FAQs About Rigid Flex PCBs

The Printed Circuits team often receives inquiries regarding rigid flex printed circuit boards (PCBs). For your convenience, we assembled a list of the most frequently asked questions (FAQ) regarding rigid flex PCB uses, pricing factors, lead times, and more.

1. What is a rigid flex PCB?

Rigid flex PCBs merge elements of both rigid and flexible circuit boards into one composite design. In a typical rigid flex board design, the flexible circuit substrates are incorporated within the rigid circuit board materials. The flexible aspect of rigid flex PCBs allows them to be easily folded and bent to accommodate the surrounding space, while the rigidity provides a firm substrate for areas needing more mechanical support and component assembly.

2. What are the differences between rigid, flex, and rigid flex?

Rigid PCBs are stiff and unbending by design. While their low cost makes them attractive, the uses of rigid PCBs are limited due to their inflexible nature. Flexible PCBs, on the other hand, are more versatile due to their ability to flex and bend as needed to fit a designated system. Rigid flex PCBs are a hybrid design of rigid and flexible boards, allowing them to be sturdy and supportive in some areas and flexible in others. The design freedom, weight reduction, and spatial efficiency provided by rigid flex PCBs make them attractive for many applications. Check out our blog, “The Differences Between Rigid, Flex, and Rigid-Flex Printed Circuit Boards”for full details about each board type.

3. What are the advantages of a rigid flex PCB?

The durability and reliability of rigid flex PCBs means they can tolerate high levels of shock and vibration, making them well-suited for stressful environments and “never fail” electronics applications. Rigid flex PCBs are also built to withstand hundreds of thousands of flex cycles without failure. In terms of their compact and inclusive design, rigid flex PCBs enable a reduction in package weight and an increase in package density, all with much improved reliability. Furthermore, their increased circuit density allows for space economization and improved functionality.

4. When are rigid flex PCBs not an ideal fit?

Despite their many advantages, rigid flex PCBs are not always the best fit for every application. For example, they come at a higher price point and may not be the best option when low cost is a top priority. It is also important to consider that rigid flex PCBs tend to have longer manufacturing cycles and lower manufacturing yields relative to rigid and flex boards due to their design complexity, and the combination of dissimilar materials.

5. What should I keep in mind when creating my first rigid flex PCB?

With many customizable design factors available, designing a rigid flex PCB for the first time can be somewhat challenging. Being well informed about the many aspects that go into a circuit board’s design will help ensure its success in your downstream application. Transition points, for example, should be one of the most critical considerations for your design. This and other important points are covered in our “Rigid Flex PCB Application & Design” eBook, which we created to guide users through the design process – especially a first-time project.

6. What does the manufacturing process for a rigid flex PCB look like?

The first step involves building each of the subcomponents that will ultimately be combined to form the final product. The number of required subcomponents—which will vary depending on your design—including coverlayer along with the appropriate flexible and hardboard materials. Subcomponents are then assembled and laminated into the final product following a series of process flow steps, which are outlined in the chart below:

Click to enlarge
rigid flex PCB

7. How long are rigid flex PCB lead times, usually?

Rigid flex PCB lead times are generally about six to eight weeks, but there can be exceptions to that rule. For example, boards with filled-through vias will generally have two to three additional weeks added to the lead time. Operations performed by hand, such as the application of strain relief beading, will also add a few days to the expected lead time. Certain board designs require isolated plating, which will also increase lead times by a few days.

To get an estimate of typical lead times, please see the list below:

rigid flex PCB

8. Why are rigid flex PCBs so expensive?

One reason rigid flex boards tend to be more expensive than alternatives is the high cost of the raw materials used to build them. The largest cost driver is the no flow prepreg – essential to manufacturing rigid flex PCB’s. No flow prepreg is significantly more expensive than traditional hard board prepregs and is only available in two glass styles – 106 and 1080, which are both very thin. Another cost driver is the use of adhesive-less flex materials, which tend to be expensive but are strongly recommended for the most reliable rigid flex PCBs (see IPC 2223 4.2.4.1).

It is important to also consider the additional costs associated with traditional PCB solutions – rigid boards with connectors and flex cabling (additional assemblies required, cable and connector costs, etc.) to get a more comprehensive and accurate cost comparison.

9. What will a rigid flex PCB for my application cost me?

To give you an idea of what your rigid flex PCB design might cost, we have created this quick and simple cost approximation tool. Its purpose is to provide you with an estimate to help you decide if rigid flex pricing will fit your project’s budgetary objectives. For construction and design recommendations aimed at streamlining costs, please see our ValuBuild brochure.

10. What certifications are important for a rigid flex PCB?

The ISO 9001:2015 certification demonstrates a company’s ability to consistently provide services and products that satisfy quality goals and create an environment of continuous improvement. Another important certification is the difficult-to-obtain UL 94 V-0, which enables board constructions to be immediately certified at no cost to PWB designers or buyers. Furthermore, the MIL-PRF-31032 specification demonstrates a company’s ability to manufacture reliable products that consistently meet stringent military guidelines.

Printed Circuits has acquired each of these certifications and more, ensuring that our products consistently meet the highest quality standards laid out by the most demanding industries.

11. How do I do impedance control on a rigid flex circuit?

For valuable insights regarding impedance control for rigid flex PCBs, please see our Rigid Flex PCB Application & Design eBook. Roughly 40-50% of our boards are designed using impedance control to optimize performance and reliability.

Do you have a question that’s not answered here? Submit it here:

About Printed Circuits

Printed Circuits is an industry-leading manufacturer of custom rigid flex PCBs. By merging the most advantageous features of rigid and flex circuit boards, our rigid flex boards provide a thinner and highly versatile PCB solution that can be uniquely tailored to meet your project’s specific needs. We have earned a number of certifications that demonstrate our ability to meet even the most stringent manufacturing requirements.

Our rigid flex PCBs are manufactured using the most cutting-edge technology available to ensure maximum product yields, close attention to detail, and minimal production costs. With our wide-ranging expertise and advanced circuit board manufacturing equipment, we have the ability to manufacture custom rigid flex PCBs for myriad industries and applications. While our largest market is military electronics, we also have extensive experience providing rigid flex PCB solutions for medical electronics, aerospace, and industrial and commercial applications.

To learn more about our custom rigid flex PCB solutions, reach out to us today.