What is a gerber file and how to get one?

Gerber files are the most common and most widely used file formats in the electronics assembly industry. This is the type of files that most circuit design softwares produce. In the electronics assembly industry, they are often called stencil data. In PCB manufacturing, they can also be referred to as light painting files. They are very versatile.  


The Gerber file is a standard format defined by the EIA with two different types: RS274-D and RS274-X. RS274-X is an extension file of the RS274-D. If possible, production and manufacturing designers should use RS274-X and require their supporting teams to do the same. Using this extension format is conducive to the production preparation of each process.


Gerber output is a key step in the process of transforming Layout engineers' design efforts into a real PCB board. Hence, careful inspection is essential. If the design is inconsistent with the actual product, it will not yield a good result. 

The first step is knowing how to create these files with your software. The following describes several commonly used PCB software titles which can export Gerber layer descriptions. This should help you to know which layers are necessary for your PCBA production.



The Gerber file must contain GBL, GTL, GBO, GTO, GBS, GTS, GKO/GMX with the drill data layer generated. DRR (specified drill type) and .TXT file (specify the location of each hole and the required Drill), requires 8+x layers, where x is the number of intermediate signal layers. For example, if your PCB is double-sided, then X=0 and GTP is extracted. GBP will be used as the steel mesh file. 

.GTL - Top (copper) Layer

.GBL - Bottom (copper) Layer 

.G1, .G2, ... , - Mid Layer 1, 2, ... , 30 

.GP1, .GP2, ... , - Internal Plane Layer 1, 2, ... , 16 

.GTO - Top Overlay

.GBO - Bottom Overlay 

.GTP - Top Paste Mask 

.GBP - Bottom Paste Mask 

.GTS - Top Solder Mask 

.GBS - Bottom Solder Mask 

.GKO - Keep-Out Layer 


Cadence Allegro

The Gerber file must contain all levels of the exported .art file, the exported .drl file, the exported .rou file, and the extracted GTP. GBP is the steel web file.

1. nc parameter text:  nc_param.txt 

2. Aperture and artwork format:  art_aper.txt 

3. Aperture parameter text:  art_param.txt Aperture parameter text

4. Top(comp.)side artwork:  top.art

5.Bottom(solder) side artwork: bot.art 

6. Top(comp.)side silkscreen artwork: topsilk.art 

7. Bottom(solder) side silkscreen artwork:botsilk.art 

8.Top(comp.) side solder mask artwork: topsold.art 

9. Bottom(solder) side solder mask artwork  botsold.art 

10. Drilling and dimension files: drill.drl

11.  Drill tape file:  ncdrill1.rou

(if elliptical hole or rectangle hole on PCB required)



Gerber needs to include the following layers, extracting GTP and GBP as the steel mesh layers:

GTL - TopLayer Top

GBL - BottomLayer ground floor

GTS - SolderMaskTop Top Solder Mask

GBS - SolderMaskBottom Bottom Solder Mask

GTO - SilkScreenTop Top Silk Screen

GBO - SilkScreenBot bottom layer silk screen

GKO - BoardOutline Frame

TXT Drill Plated hole coordinate file



Gerber needs to include the following layers, extracting F.paste and B.paste as the steel mesh layers:

F.CU.gbr - TopLayer Top

B.CU.gbr - BottomLayer Bottom

F.Mask.gbr - SolderMaskTop top solder mask

B.Mask.gbr - SolderMaskBottom Bottom Solder Mask

F.SilkS - SilkScreenTop top silk screen

B.SilkS - BoardOutline bottom layer silk screen

Edge.cut.gbr - border

.drl- Drill Platedhole coordinate file


There are many other software products that can also export these files. Need some help in these areas of your production? Feel free to contact us and our team of experienced layout engineers will be delighted to help!

Posted by Chen Lei

Chen Lei

Having majored in automation engineering, Chen Lei previously worked on analog devices manufacturing and electronics design. He's now one of our electronics design experts at NexPCB, bringing IoT innovations to life one board at a time. In his free time, Chen likes to disassemble electronics gadgets to see how they were manufactured.