A footprint can place its electrical pads correctly while its assembly outline or courtyard remains on the wrong mechanical layer. This often becomes visible when the component is flipped to the bottom side or transferred into a project with a different layer convention. Review layer meaning rather than relying only on layer numbers.
Altium’s mechanical-layer documentation describes component layer pairs and mapping by assigned layer type. The paired structure supports side-specific graphics, while untyped layers can require different handling. Confirm how the source library and destination board are configured.
Inventory the footprint’s non-electrical content
Identify assembly graphics, courtyard, body outlines, notes, and any other mechanical information. State which objects should follow the component to the opposite side and which information is genuinely board-level. Do not move fabrication notes into a component layer pair simply because both happen to use mechanical layers.
Compare the library’s layer names, types, and pairing with the destination project. A layer called M13 in one project may serve a different purpose in another. Similar colors also provide no reliable evidence of equivalent meaning.
Exercise placement on both sides
| Check | Expected relationship |
|---|---|
| Top-side placement | Graphics appear on the intended top component layers |
| Bottom-side placement | Side-specific graphics map and orient correctly |
| Assembly drawing | The view uses the intended graphics and labels |
| Clearance review | Courtyard or other relevant geometry remains associated |
Use a footprint with an asymmetric feature for the transfer check. A plain rectangle may conceal a mirror or rotation error. Inspect pin-one references and captions independently because readable text and correct geometry may use different display behavior. Temporarily hide unrelated mechanical layers during review so duplicate outlines cannot make a missing mapped object appear present. Then restore the normal layer set and check that no unintended duplicate graphics were introduced.
Resolve mismatched conventions at the source
- Document the intended destination layer convention.
- Correct the library mapping through the supported workflow.
- Place the corrected footprint in a disposable board copy.
- Verify top and bottom behavior.
- Review affected placed instances before updating the live design.
A local move of graphic primitives can hide the immediate symptom while leaving the library defect in place. If a local exception is necessary, identify it explicitly so the next library update does not overwrite the correction unnoticed.
Close with the corrected layer mapping and verified output views. The assembly-view guide checks how those source graphics are presented to operators after the layer transfer is correct.
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