PCB Fabrication Essential: Gerber File Know-How

One of the best practices employed in creation of PCBs is using Gerber files. Gerber files are used to supplement information and act as a medium of information transfer from the designer to fabricator.

What are Gerber Files?

Gerber files are used in the creation of PCBs. Gerber data is the standard format used by the PCB industry and the files are used to communicate all the design details to the manufacturer. They define the exact locations of the components, circuitry, solder mask, layers, etc. A Gerber file is like a blueprint of the PCB, acting as a guideline for the creation of the PCB. The prevalent format of Gerber files used is RS-274X, which is also known as ‘extended Gerber’. It is widely preferred because it automatically sets up the aperture settings.

Capabilities of Gerber Files

Gerber files communicate all relevant information needed for successful design of the PCB. As such, every meticulous detail has to be mentioned in the files. Gerber files are used for the following reasons:

1. The thickness of the copper traces.
2. The density of the circuitry.
3. The location of components (denoted by X & Y co-ordinates).
4. Number of layers.
5. Core material.
6. Size and shape of the boards.
7. Size of spaces.
8. Location of plated through holes and non-plated through holes.
9. Location of any other interconnectors.
10. Printing of logos, numbers, or any other reference details.
11. Gerber files are used for the final few steps of PCB design as well. They pinpoint the exact locations where the solder mask and silkscreen should be applied.
12. Any other configuration details.

Gerber files are created separately for all the layers of a PCB. Some engineers provide separate Gerber files for every detail. For example, a manufacturer can expect different files for the design of the copper traces on the bottom and top side of the board, location of solder mask on the bottom and top side of the board and so on. A separate file that acts as a guideline for all the Gerber files is provided by the engineer/ designer as well. To elucidate, for a single-layer PCB, up to nine Gerber files can be provided.

Gerber files are useful when creating rigid, rigid-flex or flex PCBs in single, double, or multiple layers. Gerber files are useful in recalling the design at a later date. For prototype designing, a particular copy of the Gerber file will be used. Depending on the shortcomings of the design, the designer will know precisely where the problems exists. He can then make the changes accordingly to the file. The new PCBs can be created according to the modified design. These designs can also be used at a later date to re-create the PCB. It is also a useful tool when repairing or refurbishing the PCBs. Thus, Gerber files are an indispensable part of PCB design and fabrication.