Printed Electronics for Aerospace
December 1,2011, Printed Electronics USA 2011, Santa Clara, CA—Jeff Duce from Boeing identified the needs and requirements for aero-quality printed electronics. The drivers for this interest are lighter weight, lower complexity, added capabilities, and higher reliability leading to lower maintenance requirements.
Printed electronics are an enabler for constant improvements in planes. Examples of printed electronics applications include a damage detection sensor for 747-8 series. These sensors measure structural integrity in the airframe. Another set of sensors measures forces and angles of the actuators in the wing flaps.
These and many other printed electronics subsystems need to pass some very stringent test. The fatigue test puts a component through a range of 0-5,500 microstrain compression bends. So far, printed traces have 0 failures and a 3 percent resistance increase over 6 million cycles. In comparison, photo etched traces had a 30 percent failure rate and a 104 percent increase in resistance after 240k cycles.
For the thermal test, parts are run through a -65° F to 160° F range for 2,000 cycles. Printed traces exhibited a 5 percent increase in resistance while photo etched flex circuits increased resistance of 270 percent. Here, we can see that only the printed electronics meet the structural and environmental requirements for an airplane.
The circuit boards and components are not the only area of concern. The wiring harnesses are heavy, complex, and expensive. In addition to the structural and environmental requirements, the cables are also subject to abrasion and punctures. Printed electronics can reduce a lot of the wiring in entertainment displays, integrated wiring, sensors, antennas, structural health monitoring, and in part identification and authentication.
The biggest issues for printed electronics are the environmental ones. All electronics must be repairable and immune to fluid susceptibility. They must have good temperature stability and structural durability and must survive lightning strikes and EMI events. In addition, all of the components are expected to survive over 20 years in operation in these harsh environments. The quality requirements for aerospace require certifications, and this requirement applies to the sub-tier suppliers for materials like ink and substrates.
The technologies needed for aerospace from the printed electronics industry include corrosion resistant, high conductivity materials. These materials have to scale up to in-place sizes of a airplane fuselage. Among the needed materials are interconnects and substrates that can help to reduce weight, replace existing systems in a smaller volume, and add new capabilities without impacting existing power and weight budgets.
