1.2 The Bill of Materials (BOM) & Revision Control

The Bill of Materials is a relational database that drives procurement, logistics, and machine programming; it is never merely a spreadsheet. A flawed BOM is the single largest source of line-down events. This specification mandates a structure that enforces supply chain resilience and unambiguous component identification, treating the BOM as a locked configuration state rather than a fluid document.

Database Structure and Columns

The BOM must be machine-parsable. Merged cells, color-coding for data logic, and hidden rows are prohibited.

• Manufacturer Part Number (MPN): The primary key. Generic descriptions (e.g., "10k Resistor 0402") are rejected. The MPN must be the exact orderable part number (e.g., RC0402JR-0710KL).
• Reference Designator (RefDes): Must match the ECAD data exactly. Ranges (e.g., "R1-R5") are prohibited; delimiters must be used (e.g., "R1,R2,R3,R4,R5") to allow automated counting.
• Quantity: Must match the count of RefDes.
• DNP (Do Not Populate): Components intended to be omitted must remain in the BOM with a defined MPN but a Quantity of 0 or a specific "DNP" flag. Removing the line item entirely creates ambiguity regarding whether the omission was intentional or accidental.

Approved Vendor List (AVL) Management

Supply chain volatility requires flexibility. Passive components (Resistors, Capacitors) must define an "Open AVL" or list specific alternates.

• Primary Column: The preferred MPN.
• Alternate Columns: Validated substitutes (e.g., Yageo vs. Murata) that do not require Engineering Change Order (ECO) approval.
• Critical Parts: Components with unique footprints or characteristics (ICs, Connectors) must be flagged as "No Sub" to prevent unauthorized procurement substitutions.

Engineering Change Notice (ECN) Protocol

Once the Golden Data Pack is locked (Status: RELEASED), no changes can occur without a formal ECN.

• ECN Class 1 (Mandatory): Safety or functional failure. Immediate stop-work order. All WIP is quarantined.
• ECN Class 2 (Yield/Cost): Improvement to manufacturability. Implemented at the next logical break point (e.g., next PO).
• Revision Syntax: The Revision String (e.g., v 1.0) in the filename must increment with every ECN. The "Redline Document" highlighting the delta must accompany the new data pack.

Final Checklist