Electronic Parts Data Management for Small EMS and OEM Teams

Electronic parts data management means keeping one clean, trusted record for every part you buy or build with. Engineering, purchasing and production all use that same record, in the same way. For a small EMS or OEM team, the record can live in a spreadsheet, as long as someone checks it before every quote and every build.

The phrase covers three overlapping jobs: component master data, lifecycle and compliance data, and parts inventory. Master data is one record per part, with your internal part number, the manufacturer part number (MPN), description, package and approved sources. Lifecycle data says whether a part is active, not recommended for new designs (NRND) or obsolete, and inventory says what sits on which shelf.

The master record ties the other two together, which makes it the core of electronic component data management. The rest of this page is a reference for that record: the fields it needs, the errors that break it, a scrub checklist, and where to keep it.

The part record, field by field

You do not need a hundred attributes per part. You need the fields that stop wrong parts, late parts and failed builds. Here is a minimum set of part master data that fits in one spreadsheet row.

A note on MSL. The moisture sensitivity level sets a part’s floor life: how long it may sit in factory air after its dry bag is opened, before reflow. In a Texas Instruments table based on J-STD-033, MSL 3 allows 168 hours at up to 30 °C and 60% RH, while MSL 6 must be baked before use.²

With the MSL in the record, the kit sheet can tell the operator to log the bag-open time. The handling rules behind that step come from IPC/JEDEC J-STD-033.³

Error catalogue

NEMI (now iNEMI) described the BOM quality problem in a 2002 white paper. One leading EMS provider reported on its first two to three months with a new customer. In that period, an average of 80% of the BOMs it received had errors to resolve with the OEM.⁴

The team gathered this as anecdotal information from several OEMs and EMS providers, so treat the number as a field report, not a survey. The paper names incomplete data as the most common defect. It also reports that missing approved manufacturer lists cause most problems.⁴

Duplicates also hide in your own part master, not only in customer BOMs.

Example (illustrative, assumed figures): at a 60-person EMS, a buyer finds one 10 µF capacitor under three internal part numbers, and engineering approved only one. Stock is split three ways, so the buyer reorders a part already on the shelf. Merging the three into the approved record, and allowing each MPN on only one record, fixes both problems.

Scrub checklist before an RFQ

A BOM scrub is a line-by-line check of a bill of materials before you quote or build it. Run it at the purchasing desk before the RFQ goes out, then again before kitting. Copy this BOM scrub checklist into your quoting procedure.

1. Get the BOM as Excel or CSV, not PDF, with its revision and date.
2. Confirm the BOM revision matches the drawings, Gerbers and placement file.
3. Check that every line has an internal part number, MPN, manufacturer, quantity, designators and description.
4. Merge duplicate lines and add up their quantities.
5. Expand designator ranges and compare the count with the quantity per board.
6. Set one unit of measure per line, and convert reels and cut tape to pieces.
7. Look up every MPN and flag anything that is not an exact match.
8. Compare each looked-up description with the BOM: value, tolerance, package.
9. Flag obsolete, NRND, end-of-life and last-time-buy parts.
10. Count approved sources per line and flag single-source parts.
11. Check RoHS and REACH status against the customer’s requirement.
12. Record the MSL of every surface-mount part and flag anything above MSL 1 for dry storage.
13. Check stock and lead time at the build quantity, not at one piece.
14. Save price breaks with the date and the quantity they apply to.
15. Mark do-not-populate (DNP) lines and customer-supplied parts.
16. Send the customer one question list, then write the answers and their dates into the BOM.

For the lookup steps, chip.parts is a live tool that checks part descriptions, price and stock, datasheets and MSL ratings across a part list before an RFQ.

The checklist flags problems; it does not fix them. An engineer approves any alternate, and the customer approves every change to its own design, in writing.

Spreadsheet, parts database or PLM

Spreadsheets are common. In 2016, Arena Solutions, a vendor of product lifecycle management (PLM) software, surveyed 405 product companies. Of those, 48.4% managed BOMs in a spreadsheet (34.6%) or with nothing at all (13.8%).⁵ Two-thirds of respondents represented organizations with fewer than 500 employees.⁵ The question is when a spreadsheet stops being enough.

For the middle row, one open-source option is Part-DB, a web-based inventory system for electronic components. It can pull part data, datasheets and prices from providers such as Octopart, Digikey, Farnell, Mouser and TME, and its documentation says small companies and universities use it.⁶ PLM pays off when your team already works through formal change orders. It does not clean up bad part data by itself.

Keeping it fresh

Part data goes stale on its own. Stock moves every day, prices change, and parts reach end of life, so a record that was right at the last quote can be wrong at the next build.

• Re-check before each quote and each build, and date the check. Lifecycle, stock and price can change between checks, so a fixed monthly check can miss next week’s build. Put a “checked on” date next to each of those fields; a value with no date is a guess.
• Watch for discontinuance notices. JEDEC’s J-STD-048 standard, which supersedes JESD48, covers how suppliers notify customers when a product is discontinued.⁷ Sign up for alerts on the parts you build most.
• Re-check compliance when the rules change. Companies may have legal obligations from the date ECHA adds a substance to the REACH Candidate List.⁸ Which duties apply depends on your role, for example producer, importer or supplier of articles in the EU or EEA, and on the substance and thresholds. For articles, the duties ECHA lists apply when the substance is above 0.1% weight by weight (w/w). Notification to ECHA is required only above one tonne a year per producer or importer.⁸ RoHS exemptions change too, through delegated directives the Commission adopts.⁹
• Compare revisions between quote and build. List what was added, removed or changed between the BOM you quoted and the one you build. How to Compare Two BOM Revisions in Excel shows the method, and a web tool that compares two Excel tables does it without formulas.