Today, the aerospace industry offers many opportunities for excitement. For example, NASA is planning another crewed mission to the moon—almost 50 years after Apollo 17. If that was not enough, there is also a planned mission to take human passengers to Mars.
Amidst the buzz surrounding these space ventures, we can overlook the unprecedented development and usage of CubeSats. These nanosatellites have revolutionized the launch cycle even beyond new space capabilities and lowered the cost of sending objects into space. Although, these space platforms are game changers that will significantly influence satellite activity for the foreseeable future, they are still subject to the hazards of entering and operating in the space environment—as are the electronics and PCBAs onboard.
Testing provides the most common method of proving that a system space-ready. Among the array of tests, CubeSat vibration testing is arguably the most important.
Requirements for Building and Deploying CubeSats
One of the advantages of developing CubeSats is the use of a well-defined geometry. Irrespective of platform size, it is always a factor of the base unit dimensions and architecture. The base unit, or IU CubeSat, has dimensions of 10 cm x 10 cm x 10 cm. Along with the base unit, other common sizes are 2U, 3U and 6U. When building CubeSats of any size, a set of specific requirements, as listed below, must be followed.
CubeSat Building Requirements
- General requirements
To qualify for launch, CubeSats must meet requirements that define limits and constraints on materials, propulsion and payload.
- Mechanical requirements
The rules here apply to physical dimensions, mechanical structure (especially rails), and material types.
- Electrical requirements
These include the important provision that a CubeSat power supply shall be off and isolated from any other active electrical/electronic devices, such as a real-time clock or RTC, from pre-launch until the system is deployed in orbit.
- Operational requirements
Operational requirements describe how a radio frequency license shall be secured. Additionally, they cover the schedule for initiating deployments—such as booms and antennae—as well as other operational considerations to ensure the safety of other CubeSats and limit space debris.
- Testing requirements
All CubeSats must satisfy appropriate testing requirements. However, these requirements may vary and are primarily mission-specific. As such, it is the responsibility of the Mission Integrator to specify the testing regimen the CubeSat must follow. However, any testing requirements set forth by the launch provider take precedence over other environmental testing concerns.
Additional information on all CubeSat requirements can be found at cubesat.org.
CubeSat Testing Regimen
The CubeSat testing regimen shall be either qualification or protoflight and with the flow as shown in the figure below.
CubeSat and Deployer Testing Flow
As illustrated above, vibration testing is an integral step in showing that a CubeSat is space-ready. However, no standard test process currently exists for CubeSats, and the specific vibration testing performed is determined by the Mission Integrator. Keeping with the goal of cost-effective space deployment, a team from Western Michigan is working to demonstrate the viability of utilizing a spectrometer with vibration test axes as a low-cost technique for CubeSat vibration testing. The method adheres to NASASTD-7001B, which sets the criteria for qualification and protoflight payload testing regimens.
How Does CubeSat Vibration Testing Impact PCBA Development?
Although CubeSats are much smaller than typical satellites, they operate in the same region of space. In fact, their smaller size makes them more vulnerable to shock from impacts with space debris. When performing vibration testing, all internal systems, boards and components are subject to the same level of structural stress, which is the maximum the CubeSat should be able to withstand. Therefore, PCBAs developed for installation on space deployment vehicles must be able to maintain structure, connectivity and component adhesion at the level set for the CubeSat. To meet this requirement, the following considerations should be included during development.
PCBA Development Guidelines for CubeSat Vibration Testing Requirements
- Use THT whenever possible
Through-hole components soldering connections are stronger and more durable than SMT joints; therefore, this characteristic should be leveraged for CubeSat boards, if possible.
- Use underfill or staking adhesives
Underfill and staking adhesives relieve some of the mechanical stress on solder joints during shock and vibrations.
- Ensure boards meet structural integrity standards
The structural integrity of the board construction is also important. Be sure to perform structural tests—like peel tests and other regimens to ensure stackups are well-bonded—on your boards.
- Apply coating
Typically, conformal coating can protect manufactured PCBAs from corrosion or contamination. Applying a protection method also strengthens the adhesion between the board and the components.
|Tempo's Custom Avionics for PCB Manufacturing Service
When building boards for aerospace systems such as CubeSats, employ guidelines like the ones listed above to ensure the nanosatellite’s ability to withstand the space environment as well as the testing regimens for flight qualification. At Tempo Automation, we have experience building boards for aerospace systems, local orbital deployment and interstellar travel.
To help you get started on the best path for your project, we furnish information for your DFM checks and enable you to easily view and download DRC files. 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 other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on how to ensure your boards satisfy CubeSat vibration testing requirements, contact us.