1.1 The GDP Standard: Formats, Directory & Integrity

Production issues often begin with data ambiguity. When the engineering input data is fluid, subjective, or incomplete, the manufacturing output will be unpredictable.

The Golden Data Pack (GDP) is a deliberately controlled configuration item, not a casual collection of email attachments or a link to a live SharePoint folder. It represents a single, immutable snapshot of the product definition at one specific moment in time. When the GDP does not compile to a deterministic, repeatable state, the physical build should not start.

The Frozen Artifact Principle

The GDP must be treated like a compiled binary for the factory. It must be delivered as a single, version-controlled archive (.zip or .tar) carrying a unique hash.

The Rule of Immutability

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

• When an engineering change is required (even altering a single resistor value), a completely new GDP Revision (REV_A02) must be generated and released.
• When files are replaced “on the fly” via email or Slack, configuration integrity is broken, and warranty liability shifts back to the design engineer.

Directory Structure Standard

A standardized directory structure eliminates wasteful “treasure hunting” by CAM engineers. The GDP root directory should adhere to the following schema.

The Required Directory Layout:

/PROJECT_NAME_REV_XX/

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

├── 01_BOM/ (The Bill of Materials)

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

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

├── 04_SCHEMATICS/ (PDF format strictly for debug reference only)

└── 05_TEST_FIRMWARE/ (Binaries, Flashing instructions, Test specifications)

Pro-Tip: Burying files in deep sub-folders like ”…/Outputs/Job1/Gerbers/Final/For_Production” is prohibited. The hierarchy must be flattened to the core folders listed above.

Allowed Formats & Rejection Criteria

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

Fabrication Data (The PCB)

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

Assembly Data (The PCBA)

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

Intake Logic: When to Reject the Pack

• When the archive contains “mystery files” (e.g., “Old_Files_Ignore.zip”), the pack is rejected.
• When file names contain conflicting revision tags (e.g., the root folder indicates REV_B but the Gerber package indicates REV_A), the pack is rejected.
• When critical hardware layers (Paste, Silkscreen, Drill) are missing, the pack is rejected.

The Manifest: Proof of Origin

Every single 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 reliably prove what was built 12 months from now.

Mandatory Manifest Data Fields:

1. Package Revision: Must exactly match the archive filename.
2. Generation Date: ISO 8601 format (YYYY-MM-DD).
3. Author/Owner: The accountable Engineering point of contact.
4. EDA Tool Version: (e.g., Altium 23.1, KiCad 7.0). This is critical for debugging obscure polygon translation errors.
5. Master Checksum (SHA-256): (Highly Recommended) Cryptographically validates file integrity during cross-network transfer.

Final Checkout: The GDP standard: formats, directory & integrity

The Control Point	The Operational Requirement	The Go/No-Go Metric
Archive Format	Single contiguous .zip/.tar file.	Zero loose files or split email attachments.
Naming Convention	”Project_Revision_Date.zip”	Perfectly matches the internal PLM record.
Directory Structure	Standard 00-05 root folder layout.	Files are exactly located in correct sub-directories.
Fab Data	ODB++ OR Gerber + Drill + Netlist.	CAM software loads the entire stack with zero errors.
BOM Format	CSV/XLSX (Purely Machine Readable).	Zero PDF BOMs accepted.
Assembly Instructions	Formal EWI/SOP version control.	PDF or Word.
Mechanical Models	The exact chassis structure.	STEP or IGES files.
The GDP Itself	Single contiguous .zip/.tar file.	Zero loose unversioned files allowed.
Revision Sync	All files sync to one master Revision ID.	No mixed-revision packs (Rev A PCB + Rev B BOM).
The Manifest	README or Manifest file is present.	Contains Author, Date, and specific Tool Version.