RS-274X_Extended_Gerber_Format_Specification_201201.pdf

and debugged. Its widespread availability allows PCB professionals to exchange image drill and route securely and efficiently. The RS-274X format is simple, compact and unequivocal. It is easy to interpret. It describes an image with very high precision. It is complete: one single file describes an image. It is portable and easy to debug by its use of printable 7-bit ASCII characters. A well-constructed RS-274X file precisely defines the PCB image data and the functions of the different image elements. Unfortunately, poorly constructed or simply erroneous RS-274X files also circulate, sometimes leading to unjustified criticism of the format itself. Errors may be due to a misunderstanding of the format. With more than 25 years experience in CAM software we at Ucamco know which areas are most often misunderstood. This revision of the RS-274X specification explains these areas more clearly. Other files are not invalid but poorly constructed. Especially troublesome are painted or stroked pads and copper planes. Poorly constructed files take longer to process, require more manual work and increase the risk of errors. This revision of the RS-274X specification recommends constructions to make RS-274X files safer and more efficient, and hence fabrication more reliable, faster and cheaper. A few words must be said about RS-274-D or Standard Gerber. This format was developed to drive NC machine tools and was used for Gerber vector plotters in the 1960s and 1970s. It is not an image description format. It is amazing that it is still used. It is like using teletype paper tape to transfer text documents. We call on industry experts and professional organizations to discourage the use of the obsolete RS-274-D format. Although other data transfer formats have come into the market, they have not displaced RS-274X. The reason is simple. More than 90% of the problems in data transfer are due not to limitations in the RS-274X format but to poor practices and, worse, the use of RS-274-D. To quote a PCB manufacturer: “If we would only receive proper RS-274X files, it would be a perfect world.” The new formats are more complex and less transparent to the user, and new implementations inevitably have bugs. Using the common poor practices in the newer and more complex formats makes matters worse, not better. Fabricators have not adopted the new formats. RS-274X remains the standard. The emergence of RS-274X as a standard for image exchange is the result of effort by many individuals who developed outstanding software for RS-274X files. Without their dedication the widespread acceptance of RS-274X could not have been achieved. Ucamco thanks these dedicated individuals.