Rigid-Flex PCB Design Guidelines

The evolution of electronic devices makes it easy to ignore or overlook the foundation upon which they are built: PCB, also known as printed circuit boards. Due to advances in materials and computerization, modern electronics have evolved from printed circuit boards (PCBs) to rigid-flex hybrid and multilayered boards.

Flexible layers are inserted into the rigid structure to balance the complexities and dependability of hardboard circuits. These boards are smaller, thinner, and more flexible than traditional circuit boards, enabling them to be employed in irregularly shaped or exceptionally compact devices. As a result, the development of printed circuit boards is expected to continue in the following years, with the boards becoming smaller and more complicated as technology advances.

Rigid-Flex PCB Design Guidelines

Rigid-flex printed circuit boards (PCBs) have recently received significant attention, owing to the increasing need for more compact, shock-resistant, and robust electronics. The rigid-flex structure doesn't require connectors or joining cables because the complete design is built on a single PCB.

While rigid-flexible circuit boards have several advantages, they also come with some obstacles for PCB designers. It is not only necessary for designers to deal with the electrical elements of a design, but they must also take into consideration the mechanical dynamics of the printed circuit board (PCB). If you happen to be working on a rigid-flex PCB board, the design guidelines provided below will help you avoid making costly blunders.

Consider the Rigid flex pcb Layer Count

Rigid-flex PCBs are constructed from layers of flexible and stiff PCB material that are alternated. Prepare for the transition by determining how many layers you will need for your intended usage as you are ready to make the switch. After that, check with your original equipment manufacturer (OEM) to confirm that it can meet those specifications.

Employ a Cross-Hatched Ground Plane

The ground plane will be subjected to a great deal of stress if formed from solid copper. This will reduce the ground plane's ability to bend. Instead, on the flex region of the PCB, a cross-hatched ground plane should be used.

Reduce the Amount of Heat Dissipated

Heat is dissipated by electrical equipment when current runs through them. Factors like device characteristics, power consumption, and PCB design influence the amount of heat generated. As the device's temperature rises, it will affect its functioning and may even cause damage. Reduce the quantity of heat that is dissipated by taking the necessary precautions. The PCB in your device should allow for better heat dissipation. This may be accomplished by adhering to rigid-flex PCB design principles and standards.

Take Time to Find the Best Material Layup

When it comes to rigid-flex boards, the material layup is critical, therefore; close collaboration with your fabricator is required to achieve the best layup, which includes considerations such as the UL flammability rating, appropriate materials, minimum bend radii, RoHS certification, Impedance control, mechanical considerations, and lead-free assembly compatibility.

Material layup significantly influences the final product's cost, performance, and manufacturability. When you've created a good mock-up, have a designer conduct the appropriate calculations, which the fabricator should validate before moving further.

It is best to utilize boards with various layers on them. For example, one with 20 layers and another with 12 layers. However, it is critical that they have a comparable layup, have a similar thickness, and adhere to the PCB design criteria for flex-rigid circuits. This will aid in the reduction of manufacturing concerns that might cause projects to be derailed.

Avoid Plated Through Holes on the Bending Areas

Areas along the bending line will experience mechanical stress, which may cause the structure of the plated holes to become compromised. Therefore, the placement of pads and vias on the bending region of a PCB's flex section should be avoided at all costs. However, using pads and vias in places not exposed to bending is possible, but it is not advised. In such cases, anchors should be used to reinforce the plated holes. A teardrop connector may also link the trace to the plated hole to strengthen joints. It is also recommended to utilize larger pads and vias wherever possible.

Pay Close Attention to the Routing Throughout the Bending Area

It is essential to maintain straight, perpendicular lines while tracing over the bending line and employ narrower traces uniformly distributed over the flexible region. A double-layer design should have traces routed alternately on the top and bottom layers and the middle layer. Moreover, avoid making any sharp turns with the traces on the bending region to prevent bending. The inclusion of dummy traces may aid in the improvement of mechanical sturdiness, which helps to prevent the traces from breaking. If the traces on a flex PCB shift direction, use curves (45° or 90°).

The Final Cut

For those who have spent their whole lives designing traditional printed circuit boards, developing a rigid-flex circuit board may seem like a strange concept. As the name indicates, a rigid-flex PCB is a printed circuit board that incorporates both hardboard and a flexible PCB into a single piece. It goes without saying that using design software that supports rigid-flex PCB design standards will aid in the creation of a prototype that is free of blunders.

Best Rigid-Flex PCB Manufacturer – HemeixinPCB

Ready to turn your concepts into reality? Join hands with a reliable rigid-flex circuit manufacturer like HemeixinPCB. Thanks to our rigid-flex PCB fabrication, the circuit boards may be made in various forms, and thickness can be customized according to your needs. This means that the circuit board's versatility is not limited to its physical features but includes many design options. In contrast to designing a product around your circuit board, we enable you to design your rigid-flex PCB around YOUR product, ultimately reducing space and size concerns.

Consider us to be your first choice for board makers. Visit our website for more information or drop us an email at This email address is being protected from spambots. You need JavaScript enabled to view it.

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