Why inspect the exported manufacturing files?
Your PCB design may look correct in the original CAD system, but the manufacturer normally works from exported production files. A separate review lets you examine those files as an independent dataset and confirm that the export contains what you intended to send.
Visual inspection can reveal missing layers, incorrect output, alignment problems, unexpected objects and differences between revisions. Finding such issues before submission is usually faster and less costly than discovering them after fabrication has started.
Review the deliverable, not only the source design
Open the same Gerber, Excellon or ODB++ files that will be delivered to the PCB manufacturer. Avoid relying only on the appearance of the original PCB layout.
Files commonly included in the review
The exact manufacturing package depends on the board and the fabricator, but it commonly includes:
Gerber layers
Top, bottom and internal copper; solder mask; solder paste; silkscreen; board outline and other mechanical layers.
Excellon drill data
Plated and non-plated holes, drill tool definitions and, where applicable, routed slots or contours.
ODB++ data
An integrated manufacturing dataset that can contain layers, drills, components, nets and additional job information.
Supporting information
Fabrication drawings, assembly information, readme files and special instructions requested by the manufacturer.
Gerber inspection checklist
Use the following workflow as a repeatable pre-manufacturing review. It is not tied to one PCB CAD system and can be adapted to your own release procedure.
Open the complete manufacturing dataset
Load all related Gerber and Excellon files into the same workspace. If you received an ODB++ dataset, open the complete job rather than reviewing isolated files.
Viewing the layers together makes it easier to identify missing data, incorrect offsets and files that belong to a different board or revision.
Confirm that every expected layer is present
Compare the loaded files with your intended output list and the manufacturer's requirements. Verify the number of copper layers and check for the required mask, paste, silkscreen, outline and drill files.
- Are the top and bottom copper layers present?
- Are all internal copper layers included and identified correctly?
- Are solder mask and silkscreen files present for the required sides?
- Are plated and non-plated drill data included where needed?
- Is there one clear board outline?
Check the board outline and overall dimensions
Display the outline together with the other layers. Confirm that it encloses the intended board, has the expected shape and does not contain duplicate or unrelated contours.
Use measurement tools to check the overall width, height and any important cutouts. This can also expose an incorrect unit interpretation or scale.
Verify layer alignment and origin
Overlay the copper, mask, silkscreen, outline and drill data. The layers should share the intended coordinate system and line up correctly.
If a layer appears displaced, do not assume that the manufacturer will correct it. Investigate the export settings, units and origin. GerbView also provides alignment tools for examining data created with different origins.
Inspect drill holes, pads and slots
Show the Excellon drill data together with the copper layers and zoom into representative areas. Confirm that holes are centered on the intended pads and that mounting holes, vias and slots appear in the correct locations.
Use the inspection tools to review available drill-tool sizes and coordinates. Where separate files are used, verify that plated and non-plated holes have not been omitted or confused.
Review copper, solder mask and silkscreen
Inspect layers individually and in useful combinations. Transparency and contrasting layer colors can make overlaps easier to understand.
- Look for obviously missing or unexpected copper features.
- Check that solder mask openings correspond with the intended pads.
- Review silkscreen near pads, holes and the board edge.
- Make sure mechanical information is not accidentally included on a production layer.
Measure critical features
Measure dimensions that are important to manufacturing, assembly or enclosure fit. Depending on the board, these may include hole spacing, board-edge clearances, connector positions, cutout sizes and distances between selected features.
GerbView can measure distances, areas and perimeters, with snapping available for accurate selection of pads, tracks and other geometry.
Inspect apertures, tools, components and nets
Query Gerber apertures and Excellon drill tools when you need more information about a selected object. This is useful when investigating an unexpected pad, flash, track or hole.
When component and net information is available in an ODB++ or compatible Gerber X3 dataset, GerbView can display it alongside the PCB layers. Review designators, placement, rotations, pins and connectivity as part of the broader manufacturing and assembly review.
Compare the release with the previous revision
If the board is a revision of an existing product, compare the new Gerber layers with the previously approved files. A visual difference display helps distinguish geometry that was added, removed or changed.
Confirm that the differences match the intended engineering change. Also verify that unchanged layers have not been regenerated with unexpected differences.
GerbView includes a dedicated comparison tool that can compare two Gerber files and visually highlight their differences. Added, removed, and unchanged geometry can be displayed using different colors, making it easier to review changes between PCB revisions.
Warning signs worth investigating
Not every unusual appearance represents an error, but these observations deserve attention before the files are released:
- A layer is empty, missing or unexpectedly small.
- The board outline appears more than once or does not enclose the board.
- Drill holes do not align with their copper pads.
- One or more layers use a different origin, scale or unit interpretation.
- Solder mask openings or silkscreen objects appear in unexpected places.
- The visible content extends far outside the board area.
- Aperture or drill-tool information is missing or produces unexpected geometry.
- The new revision contains changes that are not explained by the engineering change.
Visual inspection is one part of release verification
Gerber inspection does not prove that a PCB is electrically correct or manufacturable under a particular fabricator's rules. It should complement—not replace—electrical checks, automated DFM analysis and the manufacturer's own production review.
Document the completed review
After inspecting the files, keep a record of the approved dataset and revision. GerbView can print PCB data and convert selected layers to formats such as PDF, including layered or multipage PDF documents for review and documentation.
Markup tools can be used to add review notes, text, images, barcodes or QR codes without modifying the original source geometry. When possible, archive the approved manufacturing files together with the review document, fabrication notes and revision identifier.
Inspect PCB manufacturing files with GerbView
GerbView is a Windows application for viewing, printing, measuring, comparing and converting PCB manufacturing data. It supports Gerber RS-274D and RS-274X, Gerber X2/X3 attributes, Excellon drill files and ODB++Design datasets.
You can review multiple layers together, control layer visibility and colors, inspect apertures and drill tools, measure geometry, compare revisions and create PDF documentation without needing access to the original PCB CAD system.
Frequently asked questions
Why should Gerber files be inspected outside the PCB design software?
An independent viewer displays the exported manufacturing files rather than the original PCB design. This helps confirm that the delivered files contain the expected layers, drill data, dimensions and visible board features.
Which files should be included in a PCB manufacturing review?
A typical review includes copper, solder mask, solder paste, silkscreen and board-outline data together with Excellon plated and non-plated drill files. The exact set depends on the board and the manufacturer's requirements.
Can GerbView compare two revisions of a Gerber file?
Yes. GerbView can compare Gerber layers and display their differences, helping you identify geometry that was added, removed or changed between revisions.
Can GerbView inspect ODB++ and Gerber X3 data?
Yes. GerbView supports ODB++Design and Gerber X3 data. When component and net information is included in the dataset, it can be inspected together with the visible PCB layers.
Does visual Gerber inspection replace automated DFM analysis?
No. Visual inspection is useful for finding missing files, unexpected output, alignment problems and revision differences, but it does not replace a manufacturer's automated design-for-manufacturing checks or fabrication requirements.
Related information
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