At PCBasic, we rely on Gerber files as the universal vector format for transferring PCB design data from CAD tools to our advanced manufacturing systems. These files contain essential information for every PCB layer and design aspect, including copper traces, solder mask, silkscreen, and drilling. Each file type corresponds to a different element of the board, allowing our automated lines to accurately reproduce your design. In manufacturing, Gerber files are often referred to as photoplot files. Understanding the formats and extensions generated by various design software ensures seamless data transfer and error-free PCB production.
Gerber files follow the EIA-defined standard and are classified into two main versions: RS-274-D and RS-274-X. The RS-274-X format is an enhanced, self-contained version that includes aperture and layer information directly within the file. At PCBasic, we strongly recommend that customers provide Gerber files in RS-274-X format, as it simplifies processing, reduces setup time, and improves overall manufacturing accuracy. This ensures smooth coordination between your design team and our production engineers—leading to faster turnaround and higher precision in every PCB we manufacture.
Below is a chart prepared by PCBasic, summarizing the key contents of different Gerber file types used in PCB manufacturing:
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File Type
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Description
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Common Extensions
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Copper Layer Files
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Contains the circuit traces on the PCB.
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.GTL (Top Copper), .GBL (Bottom Copper)
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Silkscreen Files
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Includes component identification, markings, and text information.
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.GTO (Top Silkscreen), .GBO (Bottom Silkscreen)
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Solder Mask Files
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Defines pad and exposed copper areas to prevent solder overflow.
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.GTS (Top Solder Mask), .GBS (Bottom Solder Mask)
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Solder Paste Files
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Defines where solder paste is needed during reflow soldering.
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.GTP (Top Paste), .GBP (Bottom Paste)
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Mechanical Layer Files
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Contains PCB outlines, cut lines, and other mechanical structures.
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.GKO or .GM1
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Drill Files
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Records the locations and sizes of holes on the PCB, including through-holes and blind vias.
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Next, PCBasic will walk you through the Gerber file types and extensions commonly generated by several popular PCB design software tools.
KiCad
• F_Cu.gbr: Top copper layer
• B_Cu.gbr: Bottom copper layer
• F_Silkscreen.gbr: Top silkscreen layer
• B_Silkscreen.gbr: Bottom silkscreen layer
• F_Mask.gbr: Top solder mask layer
• B_Mask.gbr: Bottom solder mask layer
• F_Paste.gbr: Top paste layer
• B_Paste.gbr: Bottom paste layer
• Edge_Cuts.gbr: Board outline layer
• NPTH.drl / PTH.drl: Non-plated / plated drill files
Eagle
• gtl / gbl: Top / bottom copper layers
• gto / gbo: Top / bottom silkscreen layers
• gts / gbs: Top / bottom solder mask layers
• gtp / gbp: Top / bottom paste layers
• gko / gm1: Board outline layer
• drl / txt: Drill file
Cadence Allegro
• TOP.art / BOTTOM.art: Top / bottom copper layers
• SILK_TOP.art / SILK_BOTTOM.art: Top / bottom silkscreen layers
• SOLDER_TOP.art / SOLDER_BOTTOM.art: Top / bottom solder mask layers
• PASTE_TOP.art / PASTE_BOTTOM.art: Top / bottom paste layers
• OUTLINE.art: Board outline layer
• DRILL.art: Drill file
• .rou: Slot hole drill file (for oval or rectangular holes)
• art_param.txt: Aperture parameter definitions
• nc_param.txt: NC drill parameter file
Altium Designer
• .GTL / .GBL: Top / bottom copper layers
• .GTO / .GBO: Top / bottom silkscreen layers
• .GTS / .GBS: Top / bottom solder mask layers
• .GTP / .GBP: Top / bottom paste layers
• .GM1 / .GKO: Board outline layer
• .TXT: Drill file
