What does a component substitution approval need?
Name both the original and candidate manufacturer part numbers, including the orderable suffixes that affect package, rating or supply format. A similar description, matching footprint or distributor cross-reference can help discover a candidate; it does not prove that the candidate is approved for your complete product.
| Check | Evidence to compare | Approval issue |
|---|---|---|
| Identity and lifecycle | Exact manufacturer MPN, datasheet revision and current product status | Is this an orderable candidate, and is its status suitable for the product? |
| Electrical behavior | Relevant ratings, tolerances, timing, power and operating limits | Which differences affect the circuit or its intended use? |
| Mechanical and assembly fit | Package, pin mapping, land pattern and processing constraints | Will the candidate fit and use the approved assembly route? |
| System impact | Firmware, calibration, interfaces and product requirements | Does a change require software, test or design validation? |
| Sourcing | Approved source, packaging and required traceability | Is the quoted source acceptable, not merely available? |
| Authorization | Named customer approval, effective revision and quantity | What may be purchased or fitted, and where is use prohibited? |
| Verification | Risk-based validation and acceptance records | What must pass before the changed build is released? |
This is a buyer approval checklist, not a guarantee of equivalence, component authenticity or product compliance. The responsible design authority must decide which technical checks and validations apply.
Handle obsolete components as a product decision
Check the manufacturer's current status and any applicable change or discontinuance notice, not just a cached distributor listing. Active, not recommended for new designs, last-time-buy and obsolete are different lifecycle signals. For example, TI defines these categories on its official product lifecycle page; definitions and notices for another manufacturer must be checked with that manufacturer.
For obsolete components in PCB assembly, possible responses include approved existing stock, a validated alternate or a revised design. A last-time buy may preserve an existing product temporarily but also commits cash and creates storage, demand and eventual redesign exposure. It is not automatically the best choice for a new product or a promise of long-term availability.
| Situation | Decision to make | Record before purchase |
|---|---|---|
| Exact part is constrained | Wait, consign, change batch or review an alternate | Confirmed availability, source and revised schedule assumptions |
| Part is NRND or nearing discontinuance | Evaluate continuing use and a transition plan | Manufacturer status/notice, product horizon and review owner |
| Part is obsolete | Review acceptable stock, validated replacement or redesign | Source risk, validation needs and remaining production scope |
| Alternative needs a board or firmware change | Issue a revised product definition | New BOM/layout/firmware/test revisions and old-stock disposition |
Keep approved alternate parts tied to a released BOM
Record each allowed candidate against the affected reference designators, product variant and effective revision. Separate candidates under review from parts already approved. If one alternate is accepted for a prototype, record whether that approval also applies to recurring production; do not silently extend a temporary deviation to all future orders.
- Original manufacturer/MPN and proposed manufacturer/MPN.
- Affected BOM lines, reference designators and quantity.
- Reason for change and documented electrical, package and system differences.
- Required sourcing, traceability and handling restrictions.
- Validation scope, result and any remaining accepted exception.
- Approver, approval date, effective revision and allowed use.
- Disposition of purchased old material and unused candidate stock.
Download the blank alternate-approval record (.txt). This is a planning template: filling it in is not approval by VeriPCB or by the component manufacturer.
Separate authorized sourcing from technical approval
Source acceptability and circuit suitability are two checks, not one. TI recommends buying its products directly or through its authorized distributors to reduce counterfeit risk. Apply the relevant manufacturer's current sourcing guidance; do not infer that a label, picture or generic certificate verifies a particular lot.
Likewise, a genuine part can still be wrong for the circuit or the released BOM. Agree source restrictions, the evidence needed for exceptions and who may authorize them. This guide does not assert that VeriPCB is an authorized distributor or that every component purchase has the same source conditions.
A controlled approval flow
- 01
Propose
Identify the shortage, exact candidate and affected build.
- 02
Compare
Record technical, source, lifecycle and inventory differences.
- 03
Validate
Complete the checks selected by the responsible design authority.
- 04
Release
Record approval, effective revision, purchasing scope and stock disposition.
Use the lead-time gate worksheet to update the plan after a material decision. Use the test requirements guide to define verification rather than asking a supplier for an undefined “equivalent” part.
Alternate and obsolete-part questions
Can a turnkey assembler choose an alternate part without approval?
Only if the released agreement already grants a clearly defined authorization for that use. Otherwise the candidate remains a proposal until the authorized customer approver accepts the part, affected build and any required validation.
Does a matching footprint prove a replacement component is compatible?
No. Compare the exact part's electrical, mechanical, processing and system requirements, including firmware or test impact where relevant. The design authority determines the necessary validation.
What should I do when a PCBA BOM component is obsolete?
Verify the manufacturer's current status and notice, then review acceptable remaining stock, a validated alternate or a design change. Record source, lifecycle, inventory and validation risks before committing to a purchase.
Technical references
Use the applicable standard revision and the component manufacturer's documentation when defining your requirements.
Review a sourcing exception before commitment
Describe the affected BOM references, original MPN, candidate MPN, quantity and unresolved constraints. Share a non-confidential brief; VeriPCB does not approve an electrical redesign on the basis of this checklist.
Request a sourcing-scope review