What is Gerber File – An Ultimate Guide for Beginners

What is Gerber File – An Ultimate Guide for Beginners

6 September 2023 0 By Anshul Pal

Sometimes you have a question about how we made PCB and what is the process behind this. The creation of a printed circuit board (PCB) is a crucial step in developing electronic products. This complex process requires designers and manufacturers to work closely together. And to ensure the final product functions flawlessly and meets all the necessary standards. Every part and pathway on your PCB design will eventually be made. How do you turn your design data from your CAD system into instructions for making it? It’s straightforward: you create output files in a suitable format. Nowadays, you have various choices for the types of files you can make for your design, but most often, you’ll use the Gerber file format. Other options include ODB++ and IPC-2581.

What is a Gerber File?

Gerber files are like detailed maps for your PCB design. They’re text files that describe all the different parts of your circuit board, such as copper pathways, connection points, protective layers, and labels. These files use codes and coordinates to represent these parts. PCB manufacturers use these files to turn your design into a real circuit board.

Your PCB design software usually creates Gerber files, but the process varies between different software. Most modern Gerber files follow the RS-274X format, which is an updated version of the older RS-274-D standard. hese files save as text, and even though they don’t need a particular name, people often give them extensions like .gb or .gbr.
Gerber files should be inside a .rar or.zip archive with standard file extensions:
Extension                       Layer

  • pcbname.GTL                 Top Copper
  • pcbname.GTS                 Top Soldermask
  • pcbname.GTO                 Top Silkscreen
  • pcbname.GBL                 Bottom copper
  • pcbname.GBS                 Bottom Soldermask:
  • pcbname.GBO                 Bottom Silkscreen:
  • pcbname.TXT                  Drills
  • pcbname.GML/GKO        *Board Outline:
  • 4 layer board also need
  • pcbname.GL2                   Inner Layer2
  • pcbname.GL3                   Inner Layer3

Notes: Gerber file must be RS-274X format.  Drill file(pcbname.TXT) should be Excellon format.

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Data in Gerber File

Now, let’s explore some instances of information found in Gerber files. When you open Gerber data in a text editor, you can view the ASCII data within the file and make adjustments as needed. Some manufacturers may manually make changes to address certain design issues and then confirm these alterations using a Gerber viewer. Below, you’ll find a snippet from a Gerber file (in RS-274-X format) depicting the top overlay layer in a PCB layout.

Gerber File

To generate this output, I used the panel drawing from Mark Harris’s USB Isolator project and exported the top overlay layer.

In this sample Gerber file, there are some elements that can be understood by humans to some extent (like the Altium Designer tag in the header). However, most of the content is not intended for human reading. If you’re determined, you could refer to the Ucamco Gerber file format guidelines to decipher and comprehend each of these entries.

How Gerber File Used In PCB Manufacturing

PCB manufacturing technology has evolved a lot in recent decades. In the past, we used vector photoplotters to make film for PCBs. These machines used focused light through tiny holes to create patterns for pads and traces on the film. We had limited hole options, so designers had to be creative.

Now, we use newer laser plotters that work faster. They use Gerber files to get instructions. Gerber files originally had basic plotter info, coordinates, and commands. Over time, they got more features like macros and aperture definitions.

Today’s laser plotters still use Gerber info, but they’re not limited like the old ones. They turn Gerber data into a raster file, which tells the laser how, where, and what to create on the film. For example, aperture definitions specify trace and pad sizes, and commands say if we need lines, fills, or flashes.

But things keep changing. Some PCB makers now use lasers to create PCB images right on the copper, skipping film. New database formats include more design data like net connections. Gerber files will stick around for a while, so it’s important to know how they fit into PCB manufacturing.

More about PCb’s Formatshttps://en.wikipedia.org/wiki/Gerber_format

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