Electronics experts developing technology for aerospace and defense applications confront few issues as daunting as the heat generated from their designs. Engineers are under constant pressure to develop ever-smaller and more powerful electronics, yet the cost of doing so creates ever-larger amounts of heat, and ever-larger electronics thermal management problems.
Among their core challenges, then, is how to remove all this heat, while preserving system power and performance, as well as reducing size and weight for military and aerospace applications like unmanned vehicles, night-vision equipment, and body-worn computers, sensors, and signal processing.
Electronics heat removal and thermal management is pressing for the development of new materials to wick heat away from components on boards and in chassis, and also is providing incentive for systems designers to rethink their commitment to commercial off-the-shelf (COTS) technology.
"In the military we still believe these systems have to be out there for 50 years, but how can you design these systems for upgrading over that time," says Gerald Janicki, senior director for programs and business development at Meggitt Defense systems Inc. in Irvine, Calif. "The easiest way is to pull away from COTS," Janicki says.
Instead, Janicki suggests that one approach to removing heat efficiently from military and aerospace electronics systems is to design them from the beginning with heat removal in mind, rather than what has been the engineer's traditional approach over the last two decades of designing with COTS technology and cooling as best he can.
Pressing needs for new ways to cool electronics also are encouraging systems designers to try different kinds of materials to conduct heat away from critical components. Materials approaches for conducting heat off of chips and boards often are closely held company secrets. "The higher the thermal conductivity, the better. This is a competitive advantage," explains Ivan Straznicky, principal engineer and technical fellow at Curtiss-Wright Controls Embedded Computing in Leesburg, Va.
Straznicky says there is at least one unintended benefit of ever-growing needs for system performance and power to the thermal-management engineer. Demands for more power are leading computer experts to use new generations of multicore microprocessors, and these devices tend to be physically larger than their single-core predecessors.
Larger devices are easier to cool, he says. "The latest and greatest Intel processors, like the Core i7, are around 45 Watts, which is a big jump from previous processors. The silver ling is because they are adding more cores, the die size is getting bigger. It's not just the amount of power you have to cool, but the amount of power per square inch -- or the power density," Straznicky explains.
For these devices and other heat-producing components, embedded computer designers using conduction cooling not only are looking into new heat-conduction materials that are able to able to withstand shock, vibration, and other extreme conditions of aerospace and defense applications, but they also are investigating more exotic approaches, such as heat pipes and vapor chambers, Straznicky says.
Designers using convection cooling are considering new developments in large heat sinks, stepped-up air flow with fans or blowers that act like turbines inside electronics enclosures that enable systems designers to increase air flow over hot components.
Where the latest conduction- or convection-cooling techniques fall short, however, designers are looking into the kinds of liquid-cooling approaches that call for the kinds of point designs that eliminate COTS parts. These approaches are expensive, and designers use them only where other techniques cannot do the job, Janicki says.
"The better the industry gets at packaging, the better they are at thermal management, "Janicki says. "We have a lot of challenges ahead of us."
One application that may drive the newest electronics cooling techniques is the U.S. Army's Ground Combat Vehicle (GCV), which essentially will be a much larger version of the Bradley Fighting Vehicle," Janicki explains. "GCV has a lot more electronics, more communications, and more defensive systems on it," he says. " These things will all require cooling; some things will be air cooled, but some things will need to be liquid cooled or cold-plate cooled."
Electronics thermal management company information
MH&W International Corp. Thermal Products Division; Mahwah, N.J.; 201-891-8800; www.mhw-thermal.com
Join the PennWell Aerospace and Defense Media Group on Linkedin at http://bit.ly/9MXl9
Become a fan of Military & Aerospace Electronics on Facebook at http://bit.ly/1VGM0Q
Join your industry colleagues in the Command Post community online at http://community.milaero.com