In school, we knew we were doing OK when we passed the teacher’s test. But the stakes are higher now than in school days of yore: Testing commercial x86 designs and electronics adapted for use in rugged battlefield environments anywhere in the world is a matter of life and death (Figure 1). Same goes for the transportation industry. And, as discussed in Part 1 of this series, “Adapting commercial x86 embedded designs to harsh environments – Not as straightforward as you think,” prepping ruggedized commercial wares is not a matter of merely tacking on additional bolts or boards. So … what precisely is involved in this life-, mission-, and safety-critical testing? And must it be done on every single product that comes down the pipe, or does sample testing cover all the bases?
[Figure 1 | Commercial-turned-rugged x86 designs and electronics can be found in rugged battlefield environments anywhere in the world. Testing is imperative to their reliability – and a matter of life and death. Pictured: An A-10 Thunderbolt II, presently engaged in combat missions over Afghanistan supporting Operation Enduring Freedom. U.S. Air Force photo by Master Sgt. Robert Wieland]
Show me the rugged … but when?
When ruggedizing a commercial x86 system, parts qualification is mandatory, and there are various schools of thought. Perhaps the most compelling, however, is the choice between: Should a company qualify the parts by test or guarantee them by design?
Qualifying by test happens when upscreening occurs exclusively at a subsystem, board, or other high levels of integration, while the board or subsystem’s individual off-the-shelf components remain untested for harsh environments. This practice can sometimes even pass some levels of Highly Accelerated Stress Screening (HASS), but the result will always be early and unpredictable failure for the module.
On the other hand, guaranteed by design comprises 100\% inspection and rating of individual mechanical devices and components – before they are integrated into a board or system. This is vital when “failure is not an option.”
Case study: Do we have to do this every time?
Christine Van De Graaf, Kontron’s Product Manager, Embedded Modules, utters a resounding “yes” when asked if it’s really necessary to test each individual commercial-turned-rugged component. Terminology aside, Kontron, a Premier member of the Intel® Embedded Alliance, subscribes to the aforementioned “guaranteed by design” philosophy in cases when commercial-grade components must be used. Most of Kontron’s military and transportation customers request the industrial temp range of -40 °C to +85 °C, she says – a range beyond the grasp of commercial-grade embedded products (Figure 2).
[Figure 2 | Most of Kontron’s military and transportation customers request the industrial temp range of -40 °C to +85 °C, which is beyond the grasp of commercial-grade embedded products.]
But the converted commercial wares are in for anything but an easy ride. Kontron’s screening includes strenuous thermal testing while cycling the Unit Under Test’s (UUT’s) temperature, running burn-in tests, soaking the device, and conducting several other (albeit proprietary) test procedures.
Testing is additionally performed for moisture and corrosion resistance, and Kontron uses Humiseal 1B31, inspection-friendly via its black-light visibility trait, as its products’ primary coating material. The Mil-I-46058C, IPC-CC-830, and RoHS Directive 2002/95/EC packaging specifications are additionally met.
Meanwhile, shock and vibe metrics are tested to the IEC 60068-2-27 and IEC 60068-2-6 standards, with custom tolerance tests run when requested.
And, as mentioned, there’s no sample testing here. “We do 100\% testing,” Van De Graaf asserts, “so that nothing the customer receives will be DOA. It also confirms it’s not going to fail the first time they boot up and run it in an extended temperature range. Some organizations only do a small sample testing, then certify the product and say they all can be used. But doing a small sample testing is not a valid way to say ‘This can withstand extended temperature ranges.’”
And, she adds, honesty is still the best policy when it comes to converting x86 products into the industrial range: Kontron only performs 100\% screen processing on commercial-to-industrial products if it's feasible; otherwise, Van De Graaf tells the customer it just won’t work. “For example, the Intel® Core™ 2 Duo SP9300 – We won’t put it into industrial temp designs or testing because we already know that one runs too hot. It would fail even in a screening format. Even some of the higher-end Core™ 2 Duos – there are some flavors we will not do a screening on because we know they will fail.” The result: back to the proverbial development “drawing board” for a new design plan.
But there’s always the hope that an ideal scenario arises where all industrial-temp wares can be used, without transforming anything commercial-grade into rugged. Recently, Kontron realized the dream with its first “by design” aka all industrial-temp components product: the microETXexpress-XL, a Computer-on-Module featuring the relatively new industrial-temp Intel® Atom™ Z520PT processor and US15WPT system controller hub, designed for use in mobile warfighter, public transportation, and outdoor POS applications. [“By design” is not to be confused with the “guaranteed by design” conversion theory described earlier].
If such innately and completely industrial designs were possible all the time, ruggedizing commercial components or designs would become a thing of the past, but is that feasible? What is holding processor vendors back from providing more industrial temp versions of their products?
Written by Sharon Schnakenburg-Hess, an assistant managing editor at OpenSystems Media®, by special arrangement with the Intel® Embedded Alliance.
- “When failure is not an option: Test and qualification help ensure reliability in mission-critical environments,” by Doug Patterson, Aitech Defense Systems, VME and Critical Systems Magazine, April 2009, www.vmecritical.com/articles/id/?3888
- “Commercial Off The Shelf (COTS) Configurable Systems and Modules,” Kontron, March 2010.
- “COM designed to meet the environmental challenges faced by outdoor POS systems, public transportation vehicles, mobile warfighter and more”, Kontron, Jan. 2010.