The most common type of Printed Circuit Board (PCB) is rigid, but flex PCBs have been growing in popularity for designs that require flexibility and space optimization. In this article, we will explore the benefits of flex PCBs in aerospace applications and some of the key considerations when choosing between a rigid or flexible board for your design.
Rigid-Flex PCBs have a complex, multi-layer stack-up that includes copper traces, adhesives, laminates and polyimide materials. Rigid layers are typically made from standard FR-4 boards, and the flex layer is bonded to these layers using specialized adhesives. This makes the rigid-flex a durable, robust composite structure.
These flexible pcb board can be found in a wide range of applications. They are often used in devices that need to operate at high temperatures, or for long periods of time. They also need to be able to tolerate shock and vibration. Many of these types of applications are in military and aerospace industries, where reliability is critical to the success of the device.
Flex PCBs for Aerospace Applications
For this reason, PCBs for aerospace applications must be able to disperse heat quickly and efficiently. This is usually achieved by using heavy copper technology, and the use of thermal vias to transfer the heat to a large area of the board. In addition, the flex PCB must be constructed with a large radius to prevent stress and cracking, especially at corners. The bending of the flex layer is also a concern, and care must be taken to avoid 90-degree bends, as these can cause damage and short circuits. The flex layer should also be free of discontinuities such as vias, cut-outs and slits to reduce the risk of failure due to stresses caused by these features.
Another advantage of a flex PCB is its ability to reduce the overall weight of the design. This is a significant benefit for space-bound applications, where the total weight of the equipment is crucial. For example, a small flex-PCB that replaces multiple connectors can save considerable weight on a spacecraft.
Flex PCBs are also ideal for aerospace applications that must be able to withstand harsh environments and extreme conditions, including heat, vibrations, shocks, and radiation. Using a flex-PCB for these applications can significantly increase the lifespan of the device, as it can withstand much more environmental stress than a rigid-board counterpart.
Unlike rigid PCBs, which are prone to cracking or breaking under stress, flexible PCB boards can bend and conform to irregular shapes without compromising their integrity. This flexibility makes them ideal for applications that require bending or shaping, such as curved displays, flexible sensors, and rollable keyboards.
Considering all of the unique requirements of aerospace PCBs, it’s easy to see why designers choose to use flex-PCBs. However, the decision to move from a rigid-board to a flex-PCB should always be based on a cost/benefit analysis. If your design does not require the specific benefits of a flex-PCB, then a rigid or fully-flex PCB may be more cost-effective for your application.
