A rigid-flex board can display a convincing outline while a region is assigned to the wrong substack. The error may remain hidden until layer views, drilling, or fabrication documentation are examined. Treat region geometry and stack assignment as separate items that must agree.
Altium’s rigid-flex documentation describes assigning substacks to board regions and aligning them through the thickness direction. This provides a CAD representation of construction intent, but the region map still needs reconciliation with the supplier-reviewed build.
Create an explicit region map
Give each rigid and flexible region a distinct identity. Record its boundary, assigned substack, included copper layers, and associated fabrication drawing reference. Avoid relying only on display color, because colors can be changed or lost in exported review images. Add a readable region name to the construction drawing.
Check shared boundaries after an outline edit, split operation, or design-mode conversion. Small slivers, gaps, or overlapping regions can be difficult to see at full-board scale. Inspect the locations where the physical construction changes and where important conductors cross.
Trace layer continuity
| Boundary question | Evidence |
|---|---|
| Which copper layers continue? | Substack definitions and layer-by-layer review |
| Where does rigid material stop? | Dimensioned region boundary |
| Which drilling applies? | Hole span and regional construction review |
| Does the drawing agree? | Region labels and stackup cross-references |
Follow critical routes across the transition using their physical layer identity, not only a layer name such as “inner one.” A layer’s position within a local region can differ from its role in the complete construction. Resolve any naming ambiguity before release.
Review after changing a region
- Confirm the edited boundary matches mechanical intent.
- Read back the assigned substack for each affected region.
- Inspect copper and holes around the transition.
- Regenerate construction drawings and relevant outputs.
- Obtain clarification of any supplier construction conflict.
A folded three-dimensional view is useful for understanding the shape but does not independently prove layer continuity or manufacturing feasibility. Keep geometric fit, electrical routing, and construction review as connected but distinct checks.
Document exceptions such as special local constructions explicitly. Do not imply that every region with the same visible color shares the same materials or thickness. The final region map should allow a reviewer to locate a point on the board and determine which approved construction applies there.
Preserve the reviewed map with the fabrication package. Later boundary changes can then be compared against a defined baseline, rather than reconstructed from screenshots of an earlier folded model.
Move from reading to a build-ready project
Use the fabrication and assembly checklists to prepare drawings, production files and test requirements.
Open the DFM checklist