Printed Circuit Board Glossary

We have compiled an extensive list of industry terms that will help you understand the complexities of printed circuit boards. If you are looking for a specific term, just click on the appropriate letter to jump directly to that section.

 

A | B | C | D | E | F | G | H | I | J | K | L | M | N | P | R | S | T | U | V | W

A

Activating

A treatment that renders non-conductive material receptive to electroless deposition.

Active Components

Semiconductor devices, such as transistors and diodes, that can change its basic characteristics in a powered electrical circuit, such as amplifiers and rectifiers.

Additive Process

A process for obtaining conductive patterns by the selective deposition of conductive material on clad or unclad-based material.

Analog Circuit

An electrical circuit that provides a continuous quantitative output as a response from its input.

Annular Ring

The portion of conductive material completely surrounding a hole.

Array

A group of elements or circuits (or circuit boards) arranged in rows and columns on a base material.

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Artwork

An accurately scaled configuration used to produce the artwork master or production master.

Artwork Master

The photographic film or glass plate that embodies the image of the PCB pattern, usually on a 1:1 scale.

Aspect Ratio

A ratio of the PCB board thickness to the diameter of the smallest hole.

Assembly

A number of parts, subassemblies, or any combination thereof joined together.

Assembly File

A drawing describing the locations of components on a PCB.

Automated Test Equipment (ATE)

Equipment that automatically tests and analyzes functional parameters to evaluate performance of the tested electronic devices.

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B

Ball Grid Array (BGA)

A SMD package in which solder ball interconnects cover the bottom surface of the package.

Bare Board

An unpopulated PCB.

Barrel

The cylinder formed by plating through a drilled hole.

Base Copper

The thin copper foil portion of a copper-clad laminate for PCBs. It can be present on one or both sides of the board.

Base Copper Weight

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Base Material

The insulating material upon which a conductive pattern may be formed. It may be rigid or flexible or both. It may be a dielectric or insulated metal sheet.

Base Material Thickness

The thickness of the base material excluding metal foil or material deposited on the surface.

BBT

Bare Board Test.

Bed Of Nails Fixture

A test fixture consisting of a frame and a holder containing a field of spring-loaded pins that make electrical contact with a planar test object (i.e., a PCB).

Bill of materials (BOM)

A comprehensive listing of all subassemblies, components, and raw materials that go into a parent assembly, showing the quantity of each required to make the assembly.

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Bleeding

A condition in which a plated hole discharges process materials of solutions from voids and crevices.

Blind Via

A conductive surface hole that connects an outer layer with an inner layer of a multi layer board without penetrating the entire board.

Blister

A localized swelling and separation between any of the layers of a laminated base material, or between base material or conductive foil. It is a form of delamination.

Bond Strength

The force per unit area required to separate two adjacent layers of a board by a force perpendicular to the board surface.

Bow

The deviation from flatness of a board characterized by a roughly cylindrical or spherical curvature such that if the board is rectangular, its four corners are in the same plane.

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B-Stage Material

Sheet material impregnated with a resin cured to an intermediate stage (B-stage resin). PrePreg is the popular term.

B-Stage Resin

A thermosetting resin that is in an intermediate state of cure.

Built-In Self Test

An electrical testing method that allows the tested devices to test itself with specific added-on hardware.

Buried Via

A via hole that does not extend to the surface of a printed board.

Burr

A ridge left on the outside copper surface after drilling.

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C

CAD

Computer Aided Design.

CAM Files

The files used for manufacturing PCB including Gerber file, NC Drill file and Assembly Drawings.

CAM

Computer Aided Manufacturing.

Capacitance

The property of a system of conductors and dielectrics which permits storage of electricity when potential difference exists between conductors.

Ceramic Ball Grid Array (CBGA)

A ball grid array package with a ceramic substrate.

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Chamfer

A broken corner to eliminate an otherwise sharp edge. Chip: The individual circuit or component of a silicon wafer, the leadless form of an electronic component.

Chip-on-Board (COB)

A configuration in which a chip is directly attached to a printed circuit board or substrate by solder or conductive adhesives.

Circuitry Layer

A layer of a printed board containing conductors, including ground and voltage planes.

Clad Or Cladding

A relatively thin layer or sheet of metal foil that is bonded to a laminate core to form the base material for printed circuits.

Coating

A thin layer of material, conductive, magnetic or dielectric, deposited on a substance surface.

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Coefficient of Thermal Expansion (CTE)

The ratio of dimensional change of an object to the original dimension when temperature changes, expressed in %/ºC or ppm/ºC.

Component Hole

A hole used for the attachment and electrical connection of a component termination, including pin or wire to the circuit board.

Component Side

The side of the circuit board on which most of the components are mounted.

Conductor

A thin conductive area on a PCB surface or internal layer usually composed of lands (to which component leads are connected) and paths (traces).

Conductor Spacing

The distance between adjacent edges (not centerline to centerline) of isolated conductive patterns in a conductor layer.

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Conductor Thickness

The thickness of the conductor including all metallic coatings.

Conformal Coating

An insulating protective coating which conforms to the configuration of the object coated and is applied on the completed board assembly.

Connector Area

The portion of the circuit board that is used for providing electrical connections.

Contact Angle (Wetting Angle)

The angle between the contact surfaces of two objects when bonding. The contact angle is determined by the physical and chemical properties of these two materials.

Controlled Impedance

The matching of substrate material properties with trace dimensions and locations to create specific electric impedance as seen by a signal on the trace.

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Copper Foil (Base Copper Weight)

Coated copper layer on the board. It can either be characterized by weight or thickness of the coated copper layer. For instance, 0.5, 1 and 2 ounces per square foot are equivalent to 18, 35 and 70 um-thick copper layers.

Corrosive Flux

A flux that contains corrosive chemicals such as halides, amines, inorganic or organic acids that can cause oxidation of copper or tin conductors.

C-Stage

The condition of a resin polymer when it is in a solid state with high molecular weight. Being insoluble and infusion.

CTE (Coefficient of Thermal Expansion)

The measure of the amount a material changes in any axis per degree of temperature change.

Curing

The irreversible process of polymerizing a thermosetting epoxy in a temperature-time profile.

Curing Time

The time needed to complete curing of an epoxy at a certain temperature.

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D

Deburring

Process of removing burrs after PCB drilling.

Defect

Any nonconformance to specified requirements by a unit or product.

Definition

The fidelity of reproduction of pattern edges, especially in a printed circuit relative to the original master pattern.

Delamination

A separation between any of the layers of the base of laminate or between the laminate and the metal cladding originating from or extending to the edges of a hole or edge of board.

Design Rule

Guidelines that determine automatic conductor routing behavior with respect to specified design parameters.

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Design Rule Checking

The use of a computer program to perform continuity verification of all conductor routing in accordance with appropriate design rules.

Desmear

The removal of friction-melted resin and drilling debris from a hole wall.

Dewetting

A condition that results when molten solder has coated a surface and then receded, leaving irregularly shaped mounds separated by areas covered with a thin solder film and with the base material not exposed.

DFSM

Dry Film Solder Mask.

Die Bonder

The placement machine bonding IC chips onto a chip-on-board substrate.

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Die Bonding

The attachment of an IC chip to a substrate.

Die

Integrated circuit chip as diced or cut from a finished wafer.

Dielectric

An insulating medium which occupies the region between two conductors.

Digitizing

The converting of feature locations on a flat plane to a digital representation in X-Y coordinates.

Dimensional Stability

A measure of the dimensional change of a material that is caused by factors such as temperature changes, humidity changes, chemical treatment, and stress exposure.

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DIP

Dual in-line package with two rows of leads from the base in standard spacing between the leads and row. DIP is a through-hole mounting package.

Double-Sided Assembly

PCB assembly with components on both sides of the substrate.

Double-Sided Board

A printed board with a conductive pattern on both sides.

DRC

Design rule check.

Dry-Film Resists

Coating material specifically designed for use in the manufacture of printed circuit boards and chemically machined parts. They are suitable for all photomechanical operations and are resistant to various electroplating and etching processes.

Dry-Film Solder Mask

Coating material (dry-film resist) applied to the printed circuit board via a lamination process to protect the board from solder or plating.

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E

Edge Clearance

The smallest distance from any conductors or components to the edge of the PCB.

Edge Connector

A connector on the circuit-board edge in the form of gold plated pads or lines of coated holes used to connect other circuit board or electronic device.

Electroless Copper

A thin layer of copper deposited on the plastic or metallic surface of a PCB from an autocatalytic plating solution (without the application of electrical current).

Electroless Deposition

The chemical coating of a conductive material onto a base material surface by reduction of metal ions in a chemical solution without using electrodes compared to electroplating.

Electroplating

The electro deposition of an adherent metal coating on a conductive object. The object to be plated is placed in an electrolyte and connected to one terminal of a D.C. voltage source. The metal to be deposited is similarly immersed and connected to the other terminal.

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Epoxy

A family of thermosetting resins used in the packaging of semiconductor devices. Epoxies form a chemical bond to many metal surfaces.

Epoxy Smear

Epoxy resin which has been deposited on edges of copper in holes during drilling either as uniform coating or in scattered patches. It is undesirable because it can electrically isolate the conductive layers from the plated-through-hole interconnections.

ESR

Electro-statically applied Solder Resist.

Etchback

The controlled removal of all components of the base material by a chemical process acting on the sidewalls of plated-through holes to expose additional internal conductor areas.

Etching

The chemical, or chemical and electrolytic, removal of unwanted portions of conductive materials.

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F

Fine Pitch

Fine pitch is more commonly referred to surface-mount components with a lead pitch of 25 mils or less.

Finger

A gold-plated terminal of a card-edge connector. Also see Gold Finger.

First Article

A sample part or assembly manufactured prior to the start of production for the purpose of assuring that the manufacturer is capable of producing a product that will meet specified requirements.

Flux

The material used to remove oxides from metal surfaces and enable wetting of the metal with solder.

FR4

Flame Retardant laminate made from woven glass fiber material impregnated with epoxy resin.

Functional Test

The electrical testing of an assembled electronic device with simulated function generated by the test hardware and software.

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G

Gerber File

Data file used to control a photo plotter.

GI

The woven glass fiber laminate impregnated with polyimide resin.

Gold Finger

The gold-plated terminal of a card-edge connector. Also see Finger.

Ground Plane

A conductor layer, or portion of a conductor layer, used as a common reference point for circuit returns, shielding or heat sinking.

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H

HDI (High Density Interconnect)

Ultra-fine-geometry multi-layer PCB constructed with conductive surface Microvia connections between layers. These boards also usually include buried and/or blind vias are made by sequential lamination.

HDI

High Density Interconnect.

Hermetic

Airtight sealing of an object.

Hole Breakout

A condition in which a hole is partially surrounded by the land.

Hole Density

The number of holes per unit area on a PCB.

Hole Pattern

The arrangement of all holes in a printed board with respect to a reference point.

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I

In-Circuit Test

Electrical test of individual component or part of the circuit in a PCB assembly instead of testing the whole circuit.

Insulation Resistance

The electrical resistance of an insulating material that is determined under specific conditions between any pair of contacts, conductors, or grounding devices in various combinations.

Interconnect Stress Test

The IST system is designed to quantify the ability of the total interconnect to withstand the thermal and mechanical strains, from the as manufactured state, until the products reaches the point of interconnect failure.

Interstitial Via Hole

An embedded through-hole with connection of two or more conductor layers in a multilayer PCB.

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J

Jump-Scoring

similar to v-scoring, this is a process that is used when a printed circuit board is panelized. It allows for a score line to jump over most of the panel border, leaving the border largely intact, and as a result, stronger and more rigid, resulting in a stiffer and stronger assembly panel.

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K

KGB

Known good board or assembly. Also known as a golden board.

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L

Laminate

The plastic material usually reinforced by glass or paper that supports the copper cladding from which circuit traces are created.

Laminate Thickness

Thickness of the metal-clad base material, single or double sided, prior to any subsequent processing.

Laminate Void

An absence of epoxy resin in any cross-sectional area which should normally contain epoxy resin.

Lamination

The process manufacturing a laminate using pressure and heat.

Land

The portion of the conductive pattern on printed circuits designated for the mounting or attachment of components. Also called Pad.

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Leakage Current

A small amount of current that flows across a dielectric area between two adjacent conductors.

Legend

A format of lettering or symbols on the printed circuit board; e.g., part number, serial number, component locations and patterns.

Line

A thin conductive area on a PCB surface or internal layer usually composed of lands (to which component leads are connected) and paths (traces). Also known as a “conductor”.

LPI

Liquid Photo-Imageable solder mask that uses photographic imaging to control a thinner mask deposition than the dry film solder mask.

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M

Major Defect

A defect that is likely to result in failure of a unit or product by materially reducing its usability for its intended purpose.

Mask

A material applied to enable selective etching, plating, or the application of solder to a PCB.

Measling

Discrete white spots or crosses below the surface of the base laminate that reflect a separation of fibers in the glass cloth at the weave intersection.

Microsectioning

The preparation of a specimen of a material, or materials, that is to be used in metallographic examination. This usually consists of cutting out a cross-section followed by encapsulation, polishing, etching, and staining.

Microvia

Usually defined as a conductive hole with a diameter of 0.006 in or less that connects layers of a multilayer PCB. Often used to refer to any small geometry connecting hole the creation of which is beyond the tradition practical drilling capabilities.

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Minimum Conductor Space

The smallest distance between any two adjacent conductors, such as traces, in a PCB.

Minimum Conductor Width

The smallest width of any conductors, such as traces, on a PCB.

Minor Defect

A defect that is not likely to result in the failure of a unit or product or that does not reduce its usability for its intended purpose.

Multilayer Printed Boards

Printed boards consisting of a number of separate conducting circuit planes separated by insulating materials and bonded together into relatively thin homogeneous constructions with internal and external connections to each level of the circuitry as needed.

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N

NC Drill

Numeric Control drill machine used to drill holes at exact locations of a PCB specified in NC Drill File.

Netlist

List of parts and their connection points which are connected in each net of a circuit.

Node

A pin or lead to which at least two components are connected through conductors.

NPTH

Non-plated trough-hole.

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P

Pad

The portion of the conductive pattern on printed circuits designated for the mounting or attachment of components. Also called land.

Panel

A rectangular sheet of base material or metal-clad material of predetermined size that is used for the processing of printed boards and, when required, one or more test coupons.

Pattern

The configuration of conductive and nonconductive materials on a panel or printed board. Also, the circuit configuration on related tools, drawings and masters.

Pattern Plating

The selective plating of a conductive pattern.

PCB

Printed Circuit Board. Also called Printed Wiring Board (PWB).

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PCMCIA

Personal Computer Memory Card International Association.

PEC

Printed Electronic Component.

Photo Print

The process of forming a circuit pattern image by hardening a photosensitive polymeric material by passing light through a photographic film.

Photographic Image

An image in a photo mask or in an emulsion that is on a film or plate.

Photoplotting

A photographic process whereby an image is generated by a controlled light beam that directly exposes a light-sensitive material.

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Pick-and-Place

A manufacturing operation of assembly process in which components are selected and placed onto specific locations according to the assembly file of the circuit.

Pitch

The center-to-center spacing between conductors, such as pads and pins, on a PCB.

Plastic Leaded Chip Carrier (PLCC)

A component package with J-leads.

Plated Through Hole

A hole with plating on its walls that makes an electrical connection between conductive layers, external layers, or both, of a printed board.

Plating Resist

Material deposited as a covering film on an area to prevent plating on this area.

Plating Void

The area of absence of specific metal from a specific cross-sectional area.

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Plotting

The mechanical converting of X-Y positional information into a visual pattern such as artwork.

PrePreg

Sheet material (e.g., glass fabric) impregnated with a resin cured to an intermediate stage (B-stage resin).

Printed Board

The general term for completely processed printed circuit or printed wiring configurations. It includes single, double-sided, and multilayer boards, both rigid and flexible.

Printed Circuit

A conductive pattern that comprises printed components, [learn_more caption="printed wiring, or a combination thereof, all formed in a predetermined design and intended to be attached to a common base. (In addition, this is a generic term used to describe a printed board produced by any of a number of techniques).

Printed Wiring Board

A part manufactured from rigid base material upon which completely processed printed wiring has been formed.

PTH (plated-through Hole)

A plated hole used as a conducting interconnection between different layers or sides of a PCB either used as connection for through-hole component or as a via.

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R

Reflow Soldering

Melting, joining and solidification of two coated metal layers by application of heat to the surface and predeposited solder paste.

Reflowing

The melting of an electrodeposited tin/lead followed by solidification. The surface has the appearance and physical characteristics of being hot-dipped.

Registration

The degree of conformity to the position of a pattern, or a portion thereof, a hole, or other feature to its intended position on a product.

Resin (Epoxy) Smear

Resin transferred from the base material onto the surface of the conductive pattern in the wall of a drilled hole.

Resist

Coating material used to mask or to protect selected areas of a pattern from the action of an etchant, solder or plating.

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RF (radio frequency) and Wireless Design

A circuit design that operates in a range of electromagnetic frequencies above the audio range and below visible light. All broadcast transmission, from AM radio to satellites, falls into this range, which is between 30KHz and 300GHz.

Rigid-Flex

A PCB construction combining flexible circuits and rigid multi layers usually to provide a built-in connection or to make a three dimensional form that includes components.

Route (or Track)

A layout or wiring of an electrical connection.

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S

Screen Printing

A process for transferring an image to a surface by forcing suitable media through a stencil screen with a squeegee.

Silk Screen (Silk Legend)

Epoxy-ink Legend printed on PCB. The most common colors used are white and yellow.

Single-Sided Board

A printed board with conductive pattern on one side only.

Small Outline Integrated Circuit (SOIC)

An integrated circuit with two parallel rows of pins in surface mount package.

SMD

Surface Mount Device.

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SMOBC

Solder mask Over Bare Copper

SMT

Surface Mount Technology. Defines the entire body of processes and components which create printed circuit board assemblies with lead less components.

Solder

An alloy that melts at relatively low temperatures and is used to join or seal metals with higher melting points. A metal alloy with a melting temperature below 427°C (800°F).

Solder Bridging

Solder connecting, in most cases, misconnecting, two or more adjacent pads that come into contact to form a conductive path.

Solder Bumps

Round solder balls bonded to the pads of components used in face-down bonding techniques.

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Solder Mask

Non-preferred term for solder resist.

Solder Mask or Solder Resist

Coating to prevent solder to deposit on.

Solder Wick

A band of wire removes molten solder away from a solder joining or a solder bridge or just for desoldering.

SPC

Statistical Process Control. The collection of process data and creation of control charting is a tool used to monitor processes and to assure that they remain In Control or stable. Control charts help distinguish process variation due to assignable causes from those due to unassignable causes.

Step-And-Repeat

A method by which successive exposures of a single image are made to produce a multiple image production master.

Substrate

A material on whose surface adhesive substance is spread for bonding or coating. Also, any material which provides a supporting surface for other materials used to support printed circuit patterns.

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T

Temperature Coefficient (TC)

The ratio of a quantity change of an electrical parameter, such as resistance or capacitance, of an electronic component to the original value when temperature changes, expressed in %/ºC or ppm/ºC.

Test Coupon

A portion of a printed board or of a panel containing printed coupons used to determine the acceptability of such a board.

Test Point

A specific point in a circuit board used for specific testing for functional adjustment or quality test in the circuit-based device.

Testing

A method for determining whether sub-assemblies, assemblies and/or a finished product conform to a set of parameter and functional specifications. Test types include: in-circuit, functional, system-level, reliability, environmental.

Thief

An extra cathode placed as to divert to itself some of the current from portions of the board which otherwise would receive too high a current density.

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Tooling Holes

The general term for holes placed on a PCB or a panel of PCBs for registration and hold-down purposes during the manufacturing process.

Turnkey

A type of outsourcing method that turns over to the subcontractor all aspects of manufacturing including material acquisition, assembly and testing. Its opposite is consignment, where the outsourcing company provides all materials required for the products and the subcontractor provides only assembly equipment and labor.

Twist

A laminate defect in which deviation from planarity results in a twisted arc.

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U

UL

Underwriter’s Laboratories. A popular safety standard for electrical devices supported by many underwriters.

Underwriters Symbol

A logotype denoting that a product has been recognized (accepted) by Underwriters Laboratories Inc. (UL).

UV Curing

Polymerizing, hardening, or cross linking a low molecular weight resinous material in a wet coating ink using ultra violet light as an energy source.

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V

Via

A plated through hole that is used as an inter-layer connection, but doesn’t have component lead or other reinforcing material inserted in it.

Void

The absence of any substances in a localized area.

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W

Wave Soldering

A process wherein assembled printed boards are brought in contact with a continuously flowing and circulating mass of solder.

Wicking

Migration of copper salts into the glass fibers of the insulating material.

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