Minimum Bending Radius For Flex Circuit PCBs

Radius For Flex Circuit PCBs

Flex PCBs must be designed to withstand a wide range of mechanical stresses that may be applied to them. These stressors can include bending, abrasions and shock. One of the most important aspects that a designer must take into account is the minimum bending radius. This is a measurement of the maximum distance that the copper should bend before it is subjected to damaging forces.

It is recommended that the bending radius be at least ten times the thickness of the circuit board, although this is subject to change depending on the design. The bending radius is determined by the amount of pressure that will be applied during bending, and how much force is exerted on the edges of the curve.

When a flex or rigid-flex circuit pcb is bent, it creates compressive forces on the inside of the bend and tensile forces on the outside. This pressure can cause damage to the traces and copper connections in the circuit board. These types of stresses are why the minimum bending radius requirements were put in place. A flex PCB that is bent beyond its minimum bending radius may experience trace failures, component damage and other problems that require costly repairs.

Minimum Bending Radius For Flex Circuit PCBs

The minimum bending radius for a flex circuit PCB depends on a variety of factors, including the type of flex PCB and the material that it is made from. For example, thicker plates are stiffer and tend to have lower bending limits than thinner ones. Also, the type of copper used is an important factor. For example, thinner copper traces are more flexible than thicker traces. It is also a good idea to use an Un-bonded Air Gap construction for a multilayer flex PCB, as this can help increase the bending flexibility of the design.

It is also a good idea to stagger traces in a multi-layered flex PCB so that the conductors are not directly adjacent to each other, which can cause stress points during bending. This will help to reduce the likelihood of copper breakage, as well as I-beaming, which is caused when a flex circuit is bent multiple times in a row. In addition, it is important to avoid plated through-holes (PTH) in the area of the flex PCB that will be bent. Bending a PTH can cause the copper to break off from the base of the hole, which can be difficult and expensive to repair.

As the flex PCB industry evolves, designers must constantly be aware of how different materials and construction techniques impact the minimum bending radius requirements. Pushing flex and rigid-flex materials beyond their recommended capabilities will result in failures that can be very costly to fix. To avoid these issues, designers should work with their CMs to understand the limitations of the flex and rigid-flex materials they are using and to optimize designs for minimum bending requirements. This will help to ensure that the flex or rigid-flex PCB meets its design specifications and can be successfully deployed in harsh environments.

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