Guides / Files
BOM and CPL files: what an assembler needs
The two files that turn your board into an assembled one — what goes in each, and how they differ across CAD tools.
To assemble your board, a shop (or your own machine) needs two files besides the Gerbers: a BOM and a CPL. Get these right and setup is quick; get them wrong and you get emails.
The BOM (bill of materials)
The BOM lists every part: reference designators, value, package, and a manufacturer or distributor part number. Group identical parts on one line with all their designators — the part number is what actually gets ordered, so a value alone isn't enough.
The CPL (centroid / pick-and-place)
The CPL — also called the centroid or placement file — gives each part's X/Y position, rotation and side. This is what positions the nozzle, and rotation is the field that trips everyone up; see why placements need rotation correction.
Every CAD tool is different
KiCad, Altium, EAGLE, Fusion, DipTrace and EasyEDA all export these with different column names and units. The SMTPlace converter reads all of them, normalizes the rotations, and writes a clean placement file for your machine.
It won't build the BOM for you, but it turns any of those CPL exports into a machine-ready job.
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