flexibility of a rigid flex board
Rigid flex boards are a unique type of PCB that offers rigidity and flexibility in the same device. They are often made of flexible polyimide materials that can bend and twist without compromising electrical performance. They are commonly found in devices like laptop computers and smartphones and are a valuable solution for projects with limited space or for applications that require a more compact form factor. Rigid flex PCBs are also often chosen due to their durability and longevity.
To ensure the flexible design of your rigid flex circuit board, there are several important factors to consider during the engineering and manufacturing stages. Proper planning, careful construction and materials selection, and working with an experienced electronic contract manufacturer are all essential to ensuring your rigid flex board meets all of your specifications and bend requirements.
The conductive paths in your rigid flex board must be placed carefully to reduce mechanical stress and the potential for copper traces to fracture. This is especially true when bending the board. The position of traces along the bend line and the corresponding bending radius can significantly increase or decrease the risk of failure. For this reason, it is best to use curved traces and gentle bends whenever possible.
How do you ensure the flexibility of a rigid flex board?
During the engineering phase of your rigid-flex PCB, you should also pay close attention to the position of vias. If you plan on using vias in your flex area, it is recommended that you use “rooms” to define regions where you know there will be no bends and then use the PCB editor’s design rules to only allow via placement in those stationary areas. This can help to prevent any confusion when designing the rigid-flex section of your PCB.
It is also important to minimize the number of through-hole pads in your flex area. This can be accomplished by using anchoring stubs and reducing the coverlay access openings. In addition, SMT component pads should be positioned in such a way that they are not exposed to the flex circuit and have a dedicated solder fillet to avoid bridging.
For high-current traces running parallel to the flex area, it is recommended that they be kept a minimum of 0.125 inches (12mm) away from the flex area to reduce the possibility of delamination or other damage during the bending and operating temperature variations. It is also advised that you route these traces on the opposite side of the PCB from the flex area.
It is also a good idea to keep the thickness of your rigid-flex PCB consistent throughout the entire board. Keeping the thickness consistent will help to reduce mechanical stress and prevent damage from handling and assembly processes. It is also a good idea to incorporate prototyping into your production process to catch any flaws in your design, as well as to perform rigorous testing to ensure that the rigid-flex PCB functions as intended. This will help to improve quality and reliability while minimizing cost through optimized design, reduced assembly time, and less component count.