The Gerber format is an open 2D binary vector image file format. It is the standard file used by printed circuit board (PCB) industry software to describe the printed circuit board images: copper layers, solder mask, legend, etc.
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.
PCB Outline is required. Drawing board outline in Eagle (layer 20).
Gerber file is used for the manufacturing process.
Below is a picture on how to compress the necessary files.
