1.1 The GDP Standard: Formats, Directory & Integrity

Production failure begins with data ambiguity. If the input data is fluid, the manufacturing output will be random. The Golden Data Pack (GDP) is not a collection of email attachments or a shared folder link; it is a frozen configuration item. It represents a single, immutable snapshot of the product definition at a specific point in time. If the GDP does not compile to a deterministic state, the build must not start.

The Frozen Artifact Principle

Treat the GDP as a binary executable for the factory. It must be delivered as a single, version-controlled archive (ZIP or TAR) with a unique hash.

The Rule of Immutability:

Once a GDP revision (e.g., REV_A01) is released to the EMS, no file inside it may change.

• If a change is required (even a single resistor value) -> Then a new GDP Revision (REV_A02) must be generated.
• If files are replaced "on the fly" via email -> Then the configuration integrity is broken, and warranty liability shifts to the engineer.

Directory Structure Standard

A standardized directory structure eliminates "treasure hunting" by CAM engineers. The GDP root directory must strictly adhere to the following schema.

Required Directory Layout:

/PROJECT_NAME_REV_XX/

├── 00_MANIFEST/ (Traceability & Meta-data)

├── 01_BOM/ (Bill of Materials)

├── 02_FABRICATION/ (Gerbers, ODB++, Drill files, Stackup)

├── 03_ASSEMBLY/ (Pick & Place, Assembly Drawings, Stencil)

├── 04_SCHEMATICS/ (PDF reference only)

└── 05_TEST_FIRMWARE/ (Binaries, flashing instructions, test spec)

Pro-Tip: Do not bury files in sub-sub-folders like .../Outputs/Job1/Gerbers/Final/For_Production. Flatten the hierarchy to the primary folders listed above.

Allowed Formats & Rejection Criteria

The EMS intake process is a logic gate. Data must be machine-readable and unambiguous.

Fabrication Data (PCB)

• Preferred: ODB++ (.tgz) or IPC-2581 (.xml). These formats contain intelligent layer data, preventing stackup errors.
• Accepted: Gerber X2 / RS-274X. Must include NC Drill files (Excellon) and a Netlist (IPC-D-356) for electrical test validation.
• Rejected: Native CAD files only (e.g., .PcbDoc, .brd) without fabrication outputs. Native files introduce version dependency risks.

Assembly Data

• Required: Centroid/Pick-and-Place file (ASCII/CSV) containing: RefDes, X-Loc, Y-Loc, Rotation, Side (Top/Bottom).
• Required: BOM in structured CSV or Excel format.
• Rejected: PDF-only BOMs or scanned images.

Intake Logic: When to Reject

• If the archive contains "mystery zips" (e.g., Old_Files_Ignore.zip) -> Reject.
• If file names contain conflicting revision tags (e.g., folder says REV_B but Gerber says REV_A) -> Reject.
• If critical layers (Paste, Silk, Drill) are missing -> Reject.

The Manifest: Proof of Origin

Every GDP must contain a 00_MANIFEST/README.txt or manifest.json. This file acts as the birth certificate of the build configuration. Without it, production cannot prove what was built 12 months from now.

Manifest Data Fields:

1. Package Revision: Matches the archive filename.
2. Generation Date: ISO 8601 format (YYYY-MM-DD).
3. Author/Owner: Engineering point of contact.
4. EDA Tool Version: (e.g., Altium 23.1, KiCad 7.0). Critical for debugging translation errors.
5. Master Checksum (SHA-256): (Optional but recommended) Validates file integrity during transfer.

Final Checklist

Check	Requirement	Pass Metric
Archive Format	Single ZIP/TAR file.	No loose files or multiple attachments.
Naming Convention	Project_Revision_Date.zip	Matches internal PLM record.
Structure	Standard 00-05 folder layout.	Files are located in correct sub-directories.
Fab Data	ODB++ OR Gerber + Drill + Netlist.	CAM software loads with zero errors.
BOM Format	CSV/XLSX (Machine Readable).	No PDF BOMs.
Revisions	All files sync to one Revision ID.	No "Frankenstein" packs (Rev A PCB + Rev B BOM).
Manifest	README or Manifest present.	Contains Author, Date, Tool Version.