Definition

Bend radius is the minimum radius a flex circuit can bend without damage. Rule of thumb: minimum bend radius equals 10x material thickness for dynamic flexing (repeated bending), 6x for static flex (bend once and stay). Tighter bends stress copper, causing cracks and failures. Single-layer flex bends tighter than multilayer. Placing copper at the neutral bend axis reduces stress. Stiffeners prevent bending in component areas. I-beam (hatched) copper patterns improve flex life. For rigid-flex, transition zones between rigid and flex sections need careful design to avoid stress concentration.