Gerber data needs an unambiguous manufacturing context
A Gerber layer describes graphical features used in PCB production. The set may include copper layers, solder-mask openings and legend artwork. It is not, by itself, a complete assembly BOM or a functional test specification. Fabrication also needs the correct drill and mechanical information and the requirements that define the finished board.
Ucamco, the format’s developer, describes Gerber Job as a way to carry fabrication information such as materials, finish and overall thickness in a machine-readable form. Confirm the formats accepted by the recipient. Include clear fabrication documentation whenever a required characteristic is not unambiguously represented in the data.
Identify every layer and operation
Extended Gerber, commonly called RS-274X, carries the aperture definitions needed to interpret its image data within the file. Legacy RS-274D workflows may depend on a separate aperture table. X2 adds attributes that help identify the meaning of data. Check the recipient’s accepted export settings instead of assuming that changing a filename converts the format.
Name files so their function and stack position can be understood, and provide a layer list. Do not rely on an extension alone: CAD tools and export jobs use different naming conventions. A layer called “top” must not be confused with the top solder mask or top paste layer.
- Include every required copper, mask and legend layer for the released board.
- Identify plated and non-plated drilling and define routed slots or special holes.
- Provide a closed outline with the intended cutouts, units and critical dimensions.
- State the stackup, material, finished thickness and copper, finish and tolerances in the fabrication requirements.
- Keep assembly paste, placement and drawing data clearly identified rather than mixing them with fabrication layers.
Inspect the exported result, not only the CAD project
Open the exact files that will be sent in an independent viewer. Compare copper, mask, drills and outline in the same coordinate system. Check a known dimension to catch unit or scale errors. Inspect connector edges, fine-pitch pads, holes and unusual cutouts, where an export mismatch can be expensive.
Review top and bottom orientation deliberately. A fabrication dataset and an assembly drawing may use different presentation conventions; arbitrary mirroring to make a screenshot look familiar can create an incorrect release. Verify the export convention with the manufacturer when it is unclear.
Remove stale revisions from the delivery archive. If a file is regenerated, rebuild and recheck the released set so a new drill file is not paired with old copper. A readme or manifest should name the board, revision, file roles and the drawing that controls manufacturing requirements.
Close the review before production
Ask the fabricator to return any conflicts or requested changes against the named revision. Confirm the approved stackup and special-process requirements before authorizing manufacture. Keep a copy of the files and approvals actually released.
For an assembly quotation, add the BOM, placement file, assembly drawing and any programming or test requirements. A Gerber preview that looks correct cannot confirm part identity, fitted variants or complete assembly functionality.
Technical references
- Ucamco: Gerber Job and fabrication documentation
- Ucamco: official format specifications and test files