Build a layer-use map
Assign signals, references, and power paths, then mark where each is required along the outline. Check whether connector pin reassignment, component relocation, or a rigid island can reduce the dense span. The regional rigid-flex guide offers a comparison when the complexity is concentrated around components rather than the interconnect itself.
Six-layer concept review
| Stack feature | Specify | Engineering question |
|---|---|---|
| Density | Layer-by-layer net allocation | Can the dense region be shortened? |
| Interconnects | Required connections between layers | Feasible fabrication sequence |
| Flexible spans | Actual local layer presence | Motion and thickness consequences |
| Prototype evidence | Unresolved electrical and mechanical questions | Decision-specific measurements |
Review the interconnection sequence
List the required layer-to-layer connections and ask the fabricator for a proposed via and lamination strategy. Distinguish design intent from a process already confirmed as available. Show bond layers, copper assumptions, and material candidates so the proposed stack can be reviewed as a whole. Consult via planning before placing dense interconnect features near regions expected to bend.
Plan separate electrical and mechanical evidence
Define the electrical checks for the dense routing and the mechanical checks for the flexible sections. Consider how coupons or representative assemblies will reveal the most consequential unknowns. A successful continuity test alone does not settle installed movement or thermal behavior. Tie each prototype measurement to a design decision and preserve the exact stack revision used for the test.
Before you release the design
- Show why six conductors are needed.
- Map dense and flexible regions separately.
- Request a reviewed via and bonding sequence.
- Define the prototype's acceptance questions.
Watch points
- Do not publish a six-layer concept as an available manufacturing service without confirmation of the actual construction.
Practical questions
Does six-layer flex require repeated movement capability?
No. State whether flexibility serves installation, packaging, or service motion, and design the qualification around that purpose.
Is a rigid-flex version automatically preferable?
No. Compare routing, assembly, enclosure, and fabrication requirements at the complete-system level before choosing.
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.