PCB Manufacturing

What is Semiflex PCB? Differences with Flexible PCB

Semiflex PCB

Are you looking for a semi flexible PCB solution for your project but do not wish to invest too much time and money needed for a flexible PCB? An FR4 semi-flex PCB may be the answer to your requirement. Explore the possibilities of FR4 semiflex PCB with Viasion and make the most out of your budget with high-efficiency, reliable, and durable PCB solutions custom-curated by our experts.

What are Semiflex PCBs?

Semiflex PCBs are PCBs that can bend only to a certain degree and at certain points as per their predefined requirement and design. In other words, the entire board of such PCBs is not bendable or flexible, rather, its structural integrity remains intact while being bendable at some points (usually one) for enhanced functionality and added benefits.

Semiflex PCBs prove to be an economical solution for applications that require the flexibility of the PCB only for installation purposes. This is because the FR4 materials used for fabricating semi rigid flex PCBs are quite cheaper than polyimide, the material used for fabricating flexible PCBs. To understand whether a semi FR4 flex PCB is suitable for your requirement or not, continue reading below.

When to Use a Semiflex PCB?

  • The bendability of the PCB is required only at the time of installation, repair, and maintenance.
  • To avoid the use of connectors and wire harnesses while connecting two circuit boards.
  • For static use only i.e. the bent area of the PCB is not expected to undergo any dynamic stress.

The Material used in Semiflex PCB

Semi Flexible PCB

The FR4 materials used in semiflex PCBs are a special type of FR4 material which more flexible. It is not as fragile of normal FR4 material, so it can be bent a few times at a certain angle. FR4 PCB materials are usually made of laminated fiberglass. FR in the term comes from one of its features, i.e. “flame resistance”.  However, the FR4 material used in semiflex PCB is a specialized FR4 material that is less fragile and more robust.

Note that while FR4 semiflex PCB materials are generally much cheaper than materials like polyimide, their costs may vary with their subclasses or quality. Likewise, their features like hardness, water absorption, flexural strength, and thermal conductivity may also vary while lying in an expected range.

The Benefits of Semiflex PCBs

Semiflex PCBs are widely used in electronic devices that need static bending usage. It is a much cheaper substitution for flex PCBs.  Semi flexible PCB offers many other advantages. Find below some of its top qualities.

  • Cost-effective and much cheaper than flex PCB
  • Excellent mechanical strength and dimensional stability
  • Good electrical insulation and chemical resistance
  • Less complicated manufacturing processes
  • Versatility: can be used for single-sided, double-sided, and multilayer PCBs
  • Chemically resistant and low water absorption
  • Highly durable and reliable

What are the Differences Between Semiflex PCBs and Flex PCBs?

Both flex and semiflex PCBs are bendable and allow PCB engineers to design the PCB in a more dynamic style. These are best suited for modern-day flexible applications or applications with smaller bodies, like wearables. While rigid PCBs offer very little scope for experimentation, the flexible ones open new doors of possibilities. However, flex and semiflex types are completely different from each other besides having the common property of bendability.

Semi Rigid Flex PCB

Different Bending Angle and Status:

Flexible PCBs or flex PCBs are fabricated using a flexible polymer film base which makes the entire circuit board flexible. In other words, the entire PCB can be manipulated without worrying about damage. On the other hand, semi-flex PCBs are bendable only at certain points that are predetermined as per the design and application requirements. Manipulating a semiflex PCB in other areas can cause breaking and damage.

Different Number of Times of Bending:

Another key difference between flexible and semiflex PCBs lies in the number of times they can be bent. That is, flexible PCBs can be bent as many times (infinite) as required, whereas, semiflex PCBs can only be bent a limited number of times. Trying to manipulate a FR4 flex PCB repetitively can lead to a crack or damage. Therefore, such PCBs are preferred only in cases where the bendability of the PCB is required for installation and future maintenance purposes only. Devices with dynamic applications whose PCB is expected to bend during usage call for a flexible PCB.

Cost Difference:

Flexible and semiflex PCBs also differ from each other in terms of their costs. Since the polymer film or the polyimide material is much costlier than FR4 materials, flexible PCBs are much more expensive than semiflex PCBs. Therefore, in cases where the application does not require much mobility frequently, FR4 materials are preferred. However, consider discussing with your PCB manufacturer before finalizing the right material for your PCB requirement.

Flexible PCB  Semi-flex PCB 
The entire circuit board is bendable, flexible, and movable. Only certain predetermined areas are bendable.
The board can be bent any number of times, suitable for repeated flexing. The bendable areas can only be bent a few times, beyond which the board may break.
Suitable for dynamic applications. Suitable for static use only.
Made with polymer film base. Made with FR4 materials generally.
Costlier than semiflex PCBs. Economical PCB solution.


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