Rigid Flex PCBs
Rigid flex is a hybrid of rigid or flexible PCBs that offers both the structural strength of a rigid board and dynamic adaptability of a flex circuit. It can be used in a wide range of electronic devices from medical implants and foldable wearables to robotic systems, automotive electronics, and aerospace applications.
Like rigid and flexible PCBs, a rigid flex board has a multilayer copper core that is etched, plated, and drilled. In addition, it contains a coverlay application and a solder mask layer. The coverlay protects the circuit from contaminants and facilitates automated assembly. However, unlike traditional PCBs, rigid flex can be manipulated and creased to change its shape. This flexibility makes rigid flex an ideal option for devices that need to fit into small spaces and must be capable of resisting extreme vibrations or temperature changes.
To make a rigid flex PCB, fabricators begin with either pre-laminated flex or unclad PI film. They then laminate the flex and plate up the initial copper layer using chemical or physical cladding methods. This one- or two-sided flex circuit is then drilled, plated, and etched as a single panel, much like a rigid PCB.
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How are rigid flex boards different from traditional rigid or flexible PCBs?
The flex section of a rigid-flex PCB is then inserted between the rigid sections. Depending on the design, the flex circuits may be embedded in one of the rigid sections or may be attached to both of them. The flex circuits are then routed to their respective lands on the rigid panels and the conductive patterns, pads, and through-holes are plated. The plated through holes are then mechanically drilled by a precision drilling system or by spraying an etch solution to expose the copper. The copper is then deposited through the plated through holes.
Rigid flex boards provide increased reliability by eliminating the need for connectors and by reducing the number of points of failure. In addition, their hybrid structure improves mechanical stability, limiting fatigue and cracking in harsh environments.
Many of the same manufacturing processes that are employed when producing rigid or flexible PCBs can be utilized with a rigid-flex circuit, minimizing production costs and lead times. However, the bending capabilities of a flex circuit require special consideration during the design process. Rigid-flex designs must be carefully analyzed and engineered to ensure that the flex section is not stressed beyond its limit, which can cause signal loss or mechanical failure.
In order to achieve the best results, rigid-flex PCBs should be designed by a team of engineers and designers who are experienced in both rigid and flexible circuit board fabrication. In addition, a thorough simulation and testing process should be performed to verify that the final rigid-flex design meets all of the required specifications. This requires close collaboration between the design team, fabricators, and assemblers to ensure that the final product is functional and reliable. For more information, contact a PCB manufacturer to learn how a rigid-flex printed circuit board can meet your specific design needs.