Sourcing
BOM Submission Guide
2026-06-04 · 4 min readReviewed by Zhao Lin, Sourcing
An incomplete BOM is the single most common reason a PCBA quote takes three days instead of one. Every ambiguous line becomes an email, and every email costs you a business day across time zones. This guide covers what we need and why.
Download the BOM template — the five required columns plus alternate, DNP, and sourcing, with worked example rows.
The five columns we need
| Column | Why it matters |
|---|---|
| Designator | Maps the part to a footprint on the board. R1, R2, R5 in one cell is fine; one designator per line is better. |
| Manufacturer Part Number | The only unambiguous identifier. Distributor codes alone are not enough — they change and they are region-specific. |
| Manufacturer | Two makers can share a part number suffix. Pair MPN with manufacturer and the ambiguity disappears. |
| Quantity per board | Per board, not per order. We multiply; you do not need to. |
| Package / Footprint | Lets us cross-check the MPN against your placement file before parts are bought, not after. |
Description, reference links, and internal part numbers are welcome but optional.
Alternates are worth more than you think
A component with no approved alternate is a component that can stop your build. When a part goes to a twelve-week lead time, an approved alternate is the difference between shipping on schedule and waiting.
Add an Alternate MPN column, or mark the line alternates OK when any functionally equivalent part will do. Be explicit about what "equivalent" means for that line — tolerance, voltage rating, and temperature coefficient are usually where it matters.
For parts where no substitution is acceptable, say so. Do not substitute on a line is a useful instruction; silence is not.
DNP and no-fit lines
Mark them clearly in a status column: DNP, Do Not Populate, or No Fit. Leave the line in the BOM rather than deleting it. A missing designator makes us ask whether it was intentional; a line marked DNP answers the question before it gets asked.
Consigned and partial-turnkey lines
If you are supplying some parts yourself, mark those lines Consigned in a dedicated column. Send the same BOM either way — one file with a sourcing column is easier to reconcile than two files that drift apart.
Include the quantity you will ship us, and ship attrition stock on top of the build quantity. Fine-pitch parts and 0201s get lost in the machine; five percent extra is a reasonable starting point.
What slows a quote down
- Distributor part numbers with no MPN. Stock codes expire and differ by region. We cannot buy against them reliably.
- Merged cells and multi-row headers. Spreadsheets built for humans do not parse. Keep one header row and one part per row.
- Quantities given per order instead of per board. This is the error most likely to survive review and reach production.
- No package column. Without it, a mismatch between BOM and placement file surfaces after parts are purchased.
- Images of a BOM. A screenshot or PDF export cannot be searched or cross-checked. Send
.xls,.xlsx, or.csv.
Before you send
- One header row, one part per line
- MPN and manufacturer on every line that is not DNP
- Quantity is per board
- DNP and consigned lines marked in a status column
- Alternates noted, or
do not substitutestated - Saved as
.xls,.xlsx, or.csv
A BOM that clears this list is usually quoted within one business day. One that does not typically costs two extra rounds of questions.
Ready to send it? Start a PCBA quote and drop the file into the BOM slot.
Reviewed by Zhao Lin, SourcingUpdated
Figures reflect current partner-line capability. Confirmed per project at quotation.
Put the guide into practice
Open the instant quote tool with your layers, size, and quantity.