1. Altium Gerber Files
RS-274-X Gerber file format is a defacto data sharing standard for PCB manufacturing. This is basically a printer or plotter language which is used for PCB CAM (Computer Aided Manufacturing) data generation. Almost everyone who uses Altium Designer software for PCB design, either hobbyist or commercial designer, may have used this feature. It is actually a 2D ASCII file format.
Gerber file format is evolved from applications where it is used to re-create images or graphics i.e., printers and plotters industry. In the same way it is used in electronics hardware industry to print PCB tracks, vias, pads, text, holes, clearances and all information which is contained in a *.PcbDoc design file. The Altium Designer software tool has a feature to create and gerbtool option to verify data as well.
Like other softwares outputs the Altium Designer gerber file can be divided into four subparts:
- Configuration Parameters
- Aperture Definitions
- Drawing Commands
- X/Y Coordinates
Each file extension denotes a specific layer such as:
Top Layer => *.gtl
Bottom Layer => *.gbl
Keepout Layer => *.gko
TopOverlay Layer => *.gto
BottomOverlay Layer => *.gbo etc.
2. Generating Gerbers in Altium Designer
Add layer stackup to any of the mechanical or other suitable layer.
Add other information like manufacturing notes, dimensions, cutouts etc., before generating gerber files.
In Altium Designer it is very easy to setup Gerber Files creation setup. It is done by two ways:
Generate through File>Fabrication Outputs> Gerber Files
It opens Gerber Setup dialogue box.
In Gerber setup dialogue box Set file producing unit system.
In layers pane add layers to be re-produced in gerber format.
In drill drawing pane click plot all used layer pairs on both of the boxes.
Set apertures box.
Set advanced parameters in advanced pane or otherwise keep default settings.
Click ok , it generates the gerber outputs in the project folder.
On same method NC drill files are created i.e., File>Fabrication Outputs> NC Drill Files and then adopt the same steps as above.
Or in other way it can be generated by following steps:
Output Job File to project > Fabrication Outputs> Gerber Files and then set path for files.
Double click "Gerber Files" it will open Gerber setup. Use the same steps as above and click ok.
Enable output generate option and set target folder location.
Clock Run or double click over generates content. The gerber file outputs will be generated.
Figure 1: Sample PCB Design file
In figure 1 different layers names are shown in their respective layer. The same layers can be viewed in the final view Figure 5 as Gerber output generated.
Figure 2: Gerbers Settings Dialogue Box
Figure 3: Gerber Setup Dialogue Box opens
Figure 4: Gerber Files generated and viewed in CAMTastic Bottom Layer view
Figure 5: CamTastic complete PCB view
3. What is Needed by Manufacturer
In a gerber file following layers and information should be added:
- 1- Enable all signal layers which have been used for routing in PCB design or those which have electrical signals routing should be enabled to re-produce in gerber format.
- 2- Enable all plane layers which are solid copper and distribute power to the circuit on PCB. These are printed as negative image of layer.
- 3- Enable Keepout layer, it is usually electrical boundary of the board. The keepout can also be asked to manufacturer for cutting boundary.
- 4- Enable required mechanical layers in gerber setup. A mechanical layer does not have any electrical information like in signal layer or plane layers. However, they can have some information about mechanical parameter like PCB cutting or, 3D footprints information, assembly and fixing in enclosures etc.
- 5- Enable Top Overlay and Bottom Overlays which have information of components designators and PCB name, number, nomenclature debug information and test signal details etc.
- 6- Dimensional Information: PCB Dimensions information should be added on top overlay or mechanical or keepout layer of PCB design file before generating gerber files.
- 7- Layer stackup: Before generating gerber files add layer stackup information in any enabled mechanical layers so that manufacturer can use information about PCB material such as base material thickness, pre-preg thickness type etc.
- 8- Preferably produce time and date stamped Gerber files so that they would be back traced for any query.
- 9- Recheck and verify the file types using any gerber viewer software tool.
- 10-If found accurate and forward to the manufacturer.
Figure 6: Gerber files enable and disable and extensions
Figure 6 shows the gerber files produced by Altium Designer software, produced time, type of layer etc.
Gerber format is RS-274-X 2D ASCII file format. The gerber file format is a defacto standard of interface between a PCB Design engineer and manufacturer. It includes all conductive, mechanical, text and keepout layers information of a PCB design alongwith necessary notes for manufacturing.
The Altium Designer software produces RS-274-X format Gerber files by different methods. The latest software and updates about files generation are available on Altium ®. In this tutorial a complete yet comprehensive guide has been provide.