What Are Gerber Files?
Gerber files are the industry-standard format used by PCB manufacturers to produce boards precisely according to design specifications. They provide detailed two-dimensional representations of each PCB layer, including copper traces, pads, vias, solder mask, legend, and more.
As a universal format, Gerber files communicate exactly how a machine should fabricate the board. They form the foundation of the PCB fabrication process and are widely accepted by manufacturers and designers alike.
Many leading PCB manufacturers, such as JLCPCB—which offers 1-4 layer PCBs starting at $2—exclusively support Gerber files in RS-274X format. This includes files for copper layers, solder mask, legend, mechanical, and SMD paste layers.
How Gerber Files Drive PCB Manufacturing
Modern PCB production has evolved dramatically. Early processes relied on vector photo plotters to create tooling films, where light exposed patterns for pads and traces through limited apertures. Designers had to optimize designs around these constraints.
Today's raster laser plotters have replaced them, dramatically reducing plot times from hours to minutes. Gerber files originated to instruct these vector plotters with minimal setup data, X/Y coordinates, draw orders, and aperture selections.
Over time, Gerber formats have incorporated more data like scaling and aperture definitions. Laser plotters rasterize these files to direct the laser in exposing films—aperture info defines trace widths and pad sizes, while draw commands specify lines, fills, or flashes.
Advancements continue: direct laser imaging skips films entirely, etching images straight onto copper. Emerging formats add netlist data for enhanced accuracy. Yet, standard Gerber files remain dominant in fabrication workflows.
Generating Gerber Files from Your PCB Design
After finalizing and verifying your design, export Gerber files tailored to your manufacturer's requirements. Most modern PCB CAD tools, like Altium or KiCad, streamline this with built-in generators.
Typically, create one file per layer: copper signals and planes (e.g., six files for a 4-signal/2-plane stackup), plus separate top/bottom solder mask, silkscreen (if used), and paste layers. Some fabs request additional mechanical or drill map layers.
Configure units, formats, and polarities to match your design and fab specs. Alongside Gerbers, generate an NC Drill file specifying hole sizes and locations for drilling machines—similar in structure but focused on vias and pads.
Conclusion
To ensure flawless results, package Gerbers, NC Drills, fab/assembly drawings, pick-and-place files, BOM, netlists, and a readme. Collaborate early with your contract manufacturer to confirm exact needs and avoid costly revisions.
