What Is a Rigid-Flex Printed Circuit Board?

Rigid-Flex Printed Circuit Board

A rigid-flex printed circuit board is a type of PCB that combines both the physical constraints of a rigid PCB with the flexibility of a flex PCB. These boards are ideal for applications that require a high level of reliability and durability, such as medical imaging equipment, military missile guidance systems, video cameras, wearable electronics, or vehicle infotainment systems. Rigid-flex circuits can also help lower costs by reducing assembly steps and limiting component placement.

The design of a rigid-flex PCB requires careful consideration of several electrical and mechanical specifications. The choice of material for both rigid and flexible sections must be made with care, as different materials have varying thermal expansion coefficients that can lead to reliability issues in the transition zone. The selection of the correct bend radius for the flexible section is also important, as an overly small radius can cause signal integrity and electromagnetic interference (EMI) problems. Additionally, the placement of connectors to handle the transition between the rigid and flexible sections must be carefully planned, as poor connection locations can cause stress on the connections and signal quality.

Another factor that makes rigid-flex printed circuit board a desirable solution is that they can reduce overall assembly costs by eliminating the need for multiple cable assemblies and connecting wires. This reduces the number of assembly steps, which in turn cuts manufacturing costs. Additionally, using a single production line to make both rigid and flexible circuits can save money by eliminating the need for multiple changeovers between production runs.

What Is a Rigid-Flex Printed Circuit Board?

Rigid-flex circuits are also designed with protective coatings that help them resist the various chemicals, oils, hydrocarbon solutions, dust, and other contaminants commonly found in industrial environments. They can also be coated to improve their resistance to temperature fluctuations and increase their ability to withstand mechanical stress. The use of these coatings can also reduce the time needed to make repairs, which is another major benefit of using rigid-flex circuits.

In addition to the protective coatings, rigid-flex circuits are often manufactured with epoxy adhesives that provide a strong bond between the substrate and conductor layers. These adhesives are typically chosen because they can withstand elevated/fluctuated temperatures and are highly durable. They are also often formulated to increase adhesion, enhance strength, and decrease oxidation.

Rigid flex PCBs can be made with copper, gold, or silver conductor layers, and they are available in single-sided, double-sided, or multilayer constructions. They can also include shields, stiffeners, and plated through holes. Some rigid-flex PCBs are also coated with a protective film, which increases their durability and reduces the risk of accidental damage during handling or installation.

Creating a new rigid-flex PCB requires specialized design tools that are compatible with both the structural and electrical requirements of this type of circuit board. The best way to achieve this is by using a unified electronic design platform that can accommodate all of the tools you need for your project. Altium Designer has all of the rigid-flex and flex PCB layout tools you need in a single, integrated software package that can be used to create your entire product design from start to finish.