6.7 Shelf-Life, Lot Traceability & Recall Readiness

Traceability is your insurance policy against total disaster. When a supplier announces a recall for a specific capacitor lot, or when a solder joint fails in the field, you have two options: recall everything you built that year (bankruptcy risk), or surgically recall only the specific serial numbers built with that specific lot (manageable risk). The difference is granular data.

The Scope of Control

Do not track everything with equal intensity. Focus strict lot control on items that drive reliability or chemical expiry.

• Tier 1 (Mandatory Lot Control):
  • Active Components: ICs, Modules, Sensors (Date Code/Lot Code).
  • Process Chemicals: Solder Paste, Flux, Adhesives, Conformal Coating (Batch ID + Expiry).
  • Safety Critical: Batteries, Fuses, High-Voltage caps.
• Tier 2 (Batch Level): Passives (Resistors/Caps) from "A-Level" manufacturers.
• Tier 3 (Commodity): Standard hardware (screws, standoffs) – FIFO is usually sufficient unless aerospace/medical requirements dictate otherwise.

FEFO Logic (First Expired, First Out)

Move beyond FIFO (First In, First Out). For shelf-life sensitive materials, use FEFO.

• The Rule: The system must allocate stock based on the Expiration Date, not the Receipt Date.
• Scenario: You receive Batch A (Expires Jan 1st) today. You already have Batch B (Expires Feb 1st).
  • Action: System forces picking of Batch A first.
• Expiry Lockout: The ERP must hard-block picking of any lot where Current Date > Expiration Date. The warehouse scanner should display a "STOP – EXPIRED" error if an operator attempts to scan it.

Data Capture Points (The Chain of Custody)

Traceability breaks if a single link is missing.

1. At Receipt (The Input):
   • Record Manufacturer Lot Number and Date Code (DC) into the ERP batch record.
   • Record Expiration Date for chemicals.
   • Constraint: Do not mix two different lots in the same bin unless they are physically segregated and system-separated.
2. At Issue (The Link):
   • Scan the specific Lot Number against the Work Order (WO).
   • If issuing split reels → Then the system must record which split went to which WO.
3. On Line (The Consumption):
   • For SMT: The "Feeder Setup" validation must link the Reel ID to the Machine/Feeder slot.
   • For Chemicals: Operator scans the jar/cartridge ID before applying to the stencil or dispenser.

Shelf-Life Governance & Extension

Chemicals and solderability degrade with time. Rules must be based on physics, not convenience.

• Component Date Codes:
  • Standard Limit: 2 Years (typical).
  • If > 2 Years → Then Block. Requires "Solderability Test" (IPC/EIA/JEDEC standards) to extend. Visual inspection is not a test.
• Process Chemicals (Paste/Adhesives):
  • Strict Expiry: If the date passes, the flux is inactive or the polymer has cross-linked.
  • Disposal: Expired chemicals are Hazardous Waste. They must be moved to the "Doomed" zone immediately.
  • No "Gold Seal" Extensions: Do not extend solder paste life based on a "print test." The chemistry is compromised. Scrap it.

The Recall Drill (Validation)

Do not wait for a crisis to test your data. Perform a Mock Recall every 6 months.

• The Challenge: Pick a random Lot ID from a component received 6 months ago.
• The Clock: You have 4 hours.
• The Goal: Produce a report listing:
  1. Which Work Orders consumed this lot?
  2. Which Serial Numbers (finished goods) contain this lot?
  3. Where are those Serial Numbers now (WIP, Stock, or Shipped to Customer X)?
• Success Criteria: 100% accuracy within the time limit. If you cannot do this, your traceability is a myth.

Final Checklist