This post will cover the essentials of producing manufacturing files for printed circuit board design and fabrication.
It is critical to remember that you are editing a file exclusive to your CAD software when you work on a PCB layout. It is not a universal file format, and it uses information that the PCB manufacturer does not require for proper operation. This is why, when you’re ready to convert the virtual layout to a physical circuit board (except for one file discussed after the article), you must create a different sort of file (except for one file discussed after the article).
What Is a Gerber File and Why Am I Required to Have One?
The Gerber file format is the most widely used in the printed circuit board manufacturing industry. The terms “Gerbers” or “Gerber files” refer to ASCII files containing Gerber-formatted data manufacturers want. A Gerber file has no information about design rules, network connections, or component libraries; it is just two-dimensional artwork indicating were copper, solder mask, or silkscreen will be put during the manufacturing process. A single Gerber file includes a single feature on a single layer of a printed circuit board. For instance, if you have a two-layer board with copper, solder mask, and silkscreen on both sides, you’ll want six separate Gerber files. A second Gerber file will probably be required to identify the board outline. The accompanying picture contains detailed screenshots of my CAD program and the corresponding Gerber files.
Gerber file creation can be a time-consuming and challenging operation. Numerous configuration components are necessary during the process, with specifications differing by the manufacturer.
Suppose you have little or no prior experience with the Gerber generation. In that case, it is advised that you utilize the following strategy: To begin, seek out a pcb manufacturer that will provide extensive instructions on how to create Gerber files using specialized CAD software. Second, use one of these computer-aided design (CAD) applications to develop your board. If you follow the instructions carefully, you will almost certainly avoid the two potential consequences of faulty Gerber files: a manufacturing delay (which is more likely) or a nonfunctional printed circuit board (PCB) (nowadays probably quite rare).
Drill Files are a special kind of file that is used for drilling.
Additionally, a file describing the position and size of each hole that will be drilled into your board will be required, including through-holes (for mounting components) and vias. This is the NC (numeric control) drill file; it is also known as the “Excellon drill file” (which comes from Excellon Automation, a company that makes equipment used in PCB manufacturing). Again, the safest course of action, in this case, is to follow the specific instructions provided by the PCB manufacturer.
Which is superior, ODB++ or Gerbers?
Gerber files are widely accepted, and I recommend that you invest the time necessary to become familiar with Gerber creation and gradually develop a Gerber routine that will enable you to quickly and easily generate PCB manufacturing files for usage in PCB manufacturing facilities. However, ODB++ files may be superior to ODBC files in some instances. Managing several Gerber files may be cumbersome, which is one of the benefits of the ODB++ format: it is a single data structure built (in my experience) without the designer having to do much more than glance at the files.
Although I successfully produced one board using ODB++ files, I ran into some strange complications that prompted me to return to the Gerbers format. The format is irrelevant in and of itself, but in the end, it is irrelevant. If my CAD application cannot correctly generate the files or the fabrication house cannot correctly comprehend them, the format is irrelevant. If you’ve had consistent success using ODB++, we’d love to hear about it in the comments section below. To be candid, it would be ideal if we could all gradually migrate away from Gerbers and toward a more straightforward and robust method of packaging and distributing PCB manufacturing data instead.
Files for Construction vs. Files for Manufacturing
Instead of not producing a manufacturing file, you can find a PCB manufacturer that will accept the project files generated by your CAD application. This is helpful not just for time savings but also because the fab house technicians will (hopefully) know exactly how to develop files suitable with their equipment. I’m assuming that the manufacturer generates Gerbers automatically from the project file.