Flex PCBs Be Used in Aerospace
The most popular application of flex circuits is in satellites, which are used to transmit TV and internet signals to homes and businesses. They are also used in mobile phones and fleet vehicles, allowing for communication between devices and people. In fact, many technologies that were developed for space exploration by NASA are now used in everyday consumer products such as memory foam pillows, for example. The base material of rigid printed circuit boards is a woven fiberglass impregnated in epoxy resin. While this has some flexibility, it is not enough for most flex applications. This is why most flex circuits use a polyimide base film.
Polyimide is extremely flexible, very tough (you can’t tear it or noticeably stretch it by hand), and incredibly heat resistant. This makes it highly tolerant to product assembly processes like solder reflow cycles and relatively stable in expansion and contraction due to temperature fluctuations. It is also a good thermal conductor, making it a great choice for flex circuits.
Another advantage of a flex pcbs is that it can be made in a wider range of shapes than a rigid board. This allows for the creation of more complex electronic designs that would not be feasible with a rigid PCB. It is also much lighter than a traditional PCB, which can be an important consideration in some applications.
Can Flex PCBs Be Used in Aerospace Applications?
Whether it is used in a satellite or in any other application, a flex PCB must be able to withstand the environmental conditions it will be subjected to. In space, the environment is harsh and unpredictable. The flex circuits used in satellites are designed to be flexible, so that they can absorb the shocks and vibrations of space travel. They must also be able to withstand the constant bending and stretching of the spacecraft itself.
In order to make a flex circuit more durable, it is recommended to stagger the traces instead of stacking them one on top of the other. This will increase their strength and prevent them from cracking during the flexing and bending process. Another tip is to avoid using solid copper for the pads on a flex PCB, and instead opt for hatched copper or a combination of plated through holes and solder masks. This will reduce the amount of copper needed, which can help to keep the PCB lighter.
It is also recommended to add a stiffener to the PCB in areas where it is expected to be bended or flexed. This will give it additional support and increase its durability. Stiffeners can be made from a variety of materials, but the most common is Kapton. It is a specialized flex polyimide that has been extensively tested in space, so it is known to be resilient and reliable. Lastly, it is recommended to test the flex circuits for electrical faults before shipping them out to customers. This can be done based on a final inspection perspective and will ensure that the flex circuits are free of internal faults and contact points that could cause problems when used in a customer’s device.