Why Do Flexible PCB Need Stiffeners?

Flexible Printed Circuit Boards are made of thin dielectric substrates and highly ductile metal foils.Flexible PCB can be bent or folded and used in static and dynamic applications.

Flexible Circuit Board Reinforcement

Demand for flexible PCBs is growing in all business sectors, with particular demand from the medical, military, and industrial markets. Because the volumes of these parts are typically small, pcbandassembly can handle many high-mix, low-volume flexible PCB orders that meet both technical and volume requirements.

What Is a Flexible PCB?

Flexible printed circuit boards (also known as Flex PCBs) get their name from their ability to allow the circuit to be designed to fit the electronic device or product. Flex boards feature distinctly patterned printed circuits and ductile base materials, which can highlight component arrangements.
When we discuss flexible PCBs, we will consider the connection with other devices. At this time, we will consider using stiffeners in Flexible PCB design.
Flexible PCB stiffener materials commonly used: Fr4, PI, and aluminum.

When Using Reinforcement

Stiffeners can be used to reinforce areas where components will be assembled but not where the board will flex. Your board needs stiffeners on both sides where it flexes. You may need two laminates. Also, stiffeners require their prepreg lamination cycle, and some stiffener materials require additional lamination cycles. They add thickness to the board and affect cost and manufacturing time. However, there are some situations where stiffeners are necessary.
Pure-flex PCBs can accommodate fewer components than rigid-flex parts. The rigid portion of a rigid-flex assembly can also be as complex as a traditional rigid circuit board. Stiffeners are sometimes laminated simultaneously with the covering.

Reinforcement Materials for Flexible PCB

Stiffeners are made of FR-4 or Kapton. Using Kapton when the end of a flex line must be lengthened and inserted into a ZIF connector. However, using Kapton requires a alone lamination cycle. FR-4 stiffeners can be completed in the same lamination cycle.
Use stiffeners for routing and fixing for flexible PCBs.
When routing and securing the array, the same material as the stiffener will extend into the array. It makes the array harden.

Flexible PCB Stiffeners Need to Be Used in the Following Situations:

• Components located in active or dynamic bending areas near
• The component’s size and weight puts stress on flexibility
• A large number of SMT pads makes planarity critical
• Connectors that repeat insertion or assembly require stiffeners or some parts that help relieve stress on the backing plate.

Reinforcement Is Not Required in the Following Cases:

• Smaller “static” components do not put much stress on the flexibility of the PCB. There are no components in the flex area.
• Flexible PCB Design Techniques

Extend

1. What Are the Advantages of Using Flex Cables Compared to Cables?

Pcbandassembly SMT assembly: Flex PCB provides several advantages for cables.
We discussed the advantages and disadvantages of both. The higher upfront cost of Flex PCB will hugely reduce costs in the long run. Cables can take weeks to produce, while flexible PCBs can be completed in days. In short, using a flex circuit board can eliminate or completely reduce cable costs, reduce assembly time, and produce a lighter final product.

2. What Are the Preferred Hole and Pad Aizes for Flexible PCBs?

Like Kapton, flex materials do not drill as well as conventional materials. For minimum size, ten mils and above are preferred only in flex. Rigid-flex PCB specifications are similar to rigid board specifications. Pad size and plating process for flex are only for barrel (hole wall). The flex holes are not plated on the surface due to the need to bend and keep the electrodeposited copper away from the surface.

3. Elastic Prepreg

No-flow prepreg is the preferred bonding material for joining flexible and rigid materials. It is most commonly standard FR-4 or polyimide.

4. What Are Some Alternative Materials to Prepare for Joining Flexible and Rigid Materials?

No flow prepreg is the preferred bonding material. Available in standard FR-4 or polyimide.

5. What Does a Real Stack Look Like?

The planar layers of the flexible layer are the same as those of the rigid board.