B-Stage Material: Partially cured resin-glass cloth (pre-preg) for multilayer bonding.
Back Planes: Thick (0.125"-0.3") interconnection boards for plugging PCBs/ICs.
Ball Grid Array (BGA): Chip package with solder ball array connecting to PCB landing pads.
Blind Via: Plated hole connecting outer layer to internal layers (not through entire board).
BOM (Bill of Materials): List of components with designators / descriptions for PCB assembly.
CAD (Computer-Aided Design): Software for designing PCB layouts and signal routing.
CAF (Conductive Anodic Filament): Conductive growth causing shorts in laminate under DC bias/humidity.
Characteristic Impedance: Transmission line property (ohms) determined by trace/plane geometry.
Chip-on-Board (COB): Bare IC bonded directly to PCB and encapsulated with epoxy.
CTE (Coefficient of Thermal Expansion): Material expansion rate per °C change (ppm/°C).
Desmear: Removing drilling debris/epoxy residue from hole walls.
Dielectric Constant (Dk): Material property affecting signal speed/impedance (relative to vacuum).
Differential Signal: Data transmission via paired wires with opposite voltage states.
Delamination: Separation between PCB layers or copper/laminate interfaces.
Dry Film: UV-sensitive film laminated on copper for pattern transfer.
Electroless Plating: Autocatalytic metal deposition without external current (e.g., PTH).
Etch Factor: Ratio: vertical etch depth ÷ lateral undercut during copper removal.
Embedded Component: Passives/chip dies buried inside PCB layers to increase density.
Epoxy Smear: Resin melted onto inner layer copper during drilling.
Edge-Board Connector: Gold-plated contacts on board edge for removable connections.
Fab: Abbreviation for printed circuit board fabrication process.
Fabrication Drawing: Technical drawing defining hole locations, board dimensions, and materials.
Fiducial: Etched markers for optical alignment in SMT assembly.
Film Artwork: Circuit/solder mask pattern on photographic film.
Fine Line Design: PCB with 2-3 traces between pins (e.g., 2mil line width).
Fine Pitch: Component leads with spacing ≤0.05" (e.g., 0.2mm BGA).
Finger: Gold-plated edge connector contacts on PCB.
Flex Circuit: PCB made of thin flexible polymer material.
Flux: Chemical removing oxides to facilitate soldering.
Fused Coating: Metallurgically bonded tin/solder coating (e.g., HASL).
Gerber File: Standard format (RS-274X) controlling photoplotters.
Glass Transition Temperature (Tg):Polymer state-change temperature (e.g., FR4 Tg=170°C).
Grid: Orthogonal coordinate system for component placement.
Ground Plane: Continuous copper layer for circuit return/shielding.
GIL Grade MC3D: Glass-core laminate with low Dk/Df for RF applications.
Haloing: Laminate fracturing around drilled holes due to stress.
HDI (High Density Interconnect): Technology using microvias/fine lines (<100μm).
Heavy Copper PCB: Boards with >4oz (140μm) copper for power circuits.
Hole Breakout: Hole partially outside its target copper land area.
Hole Void: Unplated area exposing base material in PTH.
Hot Air Solder Leveling (HASL): Solder coating via molten dip + hot air leveling.
Image: Photographic pattern on film or PCB layers.
Impedance: AC resistance of transmission lines (Ω) at high frequency.
Inner Layer: Buried conductive layer in multilayer PCBs.
Inspection Overlay: Transparency film for visual PCB pattern verification.
Insulation Resistance: Electrical resistance between isolated conductors.
IPC: Global association setting PCB design/manufacturing standards.
ITAR: US regulations controlling defense electronics export.
Jumper Wire: Manual wire added to bypass original circuit paths.
Kerf: Rout path widening to accommodate board-attached hardware.
Keying Slot: Polarizing slot preventing reverse insertion into connectors.
Laminate: Partially cured resin-glass cloth (pre-preg) for multilayer bonding.
Land: Copper area for component attachment (synonym: pad).
Laser Direct Imaging (LDI): Laser exposure of photoresist without film intermediates.
Layer-to-Layer Spacing: Dielectric thickness between adjacent conductive layers.
LPI (Liquid Photo Imageable): Liquid UV-curable solder mask applied by coating.
Laminate Void: Absence of epoxy/glass in base material (critical defect).
Microvia: Laser-drilled via (diameter<6mil) connecting adjacent layers.
Mil: Unit of length: 0.001 inch (0.0254 mm).
Measling: White fiber separations at glass cloth weave intersections.
Metal Foil: Thin conductive sheet (e.g., copper) for circuit formation.
Micro Sectioning: Cross-section polishing for microscopic quality inspection.
Nail Heading: Flared inner-layer copper caused by drilling deformation.
Negative: Film artwork with transparent circuit patterns.
Net List: CAE-generated list of logically connected components.
Nomenclature: Component identifiers printed/jetted on PCB surface.
Nonfunctional Land: Isolated copper land unconnected to circuit patterns.
Outer Layer: Top/bottom conductive layers of a PCB.
Outgassing: Gas emission from PCBs during soldering/vacuum exposure.
Overhang: Conductor width increase from plating build-up or etching.
Oxide: Chemical roughening of inner-layer copper for bonding.
Pad: Copper area for component mounting (synonym: land).
Panel Plating: Electroplating entire panel surface including holes.
Plated-Through Hole (PTH): Metal-plated hole connecting circuit layers.
Pre-preg: B-stage resin-impregnated glass for multilayer bonding.
Photo-Resist: Light-sensitive material for pattern imaging.
Pitch: Center-to-center spacing of adjacent features.
Quality Control (QC): System ensuring PCBs meet design specifications.
Registration: Conformity between pattern layers' alignment accuracy.
Resin Smear: Epoxy transferred to copper during drilling.
Resist: Material protecting copper from etching/plating.
Reverse Image: Resist pattern exposing copper for plating.
Rigidflex: Hybrid PCB combining rigid and flexible sections.
Solder Mask: Ink coating preventing solder bridging on copper.
SMOBC: Solder Mask Over Bare Copper fabrication process.
Surface Mount Technology (SMT): Assembly process for leadless components.
Short Circuit: Abnormal low-resistance connection between conductors.
Stacked Vias: Vertically aligned microvias in HDI designs.
Subtractive Process: PCB fabrication by etching away unwanted copper.
Tg (Glass Transition Temperature): Polymer state-change temperature (°C).
Tented Via: Via completely covered by solder mask for insulation.
Test Coupon: Fabricated sample for verifying PCB quality parameters.
Trace: Common term for PCB copper conductors.
Two-Sided Board: PCB with conductive layers on both sides.
UV Cure: Polymer hardening via UV exposure (200-450nm) without solvent evaporation.
Underwriters Laboratory (UL): Global safety certification agency for consumer electronics.
Underwriters Symbol: Logo indicating UL certification compliance on products.
UV Curing Process: Instant material solidification using UV light to initiate polymerization.
Via: Plated through-hole connecting inner layers without component leads.
Void: Absence of material in localized areas (e.g., air bubbles in PTH).
Voltage Plane: Continuous copper layer distributing power in multilayer PCBs.
V-Score: V-shaped groove cut on panel for easier board separation post-assembly.
Wave Soldering: THT assembly process passing boards over flowing molten solder.
Wicking: Capillary action drawing chemicals into glass fibers around holes.
WIP (Work In Progress): Semi-finished products in manufacturing process before final QC.
Warpage: PCB deformation due to CTE mismatch or thermal stress.
X-Ray Inspection: Non-destructive testing for internal defects (e.g., BGA voids, layer alignment).
Young's Modules: Material stiffness measurement under tension/compression (unit: GPa).
Zero Defects Sampling: Lot rejection if any defect found in a statistical sample.
Zigzag Via: Offset microvias avoiding direct stacking to reduce stress concentration.
