Flexible PCBs for Military
Printed circuit boards (PCBs) are laminated structures of conductive insulating layers. They host various electronic components in designated areas on their outer layers, and connect them via traces or planes to ensure reliable electrical connections between them. They’re used in almost every device and electronic piece of equipment we use, from computers to smartphones. They’re also critical for specialized applications like formfitting medical patches and diagnostic tools.
Military PCBs must be able to withstand harsh conditions and extreme temperatures, such as those experienced by military equipment and vehicles. These boards must also meet stringent sanitation requirements and withstand vibration, shock, and acceleration. They must also be able to resist heat-induced oxidation and efficiently dissipate thermal energy. MV flex circuits are specifically designed to address these challenges, making them an excellent choice for military applications.
Rigid flexible pcb board are typically constructed with high-quality materials and undergo rigorous MIL-SPEC environmental testing including vibration, mechanical shock, salt fog, temperature cycling, and more. These tests are performed to determine the quality of the material and workmanship as well as the durability of the board. Rigid flex PCBs can be found in a variety of military applications, including missile and munitions guidance systems, radars, soldier-worn systems, displays, communications, and drone/UAS control.
Flexible PCBs for Military Applications
Flex PCBs can be constructed with one or more conductor layers. The number of layers depends on the size and complexity of the circuit. They can be fabricated with or without plated through holes, although the latter is more common. They can also be single-sided or double-sided, with plated through hole access on either side.
To maintain flexibility, flex circuits must be carefully designed with special attention to routing. Traces must be routed away from bend areas, and drilled holes should avoid passing through these zones in order to protect them from damage. It’s also important to avoid overlapping layers when routing traces near a bend zone. It’s also recommended to keep flex circuit layer counts as low as possible and to stagger layers. Additionally, the bending of a flex circuit can cause stress points if the layers are too rigid. To reduce these stress points, it’s a good idea to transition from wide traces to narrow ones in a gradual fashion instead of an abrupt change.
Flexible PCBs also offer cost-effective solutions for certain applications by simplifying assembly processes and reducing the number of components required. The elimination of connectors and cables reduces material costs and assembly time, resulting in overall cost savings for manufacturers. Additionally, the streamlined design of flexible PCBs can lead to fewer points of failure, reducing maintenance and repair costs over the lifespan of the product.
To improve flexing endurance, a number of design features should be employed. These include avoiding 90deg traces, minimizing rigid-to-flex transitions, using wide pad/via annular rings, strategic placement of stiffeners and components, and the use of rolled annealed copper. These design factors can dramatically improve dynamic flexing endurance. The ultimate goal is to ensure that the flex circuit is able to withstand repeated bending cycles without deteriorating.