Extend Extended Gerber – Gerber X2

Introduction to Gerber X2

Gerber X2 is an extended version of the Gerber file format, which is widely used in the printed circuit board (PCB) industry for data exchange between PCB design software and manufacturing equipment. The Gerber file format has been the de facto standard for PCB Fabrication data transfer for decades, and Gerber X2 builds upon this foundation to provide enhanced features and capabilities.

What is Gerber X2?

Gerber X2 is an extension of the Gerber file format that includes additional metadata and attributes to convey more information about the PCB design. This metadata includes:

Layer types and functions
Pad and via functions
Net names and classes
Part numbers and reference designators
Fabrication and assembly notes

By including this additional information directly in the Gerber files, Gerber X2 streamlines the PCB fabrication process and reduces the potential for errors and misinterpretations.

Benefits of Gerber X2

The adoption of Gerber X2 offers several benefits to the PCB industry:

Improved communication: Gerber X2 provides a standardized way to convey design intent and manufacturing requirements, reducing the need for additional documentation and clarification.
Fewer errors: With more information embedded in the Gerber files, there is less room for interpretation and fewer opportunities for errors in the manufacturing process.
Faster turnaround times: Gerber X2 enables a more automated and streamlined PCB fabrication process, resulting in faster turnaround times and reduced lead times.
Cost savings: By reducing errors and streamlining the manufacturing process, Gerber X2 can help lower production costs and minimize the need for rework or scrap.

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Gerber X2 File Structure

A Gerber X2 file consists of two main sections: the header and the data block. The header contains metadata and attributes that describe the PCB design, while the data block contains the graphical objects and apertures that define the physical layout of the PCB.

Header Section

The header section of a Gerber X2 file begins with the %TF (File Attribute) command, followed by a series of attribute commands that provide metadata about the PCB design. Some of the most common attribute commands include:

%TF.GenerationSoftware: Specifies the software used to generate the Gerber files.
%TF.CreationDate: Indicates the date and time the Gerber files were created.
%TF.ProjectId: Provides a unique identifier for the PCB project.
%TF.FileFunction: Specifies the function of the file, such as copper layer, solder mask, or drill data.
%TF.FilePolarity: Indicates the polarity of the file (positive or negative).

Data Block Section

The data block section of a Gerber X2 file contains the graphical objects and apertures that define the physical layout of the PCB. This section begins with the %FSLAX command, which specifies the format and coordinate system used in the file.

The graphical objects in the data block are represented using a combination of G-code commands and aperture definitions. Some common G-code commands include:

G01: Linear interpolation (draw a line)
G02: Clockwise circular interpolation (draw an arc)
G03: Counterclockwise circular interpolation (draw an arc)
G04: Comment or delay
G36: Begin region fill
G37: End region fill

Apertures are defined using the %AD command, followed by the aperture type (e.g., C for circles, R for rectangles) and parameters (e.g., diameter, width, height).

Gerber X2 Attributes

One of the key features of Gerber X2 is the ability to include additional attributes that provide more information about the PCB design. These attributes are defined using the %TA command, followed by the attribute name and value.

Some common Gerber X2 attributes include:

.FileFunction: Specifies the function of the file (e.g., Copper, Soldermask, Legend).
.FilePolarity: Indicates the polarity of the file (Positive or Negative).
.Part: Specifies the part number or reference designator associated with a component.
.Net: Indicates the net name associated with a copper feature.
.Component: Provides information about a component, such as its part number or reference designator.
.Pin: Specifies the pin number or function of a component pad.
.Drill: Indicates the type of drill hole (e.g., Plated, NonPlated, Via).

These attributes can be applied to specific graphical objects or apertures in the data block using the %TO (Attribute Override) command.

Creating Gerber X2 Files

Most modern PCB design software packages support the generation of Gerber X2 files. To create Gerber X2 files from your PCB design, you’ll typically need to configure your output settings to include the desired attributes and metadata.

Here are some general steps to create Gerber X2 files:

Complete your PCB design, ensuring that all layers, components, and nets are properly defined.
Open your PCB design software’s Gerber output or file generation settings.
Select the Gerber X2 format as your output format.
Configure the desired attributes and metadata to include in your Gerber X2 files. This may include specifying the file function, polarity, and other relevant information.
Generate the Gerber X2 files, which will typically include a separate file for each copper layer, solder mask, silkscreen, and drill data.
Review the generated Gerber X2 files to ensure that all necessary information is included and that the files are formatted correctly.

It’s important to consult your specific PCB design software’s documentation for detailed instructions on generating Gerber X2 files, as the process may vary slightly between different software packages.

Gerber X2 vs. ODB++

While Gerber X2 is a widely adopted standard for PCB fabrication data exchange, it’s not the only format available. Another popular format is ODB++ (Open Database++), which was developed by Mentor Graphics (now part of Siemens EDA).

ODB++ is a more comprehensive and intelligent format that includes not only the PCB Layout data but also the bill of materials (BOM), component placement information, and other design data. This allows for a more complete and automated PCB fabrication and assembly process.

However, Gerber X2 remains a popular choice for many PCB designers and manufacturers due to its simplicity, compatibility with existing equipment and software, and wide adoption in the industry.

Frequently Asked Questions (FAQ)

Q: Is Gerber X2 backward compatible with older Gerber formats?
A: Yes, Gerber X2 is backward compatible with older Gerber formats. Gerber X2 files can be read and processed by software and equipment that support the older Gerber RS-274X format.
Q: Do I need special software to create Gerber X2 files?
A: Most modern PCB design software packages support the generation of Gerber X2 files. However, you may need to ensure that your software is up to date and that you have configured the output settings correctly.
Q: Can Gerber X2 files be used for PCB Assembly?
A: While Gerber X2 files contain some information relevant to PCB assembly, such as component reference designators and part numbers, they are primarily used for PCB fabrication. For PCB assembly, additional files such as pick-and-place and bill of materials (BOM) are typically required.
Q: Are Gerber X2 files human-readable?
A: Gerber X2 files are text-based and can be opened with a text editor, but they are not easily human-readable due to the use of G-code commands and aperture definitions. Specialized Gerber Viewer software is recommended for inspecting and analyzing Gerber X2 files.
Q: What are the file extensions for Gerber X2 files?
A: Gerber X2 files typically use the same file extensions as older Gerber formats, such as .gbr, .gto, or .top for copper layers, .gbs or .smt for solder mask, and .gbo or .oln for silkscreen. The specific file extensions may vary depending on the PCB design software and the fabricator’s requirements.

Conclusion

Gerber X2 is an important development in the PCB industry, providing a standardized and efficient way to exchange PCB fabrication data. By including additional metadata and attributes directly in the Gerber files, Gerber X2 helps streamline the manufacturing process, reduce errors, and improve communication between PCB designers and fabricators.

As the adoption of Gerber X2 continues to grow, PCB designers and manufacturers can benefit from faster turnaround times, lower production costs, and improved overall quality. While alternative formats like ODB++ offer additional capabilities, Gerber X2 remains a widely supported and accessible standard for PCB fabrication data exchange.

Code Examples

Example 1: Gerber X2 Header

Here is an example of a Gerber X2 file header with some common attributes:

%TF.GenerationSoftware,ExampleCAD,1.0.0*%
%TF.CreationDate,2023-04-15T09:30:00*%
%TF.ProjectId,1234*%
%TF.FileFunction,Copper,L1,Top*%
%TF.FilePolarity,Positive*%

Example 2: Gerber X2 Aperture and Attribute Definitions

This example shows the definition of a circular aperture and the assignment of attributes to a flash command:

%AD10C,0.5*%
D10*
%TO.Part,REF=C1*%
%TO.Net,A00*%
X1000Y1000D02*
X1000Y1500D01*
X1500Y1500D01*
X1500Y1000D01*
X1000Y1000D01*
%TD*%

In this example, a circular aperture with a diameter of 0.5 units is defined using the %AD command. The %TO command is used to assign the .Part and .Net attributes to the subsequent flash commands. The %TD command ends the attribute override.

Example 3: Gerber X2 Region Fill

Here is an example of a region fill in Gerber X2:

G36*
X1000Y1000D02*
X1000Y2000D01*
X2000Y2000D01*
X2000Y1000D01*
X1000Y1000D01*
G37*

In this example, the G36 command begins the region fill, and the G37 command ends it. The region is defined by a series of linear interpolation commands (D01) that outline the boundary of the filled area.

Useful Resources

Ucamco Gerber X2 Specification
Gerber 101: A Gerber File Tutorial
PCB Design Tutorial: Gerber Files and How to Export Them
Gerber X2: The New Standard for PCB Fabrication Data
IPC-2581: A New Standard for PCB Design Data Exchange

These resources provide additional information, tutorials, and specifications related to Gerber X2 and other PCB fabrication data formats.