Bom

BOM Management

BOM data lives in KiCad schematic symbol properties as the single source of truth. This skill orchestrates the full lifecycle: analyze the schematic, search distributors, validate parts, write properties back, export tracking CSVs, and generate order files.

Related Skills

Scripts

Use <skill-path> to reference the BOM skill directory.

# Analyze schematic (JSON output, recursive sub-sheets)
python3 <skill-path>/scripts/bom_manager.py analyze path/to/schematic.kicad_sch --json --recursive

# Export BOM tracking CSV (creates new or merges with existing)
python3 <skill-path>/scripts/bom_manager.py export path/to/schematic.kicad_sch -o bom/bom.csv --recursive

# Generate per-distributor order files (5 boards + 2 spares/line)
python3 <skill-path>/scripts/bom_manager.py order bom/bom.csv --boards 5 --spares 2

# Quick single-distributor order (bypasses Chosen_Distributor column)
python3 <skill-path>/scripts/bom_manager.py order bom/bom.csv --distributor digikey

# Write properties to schematic (dry-run first, then apply)
echo '{"R1": {"MPN": "RC0805FR-0710KL", "Manufacturer": "Yageo"}}' \
  | python3 <skill-path>/scripts/edit_properties.py path/to/schematic.kicad_sch --dry-run

# Sync datasheet URLs from manifest.json back into schematic Datasheet properties
python3 <skill-path>/scripts/sync_datasheet_urls.py path/to/schematic.kicad_sch --recursive --dry-run

# Translate KiCad/Altium BOM and CPL files into JLCPCB upload format
# (`pnp --bom` filter drops orphan designators — see skills/jlcpcb/SKILL.md
# for the 3-step PCBA upload workflow)
python3 <skill-path>/scripts/translate_bom_pnp.py bom input_bom.csv -o jlc_bom.csv
python3 <skill-path>/scripts/translate_bom_pnp.py pnp input_cpl.csv -o jlc_cpl.csv --bom jlc_bom.csv

Workflow

Skip steps that don't apply. Common shortcuts:

• "Add Mouser PNs" — search Mouser by MPN for each part → validate → write to schematic → update CSV
• "Fill in the gaps" — run analyzer with --gaps-only, address each missing field
• "Update datasheet URLs" — run sync_datasheet_urls.py to backfill empty Datasheet fields from the datasheets manifest
• "Prepare for production" — ensure every part has an LCSC number, check stock, set Chosen_Distributor to LCSC

Step 1: Understand the Project

python3 <skill-path>/scripts/bom_manager.py analyze path/to/schematic.kicad_sch --json --recursive

The output tells you the project's field naming convention, which distributors are populated, what's missing, and the preferred distributor. Also look for an existing BOM tracking CSV in the project directory or bom/ folder.

The script covers common patterns, but some projects use internal key systems or parametric fields. See references/part-number-conventions.md for the full catalog. Read the schematic if something seems off.

Step 2: Sync Datasheets

Do this immediately. Datasheets are essential context for validation and part selection. Run the preferred distributor's sync first; if some fail, try others — they share the same datasheets/ directory and skip already-downloaded parts.

python3 <digikey-skill-path>/scripts/sync_datasheets_digikey.py path/to/schematic.kicad_sch --recursive
python3 <lcsc-skill-path>/scripts/sync_datasheets_lcsc.py path/to/schematic.kicad_sch --recursive
python3 <element14-skill-path>/scripts/sync_datasheets_element14.py path/to/schematic.kicad_sch --recursive

DigiKey is best (direct PDF URLs). element14 is reliable (no bot protection). LCSC works for LCSC-only parts. Mouser is a last resort (often blocks downloads).

Tell the user where datasheets are (e.g., hardware/<project>/datasheets/). They'll reference them often.

Cross-revision projects: Use a single shared datasheets directory at the project level rather than per-revision. The same MPN's datasheet doesn't change between revisions.

Re-sync after writing new MPNs (Step 5) — the scripts are idempotent. Then backfill Datasheet URLs into the schematic:

python3 <skill-path>/scripts/sync_datasheet_urls.py path/to/schematic.kicad_sch --recursive

This reads datasheets/manifest.json (legacy name index.json still supported) and writes discovered datasheet URLs into empty schematic Datasheet properties. Opportunistic — only fills blanks. If a schematic already has a different URL, it warns about the mismatch without overwriting (use --overwrite to replace). Run with --dry-run first to preview.

Step 3: Gather Part Information

Watch for comma-separated MPNs. Some symbols track multiple physical parts (e.g., battery holder + clip). Split on commas and search each MPN independently — searching the combined string matches the wrong product.

Search strategy based on what's available:

• Has MPN → search distributors by MPN to get their PNs and stock
• Has distributor PN but no MPN → search that distributor, get MPN, then search others
• Has only Value + Footprint → search by description (e.g., "100nF 0402 X7R 16V")

Use the project's preferred distributor first, then alternates. Prototype: DigiKey primary, Mouser secondary. Production: LCSC.

Step 4: Validate Matches

Don't assume existing PNs are correct — distributor PNs go stale (discontinued, renumbered). Verify existing PNs resolve against the API. If a PN returns 404, flag it for replacement.

For every match, verify:

1. Package matches the schematic footprint (see cross-reference table below)
2. Specs match (capacitance, resistance, voltage, tolerance)
3. Description makes sense (a resistor ref should get a resistor)
4. Lifecycle — not obsolete or EOL
5. Datasheet URL is a direct PDF link (not a product page)

If ambiguous, ask the user. A wrong part is worse than a missing part.

Step 5: Update the Schematic

KiCad coexistence. The script detects KiCad's lock file and warns but proceeds. KiCad doesn't auto-detect external changes — it keeps its in-memory copy. If KiCad is open, tell the user: "Close and reopen the schematic (File → Open Recent) to see the changes. Don't save from KiCad first."

If unsaved KiCad work exists, ask them to save first (Ctrl+S), then run the script, then reopen.

echo '{"R1": {"MPN": "RC0805FR-0710KL", "Manufacturer": "Yageo", "DigiKey": "311-10.0KCRCT-ND"}}' \
  | python3 <skill-path>/scripts/edit_properties.py path/to/schematic.kicad_sch

Backups: By default, no .bak file is created (git tracks changes). Pass --backup if the schematic is not in a git repo or has uncommitted changes the user wants to preserve.

Respect the project's convention. Write to "Digi-Key_PN" if that's what exists, not "DigiKey". Use canonical names only for new projects.

Always write Manufacturer alongside MPN — every API returns it, it's free data.

Step 6: Update the BOM Tracking CSV

python3 <skill-path>/scripts/bom_manager.py export path/to/schematic.kicad_sch -o bom/bom.csv --recursive

CSV columns are dynamic — only distributors the project uses get columns. Base columns: Reference, Qty, Value, Footprint, MPN, Manufacturer. Each active distributor gets a PN column + stock column. Tail columns: Chosen_Distributor, Datasheet, Validated, DNP, Notes.

The Notes column is seeded from schematic BOM Comments properties (or aliases like Notes, Remarks, Ordering Notes, etc.) on first export. On re-export, user edits in the CSV take priority — existing Notes values are preserved and schematic-sourced comments won't overwrite them.

Merge behavior: Re-exporting preserves user-managed columns (stock, Chosen_Distributor, Validated, Notes) while updating schematic-derived columns.

Step 7: Check Stock

For each part with a distributor PN, query current stock via the corresponding distributor skill. Update stock columns in the CSV. Stock data goes stale — note the date and re-check before ordering.

If the chosen distributor is out of stock, flag it and suggest the alternate.

Step 8: Set Chosen Distributor

Factors: stock availability, price at order qty, minimum order/multiples, lead time, shipping consolidation (fewer distributors = fewer shipments).

For prototypes, consolidate to 1-2 distributors (DigiKey + Mouser). For production, LCSC/JLCPCB is cheapest.

Step 9: Re-Sync Datasheets & URLs

Re-run Step 2 (download + URL backfill) to pick up parts added in Steps 3-5. Fast — already-downloaded files are skipped.

Step 10: Validate Datasheets Against Design

Read downloaded datasheets and verify parts are functionally correct for the circuit. This catches wrong-part-number errors that Step 4 might miss.

What to check by type:

• Passives — voltage rating vs rail voltage, temperature coefficient, power dissipation
• Regulators — Vin range, Vout, max current, quiescent current
• MCUs/ICs — supply voltage, I/O levels, peripherals, pinout
• Connectors — pin count, pitch, current/voltage rating
• MOSFETs — Vds, Rds(on), gate threshold, thermal dissipation
• Diodes — Vf, Vr, current rating, recovery time

For large BOMs (50+ parts), focus on power components, critical signal paths, and anything the user flagged. Commodity passives usually don't need deep review.

Step 11: Generate Order Files

Ask how many boards if not already known — this sets the --boards multiplier.

Pre-flight: verify no gaps, CSV is current, Chosen_Distributor is set (or use --distributor flag), stock is fresh.

# Using Chosen_Distributor column, 5 boards + 2 spares
python3 <skill-path>/scripts/bom_manager.py order bom/bom.csv -o bom/orders/ --boards 5 --spares 2

# Or quick single-distributor order
python3 <skill-path>/scripts/bom_manager.py order bom/bom.csv --distributor digikey

--boards multiplies all quantities. --spares adds a flat extra per line after multiplication. --distributor bypasses Chosen_Distributor — generates an order for all parts with that distributor's PN.

Comma-separated PNs (accessories) are auto-split into separate order lines. DNP parts excluded. The script produces one file per distributor in the correct upload format (see references/ordering-and-fabrication.md for format details).

Present the order summary and let the user review/edit before ordering.

Cost estimate: After generating order files, query pricing from distributor APIs at the order quantity and present a total per distributor. See references/ordering-and-fabrication.md for the cost summary template.

BOM Corner Cases & Per-Component Notes

Real projects have BOM quirks that don't fit neatly into standard fields. These are the things that get lost between design and ordering — a connector that's only for prototyping, a cable shared between two boards, a part that needs to be ordered from a specific vendor lot. Actively look for these during BOM analysis; don't wait for the user to mention them.

BOM Comments Field

The BOM Comments symbol property (canonical name) captures per-component freeform notes. It flows into the Notes column in the exported CSV. The script recognizes many aliases: BOM Notes, Ordering Notes, Assembly Notes, Notes, Remarks, Comment, and underscore/space variants.

When to suggest adding BOM Comments:

• Component is prototype-only (DNP in production, or vice versa)
• Component has ordering constraints (minimum order qty, long lead time, specific vendor lot)
• Component is shared with another board (ribbon cables, mating connectors, shared harnesses)
• Component has assembly notes (orientation matters, hand-solder only, apply after reflow)
• Component has substitution rules (acceptable alternates, pin-compatible swaps)
• Component has conditional population (different value for different product variants/SKUs)

Example values:

"Proto only — DNP in production"
"Shares ribbon cable with power board — don't double-order"
"Must be Murata GRM series, no substitution (validated for EMI)"
"Hand-solder after reflow — temperature sensitive"
"Order 10% extra — fragile QFN rework difficult"
"Use 10K for rev A, 4.7K for rev B"
"Mating connector: Molex 39-01-2040 on cable side"