As many electronic devices use less metal in their enclosures in order to reduce costs, the requirements for EMC increase since a potential Faraday cage—a conductive enclosure completely surrounding the shielded object—is lost.
Electromagnetic interference (EMI) is highly regulated by government agencies throughout the world. Thus aside from the actual performance of the devices and their impact on, and from, other devices, additional EMC requirements may be present because of the regulations. While the goals are similar in the various geographies around the globe, there are differences that can impact the EMC approaches used in manufacturing for different target geographies.
As a result, materials firms have long been on the lookout for new materials that can generate profits for them in the EMC sector. Materials that have been tested or used in this sector include conductive polymers, TCOs and carbon materials.
Carbon nanotubes can be used for EMC applications in small quantities and are not inherently expensive. Their current high cost is due to their newness. Carbon nanotubes, or some of them anyway, are more conductive than any metal and are easily made into diffusely dispersed suspensions. Carbon nanotube coatings or filled polymers can offer an interpenetrating conductive network that produces a Faraday cage with minimal quantities of material.
Conductive polymers like PEDOT:PSS have proved suitable for some EMC applications. However, they have not come down in price as rapidly as hoped. Still, they are flexible and often transparent, especially in thin layers, and offer the likelihood of low cost within the next several years. All of these features are attractive in certain EMC applications.
Other nanomaterials used for EMC coatings include metals, mostly silver. The small size of nanoparticles offers the potential to use such small amounts of metals that even an expensive metal like silver is not cost prohibitive.
By creating a feeling that is as close as possible to paper, industry is aiming to replace paper with electronic paper. The present electronic paper uses glass substrates, but by replacing them with plastic substrates, while maintaining visibility, memory and energy-saving characteristics, it can be made flexible. By changing the material from glass to plastic, the following merits can be obtained:
• Safety. There is no need to worry about cracking or breaking.
• Weight reduction. In comparison with the same size glass panel, the weight reduction ratio will be one-tenth (in-house comparison).
• Thinness. In comparison with the same size glass panel, the thinness ratio will be one-fifth (in-house comparison).
By making it flexible, electronic paper excels in portability, and it is anticipated that it will become the perfect new device for the mobile society of the future. In addition, installation on curved surfaces, which used to be impossible has become possible, so the potential uses of the displays will be broadened.
As depicted in the road map graphic on the previous page, monochrome flexible displays will be in production this year and color flexible displays will be sampled this year and in production next year in 2011.
This year and next will see logistics/physical distribution and electronic information media input stylus applications on glass substrates while in 2011, Bridgestone projects electronic information media input stylus and IC cards over flexible substrates.
The new business opportunities that are being shaped in displays, signage and printable electronics include exciting new segments—lighting, photovoltaics, RFID, sensors and batteries—all requiring technical challenges in coating and ink technologies.
These newer materials are among the most exciting developments in a field that has been otherwise fairly mature for many years.