3.7 Shipping, Traceability, and Returns

The manufacturing process does not end when the device passes its final test. It ends when the customer successfully deploys the unit. Between the factory floor and the end-user lies a hostile environment of vibration, temperature spikes, and electrostatic fields. If the packaging strategy is weak, you have wasted the entire manufacturing effort. Furthermore, the relationship with the product continues through its lifecycle via traceability data and the returns process (RMA). These are the systems that allow you to solve problems that occur months after the product has left your hands.

Packing: The Final Engineering Defense

Packaging is often dismissed as "cardboard and foam," but it is a strictly engineered component of the product. It has three specific functional requirements: Mechanical Protection, Environmental Sealing, and ESD Shielding.

1. ESD Shielding (The Bag Matters)

Not all plastic bags are safe for electronics.

• Pink Poly Bags: These are "Anti-Static" (Low Charging). They do not generate static, but they do not block external static fields.
• Metallized Shielding Bags: These are "Faraday Cages." They block external electricity.
• If you ship sensitive boards in pink poly bags → Then a static discharge from the shipping box can penetrate the bag and destroy the FETs on the board.
• Rule: Always use metallized shielding bags (silvery-grey) for exposed PCBAs.

2. Moisture Control

If a product travels by sea freight, it sits inside a humid container for weeks.

• The Physics: Temperature drops at night cause condensation inside the bag.
• Control: Include a Desiccant Pack (silica gel) and a Humidity Indicator Card (HIC).
• If the HIC spots turn pink → Then the product has been exposed to moisture and may require baking before use.

Traceability: The Digital Thread

Traceability is the ability to reconstruct the history of a specific unit using its Serial Number. It is your insurance policy against catastrophic liability.

Batch vs. Unit Traceability

• Level 1 (Batch): "This unit was built in August 2023."
  • Risk: If a bad reel of capacitors was used in August, you must recall every unit made that month.
• Level 2 (Unit): "Unit SN #999 contains Capacitor Reel #ABC and was soldered at 245˚C."
  • Benefit: You can isolate exactly which 50 units used the bad reel and recall only those.

The "Birth Certificate"

Every serial number in the database should have a linked record containing:

• Time and Date of Assembly.
• Test Results (Voltage readings, Pass/Fail logs).
• Component Lot Codes (for critical parts).
• Firmware Version loaded.

RMA (Return Material Authorization): The Feedback Loop

When a product fails in the field, the customer requests an RMA. For the sales team, this is a financial transaction (refund/replace). For the engineering team, this is a forensic investigation.

The "No Trouble Found" (NTF) Trap

The most dangerous return is one where you test it, and it works fine.

• If you label a return as NTF and ship it back → Then you have ignored a latent defect that will likely fail again.
• Engineering Reality: An NTF result usually means the test coverage is incomplete. The customer saw a failure; your test missed it.
• Action: Improve the test limits to catch the intermittent fault.

Root Cause Analysis (RCA)

You must find the physics of the failure. "Ideally," you should produce an 8D Report (8 Disciplines) or a "5 Whys" analysis.

• Observation: Capacitor C1 burned.
• Why? It saw 20V.
• Why? The voltage regulator failed.
• Why? The regulator overheated.
• Why? The heatsink was missing thermal paste.
• Root Cause: Missing process control at the thermal paste station.

Pro-Tip: Do not trust the customer's description of the failure. "It doesn't work" could mean anything from "dead battery" to "I dropped it in a lake." Always perform your own triage.

Final Checklist