PCB Gerber Files: Common Issues and Ways to fix Them

Sep 10, 2024

Gerber files are an essential feature of printed circuit board (PCB) assembly or manufacturing, which serves as an industry-standard format for conveying detailed design information to manufacturers. These files translate complex PCB designs into a language that fabrication machines can understand so that every layer of the board-from copper traces to solder masks can produced accurately. Without Gerber files, manufacturers cannot produce PCBs that match the precise specifications set by designers, which ultimately leads to errors, delays, and increased costs.

Despite their critical role in the production process, working with Gerber files is more challenging than it seems. Various issues can arise, leading to costly mistakes or even rendering the PCB unusable. This post offers some of the most common problems associated with Gerber files and provide insights into mitigating these issues.

Common Problems Associated with Gerber Files
The following are a few common issues with Gerber files and ways to fix them.

Incomplete or missing files: One of the most common issues with Gerber files is submitting incomplete or missing files. Each layer of the PCB—copper layers, solder masks, silkscreens, and drill files requires its own Gerber file. The manufacturer cannot produce the board correctly if any of these files are missing.
In this situation, always double-check that all necessary files are included before submitting them to the manufacturer.
Incorrect Drill Files: Drill files are important because they define the holes that need to be drilled in the PCB. If the drill file is incorrect, it can lead to holes being drilled in the wrong locations or not drilled at all. This issue can result in components being unable to be mounted or electrical connections being broken.
So, always verify that the drill files are accurate and correspond correctly to the rest of the design.
Inconsistent File Formats: PCB manufacturers might require different Gerber file formats and settings. Issues can arise if the files submitted do not match the manufacturer’s specifications, leading to delays or even rejected orders. So, before submitting Gerber files, review the manufacturer’s specifications for file formats and settings.
Misaligned Layers: Layer misalignment occurs when the different layers of the PCB do not align correctly, often due to errors in the Gerber files. This can cause issues like short circuits, open circuits, or components not fitting properly. Use alignment marks or fiducials in your design to help ensure that layers align correctly during manufacturing. Also, thoroughly inspect the Gerber files using a Gerber viewer to check for any alignment issues before submission.
Overlapping Features: Overlapping features, like traces, pads, or text, can cause significant issues during manufacturing. These overlaps might lead to short circuits, especially when copper layers are involved, or they may affect the clarity of silkscreen text. In such case, conduct a thorough Design Rule Check (DRC) using your PCB design software to identify and correct any overlapping features.
Composite Layers: Many CAD software packages may split a copper layer into several Gerber files. This is commonly observed in layers that have filled areas. The software will create separate files for traces, clearances, and copper pour for these layers. The issue occurs due to a specific option in CAD layout software. Hence, double-check the files with a Gerber Viewer and correct the settings in the software.
Incorrect Aperture Definitions: Gerber files use apertures to define the shapes and sizes of the features on the PCB, such as pads and traces. If the aperture definitions are incorrect or missing, the resulting PCB can have features that are too large, too small, or incorrectly shaped, that will lead to functionality issues or even board failure. So, ensure that aperture definitions are correctly set up in your PCB design software.

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