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Circuit Construction Guidelines

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).


Staggered Conductors
Preferred Construction
I Beam Construction
Not Recommended

Note: Circuits run perpendicular to the fold area to help reduce breaking during folding.

Bend Radius for flex to install should be approximately 10 times the
material thickness and at least .050” away from the plated through hole.

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.
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.