How to Prepare a BOM for PCBA Quotation (Template Included)

The six required fields, line by line

These are the columns in our template, and the order matters — it's the order a quoting engineer reads them:

Why the MPN matters more than any other field

A description like RES 10k 1% 0603 matches hundreds of orderable parts from a dozen manufacturers, at prices that differ by a factor of five and stock levels that change daily. The MPN removes that ambiguity: it pins the line to one specific part from one specific manufacturer, with one datasheet.

Three consequences when MPNs are missing:

• Time. An engineer has to cross-reference your description against distributor catalogs for every incomplete line. On a 60-line BOM that turns a 24-hour quote into a week of email ping-pong.
• Price risk. If we guess, we quote the part we found — which may not be the part you priced in your own calculations.
• Silence risk. At factories that don't review by hand, a missing MPN doesn't slow the quote down — it just gets filled with whatever was cheapest that day. That's how silent substitutions happen.

If a line genuinely has no MPN yet (a custom magnetics part, a TBD connector), mark it TBD in the MPN column instead of leaving it blank. Blank reads as "forgot"; TBD reads as "let's discuss" — and it will be flagged to you, not guessed.

Substitution rules: the column that protects you

Shortages are normal. What shouldn't be normal is finding out about a swap after the boards ship. The substitution-rule column settles this before anyone buys anything:

• Exact only — nothing gets purchased except this MPN. If it's out of stock, you get a re-quote with the real lead time. Use this for MCUs, radios, precision analog, connectors, anything firmware- or cert-sensitive.
• Equivalent OK, with conditions — write the conditions on the line: same capacitance, voltage, dielectric, package. A 100nF X7R 0603 has many legitimate equivalents; "same value" alone is not a condition, it's a wish.
• Blank — ambiguous. Our house rule: blank means exact-only. Whatever your assembler's rule is, you want to know it exists before the shortage does.

Five mistakes we see every week

1. Distributor part numbers instead of MPNs. Digi-Key and Mouser SKUs are their internal numbers. Always copy the "Manufacturer Part Number" field, not the order code.
2. Quantity doesn't match designators. R1, R2, R3 with Qty 2. Which is right? Nobody knows without asking, and asking takes a day.
3. DNP rows silently included. Do-not-populate lines with a real quantity get bought and stuffed. Set Qty to 0 and write DNP in Notes.
4. Duplicate designators. Two different parts both claiming C14. Usually a copy-paste error from an old rev of the board.
5. Three revisions in one file. Hidden columns, struck-out rows, a second BOM pasted below the first. Export one clean sheet per revision.

You can check the first four in seconds: drop the file into the BOM check on our homepage — the same first pass our internal tooling runs before a human ever opens your file.

What happens after you send it

Every BOM that comes to us goes through the same path: tooling parses and cross-checks it first (missing MPNs, quantity mismatches, duplicate designators surface immediately), then an engineer reads it — checking lifecycle status, flagging single-source and long-lead lines, and marking anything shortage-prone. You get a quote that says what's in stock, what's not, and what your options are, in 24–48 hours. No line gets swapped without your written approval — that's the same rule the template's substitution column encodes.