What to expect when you're expecting (to build a PCBA)

In addition to designing our own boards, we also help others get into production. So we’ve seen quite a few documentation packages from other designers. Some of them are good and some of them honestly suck. Bad documentation means lots of questions from the manufacturer which slows things down and leads to more risk. Good documentation doesn’t mean there will be no questions, but the best kind of question is where you can respond “see PCB Fabrication drawing note 4” or point out that the question has already been answered.

This post will just focus on what files you should have to build a board; both bare board PCB files as well as assembly files. One thing that’s important is to keep the folder organization as “flat” as possible; don’t have a lot of sub-folders. Make it easy for the person to quickly check that everything is there. Also, all files should include the company name, product name, part number, and revision level. If you use Altium it is easy to configure this automatically.

The files that you need are:


  • Gerber files (GBL, GBO, GBP, GBS, etc.) along with the drill files (usually one for holes and one for slots) - these should all be in their own directory since this will be sent to the board fabricator

  • Netlist in IPC-D-356A format - this is used to electrically test the board. And all boards should be 100% electrically tested, even little simple boards.

  • PCB Fabrication Drawing in PDF format specifying the requirements for the board. This will be described in another post.

  • Assembly Drawing in PDF format specifying assembly requirements, like which IPC-6012 class the board is in, post soldering operations, etc. In the past these were used to aid in assembly but now most assembly is done automatically so these are more for reference and notes.

  • Bill of Materials - don’t over-complicate this; it gets sucked into a software program for kitting. The only columns you need are Description, Designator, Quantity, Manufacturer, and Manufacturer’s Part Number. Always use the MFPN, never a Digi-key or other vendor part number. The only exception would be for a mechanical part if you have a McMaster-Carr part number.

  • Pick & Place information: this has the X,Y,Rotation data used to program the pick & place machines

  • While not required, a 3D rendering of the board is helpful to just make sense of it. I provide top, bottom, and isometric views.

  • If the manufacturer will be testing and troubleshooting the board then I recommend providing a schematic as well. I provide a schematic for all boards so that I always have one that is synchronized to the design files.

Derek Smith