What Is Flex PCB Bend Radius?

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Have you ever looked at your smartwatch and wondered how it functions? New technologies are being developed daily, allowing engineers to downsize consumer electronics rapidly. People used to walk around with hand-held radio devices before the advent of cellphones, and then smartphones came and replaced them. The cornerstone of modern technology is how we have managed to create increasingly compact and lightweight electronics that function better than their traditional counterparts.

Printed circuit boards have made all this possible, allowing designers to make electrical connections in appliances. Technology would cease to function without circuit boards, so it doesn't take a genius to realize their worth.

Flex circuit boards are arguably one of the most game-changing types among the different types of printed circuit boards, owing to their numerous benefits. In this article, we will learn about flex circuit boards and the flex PCB bend radius!

What Are Flex Circuit Boards?

Flex circuit boards are flexible printed circuit boards, as the name suggests. You can twist, loop, bend, and manipulate their shape in any way to fit them inside electronic goods. Flexibility is both their defining and best characteristic. It affords them utility in a greater range of applications.

Consequently, flexible PCBs have become integral components in compact and lightweight electronics, such as wearable gadgets, laptops, and medical electronics. Their flexible nature allows the user to subject them to multiple looping or bending cycles, a fundamental reason for their use in movable mechanics designs.

Moreover, the flexibility of these printed circuit boards grants them unique advantages over their traditional rigid counterparts.

Benefits of Flex Circuit Boards

We can divide the benefits of flex circuit boards into three main categories: flexibility, lightweight, and connectivity.


Flexibility allows the designer more creative freedom over product design. These printed circuit boards can fit into tiny spaces, allowing users to create compact designs and downsize older electronics.


Flex PCBs are produced using extremely lightweight and thin sheets, which allow them to be flexible. The reduced weight is not just a fabrication requirement. Instead, it enables the production of products that are also lightweight, a basic need of modern electronics.

Furthermore, the lightweight flex PCBs can absorb more vibrational shocks, reduce wear and tear, and increase the long-term reliability of consumer electronics. They allow manufacturers to build complex yet durable products.


Flexible PCBs have a higher range of connectivity. A single flex PCB can connect multiple electrical components and connectors. Therefore, they're excellent for dynamic flex applications, which require printed circuit boards that can be bent or flexed for thousands of cycles. As a result, flex circuit boards are also used in foldable electronics.

Flex PCB Bend Radius

Even flexible printed circuit boards have a limit to how much stress they can withstand when flexed, twisted, or looped. The internal bend exerts compressive forces, and the external exerts tensile forces. These have threshold values, and remaining within them can prolong product life and ensure its continued functionality.

Consequently, this is where the flex PCB bend radius comes into play. It's a measuring metric used by designers to calculate whether a flex PCB will meet the bend requirements of a particular electronic device.

Furthermore, the flex PCB bend radius will allow a designer to calculate how much the flex PCB could be bent or distorted without damaging the board or reducing its lifespan. As a rule of thumb, remember that a smaller bend radius means more flexibility.

There are three design standards for flex PCBs according to the different bend requirements. The bend radius for these designs is calculated as a multiple of the final board thickness, and the bend capabilities are subsequently determined according to copper deformation.

  • Flex to Install
  • Dynamic Flex
  • One Time Crease

Flex to Install

The flex-to-install standard refers to flexible circuit boards bent into a specific shape to fit into a design. After achieving the desired shape, the flex PCB is not subjected to further stress or stress more significant than the bend radius.

For one to two layers, the flex PCB bend radius is six times (6x) the final layer thickness and twelve times (12x) for three or more layers.

Dynamic Flex

Dynamix flex applications utilize a design standard that involves repetitive distortion or movement of the flex PCB. Limiting the dynamic flex design to one or two layers is preferable to allow for maximum flexibility and a low flex PCB bend radius.

Furthermore, the copper can rest along the bend radius's neutral axis in dynamic flex applications. The neutral axis neither experiences compressive nor tensile forces, protecting the copper from deformation. The flex PCB bend radius in dynamic flex is a hundred times (100x) the final layer thickness. Therefore, the dynamic flex standard is typically utilized in applications involving moving or mechanical parts and foldable electronics.

One Time Crease

A flex PCB based on the One Time Crease standard is folded to form a crease and achieve a zero bend radius. After the crease has been created, the circuit board fits inside the final assembly. It is not required to move or unfold after the final installation. Its only requirement is to maintain its conformation.

As a result, the bend radius becomes irrelevant in the third design standard as the printed circuit boards are not required to change their conformation. However, it is essential to understand that the flex materials and copper weight must be incredibly thin to avoid reliability concerns regarding the design's structural integrity.

Additionally, the layers are kept to a minimum, and pressure-sensitive adhesives are used to hold the crease together, while the copper weights are placed along the neutral axis to prevent deformation.


The flex PCB bend radius is a crucial metric in understanding design capabilities and the PCB fabrication process. Different flexible circuit boards utilize varying layers, affecting the flex PCB bend radius. You can learn how to calculate the bend radius here.

However, we suggest referring to Hemeixin Electronics, the world's leading manufacturer of custom flex circuit boards. You can visit Our website and contact an agent for all your flex PCB needs. Why design them yourself when experts can do it for you?

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