Gazing at a clear sky at night can be mesmerizing, perhaps even therapeutic. From a vantage point safely here on earth, space seems serene and safe. However, the opposite can be true for spacecraft, orbital and interplanetary. The space environment can subject mechanical and electrical systems to many hazards. These include radiation, extreme temperatures and significant vibratory forces during flight.
Electronic systems and PCBAs are typically somewhat shielded from a spacecraft’s external effects, but they are not immune to the impact. For example, some radiation particles can penetrate virtually any material and pose a threat to circuit boards, primarily if radiation-hardened electronics are not utilized. These hazards extend beyond individual boards and components to the greater electronic systems, meaning your aerospace PCB connectors’ choice is critical to system performance and reliability.
Let’s look at the challenges for circuit board interconnectivity about spacecraft and how to make the best selections for your aerospace PCBA design.
Challenges of PCB Connectivity in Space
Before discussing specific challenges for aerospace PCB connectors, it is helpful to understand the environment in which space vehicles operate. Space includes all elevations above the earth, whether within the earth’s atmosphere or beyond it. The earth’s atmosphere consists of five layers. All of these, except the mesosphere, which extends from 50 km (≅ 31 mi) to 85 km (≅ 53 mi), routinely consists of platforms that contain avionics or electronics systems aboard aircraft, spacecraft and satellites—the most common aerospace vehicle. Each has specific environmental conditions, some of which are hazardous.
Hazards for PCBA Connectors in the Space Environment
There are three primary hazards for platforms and the electronic systems--boards and connectors--that comprise them when operating in space. These are vibration and shock, temperature extremes and radiation.
- Vibration hazard
Vibration is a concern for all space vehicles as the most shock occurs during launch. The most damaging effects are breakage or material deformation (which may be instantaneous) and material fatigue that may have long term impact.
- Temperature hazard
For board connectors, the hazard of extreme temperature is most often more of an internal issue than an external. For example, during the launch, temperatures greater than 3,000 °C (or nearly 6,000 °F) may be present near the rocket engine. These exceed the PCBA temperature limits for most materials used in aerospace electronics systems. Therefore, isolation and thermal control systems are critical onboard space vehicles.
- Radiation hazard
Probably the most dangerous hazard in space is high-energy ionizing radiation, which can be present at any of the earth’s atmospheric levels and beyond. Certain radiation particles can penetrate virtually any material and cause charge buildup on conductive elements or atomic dislocation to impact device functionality. Similar to vibration and shock, there may single event effects (SEEs) or issues that evolve.
Once the hazards present for aerospace PCB connectors are understood, a set of guidelines will help you make the best selections.
How to Choose Your Aerospace PCB Connectors
There are many connectors for PCBAs available, and selecting the best type for your application is not a simple proposition. Connector selection cannot be made in isolation. It is imperative to know the connector type for the PCBA(s) or electronic devices with which your board must attach to optimize signal TX/RX and power transfer. There are also physical concerns, such as enclosure clearances and aperture alignment for wiring, cabling, or the connector.
Additionally, as connectors are circuit board components, they must adhere to aerospace industry standards for PCBA manufacturing. This adherence includes ensuring that adequate testing requirements for space grade connectors are met. Therefore, the best means for choosing aerospace connectors for your design requires that you incorporate all of the following:
Considerations for Aerospace PCB Connector Selection
- Regulatory requirements
Connectors used on aerospace platforms must satisfy material requirements as stipulated by EIA/ECA-364-18B, mating and unmating force standards as defined by EIA-364-13E, continuity during mechanical shock as stated in EIA-364-27C and other testing regimens based on the installation environment.
- External environmental conditions
For external cabling and connectors, temperature range and radiation exposure are primary considerations.
- Internal environmental conditions
Internal environment concerns include temperature range, humidity, environmental EMI and external radiation that may penetrate the spacecraft’s interior.
- Operational requirements
For most space vehicles, repair or replacement of electronic systems, including connectors, is not possible. Therefore, well-defined lifetime operational requirements must be established and utilized in selecting the best connectors.
Operating in space can be hazardous; one must meet stringent regulations set forth by the aerospace industry. Primary considerations influencing your connector decision include evaluating the space vehicle’s internal and external environment and whether the PCBA is a part of a mission critical system.
In addition to the considerations above, component supply chain management can also be a significant concern.
|Tempo's Custom Avionics for PCB Manufacturing Service
At Tempo Automation, we work with the industry’s most reliable vendors and employ a digital data supply chain that tracks and monitors components from the vendor and through the build process. This reliable supply chain ensures component availability, security and meets aerospace regulation QMS tracking requirements.
To help you get started on the best path for your board build, we furnish information for your DFM checks and enable you to view and download DRC files easily. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in different CAD formats and Excel.