Layer orientation errors can turn an otherwise correct design into the wrong physical board. Use explicit layer naming and an approved stack order, then inspect the exported package from a consistent viewing convention. Assembly-side interpretation needs a separate check because component rotation and mirroring conventions can differ between systems.
Publish the layer order
List copper layers from one named board face to the other and identify mask, marking and mechanical outputs. Keep the same identifiers in the CAD setup, file names and stack-up drawing. Avoid relying on alphabetical file order to communicate the construction.
Do not add unrequested mirroring
Generate outputs using the agreed manufacturing workflow. If a receiver requests a different orientation convention, document it and validate the result. Manually mirroring a layer because it looks like a bottom view can create an error in a format that already carries the correct geometry.
Review asymmetrical features
Use an asymmetric outline, connector or known pad arrangement to check the interpretation. Compare top and bottom markings, holes and copper in an independent viewer. A symmetric board can hide a reversed layer more easily, so choose a feature that proves orientation.
Check assembly coordinates independently
Confirm origin, units, side and rotation conventions for component-position data. Reconcile a few unambiguous components with the assembly drawing, including polarized and bottom-side parts. Resolve differences before programming placement equipment.
Release checklist
- Use explicit stack order and layer names.
- Inspect exported layers without ad hoc transformations.
- Verify an asymmetric reference feature.
- Confirm placement origin, side and rotation conventions.