![]() When you go to create X2 files for your design, you can create a file for each and every layer in the PCB stackup, including mechanical layers. If the Gerber viewer/editor application you’re using doesn’t understand the Gerber format extension and can’t determine the location in the layer stack, then it will cue up the layers out of order (usually in alphabetical order). The data in these files is all ASCII data, so any number of applications can read that data and use it to generate 2D vector images of each layer. I say “usually” because I’ve received Gerbers as part of projects where the client’s engineer didn’t use the extensions shown above. RS-274-X Gerber files all different extensions, and the extension tells a specific viewer/editor program the function of each file.įor RS-274-X Gerbers, you can usually infer the function of each layer simply by looking at the extension. Under the RS-274-X standard, because there are no attributes attached to the file, the correspondence of each file to a specific layer in the PCB occurs through the extension. The extension has the general format “GXY”, where X and Y refer to a specific function and/or layer assignment for the particular file. From this list of files, we can see that they all have different extensions. The image below shows a set of RS-274-X Gerbers for an example 2-layer PCB. I’ll show the set of Gerbers I’ve generated for a product I’m designing, and we’ll be able to see what the Gerber file extensions mean by looking at the Gerber file extensions under both standards. ![]() To see where the file extensions come into play, it helps to look briefly at an example with a finished PCB layout. To read more about the pros and cons of each format, read this recent (but still relevant) blog post from Ben Jordan. ![]() One set of these files, as well as drill files, a BOM, centroid files, netlists, and a few other fab & assembly drawing files give your manufacturer everything they need to understand your board. Upon the 2014 release, UCAMCO declared the earlier RS-274-D standard “technically obsolete” in favor of RS-274-X and X2 because aperture definitions in RS-274-D are not standardized. X2 format: Upgrades on RS-274-X format to include information on layer location, pads and vias, controlled impedance requirements, and other attributes.RS-274-X format: A 2D vector image of a specific layer in a PCB layer stackup this file format includes aperture definitions, XY coordinate locations for draw and flash commands, unit data, special polygon fill commands, and other information needed for PCB fabrication.Both file formats are ASCII human-readable files that can have any extension, and they can be read in a text editor just like other ASCII files. These supersede the older RS-274-D format, which is no longer supported by its developer UCAMCO. To briefly review, what are the standard Gerber file formats, and what do they encode? The two Gerber file formats are the RS-274-X format (released in 1998) and the newer X2 format (released in 2014). Experienced designers and fabricators have probably decoded the various Gerber file extensions, so this is focused more on newer designers. We’ve discussed what is a Gerber file and the various Gerber formats in other articles on this blog, but we have yet to really dig into the various file extensions for each format. Gerber files are the de facto industry standard format for encoding a PCB layout data into a format that is usable by vector photoplotters. If you’ve ever wanted to decode Gerber file extensions and formats, keep reading to learn more. What might seem like black magic to new designers is secretly intuitive, and it’s not as if one Gerber file extension is objectively “better” than another. The key to building and using these Gerber viewer applications is to understand the various Gerber file extensions and Gerber file formats. Some applications can very nicely reproduce the look and feel of a PCB layout with just a few active layers, such as the Gerber image I’ve shown above from one of our example press-fit connector layouts. ![]() If you’ve ever used an external Gerber file viewer, or you’ve used some PCB design applications with a built-in Gerber viewer, you know there are different formats and file extensions for Gerber files.
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