Search
Close this search box.

Mastering the Skies: The Science of Aerospace PCB Assembly

Mastering the Skies The Science of Aerospace PCB Assembly

Aerospace PCB assembly must meet stringent requirements, which include high reliability and long service life. We discuss the unique requirements of the aerospace PCBA and its example applications.

What is Aerospace PCB?

The aerospace PCB is a printed circuit board for air and spacecraft applications. It can be a PCB for satellite and navigation systems, civil aviation, military aircraft, or space shuttle electronics.

The board supports various electric and electronic systems like audio, lighting, and communication in these uses. Others include electric actuators, engine control systems, and instrumentation.

The aerospace board must remain operable in harsh conditions. For instance, it should not break down in extreme heat or disassemble when exposed to vibrations. These and other requirements are discussed below in detail.

Examining a mil-spec avionics PCB assembly
Examining a mil-spec avionics PCB assembly
Resource: https://www.youtube.com/watch?v=2pqLxqhMlpc

Aerospace PCB Assembly Unique Requirements

Aerospace circuit boards leave no room for design or manufacturing mistakes. Industry standards, therefore, demand the following for this PCB assembly type.

Environmental Resilience and Protection

Environmental resilience is a significant requirement. That’s because the boards operate in environments that subject them to vibrations, higher radiation levels, temperature extremes (-40°C to 150°C), high humidity, etc.

High Reliability and Longevity

Some space electronic systems are impossible to repair or too costly to fix. Their failure can, therefore, cause catastrophic losses. That calls for high durability levels. Here, we are talking about 5-10 or more years of useful service life.

Size and Weight Reduction

Aerospace applications require small-sized, lightweight components. A space-qualified PCB is, therefore, a high-density type, thin and sometimes flexible for compactness and enhanced adaptability.

A section of an aerospace PCB
A section of an aerospace PCB
Resource: https://scitechdaily.com

Overcoming Aerospace PCB Assembly Challenges

The aerospace PCB manufacturer follows the best design, fabrication, and assembly practices when making aircraft and spacecraft systems circuit boards. To overcome application challenges, they employ the following strategies.

Use of High-Performance Materials

FR408 replaces the traditional FR4 in a space-grade PCB, offering more excellent heat and flame resistance. Other substrates include GRP (glass-reinforced plastic) and ceramics or aluminum (and polyimide in the case of flexible boards).

Anodized aluminum takes the place of copper, conducting up to 10 times more heat away. The surface of the PCBA is coated with a high-quality conformal film, such as ENIG or HASL, and sprayed with acrylic for complete protection.

Thermal Management Techniques

In addition to using heat-resistant materials, the aerospace PCBA incorporates various thermal management technologies.

Heat sinks help dissipate heat and effectively cool high-temperature components like microprocessors. Cooling fans are also helpful, especially when other methods are inadequate.

Other techniques include thermal vias and heavy copper traces (2-4 oz) for improved heat conduction. During the design phase, spacing components enhances the loss of heat.

Rigid vs. Flex PCB

Rigid circuit boards are robust and preferred when sturdiness is paramount. Flexible PCBs are sometimes preferred because aerospace applications expose the boards to intense vibrations.

Flex boards also fit into tighter spaces and are lightweight, making them even more suitable for aerospace use. Sometimes, the usage situation requires a rigid-flex board. This type offers the best of both worlds.

Proper Routing and Layout

PCB design for space applications differs slightly from the conventional board. It includes highly optimizing traces for signal transmission, EMI protection, and current carrying capacity.

Measures include shorter traces to enhance signal integrity, larger ground planes, and separating high and low-frequency traces and other components.

It’s also common practice to protect the board from radiation using EMI shielding components such as EMI enclosures made of aluminum or other materials, conductive films, and several different materials.

SMT vs. THT Assembly

Through-hole assembly provides more robust connections than surface mount technology, proving higher reliability in extreme vibrations. It also allows large-sized or heavier components to attach to the board firmly for a very long time.

The SMD (surface mount device) method is sometimes necessary, mainly when producing high-density PCBs for advanced electronic systems or smaller spaces.

In other words, the technique depends on the anticipated usage conditions, with higher vibrations necessitating thru-hole components. SMD offers the benefit of higher-density circuits and better thermal performance.

Testing an aerospace circuit board for vibrational resilience
Testing an aerospace circuit board for vibrational resilience
Resource: https://www.mdpi.com

Importance of Rigorous Testing for Aerospace PCB Assembly

The aerospace, defense, and similar circuit boards undergo rigorous testing. The tests check the boards for defects, confirming their quality and dependability in mission-critical applications.

Automated equipment is necessary to minimize human errors. High-resolution cameras scan the board for surface defects by analyzing the images using computer software.

To detect hidden flaws, 2D and 3D X-ray equipment take cross-sectional images of the board and feed them to a computer program for analysis. That allows the testing expert to view the board’s internal structure in real-time.

Other methods include in-circuit or functional testing. Because it operates in harsh conditions, the board also undergoes the burn-in test when checking it for design and fabrication or assembly defects.

Flight control PCB assembly for UAV (unmanned Aerial Vehicle)
Flight control PCB assembly for UAV (unmanned Aerial Vehicle)
Resource: https://www.researchgate.net

What are Aerospace PCB Assembly Standards?

Various aerospace PCB design standards govern its production, ensuring unique qualities, environmental resilience, and durability. Unlike other board types, for example, the aerospace circuit board and assembly meet the IPC Class 3 standards.

These standards define reliability needs and include manufacturing and testing requirements. Another essential standard for air and space boards is the AS/EN 9100 by the International Aerospace Quality Group.

This standard is related to ISO 9001 but more specific to space application circuit boards. Several other reference standards are available. They mainly specify general requirements for printed circuit board productions.

Aircraft circuit board (radar altimeter)
Aircraft circuit board (radar altimeter)
Resource: https://www.youtube.com/watch?v=IdSUTiFO150

Conclusion

Aerospace PCB assembly demands are strict, with no room for design or fabrication flaws. They include the ability to withstand demanding environments involving extreme temperatures and higher radiation levels. The PCBA must also meet industry standards, such as IPC class 3 and AS/EN 9100.

Share:

Table of Contents