Large format touch sensor capability with 2.5 and 3D formability

Large format touch sensor… With large format interactive displays becoming more ubiquitous - from large indoor and outdoor displays to electronic whiteboards - the need has increased for advanced materials that are highly sensitive, quick to respond to touch, and capable of achieving a variety of complex forms and shapes.

At the Consumer Electronics Show, January 6-9, 2016 in Las Vegas, SABIC will introduce a transparent, conductive polycarbonate (PC) film that represents a completely new class of display materials with outstanding transmittance and resistance, especially in large formats, with exceptional 2.5 and 3D formability. In addition to its potential performance capabilities in large format displays, this solution also stands apart in its ability to be thermoformed into complex 2.5 or 3D shapes, such as those required for a variety of displays in consumer electronics, automotive interiors and healthcare devices, as well as for architectural uses. The film combines Sante nanoparticle technology from Cima NanoTech over a substrate of SABIC's renowned Lexan film to achieve highly sensitive touch screens that are also impact resistant and formable.

"With the need for information to be constantly at our fingertips, the challenge becomes how to integrate touch screen functionality into spaces where design and aesthetics are also important - such as in an automotive interior or wearable technology - or where extremely large format touch screens are required, such as digital signage or electronic white boards. Other challenges include transparency and, of course, cost containment wherever possible," Alan Tsai, Director, Technology & Innovation for Display & Electronics, noted.

There are alternatives on the market today, such as indium tin oxide (ITO)-based solutions over a glass substrate and conductive polyethylene terephthalate (PET). SABIC's solution has definite advantages over both, according to Tsai. "First, our transparent, conductive polycarbonate solution is more sensitive, which can bring the response times of small size touchscreens to large format touchscreens. The material is capable of 20 ohm/m2 (compared to ITO, which is > 100 ohm/m2) and in fact, SABIC has created a 55'' demonstration touchscreen display that delivers real time response."

And, when compared to ITO laminates over a glass substrate, Tsai offers that SABIC's transparent, conductive polycarbonate film - available in gauges from 800 micrometers to 125 micrometers - provides considerable weight savings, which can support thin wall designs as well as potentially reduce transportation costs. Another key advantage is formability: the use of ITO is challenging when considered for flexible touch screens due to its brittle nature. When flexed, ITO will crack, thus preventing the operation of the touchscreen.

PET-based solutions are also often considered. However, when compared to SABIC's Lexan film solution, its resistance is relatively high (>150 Ω/m2) and the material exhibits lower conductivity. PET lacks the rigidity and impact resistance properties of polycarbonate, creating challenges when attempting to achieve large format displays. It, too, exhibits only average formability because PET is not capable of withstanding the higher temperatures needed to thermoform the material into complex designs, a definite advantage of polycarbonate.

A case in point is center display stack (CSD) for automotive interiors, which typically includes touchscreens for navigation, infotainment features and back-up cameras as well as an area for climate control. With advanced materials such as transparent, conductive polycarbonate film, the opportunity exists to create an integrated CSD design to consolidate these controls in one unit. Conductive PC film can achieve the forms and curvatures typical for center display units with multiple touch-enabled sensors for navigation and infotainment without compromising the self-capacitive capability for climate controls.

SABIC has made available large scale samples of its transparent conductive PC film in either sheet or roll form with web width up to 1.2 meters for use in customer trials, with commercial scale quantities available in the second half of this year.

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