Electronic components do not expire. What ages in storage is not the silicon, it is the solderability of the leads and, on a small number of families, the internal chemistry. A resistor with a 2014 date code that has sat in a sealed reel is almost certainly good. An aluminium electrolytic capacitor with the same date code that has sat in a warm warehouse needs re-forming before it goes anywhere near a reflow oven. Age alone is not a reject reason, and treating it as one throws away perfectly usable stock.
This matters commercially in two directions. If you are buying through the independent channel, older date codes are common and you need a defensible accept-or-test policy rather than a blanket cutoff. If you are holding surplus, the date code is one of the biggest levers on what a buyer will pay for it.
What actually degrades, and what does not
The die inside a packaged semiconductor is protected and does not meaningfully age on a shelf. Four things do age:
- Lead and termination finishes oxidise. This is the dominant failure mode. Oxidised leads do not wet properly during reflow, producing cold joints or opens. It is a process problem at assembly, not a device problem.
- Moisture is absorbed by plastic packages once the dry-pack barrier bag is opened, which causes delamination and popcorning at reflow.
- Electrolytic capacitor oxide layers degrade when the part sits unpowered for years.
- Tin whiskers grow on pure tin finishes, and whisker length increases with both storage time and plating thickness.
Realistic storage life by component family
| Component family | Practical storage life | What degrades | Action before use |
|---|---|---|---|
| Resistors, ceramic capacitors, inductors, sealed and dry | 10 years or more | Termination oxidation only | Visual check, solderability sample if beyond policy |
| Standard ICs and discretes in unopened dry pack | 5 to 10 years | Lead oxidation, bag seal integrity | Check humidity indicator card, solderability sample |
| Moisture sensitive devices, bag already opened | Floor life measured in hours, not years | Absorbed moisture | Bake and re-seal per J-STD-033 |
| Aluminium electrolytic capacitors | About 2 years before treatment | Oxide layer, electrolyte | Voltage re-form through a series resistor |
| Pure tin plated leads | Risk rises continuously | Tin whisker growth | Assess per JESD201, prefer matte tin or SnPb for high-reliability work |
| Modules containing cells or batteries | Per datasheet self-discharge | Cell capacity | Measure, plan replacement |
What the standards actually say
There is no standard that declares a component dead at a given age. There are four documents that matter, and they say different things:
- IEC 61760-2 (current edition 3.0, 2021) is the strictest number in common use. It recommends that total storage time across manufacturer and customer should not exceed two years, and should be limited to one year after the customer receives the parts. Read it as a processing recommendation for trouble-free assembly, not as a cliff edge at 24 months.
- J-STD-002, the joint EIA, IPC and JEDEC standard, defines the solderability test methods for leads, terminations, lugs, terminals and wires. It tells you how to test. It does not tell you when.
- J-STD-020 and J-STD-033 govern moisture sensitivity classification and floor life. Once a dry-pack bag is open, these override every other clock. Our guide to moisture sensitivity levels, floor life and baking covers the handling rules in detail.
- GEIA-STD-0003 covers long term storage of electronic devices and is aimed at programmes that must hold stock for decades rather than years.
Practice at the conservative end of the market has actually relaxed. The US military eliminated blanket date-code restrictions on parts, and NASA now reviews parts at around five years to decide whether testing is warranted rather than scrapping them outright. If the organisations with the lowest risk tolerance in the industry stopped using age as an automatic reject, a commercial OEM has little reason to.
How to read a date code
The common format is YYWW: a two-digit year followed by the two-digit week of manufacture. A part marked 8332 was made in week 32 of 1983. Some manufacturers use YWW, some prefix a plant or fab code, and the accompanying lot code is an internal batch identifier that is generally not decodable from outside.
Date codes are also a counterfeit signal. Genuine production runs are tight, so a reel that mixes several unrelated date codes, or shows codes inconsistent with the package technology or the production window of the part, deserves scrutiny. That check belongs alongside the other tests in our guide on how to avoid counterfeit electronic components, and the codes should reconcile against the paperwork described in what a certificate of conformance must contain.
Aluminium electrolytics: the one family with a real clock
Everything above is about solderability. Aluminium electrolytic capacitors are the exception, because the ageing is internal. Manufacturer application guidelines, Nichicon among them, state that leakage current in parts stored for more than two years may increase, and prescribe a voltage treatment: apply the rated voltage through a series resistor of approximately 1 kOhm.
Skip that step and the oxide film re-forms anyway, but it does so through a large uncontrolled surge current on first power-up, which can damage the capacitor or the surrounding circuit. This is the one case where "it is old, so treat it" is genuinely mandatory rather than a matter of policy.
What to write into the purchase order
A workable policy replaces a blanket age limit with a tiered one. Specify:
- A preferred date-code window, plus explicit language that older stock is acceptable with a solderability report rather than rejected outright.
- Solderability testing to J-STD-002 on stock beyond your chosen threshold, with the sample size stated.
- Dry-pack condition on moisture sensitive devices: sealed moisture barrier bag, desiccant, and a humidity indicator card reading, photographed at goods-in.
- A certificate of conformance that ties the specific lot and date codes to the shipment.
- For electrolytics, either evidence of re-forming or an explicit agreement that you will perform it.
This is the same discipline that applies when the part is no longer in production at all, which we cover in sourcing obsolete electronic components.
If you are the one holding the aged stock
Date code is one of the main price levers on surplus, but it is not the only one, and old stock in original sealed packaging with intact documentation is worth substantially more than the same parts loose in a bin. Our guides on who buys excess electronic components and how to vet them and how to sell excess electronic stock set out the fields a stock list needs and how to get a realistic offer.
The short version
Ask what fails, not how old it is. For almost every component the answer is solderability, which is testable for a modest cost per lot and does not justify scrapping inventory. For aluminium electrolytics the answer is the oxide layer, which needs re-forming after roughly two years. For anything in an opened moisture barrier bag the answer is moisture, and the clock is hours rather than years.
GlobX supplies European OEM and EMS buyers with traceable stock including hard-to-find and long-discontinued lines, with date codes and lot traceability stated up front. Send us your part numbers and we will come back with availability, date codes and documentation.
