The Importance of Rigid-Flex PCB Design Guidelines

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The rise of intelligent and robust electronic devices has brought an evolution to the use of PCB. Modern-age PCBs are more efficient and easy to use than conventional ones. Electronic engineers opt for rigid-flex PCB boards to complete the device circuits. Despite the ease of installing them, you must follow the proper design guidelines to use rigid-flex circuit boards.

To understand the importance of following the design guidelines in completing a circuit, let us first look at the nature of rigid-flex.

rigid-flex pcb stackup

How Is Rigid-Flex PCB Different from Conventional PCB?

They have a flexible structure, suitable for compact and sensitive electronic devices. Engineers use hardboard and flexible circuits to build rigid-flex circuit boards. Although the manufacturing process is similar to traditional PCB, rigid-flex comes with an adjustable circuit assembly that joins with the hardboard.

 

Engineers use board fabricators to create holes in the rigid body to attach the two parts if you wonder how flexible circuitry joins with a rigid hardboard. Traditional circuit boards are suitable for complex electronic devices with more circuit space. However, flexible circuits are ideal for smaller devices with limited space to enclose circuits.

Is Rigid-Flex Circuit Durable?

Rigid-flex circuit boards may consist of many layers of flexible circuitry depending on the type of device. You can twist and fold the layers without worrying about circuit malfunction or component damage. Such circuit boards are also an excellent fit for continuously flexing applications.

 

If you assemble and install the rigid-flexible circuit board following the proper design guidelines, your circuit can withstand thousands of layer cycles without compromising on its functionality.

Why Is it Important to Follow Design Guidelines?

The competition of compact devices in the market has increased the demand for rigid-flex circuits. These circuit boards are best-suitable for sensitive devices with shock-resistant properties. Using a rigid-flex board allows you to eliminate circuit damage problems in devices.

 

To ensure you design your rigid-flex correctly, it is essential to follow the design guidelines to avoid errors.

Placing the Plated Holes Correctly

The most crucial factor is correctly attaching the rigid part to the flexible circuit. When designing your rigid-flex board, you may need to avoid creating holes on bending sections. Many circuit designers overlook this factor and regret it later. Plated holes on turning circuit lines can disrupt the overall structure of the board.

 

You may need to aim for sections with minimum flexibility to avoid bending to avoid such problems. You can place pads and vias on the plated holes and connect the circuit layers. Using a teardrop can help you refine the joints by cleaning the edges.

Placing the Traces Correctly

Another critical factor that can save you from uncalled-for hassle is the positioning of traces. When you design your rigid-flex circuit board, you may need to analyze the routing across the circuitry. Since flexible parts of the circuit are prone to bending, you must use the traces correctly to avoid malfunctions.

 

When routing the traces on the bending sections, you may place them as perpendiculars. The perpendicular lining provides an increased mechanical sturdiness to the circuit board.

 

If you use a double-layer design, placing the traces in an alternative pattern (top and bottom) can work out better. You can also consult with one of the field experts to learn about the correct positioning of traces.

 

Regardless of the circuit design, you may avoid placing the traces on the corners. To change the route, you can opt for softer angles, giving the traces a curved path on the circuit board.

Placing the Ground Plane Correctly

The ground plane on a PCB acts as the base of the circuitry. It has a metal formation with varying sizes depending on the type of circuit. Any circuit board's ground plane supports voltage return, signal return, and reducing interference. Placing it correctly is crucial for smooth functioning. 

 

Placing the ground plane as a solid structure may lead to increased stress on the plane. The solid formation also decreases the flexibility of the circuit layers. On the other hand, using a cross-hatched structure can save you from these complications.

 

The cross-hatched ground plane allows ample space for flex cycles. You can install it on devices with maximum flexibility. Moreover, the path of voltage flow remains clear of interferences.

Core Benefits of Rigid-Flex PCB Design

Let's look at some of the core advantages of its design.

Mechanically Stable Circuits

The rigid-flex circuits are mechanically stable. The flexible layers of circuitry can undergo thousands of cycles in devices with limited circuit space. You can opt for multiple ways to install them without damaging the traces on the board.

Smooth Voltage Flow

The flexible structure of rigid-flex boards provides a smooth path for voltage and signal flow across the circuitry. These boards have fewer connectors, minimizing the chances of voltage cuts. Additionally, you can easily connect multiple components without major modifications to the circuit.

Dynamic Properties

Rigid-flex has an advantage of dynamism over traditional types of circuit boards. You can turn them, fold them, and enclose them in sections with space constraints. When designing your flexible PCB, you can opt for cross-hatched ground plane structure for improved adjustability.

Reduced Costs

One of the many advantages it is its reduced costs. Traditional circuit boards consist of several connectors and components that cost more. Moreover, such parts are often at risk of receiving damage. You may need to spend more on the maintenance side. While this may be correct, rigid-flex circuits can save you from added costs.

Shock Resistant Properties

Compact devices are more likely to slip from the hands and fall. It increases the chances of damaging the circuit board. However, with rigid-flex panels, you can let go of such worries. These circuits are shock-resistant and vibration-resistant, making them more sustainable than traditional circuits.

Wrapping Up

Rigid-flex PCB design has made it super easy to build smart devices. While traditional circuits come with many limitations, these circuit boards provide you with more freedom with reduced costs. If you follow the design guidelines mentioned earlier, you can build some of the most efficient electronic devices of the modern age.

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