PCB Glossary

Using capacitors to pass AC signals while blocking DC between circuits.

Automotive stress test qualification for integrated circuits, with temperature grading from -50°C to +150°C.

Automotive stress test qualification for passive components including resistors, capacitors, and inductors.

The copper pad area surrounding a drilled hole, critical for reliable connections.

PCB structure that radiates or receives electromagnetic energy.

HDI technology where all layers can interconnect with micro-vias, without traditional through-holes.

Machine vision system that inspects PCBs for defects by comparing images against reference designs.

Aerospace standard for counterfeit electronic parts avoidance, detection, and mitigation.

Aerospace quality management standard required by FAA, DoD, NASA, and major aerospace OEMs.

Ratio of hole depth to diameter, affecting plating quality in through-holes and vias.

Isola's thermoset alternative to PTFE for automotive radar at 77 GHz.

Removing unused via stub portions to reduce signal integrity issues at high frequencies.

Fracture in via plating wall caused by thermal cycling stress.

Minimum curve radius for flex circuits without damaging conductors or base material.

Surface-mount package with solder balls arranged in a grid pattern on the underside.

Process of removing old solder balls from a BGA and attaching new ones for reuse or repair.

Via connecting an outer layer to one or more inner layers without going through the entire board.

Test methodology using on-chip logic to verify connections without physical probe access.

PCB flatness deviations measured as warpage, critical for surface-mount assembly.

Differential traces stacked vertically on adjacent layers rather than side-by-side.

High-performance laminate material with excellent thermal stability and low dielectric constant.

Process of adding layers to a core through sequential lamination in HDI fabrication.

Via connecting inner layers without reaching either outer surface.

Software for designing PCB layouts, schematics, and generating manufacturing files.

Electrochemical failure mode where copper filaments grow along glass fibers.

Software that converts PCB design data into manufacturing instructions.

Half-holes at PCB edges that form solderable connections for module attachment.

Base material for PCB fabrication - laminate with copper foil bonded to one or both sides.

Inorganic substrate material offering superior thermal and electrical properties for demanding applications.

The impedance a transmission line presents to a signal, determined by geometry and materials.

Minimum spacing between conductive features, determined by voltage and manufacturing limits.

Surface microstrip covered with solder mask, lowering impedance by 2-3 ohms.

Signal component present equally on both lines of a differential pair.

Meeting regulatory and industry standard requirements for electronics.

Regulations requiring disclosure of tin, tantalum, tungsten, and gold (3TG) sourcing from conflict regions.

Thin protective film applied to assembled PCBs to shield against environmental hazards.

PCB traces designed and manufactured to a specific impedance value with tolerance.

Transmission line with signal trace flanked by ground on the same layer.

Electrochemical deposition of copper to build up trace thickness and plate hole walls.

Large area of copper filling unused space on a PCB layer, typically connected to ground or power.

Copper thickness specified as weight per square foot, where 1 oz = 35 µm (1.4 mil).

Rigid laminate with copper on both sides, the structural building block of multilayer PCBs.

Flexible polyimide film laminated over flex circuit traces instead of solder mask.

Shortest distance between conductors measured along the insulating surface, not through air.

Mesh pattern ground plane used in flex circuits to improve flexibility.

Unwanted coupling of signals between adjacent traces.

IC package where the package size is no more than 1.2x the die size.

Rate at which a material expands when heated, measured in ppm/°C.

Maximum current a trace can carry without excessive temperature rise.

Providing local energy storage to supply transient current demands from ICs.

Process of separating individual PCBs from a manufacturing panel after assembly.

Manufacturing constraints encoded in CAD tools to ensure producible designs.

Measure of signal energy lost as heat in a dielectric material, also called loss tangent.

Design practices that ensure a PCB can be manufactured reliably and cost-effectively.

Electrically insulating material between conductive layers in a PCB.

Ground-signal-signal-ground configuration combining differential and coplanar benefits.

Impedance seen between the two traces of a differential pair, approximately 2x odd-mode.

Two traces carrying complementary signals, providing noise immunity for high-speed signals.

Measure of a material's ability to store electrical energy, affecting signal speed and impedance.

Automated verification that a PCB design meets manufacturing constraints.

Creating holes in PCBs mechanically or with lasers for vias and through-holes.

Two signal layers between outer ground planes, typically routed orthogonally.

Major supplier of specialty PCB materials including Pyralux flex materials and Interra high-Dk laminates.

Copper plating on PCB edges for grounding, shielding, or electrical contact.

Two traces side-by-side on same layer with controlled gap spacing.

Chemical deposition of metal without external electrical current, for uniform coverage.

Metal deposition using electric current, building up copper thickness on PCB features.

Capacitance created in PCB inner layers using high-Dk dielectric materials.

Passive or active device fabricated or placed within PCB inner layers.

Trace buried in dielectric with single reference plane below, not between two planes.

Resistor fabricated directly into PCB inner layers using resistive foil or paste.

Ability of equipment to function without causing or being affected by EMI.

Unwanted electromagnetic energy that can disturb electronic equipment operation.

Three-layer surface finish adding palladium for improved wire bonding and corrosion resistance.

Surface finish with nickel barrier and thin gold layer, providing flat pads and good shelf life.

Routing signals out from under BGA and CSP components to reach vias or traces.

Standard for establishing ESD control programs protecting sensitive electronics during handling.

Chemical removal of unwanted copper to define traces and features.

Impedance seen by each trace in a coupled pair when driven with identical signals.

Routing from component pads to vias that connect to other layers.

High-capacitance laminate material for embedded capacitance layers.

Inductive component that absorbs high-frequency noise while passing DC and low frequencies.

Impedance variation caused by periodic glass/resin structure in PCB laminates.

Reference mark on a PCB used by pick-and-place machines for alignment.

PCB built on flexible polyimide substrate that can bend and flex.

Die mounting with the active side facing down, connected via solder bumps.

Chemical agent that cleans surfaces and promotes solder wetting during soldering.

Electrical test method using moving probes for prototype and low-volume testing.

The copper pad pattern on a PCB that matches a component's physical package.

Standard glass-reinforced epoxy laminate used in most PCBs.

Isola's low-loss high-Tg FR-4 variant with improved signal integrity over standard 370HR.

Testing an assembled PCB by powering it and verifying it performs its intended function.

Coplanar waveguide with additional ground plane on opposite side of substrate.

Standard file format for PCB manufacturing data, describing copper layers, solder mask, and silkscreen.

Specification of fiberglass weave pattern and weight used in laminate reinforcement.

Continuous copper layer providing current return path and reference for signals.

PCB materials without chlorine, bromine, and other halogenated flame retardants.

Surface finish where boards are dipped in molten solder then leveled with hot air knives.

RoHS-compliant HASL finish using lead-free solder alloys instead of traditional tin-lead.

PCB technology using micro-vias and fine lines to achieve higher wiring density.

Materials with dielectric constant significantly above FR-4, used for size reduction or embedded capacitance.

Signal frequencies or edge rates where transmission line effects and signal integrity matter.

Laminate with elevated glass transition temperature for lead-free assembly and thermal stress.

Ultra-smooth copper foil with <2 µm surface roughness for high-speed signal integrity.

Rogers' thermoset laminate combining ceramic filler with woven glass, balancing RF performance and processability.

Isola's workhorse low-loss laminate for high-speed digital designs up to 56 Gbps.

Automotive industry quality standard with requirements for defect prevention and supply chain traceability.

Electrical test using a bed-of-nails fixture to verify component presence and values.

Thin gold layer deposited by chemical displacement reaction, used in surface finishes.

Opposition to alternating current flow, measured in ohms, critical for high-speed signal integrity.

Manufacturing to specified characteristic impedance, typically ±10% tolerance.

Signal power lost as it travels through a PCB transmission line.

Global trade association that develops standards for electronics manufacturing.

Quality and reliability classification system for PCBs (Class 1, 2, or 3).

IPC standard classification for dedicated service electronic products.

IPC standard classification for high-reliability electronic products.

Foundational PCB design standard covering conductor spacing, trace width, via structures, and thermal management.

Design standard for flexible and rigid-flex PCBs, covering bend radius, pad placement, and stiffener design.

Design standard for HDI boards with microvias, fine lines, and high-density interconnects.

XML-based data format that consolidates all PCB manufacturing data into a single intelligent file.

Specification for PCB base materials with 70+ slash sheets defining laminate properties.

Qualification and performance specification for rigid PCB fabrication, covering quality requirements by class.

Qualification and performance specification for flexible and rigid-flex PCBs.

Qualification specification for high-frequency PCBs used in RF, microwave, and millimeter-wave applications.

Comprehensive procedural guide for reworking and repairing PCB assemblies.

Visual acceptance standard for bare PCB quality with photographs of target, acceptable, and nonconforming conditions.

The electronics industry's most widely used inspection standard for assembled PCBs and solder joints.

Data format standard for transmitting bare board electrical test information.

Quality management standard specifically for medical device supply chains with strict traceability requirements.

Environmental management certification for proper handling of chemicals, wastewater, and energy.

Fundamental quality management certification ensuring consistent processes and continuous improvement.

Major PCB laminate manufacturer known for FR-4 and high-speed materials.

Taiwanese laminate manufacturer with strong high-speed and halogen-free product lines.

Global standard for soldering materials, methods, and acceptance criteria in electronics assembly.

DuPont's polyimide film brand, the standard base material for flex circuits.

Hong Kong-based manufacturer and the world's largest producer of copper-clad laminates.

Cured copper-clad material forming the rigid base layers of a PCB.

Bonding PCB layers together with heat and pressure to form a solid multilayer structure.

Using focused laser energy to create micro-vias in PCB layers.

Number of copper layers in a multilayer PCB.

Soldering materials and processes without lead, required for RoHS compliance.

Ratio of energy lost to energy stored in a dielectric, equals dissipation factor.

Package or substrate containing multiple integrated circuits in a single unit.

Panasonic's high-speed laminate series, the industry standard for 10-112 Gbps digital applications.

PCB with metal base (aluminum or copper) for superior thermal dissipation.

Laser-drilled via ≤150 µm diameter, typically connecting adjacent layers in HDI PCBs.

Cross-sectional sample of PCB features for quality inspection and analysis.

Transmission line with a trace on the outer layer referenced to a ground plane below.

RF signals from ~300 MHz to ~300 GHz, requiring specialized PCB materials.

Current DoD performance specification for military PCBs with Qualified Manufacturers List program.

Legacy military specification for rigid PCBs, still required for some existing military programs.

PCB with three or more copper layers bonded together with dielectric.

Drilled hole without copper plating, used for mounting hardware or component clearance.

Intelligent CAD-to-CAM data format containing complete PCB manufacturing information.

Impedance seen by each trace in a differential pair when driven differentially.

Trace between two reference planes but closer to one than the other.

Resistive foil material for creating embedded resistors in PCBs.

Water-based organic coating that protects copper from oxidation until soldering.

Copper area for component attachment or via connection.

Frame of waste material around a PCB panel that holds boards together during manufacturing.

Arranging multiple PCBs on a larger panel for efficient manufacturing.

Board with conductive traces that mechanically supports and electrically connects electronic components.

Complete system delivering power from supply to ICs, including planes and decoupling.

Automated machine that places surface-mount components onto PCB pads.

Center-to-center spacing between adjacent component leads or pads.

Transformer using PCB windings instead of wound wire, enabling low-profile designs.

Electrochemical deposition of copper or other metals onto PCB surfaces and hole walls.

High-temperature polymer used as flexible PCB substrate and high-reliability rigid laminate.

Dedicated copper layer for power distribution to components.

Pre-impregnated fiberglass cloth that bonds layers together during lamination.

Low-loss fluoropolymer material used in RF and microwave PCBs, commonly known as Teflon.

Drilled hole with copper plating providing electrical connection between layers.

Alternative term for PCB, emphasizing the wiring interconnect function.

DuPont's dominant flex circuit material family based on Kapton polyimide.

Leadless surface-mount package with contacts on the bottom and exposed thermal pad.

Surface-mount IC package with leads extending from all four sides.

Propagation mode where fields are approximately but not purely transverse.

Copper foil pre-coated with resin, used for HDI build-up layers.

EU chemical regulation with 200+ restricted substances, broader scope than RoHS.

Signal energy bouncing back from impedance discontinuities in a transmission line.

Soldering process where paste is melted in an oven to attach SMT components.

Heated chamber that melts solder paste to form permanent solder joints.

Assembly process where solder paste melts in an oven to attach surface-mount components.

The probability that a PCB performs its intended function over its design lifetime.

Zone of pure resin between tightly-spaced traces formed during lamination.

Equipment for removing and replacing surface-mount components after initial assembly.

Electromagnetic signals from ~3 kHz to ~300 GHz, requiring special PCB design considerations.

Taconic's ceramic-filled PTFE laminate that processes like FR-4 for commercial microwave.

Wireless technology using electromagnetic fields to identify and track tags attached to objects.

PCB combining rigid board sections with flexible interconnect regions.

Rogers ceramic-filled PTFE laminate optimized for 77 GHz automotive radar.

Rogers hydrocarbon ceramic laminate that processes like FR-4 for RF applications to 10 GHz.

Rogers' most widely used RF laminate, the industry standard from 1 GHz to 77 GHz.

Major manufacturer of high-frequency PCB laminates, especially PTFE-based materials.

EU directive restricting lead, mercury, cadmium, and other hazardous materials in electronics.

The process of defining copper trace paths connecting component pins.

Rogers' gold-standard PTFE laminate with the lowest loss for aerospace and satellite applications.

Machine that applies solder paste to PCB pads through a stencil.

Automated soldering process for through-hole components on boards with SMT on the opposite side.

Multiple lamination cycles used to create buried vias and HDI structures.

Resistance of a thin film measured in ohms per square, independent of square size.

Major Chinese laminate manufacturer offering FR-4 through high-speed materials.

Conductive enclosure or layer blocking electromagnetic interference.

Quality of electrical signals, ensuring they arrive at receivers in usable condition.

Printed legend layer showing component designators, logos, and assembly markings.

Component designed to mount directly on the PCB surface without through-hole leads.

PCB construction where solder mask is applied directly over copper without a surface finish underneath.

Assembly method using automated placement of components on PCB surface pads.

Unintended solder connection between adjacent pads or traces.

The metallurgical bond connecting a component lead to a PCB pad.

Protective coating over copper traces, leaving pads exposed for soldering.

Mixture of powdered solder and flux used for SMT reflow assembly.

The ability of a surface to be wetted by molten solder, essential for reliable joints.

Minimum distance between copper features, determined by voltage and manufacturing capability.

Automated inspection of solder paste deposits before component placement.

Flattened fiberglass weave providing more uniform dielectric constant.

Micro-vias placed directly on top of each other through multiple layers.

The arrangement of copper layers, cores, and prepregs defining a PCB's structure.

Micro-vias offset from each other on successive layers to reduce filling requirements.

Thin metal sheet with apertures used to deposit solder paste onto PCB pads.

Transmission line with a trace on an inner layer sandwiched between two ground planes.

Protective coating applied to exposed copper to prevent oxidation and ensure solderability.

Trace on outer PCB layer with ground plane below and air above.

Trace centered exactly between two parallel ground planes.

Isola's ultra-low-loss laminate for 100 Gbps+ applications with performance stable to 100 GHz.

Manufacturer of high-frequency PCB laminates, particularly PTFE-based materials.

Change in resistance per degree of temperature change, expressed in ppm/°C.

Temperature at which PCB laminate begins to chemically break down.

Measurement technique for verifying controlled impedance by analyzing pulse reflections.

Gradual widening of a trace where it meets a pad or via to improve reliability.

Propagation mode where electric and magnetic fields are perpendicular to direction of travel.

Impedance-matching component at transmission line end to absorb signal and prevent reflections.

Sample structures on PCB panels for measuring impedance, plating thickness, and quality parameters.

Custom hardware interface that connects test equipment to a PCB for automated testing.

Temperature at which a laminate transitions from rigid to soft, affecting thermal reliability.

Material's ability to conduct heat, measured in W/m·K.

Repeated temperature fluctuations that stress PCB materials and solder joints over time.

Design techniques and materials for controlling heat in electronic assemblies.

Time-temperature curve for reflow soldering, optimized for solder paste and components.

Spoke pattern connecting a pad to a copper plane, balancing electrical connection with solderability.

Via designed to conduct heat from a component to inner planes or the opposite board surface.

Component attachment using leads inserted through holes and soldered on the opposite side.

Taconic's lowest-loss PTFE laminate for commercial satellite and radar applications.

Rogers ceramic-hydrocarbon thermoset series with Dk options from 3.27 to 12.85.

Assembly defect where a component stands on end due to unbalanced solder forces.

Fixtures, stencils, and equipment setup required for PCB fabrication and assembly.

Copper conductor on a PCB that carries electrical signals or power between components.

The width of a copper conductor, determining current capacity and impedance.

Controlled-impedance trace where signal wavelength is significant relative to trace length.

Safety certification organization that tests and certifies PCB flammability and safety.

UL safety standard for rigid and flexible PCBs covering flammability, thermal endurance, and electrical insulation.

Flammability classification for plastics, where V-0 is the standard for FR-4 PCB materials.

Epoxy material dispensed under BGAs and flip chips to improve thermal cycling reliability.

High-energy light used in PCB manufacturing for imaging, curing, and inspection.

Partial-depth cuts on PCB panels that allow boards to be snapped apart.

UK/Asia laminate manufacturer known for thermal management and halogen-free materials.

Plated hole connecting traces between PCB layers.

Completely filling vias with conductive or non-conductive material.

Filling vias with non-conductive epoxy to seal and planarize the surface.

Unused portion of through-hole via extending past the signal layer.

Covering vias with solder mask to protect from solder and contamination.

Via placed directly in a component pad, typically filled and planarized for SMD soldering.

Via placed in SMT pad, filled and plated flat for component mounting.

Effective ground reference formed equidistant between differentially-driven traces.

Assembly process where PCBs pass over a wave of molten solder for through-hole components.

EU directive for collection, recycling, and disposal of end-of-life electronics.

Non-destructive inspection using X-rays to view hidden solder joints under BGAs and QFNs.

Thermal expansion perpendicular to the PCB surface, critical for via reliability.