“Found in everything from computers, mobile phones and electronics to toys, calculators and product identification tags, conductive circuits are one of the most widely used components of consumer products,” said Steve Ludmerer, president, Parelec, Inc. “Primary applications today are in printing antennae for radio frequency identification tags, touch pads and membrane circuits and flexible circuits.”
These inks are comprised of finely dispersed particles and are used in circuit boards to produce conductive patterns on a variety of substrates. “Conductive inks are specially-prepared suspensions of finely dispersed conductive particles–most commonly silver and/or carbon–in a variety of resin systems,” said James Rohrkemper, president, Precisia LLC, Flint Ink Corporation’s new business unit devoted to conductive and advanced inks. “The inks are used to produce conductive patterns on flexible and rigid substrates. The flexo/gravure inks are water-based and the litho inks are oil-based.”
These inks are used in a variety of applications, including RFID and “smart” labels. RFID labels are comprised of a silicon chip that carries identification data and an antenna that transmits a radio frequency signal that can be detected at a distance. The chip receives and transmits the data, such as a product identification number, using the antenna. The radio signal is picked up by another source, such as a computer scanner, which then reads the information that is being transmitted. Conductive inks can be used in place of traditional coils for the antenna.
“Smart” labels are active RFID labels which can track, process and store data. Smart labels provide manufacturers and distributors with real-time visibility in inventory, and can help a manufacturer monitor conditions and locations anywhere in a supply chain system. For example, they can be used to monitor packaged foods and pharmaceuticals that must be stored and shipped at precise temperatures. A smart label using a conductive ink antenna can potentially gauge the temperature in shipment and alert a supplier to harmful shifts in temperature, according to Precisia.
This new technology is being implemented in a variety of new applications in the packaging, tag, label and ticket markets for anti-theft, tracking and tracing. It is also being used to track inventory and for management of supply chains.
“Conductive inks are used to produce conductive tracks for the manufacture of printed circuits, membrane switches or printed wiring boards (PCB, PWB) and for a wide variety of other uses such as intelligent packages, circuit components and antennae for radio frequency identification solutions,” said Mr. Rohrkemper.
RFID tags contain tiny chips that carry not only identification data, but also a radio frequency signal that can be detected at a distance. Unlike a regular bar code, the tag does not need to be seen, but can instead be automatically read via a reader antenna attached to a computer network.
As further advancements are made in the development of conductive ink and the price of this new technology goes down, industry insiders are confident that RFID tags will become even more widely used.
“RFID tags are comprised of essentially two components: a silicon chip and an antenna,” said Mr. Rohrkemper. “The chip receives and transmits the data–such as an ID number–using the antenna. Precisia has worked closely with chip developers to design special conductive inks which, when printed, can serve as the antenna. Preliminary results are very encouraging, and as the cost of RFID tags decreases from the present $.50 USD to less than $.10 USD, billions and eventually trillions of items may have these tags.”
Conductive inks offer users a number of key benefits; they are generally less expensive then the etching process for traditional electronic circuits, have low VOCs and are compatible with a wide variety of substrates.
“Traditional electronic circuits are etched in a 10-step process that requires significant capital investment and will generate hazardous acid wastes,” said Mr. Ludmerer. “Parmod VLT inks replace the etching process with a two-step ‘print and dry’ process.”
Conductive inks are compatible with a variety of blankets, plates and substrates. “Rather than specify a process for an application, we provide materials that enable our customers to utilize their current presses,” said Mr. Rohrkemper. “This is an important distinction and advantage of Precisia inks—they may be run on high-speed presses, like normal inks, and aren’t limited to slower press processes (such as screen printing) as some other conductive inks are.”
These inks have low VOCs and are considered to be environmentally-friendly. “Line resolutions of 50 microns (2 mil) are achievable with the flexo/gravure inks, and 40 microns (1 mil) with the litho inks,” said Mr. Rohrkemper. “These line resolutions allow more compact, complex and varied circuit designs. The inks have sheet resistance of up to 100 milli-ohms2 at a film thickness of approximately 8 microns. For printed resistors, ink formulations can be tuned to cover a wide range of sheet resistance (100 ohm2 – 500 ohm2) at a film thickness of 2 microns or less.”
The inks are either carbon- or silver-based, depending on the end application. “The silver inks offer longer read ranges for RFID antennae and circuit designs, whereas the carbon can be used for low-power applications,” noted Mr. Rohrkemper. “Low-power applications can include the anti-static treatment used in the protection of electronics, or instances where short read ranges are sufficient in RFID antennae.”
Packaging and Label
|Photos courtesy of Parelec.|
“The packaging and label companies have shown the most interest, because these technologies can enhance their existing product lines with ‘smart’ and active labeling, and other packaging applications,” said Mr. Rohrkemper. “With development and some imagination, there are applications for pretty much anyone with printing equipment.”
“The developing market for conductive inks constantly presents unique opportunities for Precisia’s products and services,” said Mr. Rohrkemper. “In addition to taking advantage of these opportunities, Precisia will continue to develop strategic alliances and partnerships with other businesses and organizations, whose products or services complement or enhance the company’s offerings.”
Precisia has a variety of silver and carbon water- and solvent-based conductive inks for screen and flexographic printing available.
Parelec’s Parmod VLT conductive ink formulations enable its customers to print electronic circuits on paper, polyester, polyamide and other substrates for a wide variety of electronics applications. Parmod VLT inks can be applied by screen printing and gravure and formulations are being developed for flexo and ink jet applications as well, according to the company.
The demand for conductive inks is still in its early stages and offers ink makers many opportunities to develop more advanced inks and formulations.
Mr. Ludmerer agreed that demand is set to increase for RFID technology and conductive inks. “Demand is growing rapidly, particularly in the burgeoning field of RFID. According to the Wall Street Journal, RFID is poised to replace barcodes and magnetic stripes and ‘will be in every product imaginable.’ RFID uses a radio signal that eliminates the ‘line of sight scanner’ used with barcodes or the ‘contact’ required with a magnetic strip.”
As more and more retailers begin to use RFID technology in their warehouses for inventory tracking, this market is poised to rapidly grow. “A research report released by Allied Business Intelligence (ABI) in June of this year estimates the global RFID market will grow to more than $3.1 billion by 2008,” said Mr. Rohrkemper. “Industry leaders have predicted that RFID technology has the potential to affect everyone in the coming years, either as a retail consumer or on another level. Wal-Mart, the world’s largest retailer, recently announced that it will require its 100 top suppliers to have all product pallets identified with RFID chips by 2005, and will require the rest of its suppliers to put RFID tags carrying electronic product codes on pallets and cases by the end of 2006. Publicly-defined, aggressive deadlines such as this one have added significant motivation to accelerate the creative and development process.”