Bending Radius Affect Flex PCB Production
The bending radius is the minimum amount of curvature that the flex PCB can sustain before suffering damage to its copper. It is an important factor that must be considered during the design phase of a flex circuit and can significantly affect its performance and lifespan. The bending radius is determined by a number of factors, such as the type of materials used and how many layers are in the circuit. A flex circuit that is designed for dynamic use should have a larger bend radius than one that will only be used infrequently.
The thickness of the flex circuit is also an important factor. Thicker PCBs require a greater bending radius than thinner ones, but the exact size will depend on the materials and layers used in the circuit. For example, a stranded copper wire has a smaller bend radius than a solid copper conductor. The material used to make a flex pcb production also has an impact on the bending radius, as some types of materials are more malleable than others.
Another factor is the number of traces in the flex circuit. Multiple traces in close proximity to each other can put significant strain on the copper, which can cause it to crack during a bend. The best way to minimize this risk is by using a smaller trace width and a longer length, which will help spread out the stress over a wider area. It is also helpful to reduce the number of vias in the flex circuit and use a larger diameter for any that do exist.
How Does the Bending Radius Affect Flex PCB Production?
If the flex circuit is made from a multilayer board, the bending radius can be calculated by multiplying its thickness by a factor based on the number of layers and material type. This factor, called N, will determine the minimum bending radius for the circuit.
In addition, it is important to consider the number of flex cycles the circuit will experience. A flex circuit that will be subjected to frequent bending needs a larger bend radius to reduce stress and prolong its lifespan. The size of the bend radius is also dependent on the location and placement of the flex circuit. Plated through-holes and components should be avoided in the bend region as they can concentrate stress on the flex. Conductors should be routed perpendicular to the bend axis and staggered when possible to prevent I-beaming.
It is also important to understand whether the flex circuit will use panel plating or pad-only plating (button plating). Panel plating distributes copper across the entire surface of the board, while button plating deposits the copper only on the pads and vias. The former is more susceptible to cracking during a tight bend, while the latter offers better impedance control and etch yields in narrow traces. If your flex circuit requires a high number of bend cycles, it is best to choose the button-plated option. This will provide more protection for the copper and improve the circuit’s longevity.
