How Procurement Should Document an Approved Second Source
An approved second source is only real when you can produce the record that proves it: exact part-number pair, compatibility grade, the evidence behind it, disclosed differences, engineering sign-off and quote-specific commercial terms.
An approved second source is only real when you can produce the record that proves it. The record has to show the exact source part number and the exact alternative, a compatibility grade, the manufacturer evidence behind that grade, the differences that were disclosed, the engineering sign-off, and the quote-specific commercial terms. Without that file, a second source is a conversation, not a backup.
Why the record matters more than the approval
A second source is a pre-qualified alternate supplier for a part you already purchase from a primary source, activated when the primary source fails delivery, raises prices or goes out of business (3E Technology, How to Qualify a Second-Source Supplier). That activation is usually urgent, which is exactly when nobody has time to reconstruct what was approved. Supplier quality programs treat supplier and part approval as a formal process for this reason; a published Supplier Quality Requirements Manual typically includes a supplier approval step and a part approval step, with the buyer holding the evidence (see for example Moxtek's Supplier Quality Requirements Manual).
Procurement should care for three reasons:
- Auditability — your quality system and your customer will ask to see the basis for the approval.
- Handover — the engineer who qualified the part may leave; the record is what remains.
- Accountability — when a line fails, the record shows whether the decision was made on evidence or on a family name.
What a complete second-source record contains
| Field | What to record | Why it matters |
|---|---|---|
| Source part number | Full manufacturer PN including suffix, e.g. STM32F103C8T6 | The record is useless if the suffix is ambiguous |
| Alternative part number | Full supplier PN including suffix, e.g. GD32F103C8T6 | Same ambiguity risk on the approved side |
| Compatibility grade | P2P / PIN / FUNC / REF with its definition | Tells everyone what kind of change is involved |
| Evidence | Datasheet, official migration guide, naming map or cross-reference record with a source URL and date | Distinguishes a documented match from an assertion |
| Disclosed differences | Package, pinout, electrical limits, peripheral and firmware differences | Prevents surprises during validation and production |
| Engineering status | Validation owner, date and outcome | Separates candidate from qualified for production |
| Commercial terms | Quote-specific price, MOQ, stock, lead time, provenance | Prevents evergreen promises that expire |
| Record control | Owner, date, revision | Makes the record auditable |
The rule that keeps the record honest: grade, evidence and differences travel together. If you keep the grade but drop the differences, the record will mislead the next reader.
A worked example from a live cross-reference database
Senneon's cross-reference database stores graded, evidence-backed target-to-supplier matches. Two real records for the same target show what procurement should capture:
| Target | Alternative | Grade | Confidence | Disclosed differences |
|---|---|---|---|---|
| STM32F103C8T6 | GD32F103C8T6 | P2P | high | Max clock 108 MHz vs 72 MHz; flash is zero-wait SRAM-buffered, so timing-sensitive code needs review; ADC behavior differs — validate in circuit |
| STM32F103C8T6 | AT32F413C8T7 | PIN | high | Max clock 200 MHz vs 72 MHz; firmware port required (most registers compatible, not all); operating temperature -40 to +105 °C vs ST -40 to +85 °C |
The GD32F103C8T6 match is backed by GigaDevice's official compatibility summary and a part-number naming map. The AT32F413C8T7 match is backed by Artery's official migration guides archived at a stable evidence URL. Both are engineering-review candidates, not an instruction to skip validation.
Notice that even the P2P match carries disclosed differences. P2P means the manufacturer documents the replacement path, not that validation can be skipped. That distinction is the difference between a useful record and a liability.
How the grade changes what procurement must do next
- P2P — official documented replacement path. Still requires in-circuit validation of your specific application.
- PIN — pin-compatible but needs a firmware port; budget firmware effort and retest.
- FUNC — functionally equivalent; expect a redesign.
- REF — parameters approximate; treat as a starting point, not a drop-in.
For a fuller treatment of what compatible means, see Pin-Compatible vs Drop-In Compatible and How to Qualify a Chinese MCU Alternative.
Where commercial terms belong
Price, MOQ, stock, lead time, sample terms and provenance are quote-specific facts, not evergreen claims. A procurement record should store the quotation or proforma reference, the Incoterm, the validity date and the supplier documents that support provenance, then re-verify them when the alternative is actually activated. Never let a recorded approved alternative carry an unverified price or delivery promise. Ask for a current quotation via the RFQ page.
Tie the record to incoming inspection
The approval record should drive receiving inspection. When a lot of the approved alternative arrives, check the package markings, date code and batch consistency against the record, and keep the inspection result with the record. That closes the loop between the engineering decision and the parts on the line. See Incoming Inspection and Traceability for Semiconductor Sourcing for the receiving-side checklist.
Checklist summary
- Record the exact source PN and exact alternative PN, full suffixes.
- Attach the grade, its definition and the evidence URL.
- List every disclosed difference.
- Record engineering validation owner, date and outcome.
- Store quote-specific commercial terms with the quotation reference and validity.
- Connect the record to incoming inspection.
- Review the record when the dataset, supplier document or commercial policy changes.
If you are maintaining a second-source list and want the evidence and differences already compiled for each candidate, Senneon can review a BOM or a single PN and return a graded, evidence-backed cross-reference for engineering review. Start on the contact page or the RFQ page.
Senneon Engineering Desk · updated 2026-09-02
Frequently asked questions
Can I rely on a supplier's compatibility grade without running my own validation?
No. A grade such as P2P or PIN reflects documented evidence and the level of change involved, but final fitness must be confirmed by your own engineering validation against your application. The grade tells you what to test; it does not replace the test.
Should price and lead time be stored in the second-source approval record?
Only as quote-specific facts with a quotation reference, Incoterm and validity date. Price, MOQ, stock and lead time change, and must be re-verified from a current quotation when the alternative is actually activated.