History of Gerber Formats

The Gerber format was originally developed by the Gerber Scientific Instrument Company in the 1960s as a means of controlling their vector photoplotters. These early Gerber Files were used to describe the images (copper layers, solder mask, legend, etc.) in a PCB design.

Over time, the Gerber format evolved to keep pace with advancements in PCB design and manufacturing technology. In 1998, the RS-274X format was introduced, which added support for embedded apertures and improved the overall efficiency of the format.

Evolution of Gerber Formats

Year	Format	Description
1960s	RS-274-D	Original Gerber format
1980s	RS-274-X	Extended Gerber format
1998	RS-274X	Introduced embedded apertures
2014	X2	Attributes added for intelligent data transfer

Gerber File Structure

A Gerber file is a plain text file that contains a sequence of commands and coordinates that describe the layout of a single layer of a PCB. Each Gerber file typically represents one layer of the PCB, such as the top copper layer, bottom copper layer, or solder mask layer.

Example Gerber File

G04 Gerber RS-274X file*
%FSLAX24Y24*%
%MOIN*%
%ADD10C,0.01*%
D10*
X0Y0D02*
X1000000Y0D01*
X1000000Y1000000D01*
X0Y1000000D01*
X0Y0D01*
M02*

In this example:
– G04 is a comment.
– %FSLAX24Y24*% sets the format specification to 2.4 integer format.
– %MOIN*% sets the units to inches.
– %ADD10C,0.01*% defines an aperture with a diameter of 0.01 inches.
– D10* selects the aperture defined in the previous line.
– The X and Y commands draw a square of 1 inch by 1 inch.
– M02* indicates the end of the file.

Gerber File Extensions

Gerber files use different file extensions to represent the various layers in a PCB design. Some common file extensions include:

Extension	Description
.GTO	Top overlay
.GTS	Top solder mask
.GTL	Top layer
.GBL	Bottom layer
.GBS	Bottom solder mask
.GBO	Bottom overlay
.GM1	Mechanical layer 1
.GD1	Drill drawing
.GG1	Global notes

Advantages of Gerber Formats

Gerber formats offer several advantages for PCB design and manufacturing:

1. Universality: Gerber files are widely supported by PCB Design Software and manufacturing equipment, making them a standard for data exchange in the industry.

2. Simplicity: Gerber files are plain text files that are easy to read and interpret by both humans and machines.

3. Precision: Gerber formats support high-precision coordinates, allowing for accurate representation of complex PCB designs.

4. Flexibility: Gerber formats can represent a wide range of PCB FEAtures, including copper traces, solder mask, silkscreen, and drilled holes.

Limitations of Gerber Formats

Despite their widespread use, Gerber formats have some limitations:

1. Lack of intelligent data: Traditional Gerber files do not include information about the PCB design intent, such as component placement or net connectivity. This limitation was addressed with the introduction of the X2 format in 2014.

2. Multiple files: A complete PCB design is typically represented by multiple Gerber files, one for each layer. This can make data management and transfer more complex compared to newer formats like ODB++.

3. Limited support for advanced features: Some advanced PCB design features, such as embedded components or high-density interconnects, may not be easily represented using Gerber formats.

Alternatives to Gerber Formats

While Gerber formats remain the most widely used standard for PCB data exchange, there are some alternatives:

1. ODB++: The ODB++ Format is a more modern alternative to Gerber that includes intelligent data about the PCB design, such as component placement and net connectivity.

2. IPC-2581: The IPC-2581 format is an open standard that aims to provide a single, comprehensive format for PCB design data exchange.

3. STEP: The STEP (Standard for the Exchange of Product Model Data) format is a generic CAD data exchange format that can be used for PCB design, although it is not as widely supported as Gerber in the PCB industry.

Best Practices for Using Gerber Formats

To ensure successful data exchange and PCB manufacturing, consider the following best practices when using Gerber formats:

1. Use the latest format: Use the most recent version of the Gerber format supported by your PCB design software and manufacturing partners. Currently, the X2 format offers the most comprehensive and efficient data exchange.

2. Include all necessary files: Ensure that your Gerber dataset includes all the necessary files for PCB manufacturing, including copper layers, solder mask, silkscreen, and drill files.

3. Verify your Gerber files: Use Gerber viewer software to verify that your Gerber files accurately represent your PCB design before sending them for manufacturing.

4. Communicate with your manufacturing partner: Work closely with your PCB manufacturing partner to ensure that they have all the necessary information and files to produce your PCB design successfully.

FAQ

1. Q: Are Gerber files the same as CAD files?

A: No, Gerber files are not the same as CAD files. CAD files contain the complete PCB design, including components and net information, while Gerber files represent the individual layers of the PCB for manufacturing.

1. Q: Can I view Gerber files without special software?

A: While Gerber files are plain text files, they require special viewer software to display the PCB layout graphically. Many free and commercial Gerber viewer programs are available.

1. Q: What is the difference between RS-274-D and RS-274X Gerber formats?

A: RS-274-D is the original Gerber format, while RS-274X is an extended version that supports more efficient data representation and embedded aperture definitions.

1. Q: How do I know which Gerber file represents which layer of my PCB?

A: Gerber files use standardized file extensions to represent the different layers of a PCB, such as .GTL for the top copper layer or .GBS for the bottom solder mask layer.

1. Q: Can I use Gerber files for PCB design, or are they only for manufacturing?

A: Gerber files are primarily used for data exchange between PCB design software and manufacturing equipment. While some PCB design software can import Gerber files, they are not typically used for the actual design process.

Conclusion

Gerber formats have been the backbone of PCB design and manufacturing data exchange for decades. By providing a simple, precise, and universal method for representing PCB layouts, Gerber files have enabled the rapid growth and advancement of the electronics industry.

As PCB designs continue to become more complex and sophisticated, the Gerber format has evolved to keep pace, with the introduction of the X2 format offering intelligent data exchange and improved efficiency.

Despite the emergence of alternative formats like ODB++ and IPC-2581, Gerber remains the most widely supported and adopted standard in the PCB industry. By understanding the structure, advantages, and best practices for using Gerber formats, PCB designers and manufacturers can ensure successful collaboration and high-quality PCB Production.