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The Starry Skies concept

The Starry Skies concept, an advanced lighting and projection system, enhances the flying experience.
Image: Boeing

Boeing is using flexible hybrid and additive electronics to develop new ways to produce intricate components that provide big advantages in many areas.

By John D. Williams, Associate Technical Fellow, and Robert Smith, Technical Fellow, Boeing Research & Technology

Over the past two decades, electronics systems have become ubiquitous in people’s lives thanks to the increasing availability — and the continual reduction in size and cost — of open source electronic components.

The iPhone combined internal acoustic, vibration, temperature and GPS sensing into a single commercial product for open source programing in 2007. However, these sensors were dedicated to the prescribed functionality of the phone.

Then a relatively quiet shift came in the everyday use of low-cost, microcontroller-driven transducers, initiated by the release of the Arduino in 2008. Makerbot followed in 2011, promising the ability to 3D print — in your garage — any plastic structure desired.

Next came Raspberry Pi in 2012, which gave teenagers a $50 computer to program and code. By 2015 nearly every engineer — and most American high school students — interested in sensing applications, robotics or technology development had daily access to every one of these products.

Despite this advance, these devices are still clumsy. Adapting them to a specific and reliable sensing application is not trivial and requires multiple connectors between rigid circuit boards through wires, cables and wireless networks.

Today, the maturation and combination of silver ink processes, with laser machining, and 3D printing is poised to provide the next revolution in ubiquitous low-cost sensing platforms. Boeing is using flexible hybrid and additive electronics to develop new ways to produce antennas, sensors and multilayer circuit boards that maintain performance while providing advantages in component cost and weight with dramatic savings potential for integration and test.

By 2022, many maker-space products will use tools that combine additive manufacturing with computer numerical control milling, laser drilling and printed electronics to enable electronics and sensing architectures on or in flexible and 3D-printed structures.

Both flexible hybrid and additive electronics require precision patterning of multiple electronic materials with critical dimensions of 1 mil or less on both planar and curved surfaces. The limiting factor for realizing this vision is sufficient process control when printing multilayer electronics and the die attachment of integrated circuits to eliminate conventional connectors, cabling and bulky sensor packages required today.

Many of these applications benefit from small low-cost sensor arrays and wireless networks that are becoming a tool for monitoring, manufacturing and operation of mechanical and aerospace systems. These systems become new data collection devices to enable big data analytical capabilities.

This technology has been under development at Boeing for more than five years. Important examples include the printed Starry Skies concept for cabin lighting in airplanes and conformal patch antennas for Boeing Defense, Space & Security.

In 2016, Boeing joined the NextFlex Consortium, a manufacturing innovation institute established by the U.S. Department of Defense, to support industrywide improvements in the manufacturing readiness level (MRL) of these technologies. Through NextFlex, Boeing has provided industrial leadership in materials testing, multilayer fabrication, radio frequency applications and industrial health monitoring device architectures.

The results to date provide a general-purpose MRL 5 or higher for flexible hybrid electronics technologies. Within the next two years, our team will widen these efforts to include unmanned autonomous vehicle flight, composite health monitoring, multilayer flexible PCBs and dozens of sensing applications across the company.

This will be achieved through extensive use of thinned microcontroller integrated circuits mounted directly to the flex board. Coupling these achievements with materials characterization, in situ process monitoring and large-area digital printing will provide Boeing with an MRL 7 small-scale production capability for the next generation of electronic sensing. By 2022, Boeing will have the manufacturing readiness required to implement flexible hybrid electronic devices in both stand-alone and 3D-printed industrial products.

    Figure 1

    Figure 1

    The first printed sensor system with on-board power and wireless interface is now in development. The condition monitoring sensor array prototype, shown here, combines a microcontroller, battery, Bluetooth data link and four sensors onto a single flex circuit. The Boeing team is working to combine these technologies into a 2x3-inch footprint and test them in a factory environment. This development effort has led to a number of small sensor maturation efforts for Boeing Commercial Airplanes, in which the team has programmed and tested sensors for UV monitoring and wing gap detection on the 777X product line.
    Photo: Boeing

    Figure 2

    Figure 2

    Boeing has developed unique patented flexible antenna arrays. The antenna design shown here has been manufactured for a wide range of applications between 900 MHz and 85 GHz. The design provides a 10% bandwidth at the center frequency and are roughly one-tenth the thickness expected from a conformal patch array. The team has also shown how the performance of these antennas varies as a function of the shape they are mounted on. This flexible antenna array technology is now being tested for communication links throughout Boeing, including electromagnetic monitoring of the 787 factory floor in North Charleston, South Carolina.
    Photo: Boeing