Once, in an electrical circuits class, I had a laboratory professor who forced his students to write their reports in ink. At the time, I thought this was a ridiculous idea as it forced me to rewrite many reports due to spelling or grammatical errors. I have since come to realize that he was actually teaching us two things. First, that no job is finished until the paperwork is complete, and more importantly, the paperwork must be accurate. For a PCB designer, these lessons are invaluable.
After spending a tremendous amount of time getting your design just right, it can be tempting to simply crank out the PCB file just to be finished with the process once and for all. However, your contract manufacturer’s (CM’s) ability to build your board rests entirely on the completeness and accuracy of the PCB file you provide. Therefore, your design is not complete until you complete the manufacturing stage of the PCB design tasks. Let’s discuss what your PCB file should include and compare some of the more common formats to see which ones meet or exceed the requirements to ensure a smooth transition from your design to your CM’s manufacturing process.
PCB File Essentials
For the PCB development process (which includes design, manufacturing and prototyping) to proceed efficiently, you must furnish your CM with all essential data and information about your design. Essentials to include in your PCB file fall into three categories: PCB materials, PCB layout and PCB stackup. The information that should be provided for each category is presented below:
- PCB layout
- X-Y data – locations for component pads, drill holes, traces
- Clearances for solder mask, board edge, drill holes
- Silkscreen information for component footprints, reference indicators, polarity and pin 1 markings
- Graphical image of layout
- PCB stackup
- Layer materials
- Layer thickness
- Copper thickness
- Via options and size information
- Layer materials
The above design for manufacturing (DFM) essentials should be based on your CM’s capabilities. If your CM performs the PCB assembly, an accurate and complete BOM is required and your PCB file should incorporate design for assembly (DFA) specifications derived from information and consultations with the CM. Altogether, the PCB layout, PCB stackup and BOM should provide all the data, information and imagery needed for your CM to manufacture your boards.
Not providing your CM with complete and accurate information for your design may lead to extended turnaround times due to the required back-and-forth to correct PCB layout or stackup specifications that fall outside the tolerances of your CM’s equipment.
PCB File Formats
The first accepted standard for the format of a PCB file was the Gerber file (RS-274D), which was an ASCII file with information for board fabrication. This was replaced with Gerber file (RS-274X), a collection of computer-aided manufacturing (CAM) 2-D images that include the PCB layout, PCB stackup, drill holes and board layout. These PCB files are usually accompanied by a text file that furnishes additional information about the design. Although these design files continue to be used today, they present numerous drawbacks, including the propensity for error among the various required files. The latest version, Gerber X2, has not gained widespread acceptance.
Due to the complexity of today’s designs and equipment nuances, more PCB manufacturers want designs in a preferred data transfer format that is similarly comprehensive to CAD files. The drawback here is that virtually all CMs use a different native CAD file format. To address this issue, groups like the IPC-2581 Consortium are pushing for a global standard to facilitate an open and efficient transfer of PCB design data between the designer and the CM. Some of the more common, currently used PCB file types containing the essentials required by your CM are listed below:
📄 Gerber (RS-274X)
📄 .PcbDoc (native for Altium)
📄 .kicad_pcb (native for Kicad)
📄 .brd (native for Eagle)
📄 .dip (native for Dip Trace)
📄 .pcb (native for Cadence)
Regardless of the PCB file format you use, the quality and efficiency of your PCB development process will depend on your incorporation of your CM’s specifications as well as the completeness and accuracy of the file contents.
Tempo Automation, the industry leader in fast, precise, high-quality prototype PCB manufacturing, can utilize any of the native PCB files listed above for your design.
|Tempo‘s Custom PCB Manufacturing Service
And to help you get started on the best path, we furnish information for your DFM and enable you to easily view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on PCB files or want to ensure that your PCB file format includes essential information for your board’s fabrication and PCB assembly, contact us.