3.1 Traceability standards (IPC-1782)

Traceability is not an archive of what happened; it is the active defense against liability. In the event of a field failure, your ability to surgically recall only the affected units—rather than the entire month’s production—determines whether the recall costs $50,000 or $5,000,000.

We adopt IPC-1782 (Standard for Manufacturing and Supply Chain Traceability of Electronic Products) as the architectural baseline.

The four levels of traceability

It is unnecessary to apply “Nuclear Grade” traceability to an inexpensive consumable like a cable tie. Balance the risk against the cost using the IPC-1782 hierarchy. It is best practice to define the appropriate traceability level for every item on the BOM.

Level 1 (basic): lot/batch traceability

• Target: Passives (Resistors, Capacitors), Mechanicals (Screws, Housings).
• Record: “Lot A123 was used on Line 1 between 08:00 and 12:00.”

Level 2 (process): sequence traceability

• Target: PCBs, Standard ICs.
• Record: “Unit SN:123 passed Solder Paste Inspection at 09:05.”

Level 3 (component): serialized matching

• Target: High-value silicon (CPU, FPGA), Wireless Modules, Batteries.
• Record: “Child SN:ABC was placed on Parent SN:123 at Ref Des U4.”

Level 4 (parametric): process data

• Target: Safety-critical joints, Torque specs, Press-fit force.
• Record: “Screw J1 tightened to 4.5Nm with angle 12°.”

Minimum viable record (the data payload)

For every production event, the MES records a transaction containing these five immutable dimensions. If any of these dimensions are missing, the resulting record may be considered legally void or insufficient for a targeted recall.

1. Who (actor)

• Field: User_ID
• Requirement: This must map to a specific human operator or a defined service account. Generic or shared accounts like “Admin” should not be used for production transactions.

2. What (subject)

• Field: Unit_Serial_Number (The Parent) + Component_Lot_Or_SN (The Child).
• Requirement: The Parent SN is the Primary Key of the Genealogy Tree.

3. Where (location)

• Field: Resource_ID (Machine) + Slot/Feeder_ID.
• Requirement: Granularity must match the risk. Knowing it was “On the SMT Line” is insufficient; we must know it was “Feeder Slot 4, Nozzle 2.”

4. When (timestamp)

• Field: UTC_Timestamp.
• Requirement: Synchronized via NTP (See Chapter 2.4). Resolution: Milliseconds (YYYY-MM-DD HH:MM:SS.ms).

5. How (context)

• Field: Process_Outcome (Pass/Fail) + Parametric_Data (Volts, Temp, Torque).
• Requirement: Link to the specific Recipe_ID used.

The linkage keys

The database schema must enforce referential integrity. A collection of logs is not traceability; a Linked Graph is traceability.

• The Golden Thread: Every child component record must have a Parent_ID field pointing to the PCBA or Sub-assembly.
• The Work Order Bridge: Every Parent_ID must link to a Work_Order_ID. This connects the physical unit to the financial ERP record.
• The Material Bridge: Every Component_Lot must link to a Goods_Receipt_ID. This connects the shop floor usage back to the Supplier Invoice.

Validation logic

• When Component X is scanned, the system should verify whether Component X is a valid substitute or primary part for the current BOM.
• When the component is validated, the system creates the linkage record (e.g. integrating the Parent, Child, and Time into the Genealogy table).

Retention requirements (business rules)

The retention period is dictated by the product class and liability profile, not by disk space.

• Consumer Class: Warranty Period + 1 Year.
• Industrial/Medical: Product Lifecycle + 10 Years (Statute of Repose).
• Aerospace/Automotive: Perpetual (Life of Vehicle).

Rule: The MES should be configured to prevent any manual deletion of records that have not yet met their defined retention policy.

Final Checkout: Traceability standards (IPC-1782)

Category	Metric / Control	Threshold / Rule
Granularity	IPC Level	All Critical Components (CPU, Battery) = Level 3 (Serialized).
Integrity	The 5 Dimensions	Records drop if Who, What, Where, When, or How is missing.
Time	Sync	Timestamps must be UTC and NTP synced.
Linkage	Graph Check	100% of Serial Numbers link to a specific Work Order.
Suppliers	Inbound	No Lot enters the floor without a documented Date_Code and Manufacturer record.
Audit	Retrieve Time	A “Reverse Genealogy” (Component → Finished Goods) query executes in < 5 minutes.