A BOM is a list of promises: that each part will be buyable, at that price, at your volume, for the life of the product. This skill reviews a BOM the way a sourcing veteran does — Pareto the cost, flag the single-source and end-of-life traps before they become line-down events, and separate real cost-down candidates from wishful thinking.
What This Skill Produces
- A cost rollup by commodity class with % of total
- Top-10 cost drivers (they usually carry 70–80% of BOM cost)
- Risk flags per line: single-source, lifecycle (EOL/NRND), MOQ mismatch, long lead time
- A prioritised cost-down candidate list with realistic savings and effort
- Tariff and logistics sensitivity notes
Required Inputs
Ask for these if not provided; work with a partial BOM if that's all there is, labelling gaps [missing — request from EE/sourcing]:
- The BOM — part numbers, descriptions, quantities, unit costs (any format; structure it)
- Annual forecast volume — needed for MOQ math and price-break realism
- Target BOM cost — what "good" looks like
- Sourcing detail if available — approved vendors, country of origin, lead times, lifecycle status
- Product stage — EVT-stage BOMs get design-out suggestions; MP-stage BOMs get negotiation/resourcing ones
Review Framework
1. Rollup. Group into commodity classes (PCBA/semiconductors, passives, display, battery, mechanicals/enclosure, cables & connectors, packaging & accessories). Show cost and % per class, and total vs target with the gap.
2. Pareto. Rank the top-10 lines by extended cost (unit × qty). Everything after these is noise until the big ten are handled.
3. Risk flags — apply per line, worst flag wins:
| Flag | Trigger | Why it matters |
|---|---|---|
| 🔴 Single-source | One qualified vendor, no drop-in alternate | One factory fire from line-down |
| 🔴 EOL / Obsolete | Lifecycle status EOL or last-time-buy announced | Forced redesign or LTB cash outlay |
| 🟠 NRND | Not recommended for new design | Fine now, redesign within product life |
| 🟠 MOQ mismatch | MOQ > ~13 weeks of forecast demand | Cash tied up, scrap risk on ECO |
| 🟠 Long lead | Lead time > 16 weeks | Forecast error becomes shortage |
| 🟡 Custom/tooled part | Custom silicon, tooled mechanical | Switching cost locks the vendor in |
4. Cost-down candidates. For each: the lever (negotiate at volume break / second-source and dual-run / value-engineer spec — e.g. tighter-than-needed tolerance, over-spec'd connector / design-out entirely), estimated saving per unit, effort, and earliest cut-in (which build or ECO).
5. Tariff & logistics sensitivity. Note country of origin concentration, HTS-code exposure for high-value lines, and what a duty change or freight spike does to landed cost.
Output Format
BOM review: [product / revision]
- Summary — total BOM cost vs target, gap, one-line verdict
- Cost rollup — table by commodity class (cost, % of total)
- Top-10 cost drivers — table: part, qty, unit cost, extended cost, % of BOM, flags
- Risk register — every 🔴/🟠 line with flag, evidence, and recommended action + owner
- Cost-down candidates — ranked table: lever, est. saving/unit, effort, cut-in point, confidence
- Tariff/logistics sensitivity — exposure summary and scenarios
- Data gaps — lines missing cost, lifecycle, or sourcing data
[missing — request]
Quality Checks
- Rollup total reconciles with the sum of lines — no silent arithmetic drift
- Every top-10 line has a lifecycle and sourcing note, even if
[missing — request] - Each cost-down candidate names the lever, the saving, and the cut-in build/ECO
- MOQ flags are computed against the stated forecast, not gut feel
- Single-source flags distinguish "no alternate exists" from "alternate not yet qualified"
Anti-Patterns
- Do not quote unit prices without a volume — a price without its quantity break is fiction
- Do not chase pennies on passives while a top-10 line is single-sourced and EOL
- Do not claim a cost-down saving without naming the lever and who has to act
- Do not treat distributor stock as supply security for a single-source part
- Do not ignore custom/tooled parts in risk review — they are the hardest to move
- Do not fabricate costs for missing lines — label them and carry the uncertainty into the total