Both the military and aerospace industries require highly advanced electronics. Aerospace and military electronics require excellent reliability, quality, and compliance standards. Military and defense printed circuit boards are often held to higher standards than those regularly published because their work is critical and subject to stringent conditions.

In addition, military or aerospace PCB assembly requires the most complex and reliable printed circuit boards. In this article, we will look at various aspects of PCB assembly used in these two industries.

Military and Aerospace PCB Assembly

In addition to traditional design considerations for electrical equipment assembly, military and aerospace components require the following:

Allow additional clearance space when mounting heat-generating components to protect the board and other components from the heat.

Apply thermal paste where heat resistance is needed.

Pre-tin stranded and braided wires to improve solderability.

Solder press-fit components to mitigate vibration issues.
Double-check the heat settings (thermal profiles) for reflow and wave soldering procedures to ensure that components are not damaged by heat during assembly.
To protect the final product, use a high-grade acrylic-based spray to cover the PCB with a conformal coating.
Completed PCBs and assemblies are 100% inspected to verify quality.
The military has always combined cutting-edge technology to perform spectacular battles and defend our coastlines. Since the 20th century, this technology has come to represent top-notch military and defense printed circuit boards.

Similarly, the aerospace sector has also grown due to advancements in circuit board design and manufacturing. Unless we have aerospace circuit boards that can withstand radiation, we may not be able to explore deep space or launch satellites into orbit. If aerospace PCB assemblies cannot withstand high levels of shock and vibration, they may be destroyed, leading to catastrophic situations.

Design Considerations
These devices must be manufactured without flaws. They must operate without failure throughout their service life and under extreme environmental conditions such as extreme humidity, high or low temperatures.

Electromagnetic interference (EMI) and electromagnetic pulse (EMP) do not affect military and aerospace assemblies or military and aerospace PCB assemblies.

Applications of PCBA in Military and Defense
Military PCB assemblies may include printed circuit boards for marine operations, aviation, general defense, and space applications. Military and security printed circuit boards have many different uses, so it is essential to have a variety of PCB types.

Military PCBs are used in a variety of applications, including:

Radar control systems that require additional power
RF systems for transmitting radio waves
Control tower systems
LED lighting technology
Firearms and explosive detection equipment
Underwater positioning systems
Jet engine instrumentation
Contraband or jamming equipment
Countermeasures using electronic technology
Military printed circuit boards are often subjected to tremendous stress and strain, which requires the use of high-temperature substrates such as copper or aluminum PCBs. Military PCB assembly manufacturers must create panels that can withstand thermal oxidation, dissipate heat efficiently, and are lightweight.

Aerospace Industry Printed Circuit Boards
The aviation industry is one of the industries that requires PCBs to be more rugged than everyday electronics. Flight, space, and control tower electrical components must be extremely durable in harsh environments. Failure of these basic components can have serious consequences.

Therefore, aerospace PCB assembly manufacturers take extra measures and use more rugged materials in aerospace applications. The aircraft industry benefits from advances in circuit boards because they make them safer and more efficient.

See how aerospace circuit boards perform in the most extreme situations.

Extreme Heat
Electronic devices can be exposed to temperatures as low as -150 degrees Celsius in outer space. Even without any other means of heat transfer in the absence of an atmosphere, radiation is the only method available in this region.

Manufacturers use special high-temperature laminates, copper, and aluminum substrate PCBs in aerospace PCBs to withstand these extreme temperatures. Thermal paste is also often used to prevent heat from transferring to other electrical components.

Components can be placed 20 microns away from the surface of the board to improve heat dissipation, or additional space can be utilized. Fans on aircraft can dissipate excess heat. Oxidation can also occur due to heat. These problems can be avoided by using anodized aluminum.

Suspension Seizure
Mechanical abuse, such as severe pressure and vibration, can also cause problems for electronic devices used in the aviation field.

To ensure that PCBs can withstand such environments, PCB manufacturers adjust their designs from time to time. As an alternative to soldering, some manufacturers use pins to press components into the board to hold them in place. In some cases, engineers may mix pins and soldering for increased safety.

Some PCB temperature safety measures also help with shock and vibration protection. Applying heating compound to the board can help reduce the effects of fluctuations. Stretches on PCBs may also benefit from some space between components.

Radiation
PCBs used in space face a unique set of challenges. Devices that cannot handle the increased radiation levels in space are at risk of failure.

Manufacturers use a variety of PCB materials to try to protect circuits from radiation. They can also reduce component size, which reduces the number of parts that may be exposed to radiation. They have built-in backups if a single radiation event occurs, so the entire operation does not stop.

Antifuse technology has proven to be more resistant to radiation because it creates a permanent path for current between transistors. Thinner layers of material have been used to increase the resilience of other circuits in aerospace PCB assembly.

Electromagnetic Waves
On aircraft, radio waves must be used to communicate. Therefore, the signal cannot be damaged during transmission.

Shielding and antennas ensure that radio signals travel correctly through the PCB. Shortening transmission lines helps guarantee that radio information is accurately delivered.

Mounting Techniques
There are a variety of mounting methods available. Currently, there are two mounting technologies commonly used in the PCBA (Printed Circuit Board Assembly) business:

Through-hole technology: Through-hole technology can be applied to PCB components that contain a large number of mechanisms, such as capacitors or coils.
Surface mount technology: Surface mount is abbreviated as SMT. As a rule of thumb, it is best used for components that are smaller than the diameter of a pencil tip.

SMD: Assembling surface mount devices (SMD) on bare boards is surface mount assembly. Solder paste is used as a glue to fix surface mount components in place. Talking about the overall process of SMA (Surface Mount Assembly), it includes printing solder paste, mounting components, and automated optical inspection (AOI).
Use of surface mount components
Surface mount technology can be traced back to the 1960s and has become increasingly common since the 1980s. By now, it is safe to say that SMT has been used to manufacture the vast majority of electronic products. Surface mount assembly is more suitable for high-density and miniaturized products because SMT components are smaller in size and have multiple mounting options.

In addition, future tech products will be lighter and smaller, so the industry will gradually embrace SMT.

Characteristics of SMT

There are so many types of surface mount devices that it is almost impossible to list them all. On the other hand, summarizing their characteristics can help you better understand surface mount components for military PCB assembly or aerospace PCBA.

Shorter cables
Unlike through-hole parts with leads, the leads in surface mount components and devices are shorter, allowing for more secure connections.

Reduced size
Compared to through-hole components, SMDs are significantly smaller, and some are even too small to be seen by the human eye, such as package 01005. Smaller SMDs save more space on bare boards.

Higher reliability
The improved bonding ability of SMDs is partly due to the solder balls underneath.

Reflow soldering allows for tighter solder joints on the board, improving repeatability and reliability.

In short, smaller PCB size, better component density, and greater board area savings are all advantages of SMT. Since drilling is not required, SMT is less expensive and takes less time to produce.