.5 million per month.

There is still much development that will need to go into making RFID part of our everyday lives. Creating solid methods for printing these tags will become a highly competitive part of the print and packaging industry. On the other hand it will also prove to be highly profitable as well. Those who are able to develop a standardization method, like barcodes, will be the frontrunners of making this an everyday reality. We have already seen several companies come into this part of the industry and change course. The RFIDs of the future I believe will become transparent and virtually invisible. Security will become harder and harder to defeat as more and more data is stored on the chip of the tag. Package designers will make them harder and harder to find while they shrink with each generational version. This will create a greater canvas for package designers and we will certainly see an increase in fancy packaging. Soon your shopping cart will be filled with all kinds of great looking goodies, and you will be able to stroll out the front door, RFID tags read and totaled, and debited all before you reach your car – if we are still in cars.