Conductive inks and pastes are essential elements for flexible and printed electronics, and leading suppliers say they are seeing interest in innovations that will enhance end-use products.
John Hannafin, global product manager, Sun Chemical, said that printed electronics manufacturers must be convinced that any innovation will enhance the device, be competitive, and have a reliable global supply infrastructure.
“We are seeing more inquiries for smart packaging, especially with regard to certain innovations which demonstrate that the consumer brands need some form of interaction,” added Hannafin. “Newer innovations, including smart surfaces, are hoping to create intimacy and engagement at the consumer level to improve the buying experience. Nanomaterials such as nanosilver could enable significant advancements in a broad range of applications, including photovoltaic and semiconductor packaging. Other innovations are on the drawing the board. It is clear that this space will drive more and more personal connections.”
Chris Booher, chief marketing officer for ChemCubed, said that most of ChemCubed’s opportunities stem from the critical applications that require either conductive performance efficiency or printing process efficiency of the materials.
“ChemCubed’s ElectroJet brand silver conductive inks are particle-free materials that achieve near bulk conductivity performance,” Booher noted. “It may be printed through a variety of deposition technologies, including inkjet and aerosol jet, depending on the feature resolution required for the application. The ElectroJet silver conductive ink also fully sinters (cures) as low as 80°C in a matter of minutes, enabling the sintering process to be done in-line during the printing process (via heated platen). Other versions of silver conductive inks (paste/flake, nano-particle, etc.) cannot achieve the conductive performance for critical applications and may require sintering at a min of 130°C for 30 minutes. Many applications are temperature sensitive, in which case, the low temp sintering feature is a required feature.”
Kerry Adams, market segment manager, DuPont Advanced Materials, said that he now sees customers demanding complete solutions rather than just “oh here you go – here is a really conductive silver ink.”
“They need systems of materials and substrates that work seamlessly together and are reliable,” added Adams. “They need design advice. They need help with prototyping and parts. The technology is demanding and customers need confidence that a materials sup-plier can supply all these things along with the capability of large scale consistent manufacturing.”
C3Nano CTO Dr. Ajay Virkar observed that typically when a new technology is to replace the old, the performance bar is set by the incumbent.
“For transparent conductive inks and films, the first challenges were to match the optoelectronic properties and more importantly the reliability of the rigid solution (like ITO),” said Dr. Virkar noted. “Of course, there are new requirements like flexibility specifications that are somewhat problematic for some competing technologies. However, our Activegrid product is very flexible and has met the most stringent flexing requirements. We are now developing different inks for various coating methods and directly printable inks. We are also working on stretchable conductors and materials.”
Stephan Gachet, VP sales for Genes Ink, reported that traditional silver polymer pastes are showing their limits with the development of electronic new applications such as IME, security and shielding.
“Electronic designers need more flexibility, more conductivity, using less material, with thinner prints, enabling more complex, multilayer printed electronic circuits that are not obtainable with current materials. It also helps in cost reduction versus actual processes,” said Gachet.
Ken Klapproth, VP of marketing for CHASM Advanced Materials, Inc., said that the two properties that customers are trying to balance across a variety of applications are “transparency” and “conductivity,” adding that the material needs to be transparent enough to appear invisible but also need to be conductive enough to provide a reliable circuit.
“For example, a heater will need to carry more current to provide heat than a smartphone touch screen which works off the capacitance of your finger,” Klapproth added. “Since the heater is not typically in front of a high-resolution display, it does not require the same level of transparency as the smartphone. Our materials provide a range of transparency and conductivity to suit many applications from 1 ohm/square conductivity needed for transparent antennas at 90% VLT transparency to 75 ohms/square conductivity needed for touch screens and sensors at 99% VLT transparency. We like to say that our transparent CNT Hybrid materials enable innovative engineers in any industry to create the best flexible printed electronics they’ll never see.”