How to Generate Gerber and Drill Files in Altium Designer 23.5.1

Generating Gerber and drill files in Altium Designer 23.5.1 is an essential step in transitioning your PCB design from the digital environment to physical fabrication. Gerber files serve as the universal language between design engineers and PCB manufacturers, containing all the critical layer information required for accurate board production. This comprehensive guide walks you through the complete workflow for exporting manufacturing-ready files from Altium Designer 23.5.1, ensuring your designs translate flawlessly to the fabrication floor.

Understanding Gerber and Drill File Fundamentals

Before diving into the export process, it is worth understanding what these files actually represent. Gerber files conform to the RS-274X format (extended Gerber), which has become the de facto industry standard for PCB fabrication data. Each Gerber file corresponds to a specific layer of your PCB, including copper layers, solder mask, silkscreen, and paste layers. The format uses vector-based aperture definitions to describe traces, pads, and other features with precision.

Drill files, also known as NC (Numerical Control) drill files or Excellon files, contain the coordinate data and tool specifications for all through-holes, vias, and other drilled features on your board. These files follow the Excellon format and work in conjunction with Gerber data to provide manufacturers with complete fabrication instructions. Without accurate drill files, your PCB cannot be properly manufactured regardless of how perfect your Gerber outputs are.

Configuring Gerber File Output in Altium Designer 23.5.1

The Gerber generation process in Altium Designer 23.5.1 begins from the main menu interface. Navigate to File → Fabrication Outputs → Gerber Files to access the Gerber Setup dialog. This dialog provides comprehensive control over every aspect of your Gerber output, and proper configuration here directly impacts manufacturing quality.

Layer Selection and Configuration

Upon opening the Gerber Setup interface, your first task is selecting the appropriate layers for export. Click on the Layers to plot tab to view all available layers in your design. For most standard PCB projects, you should use the Plot Layers → Select Used option, which automatically identifies and selects all layers containing design data. This approach prevents both the omission of critical layers and the inclusion of empty layers that could confuse the manufacturing process.

For multilayer boards, ensure that all copper layers are selected along with their corresponding mechanical layers. A typical four-layer board requires at minimum the following outputs: Top Layer, Ground Plane, Power Plane, Bottom Layer, Top Overlay, Bottom Overlay, Top Solder, Bottom Solder, Top Paste, and Bottom Paste. Additionally, verify that your board outline is included, typically on the Keep-Out Layer or a designated mechanical layer per your design rules.

Advanced Settings Configuration

The Advanced tab within the Gerber Setup dialog contains parameters that significantly affect output quality. Here, you should configure the aperture settings, film size, and other critical parameters that align with your fabricator’s requirements.

Set the Format to 2:5 (2 integer digits, 5 decimal digits) for metric units or 2:4 for imperial units, providing sufficient precision for modern manufacturing tolerances. Most fabricators accept either format, but confirming their preference eliminates potential issues. The Leading/Trailing Zeroes setting should typically match your fabricator’s specifications, with most modern facilities preferring suppressed leading zeros.

Under aperture handling, enable Embedded apertures (RS274X) to ensure aperture definitions are contained within the Gerber files themselves rather than requiring separate aperture lists. This self-contained approach reduces file management complexity and virtually eliminates aperture mismatch errors during manufacturing.

Once all settings are configured correctly, click Apply or OK to generate the Gerber files. Altium Designer will create a CAM document (.Cam) which opens automatically. You can close this preview document without saving, as the actual Gerber files have already been written to your project’s output directory.

Generating NC Drill Files

With Gerber files successfully exported, the next critical step is generating the corresponding NC drill files. Navigate to File → Fabrication Outputs → NC Drill Files to open the NC Drill Setup dialog.

Drill Output Parameters

The NC Drill Setup dialog presents several important configuration options. Under Units, select either Metric or Imperial based on your design units and fabricator requirements. Consistency between your Gerber and drill file units prevents scaling errors that could render your board non-functional.

The Format field should match your Gerber file configuration. Using 2:5 for metric or 2:4 for imperial maintains consistency across all fabrication outputs. Enable Leading/Trailing Zeros suppression according to your fabricator’s specifications—this setting must align with your Gerber configuration to ensure proper coordinate alignment.

Under Coordinate Positions, select Reference to Relative Origin if you have defined a relative origin in your PCB design, or Reference to Absolute Origin for designs using absolute coordinates. The choice depends on your design setup, but relative origin typically offers more flexibility.

Handling Drill Data Import Dialog

After clicking OK in the NC Drill Setup dialog, Altium Designer may present an Import Drill Data dialog. This dialog typically appears when the software detects existing drill data or requires confirmation of hole pair assignments for blind and buried vias. In most cases, accepting the default settings and clicking OK produces correct results for standard through-hole designs.

For designs incorporating blind or buried vias, carefully verify the drill pair assignments in this dialog. Each via type must be associated with the correct layer pair to ensure proper manufacturing. Incorrect drill pair assignments result in vias that either fail to connect the intended layers or create short circuits.

The NC drill export generates several output files including the main drill file (.DRL or .TXT extension depending on configuration), a drill tool report, and potentially separate files for different drill layer pairs. All these files should be included in your fabrication package.

Verifying and Packaging Output Files

After generating both Gerber and drill files, verification before submission to your fabricator is essential. Altium Designer 23.5.1 outputs these files to a designated project output folder, typically named Project Outputs for [ProjectName]. Navigate to this folder to locate all generated files.

A complete fabrication package for a standard four-layer board typically includes the following file types: copper layer Gerbers (.GTL, .GBL, .G1, .G2), solder mask Gerbers (.GTS, .GBS), silkscreen Gerbers (.GTO, .GBO), paste mask Gerbers (.GTP, .GBP), board outline Gerber (.GKO or .GM1), and NC drill files (.DRL, .TXT, or .XLN).

Consider using a standalone Gerber viewer to verify your outputs before submission. Tools like GerbView, ViewMate, or online viewers provided by PCB fabricators allow you to visually inspect each layer for correctness. Check for proper alignment between layers, verify drill hole positions relative to pads, and confirm that all features appear as intended.

Best Practices for Manufacturing Success

Maintaining consistent unit systems across all outputs prevents scaling discrepancies that cause manufacturing failures. Document your export settings in a project template to ensure repeatability across design revisions. Always include a README file or fabrication notes specifying your layer stackup, material requirements, and any special manufacturing instructions.

Communicate with your PCB fabricator regarding their preferred file formats and naming conventions. While the Gerber and Excellon formats are standardized, fabricators may have specific preferences for file organization, naming schemes, or additional documentation requirements. Adhering to these preferences streamlines the manufacturing process and reduces the likelihood of fabrication errors.

Generating Gerber and drill files in Altium Designer 23.5.1 becomes straightforward once you understand the configuration options and their implications. By following this systematic approach and verifying your outputs before submission, you can confidently transition your PCB designs from concept to production with minimal risk of manufacturing issues.