Direct Answer
Generating Gerber data from a different PCB design software follows the same core principles regardless of the ECAD tool you use. The Gerber format (RS-274X) is an open, standardized vector format that describes each layer of your PCB—copper, solder mask, silkscreen, drill, and outline—as separate files. As long as you export the correct layers with proper units, aperture settings, and include the NC drill file, your Gerbers will be manufacturable by Omini or any other PCB fab. Switching tools doesn’t require relearning the concept; it’s about mapping your new software’s export options to the universal Gerber requirements.
The key is consistency: always verify your Gerber output before sending it to manufacturing. Use a free Gerber viewer like GerbView or GC-Prevue to inspect each layer for alignment, completeness, and correctness. Confirm that your drill file matches the copper layers in registration and that essential layers—top/bottom copper, solder mask, silkscreen, and board outline—are present. Omitting mechanical layers or fabrication notes is usually safe unless your fab specifically requests them, but never skip the drill file or misalign its origin with the copper data. Once verified, your Gerbers are ready for Omini’s DFM checks and fabrication workflow.
Understanding Gerber Format Fundamentals
Gerber files are not a single file but a set of ASCII-based vector files, each representing one physical layer of the PCB. The RS-274X standard, the most widely used variant, includes embedded aperture definitions and supports positive/negative polarity, which allows for efficient representation of copper pours, pads, and traces. When you generate Gerbers from your ECAD tool, you’re essentially translating your internal design database into this standardized format that fabrication equipment can interpret directly.
Each Gerber file corresponds to a specific layer: GTL (top copper), GBL (bottom copper), GTS (top solder mask), GBS (bottom solder mask), GTO (top silkscreen), GBO (bottom silkscreen), and a drill file (often .drl or .txt). The board outline is typically included in a mechanical layer or as part of the outline Gerber (GM1, GM2, etc., or sometimes in the outline layer of the copper files). Critical to success is ensuring that all layers share the same origin point (usually the lower-left corner of the board) and that units (mm or inches) are consistent across files and explicitly stated in the fab notes. Mismatched origins or units are a common source of registration errors that lead to misaligned vias, missing features, or shorts.
Modern ECAD tools automate much of this process, but the engineer must still verify the output. For example, some tools default to generating negative plots for solder mask or silkscreen, which is correct for RS-274X but can confuse viewers if not interpreted properly. Others may omit the drill file unless explicitly selected, or they may generate separate files for plated and non-plated holes without clear labeling. Always consult your software’s Gerber generation guide, but treat it as a starting point—not a guarantee—of correctness.
Step-by-Step Gerber Generation Across Popular ECAD Tools
While interfaces vary, the Gerber export workflow in major PCB design tools follows a consistent logic. In Altium Designer, you use the “File > Assembly Drawings > Generate Gerber Files” command, which opens a dialog where you select layers, set units (mm preferred), configure aperture settings (usually auto-generated), and enable the drill file output. You must manually ensure that the drill layer is included and that the “Plot Drill Holes” option is checked. Altium also allows you to generate an ODB++ file directly, which bundles layer data, drill information, and stackup into a single folder—useful for complex designs but not required for Omini.
In KiCad, the process is accessed via “File > Plot.” You select the layers to plot (e.g., F.Cu, B.Cu, F.Mask, B.Mask, F.SilkS, B.SilkS, Edge.Cuts), choose Gerber as the format, and set the output directory. Crucially, you must click “Generate Drill Files” separately under the same menu to produce the .drl file. KiCad defaults to mm and uses a fixed origin, which reduces alignment risk, but you should still verify that the Edge.Cuts layer accurately defines the board outline without extra lines or arcs that could be misinterpreted as copper.
For Autodesk Fusion 360 (Electronics workspace), Gerber generation is under “Manufacturing > Gerber.” You select layers, define units, and enable drill output. Fusion 360 tends to be more opaque about aperture settings, but it generally generates valid RS-274X files. However, users have reported occasional issues with silkscreen font scaling or missing thermal reliefs in pours, so visual inspection is essential. Similarly, in Zuken CR-8000 or Cadence Allegro, the Gerber output is robust but often buried in CAM-specific menus; Allegro uses the “Manufacturing > Generate/Export” flow with extensive layer mapping options that require careful setup to avoid omitting internal planes or mislabeling power layers.
Regardless of the tool, the verification step is non-negotiable. Open each Gerber file in a viewer and toggle layers on and off to confirm that copper pours are intact, silkscreen doesn’t overlap pads unnecessarily, solder mask openings match pad sizes, and the drill file shows holes in the correct locations relative to copper features. A single misaligned layer can turn a functional design into a scrap panel.
Essential Layers and What to Include (or Exclude)
Knowing which layers to include—and which to avoid—is critical for clean Gerber generation. The mandatory layers for any standard rigid PCB are:
- Top copper (GTL or .cmp)
- Bottom copper (GBL or .sol)
- Top solder mask (GTS or .stc)
- Bottom solder mask (GBS or .sts)
- Top silkscreen (GTO or .plc)
- Bottom silkscreen (GBO or .pls)
- Drill file (often .drl, .txt, or .xnc)
- Board outline (typically in a mechanical layer or Edge.Cuts in KiCad)
Optional but sometimes required layers include:
- Internal power/ground planes (if multi-layer, named GP1, GP2, etc., or internal copper layers)
- Fabrication notes (as a separate text file or Gerber layer—only include if your fab requests it)
- Assembly drawings or pick-and-place files (separate from Gerbers, for PCBA)
Layers to generally exclude unless explicitly asked for by your fab:
- Mechanical layers with dimensions, notes, or tooling holes (unless part of the official outline)
- Skew or mirror layers
- Fabrication-specific layers like rout paths or scoring lines (unless generated by the fab)
- 3D model files or STEP exports (not part of Gerber set)
Including unnecessary layers increases the risk of confusion or misinterpretation during CAM processing. For example, a dimension layer with text might be mistaken for silkscreen, or a notes layer with arrows could be interpreted as copper. Always strip your Gerber set down to the essentials unless your fab’s documentation specifies otherwise. Omini’s standard workflow assumes Gerber RS-274X with the seven core layers listed above; additional layers are only used if explicitly coordinated in advance.
Verifying Gerber Output: Tools and Checks
Generating Gerbers is only half the battle; validation is where you prevent costly rework. The first step is visual inspection using a Gerber viewer. Free tools like GerbView (from GraphiCode), GC-Prevue, or online viewers such as Gerber Lookup allow you to load each layer and toggle them to check alignment. Look for:
- Copper pours that are broken or disconnected
- Solder mask openings that are too small (causing solder mask defined pads) or too large (risking shorts)
- Silkscreen that overlaps pads or vias (which can hinder assembly)
- Drill holes that are missing, offset, or incorrectly sized
- Board outline that doesn’t enclose all copper features or has stray lines
Beyond visual checks, run a Design for Manufacturability (DFM) analysis on your Gerbers. Many ECAD tools have built-in DFM checks, but standalone tools like Valor NPI, CAM350, or even free alternatives can detect issues invisible to the eye. These include:
- Annular ring violations (where the drill breaks through the copper pad)
- Acid traps or slivers (narrow copper features that can etch unevenly)
- Missing solder mask dams between fine-pitch pads
- Insufficient copper-to-edge clearance
- Drill-to-drill or drill-to-copper spacing issues
Omini performs its own DFM review on incoming Gerbers, but catching these issues early saves time and reduces back-and-forth. For example, a common oversight is generating Gerbers with solder mask expansion set to zero, resulting in mask-defined pads that increase assembly variability. Another is forgetting to enable tenting for vias in BGA areas, which can lead to solder wicking during reflow. Use resources like Omini’s guide on Common DFM Issues and How to Avoid Them in PCB Design to align your checks with industry best practices.
Special Considerations: Rigid-Flex, Heavy Copper, and High-Frequency Designs
While standard rigid PCBs follow the Gerber rules outlined above, specialized designs require additional attention. For rigid-flex PCBs, you must generate separate Gerber sets for the rigid and flex regions, or use a layered approach where flex areas are defined by specific layers (e.g., flex coverlay, stiffener layers). The bend areas need accurate layer definitions to prevent cracking during flexing, and stiffeners must be clearly outlined in their own Gerber layer. Simply using the same Gerber settings as a rigid board will result in missing flex layers or incorrect coverlay openings—consult your fab’s rigid-flex guide before exporting.
Heavy copper PCBs (typically 3 oz/ft² or more) present unique Gerber challenges. The increased copper thickness requires wider trace spacing to prevent etching issues, and thermal reliefs must be larger to accommodate the higher thermal mass during soldering. If your Gerber files don’t reflect these adjustments—say, by using standard spacing rules for 1 oz copper—you risk shorts during fabrication or poor solder joints during assembly. Refer to Omini’s analysis of Common Failures in Heavy Copper PCB and How to Avoid Them in the Design Stage for specific Gerber-related pitfalls like inadequate annular rings or missing thermal reliefs in high-current paths.
High-frequency designs introduce signal integrity concerns that affect Gerber generation indirectly but critically. Impedance-controlled traces require precise width and spacing, which must be preserved in the Gerber output. Any rounding or aperture approximation in the Gerber file can alter impedance. Additionally, ground plane stitching vias must be correctly placed and sized in the drill file to prevent cavity resonances. While the Gerber format itself doesn’t encode electrical properties, the geometric accuracy of the exported data is paramount. For deeper insight, see Omini’s overview of High Frequency PCB Design Challenges and How to Overcome Them, which discusses how Gerber accuracy impacts RF performance.
Omini’s Acceptance Criteria and Best Practices
Omini accepts Gerber RS-274X as the standard format for the vast majority of projects, and ODB++ for those who prefer a single-package approach with embedded stackup and drill data. Neither format is inherently superior for basic to moderate complexity designs; Gerber is widely supported, human-readable (in part), and sufficient when layers are correctly generated and verified. ODB++ reduces the chance of layer mismapping but requires the fab to support its import—Omini does, but Gerber remains the safer default unless your design has complex layer stacking, blind/buried vias, or material variations that benefit from embedded metadata.
Regardless of format, always include a fab notes file (README.txt or similar) that specifies:
- Units used (mm or inches)
- Layer-to-file mapping (e.g., GTL = Top Copper)
- Drill file format and units
- Any special requirements (e.g., impedance control, surface finish, material)
- Your contact information and revision number
This file prevents misinterpretation during CAM setup. Never assume the fab knows your layer naming convention—explicit mapping is cheap insurance. Finally, run your Gerbers through a final check using the same viewer you’ll use for inspection, and confirm that the output matches your design intent exactly. If you’re switching ECAD tools, treat the first Gerber set as a prototype: verify it thoroughly before assuming the tool’s defaults are correct. With disciplined layer selection, origin alignment, and validation, generating Gerbers from any PCB design software becomes a reliable, repeatable step in your manufacturing workflow.