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What is Rigid Flex PCB? All You Need to Know

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Rigid flex PCB
Rigid flex PCB
Resource: https://www.sciencedirect.com

PCB requirements vary widely. In some applications, a board that is bendable in some areas and rigid in others is needed, and the rigid flex PCB is designed to meet this demand. This type of board offers the advantages of both rigid and flexible boards in one package, which can be an advantage in many different situations. The rigid flex PCB technology, together with its numerous benefits, is discussed at length in this article.

What is Rigid Flex PCB?

A rigid flex PCB is a hybrid — or combination — of rigid and flexible PCB types. It has a circuit layer that does not bend (the so-called “rigid” part) as well as layers of flexible circuits that can be bent and folded.

This rigid flex PCB design allows the board to be used in electrical or electronic devices that require a circuit board to bend or fold at certain points. These could be medical implants and consumer electronics or motor control devices and robotics.

The rigid flex PCB design can vary in terms of layers and configurations. For example, some boards may have one flexible layer while others employ multiple flexible layers with several rigid substrates.

Note that the rigid section is generally multi-layered, since it usually comprises the flexible circuit board embedded in rigid PCB layers. The number of layers and sections in a rigid flex PCB stackup then depends on the application requirements.

Rigid flex PCB stackup
Rigid flex PCB stackup
Resource: https://forum.kicad.info

Rigid Flex Technology

The rigid flex PCB technology has its origin in the military, where space savings and reliability were a priority. This was way back in the 1980s. Today, the rigid flex PCB market covers many sectors, from consumer electronic products to medical equipment. In order to understand how rigid flex circuits are used, let’s first see what they are.

What are Rigid Flex Circuits?

The rigid flex PCB circuit is a sandwich-like combination of rigid boards and flexible circuits which are interconnected, allowing for flexible designs that reduce board size and simplify assembly. The design can be tailored to fit the exact shape of a device.

Rigid flex boards can also be used in more complex applications where multiple rigid and flexible layers are combined to create an array of functionalities. The rigid portion of the PCB provides strength, mounting points, and other structural benefits, such as ability to bend in three-dimensional spaces.

Rigid Flex PCB Stack Up

The rigid flex PCB stackup is essentially a flexible circuit board that has been sandwiched between layers of rigid PCB material to make it stiff. While they are generally thin, the rigid flex PCB layer arrangement is based on the board’s specific application.

For example, a rigid part may be constructed with one or more layers of substrate material, which are then laminated with a layer (or layers) of copper traces and bonded to a flexing layer. The rigid flex PCB stackup also includes other elements such as vias, adhesives, and cover coat or cover layer.

Rigid Flex PCB Materials

Rigid flex PCB materials include those that make rigid PCBs and materials for flexible PCBs. The rigid part of the board is typically constructed from materials like FR4, or glass fibers reinforced with epoxy, which is known for its durability and strength.

For the flexible part of the board, polyimide is the most common material, mostly due to its good flexibility properties and better thermal performance. Other materials may also be used depending on the board’s specified application.

For the traces, copper is the most used rigid flex PCB material, both in the flexible and rigid parts. The copper traces in the flexible part must bend without issues, and rolled annealed copper is often used.

Rigid flex PCB flexibility
Rigid flex PCB advantages include flexibility to fit usage needs
Resource: https://www.edn.com

Advantages of Rigid Flex PCBs

Rigid flex circuit boards are an incredibly useful and used in many electronic products, from medical implants and wearable electronics to industrial robotics and motor control systems. In these many applications, they offer several benefits. The main advantages of rigid flex PCB types are:

Space savings – The ability to bend or fold in certain areas allows rigid flex circuit boards to be compressed into a much smaller size than rigid boards, which creates more space for components and other features in an electrical device.

Reduced Weight – Since rigid flex PCB boards are much smaller than solid boards, they also weigh less. This reduces the overall weight of a device, which is beneficial for applications like medical implants and wearable electronics.

Simpler assembly– Rigid flex boards are easy to assemble, since they use fewer components. They also require simpler installation steps, given that you do not need many connectors or cabling to link circuits.

Increased Reliability –The fact that you do not need many cables or connectors (and fewer solder joints) when using rigid flex PCBs increases the overall reliability of an electrical device.

Overall, the rigid flex PCB technology is a great solution for many types of electronics that require the board to bend or fold in certain areas while still providing strength and reliability — or where resistance to shock and vibration is an advantage.

Rigid flex applications in mobile technology
Rigid flex applications in mobile technology
https://www.edn.com/flex-circuits-innovations-and-processes

Rigid Flex PCB Applications

Rigid flex PCB applications cut across many industries, where they offer the best of both worlds – the strength and durability of rigid PCBs, combined with the flexibility and space-saving features of flexible ones. Common uses of rigid flex PCBs include those listed below.

Automotive and Industrial Electronics – one of the most popular rigid flex PCB applications is in the automotive and industrial sectors, where they provide robust and reliable performance for demanding applications. Examples include actuator in industrial systems and robotics.

Medical devices – Rigid flex PCBs have been successfully used in medical implants that require electrical connections to power different functions. Their flexibility and reliability make them ideal for this type of use.

Wearable Electronics – In wearable electronics, rigid flex PCBs provide the best of both worlds – strength to support components and flexibility to fit into different shapes or sizes. Examples include fitness trackers, smart watches, and other devices that need flexible circuitry.

Military Electronics – Rigid flex PCBs have been widely used in military electronics, from aircraft avionics to communications systems. Their ability to remain rigid where need and bend where necessary gives them an advantage over either rigid or flex PCBS.

Rigid Flex PCB Cost

The cost of rigid flex PCB depends on various factors: the materials used, the stackup type, and size. Generally, they tend to be more expensive than rigid PCBs owing to their design requirements.

However, due to their ability to use fewer or components and the reduced need for connectors, these PCB types can end up offering cost savings. For an accurate estimation of the rigid flex PCB cost it’s we recommend discussing your specific requirements with a PCB manufacturer.

Do you need rigid flex PCB manufactured? We are the PCB experts! Get in touch with us today to get a free rigid flex PCB quote.

Conclusion

A rigid flex PCB is an excellent solution for applications that require flexible electronics in specific areas, but without sacrificing the strength of rigid boards in the rest of the circuit board. They offer many advantages over standard rigid or flex PCBs, such as cost and space savings as well as reduced weight and increase reliability.

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