ADVANCED MILITARY PCB ASSEMBLY
The military has always connected cutting-edge technology to run successful campaigns and protect our shores. Since the 20th century, that technology has included top-of-the-line military and defense printed circuit boards.
Printed circuit boards for military and defense are often held to a higher standard than ordinary printed circuit boards because their role is so crucial, and they will be subjected to such harsh conditions. Military grade PCBs are the toughest, most efficient and most reliable printed circuit boards on the market.
Applications and Types of PCBs for Military and Defense
Military and defense PCBs can include printed circuit boards for naval operations, aviation, general defense and even space applications. Because military printed circuit board applications are so varied, it's important to have access to a variety of PCB types so that you can be sure your military and defense PCBs will be appropriate for the electronics that use them.
Applications that use military PCBs can include:
- Power supplies for the AWACS-Airborne Warning and Control System — the "Eye in the Sky"
- Auxiliary power units for radar control systems
- Radio communications systems
- Control tower systems
- LED lighting systems
- Firearms and explosives testing equipment
- Underwater navigation systems
- Jet instrumentation
- Jamming systems
- Electronic countermeasures
- And many more
These military printed circuit boards will often be subjected to high pressures and stresses, meaning they will frequently require high-temperature substrates like temperature-resistant laminates, copper or aluminium. Military PCB manufacturers must produce PCBs that will resist heat-induced oxidation and effectively dissipate heat in a low-weight design.
Circuit Boards for the Aerospace Industry
The aviation industry is one division that requires sturdier PCBs than those required for normal ordinary gadgets. The components utilized in planes, space transports, satellites and control towers have to be extremely solid in extraordinary conditions. They’re exposed to a few unordinary circumstances that would put more push on standard PCBs than they seem handle. And in case these basic components fall flat, the results might be disastrous.
That’s why circuit board producers take extreme precautions and use extra durable materials when it comes to aerospace. Advances in circuit boards benefit the aerospace industry by making it safer and more efficient.
Here’s how aerospace circuit boards withstand some of the harsh conditions they’re exposed to.
In outer space, electronics could be exposed to temperatures as low as negative 150 degrees Celsius. In the vacuum of space, there is also no air to transfer heat, so the only way to transfer it is through radiation.
Manufacturers use certain high-temperature laminates, copper and aluminium substrates in aerospace PCBs so that they can survive these extreme temperatures. Thermal compound is also often used to insulate heat from transferring to other electronic parts.
Components may be set approximately 20 thousandths of an inch from the board’s surface, or space may be used to facilitate thermal dissipation of heat. In aviation, fans may be used to get rid of extra heat.
Heat can also lead to oxidation. Using anodized aluminium can eliminate the problems that this might cause.
Electronics used in the aerospace industry can also be exposed to mechanical abuse like excessive shock and vibration.
So that PCBs can withstand these sorts of conditions, producers now and then modify the design of the boards. A few utilize pins that are pressed into the board to help hold components in place, as opposed to utilizing soldering. In some cases, engineers combine pins and soldering for extra security.
Some of the strategies for making PCBs more safe to high or low temperatures also have applications for securing against shock and vibrations. Applying warm compound to a board can offer assistance reduce the effect of fluctuations. Leaving a little space between components and the surface of the board can also make a few help of the stretch on the PCB.
PCBs used in outer space have another somewhat unique challenge to overcome. The higher levels of radiation in space can cause damage to equipment if it’s not suited to tolerate its effects.
Manufacturers attempt to shield electronics from radiation using various materials. They also make components smaller, so that are fewer pieces that risk radiation. They also build in backups so that a single radiation event doesn’t disable an entire operation.
Antifuse technology, which creates permanent routes that can conduct electricity between transistors, has been found to be more resistant to radiation. Other types of circuits have been made more resilient by using thinner layers of material.
In aviation, radio waves must be used to communicate, so it’s crucial that signals can be transmitted without becoming degraded in any way.
To make sure that radio communications get through properly, manufacturers must place shielding in strategic places on the PCB and sometimes use antennas. Making transmission lines as short as possible can also help ensure that radio communications are correctly transmitted.
The prevailing mounting technologies known in the current PCBA (Printed Circuit Board Assembly) industry are of two types:
Thru-Hole technology is applicable on PCB assemblies that contains large mechanisms such as capacitors, or coils that are to be accumulated.
Surface Mount Technology:
It is called SMT for surface mounting. It is usually applicable on smaller components and IC’s (integrated circuits), components smaller even sometimes than size of a pencil point.
Surface mount assembly refers to the mounting process that surface mount components or surface mount devices (SMDs) are mounted on bare board through solder paste that plays a role as glue to stick surface mount components to board. The general process of surface mount assembly contains solder paste printing, components mounting, automated optical inspection (AOI), reflow soldering, AOI or AXI etc.
Application of Surface Mount Assembly
Developed as early as 1960s, surface mount technology has been popular since 1980s. Up to now, it can be concluded that majority of electronic products are assembled through the application of SMT. Components accessible to SMT are smaller in size and they can be mounted on both sides of a board so surface mount assembly performs better on high-density and miniaturized products. Additionally, low weight and miniaturization are two leading trends of future electronic products. Thus, SMT will be increasingly more accepted by the industry.
Surface mount devices cover such wide classifications that it's almost impossible to list them one by one. However, it's not a tough job to summarize their characteristics that will give you better understanding of surface mount assembly:
a. Shorter leads. Different from through-hole components with leads, surface mount components or devices carry shorter leads, leading to stronger electrical connection.
b. Smaller sizes. SMDs are much smaller than through-hole components and some of them are even too small to be seen by naked eyes, such as package 01005. Smaller sizes of SMDs result in more space saving on bare board.
c. Higher reliability. SMDs depend on solder balls below to capture better bonding capability and reflow soldering makes them tightly soldered on board, dramatically improving reliability and repeatability.
Advantages and Disadvantages of Surface Mount Assembly
SMT is more accessible to smaller PCB sizes, higher-density components and more board surface area saving. Due to un-necessity of drilled holes, SMT provides lower cost but shorter manufacturing time. In the process of PCBA, SMT mounting speed can reach thousands or even tens of thousands of chips per hour while through-hole mounting fewer than one thousand chips. Furthermore, solder joints through reflow oven feature higher reliability and repeatability and it has been testified that SMT performs more solidly when vibration takes place.
However, once components susceptible to mechanical stress are assembled by SMT, its reliability may be reduced.
We use circuit boards every day, and they’re essential to most of our electronics. Our gadgets don’t usually have to endure any extreme temperatures or radiation though. When it comes to printed circuit boards for the aerospace industry, they need to be able to withstand a lot more.
Advances in circuit board design and production have allowed the aerospace industry to be advanced. Without aerospace circuit boards that can deal with radiation, we may not be able to explore deep space or send satellites to orbit the earth. If circuit boards used in jet planes weren’t able to withstand extensive shock and vibrations, they might become damaged, which could create a dangerous situation.
As circuit board manufacturers continue to innovate new ways to make PCBs more versatile, sturdy and reliable, the aerospace industry will benefit as well. Aerospace equipment will be able to use PCBs in more efficient ways, need maintenance less often and run more reliably and efficiently. Although circuit boards are just one small part of the aerospace industry, they’re an important one that can have widespread impacts across the industry.