Create the region map first
Name each rigid island and flexible span, then associate it with a complete section. Altium documents region-specific substacks as part of its rigid-flex workflow. Use that capability to communicate layer presence, while keeping a fabrication drawing that can be reviewed without opening the CAD project. The stackup drawing guide explains the minimum region-to-section relationship.
Rigid-flex region definition
| Stack feature | Specify | Engineering question |
|---|---|---|
| Rigid island | Copper and dielectric sequence | Routing and component requirements |
| Flexible span | Local conductor and cover construction | Installed geometry and service duty |
| Transition | Layer terminations and bonding details | Fabrication and mechanical review |
| Model | Region thickness and bend definitions | Consistency with release drawings |
Show the transition explicitly
Locate rigid boundaries, cover materials, internal bonding, and interconnect features near the transition. Make the intended flex exit and component or connector loading visible. Ask the fabricator to review the transition construction rather than drawing only the center of each region. Consult architecture selection if the rigid region exists only to provide mechanical support.
Keep the folded model and release package aligned
State bend angle, radius definition, and installation order where relevant. Check the product envelope with the proposed finished region thicknesses. Use the model to find interference and communicate intent; qualify material and assembly behavior separately. When an approved stack changes, update the region map, electrical model, drawing sections, and folded representation together so different teams do not work from incompatible constructions.
Before you release the design
- Name every distinct region.
- Map each region to a section drawing.
- Show layer continuity across boundaries.
- Review transition details before layout release.
- Keep folded and flat data synchronized.
Watch points
- A folded CAD model does not demonstrate fatigue, bond integrity, or manufacturing tolerance.
Practical questions
Can rigid regions have different stacks?
A regional proposal can contain different sections, but the complete interconnection and fabrication approach must be reviewed.
Is a stiffener a rigid-flex region?
Not by itself. A passive support and an electrically interconnected rigid circuit section are different construction concepts.
Technical references
References support the material or design context. Check the exact grade, part number, document revision and project conditions before release.Updated 27 September 2026 · Technical content policy · Engineering guidance supports project review; the agreed drawing defines the build.