6.19 Critical Terminology for Manufacturing Process Control

The successful execution of high-reliability manufacturing requires a mandatory, shared lexicon that transcends department-specific jargon. Misinterpretation of key terms, acronyms, and metrics is a direct contributor to process variability and systemic non-conformance risk. This standardized glossary provides concise, objective definitions for the terminology critical to managing yield, quality metrics, and regulatory compliance, ensuring all engineering and management functions operate from a single, auditable set of definitions.

6.19.1 Standardized Acronyms and Technical Glossary

Definitions provide the critical context linking shop-floor activities to documented engineering specifications.

• A-610 (IPC-A-610): The definitive standard governing the visual acceptability criteria for electronic assemblies (workmanship standard).
• AOI: Automated Optical Inspection system utilizing cameras and algorithms for surface mount solder joint and component placement verification.
• AQL: Acceptable Quality Level. A statistical metric defining the maximum number of defectives permitted in a sampling plan for a lot to be considered acceptable.
• AXI: Automated X-ray Inspection. Non-destructive testing method for inspecting hidden solder joints (BGA, QFN) and verifying internal layer registration.
• AVL: Approved Vendor List. The mandatory registry of qualified suppliers for materials and components. Procurement outside this list is prohibited.
• BGA: Ball Grid Array. A high-density component package defined by an array of hidden solder spheres beneath the device body.
• BOM: Bill of Materials. The complete, controlled list of raw materials, parts, and quantities required for product assembly.
• CAPA: Corrective and Preventive Action. The formal, mandated process to identify, contain, and eliminate the root cause of systemic non-conformance.
• Class (1/2/3): IPC Workmanship Class. The classification that dictates the level of workmanship quality required. Class 2 is standard; Class 3 is mandatory for critical, high-reliability applications.
• CMC / Cpk: Capability Metrics. Statistical indices measuring how tightly and centered a process operates relative to specification limits. Mandatory for Statistical Process Control (SPC).
• CTQ: Critical-to-Quality. Any design or process requirement that directly impacts performance or reliability and must be controlled and measured.
• CTE: Coefficient of Thermal Expansion. The rate at which material dimensions change with temperature. Mismatches drive solder joint stress and warpage.
• DFx: Design for X. An encompassing set of engineering rules (e.g., Manufacturability, Assembly, Test) implemented to optimize design for high yield and low Cost of Poor Quality (COPQ).
• DPMO / PPM: Defects per Million Opportunities / Parts Per Million. Standardized metrics for quantifying defect rates and reporting process yield performance.
• ECN / ECO: Engineering Change Notice / Order. The controlled document dictating and approving formal changes to a product design, BOM, or documentation.
• EMC / EMI: Electromagnetic Compatibility / Interference. Control requirements that minimize noise generation and susceptibility. Often requires bonding to Protective Earth (PE).
• ENIG / OSP / HASL: Common PCB finish types that define the surface's solderability and shelf life. Governed by J-STD-003.
• ERP: Enterprise Resource Planning. The system managing core business processes, including procurement, inventory, and materials planning. Integrates with MES.
• ESD (S20.20): Electrostatic Discharge. The mandatory control program covering zones, grounding, personnel protective equipment, and audit standards.
• FPY: First Pass Yield. The percentage of units successfully passing a specific manufacturing or test stage the first time. A key Key Performance Indicator (KPI).
• Gage R&R: Gage Repeatability and Reproducibility. A study within MSA to quantify the variation contributed by the measurement system itself.
• Golden board/unit: The known-good reference sample used for fixture teaching, system setup, and process debug validation.
• Head-in-pillow: A BGA defect where the solder ball and solder paste fail to fully coalesce, forming a weak, unreliable joint. Requires AXI detection.
• Hipot: High Potential Test. A high-voltage safety test verifying the integrity of dielectric withstand voltage and insulation resistance (IR).
• ICT: In-Circuit Test. Automated electrical test utilizing a bed-of-nails fixture to measure components and net continuity on the PCB.
• IPC-7711/7721: The standard governing rework, repair, and modification of electronic assemblies. Rework tickets must cite the specific method ID.
• J-STD-001: The definitive standard governing the requirements for soldered electrical and electronic assemblies (process standard).
• Kitting: The process of accurately pulling and preparing all required components from inventory per the BOM for a specific work order. Kitting error is a major defect risk.
• Land pattern (IPC-7351): The standardized footprint geometry on the PCB pad designed to ensure optimal printing and reflow characteristics.
• Lean / 5S: A manufacturing philosophy focused on waste reduction and continuous improvement, incorporating 5S (Sort, Set, Shine, Standardize, Sustain) for workplace organization.
• MBB / HIC: Moisture Barrier Bag / Humidity Indicator Card. Required packaging for MSL components to prevent moisture absorption and subsequent defect risk during reflow.
• MES: Manufacturing Execution System. The core system controlling and documenting the execution of production, tracing Work In Process (WIP), and managing serialization.
• MSA: Measurement System Analysis. A required study to confirm the reliability and accuracy of measuring equipment.
• MSL: Moisture Sensitivity Level. The component classification (J-STD-033) that defines mandatory floor life and baking protocols to prevent popcorning during thermal processing.
• NCR: Non-Conformance Report. The formal document recording any material, component, or assembly found to be outside documented specifications.
• NPI: New Product Introduction. The controlled phase that manages the transition from prototype build to volume production, including mandatory First Article Inspection (FAI).
• OEE: Overall Equipment Effectiveness. The metric quantifying manufacturing efficiency: Availability x Performance x Quality.
• Poka-yoke: Mistake-proofing. Design or fixturing solutions (e.g., keys, interlocks) implemented to make it physically or functionally impossible to perform an action incorrectly.
• RCA: Root Cause Analysis. The systematic method used to determine the fundamental cause of a defect or failure, feeding directly into the CAPA process.
• SCAR: Supplier Corrective Action Request. A formal, documented ticket issued to a supplier detailing a quality issue and mandating corrective action.
• SIR: Surface Insulation Resistance. A test method (IPC-TM-650) used to assess the effectiveness of the cleaning process and potential risk of electrochemical migration.
• SMT / THT: Surface-Mount Technology / Through-Hole Technology. The two fundamental methods of component assembly.
• SPI: Solder Paste Inspection. A mandatory 3D volume measurement of printed paste applied to the board, performed before component placement.
• SPC: Statistical Process Control. The systematic use of control charts and metrics (Cp, Cpk) to detect process drift and prevent non-conformance.
• SWI: Standard Work Instruction. The documented, controlled procedures (often visual) providing step-by-step direction for a specific operation.
• TAL: Time Above Liquidus. The portion of the reflow thermal profile where the solder is in its liquid state. Duration is a critical process variable.
• TIM: Thermal Interface Material. Any material (e.g., pad, grease, paste) used to enhance thermal transfer between a heat-generating component and a sink.
• Torque map: The controlled document specifying the mandatory torque setpoints (and threadlocker grade) for all fasteners on an assembly.
• Traceability (IPC-1782): The mandatory capability to link a finished unit back to its constituent components, process steps, and test results via a database (MES).
• Void (BGA/thermal): Gas pockets trapped within a solder joint. The maximum allowable void area is a critical acceptance criterion verified by AXI.
• WIP: Work In Process. Units that have started production but are not yet complete, requiring continuous tracking by the MES.
• WHMA-A-620: The acceptability standard for cable and wire harness assemblies.

Final Checklist