Developing Foldable Displays and Touchscreens
New technologies will help make flexible, three-dimensional or foldable displays an essential part of our everyday lives.
Read the latest news while relaxing at home, in a café, at the beach, in the mountains or in a self-driving car on a highly flexible, rollable, and foldable touchscreen. This may sound like a pipe dream, but it could be a reality in the next five years. In fact, these flexible, three-dimensional or foldable displays could evolve to become an essential part of our everyday lives.
Electronic materials play a key role in this form of printed electronics. Through innovative material and system solutions, Heraeus and the Industrial Technology Research Institute (ITRI) in Taiwan are accelerating the development of flexible touchscreens. Current materials are not suitable for this application because they are not mechanically flexible enough. One solution for this interface comes in the form of Clevios™, a conductive polymer that can be used in touch panels. At the recent LOPEC trade fair for printed electronics, Heraeus presented an improvement in touchscreen production: a flexible, fully functional 7-in. (17.8-cm) touch panel on a polyimide film substrate (12 micrometers thick) that serves as a curved sensor that controls an LCD display.
“Our prototype is a fully functional, flexible touch panel that can be produced on an industrial scale,” said Armin Sautter, Ph.D., director of Technical Service Displays at Heraeus New Businesses. “In comprehensive testing, the multi-touchscreen withstood 10,000 bending cycles at a 5 and 3 mm bending radius without any issues.”
Heraeus developed the improvement for mass production of Clevios-coated films in a collaborative research project with ITRI. With this conductive coating, manufacturers can produce touchscreens with improved functionality on an industrial scale—for flexible, curved, 3-D touchscreens, as well as other applications such as wearable functional apparel. The 7-in. touch panels can also carry out multi-touch functions with five contact points.
A large portfolio of materials and technologies is available for printed electronics, including conductive polymers and printing pastes, as well as process technologies such as specialty light sources. In addition to using suitable materials for printed electronics in displays produced by the meter, fast drying surfaces and good conductivity of the applied silver pastes are also important. A newly developed infrared module achieves this in a fraction of a second (0.32), making it almost 2,000 times faster than traditional drying processes with conventional heating plates or hot air.*
Metallic nanoparticles for printed electronics are frequently applied to flexible, temperature-sensitive polymer materials in an inkjet printing process, then dried and sintered. However, a roll-to-roll process is necessary for mass production. The optimal process should dry and sinter quickly and efficiently while not damaging the often temperature-sensitive polymer substrates. A custom infrared module for this purpose has been developed that requires 0.32 seconds for drying and sintering.* By contrast, this process takes around 10 min with a heating plate. Due to the custom infrared system, the printed electronics on the film roll can be dried and sintered quickly in a single step.
*Developed by Heraeus.
Consumer Electronics Drive Development
The LOPEC trade fair showcased the lightning-fast development in printing processes and materials for the electronics industry, and highlighted the potential of printed electronics, which are already found in countless everyday items like displays or printed antennas. “The main driver of consumer electronics is ongoing customer demand for improved devices with higher performance,” said Sautter. “From a customer perspective, foldable and rollable displays are extremely important, because customers want larger and larger screens, but at the same time, they want a compact, transportable device. That’s actually a contradiction, but one that can be solved in the future with flexible, foldable displays that can be folded and rolled like a newspaper.”