A flex-rigid PCB contains both flexible and rigid board materials. In these components, the layers of flexible substrate remain attached to rigid boards by external or internal means. Flex-rigid PCBs provide more options to designs while eliminating the need for costly or unreliable connections between flexible and rigid substrates.
Designing a rigid-flex board, even for companies like PCB assembly services suppliers like www.fccems.com, requires paying particular attention to the smallest of details. It is the best way to ensure the integrity of the board and the success of all the subsequent manufactured boards.
Stack management
The best PCB assembly services suppliers prioritize stack management. It should be a precise template for the finished item. Designers should use the appropriate software program to create rigid-flex layouts that work. If there is a flaw in the rigid-flex stack-ups or if inefficiently managed, then you will have to incur delays.
You may also have to put up with performance-related issues. You can use ECAD and the tools that support board-specific stack-ups while designing rigid-flex boards. With region-specific stack-ups, you will have to add more changes to fine-tune the design of the boards. Board-specific tools let you alter the outline of the board easily when designing the stack-ups.
Ground-plane integrity
Are you going to ask the manufacturers to design dynamic-flex or flex-to-install variants? Dynamic-flex boards should be able to fold repeatedly whenever someone uses a device. On the other hand, flex-to-install ones should bend only when you place it inside the gadget while assembling it.
Manufacturers can fabricate flex-to-install boards faster than dynamic-flex versions because you will apply mechanical stress only during placement. Ground-plane and overall signal integrity are the key concerns with dynamic-flex products. Then again, you should emphasize on the reliability of the substrates and other materials used in manufacturing the component.
For instance, if you plan to use solid copper ground planes to route high-speed circuits in a dynamic-flex board, then the unbroken copper layers on the flexible components may crack or fail at any moment.
Bend management
Trace routing is just one of the concerns to worry about when you carry ground planes or power on the flexible zones of the boards. In situations such as these, surface-mounted pads and the through-holes also remain at risk in bends that fold repeatedly. That is why you must use additional coverlay for anchoring surface-mounted pads.
Furthermore, you should through-hole plating to increase the overall durability of the PCB. Experts suggest you refrain from designing rigid-flex boards with components or vias close to the bends. The constant mechanical stress can affect both the components and vias close to the foldable.
One last aspect
While designing the traces, you should route them perpendicularly to the bending areas. Such a routing configuration will reduce the stress on the traces in rigid-flex boards. Another trick for you to use is to offset the traces on double-sided rigid-flex circuits.
Once you stagger the traces on the top and bottom of a circuit, you will realize the board gets stronger and can withstand continuous bends with better consistency. You must avoid bending the traces at a 90-degree angle as it imparts more stress on those traces. Instead, you should design them to follow straight paths.