Gerber is a vector-based manufacturing file format used in PCB fabrication workflows. Gerber files define the geometric data required to manufacture printed circuit boards, including copper traces, solder masks, silkscreens, and board outlines.
Gerber is the most widely used PCB manufacturing interchange format in the electronics industry.
The format is commonly generated by PCB design software such as KiCad, Altium Designer, and EAGLE.
What Is Gerber?
Gerber is a 2D vector manufacturing format used to describe PCB fabrication layers.
Each Gerber file typically represents a single PCB layer, such as:
- top copper
- bottom copper
- solder mask
- silkscreen
- paste layer
- board outline
PCB manufacturers combine multiple Gerber layers to fabricate the final board.
History of Gerber
The Gerber format originated from photoplotting systems used in PCB manufacturing.
Originally developed for vector photoplotters, the format later evolved into a standardized digital manufacturing language for modern PCB fabrication systems.
The modern standard is commonly referred to as RS-274X.
Gerber in PCB Manufacturing
Gerber files are central to PCB manufacturing workflows.
A typical PCB production workflow includes:
- Creating a schematic
- Designing the PCB layout
- Routing copper traces
- Exporting Gerber files
- Exporting Excellon drill files
- Sending fabrication data to the manufacturer
Manufacturers use Gerber data to generate production tooling and photolithography operations.
Gerber Layer Types
PCB designs commonly generate multiple Gerber files.
Typical layer types include:
| Layer | Purpose |
|---|---|
| Top copper | Upper electrical traces |
| Bottom copper | Lower electrical traces |
| Solder mask | Protective coating openings |
| Silkscreen | Printed labels and markings |
| Paste layer | Solder paste stencil geometry |
| Board outline | Physical PCB shape |
Each layer contains different manufacturing information.
Gerber Geometry
Gerber files define geometry using vector-based instructions.
Common geometry elements include:
- lines
- arcs
- flashes
- apertures
- polygons
- filled regions
These structures define conductive and non-conductive PCB areas.
Apertures in Gerber
An aperture defines the drawing tool shape used to generate PCB geometry.
Apertures may represent:
- circular pads
- rectangular pads
- traces
- thermal reliefs
- custom shapes
Modern Gerber formats embed aperture definitions directly within the file.
Gerber and Excellon Files
Gerber and Excellon files are commonly generated together.
| Format | Purpose |
|---|---|
| Gerber | PCB layer geometry |
| Excellon | Drill hole instructions |
Gerber defines graphical manufacturing layers, while Excellon defines drilling operations.
Gerber and PCB Assembly
Gerber data is also used during PCB assembly workflows.
Manufacturing processes may use Gerber layers for:
- solder stencil generation
- inspection alignment
- assembly verification
- component placement referencing
Additional assembly files such as BOM and pick-and-place data are often generated alongside Gerber exports.
Gerber File Extensions
Gerber files may use many different extensions depending on the PCB layer type.
Common examples include:
| Extension | Typical layer |
|---|---|
.gbr | Generic Gerber layer |
.gtl | Top copper |
.gbl | Bottom copper |
.gts | Top solder mask |
.gto | Top silkscreen |
.gko | Board outline |
File naming conventions may vary between PCB software systems.
Gerber in CNC PCB Manufacturing
Gerber files may also be used in CNC-based PCB workflows.
Applications include:
- PCB milling
- engraving isolation routing
- drilling
- solder stencil cutting
CAM software converts Gerber geometry into machine instructions such as G-code.
Gerber vs DXF
Gerber and DXF are both vector-based formats but serve different purposes.
| Format | Primary use | Industry |
|---|---|---|
| Gerber | PCB manufacturing | Electronics |
| DXF | General CAD exchange | Engineering |
Gerber is specialized for electronics manufacturing workflows, while DXF is more general-purpose.
Gerber Precision
PCB manufacturing requires very high geometric precision.
Important fabrication considerations include:
- trace width
- pad dimensions
- hole alignment
- copper clearance
- manufacturing tolerances
Improper Gerber export settings may produce electrically incorrect boards.
Advantages of Gerber
Gerber offers several important advantages.
- industry-standard PCB compatibility
- precise vector geometry
- broad manufacturer support
- efficient layer separation
- compact file structure
- mature manufacturing ecosystem
These characteristics make Gerber the dominant PCB manufacturing format.
Limitations of Gerber
Gerber also has several limitations.
- limited high-level design metadata
- no direct schematic information
- separate drill-file dependency
- limited parametric editing
- weak support for modern 3D assembly data
Modern PCB workflows increasingly combine Gerber with richer manufacturing metadata systems.
Common Software Supporting Gerber
| Software | Gerber support type | Typical use |
|---|---|---|
| KiCad | Native export | PCB design |
| Altium Designer | Native export | Industrial PCB workflows |
| EAGLE | Native export | Electronics prototyping |
| EasyEDA | Native export | Browser-based PCB design |
| FlatCAM | CAM processing | CNC PCB manufacturing |
Gerber Viewing and Verification
Gerber files are commonly inspected before manufacturing.
Verification processes may include:
- layer alignment checks
- drill verification
- copper clearance inspection
- design-rule validation
- manufacturing preview rendering
Gerber viewers help identify fabrication errors before production.