By Mike Forde and John Dobroski
With the ever-increasing pace of commercial electronics and computer technology, it has become mandatory to base military electronics products on cost-sensitive commercial off-the-shelf (COTS) components. Gone are the days of specifically designing all components to strict military specifications. The new era of military electronics requires a focus on low cost, value, and proper integration of COTS components in product designs. This mandates military COTS suppliers to push components beyond manufacturer's specifications by properly packaging and integrating these components into their products. The military electronics provider of the new millennium must know how to yield rugged, militarized products using standard components and must be ready to incorporate new technology as the commercial world advances.
Designers at BARCO Display Systems in Duluth, Ga., have produced rugged electronics products for military applications for more than 15 years. During this time we have learned many valuable lessons regarding COTS component integration and have patented electrical and mechanical designs that achieve the desired specifications for equipment placed into military environments. While today's military procurements do not always specify MIL-STD testing of final products, we at BARCO continue to test our equipment to military specifications since they provide the only practical standard by which to measure and compare competing products claiming to meet the tough environments that our military customers demand. It is our responsibility to review, select, and package COTS components to enable the final product to survive in the required application. This is the value added we provide to our customers.
The military COTS supplier must take into account that the original COTS component manufacturers did not originally intend many of these components for the military market. COTS components are designed, targeted, and intended for commercial markets and there is little or no motivation to specify these products for use outside commercial applications. Testing is expensive and unnecessary, and wider specifications would only unnecessarily increase their product liability.
This fact, however, does not in any way imply that these COTS components will not operate well outside of these commercial specifications and, in many cases, across the entire range of required military environments. This fundamental design philosophy requires the military COTS supplier to first become an expert in the commercial component technology to lower product development risk.
During the development of our large-screen liquid crystal display (LCD) products, BARCO experts evaluated commercial LCD panels from a variety of panel manufacturers. We found all commercial panel manufacturers defined a storage temperature specification in the range of -20 to 60 degrees Celsius. These LCD panels were also designed for the commercial marketplace and not intended for life-critical applications such as aerospace, submarine, military, and medical use.
While this appeared to present a roadblock to integrating current-technology LCD panels for the military, it merely required BARCO to perform a more stringent, detailed level of component integration and testing. Knowing this, BARCO engineers evaluated the detailed structure of the standard commercial product and created a design to enable this commercial product to survive harsh military environments.
After examining each commercial LCD panel, we determined that the interconnections of the row and column drivers (TAB's) with the LCD glass were potential mechanical failure points in temperature extremes. We also learned that basic LCD technology requires additional packaging and integration design to strengthen the LCD glass, thermally warm the panel at extremely low temperatures, and shield the panel from electromagnetic interference. BARCO determined that removing the panel from the commercial packaging and building a proprietary rugged front end and mechanical frame was the only way to assure a compliant display product using any COTS LCD component. This kind of packaging protects the commercial-grade display from shock, vibration, and thermal expansion.
BARCO engineers mechanically strengthen the panel in two ways. First, they bond a piece of glass to the LCD, and then they mount the TABs on this same glass surface to strengthen the interconnection between the LCD and TABs. We also add special coatings to provide even heating over the entire LCD surface to enable a rapid warm up during cold-start situations and shield against electromagnetic interference. This bonded glass keeps the LCD within a fixed frame to reduce torsional and thermal expansion effects.
One example of our COTS LCD ruggedization is the BARCO RFD251 20.1-inch LCD, which incorporates the NEC 20.1-inch commercial LCD panel in the BARCO-proprietary front end. Barco experts qualified this display in accordance with MIL-STD-810E for environmental requirements. BARCO performed and the RFD251 passed the 48-hour non-operational cold-storage test at -40 C (per Mil Std 810E, Method 502.3, Procedure 1).
To assure long-term survivability of the NEC 20.1-inch panel during cold-temperature storage, BARCO cold soaked a production RFD251 display at -50 C for 90 hours. BARCO verified that the rugged RFD251 display successfully survives this extreme test duration with no problems.
BARCO performs additional testing to evaluate how each product will respond over its lifetime, commonly referred to as Highly Accelerated Life Testing, or HALT. During HALT, test experts subject the ruggedized product to continuous temperature cycling over an extended period of time. BARCO exercises temperature extremes from -20 C to 70 C for our products. Moreover, in the case of the RFD251 we have performed more than 12,000 hours of this testing with no failures of the LCD. The ruggedization and testing process is expensive, yet produces quality rugged products for extreme environments.
As a side benefit of the RFD251 LCD integration, BARCO developed a low-profile mechanical envelope that sits flush in a 19-inch rack. The COTS component standard packaging often may present a fundamental mechanical fit problem that requires the military COTS supplier to become expert in each technology or else create elaborate workaround solutions.
At BARCO, experts review designs for "technical sustainability," or the ability to sustain the design into the future. We must be able to advance alongside component technology to keep the military electronics up to date. Basing the design on commercial form factors enables our designers to incorporate future advancements throughout the production lifecycle and allows existing units always to have current technology. Acknowledging and planning for change assures long-term product availability with complete technology-insertion capability.
Properly evaluating and integrating the COTS components avoids the need to constantly re-design products or to continually search for alternatives in the hope of finding a combination that happens to work. We still must provide products that are ready for their real-life environment that will not fail when deployed.
Mike Forde is the Product Group Manager of Rugged Displays for BARCO nv Display Systems in Belgium. He has designed and managed projects such as radar countermeasure and display systems for more than 18 years. He has a BSEE in from Washington State University and an MBA from George Washington University.
John Dobroski is Manager of Display Products, North America for the BARCO Inc. Display Systems division in Duluth, Ga. He has been an engineer and product/program manager in the avionics display industry for more than 13 years. He was program manager for several U.S. defense programs at Rockwell Collins in Cedar Rapids, Iowa. He also holds a BS degree in electrical engineering and an MS degree in computer science from the University of Iowa.