Medical devices
Portable instrument: rigid-flex replacing a cable harness
Rigid-flex · static bend · polyimide coverlay
A portable instrument team needed to remove a failure-prone cable interconnect between a display subassembly and the main controller.
Challenge
- Mechanical drawings showed a fold-to-install bend but lacked cycle count, radius, and stiffener edge details.
- Early layout placed vias too close to the flex transition—a classic crack initiator under handling.
- Assembly needed a flat, stiffened region for SMT while preserving the flexible arm for final fold.
Approach
- Intake clarified static (flex-to-install) motion, bend radius, and stiffener materials before quoting the construction.
- DFM moved vias and pads out of the bend zone margin and adjusted coverlay openings at the transition.
- Stiffener extent was set past component areas so the stiffness discontinuity did not sit on the bend boundary; SMT used carrier fixturing for the non-flat panel.
Outcome
- First articles folded into the enclosure without connector harness labor at that interface.
- Mechanical and electrical owners shared one revision-controlled stackup and bend drawing going into DVT.
- Follow-on quantity used the same traveler with only cosmetic silkscreen ECOs.