Name the alignment that matters
Identify the features that must register: contact fingers to the tail edge, openings to pads, reinforcement to a component area, or a long branch to an enclosure datum. Link those requirements to tolerance planning. Distinguish global length change from local registration; one overall outline measurement may not reveal the interface problem.
Dimensional review stages
| Requirement | Question to resolve | Drawing or process record |
|---|---|---|
| Material input | What exact construction is proposed? | Grade and regional layer record |
| Fabrication registration | Which layers must align? | Critical feature overlay |
| Finished inspection | What condition and restraint are used? | Measurement method and datums |
| Compensation | Who approves and controls adjustments? | Revision-linked engineering record |
Discuss material and process context
Record the laminate, copper arrangement, bonding construction, and relevant thermal or conditioning history with the fabricator. The datasheet guide helps preserve specimen and test context when comparing dimensional information. Do not transplant a typical material value directly into a guaranteed finished-part tolerance or independently rescale CAD artwork without an agreed process.
Use a measured first-article comparison
Choose meaningful datums and inspect the actual critical relationships on representative parts. Agree whether measurements occur before or after assembly or conditioning. If compensation is proposed, record who controls it, which file set it affects, and how the resulting product is verified. Preserve the approved source geometry separately from manufacturing adjustments to avoid accumulating hidden corrections across revisions.
Before you release the design
- State critical feature-to-feature relationships explicitly.
- Keep free-state shape separate from fixture-based measurements.
- Request process feedback before imposing narrow tolerances.
- Record any approved artwork compensation and its purpose.
Watch points
- A typical material test value is not a complete process capability statement.
Practical questions
Should the designer enlarge the outline to allow for shrinkage?
Only under a coordinated, documented agreement with the fabricator. Uncontrolled scaling can misalign layers or conflict with the supplier's own compensation workflow.
Does a stable base film guarantee final registration?
No. The finished construction and its processing include additional layers and steps. Verify the actual functional relationships on the finished part.
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.