Design Guidelines to Avoid the Grounding of Your Aerospace PCBs

November 14, 2018 , in Blog

Space Repair Service Representative: Hello. How may I help you?

Satellite Service Operator: One of our satellites is malfunctioning.

Space Repair Service Representative: I understand. We can get that checked out for you.

Satellite Service Operator: How soon could you do that?

Space Repair Service Representative: We can have someone up there on Thursday?

Satellite Service Operator: That would be great! Thank you.

The above conversation may seem like science fiction, but in the near future, it will be science fact. To date, only the Hubble Space Telescope and International Space Station have received repairs while in orbit. Yet, there are companies in the U.S. and U.K. with plans in the works to start in-orbit repair services like refueling and repositioning within the next decade. This will be a revolutionary step forward for the aerospace industry; however, it will be some time before space servicing capacity will be adequate enough to prevent a large number of satellites from winding up as floating debris or falling back to earth. Of the over 8,000 objects that have been launched historically, there are presently nearly 5,000 satellites (approximately 40% being active) orbiting the earth. That number is increasing every year1.

This reality places significant pressure on the design and development of aerospace systems, electronics and PCBs. In fact, it is a major catalyst for the strict regulations and standards that have been put into place for the aerospace industry. Failure to adhere to these rules may result in your aerospace product prematurely failing or unable to get off the ground at all. There are some essential tips that you should employ when developing boards for aerospace platforms. Even so, navigating through the regulatory requirements can seem like walking through a minefield with few safe places to step. Fortunately, there a set of design guidelines that, if followed, will help you avoid the grounding of your aerospace PCB.

Design Guidelines for Aerospace PCBs

As with all board designs, the ultimate objective is to end up with a quality product that performs as intended over its expected lifetime. Aerospace PCBs are no different, albeit there are more strenuous conditions such as harsh operating environments and the inability to perform maintenance and repairs. As a result, designing aerospace PCBs requires more emphasis to be placed on the overall manufacturing process. Let’s discuss the design guidelines that define the most important avoidances for your board fabrication, component selection and acquisition, and PCB assembly.

What to Avoid for Board Fabrication

🚫 Low-quality materials

Although material selection directly impacts overall cost, it is important to ensure that your boards meet or exceed the applicable rigid, rigid-flex or flex standards as well as all thermal and electrical requirements for reliable operation.

🚫 Inadequate spacings, clearances and drill holes

These specifications should always be guided by your CM’s design for manufacturing (DFM) guidelines. However, meeting these may not be sufficient for special board types or non-form factor designs and additional constraints may be necessary. Be sure to discuss this with your CM to ensure that your specifications meet your design intent.

🚫 Inconsistent stackups

Unless you want to risk sacrificing the integrity of your board, you must address certain important PCB stackup considerations during design. In addition, your PCB stackup and choice of vias significantly impact your signal flows. Neglecting the latter will not prevent your board from being fabricated but may severely impact your PCB’s performance.

What to Avoid for Component Selection and Acquisition

🚫 Counterfeit components

The most serious threat to safe and reliable deployment and operation of aerospace systems probably comes from targeted or inadvertent utilization of counterfeit components. At the minimum, the detection of these components in your products by aerospace customers will increase regulatory scrutiny of your supply chain; in the worst case scenario, you may be blocked from supplying the industry at all.

🚫 Low-quality components

Counterfeit components may be of inferior quality and this could be the case for properly acquired components as well. Therefore, you should institute steps to optimize component selection and ensure that your component meets the performance criteria you require.

What to Avoid for PCB Assembly

🚫 Inaccurate footprints

The accuracy of the placement of your components during PCB assembly is directly correlated to the accuracy of the footprints in your PCB layout. You should follow board layout tips in line with your CM’s capabilities. However, note that your CM is typically not privy to your circuit’s operation and will most likely be unable to identify errors like incorrect component locations that can severely affect your board’s functionality.

🚫 Unclear or ambiguous silkscreens

Along with accurate footprints, an accurate silkscreen, including accurate reference identifiers, pin 1 and polarity indicators, is necessary to ensure that your CM properly aligns your components. Moreover, there are regulations that govern where logos and other markings may be placed for aerospace components.

🚫 Poor quality control

In order to supply systems, electronics, and PCBs to the aerospace industry, you are required to have in place a well-defined and documented quality management system (QMS). Your ability to meet the QMS standard depends not only on your in-house quality management but also on the quality control instituted by your CM.

By employing the above design guidelines, you will avoid the most common mistakes that could delay or ground your aerospace PCB design. PCB design and development for the aerospace industry is heavily regulated and requires you to take steps to ensure your CM is qualified for critical system PCB manufacturing.

Tempo Automation employs advanced board fabrication, component validation and PCB assembly equipment and processes to ensure that your boards are of high quality and precisely meet your design specifications. We are also committed to working with you beginning from day one of design to help you meet your aerospace development requirements.

Tempo‘s Custom Avionics for PCB Manufacturing Service
  • Accurate quote in less than a day.
  • DFM support from Day 1 of design.
  • Entire turnkey PCB manufacturing in as fast as 3 days.
  • Manufacturing processes that support your AS9100 Quality Management System Requirements.
  • Sources components from the most reputable suppliers in the industry to reduce procurement time and help with component security.
  • Performs multiple automated inspections during PCB assembly to ensure PCB quality for prototyping.
  • Design testing capabilities; including Flying Probe.

And to help you get started on the best path, we furnish information for your DFM and enable you to easily view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.

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 things to avoid in your design guidelines for aerospace PCBs as well as things to make sure to include, contact us.

1 According to the Index of Objects Launched into Outer Space maintained by the United Nations Office for Outer Space Affairs. Accessed 10/7/2018

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