Gerber / Excellon PCB Viewer will not open? Format and display troubleshooting
Troubleshoot Gerber / Excellon PCB Viewer by checking signatures, versions, units, coordinates, and browser resources while preserving the source.
Do not rename or overwrite the source first
Make a sample copy and retain the original delivery, size, producer version, and exact error. For a four-layer board, identify top/bottom copper, inner layers, masks, silkscreens, outline, and drills. Toggle each layer and compare outlines. A globally shifted drill layer often means Excellon and Gerber were exported from different origins.
Recommended troubleshooting order
- Test the page example or a smaller known-good file to confirm browser functionality.
- Check that the file signature matches its extension and it is not a downloaded HTML error page.
- Compare the supported formats and size limit with the specialist checks below.
- Close other heavy tabs and retry in current Chrome or Edge.
- If it still fails, re-export from the producing application and verify in authoritative specialist software.
Checks for this format
- Layer roles match the design rather than relying only on extensions
- The outline is closed and copper/drills remain within plausible bounds
- PTH/NPTH drills are not globally shifted or scaled by a unit error
- Top/bottom orientation is explicit and silkscreen avoids exposed pads
Common errors and fixes
The ZIP opens but every layer is unknown
Manually map layers when filenames are unusual; automatic detection is not a design manifest.
Pads or regions are missing
Aperture macros, region fills, or legacy dialects may be incomplete; verify in source CAD and fabricator CAM.
When a browser tool is insufficient
- Filename-based layer detection can be wrong and must be reviewed
- Complex aperture macros, step-repeat, and vendor dialects may be incomplete
- No replacement for DRC, netlist comparison, or fabrication CAM review
A visible preview only proves this parser read some structures. It does not prove engineering, manufacturing, scientific, business, or clinical compliance. Keep validation records from the source and receiving systems.
Privacy and safety
The tool reads files locally and does not upload them to FreeTool for parsing. Troubleshooting screenshots, CSV exports, and downloads can still contain sensitive data; de-identify before sharing and clear copies from shared devices.