Flex PCBs for Aerospace

When you design a printed circuit board (PCB), there are many options to consider including rigid, flex, and a hybrid rigid-flex PCB. Rigid-flex PCBs offer the best of both worlds – they provide excellent mechanical integrity and connectivity, while also offering improved resistance to vibrations and shocks, EMI, and signal loss. They also reduce assembly costs and weight by eliminating the need for connectors and cables.

The biggest benefit of using a flex pcb in aerospace applications is that they take up less space. In addition, they are often thinner than the same circuit on a rigid substrate and are therefore lighter. This reduced weight is particularly important in aerospace systems, where every ounce counts. Even though everything is weightless up in space, launching a rocket into orbit still requires significant energy, and the more weight that can be saved, the better.

Another advantage of a flex pcb is that it allows for more complex designs. The flex layers can be folded, curved, or warped to fit the mechanical constraints of a device’s enclosure or shape, making it possible to use smaller parts and save space. This flexibility also makes it easier to accommodate thermal management features, which can help dissipate heat more efficiently.

Flex and rigid-flex pcbs can be used in consumer electronics, automotive, medical devices, robotics, or aerospace applications, where space is limited or performance requirements are high. In these applications, flex and rigid-flex PCBs can provide improved EMI performance and signal integrity, as well as resistance to vibrations, shocks, temperature changes, or environmental agents.

Flex PCBs for Aerospace Applications

Unlike standard PCBs, which have a fiberglass or metal base, the core of a flex pcb consists of a flexible polymer. The most common is a polyimide (PI) film. PI film is a thermosetting resin, which means it remains flexible after it has been heated. This type of flex PCB is more durable than other types and offers superior abrasion and humidity resistance. It can be made with multiple layers, and the conductive material traces can be routed on either side of the PI film.

A flex circuit can be printed in as many layers as the design requires, but most use just two layers. This is because higher layer counts can lead to stress points that weaken the flex PCB when it is bent or twisted. To avoid this, it is recommended to route traces perpendicular to the bend line and use fillets to connect them to the vias or plated through-holes. This ensures that the traces will not break when the board is manipulated.

The production process of a flex or rigid-flex PCB begins with designing the layout and stack-up, which involves specifying the number of rigid and flex layers and their configuration. The copper traces are then printed on the layers, and holes are drilled to connect them. The layers are then plated with copper and a solder mask is applied to protect the copper from contaminants. Finally, the flex and rigid layers are bonded together using specialized adhesives, creating a robust and flexible composite structure.