A BOM, bill of materials, lists every component on an assembly with quantity, reference designators, description, manufacturer and part number, plus approved alternates. The assembler buys parts and sets up feeders from it, so it must agree with the schematic, the layout and the centroid file. Do-not-populate parts are marked explicitly, and BOM errors such as wrong values or obsolete parts are among the most common causes of a failed first build.
BOM says 10k for R47 but the schematic says 1k, which one do you want us to load?
Also heard as
- bill of materials
- parts list
Related terms
Refdes
Reference designator: the label such as R12 or U3 that names one part on the schematic, board and BOM.
Centroid file
File listing the X-Y position, rotation and side of every surface mount part for the pick-and-place machine.
Pick-and-place
Automated machine that picks surface mount parts from reels and trays and sets them on a pasted board.