For the aerospace and defense industry, electronic products must always perform reliably, especially when exposed to harsh or poor operating conditions. Hostile operating environments can be defined by parameters such as shock, vibration, temperature, humidity, or any combination thereof. Thankfully, there are reliable partners to help you ruggedize your electronic product for harsh environments found in a variety of markets, including aerospace, complex industrials, medical technologies, and defense. With practical design, manufacturing, and test development strategies, electronic products can be ruggedized for the most hostile environments to support critical applications for diverse markets.
Varying Requirements for Harsh Environments
The environmental extremes within harsh environments will depend upon the application, with some electronic and mechanical requirements more stringent than others. Electronic components, devices, and systems suitable for commercial applications are typically not rugged enough for industrial or military applications.
For example, commercial, industrial, and military electronic systems have their own temperature, humidity, shock, and vibration requirements. Applications may also be impacted by electromagnetic interference (EMI) and electrostatic discharge (ESD), requiring electronic designs with suitable electromagnetic (EM) protection in which EMI and ESD have minimal effects.
Challenges and Solutions
Extreme Temperatures
Operating temperature is often a starting point when qualifying electronic products for an application. Each of the three major market areas listed below has a different temperature range:
- Zero to 70 degrees Celsius for commercial products
- Minus 40 degrees Celsius to 85 degrees Celsius for industrial products
- Minus 55 degrees Celsius to 71 degrees Celsius for military products
Parts for those applications must be tested according to each temperature range since temperature-related failures can cause unacceptable mission and system risks. Outer space is often considered the harshest operating environment due to its vacuum, wide temperature ranges, radiation exposure, and spacecraft's shock and vibration. But terrestrial applications can also suffer stressful environmental conditions. For example, electronic sensors for motor-vehicle internal combustion engines must handle temperature extremes to 150 degrees Celsius and higher, beyond the temperature range of military systems.
When designing for military and aerospace applications, temperature is a critical factor to consider. Benchmark's typical MIL temperature range spans from minus 55 degrees Celsius to 71 degrees Celsius. We utilize Finite Element Analysis (FEA) during the design process to ensure our designs meet thermal and structural limits.
Temperature Chamber and Shock and Vibration Testing
By testing semiconductors and other electronic devices and components in temperature chambers, operating behavior and thermal impact on reliability can be studied for operating and storage temperature ranges of interest. Testing at elevated temperatures can also accelerate aging effects and provide insights into the expected operating lifetime of a device under test (DUT). Standardized testing that mimics harsh environments—such as highly accelerated life testing (HALT) and highly accelerated stress screening (HASS)—can improve reliability for an electronic design that must operate effectively in harsh environments.
Aerospace and other applications are often subject to excessive shock and vibration. Shock may result from an applied force or sudden change in the direction of a vehicle, while vibration can result from nearby mechanical equipment, such as motors. To ensure the reliability of electronic components, devices, and circuits in those applications, they can be tested according to a suitable standard—such as MIL-STD-810—to determine the effects of such parameters as mechanical shock and variable-frequency vibration. Testing is usually performed in a certified shock and vibration laboratory.
Understanding Materials
Preparing electronic equipment for harsh temperatures requires an intimate understanding of the thermal effects on various materials. Some materials can better withstand extreme temperatures than others. As an example, for semiconductors, for example, silicon carbide (SiC) and gallium nitride (GaN) substrates handle higher temperatures without performance degradation and failure than do gallium arsenide (GaAs) substrates. Understanding the behaviors of materials used in electronic devices, printed circuit boards (PCBs), and even in packaging can contribute to attaining the highest possible reliability in harsh environments. Some electronic products may require the integration of cooling systems. Still, alternatives to cooling systems must be considered where size and weight are critical—such as in reduced size, weight, and power (SWaP) designs.
Design and manufacturing of PCBs can also contribute to enhanced reliability under harsh operating conditions. Just as high-density interconnections (HDIs) help attain miniaturization for reduced SWaP designs, interconnection layout and placement can help counteract the effects of pressure, shock, vibration, and temperature on PCB electrical and mechanical stability. Hermetic-packaged devices and components provide protection in high-humidity environments but typically have a larger form factor than non-hermetic devices and may not enable reduced-SWaP PCBAs. Compact PCBA designs may require alternative approaches, such as system-on-chip (SoC) and multichip-module (MCM) devices that will allow hermeticity with reduced size for smaller PCBs.
Refining Ruggedization
Achieving electronic designs that can handle harsh environments requires components, devices, and circuit materials well suited to environmental extremes. The suitability of electronic components and devices for a set of harsh environmental conditions can be found through specialized testing, such as environmental stress screening (ESS), during which shock, vibration, humidity, and temperature are applied to a DUT during testing to determine levels at which damage occurs, or performance is degraded.
Benchmark — Designing Electronic Products for Harsh Environments
Protecting PCBs with Conformal Coatings
Benchmark starts our design process for durable PCB assemblies by carefully selecting circuit materials that are well-suited for the expected environmental factors, product technology, and application use. This analysis is a critical part of our design review process and allows us to evaluate the thermal and vibrational performance of our mechanical designs under appropriate power conditions.
We consider various environmental factors (such as temperature, shock, and vibration), RF performance, radiation, and the use of conformal coatings (e.g., acrylic, parylene, epoxy, polyurethane, silicone, or other specialty chemistries that are directly deposited across the PCB to protect it and its components from moisture, humidity, and temperature extremes). Additionally, we can utilize surface finishes like electroless nickel with immersion gold coating (ENIG) to increase the ruggedness and corrosion resistance of the PCBA.
Redefining Ruggedization
Benchmark has refined its ruggedization of COTS components and other electronic devices and assemblies through extensive design and manufacturing capabilities and by staking significant components to ensure stability in high shock/vibration environments.
These capabilities are backed by advanced test equipment and expertise to fully understand and optimize electronic products for the harshest operating environments. Analysis and test capabilities include Design Failure Mode and Effects Analysis (DFMEA) with temperature, humidity, shock, and vibration stress testing (to 2000 Hz) for industrial, military, and other applications, as well as:
| ESS Capabilities | HASS | Thermal Cycling |
| HALT | Mean-Time-Before-Failure (MTBF) Calculation | Vibration and Shock Simulation Analysis |
Benchmark also supports an extensive list of military and industrial test standards, including:
- MIL-STD-810
- MIL-STD-704
- MIL-STD-1275
- MIL-STD-461
- MIL-STD-901
Our expertise and experience in designing and manufacturing electronic products for harsh environments help eliminate defects that can emerge during manufacturing. The integrated approach to design and manufacturing yields low system failure rates with minimal in-field failures, which is considerably challenging for electronic applications that must function reliably in the harshest environments.
Your commitment to excellence propels the industry forward. Collaborate with Benchmark to create robust designs for challenging environments.
