Recently patented technology allows printing conductive metal onto non-porous substrates thereby providing applications ranging from sensors to printed circuitry. One area of particular interest is the production of RFID antennas for packages of high-value items, such as medical devices. With RFID devices on packages, they can be tracked in transit and inventoried more quickly than previously possible. The printing process can produce reels of RFID antennas where each cost less than one cent, and each can be different. The thinner the metal laid down, the faster the process runs and the lower the cost. Research shows that 0.5 micron thick copper is ideal for UHF antennas and produces an ideal read-range performance.

Development on printing RFID antennas stalled because the available conductive inks used nanoparticles that required a high-temperature sintering for good conductivity. That is not ideal when the base substrate is a plastic that melts at high temperature. What's more, the inks have been extremely expensive.

The solution was found in UV cured ink. Instead of printing metal through ultra-fine nozzles, an inkjetable catalyst ink works reliably and repeatably in inkjet printing. This prints the image onto the plastic part. The plastic substrate then is immersed into standard electroless-plating chemistry, which grows metal only on the preprinted pattern. The result is a low-cost, fast process that lays down a conductive metal using standard industrial inkjet heads.

Metal printing can be used in applications where highly conductive tracks are needed on plastic materials. A few include printed circuitry, RFID tags and smart cards, edge connectors, and heaters.

Being a digital process means a product needs no tooling such as masks, or start-up costs. When a design needs changing, the designer adjusts a CAD file and prints it, making the process useful for short runs and prototypes. What's more, low cost makes the process also applicable for low volume runs. A reel-to-reel printer developed for these tasks, MetalJet 6000, can lay down images on a web about 11-in. wide at a speed of 100 fpm giving it a capability of over 1 billion antennas per year.

Another plus for the inkjet technology is that because it is noncontacting, it can apply conductive circuitry onto 3D-molded parts. These can be run under the inkjet print heads, which print a pattern onto the top or sides of a part. With more complex geometry, a robot can rotate the part to maintain proper distance from the print head to give complete coverage. This could be most useful printing RFID antenna on medical parts.

The company has also found a way to place a processor on a surface and then print an antenna and connection to the chip at one time. This patented technology, called Print2Chip, has potential to further reduce the overall tag cost.