How to Generate Gerber Files from Protel 99SE: A Complete Engineering Guide

Generating Gerber files from Protel 99SE remains a critical skill for PCB engineers working with legacy designs or maintaining older projects. Although Protel 99SE has been succeeded by Altium Designer, many engineering teams still rely on this robust EDA tool for existing PCB layouts. This comprehensive guide walks you through the complete process of exporting manufacturing-ready Gerber files from Protel 99SE, ensuring your designs translate accurately to fabrication.

Understanding Gerber Files and Their Importance in PCB Manufacturing

Before diving into the export process, it’s essential to understand what Gerber files represent in the PCB manufacturing workflow. Gerber files serve as the universal language between PCB designers and fabrication houses. These files contain layer-by-layer graphical representations of your printed circuit board, including copper traces, solder masks, silkscreen legends, and drill specifications.

Protel 99SE generates Gerber files in the RS-274X extended format, which embeds aperture information directly within the file. This eliminates the need for separate aperture lists and reduces potential communication errors with your PCB manufacturer. Accurate Gerber generation directly impacts manufacturing yield, so following proper export procedures is non-negotiable for professional engineering workflows.

Initiating the CAM Wizard in Protel 99SE

The Gerber export process in Protel 99SE begins with the Computer-Aided Manufacturing (CAM) Wizard. To access this tool, open your PCB design file and navigate to the Tools menu. From the dropdown options, select CAM Wizard. This launches a step-by-step interface that guides you through the entire Gerber generation process.

Upon launching the wizard, an introductory dialog appears. Click Next to proceed to the file type selection screen. Here, you must choose Generate Gerber files from the available options. This selection configures the wizard specifically for Gerber output rather than other CAM formats like ODB++ or IPC-D-356 netlists.

Configuring File Naming Conventions

After selecting Gerber generation, the wizard prompts you to define naming conventions for your output files. Proper file naming is crucial for manufacturing clarity. Most fabrication houses expect standardized extensions that identify each layer type: GTL for top copper, GBL for bottom copper, GTS for top solder mask, GBS for bottom solder mask, GTO for top silkscreen, and GBO for bottom silkscreen.

Establishing consistent naming protocols prevents confusion during the manufacturing review process. Furthermore, clear file names allow automated systems at fabrication facilities to correctly interpret each layer without manual intervention.

Setting Units and Format Resolution

The next configuration screen addresses measurement units and numerical format. For maximum compatibility with PCB manufacturers worldwide, select Inches as your unit of measurement. While metric units are gaining adoption, inch-based specifications remain standard in North American and many Asian fabrication houses.

The format setting determines coordinate resolution. Protel 99SE offers several options ranging from 2.3 to 2.5 format. The 2.5 format provides the highest resolution, accommodating five decimal places after the integer portion. For designs featuring fine-pitch components, high-density interconnects, or tight tolerances, selecting 2.5 format ensures that your Gerber files preserve maximum dimensional accuracy during translation.

Layer Selection and Plot Configuration

The plot configuration screen represents a critical stage in Gerber generation. Here, you must select which layers to include in your output. For a standard two-layer board, you typically need: Top Layer, Bottom Layer, Top Overlay (silkscreen), Bottom Overlay, Top Solder Mask, Bottom Solder Mask, Mechanical Layer, and Keep-Out Layer.

Multi-layer designs require additional internal plane and signal layer selections. Ensure every copper layer and associated manufacturing layer is checked under the Plot section. Equally important is verifying that all checkboxes under the Mirror section remain unchecked. Mirrored layers cause catastrophic manufacturing errors, potentially resulting in reversed copper patterns that render the finished board unusable.

Advanced Plot Options and Aperture Settings

Proceeding through the wizard, you encounter additional plot configuration options. The default selections typically suffice for standard manufacturing requirements. However, certain design scenarios may require adjustments. For instance, embedded components or unusual via structures might necessitate modified aperture settings.

On the character generation screen, select Characters to ensure text elements render properly in your Gerber output. This setting affects how alphanumeric designators and other text objects translate to the final manufacturing files. Improper text settings can result in missing reference designators or illegible markings on the fabricated board.

Completing the Gerber Generation Process

The final wizard screens confirm your settings and initiate file generation. Click Next through these screens, then click Finish to execute the Gerber export. Protel 99SE processes each selected layer and creates corresponding Gerber files based on your configured parameters.

At this stage, your Gerber files exist within the Protel project structure. However, the manufacturing package remains incomplete without drill files, which specify hole locations and dimensions for the fabrication drilling process.

Generating NC Drill Files

Drill file generation follows a separate but equally important procedure. Right-click within the CAM workspace area and select Insert NC Drill from the context menu. This action opens the NC Drill configuration dialog where you specify drill file parameters.

Configure the NC Drill settings as follows: set Units to Inches to maintain consistency with your Gerber files, and select 2.5 format matching your Gerber resolution. Enable the Optimize change location commands option to streamline drill operations during manufacturing. Additionally, check Suppress trailing zeroes to comply with common NC drill formatting standards expected by CNC drilling equipment.

Click OK to generate the drill file. This creates an NC Drill document that specifies every hole location, including component through-holes, mounting holes, and via connections.

Exporting the Complete Manufacturing Package

With both Gerber and drill files generated, you must export these files to a directory accessible for submission to your PCB manufacturer. Right-click on the automatically created CAM folder named “CAM for [your file name]” and select Generate CAM files. This consolidates all manufacturing data into a unified package.

Next, right-click the CAM folder again and choose Export. Select your desired destination directory and confirm the export operation. Upon completion, your chosen folder contains all Gerber files and drill data necessary for PCB fabrication.

Verification and Quality Assurance

Before submitting files to manufacturing, professional engineering practice demands verification. Open your exported Gerber files in a standalone Gerber viewer application to confirm layer alignment, feature integrity, and dimensional accuracy. Many free viewers exist, including GerbView, ViewMate, and online tools provided by PCB manufacturers.

Pay particular attention to layer registration, pad-to-trace connections, and solder mask coverage. Verify that drill holes align with their corresponding pads and that no aperture flash errors appear. This verification step catches potential issues before they become expensive manufacturing defects.

Conclusion

Generating Gerber files from Protel 99SE requires attention to detail across multiple configuration stages. By following the CAM Wizard workflow, properly configuring units and formats, carefully selecting layers without mirroring, and generating complementary NC Drill files, you create a complete manufacturing package ready for professional PCB fabrication. Although Protel 99SE represents legacy software, its Gerber generation capabilities remain fully adequate for producing high-quality manufacturing data when operated correctly. Engineers maintaining legacy designs can confidently use these procedures to interface with modern fabrication facilities worldwide.