2.5 Data logging & repair tickets

Manual and mixed-technology assembly processes—particularly THT insertion, wave soldering, and complex rework—naturally generate highly valuable quality data. This chapter outlines some recommended data logging practices and introduces the Repair Ticket system. This thoughtful system helps ensure that every defect is comfortably contained, resolved, and gently traced back to its root cause (such as a design opportunity, a material variation, or a process drift), clearing the path for systematic and auditable process improvements.

Traceability in manual processes

The electronic traveler within the Manufacturing Execution System (MES) acts as the definitive record of the assembly’s journey. It is highly valuable to capture specific data points for every manual and automated process step along the way. This data forms the supportive foundation needed for complex repairs and fuels insightful Corrective and Preventive Action (CAPA) investigations.

Important record elements (per serial number)

• Identity & Context: The specific Product/Revision, the unique Serial Number (SN), and the associated Work Order (WO).
• Genealogy: The PCB lot code, specific THT component lot codes (which are especially helpful for tracking connectors), and the Pallet ID (if applicable).
• Process Parameters: The specific Wave/Selective Recipe ID used, the measured Top-Side Temperature achieved during preheat, and the designated manual assembly station ID.
• Inspection Linkage: Clear, direct references tying back to AXI/AOI inspection results and Visual Inspection (VI) sign-offs.
• Rework History: The Repair Ticket ID, the specific Defect Code, the Attempt Count, clear identifiers for any replaced parts, and a running log of Thermal Cycles (highly recommended for riskier components like BGAs).

Standardized defect codes

Subjective or vague defect descriptions (like “broken” or “bad”) are generally unhelpful for engineering analysis. Defect codes should ideally be granular enough to pinpoint the specific failing process or design characteristic. Defects generally fall into three comfortable categories: Preparation, Soldering, and Rework.

Category	Defect Code	Symptom and Probable Root Cause	Typical Process Owner
Preparation	FLUX-STARVED	Inadequate flux coverage observed prior to the wave/selective solder pass.	Fluxing / Preheat Engineering
	THERMAL-SHOCK	Component cracking (such as ceramic capacitors) likely due to an excessive ∆T rate.	Pre-heat / Profiling Engineering
Soldering	THT-INCOMPLETE-FILL	Insufficient top-side barrel fill. Frequently pointing to an improper THT hole/lead ratio or inadequate heat transfer.	Process Engineering / DFM
	THT-BRIDGE	A solder bridge between adjacent THT pins. Often relates to an unfavorable wave exit angle or occasionally missing solder thieves.	Wave / Selective Setup
	THT-ICICLE	Sharp solder peaks left on pins, nicely indicating a struggle with solder peel-back or drainage control.	Wave / Selective Setup
Rework	PAD-LIFT	Damage to the copper pad or trace occurring during manual touch-up or component extraction.	Rework Technician / Tooling
	HIP-REWORK	A Head-in-Pillow defect formally identified during a BGA rework reflow cycle.	Rework Profile Engineering

Guideline: It is best practice to log every failure using an officially approved, controlled code. Free-text fields are wonderful for providing additional contextual details, but they are most helpful when used alongside—rather than replacing—the official defect code.

Rework flow and traceability control

When a unit happens to gently fail inspection (whether caught via AOI or a diligent VI operator), the MES typically initiates a quarantine sequence to support a clear, helpful audit trail.

1. Ticket Generation (Failure): The unit is smoothly scanned into a Quarantine (NG-QUAR) status. The system generates a Repair Ticket, thoughtfully linking the Defect Code to the Operator ID who identified it.
2. Rework Action: A certified Repair Technician claims the ticket and is encouraged to log:
   • The specific Standard Work Instruction (SWI) referenced (for example, an IPC-7711/7721 trace repair procedure).
   • The Rework Tool/Profile ID (closely monitored when performing BGA/QFN hot-air reflows).
   • The Lot and Date Code of any fresh replacement components used (updating the Genealogy).
3. Attempt Tracking: The system usually auto-increments the Attempt Count each time a thermal rework cycle is applied to a specific component or board site. This gently enforces the maximum allowable thermal cycle limit (such as protecting a BGA from exceeding 2 allowed reflow attempts).
4. Verification Routing: Following the repair, the MES typically guides the unit through a re-inspection route. The unit should successfully pass the original failing gate (e.g. VI re-inspection or an FCT check) before its status comfortably returns to PASS.

Guideline: A reliable rule of thumb is that a component or board should generally not leave the rework area until its attempt count has been logged and it has successfully passed the system’s guided verification step.

Metrics for process improvement

The data we carefully log is utilized to calculate Key Performance Indicators (KPIs) that elegantly guide CAPA initiatives and help us reduce the Cost of Poor Quality (CoPQ).

• First Pass Yield (FPY): A wonderful primary metric for evaluating overall process stability and capability.
• Mean Time To Repair (MTTR): Helps track the general efficiency of the repair process, often segmented by defect code and technician to highlight training opportunities.
• Pareto Analysis: High-frequency defect codes are often analyzed weekly. Persistent challenges like THT-INCOMPLETE-FILL generally point us toward a DFM opportunity or a baseline process setup error, rather than isolated operator difficulties.
• Supplier Quality Triggers: Rework materials and replacement part lots are tracked. Clearly linking specific defect codes to a material lot can automatically trigger a helpful Supplier Corrective Action Request (SCAR).

Final Checkout: Data logging & repair tickets

Focus Area	Expectation	Benefit to the Process
Process Genealogy	Pallet ID, Wave/Selective Recipe ID, and Top-Side Temp are comfortably logged per SN.	Ensures every assembly can be traced smoothly back to the specific machine parameters used that day.
Defect Logging	Failures are logged with a standardized, granular code (such as THT-INCOMPLETE-FILL).	Ensures our defect data accurately and supportively informs the correct process owner (e.g. DFM vs. Process Engineering).
Thermal Cycle Limits	The Attempt Count is logged per site for higher-risk components (like BGAs/QFNs).	Validates that the total attempt count remains safely within the board’s maximum thermal cycle limit (e.g. ≤ 2 reflows).
Verification Routing	The unit successfully re-passes its original failing gate (e.g. VI or FCT) post-repair.	MES logic thoughtfully enforces the re-inspection sequence before a PASS status is granted.
Component Genealogy	Lot codes for all replacement parts are scanned and added to the SN history.	Maintains a clean, legally auditable record of the exact components traveling with the shipped assembly.