What a date code actually states
A date code identifies the manufacturing or seal date of a lot. Most commonly it is four digits: a two-digit year followed by a two-digit week, so 2432 reads as the 32nd week of 2024. Some manufacturers use two digits for the year and two letters for the month, others abbreviate to a single letter plus a digit, and some print the code only on the reel label rather than on the body.
The first practical rule is that the format is manufacturer-specific. Do not decode by pattern across brands — confirm the convention in the datasheet or the manufacturer's marking specification for that family.
Why it matters
- Age and shelf life. Solderability degrades over time, and parts stored outside controlled conditions degrade faster. Moisture-sensitive devices also have a floor life after the barrier bag is opened.
- Consistency within a lot. A single date code across a reel indicates one lot. Widely scattered codes on one reel suggest the parts have been re-batched.
- Traceability. If a failure appears in the field, the date code and batch number are what let you isolate which production run to investigate, and which shipments to quarantine.
- Suspect sources. Re-marked or reclaimed parts frequently carry implausible codes — a date in the future, a week that does not exist, or a code that does not match the revision printed elsewhere on the part.
Reading it in practice
- Locate the code on the package body, on the reel or tube label, and on the outer box. They should agree.
- Confirm the manufacturer's format for that part family before interpreting the digits.
- Compare the code against the purchase order and the certificate of conformance.
- Check one reel against another. Uniform codes within a reel and plausible progression across reels is what you want to see.
- Record the codes you receive. The record is the basis of any later traceability claim.
Warning signs worth acting on
- Mixed date codes within a single sealed reel or tube
- A date code later than the shipment date
- A code that conflicts with the part revision or the logo marking
- Label and body markings that disagree
- Codes that do not follow the manufacturer's format at all
- Parts presented as current production but marked several years old, with no explanation
Any single one of these is a reason to quarantine the lot and inspect further rather than to sort it out later on the line.
Batch numbers and lot traceability
A batch or lot number is a production identifier rather than a date. It is the field that ties a delivered part to a manufacturing run, and it is what makes a targeted recall possible instead of a blanket one. When you receive goods, record three things together: the part number with its full suffix, the date code, and the batch number. Without all three, a traceability claim is difficult to support later.
Turning it into a goods-in habit
Date codes cost nothing to check and catch problems that no functional test will find at incoming inspection. A short, consistent routine — locate, confirm the format, compare against documents, check consistency across the reel, record — takes minutes per line and produces the record you will want if something fails months later.
Checking incoming stock
At YILUDA TECH every listed part is 100% original, new and unused, with no refurbished or counterfeit material, held in stock at our Shenzhen warehouse and shipped worldwide by DHL, FedEx or UPS. Incoming inspection and traceability are available on request.
Send the full ordering code with quantity and destination and we will confirm availability, pricing and lead time. You can also browse the complete inventory, or start from a brand such as SK hynix, Littelfuse or Vishay.