Flexible PCB design guidelines differ dramatically from traditional rigid PCBs. We’ve discussed this in 5 must-knows for your first flex design. One of the most crucial differences? The bend radius. Rigid PCBs do not flex or bend, and do not require a bend radius. Flex PCBs, however, require very specific bend radius calculations.
Before beginning your design, identify the bending degree required, and whether your flex is a static (or bend-to-install) or dynamic (architecture allows for thousands of bends) board. Static boards, require a tighter bend radius than dynamic boards. Here are two strategies for increasing your bend radius.
Heat-Forming Flex PCBs
Heat-forming requires a steel jig, as it forces the board to lie a certain way. The steel jig is then inserted into an oven. One of the benefits of heat-forming is the tighter bend radius it provides. However, heat-forming is used primarily for ease-of-installation; tighter bend radius just happens to be one of the additional capabilities it provides.
Cutouts And Slots In The Bend Region
If there are no traces in the bend region, the bend radius can be minimized through the insertion of cutouts, or slots. Using cutouts will reduce the amount of material required to bend. Another option is removing sections of the flex where there is no circuitry, although this must be removed lengthwise and will require routing afterward.
Want to learn more about flexible PCBs? Download our Flex Design Guide!