Gerber files are the foundation of printed circuit board (PCB) manufacturing. They provide manufacturers with complete information about the geometry of traces, pads, solder masks, and all other board layers. The quality of Gerber file preparation affects not only the accuracy of the production process, but also lead times, costs, and the risk of manufacturing errors.

Understanding how Gerber files are used – and why their completeness is critical – helps customers avoid issues from the very beginning and ensures a seamless transition from design to a fully manufactured PCB.

Gerber files are the standard data format used in the production of printed circuit boards (PCBs). The format originates from Gerber Systems Corp., the company that first introduced it. These files contain comprehensive information on the placement and geometry of PCB features such as pads, traces, solder masks, and silkscreen layers. Their primary purpose is to translate a design created in CAD software into manufacturing instructions that PCB fabrication facilities can interpret.

In a typical PCB layout, each layer is exported as a separate Gerber file. In more advanced designs, however, multiple layers may be combined to generate additional documentation, such as fabrication drawings or assembly files.

Gerber data is stored in ASCII text format, meaning each file includes configuration parameters, hole definitions, aperture descriptions, coordinate data for all elements, and commands that govern how features are drawn. Gerber files can be opened in dedicated viewer applications that render a graphical representation of the PCB – similar to what is shown in CAD tools. This allows manufacturers to perform a preliminary review and run DFM (Design for Manufacturing) checks, including verification of track spacing and clearances.

Gerber files serve as the primary communication interface between PCB designers and manufacturers. Without them, design data would remain locked in proprietary software formats, preventing its direct use in fabrication processes.

Gerber files present design intent and detailed information regarding trace geometry, pads, solder masks, and all remaining PCB layers in a clear, unambiguous, and tool-agnostic format. This eliminates the risk of misinterpretation and ensures the faithful execution of the original design.

Gerber files play a pivotal role in automated PCB production, where each board layer must be reproduced with micrometer-level precision. They act as machine-readable instructions for CAM systems, lasers, CNC drilling machines, and SMT assembly lines, enabling the physical creation of an electronic product. They are also integral to quality assurance systems such as AOI and AXI, where they are used to generate reference models that help detect deviations from the intended design.

Without the Gerber standard, the current scale of electronics manufacturing – from rapid prototyping to mass production – would simply not be feasible.

From the perspective of EMS providers, Gerber files constitute mission-critical production documentation. They are used to plan technological processes, estimate costs and delivery timelines, and verify whether a design is compatible with available manufacturing capabilities. Any deficiencies, such as missing layers or incorrect file structures, may result in production downtime, engineering changes, or material wastage.

Therefore, proper preparation of Gerber files is a fundamental prerequisite for project success. It ensures a smooth transition from a designer’s concept to a physical PCB – the core building block of modern electronic products.

The earliest commonly used Gerber format was RS-274-D, which contained only XY coordinates along with basic drawing and flash commands. Aperture definitions had to be assigned separately, increasing the risk of errors and limiting automation.

This format was later replaced by RS-274-X (often referred to as “Gerber X”), which integrates aperture definitions and other key parameters into each file, eliminating manual configuration and streamlining both design and production workflows. Today, it is the standard format used in PCB design software, accounting for the production of approximately 90% of all PCBs currently designed worldwide.

The most recent evolution is Gerber X2, which supports additional metadata, such as pad functions, layer types, and impedance-related parameters, further enhancing clarity and traceability during manufacturing.

Despite these developments, the Gerber format remains compatible with both traditional photoplotters and modern laser direct imaging (LDI) systems, reaffirming its position as the industry standard for PCB production documentation.

The exact procedure depends on the CAD platform used. Below are examples for common tools.

1. KiCad

In KiCad 7, generating Gerber and drill files involves the following steps:

1. Run a design check – perform a DRC (Design Rule Check) before export.
2. Select layers – choose all layers required for fabrication, such as F.Cu, B.Cu, solder mask layers, and silkscreen.
3. Adjust Gerber settings – enable options such as Plot reference designators, Subtract solder mask from silkscreen, and the recommended Protel file extensions.
4. Generate files – click Plot, then generate drill files (Generate Drill Files) and, optionally, a drill map.
5. Verify output – review the exported files in a Gerber viewer to ensure that board outline, holes, and layers are correctly represented.
6. Compress files – package all output files into a single .zip archive before submitting them to the manufacturer.

2. Altium Designer

1. Create a new OutJob file and select the required manufacturing outputs.
2. Choose the desired layers and the RS-274X or Gerber X2 format.
3. Configure export parameters, including units, templates, and layer sets.
4. Click Generate and verify the resulting files.

3. Autodesk Eagle

1. Confirm correct placement of silkscreen on the top and bottom layers.
2. Open the CAM Processor and export Gerber files from the .brd file.
3. Configure layer visibility and drilling options.
4. Validate the generated output and compress the files into a .zip archive before submission.

Gerber files are not delivered as a single document but as a collection of separate files, each representing a specific layer of the PCB design. The function of each layer is defined by its file extension. For instance, GTL refers to the top copper layer, GBL to the bottom copper layer, GTS and GBS to the solder mask layers, while GTO and GBO denote the silkscreen layers. Drilling information is typically stored in TXT or DRL files, and the GBX extension may appear in more advanced designs where a layer contains data that does not clearly fall into standard categories.

Although most CAD tools follow similar naming conventions, designers should always verify that the manufacturer understands the meaning assigned to each layer. Every file is processed by the CAM system, and any incorrect layer assignment can result in severe production errors that cannot be corrected once manufacturing begins.

Gerber file verification is a critical step before releasing a design for production, as it allows for the detection of errors that could halt the manufacturing process or lead to defective PCBs. The objective of this review is to confirm that all layers are complete, correctly named, and properly associated with their respective extensions, and that they contain all the data required for solder mask, silkscreen, drilling, and assembly operations. It is equally important to ensure that the file format complies with the manufacturer’s specifications so that CAM systems can interpret the data without ambiguity.

Verification is performed using dedicated Gerber viewer software—such as Gerbv, CAM350, or Ucamco Gerber Viewer—which enables visual inspection of each layer and detailed analysis of the board’s geometry. These tools help identify discrepancies such as incorrectly assigned paste layers, missing solder mask data, or improper hole alignment. Proper verification prior to submission eliminates issues that could later result in material waste, production delays, or the need to restart the manufacturing process.

Gerber files ensure that PCB manufacturers can accurately reproduce a design, prepare tooling for fabrication and assembly, and perform quality checks. Despite continuous advancements in electronic design and manufacturing technologies, Gerber remains the principal format for exchanging PCB production data – fully compatible with traditional laser plotters, LDI machines, and modern direct imaging solutions.

A thorough understanding of how to generate and validate Gerber files is essential for PCB designers, as it helps prevent manufacturing errors and supports the delivery of high-quality, reliable boards.