6 Layer Rigid Flex PCB: Everything You Should Know

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Oakley Mae

The 6 Layer rigid-flex PCB is one example of the remarkable advancements in circuit board design.

See, it combines ingenuity in materials, stackup, and construction.

As a result, these boards have improved functionality, mechanical support, and reliability, among other benefits.

This article discusses the 6 Layer rigid-flex PCB’s design construction, fabrication, benefits, and application. 

Table of Contents

What Is a 6-Layer Rigid Flex PCB?

The 6 Layer rigid-flex PCB is one interesting board. That’s primarily because it has the characteristics of a PCB and an FPC.

That means you can use it for different devices with special requirements.

A great example of such a device requires a board with both flexible and rigid areas. 

Undoubtedly, such a board can help save on devices’ internal space.

That way, it lowers the volume size of the devices and improves their performance. Further, it has six conductive copper outlines constructed using different methodologies, such as routing, punching, and V-cut. 

Engineers apply the 6 Layer rigid-flex PCB in a wide range of products in various industries.

These include the motor vehicle, telecom, and lighting industry. It’s no wonder their popularity has soared over the years. 

6 Layer Rigid Flex PCB Design Constructions

The basic process surrounding a rigid-flex PCB construction starts with polyimide dielectric film clad with rolled copper. 

Polyimide

(Caption: Polyimide) 

And this material is more flexible than your standard copper foil. 

  • First, the engineer drills the copper-cladding base material. Then, selective plating is applied to the plated holes to isolate the conducting layers. 
  • After that, an insulate flex stackup with Bondply, a polyamide film with adhesive on either side. 
  • Finally, the engineer extends the ribbon from the flex stackup area to a particular section located on the rigid PCB. 

Usually, most engineers are familiar with rigid PCB designs where even layer counts are a prerequisite.

But the opposite is true with an odd layer cont design. Still, although they’re not widely known, rigid PCBs with an odd layer count have their set of advantages. 

Interestingly, both of these PCBs (odd and even layer count designs) apply to both flex and rigid sections.

What’s more, they’re independent of one another. You could even opt to have an even layer on one side and an odd one on the other if the project allows it. 

Tips for 6-Layer Rigid Flex PCB Fabrication

The following are some of the do’s and don’ts on the fabrication of 6 Layer rigid-flex PCBs:

  • First, you should have a ground or power plane on a flex circuit to enhance or retain the PCB’s flexibility. And you can achieve that with either hatched polygons or copper pours
  • Second, it’s important to provide support for the copper. That way, you ensure that it does not detach from the substrate, which, unfortunately, 6 Layer rigid-flex boards tend to do. 
  • In addition, strictly adhere to the stated tolerance levels whenever possible. 
  • Also, don’t lay traces over each copper layer in the same direction. Instead, the best thing to do is stagger the traces. That way, you get an even tension distribution between the copper layers. 
  • Ensure that you maintain flex that’s bendable and foldable using the right kind of materials. 
  • Further, try to keep the circuits small. Because a smaller setup usually is better than a large circuit. 
  • Another thing to avoid is bending the flex circuit at its corners. If you need to, ensure you make a smooth curving or use some conical radius bends.    

Benefits of 6-Layer Rigid-Flex PCBs

The 6 Layer rigid-flex PCB provides users with various advantages for commercial, residential, or industrial electronics setups. These include:

Improved Functionality

With their 3D design and layers of flex, these boards provide increased flexibility.

They’re capable of fitting into any small device based on the specifications of the PCB.

Also, the fact that its corners are flexible means a flexible connection. Further, the rigid component provides the circuit board with mechanical support.

And this, combined with the added flexibility, means engineers can apply these boards to highly complex applications. 

Reduced Weight and Size

Several systems in rigid boards often take up more space and can be heavier.

But by combining flex and rigid boards, you can streamline the design, reducing weight and package size. 

Rigidity in Movement

Now designers employ different pieces of a rigid-flex PCB using solder flux.

And these remain static even in intense situations, such as when there are shocks or vibrations. 

These boards provide the ideal options for devices susceptible to excessive vibrations and movement. 

Better Reliability of Circuit

Now reduced board-to-board connectors and solder joints lead to reduced connection problems.

Further, a 6 Layer rigid-flex PCB comprises flexible layers attached to the rigid layer externally, internally, or both.

Also, it means fewer premature circuit failures, which is one of the main reasons why almost all advanced and sophisticated electronic applications employ rigid-flex PCBs. 

High-Density Applications

Usually, the rigid component of a rigid-flex circuit, the 6 Layer rigid flex included, gets used for high-density device environments.

Also, flex circuits allow for extremely narrow lines that give way to a high-density device population.

6 Layer Rigid Flex PCB Applications

Usually, rigid-flex PCBs get used in the manufacture of medical equipment.

Some examples include pacemakers, body-tracking tools, heart monitors, imaging devices, breathing machines, and wireless controllers.

Their low weight and space specifications allow designers to develop more reliable products.

Also, 6 Layer rigid-flex PCBs often get used in military weapons. After all, such tools need to be efficient and robust in performance.

Also, their ability to reduce the overall weight of ordinances makes these PCBs a highly sought-after commodity.   

Additionally, you’ll find the 6 Layer rigid-flex circuit board in consumer electronics like microwave ovens, calculators, and TV remote controls. 

Further, these circuit boards are crucial components in the telecoms industry.

So they’re applied in storage systems, relay stations, wireless systems, analog/digital broadcasting systems, and mobile communication systems. 

FAQs

What is a Rigid-Flex PCB?

A rigid-flex PCB combines board technologies of rigid and flex PCBs.

Thus, it consists of several layers of flexible circuit substrates attached to one or more rigid boards internally, externally, or both, based on the application’s design.

What are the types of Rigid-Flex PCBs?

Undoubtedly, there are several types of rigid-flex PCBs.

But the most commonly available and widely used ones are the single, double, and multi-layer rigid-flex circuit boards. 

What Is the Maximum Size of a Flex PCB?

The maximum dimensions of a flex PCB are approximately 450 mm (18 inches) by 610 mm (24 inches).

And a thickness of 0.3 to 0.45 oz per square foot. 

Conclusion

Without a doubt, PCBs have come a long way since their introduction in the early ‘90s.

It’s no wonder today; most manufacturers can produce PCBs in various specifications, such as 6 Layer rigid-flex PCBs.

We hope you now understand more about the 6 Layer rigid-flex circuit board.