Accepted File Formats

At PCB Transtek, we can accept a variety of file formats to manufacture your printed circuit board. A list of accepted formats is listed below. Click the link to take you to a more in-depth explanation of each option. We'll be glad to answer any questions regarding the accepted file types or review the files you have if you aren't sure.

TIP:To ensure nothing is lost, please .zip all relevant files into a single .zip or .rar file.
Bare PCB Fabrication
  • Gerber RS-274X (Preferred)
  • ODB++
  • DWG
  • PCB Express (.pcb)
Gerber RS-274X

This is the most current Gerber format and is widely viewed as the accepted industry standard. All modern PCB layout tools will output in this format, older tools may be limited to the obsolete 274D format. 274X (extended) format is preferred since the aperture definitions for interpreting the width, size and shape of the features are embedded within each file as opposed to the original Gerber RS-274D format which relies on generating a separate aperture list for each file.


TIP :  When submitting files in either Gerber format, we also need a CNC Drill file (see below). Depending on your layout software, this may automatically output when exporting your Gerber data, some software packages require this to be exported as a separate step.

TIP:Be careful not to use free layout software distributed by PCB fab (fabrication) shops since they will NOT output Gerber format, you'll be locked into using their service to manufacture your boards.

When outputting RS-274X Gerber format, there will be a separate file generated for each "layer" of your circuit board. An important point to understand is there are two different ways the word "layer" is used in the industry. When discussing the different files that comprise your PCB, each file is considered a layer. Top solder mask layer, top copper layer, top silk screen layer, CNC drill file, etc.


When discussing the specifications of your design on a technical level and for costing purposes, the number of layers refers to how many copper layers your design has. A "4 Layer" board can consist of many different Gerber, drill and fabrication files but in this sense, only contains 4 different layers that contain copper.

TIP:After exporting your Gerber and CNC Drill files, zip them together into a single zip file. We can also accept .rar compressed files. Add any fabrication notes or pictures to the zip that need to be included. Any of these standard formats are acceptable. TXT, PDF, DOC, DOCX, XLS, XLSX, CSV, PPT, PNG, JPG, DWG, etc.

By zipping your files into a single zip, this eliminates the chance that one or more of your files to become separated and lost.


There are dozens of different PCB layout tools on the market which use their own unique naming scheme for Gerber files. Gerber file extensions for some of the most popular PCB layout tools are compared below.


Common PCB Layout Software Gerber File Extension Comparison

Altium / Protel Eagle KiCad Orcad PADS
Native Project Save File .PCBPRJ .BRD .PCB
Top Copper .GTL .CMP / .TOP F.CU .TOP L1.PHO
Inner Signal .G1, .G2, etc .LY2, .LY3, etc - .IN1, .IN2, etc L2.PHO, L3.PHO, etc
Inner Plane .GP1, .GP2, etc - - - -
Bottom Copper .GBL .SOL / .BOT B.CU .BOT L4.PHO (L2 if only 2 layers)
Drill Drawing .GD1 .DIM / .MIL / .GML - - D1.DWG
Drill Guide .GG1 .DIM / .MIL / .GML - - -
Keep out .GKO - - - -
Board Outline .GM1/ .GM3 .DIM / .MIL / .GML EDGE.CUTS .FAB -
Excellon Tool List - - - - -
Excellon Drill Description - .DRD - - -
Note .GKO layer is sometimes used incorrectly as a board outline. Extensions will change depending on software version. These are internal file names to KiCad. Protel naming can be selected when exporting Gerber.
Blanks indicate there isn’t a specific file for this layer or none was found at the time the chart was compiled. If you have additions or corrections, please contact us.
CNC Drill File

The CNC (Excellon) drill file is the file used to program the CNC drill equipment responsible for drilling the holes in your design. This is a different file format than Gerber. This file is output as simple text and can be read in any text editor such as Notepad, WordPad or Word.

TIP:The most universally accepted format to export your drill file in is: Excellon Format, ASCII Odd/ None, 2.4 Trailing Zero Suppression, English Units, No Step and Repeats.

Stands for Open Data Base, the '++', an homage to the C++ programming language, was added in 1997 when component descriptions were added to the output content. With this data standard, there is no need to create a separate CNC Drill file or netlist. The goal of ODB++ is to embed information that is normally found within a fabrication drawing, directly into the file structure. This format is gaining popularity and we have no trouble manufacturing from this format.


The output created with ODB++ is very complex, it creates a myriad of folders and subfolders. Please compress your ODB++ output using a compression tool. For ODB++ files, we recommend 7-Zip, and use either the .tgz or .tar file extension. Standard .zip or .rar compression is also acceptable.


DWG is a proprietary file format used by CAD systems such as AutoCAD. These tools are not ideal choices for creating PCB layouts and were not designed for this purpose, but some simple designs can be created using these tools. We have successfully converted some DWG files into Gerber RS-274X/CNC Excellon format and manufactured from these files. We need to review them on a case by case basis to see if your file can be converted.

PCB Express (.pcb)

This is a proprietary format created from PCB Express's 'Express PCB' software line. As of this writing, we have a tool that can convert this into standard RS-274X/CNC Drill format. We strongly recommend against using "free" fab shop software for layout since the software will only export a proprietary file format only they can open, forcing you to use their service making the software anything but "free."

Solder Paste Layers

In order to place solder paste in exactly the correct location of your PCB, a stencil is needed. A stencil is a flat stainless steel sheet that has openings laser cut into it to correspond to the surface mount pads on your PCB. The stencil can be anywhere from 2-15mils thick depending on how much solder paste needs to be deposited. The average stencil is between 4-5 mils thick. The thicker the stencil, the more paste will be applied to the board. Stencils are cut using the paste layers from your Gerber data as reference. Paste layers look the same as solder mask layers except they omit any apertures that are not needed for automated pick and placement such as thru hole components.