Date codes: when component age matters

Start with the exact buyer requirement

A date code identifies a manufacturing period, but its format and location depend on the manufacturer and product family. State the acceptable date-code range, whether mixed lots are allowed and whether the requirement is driven by an approved BOM, assembly process or customer contract. Keep the full MPN — e.g. STM32F103C8T6 — with the date-code request. Do not assume that a newer code alone proves better quality. It is easy to get this exactly backwards — rejecting an older sealed reel while accepting a newer one from an opened bag. Age is one input; storage evidence is the other half of the decision.

• Keep the full MPN and manufacturer with the date-code request.
• Ask for the lot label and traceability evidence appropriate to the source.
• Specify whether a single lot is required before quotation.

Read the format from the exact manufacturer guide

For example, Microchip Technology’s PIC32CM SG00/GC00 marking guidance defines Y or YY as the last one or two year digits and WW as the manufacturing week. When the applicable guide specifies YYWW, the teaching example 2417 means a year ending in 24 and week 17; accompanying records must establish the full year. This is an explanation, not a date code for any Sourceics offer.

• Do not apply YYWW to every four-digit mark or manufacturer.
• Keep a clear photo of the complete top marking and original label.
• Check the exact device’s marking guide; ask the source to clarify shortened or ambiguous codes.

Do not confuse a date code with a lot number

Different batches can share a manufacturing week. Texas Instruments’ QML Class Q/V FAQ distinguishes the YYWW age-control code from the lot-date suffix used with the full part number for specific-lot traceability. That QML rule is not a universal marking scheme: request the actual lot identifier and supporting records for the offered material rather than treating the date code as proof of origin or authenticity.

Separate manufacturing age from storage condition

TI states that, for TI products such as LM2596S-3.3/NOPB, customer shelf life depends on materials, moisture sensitivity, moisture-barrier packaging, desiccant and storage conditions—not the manufacturing date code alone. This is manufacturer-specific guidance, not a blanket acceptance rule for every component or source.

Inspect the packaging evidence

For moisture-sensitive parts such as W25Q128JVSIQ, request the MSL classification and check the moisture-barrier bag, seal, humidity indicator and bag-seal date where applicable. Microchip guidance for its plastic-packaged devices recommends checking for a breached bag and the humidity indicator after opening. Any baking or requalification decision belongs to the manufacturer instructions and your assembly team. The MSL conversation often happens too late — after the reel is already on the production floor. Ask for the MSL classification and bag-seal evidence at the RFQ stage, while you still have leverage.

• Confirm whether the offered material remains in original sealed packing.
• Ask what evidence is available for storage and repacking history.
• Escalate damaged or unsealed packing before committing to production use.

Make offers comparable in the RFQ

Write the acceptable date-code range, lot policy, MSL or packing requirements and evidence needed into the RFQ. Request the exact offered lot details before approval; do not infer a particular date code or condition from a public availability figure.

Frequently asked questions

Quick answers to the questions buyers ask most about date codes.

• Q: Does a newer date code mean better quality? A: Not by itself — storage conditions, moisture handling and packaging matter as much as manufacturing age.
• Q: Is the date code the same as the lot number? A: No — different batches can share a manufacturing week. Ask for the actual lot identifier and supporting records.
• Q: Can I read YYWW on any four-digit marking? A: No — marking formats are manufacturer-specific. Check the exact device's marking guide and ask the source about ambiguous codes.
• Q: The moisture-barrier bag arrived open — what now? A: Escalate before committing to production use: check the MSL classification and humidity indicator, and follow the manufacturer's baking guidance with your assembly team.