Guides
Guides to BOMs for PCB assembly, quoting and purchasing
Twelve short guides on the BOM questions that stall a quote: which columns to include, how designators and DNP lines are read, why a part needs both an MPN and an internal number, and how to cost and order a build. Each gives the short answer first, then steps, one table and the mistakes to avoid.
Where to start
Start from what you are doing
- Preparing a BOM for a quote: BOM for assembly quotes, then BOM formats for PCB assembly.
- Cleaning a BOM that arrived as a PDF: OCR pitfalls in part numbers, then BOM consolidation and duplicate lines.
- Working out what a build will cost: BOM cost rollup in Excel, then Quantity per board vs order quantity.
Read and structure
Reading and structuring a BOM
What the columns mean, how part identity is recorded, and how an export maps to a clean file.
BOM formats for PCB assembly
The columns assemblers expect, and consolidated versus per-designator rows.
Reference designators explained
Prefixes, ranges, and what a designator count proves.
MPN vs internal part number
Why a BOM needs both, and how to keep a mapping table.
KiCad and Altium BOM export columns
Typical export fields, and how they map to a clean BOM.
Clean the lines
Cleaning lines before you send them
Unfitted parts, duplicates, alternates and misread characters: the lines that cause questions.
DNP in a BOM
How to mark do-not-populate lines, and how they get read.
BOM consolidation and duplicate lines
Merging same-MPN lines without losing designators.
Alternate and substitute parts
Recording alternates without breaking the count.
OCR pitfalls in part numbers
Look-alike characters, lost suffixes and a verification routine.
Quote, cost, control
Quoting, costing and change control
What a quoting team needs, how to roll up cost and order quantity, and how to keep revisions straight.
BOM for assembly quotes
What a quoting team needs to price a build.
BOM revision control
Rev letters, change logs and matching Gerbers.
BOM cost rollup in Excel
Unit cost, price breaks and NRE, with a worked table.
Quantity per board vs order quantity
Panels, attrition and MOQ between the BOM and the order.
Tools
Tools that go with the guides
BOM to CSV
Convert a PDF BOM to a fixed ten-column CSV, with the checks.
Designator count check
Compare each line's quantity with its designator count.
BOM template
The columns BOMParser writes, with an example row for each.
PDF BOM to Excel
The same result as a workbook with a Checks sheet.
Free: 1 file per day, up to 10 pages, no account. Files over 10 pages are converted up to page 10 on the free allowance; a page code converts the whole file, up to 150 pages. Pricing lists the plans.