Introduction to Gerber and Gerber X2 Formats

Gerber files are widely used in the electronics industry for manufacturing printed circuit boards (PCBs). They contain essential information about the PCB design, including copper layers, solder mask, silkscreen, and drill data. The Gerber format has evolved over time to meet the growing demands of PCB designers and manufacturers. One of the most significant advancements in the Gerber format is the introduction of Gerber X2, which offers several advantages over the traditional Gerber format.

In this article, we will explore the key differences between Gerber and Gerber X2 files, their benefits, and how they impact the PCB manufacturing process.

What are Gerber Files?

Gerber files, also known as RS-274X files, are a standard format used in the PCB industry to describe the layout and design of a printed circuit board. They are named after the Gerber Scientific Instrument Company, which developed the format in the 1960s. Gerber files are essentially a set of 2D vector images that represent different layers of a PCB, such as copper traces, solder mask, silkscreen, and drill holes.

Each Gerber file corresponds to a specific layer of the PCB and contains information about the geometries, apertures, and coordinates of the elements on that layer. These files are generated by PCB design software and are used by PCB Manufacturers to fabricate the physical board.

Structure of a Gerber File

A typical Gerber file consists of the following components:

1. Aperture List: This section defines the shapes and sizes of the apertures (e.g., circles, rectangles, polygons) used in the file.
2. Coordinate Data: This section contains the X-Y coordinates of the elements on the layer, such as traces, pads, and polygons.
3. D-Codes: These are the codes that refer to the apertures defined in the aperture list. They are used to specify which aperture is being used at a given coordinate.
4. G-Codes: These are the commands that control the plotter’s movement and actions, such as moving to a specific coordinate, exposing or not exposing the film, and ending the file.

Here’s an example of a simple Gerber file:

%FSLAX24Y24*%
%MOMM*%
%ADD10C,0.5*%
D10*
X0Y0D02*
X10000Y0D01*
X10000Y10000D01*
X0Y10000D01*
X0Y0D01*
M02*

In this example:
– %FSLAX24Y24*% specifies the format statement, indicating the coordinate format and resolution.
– %MOMM*% sets the unit to millimeters.
– %ADD10C,0.5*% defines an aperture with D-Code 10, which is a circle with a diameter of 0.5mm.
– D10* selects the aperture with D-Code 10.
– The lines starting with X and Y are the coordinate data, representing a square with 10mm sides.
– D02* and D01* are G-Codes for moving the plotter without exposing and with exposing the film, respectively.
– M02* indicates the end of the file.

What is Gerber X2?

Gerber X2, also known as Extended Gerber, is an enhanced version of the traditional Gerber format. It was introduced in 2014 by Ucamco, the company that now owns and maintains the Gerber format. Gerber X2 builds upon the existing RS-274X standard and adds new features and attributes to improve the clarity, efficiency, and reliability of PCB data transfer.

One of the primary goals of Gerber X2 is to eliminate the need for additional documentation and files by embedding more information directly into the Gerber files. This approach reduces the chances of errors and misinterpretations during the PCB manufacturing process.

Key Features of Gerber X2

1. Embedded Aperture Definitions: In Gerber X2, aperture definitions are embedded directly in the file, eliminating the need for a separate aperture list file. This feature ensures that the aperture information is always associated with the corresponding Gerber file, reducing the risk of errors.

2. Attribute Data: Gerber X2 introduces attribute data, which allows designers to embed additional information about the PCB elements directly in the Gerber file. Attributes can include data such as component references, pad functions, net names, and more. This information helps PCB manufacturers better understand the design intent and catch potential issues early in the manufacturing process.

3. Nested Step and Repeat: Gerber X2 supports nested step and repeat, which allows for more efficient representation of repeated patterns or arrays in the PCB design. This feature can significantly reduce the file size and improve the readability of the Gerber data.

4. Standardized Metadata: Gerber X2 includes standardized metadata that provides essential information about the PCB, such as the PCB Thickness, copper weight, and layer stackup. This metadata helps ensure that the PCB manufacturer has all the necessary information to produce the board accurately.

5. Improved Coordinate Format: Gerber X2 introduces a new coordinate format that supports decimal places, making it easier to represent fine details and complex shapes in the PCB design.

Here’s an example of a Gerber X2 file with embedded aperture definitions and attribute data:

%TF.FileFunction,Copper,L1,Top*%
%TF.Part,Single*%
%FSLAX46Y46*%
%MOMM*%
%ADC$1*%
%ADD10C,0.5*%
%ADD11R,1X2X0.5*%
%SRX1Y1I0.0J0.0*%
G04 #@! TD.AperFunction,NonPlated,SMDPad,CuDef*%
%TA.AperFunction,SMDPad,CuDef*%
D10*
X0Y0D02*
X10000Y0D01*
%TD*%
G04 #@! TO.P,R1,2,RESC1608*%
%TO.P,R1,1*%
%TO.N,Net1*%
%TA.AperFunction,SMDPad,CuDef*%
D11*
X15000Y5000D03*
%TD*%
M02*

In this Gerber X2 example:
– %TF.FileFunction,Copper,L1,Top*% specifies the file function, indicating that this file represents the top copper layer.
– %ADC$1*% starts the aperture definition block.
– %ADD10C,0.5*% and %ADD11R,1X2X0.5*% define the apertures with D-Codes 10 and 11, respectively.
– %SRX1Y1I0.0J0.0*% sets the step and repeat parameters.
– %TA.AperFunction,SMDPad,CuDef*% is an attribute that specifies the aperture function as an SMD pad with a copper definition.
– %TO.P,R1,1*% and %TO.N,Net1*% are attributes that provide information about the component reference and net name associated with the SMD pad.

Advantages of Gerber X2 over Traditional Gerber

Gerber X2 offers several advantages over the traditional Gerber format, making it a preferred choice for modern PCB design and manufacturing:

1. Improved Clarity and Communication: By embedding more information directly into the Gerber files, Gerber X2 enhances the clarity and communication between PCB designers and manufacturers. The additional data helps manufacturers better understand the design intent and catch potential issues early in the process, reducing the risk of errors and delays.

2. Reduced File Count: With Gerber X2, the need for separate aperture list files and other supporting documentation is eliminated. All the necessary information is embedded within the Gerber files themselves, simplifying file management and reducing the chances of missing or mismatched files.

3. Enhanced Design Validation: The standardized metadata and attribute data in Gerber X2 enable more comprehensive design validation. PCB manufacturers can use this information to verify the design against their manufacturing capabilities and constraints, helping to identify and resolve issues before production begins.

4. Improved Efficiency: Features like nested step and repeat and the new coordinate format in Gerber X2 contribute to improved efficiency in PCB data transfer and processing. These enhancements can lead to smaller file sizes, faster data transfer, and more streamlined manufacturing workflows.

5. Future-Proofing: Gerber X2 is designed to accommodate future advancements in PCB technology. The format is extensible, allowing for the addition of new attributes and features as the industry evolves. By adopting Gerber X2, PCB designers and manufacturers can ensure that their data remains compatible with future tools and processes.

Transition from Gerber to Gerber X2

While Gerber X2 offers numerous benefits, the transition from traditional Gerber to Gerber X2 requires some adjustments in the PCB design and manufacturing workflow.

PCB Design Software Support

To create Gerber X2 files, PCB designers need to use design software that supports the Gerber X2 format. Most modern PCB design tools, such as Altium Designer, KiCad, and Eagle, have added support for Gerber X2. However, designers should verify that their software version is compatible with Gerber X2 and that they have the necessary settings and options configured correctly.

PCB Manufacturer Readiness

Not all PCB manufacturers may be fully equipped to handle Gerber X2 files. It is essential to communicate with the chosen manufacturer and ensure that they can process and utilize the additional information provided in Gerber X2 files. Some manufacturers may still prefer traditional Gerber files, so it is crucial to clarify their requirements and capabilities beforehand.

Gradual Adoption

The transition from traditional Gerber to Gerber X2 can be a gradual process. PCB designers and manufacturers can start by incorporating some of the Gerber X2 features, such as embedded aperture definitions and attribute data, while still maintaining compatibility with traditional Gerber workflows. As the industry becomes more familiar with Gerber X2 and its benefits, a full transition can be made.

Frequently Asked Questions (FAQ)

1. Can Gerber X2 files be viewed and edited with traditional Gerber viewers and editors?

2. Many Gerber viewers and editors have been updated to support Gerber X2 files. However, some older tools may not be fully compatible with the new format. It is recommended to use software that explicitly supports Gerber X2 to ensure accurate viewing and editing of the files.

3. Are Gerber X2 files backward compatible with traditional Gerber?

4. Gerber X2 files are not strictly backward compatible with traditional Gerber. While the basic structure and syntax of the files remain similar, the additional features and attributes in Gerber X2 may not be recognized or processed correctly by older tools and systems designed for traditional Gerber.

5. Do PCB manufacturers charge extra for processing Gerber X2 files?

6. In general, PCB manufacturers do not charge extra for processing Gerber X2 files. However, it is always best to check with the specific manufacturer for their pricing and policies regarding Gerber X2.

7. Can I mix traditional Gerber and Gerber X2 files in the same PCB project?

8. While it is technically possible to mix traditional Gerber and Gerber X2 files in the same project, it is not recommended. Mixing formats can lead to confusion and potential errors in the manufacturing process. It is best to use a consistent format, preferably Gerber X2, for all the files associated with a PCB project.

9. Is Gerber X2 the only advanced format for PCB data transfer?

10. Gerber X2 is not the only advanced format for PCB data transfer. Other formats, such as ODB++ and IPC-2581, also offer enhanced features and capabilities. However, Gerber X2 has the advantage of being an extension of the widely-used Gerber format, making it easier for the industry to adopt and transition to.

Conclusion

The introduction of Gerber X2 represents a significant advancement in the way PCB design data is communicated and processed. By embedding more information directly into the Gerber files, Gerber X2 enhances clarity, reduces errors, and improves efficiency in the PCB manufacturing process.

While the transition from traditional Gerber to Gerber X2 may require some adjustments in the design and manufacturing workflow, the benefits of adopting this enhanced format are substantial. As the electronics industry continues to evolve and push the boundaries of PCB technology, Gerber X2 is well-positioned to support these advancements and streamline the PCB design and manufacturing process.

PCB designers and manufacturers alike should explore the capabilities of Gerber X2 and consider incorporating this format into their workflows. By embracing Gerber X2, the industry can take a significant step towards more efficient, accurate, and future-proof PCB data transfer and manufacturing practices.