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4.3 What to Encode & How

Date/lot, line, BOM rev, SN; 1D vs 2D (GS1/ISO), human-readable, error correction.

Barcodes and 2D marks are the contract between the hardware on your bench and the data in your systems. The essentials are small but powerful: SN (serial number), BOM rev (bill-of-materials revision), and WO/date (work order or build date) so issues get isolated, not broadcast. Choose the right language for the mark—1D for distance scanning on rails and boxes, 2D (DataMatrix/QR with error correction) on the PCB—using GS1/ISO (global coding standards) when customers expect consistent parsing. Always pair machine code with a human-readable line so audits and debug don’t stall. Add a verify gate so print/laser marks are graded and reprinted if needed, then link every scan to MES/ERP (manufacturing/execution and enterprise systems) so genealogy stays complete. Pick only what earns its keep, encode it cleanly, and the label becomes a precise pointer to truth.

4.3.1 The data dictionary (what every code should carry)

Pick the smallest set that meets your traceability level (from 4.1) and customer/contract needs, then lock it in your Labeling & Traceability spec in the Golden Data Pack.

Core fields (most builds)

  • SN (serial number) — unique per unit (or panel ID if lot-level).
  • BOM Rev / Config ID — exposes which bill-of-materials revision the unit matches. Many customers require this on the visible label.
  • Work order / Lot / Date code — lets you quarantine precisely when needed.
  • Line / Station / Shift (compressed) — helps triage escapes fast.

Optional fields (add only if they earn their keep)

  • Variant / Feature flags (if one PCB serves multiple SKUs).
  • Regulatory or customer IDs (if contracts dictate).
  • Checksum or internal record key used to join with MES/ERP.

4.3.2 1D vs 2D (and which standards to speak)

1D barcodes (Code 128, etc.) are great for long, scannable strings and line-of-travel readers on rails and boxes.
2D codes (DataMatrix, QR) pack more data into less space and survive damage thanks to built-in error correction. Use them on the PCB when space is tight. Choose a GS1/ISO flavor when customers want global consistency. Put the choice (1D vs 2D, symbology, field order) in your label spec so scanners and MES parse it the same way.

Rules of thumb

  • Prefer DataMatrix/QR on the PCB for compact, durable unit IDs; keep Code 128 for cartons/pack-out where space is abundant.
  • Keep a quiet zone around every code and size modules for your cameras; verify readability in your scanning step (4.5).

4.3.3 Human-readable lines (for eyes and audits)

Always pair machine codes with a human-readable string (SN and minimal context like WO/Rev). It saves time in debug and still passes audits when a scanner fails. Put formatting examples in the spec and keep them consistent with what MES expects.

4.3.4 Error correction & verification (don’t skip this)

  • 2D codes include error correction by design; pick a level that tolerates your real world (solder splatter, cleaning, coat glare).
  • Add a verify step to your route: print/laser → scan to grade → apply/accept. Failures block WIP and open a reprint flow; successes write the record via API so there’s no “shadow spreadsheet.” (Details in 4.5.)

4.3.5 Where each code lives (and why)

  • Panel rail: big 1D or 2D for upstream/downstream station scans.
  • PCB (unit): compact 2D (SN + Rev + WO/Date) in a consistent corner with high contrast (from 4.2).
  • Box/pack-out: customer-facing 1D/2D per contract; mirror core fields and include shipping IDs. Tie all of them back to the same record in MES/ERP.

4.3.6 Put it in writing (spec template)

Your Labeling & Traceability spec should state:

  • Symbologies allowed (1D/2D; GS1/ISO where required) and data field order/lengths.
  • Human-readable format and fonts.
  • Placement (rail vs PCB vs box) and minimum clearances/quiet zones.
  • Verification step (scanner grade threshold, reprint flow) and API mapping to MES/ERP objects.



Bottom line: encode the minimum fields that let you isolate risk fast—SN, BOM rev, and WO/date—wrap them in the right symbology (1D for distance, 2D for density + error correction), keep a human-readable backup, and wire the whole thing to MES/ERP. That’s how marks become genealogy, not just ink.   


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