In her opening remarks at the AUSA 2012 on October 23, 2012, Heidi Shyu, assistant secretary of the Army for acquisition, logistics and technology talked about a process she called strategic modernization planning, which “combines a detailed analysis of investments in S&T and material development linked to emerging threats and capability gaps across a long-term, 30-year time frame” in order to determine a roadmap to direct such investments. Items on the list include:
• reducing the load that soldiers have to carry by developing smaller, lighter energy sources;
• developing tactical situational awareness systems;
• networking and reducing the logistical burden of operating far from home bases. [1,2]
Several of these items have been on the Army’s radar for quite some time. Since the 1990s, the Defense Advanced Research Projects Agency (DARPA) and the U.S. Army have been on a mission to unburden soldiers of the enormous weights they carry by exploiting flexible display technology that will also provide more effective communication in the field. The Department of Defense (DoD) has developed requirements that include ultra-light weight, mechanical ruggedness, and high reliability.
The Flexible Display Center (FDC) at Arizona State University (ASU) has developed prototypes that meet these requirements and feature portable fullmotion, full-color displays that can be used to enable rugged, low-power soldier applications. The core technology can also be used to make lightweight ubiquitous sensors for force protection, or band-aid-like sensors that can monitor soldier performance or health in real-time, or assist in battlefield health management. Most recently, the FDC has responded to a need for a lightweight and tough X-ray imaging device that will be used to investigate suspected improvised explosive devices (IEDs). The current goal is to get these technologies out of the lab and into real-life flexible electronic devices for soldiers by transitioning them to volume manufacturing. This article discusses how to realize flexible electronics technology in a manufacturing environment by leveraging the existing infrastructure, which will reduce the need for major capital investment and thereby speed the transition.
The FDC Story
Early on, DoD efforts to replace rigid flat panel display technologies with unbreakable, flexible substrates stalled. The industry wasn’t interested in tackling the daunting technical challenges since flexible displays didn’t seem to be necessary in order to be highly successful in the consumer market.
To overcome this, the Army conceived of a public/private partnership that would attack some key technical challenges with the assistance of Army investment. A national competition was held among major research universities to identify a host. ASU was selected and the FDC was established, creating the first research and development facility in the world that is exclusively dedicated to working on flexible electronics. The FDC was formed through a cooperative agreement that allows ASU, the Army, and over twenty industrial partners to work together to achieve their common goal of accelerating the availability of flexible display technology for soldier applications.
The FDC’s centerpiece is a state-of-the- art pilot manufacturing facility located in the former Motorola Flat Panel business, which ASU purchased from Motorola in 2004 (Figure 1). Operated by a staff of professional engineers and technicians, the facility includes 17,500 square feet of class-10 cleanroom space that houses both a development-scale production line and a Generation II pilot display manufacturing line. Industrial partners comprise both system integrator companies such as Raytheon, Physical Optics Corp, Honeywell Electronics, and L3 Communications; and equipment and materials suppliers like EV Group, Dupont-Teijin Films, Henkel Electronic Materials, and Universal Display Corp.
Through active collaboration with member company teams, several prototypes of wrist-mounted infantry soldier information terminals incorporating electrophoretic ink (E Ink) displays were developed. More recently, this work has been expanded to include the development of full-color, full-motion video OLED displays that might, for example, be incorporated in the handheld terminals used by dismounted soldiers to control robotic assets. This technology has also turned out to be useful for lightweight and rugged sensing devices.
Together with a different collection of partners the FDC is developing a portable X-ray viewing device for investigating suspected IEDs in situ. Structurally, the digital film used in this device is similar to the thin film electronic control circuit in a flat panel display, which made rapid prototype development possible. Indeed, several other large area sensor arrays are envisioned as part of many future force protection systems.
The FDC infrastructure and partners provide an innovative means for rapidly developing a broad collection of flexible electronics beyond displays. Each new project enjoys an accelerated development trajectory because it can leverage maturing core technologies. What took years to develop for flexible displays can be adapted in a year or two to produce completely new prototypes.
Getting Ready for the Big Time
Now that the heavy lifting — putting thin-film transistor circuits onto something that isn’t glass — is done, the FDC is working to get the flagship product, a flexible display using E Ink technology, from the research environment into manufacturing (Figure 2). Concurrently, because the architecture of an X-ray sensing device is similar to that required for flexible displays, (Figure 3) these devices are being fast-tracked through prototyping and will be up next for technology transfer.
A full-color, full-motion video OLED version of the FDC’s flexible displays are also on the way, although their development will take longer because of two key engineering challenges. The first is the need to introduce new semiconductor materials into the thin-film transistor technology. The performance of the circuits that worked in E Ink displays is simply not good enough to drive OLEDs. The second, more difficult challenge is the need to provide a hermetic package for the OLED structure to prevent oxygen and moisture ingress that will destroy their function. While the technology to do this exists, the best way to translate it into an economic manufacturing process remains an unsolved problem.
Leveraging the Flat Panel Display Supply Chain
The next step to accelerating the availability of these technologies for soldier applications is establishing a reliable supply chain and then transferring the technology to a qualified manufacturer for wide distribution. Getting prototype systems in front of the acquisitions community can often be a critical step in motivating this transition. Fortunately, there is already clear interest in the kind of performance that flexible displays can provide. For example the program manager/ air warrior recently awarded a contract for a wrist-mounted soldier information terminal for helicopter pilots that will allow for in-the-field communications between soldiers. More recently, a program manager for the Defense Threat Reduction Agency requested the aforementioned X-ray sensors for identifying IEDs.
In the end it’s all about speed — how long does it take to get an application into the soldiers’ hands? Whenever possible, it’s important to rely on and leverage the existing infrastructure. In the case of flexible displays the biggest problem was figuring out how to take a thin and flexible substrate and process it in equipment used to manufacture a rigid piece of glass. At the FDC this has been solved by temporarily bonding Dupont-Teijin Film’s high temperature Teonex film to a carrier panel. After fabricating thin film electronics on it, a debond release step is performed. Other than that key innovation, the production of thin film electronics is the same as that already used in flat panel display manufacturing. It uses the same deposition, photolithographic patterning and peripheral electronics integration processes. The new bond/ debond process requires additional tools, but the rest of the existing infrastructure can be used as is.
To achieve all of this, the FDC has relied heavily on its industrial partnerships. For example, EV Group has developed several novel coating tools used in the FDC process line. DuPont- Teijin Films developed the thin film plastic, and Henkel engineered an unusual new adhesive that made the new bond/debond process possible. For its part, Honeywell Electronic Materials created a new dielectric material that improved the performance of flexible, thin-film electronics. Work with the system integrators Raytheon and Physical Optics, among others, has helped the FDC develop demonstration systems incorporating the flexible displays.
Finally, while the FDC’s facility in Arizona is suited to low-volume manufacturing of these devices, volume manufacturing will require transfer of the process to a large-scale manufacturing partner. ASU is already engaged in licensing discussions or negotiations with several domestic and foreign manufacturing partners.
Partnership is Power
Ideally, the path to manufacturing begins when prototypes are made available to system integrator partners to enable concept demonstrations for the Army acquisition and user communities. These help them to visualize the way that these new technologies can help to address the challenges that they face in the field.
In this way, several key flexible electronic systems have been successfully demonstrated, and thanks to the interest of the Army’s soldiers, they could be well on their way from the lab to the front lines. By working closely with its partners, the FDC has managed to find a way to use much of the manufacturing infrastructure that is already in place. Now it’s a matter of getting a crucial first product identified to complete the transition of this exciting new technology. This will create a clear path for future flexible electronics technologies that promise to enhance soldier capabilities and lower their weight burden.
This article was written by Nicholas Colaneri, Director, Flexible Display Center, Arizona State University (Tempe, AZ). For more information, Click Here