ENGINEERING NOTE · OBSOLESCENCE & LAST-TIME-BUY
Component lifecycle, not capacity, breaks the programme
Semiconductor average life has fallen from about 30 years to about 10, while the equipment those boards sit in is expected to run for 20–30. Capacity problems can be scheduled around; a last-time-buy notice cannot. This note sets out the scan items, the J-STD-048 notice clock, the last-time-buy quantity rule and the substitution rule.
The process engineering team · 11 September 2026
WHY PROGRAMMES BREAK
Four numbers that move a delivery schedule
Capacity is a scheduling problem: add a shift, move a build date, quote a longer lead time. A component that reaches end-of-life is a design problem, and it arrives with a document rather than a delay note.
- ~30 → ~10 years Average semiconductor lifespan
- ~750,000 Components obsoleted, 2022
- 470,000 Reached end-of-life, 2023
- 26–40+ weeks DRAM lead times
Industry-published figures, used here as illustration, not as our own measurements.
WHAT A BOM RISK SCAN ACTUALLY CHECKS
The checks, in order
The scan runs on the bill of materials as received, line by line, before a quotation is treated as firm. Each check exists because it changes what can be promised about the build date.
| Check | What we look at | What it triggers |
|---|---|---|
| Lifecycle statusActive / NRND / EOL | Every MPN against its manufacturer status, plus the published last-order date where one exists | NRND and EOL lines are listed for the customer with a recommended action and the date the decision has to be made by |
| Single sourceno second source | Any MPN with one manufacturer, one package option and no drop-in alternative on the approved vendor list | Flagged for a second-source qualification before the next build, with the parameter comparison done first |
| Long leadagainst the build date | Quoted lead time measured back from the required ship date, including the 12–26 weeks a long-lead semiconductor can add | Either the build date is re-planned, or the part is bought ahead and held against the programme |
| Counterfeit riskAS5553 / AS6081 | Source of supply and lot traceability, checked against the AS5553 and AS6081 anti-counterfeit practices | Franchised or authorised supply only for the affected lines, with incoming inspection on those lots |
| ComplianceRoHS / REACH / 3TG | RoHS and REACH SVHC status of the MPN, and the conflict-minerals position reported through the CMRT | Declarations requested from the manufacturer, or the part is replaced before the design is frozen |
Declarations and test reports are available on request, and the CMRT is refreshed annually.
THE NOTICE CLOCK
Twelve months, then six
When a manufacturer discontinues a part, the useful information is not the announcement but the two dates attached to it. Those dates are what a programme manager can put into a schedule, and they come from J-STD-048.
- J-STD-048 · last order date
- 12 months
- J-STD-048 · final delivery
- 6 months after
- J-STD-046 · change notification
- process and material changes
- Industry-published DRAM lead time
- 26–40+ weeks
Twelve months sounds generous until it is laid against a validation cycle. A medical or automotive build has to re-qualify the assembly, and a first-article approval on a new part can consume a large part of that window before a purchase order is even placed.
Notification is not guaranteed. Parts are discontinued without a buy window, distributors hold stock that is not covered by the manufacturer's notice, and a part that has already passed its last-order date is only available from the open market — which is where the counterfeit risk in the fourth scan line becomes a live problem rather than a checkbox.
PLANNING A LAST-TIME-BUY
Quantity, storage, and what you must not guess
The quantity is arithmetic, not optimism. It is built from what the programme still has to produce, and it is agreed with the customer before the order is placed, because it is the customer's forecast that sets the number.
- Remaining production years × annual usage
- base quantity
- Attrition for scrap and rework
- added
- Samples for verification and first article
- added
- Reserve for a later process change
- agreed, not assumed
STORING WHAT YOU BOUGHT
Parts that sit for years still have to solder
Buying the last reel only moves the problem if the reel is stored badly. Moisture and oxidation decide whether the parts are still usable when the programme reaches them.
- Packaging
- MBB + desiccant + humidity indicator card
- MSL floor life
- per level, logged on opening
- Exposure beyond the limit
- bake before use
- After long storage
- solderability and appearance re-verification
- Records
- lot-level traceability
A grid-equipment manufacturer in the Netherlands moved a 2-layer power board to a BOM risk scan, a second-source qualification and a last-time-buy plan; the product's production life was extended by five years.
SECOND SOURCES NEED WRITTEN APPROVAL
No automatic substitutions — ever
Replacing a part is a design change, and it is treated as one even when two parts look identical on paper. The six steps below are the route a substitution takes, and the third one is not optional.
Scan flag
The scan raises the MPN with its status and the reason: NRND, EOL, single source, long lead or a compliance gap. The reason decides how much time the programme actually has.
Parameter comparison
An engineer compares the parameters that matter to the circuit — ratings, package and land pattern, temperature range, tolerance and derating — against candidates, starting inside the approved vendor list.
Written customer approval
Every substitution requires written customer approval. No automatic substitutions.
Samples and verification
Samples are built and verified against the customer's test specification, with a first-article inspection report on the new part before any volume build is released.
Documentation
The comparison, the FAI report and the customer's written release go into the build file, so the next order and the next audit start from the same record.
AVL and change notice
The part is added to the approved vendor list and the change is notified under the project's change process, with the effective date and the serial range it applies from.
RELATED CAPABILITIES
Where this connects on this site
Component sourcing
MPN-level purchasing with lifecycle screening, long-lead checks and anti-counterfeit sourcing practice on every BOM — incoming inspection on receipt.
Prototype to production
One placement programme from prototype to volume, with first-article inspection before the volume release and the same BOM carried through.
Design and DFM guides
Land patterns, second-source friendly package choices and the DFM report we return inside 24 hours on prototype boards.
SEND US THE BOM
Find out which line stops the programme
Send the BOM with manufacturer part numbers and quantities. We return the lifecycle status of every line, the lead time that actually applies, and the parts that need a decision from you.
Reply within one business day