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Radiused Traces help to alleviate breaking during folding and bending. (Refer to diagram above for example).
I-Beam vs. Staggered Conductors:
I-Beam constructions occur where the conductors on both layers lie directly on top of each other, increase the stiffness of the circuit through fold areas. A better alternative is to stagger conductors, alternating their location to retain the maximum flexibility of the circuit (see below). |
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Staggered Conductors
Preferred Construction |
I Beam Construction
Not Recommended |
Note: Circuits run perpendicular to the fold area to help reduce breaking during folding.
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Bend Radius for flex to install should be approximately 10 times the
material thickness and at least .050” away from the plated through hole.
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Selective Thru Hole Pad Plating / button plate is a process that allows for the through holes to maintain their connection while the traces are not plated, allowing the circuit to have increased flexibility. |
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Flexibility and Forming
When designing for dynamic or continuous flexibility, the following rules must be considered:
- Circuitry should be maintained on one conductive layer only.
- All circuitry should be routed perpendicular to the bend, across the flex area.
- Conductors should be evenly spaced, uniform in width and maximized across the bend area.
- The copper layer should be maintained in the neutral axis of the bend.
- Coverlayer openings or windows should be kept a minimum of .100” away from the start of
a bend, and if possible a strain relief should be added to dictate the start of the bend.
- Copper Grain direction is critical when designing for dynamic circuit applications.
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