Required columns
A BOM that survives quote review without a back-and-forth has these columns:
| Column | Description |
|---|---|
| Reference | R1, C2, U3 (the designator on the schematic and silkscreen) |
| Quantity | How many of this part on the board |
| Value | Resistance, capacitance, voltage rating where applicable |
| Footprint | 0402, 0603, SOT-23, BGA-256, etc. |
| Manufacturer | Component maker (Murata, Yageo, TI, etc.) |
| MPN | Manufacturer part number |
Optional but helpful: package, tolerance, voltage rating, AVL approval status, alternate MPN.
MPN must be the manufacturer part number
Distributor part numbers (Digi-Key, Mouser, Farnell) are not MPNs. They are catalog references that may map to multiple MPNs depending on availability.
The MPN is the part number on the manufacturer datasheet. Sourcing teams quote against MPN. Substitution decisions key off MPN.
If you have a distributor preference, list it in a separate column. Do not put it in the MPN column.
Alternates
If a part has approved alternates, list each alternate as its own row (or in an alternates column). Do not put alternates in inline comments. Sourcing scripts cannot read inline comments.
A workable format:
| Reference | MPN (primary) | MPN (alt 1) | MPN (alt 2) |
|---|---|---|---|
| R1, R2 | RC0402FR-0710KL | CRCW040210K0FKED | ERJ-2RKF1002X |
BOM-vs-CPL reconciliation
The CPL (also called pick-and-place file or XYZ file) lists each placement: reference designator, X coordinate, Y coordinate, rotation, side (top or bottom), footprint.
The BOM lists what goes at each reference designator.
They must agree on:
- Every reference designator in the CPL exists in the BOM
- Every reference designator in the BOM exists in the CPL
- Quantities match (BOM says quantity 4 for capacitor, CPL has 4 placements)
When they disagree, production stops until you reconcile. Agreeing them before quote saves a week.
Common BOM mistakes that delay production
- Incomplete MPN ("STM32" instead of "STM32F407VGT6")
- Mixed quantities in the same row ("R1-R10, R15", count manually)
- Missing footprint (sourcing has to guess from package)
- Spreadsheet formulas that break in CSV export
- DNP (do-not-place) parts not flagged separately
- Mechanical and packaging items in the same BOM as PCBA components
A quick checklist before sending
- Manufacturer column complete for every row
- MPN column complete for every row
- Footprint column complete for every row
- DNP rows clearly flagged
- Alternates listed in their own column or rows
- File saved as xlsx and csv (some tools prefer one over the other)