PCB Gerber Files: Ultimate Guide for Beginners.

RS-274-D is the first Gerber file format developed by Gerber Scientific Products in the 1960s. It is a binary file format that represents PCB design information as a set of commands, each command comprising a specific instruction and data for that instruction. RS-274-D is still in use today, though with the introduction of more advanced Gerber formats like Gerber-X2, it is less common.

The format is based on a matrix of “dots” or “pels” (picture elements), which describes the geometries of the PCB. Each pel is defined by a location within the matrix, and a “state” — either “on” or “off”. The pels are arranged in a rectangular grid, with the first pel located at the origin (0, 0). The X and Y coordinates of each pel are encoded in ASCII, in thousandths of an inch or millimeter.
RS-274-D is divided into two main sections: the aperture list and the drawing list. The aperture list contains definitions of the “tools” used to create the circuits, while the drawing list specifies the actual data to be drawn using those tools.
The aperture list contains the definitions of the aperture shapes, sizes, and features used to draw the PCB. The aperture list uses a series of commands to define the size and shape of each aperture, followed by a description of the actual data that will be drawn using that aperture. The aperture list also includes commands to define the units of measurement used for the data.

The drawing list specifies the actual data to be drawn using the tools defined in the aperture list. The data is represented as a series of commands, each starting with an X and Y coordinate and followed by a command code. The command code determines what type of object is being drawn, with codes for lines, arcs, circles, and other shapes.
Despite its limitations, RS-274-D is still used in some cases, particularly for simple PCB designs. However, more advanced Gerber formats like Gerber-X2 have largely replaced it due to their improved functionality and ease of use.

RS-274-X is an improved version of the RS-274-D Gerber file format. It was introduced in the 1980s as a replacement for RS-274-D, and added support for aperture definitions, allowing for more complex geometries. The format was developed to provide a standardized way to communicate PCB designs to manufacturing facilities.

The RS-274-X format’s crucial aspect is its capability to specify apertures.An aperture is a tool used to create shapes on a PCB, such as a circle or a rectangle. In RS-274-X, aperture definitions are included within the data file and use a syntax similar to the drawing commands. An aperture consists of either a simple shape defined by its size or a more complex shape defined by a custom “macro”.
Another improvement in RS-274-X is the use of ASCII characters in place of the binary data used in RS-274-D. This made it easier for PCB designers to view and edit files using common text editors. The new format also allowed designers to include comments in the data file, making it easier to understand the intention behind their designs.
RS-274-X has several commands that help to describe the PCB layout in more detail. For example, G01 is a command used to draw a line, while G02 and G03 are used to draw arcs. D codes specify the aperture to be used for each segment. A D code is a two-digit number that corresponds to an aperture definition in the aperture list.

Overall, RS-274-X improved upon the limitations of the previous RS-274-D format and became the industry standard for Gerber file formats for many years. However, as PCB design software has continued to evolve, newer file formats like Extended Gerber (XGerber) and Gerber-X2 have been developed to meet the needs of more complex PCBs.

Extended Gerber (XGerber) is a Gerber file format that was developed to extend the capability of the original Gerber format (RS-274-D). It was created to address some of the limitations of the RS-274-D format and provide additional features and functionality for PCB designers.

The XGerber format introduces several enhancements over the RS-274-D format, such as support for aperture macros, which allow users to define complex apertures and reuse them throughout the design. The format also includes support for different fill types, allowing designers to control the fill area of polygons or planes in their designs.
Another important feature of the XGerber format is its support for embedded data, which enables designers to include additional information such as drill and rout data directly in the Gerber files. This eliminates the need for separate files and simplifies the fabrication process.

Like the RS-274-D format, the XGerber format consists of a series of commands that describe the geometries of the circuits, with each command containing specific instructions and data for that instruction. The commands are based on a set of Gerber codes, which are standardized by the IPC (Association Connecting Electronics Industries).
Overall, the Extended Gerber (XGerber) format has become widely used in the PCB industry due to its enhanced functionality and compatibility with modern PCB design tools.

Gerber X2 is a newer Gerber file format that was developed to provide an even greater level of functionality and compatibility with modern PCB design tools than the previous Gerber formats. It was introduced to address some of the limitations of the older Gerber formats and provide additional features and capabilities that were not present in those formats.
The Gerber X2 format includes support for multiple layers, embedded aperture information, and various fill types. It also provides the ability to include meta-information, such as PCB layer structure, trace width, and drill sizes, directly in the Gerber files. This eliminates the need for separate documentation and simplifies the manufacturing process.

One of the key features of the Gerber X2 format is its support for metadata tags, which enable designers to include additional information related to the PCB design, such as supplier information, material specifications, and assembly instructions. The format also includes support for the use of XML-based data structures, which allows the information in the Gerber files to be more easily managed and exchanged between different software applications.
Like the previous Gerber formats, the Gerber X2 format consists of a series of commands that describe the geometries of the circuits, with each command containing specific instructions and data for that instruction. The commands are based on a set of standardized codes developed by the IPC (Association Connecting Electronics Industries).

Overall, the Gerber X2 format has gained widespread adoption in the PCB industry due to its enhanced functionality and compatibility with modern PCB design tools. It has become the preferred format for many designers and manufacturers who require accurate and reliable data exchange between different stages of the PCB design and manufacturing process.
In addition to these formats, there are also several vendor-specific Gerber formats that have been developed over the years. However, the industry has largely standardized on the Gerber-X2 format as the preferred format for exchanging PCB design data.