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What is Gerber and How to Generate Gerber File - Steps with Images

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Wed, Jan 06, 2021

Gerber files are necessary to require printed circuit boards (PCB). When you draw the schematics, you need to generate them into Gerber files so that PCB manufacturers can follow your requirements.

You may ask, what is a Gerber file?

More importantly, how to generate Gerber files?

No worries, this post will let you know what is Gerberhow to generate it, and how to print PCB from the Gerber file.

Part 1: What is a Gerber File

The Gerber format is an open 2D binary vector image file format. A Gerber file is the standard file used by printed circuit board industry software to describe the PCB images such as copper layers, solder mask, legend, etc.

Each layer of the PCB needs a Gerber file. You can know the layers of the PCB here.

When you generate Gerber files for either a single-layer or a multilayer PCB, multiple Gerber files are saved at once in a RAR or ZIP file.

Gerber Files by Type and Format

The trick with Gerbers is that every file you generate will be associated with a particular layer on your board layout, each with its own unique file extension. 

File Extension of PCB Layer on Autodesk EAGLE

File Extension
PCB Layer
.cmp
Top Copper
.sol
Bottom Copper
.stc
Top Soldermask
sts
Bottom Soldermask
.plc
Top Silkscreen
.pls
Bottom Silkscreen

File Extension of PCB Layer on Altium Designer

File Extension
PCB Layer
.GTO
Top Overlay
.GTP
Top Paste
.GTP1
Top Paste
.GTS1
Top Solder
.GTS
Top Solder
.GTL
Top Layer
Top Layer
<2-11
.G1
Mid-Layer 1
.G2
Mid-Layer 2
.GBL
Bottom Layer
.GBS
Bottom Solder
.GBP
Bottom Paste
.GBO
Bottom Overlay
.GM1
Mechanical 1
.GM7
Mechanical 7
.GM13
Mechanical 13
.GM15
Mechanical 15
.GM16
Mechanical 16
.GKO
Keep-Out Layer
.GPT
Top Pad Master
.GPB
Bottom Pad Master

Another thing to remember about Gerber’s is their available formats – Gerber RS-274D and Gerber RS-274X. The D format is the older standard and uses two files per layer on your PCB. The newer X standard has done away with the two file format and contains all of the information about a layer in a single file.

Regarding having to manage your design data, the X format makes it a whole lot easier when you only have to keep track of one file per layer instead of two. We’d always recommend using the Gerber RS-274X format.

Now you’ve got to know that once you generate Gerber files, you can get the PCB printed from them. Let’s dive to see how to generate Gerber files using OrCAD and Altium!

Part 2: Generating Gerber Files Using OrCAD

Step 1. First of all, design PCB on any OrCAD software (like in the figure below ). To learn more about PCB layout, read here. Verify all points to check those are not shorted. After verification, move to the next step.

design pcb

Step 2. Navigate to the " Output" option on the top tab of the software.

output gerber orcad

Step 3. After clicking on " Output", choose " Generate Gerber".

gerber file orcad

Step 4. Click on " Output to a single ZIP file", and then go to " Reflection" > " Mirror". Confirm to generate a Gerber file by clicking on " OK".

confirm gerber orcad

Step 5. Finally, the Gerber file in ZIP format is generated. It can be found in your saved location.

save gerber orcad

Part 3: Generating Gerber Files Using Altium

Step 1. Open your schematic using Altium Designer. Navigate to the " File" option on the top tab of the software and go to " Fabrication Outputs" > " Gerber Files".

generate gerber altium

Step 2. You will jump to the Gerber Setup window. Here, you need to choose the " Layers" option on the top tab.

Step 3. Then click " Plot Layers" > " All on". Confirm to generate the Gerber file by clicking the " OK" button.

confirm gerber altium

If you want to generate the drill file, follow the steps below.

Step 1. Open the schematic using Altium. Navigate to the " File" option on top of the tap.

Step 2. Choose "Fabrication Outputs" and click " NC Drill Files" from the drop-down list.

generate drill file altium

Step 3. The NC Drill Setup window is open. Click " OK" and you generate the drill file.

confirm-drill-file-altium.jpg

Note
The drill file and Gerber file are generated separately. But you need to place them into the same RAR or ZIP file before uploading the file on a PCB printing website.

Applications of Gerber Files

As mentioned above, a Gerber file is a 2D binary vector image file format to describe the circuit board image. It was widely used to drive vector plotters. Details Expand in this Standard Gerber - Standard Gerber was a numerical control (NC) format designed by Gerber Systems Corp to drive their vector photo plotters for the PCB industry in the 1960s and 1970s. It was a subset of the Electronic Industries Association RS-274-D specification, a format to drive mechanical NC machines in a wide range of industries.