The increased focus on network-centric warfare in today's military operations has expanded the use of embedded systems in the deployment of mobile, mission-computing and high-performance applications. These embedded systems must be rugged enough to handle the toughest environmental conditions such as extreme temperatures, yet be efficient enough to meet application needs for power and heat dissipation. For many embedded applications in the mobile and mission-computing segments, HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screening) testing is a necessity. Given the recent shift from internal, proprietary developments to solutions built from commercial off-the-shelf components, the military is now looking outside of its engineering ranks to guarantee that its components are rigorously temperature tested.

Aerospace and Defense end users are requiring Original Equipment Manufacturers (OEMs) to adhere to HALT/HASS testing methodologies in order to ensure greater levels of product quality and reliability. In today's economy, spending time and resources performing these tests, not to mention investing in the test equipment itself, could be a weighty proposition. Companies may find it difficult to balance the upfront commitment with smaller budgets and reduced manpower. However, unexpected failure modes and/or high failure rates can result in expensive field service calls or significant downtime. As a result, product failures usually end up costing manufacturers more in the end.

For OEMs, finding a partner to perform HASS/HALT testing in-house is crucial to managing testing expenses. Equally important is finding a vendor that utilizes best testing practices, including extended temperature testing. Given the cost and security implications associated with military deployments, it is important to test at a wide temperature spectrum and high vibration levels upfront. By partnering with a HALT/HASS testing specialist, OEMs can reduce development time as well as deploy military applications quickly and cost-effectively with improved performance.

COM Express Can Take the Heat

The standards-based, highly reliable architecture of COM Express is an ideal fit for many military applications in the mobile and mission-computing segments, including ruggedized multipurpose computers and unmanned vehicles. COM Express is the PICMG specification for Computer-on-Module, and solutions based on this form factor reap the benefits of modularity, scalability and ease of upgradeability. In addition, COM Express-based solutions are highly integrated and compact, delivering high-performance processing within a small, low-power embedded form factor. Those aspects make it an ideal platform for portable, battery-powered applications and helps designers meet the unique enclosure needs for aircraft and ships. COM Express solutions leverage the latest Intel mobile processors and chipsets, are engineered to support current performance requirements such as PCI Express and SATA, and most importantly, are rugged enough to handle the harshest environmental factors.

Systems like Unmanned Ground Vehicles (UGVs) (Figure 1) or man-wearable computers must be ruggedized to stand up to extreme temperatures, shock, vibration and G-forces, in the air, under water or on the ground, and must perform reliably under extreme temperatures and vibration conditions in the field. Portable and in-vehicle devices are additional applications that can benefit from a COM Express embedded component. Mobile computing applications and wearable units must be lightweight, rugged and perform reliably under extreme temperatures in the field.

Testing Rugged Form Factors for Tactical Apps

Though there are varying degrees of ruggedness for different military embedded applications, HALT and HASS are advanced approaches to testing in the design stage and manufacturing stage to ensures that solutions are capable of operating at extended temperatures under harsh vibration reliably.

The first step in extended temperature testing is to demonstrate a product's capability by employing HALT (Highly Accelerated Life Testing) techniques. Figure 2 shows a HALT chamber containing a chassis/board-level system under test. HALT is used in the design phase to explore and maximize the full limits of a product design. This testing consists of a stepped thermal and vibration stress process during which the actual limits of the design and component performance are determined. As Figure 3 shows, HALT covers six degrees of vibration movement. As failure modes are discovered, they are corrected by design or component improvement until no further improvement is practical or is limited by the fundamental limit of the underlying technologies. By establishing that the design and components are capable of operating not only to the extended temperature specification but well beyond, HALT demonstrates the true operational limits of the product. The concept and execution of maximizing the design margin is critical to successfully producing reliable, extended temperature products.