Future Advances in Electronic Materials and Processes - Flexible Hybrid Electronics

February 1, 2020

Air Force Research Laboratories, Wright-Patterson Air Force Base, Ohio

This project performed an integrated assessment focused on projected advances in electronics materials and processes over the next 25 years and their implications for military aerospace applications, with a particular emphasis on flexible hybrid electronics (FHE).

In essence, FHE is a combination of conventional inorganic semiconductor circuits and microelectronics fabrication processes and packaging with rigid or flexible, organic or inorganic electronic components and techniques for digital functional printing on rigid or flexible-substrates. One key concern for the U.S. electronics industry, and for defense electronics in particular, is that while significant research and development in electronics occurs domestically, much of the manufacturing strength for electronics products resides overseas. The emerging FHE field is no exception. This tendency for stronger foreign manufacturing of electronics implies that U.S. defense organizations must actively work to ensure the availability of domestic suppliers and improve their capability to meet the demand for increasingly sophisticated defense electronics.

The performance of electronic systems, both military and civilian, has indisputably grown at an impressive rate since the birth of the electronics field. This is due in great part to continued improvements in the miniaturization of electronic components and systems, and the resulting reduction in the size, weight, and power (SWaP) required to implement functions of increasing complexity, in addition to progress in inorganic semiconductor materials that can outperform silicon in speed and power. However, miniaturization and advances in inorganic materials are not expected, at least not by themselves, to enable the next revolution in electronic systems and applications.

The next wave of revolutionary progress in electronics will greatly rely on easily customizable electronic devices and systems that can be quickly and affordably manufactured and integrated, possibly conformably, using a variety of deposited materials on a variety of multifunctional substrates. Mechanical flexibility will be a desired characteristic for many applications, but flexibility in manufacturing is vital for this new wave of electronics. Recent progress seems to indicate that the desired flexibility in manufacturing of electronics systems is indeed attainable. For example, the development of inks, printing processes, and roll-to-roll capabilities for manufacturing of electronics is already a reality. A variety of electronic packaging designs have also been researched and developed that combine high-performance rigid and/or flexible inorganic electronics devices with organic materials on flexible substrates.

However, significant development is still necessary before the performance and reliability of FHE products can approach those of systems produced using conventional electronics manufacturing. For instance, in spite of significant progress in materials and processes, organic semiconductors are not yet capable of the high charge carrier mobility and high power capacity required for uses beyond the pervasively proposed but not yet widely successful conformal, printed large-area display, photovoltaic, and sensors applications.

Even after achieving the performance and reliability characteristics demanded by initial applications, FHE systems for military use will have to satisfy more stringent requirements than those expected for consumer applications. For example, appropriately designed and applied coatings can help protect the integrity of FHE systems in severe environmental conditions of temperature and humidity. Military applications also make it necessary to account for vibration, shock, and similar environmental challenges. In addition, common flexible substrate materials are not compatible with fabrication processes that require elevated temperatures, and therefore development of more resilient substrate materials is required.

In spite of current shortcomings, FHE as an emerging industry has grown steadily and its application domains are expanding. Forecasts for the growth of the flexible (printed and hybrid) electronics market are abundant and vary widely, and each of them focuses on particular needs, technologies, and agendas. Regardless of the differences in these predictions, it is clear that printed electronics, flexible electronics, and their combinations are expected to expand rapidly. Moreover, the adaptation of conventional (e.g., CMOS) electronic technologies to flexible substrates and packaging will enable FHE use in applications beyond those possible with conventional electronics.

This work was done by Enrique A. Medina, Kaitlin Schneider, Robert Denison, Jill Csavina-Raison, Douglas Hutchens, Robert Drerup, and Roberto Acosta of Universal Technology Corporation; Jud Ready, Suresh Sitaraman, Stephen Turano, Cheong-Wo (Hunter) Chan, Xiaojuan (Judy) Song, Matthew King, and Brian Faust of Georgia Tech Applied Research Corporation; Savas Kaya of Ohio University; and Arthur Temmesfeld of Temmesfeld Associates for the Air Force Research Laboratory. AFRL-0281

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This Brief includes a Technical Support Package (TSP).

Future Advances in Electronic Material and Processes: Flexible Hybrid Electronics

(reference AFRL-0281) is currently available for download from the TSP library.

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