PCB Glossary

Terms and glossary in PCB & PCBA industry.


Acceptance Test – The tests that determine the acceptability of boards as agreed to by purchaser/vendor.

Accepted Quality Level (AQL) – The maximum number of defects per 100 units that can be considered satisfactory as a process average.

Access Holes – A series of holes in successive layers. Each set has a common centre or axis. The holes of a multi-layer printed board provide access to the surface of the land in one of the layers of the board.

Accuracy – The deviation of the measured or observed value from the accepted reference.

Acrylic Resin – A thermosetting, transparent resin.

Activated Rosin Flux – A mixture of rosin and small amounts of organic-halide or organic-acid activator, which improves the ability of a flux to remove surface oxides from the surfaces being joined.

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 an 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.

Adhesion Layers – The metal layer that adheres a barrier metal to a metal land on the surface of an integrated circuit.

Adhesive – A substance such as glue or cement used to fasten objects together. In surface mounting, an epoxy adhesive is used to adhere SMDs to the substrate.

Aging – The change of a property, e.g. solderability, with time.

Air Gap – The non-conductive air space between current carrying conductors such as traces, pads, ground planes, etc.

Algorithm – A procedure for solving a problem, usually mathematical.

Alkyd – A thermosetting resin with good electrical properties used for moulding the bodies of components.

Ambient – The surrounding environment coming into contact with the system or PCB in question.

Analog Circuit – A circuit comprised primarily of individual (discrete) components, such as resistors, capacitors, diodes, transistors, etc. The circuit output is a continuous electrical signal that varies in frequency, amplitude, etc., as a function of the input. The magnitude is represented by physical variables such as voltages, current, resistance, rotation, etc.

Analog Circuit Simulator – A tool used to verify the design (or portions thereof) in the analog domain by applying virtual test signals to a virtual model of the design.

Analog Functional Test – At the board level, various analog test signals are applied to a PCB through a switch to point out current outputs.

Analog In-circuit Test – A system measuring component values on a populated PCB before power is applied.

Anchoring Spur – An extension of a land(like one or two blind paths)on a flexible printed board that extends beneath the cover lay to assist in holding the land to the base material.

Angle of Attack – The angle between the face of the squeegee and the surface of the screen.

Annotation – Text or legend pertinent to a board design; text appears off the board areas and consists of lettering and symbols while legend appears on the boards.

Annular Ring – that portion of conductive material completely surrounding a hole.

ANSI – Acronym for “American National Standards Institute”, an organization formed by industry and the US Government to develop trade and communication standards.

AOI – Automatic Optical Inspection.

Aperture List – List containing the shapes and dimensions of pads and tracks, etc., to expose on the film in a photoplotter.

AQL – Acceptable Quality Level. The maximum number of defectives likely to exist within a population lot that can be considered to be contractually tolerable.

Aqueous Cleaning – A water-based method that may include neutralizers, saponifiers, surfactants, dispersants and anti-foaming agents.

Arc Resistance – The resistance of a material to the effects of a high voltage, low-current, under prescribed conditions, passing across the surface of the material. The resistance is stated as a measure of the total elapsed time required to form a conductive path of the surface (material carbonized by the arc).

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

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.

ASCII – Acronym for “American Standard Code for Information Interchange”; a seven-bit code that assigns numeric values to letters of the alphabet, the ten decimal digits, punctuation marks and other characters.

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 Drawing – i: A drawing depicting the locations of components, with their reference designators (q.v.), on a printed circuit. ii:The document that shows a printed board, components and any information necessary to describe joining them together in order to perform a specific function.

Assembly File – A drawing describing the locations of components on a PCB.

Assembly House – A manufacturing facility for attaching and soldering components to a printed circuit.

Assembly Language – A computer language of brief expressions for translation into a machine language.

ATE – Automatic Test Equipment

Automated Component Insertion – Assembling discrete components to PCBs via electrically controlled equipment.

Automated Test Equipment (ATE) – Equipment that automatically tests and analyzes functional parameters to evaluate performance of the tested electronic devices.

Automatic Test Equipment – Hardware that automatically analyses functional or static parameters to evaluate performance degradation. It also performs fault isolation.

AWG – American Wire Gauge. A method of specifying wire diameter; the higher the number, the smaller the diameter.

Axial Lead – A lead extending out the end and along the axis of a resistor, capacitor or other axial part rather than from the bottom.

Azeotrope – Two or more polar and non-polar solvents that behave when mixed as a single solvent to remove polar and non-polar contaminants with a boiling point lower than its components.


B&B – Blind and Buried via holes.

Backdriving – An in-circuit test procedure for digital circuitry.

Backpanel (Backplane) – Mother Board. Also called back plane, or matrix board. A relatively large printed circuit board on which modules, connectors, sub-assemblies or other printed circuit boards are mounted and inter connections made by means of traces on the board.

Bare Board – A PCB having all lines, pads and layers intact but without components installed. An unassembled PCB.

Barrel – The cylinder formed by plating through a drilled hole.

Base Copper – The original, thin copper foil present on one or both sides of a copper clad laminate. During PCB manufacture, part of this base copper will be removed by etching. Conductors on the simplest PCBs consist of base copper only.

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.

Base Laminate – The substrate material upon which the conductive wiring pattern may be formed.

Base Material – The insulating material (either rigid or flexible ) as well as the copper foils bonded on one or both sides. It is a synonym for copper-clad laminate, i.e., the basic raw material for PCB manufacture. This also supports all components after assembly.

Base Material Thickness – The thickness of the base material, excluding metal foil or material deposited on the surface.

Base Solderability – The ease with which a metal or metal alloy surface can be wetted by molten solder under minimum realistic conditions.

Basic Wettability – The ease with which a metal or metal alloy can be wetted by molten solder.

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).

Bed-of-Nails – A method of PCB testing involving a fixture containing a field of spring-loaded pins that are co-ordinated with strategic points or nodes on the board to which they are brought into contact.

Bellows Contact – A connector contact which is a flat sprint folded to provide a uniform spring rate over the full tolerance range of the mating unit.

BGA – Ball Grid Array. Leadless array packaging technology in which solder balls are mounted to the underside of the package.

Biscuit Frame – An array of circuits on a larger “mother” panel.

Bleeding – A condition in which liquid solder resist or rotation spreads larger than the defined apperture.

Blind Via – A via that reaches only one layer beneath the outer layer on one side of a muti-layer board.

Blister – De-lamination in the form of a localized swelling and separation between any of the Layers of a lamination base material, or between base material and conductive foil or protective coating.

Blistering – A localized swelling and separation between any of the layers of a laminated base material, or between base material and conductive foil. It is a form of de-lamination. Also separation of solder mask layer and conductive pattern.

Blow Hole – A void in the solder fillet caused by outgassing from the barrel of a plated through hole.(see also outgassing)

Bluetooth – Bluetooth is a short-range (up to 10m) 2.4GHz wireless connectivity standard intended for such applications as wireless personal area networks (PANs). These PANs can be used to exchange data between devices such as cellphones, digital cameras, printers and household appliances at data rates of up to 721 Kbps (kilo bits per second).

Blutter Coat – An external layer of resin over the reinforcing structure of base material.

Board Density – A measure of the ratio of the area of the board used by parts to the total available area of the board. A board with less than 50 to 60 per cent of the available area should be able to be done single-sided, more than 75 to 80 per cent may have to go to multi-layer.

Board Thickness – The overall thickness of the base material and all conductive materials deposited thereon.

Body – The portion of an electronic component exclusive of its pins or leads.

BOM (Bill of materials) – 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.

Bond Interface – The common area between a lead and a land to which it has been terminated.

Bond Lift-off – A failure condition in which a lead is separated from its bonding surface.

Bond Strength – The force perpendicular to a board’s surface required to separate two adjacent layers of the board, expressed as force pre unit area.

Bonding Layer – An adhesive layer used in bonding together other discrete layers of multi-layer printed board during lamination.

Bonding Time – The duration from hot-bar-heat-up (contact with lead and pad ) until the solder joint is completed.

Border Data – Patterns that appear in the border area, such as tooling features, test patterns and registration marks.

Boundary Scan – A self-test designed into components at the silicon level, permitting testing via a built-in, four-or-five-pin test bus accessing I/O pins

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

Branched Conductor – A conductor which connects electrically two or more leads on a printed board assembly. Some branched conductors, notably ground, support and re-set signal, connect many leads.

Brazing Alloy – A metal alloy (solder) which melts above 450℃ but below metals being joined.

Breakdown Voltage – The voltage at which an insulator or dielectric ruptures or at which ionization and conduction take place in a gas or vapour.

Bridged Joint – Solder that spans across two or more conductors causing an electrical short-circuit.

Bridging – A condition where excess solder builds up in the air gap between conductors and causes them to short together. Solder bridging generally occurs during the wave soldering process. Bridging is basically short-circuiting of a pad to an adjacent track or pad on a board.

B-stage – (prepreg) Partially cured resin (mostly reinforced with glass cloth) which will soften under a special range of temperature and which can be used to bond together cured laminate sheets to form a multi-layer board.

B-Stage Material – Laminate impregnated with a resin and cured to an intermediate stage (B-stage resin). Normally designated as prepreg.

B-Stage Resin – A resin in an intermediate state of cure. The cure is normally completed during the laminating cycle.

Built-In Self Test – An electrical testing method that allows the tested devices to test itself with specific added-on hardware.

Bulge – A swelling of a printed board that is usually caused by internal de-lamination or separation of fibres.

Buried Via – A via that does not reach a surface layer on either side of a multi-layer board. The via transcends only inner layers of the board.

Burn-in – A method of testing devices via electrical stress vs temperature and/or time so that units prone to failure are eliminated.

Burr – A ridge left on the outside copper surface after drilling.

Bus – A heavy trace or conductive metal strip on the printed circuit board used to distribute voltage, grounds, etc., to smaller branch trances.

Bus Bar – A conduit, such as a conductor on a printed board, for distributing electrical energy.

Bypass Capacitor – A capacitor which provides a comparatively low impedance ac (alternating current ) around a circuit element.


CAD – Computer Aided Design.

CAD system – Computer-aided design that permits the interactive use of computers, programs and procedures in the design process. Decisions are made by the operator while the computer provides the data manipulation functions.

CAD/CAM system – Computer-aided design is the use of special software tools to formulate printed circuit patterns. Computer-aided manufacturing translates such designs into actual products.

CAM – Computer Aided Manufacturing.

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

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

Capacitive Coupling – The electrical interaction between two conductors caused by the capacitance between them.

Capillary Action – A phenomenon of force adhesion and cohesion that prompts liquids ( molten solder) to flow against gravity between closely spaced solid surface, such as component leads and pads.

CARD – Printed Board. The general term for completely processed printed circuit or printed wiring configuration. It includes signle, double, and multi-layer boards, both rigid and flexible.

Cast Adhesive – Special sheet adhesive material used for bonding polyimide multi-layer boards and flexi-rigids ( similar to prepreg = B-Stages ).

Catalyst – A chemical that speeds or changes the cure of a resin but does not become a part of the final product. Examples: hardeners, promoters, inhibitors.

CBGA – Ceramic Ball Grid Array. A ball grid array package with a ceramic substrate.

Chamfer – A corner which has been rounded or shaped to eliminate an otherwise sharp edge.

Characteristic Impedance – The ratio of voltage to current in a propagating wave, i.e., the impedance which is offered to this wave at any point of the line. The characteristic impedance is expressed in ohms.

Check Plots – Pen plots that are suitable for checking only. Pads are represented as circles and thick traces as rectangular outlines instead of filled-in artwork. This technique is used to enhance the transparency of multiple layers.

Chemical Conversion Coating – A protective coating produced by the chemical reaction of a metal with a chemical solution.

Chemical Hole Clearing – The chemical process for cleaning conductive surfaces exposed within a hole.

Chemically-deposited Printed Chip on board – In this technology integrated circuits are glued and wire-bonded directly to printed circuit boards instead of first being packaged.

Chip – The individual circuit or component of a silicon wafer, the leadless form of an electronic component.

Chip on board – Component packaging technology in which bare integrated circuits are attached directly to the surface of a substrate and interconnected to the substrate most often by means of microscopic wires.

Chip Testers – Large computer-based systems that test individual ICs, especially LSI and VLSI.

Circuit Tester – Generic term for volume tester of PCBs, such as bed-of-nails, footprint, guided probe, internal trace, loaded board, bare board and parts testing.

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

Circumferential Separation – A crack in the plating extending around the entire circumference of a plated through-hole.

Clad – A condition of the base material to which a relatively thin layer or sheet of metal foil has been bonded at one or both of its sides, e.g. a metal clad base material.

Clad Or Cladding – A relatively thin layer or sheet of metal foil which is bonded to a laminate core to form the base material for printed circuits.

Clamshell Fixture – An in-circuit test fixture to probe both sides of a PCB.

Class Transition Temperature – TG-value, temperature at which resin ceases to act as a solid, Till this temperature, no separation will take place between resin/copper/reinforcement.

Clearance – Metal to metal gaps on a board.

Clearance Hole – A hole in the conductive pattern larger than, but concentric with, a hole in the printed board base material.

Clinched-wire through Connection – A connection made by a wire which is passed through a hole in a printed circuit board, and subsequently formed, or clinched, in contact with the conductive pattern on each side of the board, and soldered.

Coating – A thin layer of material, either conductive or insulating, applied over components or base materials.

COB – Chip-on-Board. A configuration in which a chip is directly attached to a printed circuit board or substrate by solder or conductive adhesives.

Coefficient of Thermal Expansion – The fractional change in dimension of a material for a unit change in temperature expressed in ppm/C.

Cold Solder Connection – A solder connection that exhibits poor wetting and that is characterized by a greyish porous appearance.

Compatibility – In which materials can be mixed or brought into contact with no reaction or separation.

Compiler – A software module that analyses and converts programs from a high-level language to binary machine codes.

Component – Any of the basic parts used in building electronic equipment, such as a resistor, capacitor, DIP or connector, etc.

Component Density – The quantity of components on a unit area of printed board.

Component Hole – A hole in a PCB through-which a component lead passes in order to be soldered or connected mechanically to the printed circuit and electrically to the conductive pattern. Synonym: mounting hole. The hole is used for the attachment and electrical connection of component terminations, including pins and wires, to the printed board.

Component Side – (Primary side) The surface layer of a board on which most of the components are placed. Component side is also referred to as the top side (layer one-counting downwards) of the board.

Conductive Adhesive – A material to which metal particles (usually silver ) are added to increase electrical conductivity.

Conductive Foil – A thin sheet of metal that may cover one or both sides of the base material and is intended to form the conductive pattern.

Conductive Pattern – The configuration or design of the conductive material on the base laminate. Includes conductors, lands, and through connections.

Conductor – A single conductive path in conductive pattern. A PCB has at least one layer of conductors. Synonyms: path, trace.

Conductor Base width – The conductor width at the plane of the surface of the base material. See also: Conductor width.

Conductor Layer – The total conductive pattern formed upon one side of a single layer of base material.

Conductor Pattern – The configuration or design of the conductive material on the base laminate. Includes conductors, lands, and through connections.

Conductor Side – The side of a single-sided printed board containing the conductive pattern.

Conductor Spacing – The average or minimum (as specified) distance between the adjacent edges of conductors on the same layer of a printed board.

Conductor Thickness – The thickness of the conductor at any point chosen at random on the printed board, normally viewed from vertically above unless otherwise specified.

Conductor Width – The observable width of the pertinent conductor at any point chosen at random on the printed board, normally viewed from vertically above unless otherwise specified.

Conductor-to-hole Spacing – The distance between the edge of a conductor and the edge of a supported or unsupported hole.

Conformal Coating – A thin dielectric cover brushed, dipped or sprayed over parts and circuits of PCBs for environmental and mechanical protection.

Connection – One plug or receptacle which can be easily joined to or separated from its mate. Multiple-contact connectors join two or more conductors with others in one mechanical assembly.

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

Connector Tongue – A protrusion of the Printed Circuit Board edge that is manufactured to a configuration to mate with a receptacle that provides electrical and/or mechanical junction between the Printed Circuit Board and other Circuitry.

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.

Contact Area – The common area between a conductor and a connector through which the flow of electricity takes place.

Contact Resistance – The electrical resistance of the metallic surfaces at their interface in the contact area under specified conditions.

Contact Spacing – The distance between the centre lines of adjacent contact areas.

Contaminate / Contaminant – An impurity or foreign substance whose presence on printed wiring assemblies could electrolytically, chemically, or galvanically corrode the system.

Continuity Testing – A procedure in which voltage is applied to two interconnected lands to ascertain the presence or absence of current flow.

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.

Copper Clad – A material, usually supplied in large sheets, consisting of a base material to one or both sides of which a thin copper foil is boned. Synonym: laminate.

Copper Foil – See Foil – Quality electrolytic copper used to form conductive patterns on printed circuits. It is available in a number of weights (thickness) the traditional weights are 0.5, 1 and 2 ounces per square foot. (18, 35 and 70μm thick).

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.

Copper-mirror Test – A corrosivity test for fluxes in which the compound’s reaction to a copper film vacuum-deposited on a glass plate is noted.

Corner Mark – Marks placed inside the edges of PCB corners to align and register the 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.

Corrosive Fluxes – Materials of inorganic acids and salts for surfaces of difficult solderability. Also called acid fluxes.

Cosmetic Defects – A smear or stain on the board representing flux residue after soldering and a variation from conventional appearance.

Coupon – Test Coupon. One of the patterns of the quality conformance test circuitry area.

Cover Lay, Cover Layer, Cover Coat – An outer layer(s) of insulating material applied over the conductive pattern on the surface of the printed board.

Cracking – A condition that makes breaks or separations in coatings that extends through to an underlying surface.

Crazing – A condition existing in the base material in the form of connected white spots or “crosses” on or below the surface of the base material, reflecting the separation of fibres in the glass cloth and connecting weave intersections.

Crimp Contact – A type of connector contact whose end is a hollow cylinder that can be crimped onto a wire inserted within it.

Cross-hatching – The breaking of large conductive areas by use of a pattern of voids in the conductive material.

Cross-linking – The formation of chemical ties between reactive atoms in the molecular chain of a plastic.

Cross-talk – The undesirable interference caused by the coupling of energy between single paths.

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

C-stage Material Laminate – The condition of a resin polymer when it is in the solid-state, with high molecular weight, being insoluble and infusible.

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

Cure – Change of physical properties of a material via chemical reaction or heat and catalysts, usually from a liquid to a solid.

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.

Current-carrying Capacity – The maximum current which can be carried continuously, under specified conditions, by a conductor without causing degradation of electrical or mechanical properties of the printed circuit board.

Cut – Open circuit. An unwanted break in the continuity of an electrical circuit, that prevents current from flowing.

Cycle Rate – A component placement term measuring machine speed from pick-up to board location and return.


Database – A collection of inter-related data items stored together without redundancy to serve one or more applications.

Datum – A defined point, line, or plane used to locate the pattern of layer for manufacturing or inspection, or for both purposes.

De-bugging – The process of locating and fixing problems (bugs) in the hardware and software portions of an electronic system.

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 a base material or between the laminate and the conductive foil, or both.

Dendrite – Metallic filaments growing between pads and traces resulting from electromigration.

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

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

Design Width of Conductor – The width of a conductor as delineated or noted on the master drawing. (See also: Conductor Base Width and Conductor Width).

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

Device – An individual electrical element, usually in an independent body, which cannot be further reduced without destroying its stated function.

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.

De-wetting – A solder coating that has receded, leaving irregular deposits and indicating that the base metal has not been adequately de-oxidized.

Dezincification – Kind of galvanic corrosion, generally associated with two-phase brass alloys, in which the zinc-rich beta phase is selectively leached out of the brass. It occurs when brazed joints are exposed to salt or seawater.

DFSM – Dry Film Solder Mask.

Dice – Two or more dies.

Die – The uncased and normally leadless form of an electronic component that is either active or passive, discrete or integrated.

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

Die Bonding – The attachment of an IC chip to a substrate.

Dielectric – An insulating medium which occupies the region between the conductors. It is also the distance between bonded inner layer conductors.

Dielectric Constant – The property of a dielectric which determines the electrostatic energy stored per unite volume for a potential gradient.

Dielectric Strength – The maximum voltage that a dielectric material can withstand, under specified conditions, without rupturing (usually expressed as volts/units thickness).

Digital Circuit – A circuit comprised mostly of integrated circuits and operate, like a switch (i.e., it is either “ON” or “OFF”).

Digital Logic Simulator – A tool used to verity the design (or portions thereof) in the digital domain by applying virtual test signals to a virtual model of the design.

Digitizing – Any method of reducing feature locations on a flat plane to digital representation of X-Y co-ordinates.

Dimensional Hole – A hole in a printed board where the means of determining location is by co-ordinate values not necessarily coinciding with the stated grid.

Dimensional Stability – A measure of dimensional change cause by such factory as temperature, humidity, chemical treatment, age, or stress (usually expressed as units/unit).

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.

DIP Soldering – A process whereby printed boards are brought into contact with the surface of a static pool of molten solder for the purpose of soldering the entire exposed conductive pattern in one operation.

Discrete Component – A component which has been fabricated prior to its installation (i.e., resistors, capacitors, diodes, transistors, capacitors, diodes, transistors, etc). A single function component.

Dispersent – A chemical added to the cleaning solution to improve its particulate-removal ability.

Disturbed Solder Connection – A solder connection that is characterized by the appearance that there was motion between the metals being joined when the solder was solidifying (not accepted).

Documentation – Information on an assembly that explains the basic design concept, type and quantity of parts and materials, special manufacturing instruction, and up-to-date revisions.

Double-Sided Assembly – A PCB with components mounted on both skies.

Double-Sided Board – A printed board with a conductive pattern on both sides.

DPF – Disc Plot Format.

Drag Soldering – The making of soldered terminations by dipping the colder side of a supported printed board with through-hole mounted components into the surface of a static pool of molten solder and moving it horizontal in one direction.

Drag-out – A measure of cleaning solution lost via board emergence after immersion.

DRC – Design Rule Check: Checks the integrity of print (PCB) so that problems like short-circuits, unrouted nets, etc. are recognized.

Drills – Solid, carbide cutting tools designed specifically for the fast removal of material in extremely abrasive, glass-epoxy materials.

Dross – Oxide and other contaminates which form on the surface of molten solder.

Dry Film Resists – Coating material in the form of laminated photo-sensitive foils specifically designed for use in the manufacture of printed circuit boards and chemically machined parts. They are resistant to various electroplating and etching processes.

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.

Drying Time – Within the re-flow process after pre-heat and before peak re-flow temperature wherein volatile materials escape from the solder paste.

Dual Solder Wave – In wave soldering, the first wave’s multi-directional jet leaves solder on all contacted surfaces, followed by the second (flat) wave, which effects a finishing appearance by removing bridges and icicles. Intended for surface mount soldering.

Dummy Component – A mechanical package without the die, used to verify placement processes.

Durometer – A measurement of the hardness of a non-metal such as rubber, plastic, etc. Also the instrument for such measurement.


Edge Clearance – The distance of a pattern, components, or both, from the edges of the printed circuit board.

Edge Connector – A connector (can be gold-plated edge contacts or a series of parallel lines of holes).

Edge Spacing – The distance of a pattern, components, or both, from the edges of the printed board and intended for mating with an edge-board connector.

Edge-board Contacts – A series of contacts printed on or near any edge of a printed board and intended for mating with an edge-board connector.

Electroless Copper – A layer of copper plated on to an insulating or conductive surface of a PCB by chemical reduction, that is, without the use of applied electrical current.

Electroless Deposition – The deposition of conductive material from an auto-catalytic plating solution without application of electrical current.

Electron-beam Bonding – Terminations made by heating with a stream of electrons in a vacuum.

Electroplating – The electrodeposition of a metal coating on a conductive object. The object to be plated is placed in an electrolyte and connected to the relative terminal of a dc voltage source. The metal to be deposited is similarly immersed and connected to the positive terminal. Ions of the metal provide transfer to metal as they make up the current flow between the electrodes.

Embedded Component – A discrete component that is fabricated as an integral part of a printed board.

Emulsion Side – The side of the film on which the photographic image is defined.

Entrapment – The damaging admission and trapping of air, flux and fumes; it is caused by contamination and plating.

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

Epoxy Resins – Materials that form straight chain thermoplastic and thermosetting resins having good mechanical properties and dimensional stability.

Epoxy Smear – Epoxy resins which has been deposited onto the surface or edges of the conductive pattern during drilling. Also called resin smear.

ERBGF – Epoxy Resin Bonded Glass Fibre (See FR4).

ERC – Electrical Rule Check: checks the integrity of a circuit (SCH) so that problems like open inputs, shorted outputs and much more are recognized.

Escape Rate – The percentage of defects not defected vs. the total inspected.

ESD – Electro-Static-Discharge, the sudden transfer or discharge of electricity from one object to another.

ESD Sensitivity – ESD susceptibility. The device’s ability to dissipate the energy of the discharge or withstand the current levels involved.

ESR – Electro-statically applied Solder Resist.

Etch Factor – The ratio of the depth of etch (conductor thickness) to the amount of lateral etch (undercut).

ETCH Resist – An organic ink, lacquer, photo-resist, self-adhesive plastic tape, metal deposit or other material which will prevent specific areas of the metal on a panel from being attacked by an etchant.

Etchant – A solution used to remove, by chemical reaction, the unwanted portion of material from a printed board.

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.

Etch-back – The controlled removal of all resins of base material on the side wall of holes in order to expose internal conductor areas.

Etched Printed Board – A board having a conductive pattern formed by the chemical removal of unwanted portions of the conductive foil.

Etching – Removal of metal from the surface of PCB by chemical dissolution. The process is normally carried out selectively by masking areas of metal which are to be left on the PCB.

Exotherm – The characteristic curve of a resin during cure showing reaction of temperature vs. time.

Extraneous Copper – Unwanted copper remaining on the base material after chemical processing.

Eyelet – A hollow tube inserted in a terminal or printed board to provide mechanical support for component leads or electrical connection.


Fault List – A listing of shorts and opens on a PCB to be repaired.

Feed-through – A plated through-hole in a printed circuit board that is used to provide electrical connection between a trace on one side of the printed circuit board to a trace on the other side. Since it is not used to mount component leads, it is generally a small hole and pad diameter.

Fibre Exposure – A condition in which broken reinforcing fibres of the base material are exposed and protrude in machined or abraded areas.

FICS – Flashscan Image Control Software: A DOS Program which sends Gerber files to the plotter.

Fiducial – A mark both in the artwork and etched with the circuit traces of the PCB. It is used to identify artwork orientation on the board. Global fiducials locate the overall pattern; local fiducials pinpoint component sites, typically fine-pitch.

Fillet – The concave formation of soldified solder between the land or pad and the component lead.

Fine Line Design – Printed circuit design permitting two, and nowadays even three, traces between adjacent dip Pins. It entails the use of photo-imageable solder mask (PISM).

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.

First Pass Yield – The per centage of finished assemblies to pass all tests without re-work.

Fixture – A device that enables interfacing a printed circuit board with a spring-contact probe test pattern.

Flat Cable – A cable with two or more parallel, round or flat, conductors in the same plane encapsulated by an insulating material.

Flexible Printed Wiring – A random arrangement of printed wiring utilizing flexible base material with or without flexible cover layers.

Flexure Failure – A conductor failure due to repeated flexing which is indicated by an increase of resistance to a specified value for a specified time.

Flood Bar – A device on a screen printer that drags solder paste back to the starting point after the squeegee has made a stroke. The return is for set-up of the next stroke as it does no printing on the backstroke.

Flow Soldering – Also called wave soldering. A method of soldering printed circuit boards by moving them over a flowing wave of molten solder in a solder bath.

Fluorocarbon – An organic compound having fluorine atoms in its structure to lend chemical and thermal stability to plastics.

Flush Conductor – A conductor whose outer surface is in the same plane as the surface of the insulating material adjacent to the conductor.

Flux – A substance used to promote or facilitate fusion, such as a material used to remove oxides from surfaces to be joined by soldering welding.

Flux Residue – A flux-related contaminant that is present on or near the surface after soldering and, if possible, should be washed away.

Flux-cored Solder – A wire of solder that contains one or more continuous flux-filled cavities along its length.

Foil – A thin sheet of metal, usually copper, used as the conductor for printed circuits.

Footprint – A set of properly sized and placed pads of a PCB on which a surface mounted component can be placed and soldered. Alternatively, the footprint is the board area occupied by a surface mounted component and its mounting pads. See also Land Pattern.

Forced-air Convection – Convection, consisting of flow, rate, velocity and temperature, as heat transfer of fluid or gas over solder joints to be re-flowed.

FR4 – Flame retardent laminate made from woven glass fibre material impregnated with epoxy resin.

Fully-Additive Process – An additive process wherein the entire thickness of electrically isolated conductors is built-up by copper.

Functional Test – To check an assembly using equipment that tests for the functions intended and engaging inputs and outputs.

Fused Coating – A metallic coating, usually tin or solder alluvia, which has been melted and solidified forming a metallurgical bond to the base material.


Gas Blanket – A flowing inert gas atmosphere used to keep metal from oxidizing.

Gerber – Vector-based language, developed by Gerber Scientific Instrument Company, for sending commands to photoplotters.

GI – Laminate made from woven glass fibre material impregnated with polyimide resin.

Glass Epoxy – A material used to fabricate printed circuit boards. The base material (fibre-glass) is impregnated with an epoxy filler which then must have copper laminated to its outer surface to form the material required to manufacture printed circuit board.

Glob Top – A coating process in which a set portion of resin is dispensed on the top of a chip or board. After spreading over the entire surface ,it is cured to form a soild protective coating.

Go/No-Go Test – Procedure to yield only pass or fail.

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

Grid – An orthogonal network of two sets of parallel, equidistant lines used for locating points on a printed circuit board.

Ground Plane – A conductor layer, or portion of a conductor layer, used as a common reference point for circuit returns, shielding, or heat sinking. All those areas, not consumed by traces or pads, of the PCB which are left unetched and tied to the ground on the board.

Ground Plane Clearance – Removed portions of a ground plane that serves to isolate it form a hole in the base material to which the plane is attached

Guided Probe Method – A technique for volume production of PCBs based on incoming inspection to catch the majority of device failures and inspection prior to populating, that will eliminate most manufacturing errors.

Gull Wing Lead – A surface mounted device lead which flares outward from the device body.


Halides – Compounds containing fluorine, chlorine, bromine or iodine, which may be part of the activators in the flux system and must be cleaned.

Halogenated Polyester – A polyester resin modified with halogens to reduce flammability.

Haloing Mechanically – Induced fracturing or de-lamination on or below the surface of the base material, it is usually exhibited by a light area around holes, other machined areas, or both.

HASL – Hot Air Solder Level. See Solder Leveling.

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.

Heat and Pull – A de-soldering method using a device that grasps, heats and pulls the leads to be removed.

Heat Sink – Any device that absorbs and draws off heat from a hot object, radiating it into the surrounding atmosphere.

Heel,Bonding – The part of a lead adjacent to a termination that has been deformed by the edge of the bonding tool.

Hermetic – Airtight sealing of an object.

Hipot Test – Wherein the assembly or component undergoes a high potential (ac) current.

Hole Breakout – A condition in which a hole is not completely surrounded by the land.

Hole Density – The quantity of holes in a PCB per unit area.

Hole Location – The dimensional location of the centre of a hole.

Hole Pattern – The arrangement of all holes in a printed board.

Hole Pull Strength – The force necessary to rupture a plated through-hole when loaded or pulled in the direction of the axis of the hole.

Hole Void – A void in the metallic deposit of a plated through-hole exposing the base material.

Hot Zone – The section of a re-flow oven held at maximum temperature. Other zones include per-heat and cooling.

Hygroscopic – The ability of a material to absorb and retain moisture from the air.


IC – Integrated Circuit.

Immersion Plating – The chemical deposition of a thin metallic coating over certain basis metals that is achieved by a partial displacement of the basis metal.

Impedance, Characteristic – The resistance of a parallel conductor structure to the flow of alternating current (ac), usually applied to high-speed circuits and normally consisting of a constant value over a wide range of frequencies.

In-Circuit Test – A check of specific components(s) or cuicuits(s) within an assembly without their de-coupling from the primary circuit.

Inclusion – A foreign particle in the conductive layer, plating, or base material.

Indentation – See “Pit”

Index edge – Index edge marker, indexing hole, indexing notch, indexing slot: See Locating Edge, Location Edge Marker, etc.

Initiating – see “activating”.

Inspection Lot – A collection of units of products bearing identification and treated as a unique entity from,which a sample is to be drawn and inspected to determine conformance with the acceptability criteria. Assemblies of a specific production run selected for inspection or test as a sample of the entire run.

Inspection Overlay – A positive or negative transparency made from the production master and used as an inspection aid.

Insulation Resistance – The electrical resistance of the insulating material (determined under specified conditions) between any pair of contacts, conductors, or grounding device in various combinations. The electrical resistance of the insulating material (determined under specified conditions) as measured between any pair of contacts or conductors.

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.

Inter-facial Connection – See Through Connection.

Inter-layer Connection – An electrical connection between conductive patterns in different layers of a multi-layer printed board. (See also Through Connection.)

Internal Layer – A conductive pattern which is contained entirely within a multi-layer printed board.

Interstitial Via Hole – A plated through-hole connecting two or more conductor layers of a multilayer printed board but not extending fully through all the layers of base material comprising the board.

IPC – The Institute for Interconnecting and Packaging Electronic Circuits, an American organization.

Isolation – The clearance around a pad, track, zone or via that defines the nearest approach allowed by conductors of another signal set.


J-leads – The preferred surface mount lead form used on PLCCs, so named because the lead departs the package body near its Z-axis centre-line, is formed down the rolled under the package. Leads so formed are shaped like the letter “J”.

Jumper – An electrical connection between two points on a printed board added after the intended conductive pattern is formed.

Jump-Scoring – similar to v-scoring, this is a process that is used when a printed circuit board is pannelized. 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.

Just-in-time – JIT. Minimization of inventory by supplying material and components to the production line directly before placement into the product.


Kapton – Du Pont trade name for polyimide film.

Key – A device designed to assure that the coupling of two components can occur in only one position.

Keying Slot or Polarizing Slot – A slot in a printed circuit board that polarizes it, thereby permitting it to be plugged into its mating receptacle with pins properly aligned, but preventing it from being reversed or plugged into any other receptacle.

Keyway – A slot used to assure the correct location in a mating connector.

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


Laminate – A product made by bonding together two or more layers of material.

Laminate Presses – Multi-layer equipment that applies both pressure and heat to laminate and prepreg to make multi-layer boards.

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

Laminate Void – Absence of laminate material in an area which normally contains laminate material.

Lamination – The process of manufacturing a laminate; also the process used for application of a dry film photo-resist.

Land – On a PCB, the conductive area(s) to which components are attached. Also see Pad.

Land Pattern – A combination of lands that is used to mount, interconnect and test a particular component.

Landless Hole – A plated through-hole without a land(s).

Laser – Light Amplified by Stimulated Emission of Radiation.

Layer – One in a series of levels in a board on which tracks are arranged to connect components. Vias connect tracks and zones between layers.

Layer-to-Layer Spacing – The thickness of dielectric material between adjacent layers of conductive circuitry in a multi-layer printed circuit board.

LCCC – Leadless ceramic chip carrier.

Lead – A terminal on a component. Pronounced “Leed”

Lead Mounting Hole – See Component Hole.

Lead Projection – The distance that a component lead protrudes through the side of a board that is opposite from the one upon which the component is mounted.

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 board, e.g. Part number, component locations, and patterns.

Lifted Land – A land that has fully or partially separated (lifted)from the base material, whether or not any resin is lifted with land.

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”.

Liquation – If a solder alloy with a long melting range is heated too slowly. the phase with the lowest melting point begins to flow first. The material left behind has a changed composition and a higher melting point and will not flow readily. An unsound and unsightly joint is the usual result of liquation.

Liquids – The lowest temperature at which filler metal (solder) is completely liquid.

Load Test – A mass re-flow soldering system test for the capacity repeatedly to process boards regardless of their volume though the oven.

Locating Edge, Locating Hole, Locating Notch, Locating Slot – A physical feature in a panel or printed board used to position the board or mounted components accurately. A hole, notch or slot in the panel or printed board to enable it to be positioned accurately during manufacture and/or assembly. Synonyms: fabrication hole (or notch or slot), indexing hole, location hole, manufacturing hole, outrigger hole, tolling hole.

Logic diagram – A drawing that depicts the multi-state device implementation of logic functions with logic symbols and supplementary notations, showing details of signal flow and control, but not necessarily the point-to-point wiring.

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


Major Defect – A defect that could result in failure or significantly reduce the usability of the part for its intended purpose.

Manhattan Distance – The orthogonal distance between two points.

MAR – Minimum Annular Ring. The minimum metal width, at the narrowest point between the circumference of the hole and the outer circumference of the land. This measurement is made to the drilled hole on internal layers of multi-layer printed circuit board to the edge of the plating on outside layers of multi-layer boards and double-sided boards.

Margin – The distance between the reference edge of a flat cable and the nearest edge of the first conductor.(See also Edge Spacing)

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

Mass Soldering – Methods of soldering in which many joints are made in the same operation.

Master Artwork – A document showing dimensional limits and grid locations for all parts of an assembly to be fabricated. It includes the arrangement of conductors and non-conductive patterns and the size, type and location of holes.

Master Drawing – A document that shows the dimensional limits or grid locations applicable to any or all parts of a printed board(rigid or flexible),including the arrangement of conductive and non-conductive patterns or elements; size, type and location of holes.

Master Pattern – An accurately scaled pattern which is used to produce the printed circuit within the accuracy specified on the master drawing.

Maximum, Plated Through-hole Size – A hole size equal to the specified hole size before plating, plus the manufacturing tolerance, less twice the minimum plating thickness.

MCR – Moulded Carrier Ring. A tape of fine-pitch chip package named for the method of supporting and protecting the leads. The leads are left straight; the ends of the leads are embedded in a strip of plastic, which is the Moulded Carrier Ring.

Mean Time between Failure – MTBF. The statistical mean average time interval, usually in hours, that may be expected between failures of an operating unit. Results should be designated actual. Predicted or calculated.

Measling – A condition existing in the base laminate in the form of discrete white sports or crosses below the surface of the base laminate, reflecting a separation of fibres in the glass cloth at the weave intersection.

MELF – A metal electrode leadless face surface mount component that is round with metallic cap terminations.

Melting Range – The temperature range over which the solder alloy melts. An alloy with a single melting point, rather than a melting range, is known as a eutectic alloy.

Meniscus – The contour or shape of molten solder as formed by surface tension forces in turn controlled by wetting.

Metal Clad Base Material – Base material covered with metal on one or both of its sides.

Metallization – A deposited or plated thin metallic film used for its protective or electrical properties.

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.

Micro-sectioning – A destructive test procedure in which a section of specimen it cut and removed for close examination.

Micro-strip – A type of transmission line configuration which consists of a conductor over a parallel ground plane, and separated by a dielectric.

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.

Mil – One thousandth (0.001) of an inch. Not to be confused with Mil (short for millimetre). 1 Inch = 25.4 mm; 1 mil = 0.0254 mm.

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.

Minimum Electrical Spacing – The minimum allowable distance between adjacent conductors that is sufficient to prevent dielectric breakdown, between the conductors at any given voltage.

Minor Defect – A defect which is not likely to reduce the usability of the unit for its intended purpose, It may be a departure from established standard having no significant bearing on the effective use or operation of the unit.

Mis-registration – The lack of dimensional conformity between successively produced features or terns.

Mixed Component-Mounting Technology – A component mounting technology that uses both through-hole and surface-mounting technologies on the same packaging and interconnecting structure.

Modifier – A chemically inert substance added to a resin to change its properties.

Module – A separable unit in a packaging scheme displaying regularity of dimensions.

Mother Board – Also called back plane, or matrix board. A relatively large printed circuit board on which modules, connectors, sub-assemblies or other printed circuit boards are mounted and inter connections made by means of traces on the board.

Mounting Hole – A hole used for the mechanical mounting of a printed board or for the mechanical attachment of components to the printed board.

Muffle – An enclosure that is located between the heating elements and the parts being processed that contains the atmosphere required for the re-flow soldering process.

Multilayer Printed Boards – Printed circuit boards consisting of three or more conducting circuit planes separated by insulating material and boned together with internal and external connections of the circuitry as required.

Multimeter – A portable test instrument which can be used to measure voltage, current and resistance.

Multiple-image Production Master – A production master used in the process of making two or more printed boars simultaneously.


Nail Heading – The flared condition of copper on the inner conductor layers of a multi-layer board usually caused by hole drilling.

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

Negative (Noun) – An artwork, artwork master, or production master in which the intended conductive pattern is transparent to light, and the areas to be free from conductive material are opaque.

Negative–acting Resist – A resist which is polymerized (hardened) by light and which, after exposure and development remains on the surface of a laminate in those areas which were under the transparent parts of a production ,master.

Netlist – A net is a junction of component nodes. A netlist is a collection of nets that define all the connections in a circuit. It is obtained automatically from a schematic capture program.

Neutralizer – An alkaline chemical added to water to improve its ability to dissolve flux residues.

NFP – Non-functional pad.

Node – A pin, lead or even junction which will have at least one wire connected to it.

Non-clean solder – A process using specially formulated low-solid solder pastes whose residues require no cleaning.

Non-conductive Epoxy – An epoxy resin with or without a filler, which may be added to improve thermal conductivity.

Non-conductive Pattern – A configuration formed by functional non-conductive material of a printed circuit.

Non-functional Land – A land on internal or external layers, not connected to the conductive pattern on its layer.

Non-polar Compound – Material having electrical charges distributed over the surface of the molecule, thereby showing an electrical effect in solution.

Non-wetting – A condition whereby a surface has contacted molten solder, but has had none of the solder adhere to it.

NPTH – Non-plated trough-hole.


Omegameter – A test instrument measuring ionic residues on PCBs via the drop of resistivity over a specific time.

One-sided Board – See Single-sided Board.

Open – An area of a bare PCB which, due to over-etching or fabrication problems, separates two electrically connected points.

Organic Activated – OA. A water-soluble flux using organic acids as activators.

OSP – Organic Solderable Preservative.

Outgassing – The gaseous emission from a laminate printed board or component when the board or the printed board assembly is exposed to heat or reduced air pressure or both.

Outgrowth – The increase in conductor width at one side of a conductor, caused by plating build-up, over that delineated on the production master.

Overhang – Increase in printed circuit conductor width caused by plating build-up or by undercutting during etching.


Packaging Density – Quantity of functions (components, interconnection devices, mechanical devices) per unit volume, usually expressed in qualitative terms, such as high, medium, or low.

Pad – A portion of the conductive area of which components, terminals, traces, etc., are mechanically attached. Also see land.

Panel – The base material containing one or more circuit patterns that passes successively through the production sequence and from which printed circuit boards are extracted. See Backplanes / Backpanels.

Panel Plating – The plating of the entire surface of a panel (including holes).

Parylene – A polymer resin (Polyparaxylense) that provides a thin, uniform coating on PCBs and components. It can be applied via vacuum for deposition on sharp edges and complex shapes.

Pattern – The configuration of all conductive and/or non-conductive areas on a PCB. Letters and inscription may also be included. Pattern also denotes the circuit configuration on related tools, drawing and masters. Synonym: image

Pattern Plating – Selective plating of a conducive pattern.

PCB – Printed Circuit Board.

PCMCIA – Personal Computer Memory Card International Association.

PEC – Printed Electronic Component.

Peel Strength – The force per unit width required to peel the conductor or foil from the base material.

Permanent Mask – A resist which is not removed after processing, e.g., plating resist used in the fully-additive process.

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.

Photomaster – See Artwork Master.

Photoplotter – A plotter that writes using light.

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

Photopolymer – A polymer that changes characteristics when exposed to light of a specific frequency.

Physical Layer – A conductive board layer or artwork image representing a complete conductive layer.

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.

Pick-and-place Machine – A programmable machine usually with a robot arm for picking components from a feeder. It moves the part for placement and/or insertion to a specific site on the board.

PIH Assembly – Pin-in-hole a printed board assembly made up of components with leads which pass through holes in the board and lands. Synonyms: traditional assembly, conventional assembly.

Pilot Hole – See Locating Hole.

Pin – A terminal on a component. A component lead that is not readily formable without being damaged.

Pin Density – The quantity of pins on a printed board per unit area.

Pinhole – A minute hole through a layer of pattern.

Pinholes – Small imperfection which penetrate entirely through the conductor and/or solder.

Pink Ring – Chemically-induced fracturing or de-lamination on or below the surface of the base material; it is usually exhibited by a light area around holes, other etched areas or both.

Pit – A depression in the conductive layer that does not penetrate entirely through it.

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

Pitting – Small holes or sharp edges on the surface of a solder joint generally caused by flux entrapment, oxidation or over-heating.

Plastic Leaded Chip Carrier – PLCC. A component package with J-leads.

Plate Finish – Pertaining to Laminating. The finish present on the metallic surface of metal clad base material resulting from direct contact with the laminating press plates without modification by any subsequent finishing process.

Plated Through-hole – A hole with the deposition of metal (usually copper) on its sides to provide electrical connections between internal or external conductive patterns.

Plating – A uniform coating of conductive metal upon the base material of the printed circuit board.

Plating Bar – The temporary conductive path interconnecting areas of a printed board to be electroplated, usually located on the panel outside the borders of such a board.

Plating Resists – Materials which, when deposited on conductive areas, prevent the plating of the covered areas. Resists are available both as screened-on materials and as dry-film photopolymer resists.

Plating Up – The process consisting of the electrochemical deposition of a conductive material on the base material (surface holes, etc.) after the base material has been made conductive.

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

Plotting – The practice of mechanically converting X – Y position information into a visual pattern, such as artwork.

Poise – A centimeter-gram-second unit of viscosity equal to that of a fluid requiring a shearing force of one dyne to move from a square centimeter area which a velocity of one centimeter per second (cps).

Polarization – A technique of eliminating symmetry within a plane so that parts can be engaged in only one way in order to minimize the possibility of electrical and mechanical damage or malfunction.

Polyester – (mylar) low melting point plastic film used for cheap flexible circuits.

Polyimide – Higher melting point plastic film used as base for flexible portions of flexi-rigid boards as well as for many flexible circuits.

Polyimide Resins – High temperature thermoplastics used with glass to produce printed circuit laminates from multi-layer and other circuit applications requiring high temperature performance.

Populated PCB – A printed board on to which all passive and active components have been assembled. Synonyms: printed board assembly (PBA), card, assembled board.

Positive (noun) – An artwork, artwork master, or production master in which the intended conductive pattern is opaque to light, and the areas intended to be free from conductive material are transparent.

Positive-acting Resist – A resist which is decomposed (softened) by light and which, after exposure and development, is removed from those areas which were under the transparent parts of a production master.

Pre-heat – The process portion of the re-flow heat curve in which the PCB is heated from ambient at a pre-set rate and prior to full liquidus at the solder joint areas.

Prepreg – Sheet material consisting of the base material impregnated with a synthetic resin, such as epoxy or polymide, partially cured to the B-stage.

Press-fit Contact – An electrical pin contact which can be pressed into a hold in a printed board to make immediate contact.

Primer – A coating applied before the application of an adhesive to improve the bond.

Printed Board – The general term for completely processed printed circuit or printed wiring configuration. It includes signle, double, and multi-layer boards, both rigid and flexible.

Printed Board Assembly – A printed board with electrical or mechanical components, other printed boards, or a combination of there, attached to it with all manufacturing processes, soldering, coating, etc. Completed.

Printed Circuit – A conductive pattern that comprises printed components, 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 Circuit Assembly – A printed circuit board to which discrete components; hardware, and other electronic devices have been attached to form a complete operating unit.

Printed Component – A component part, such as an inductor, resistor, capacitor, or transmission line, which is formed as part of the conductive pattern of the printed board.

Printed Contact – A portion of conductive pattern formed by printing, serving as one part of a contact system.

Printed Wiring – A conductive pattern within or bonded to the surface of a base material intended for point-to-point connection of separate components and not containing printed components.

Printed Wiring Assembly Drawing – A document that shows the printed board (rigid or flexible), the separately manufactured components which are to be added to the board, and any other information necessary to describe the joining of these parts to perform a specific function.

Printed Wiring Board – See Printed Board.

Printed Wiring Layout – A sketch that depicts the printed wiring substrate, the physical size and location of electronic and mechanical components, and the routing of conductors that electrically interconnect components, in sufficient details to allow the preparation of documentation and artwork.

Probing Systems – Equipment for making electrical contact between the bare PCB, components or assemblies and the continuity tester. Probling devices range from manual units for low volumes to computer-controlled systems.

Process Indicator – A detectable anomaly, other than a defect, that is reflective of material, equipment, process and/or workmanship variations.

Production Master – A 1 to 1 (1:1) scale pattern which is used to produce one or more printed boards (rigid or flexible) within the accuracy specified on the master drawing.

PTH – 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.

Pull Strength – See Bond Strength.

PWB – Printed Wiring Board; same as PCB.


Radial Lead – A lead extending out of the side of a component, rather than from the end.

Reference Edge – The edge of cable or conductor from which measurements are made.

Re-flow Soldering – Joining components to substrates by placing the parts into solder paste and then melting the paste to achieve re-flow and the interconnection.

Re-flow Spike – The portion of the re-flow soldering process during which the temperature of the solder is raised to a value that is sufficient to cause the solder to melt.

Re-flowing – The melting of an electro-deposit followed by solidification.

Register Mark – A symbol used as a reference point to maintain registration.

Registration – The alignment of a pad on one side of the printed circuit board or layers of a multi-layer board to its mating pad on the opposite side.

Relative Humidity – The radio of the quantity of water vapour present in the air to the quantity which would saturate the air at the given temperature.

Reliability – The probability that a component, device or assembly will function properly for a defined period of time under the influence of specific environment and operational conditions.

Repair – The process of restoring the functional capability of a defective component or circuit.

Repeatability – The ability of a system to return to a specific parameter, said of equipment when evaluating its consistency of processing.

Residue – Any visual or measurable form of process-related contamination.

Resin – A high-molecular-weight organic material with no specific melting point. A polymer.

Resin Smear – Resin transferred from the base material onto the surface or edge of conductive pattern normally caused by drilling. Sometimes called epoxy smear.

Resist – Coating material used to mask or to protect selected areas of a pattern from the action of an etchant, solder, or plating. Also see Dry Film, Resists, Plating Resists and Solder Resists.

Reverse Image – The film pattern on a printed circuit board enabling the exposure of conductive areas for subsequent plating.

Re-work – A manufacturing step or process that is repeated to bring a non-performing or non-conforming component or circuit to a functional condition.

Re-working – The act of repeating one or more manufacturing operations for the purpose of improving the yield of acceptable part.

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.

Rheology – Science of flow ,is the study of the flow and deformation of matter and is particularly important with regard to colloidal systems.

Ribbon Cable – A flat cable with round conductors.

Right-angle Edge connector – A connector which terminates conductors at the edge of a printed board, which bringing the terminations our at right angles to the plane of the board conductors.

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.

Roadmap – A printed pattern of non-conductive material by which the circuitry and components are delineated on a board to aid in service and repair of the board.

Rosin – A hard, natural resin (nowadays also synthetic),consisting of abietic and primaric acids and their isomers, some fatty acids and terpene hydrocarbons, that is extracted from pine trees and subsequently refined.

Rosin Flux – The mildest of solder fluxes and generally requiring added organic activating agents.

Route – or Track. A layout or wiring of an electrical connection.


Saponifier – An aqueous organic or inorganic base solution with additives that promote the removal of flux.

Schematic Diagram – A drawing that shows, by means of graphic symbols, the electrical connections, components and functions of a specific electronic circuit arrangement.

Screen – A network of metal or fabric standards mounted tautly on a frame and upon which the PCB’s circuit pattern is superimposed by photographic means.

Screen Printing – A process for transferring an image to a surface by forcing suitable media through a stencil screen with a squeegee. Also called silk screening

Semi-additive process – A process for obtaining conductive patterns by a combination of electroless metal deposition with etching and/or electroplating. A semi-additive process is used in conjunction with a metal clad base material.

Semi-aqueous Cleaning – A technique involving the use of a solvent followed by hot-water rinses and drying.

Sensitizing – See Activating.

Shadowing – A condition occurring during etching in which the dielectric material, in intimate contact with the foil, is incompletely removed though acceptable etching may have been achieved elsewhere. In re-flow soldering, a condition in which component bodies block the infra-red energy from certain areas of the board. In wave soldering, the solder fails to wet some parts leads due to other devices blocking the flow of solder.

Shielding, Electronic – A physical barrier, usually electrically conductive, designed to reduce the interaction of electric or magnetic fields upon devices, circuits or portions of circuits.

Shingle-sided Board – A printed board with a conductive pattern on one side only.

Short – Short-circuit, An abnormal connection of relatively low resistance between two points of a circuit or conductors from different nets either touch or some closer than the minimum spacing allowed for the design rules being used.

Signal – An electrical impulse of a pre-determined voltage, current, polarity and pulse width.

Signal Conductor – An individual conductor used to transmit an impressed signal.

Signal Plane – A conductor layer intended to carry signals, rather than serve as a ground or other fixed voltage function.

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

Silkscreen – Often used for legend print and means the printed reference designators on a printed wiring boards.

Simulation – The process of creating a virtual representation(a computer model)of an electronic component, circuit board, or system and applying virtual test signals to the model to verify its functionality and possibly its timing.

Single-image Production Master – A production master used in the process of making a single printed board.

Slump – A spreading of the solder paste after printing but before re-flow soldering. If excessive, a loss of definition may result.

Small Outline Integrated Circuit – SOIC. An integrated circuit with two parallel rows of pins in surface mount package.

SMD – Surface Mounted Device. Any component or hardware element designed to be mounted to a printed circuit board (PCB) without penetrating the board.

Smear – Resin, smeared over the edge of an internal copper layer of a multi-layer board during drilling, which prevents the layer from making electrical contact with the barrel of the hole.

SMOBC – Solder Mask Over Bare Copper.

SMT – Surface Mount Technology. Defines the entire body of processes and components which create printed circuit assemblies without components with leads that pierce the board.

Snap-off – The return of a stencil to normal level after deflection by the pressure of the squeegee moving across the surface.

Snap-off Distance – The space between the top surface of the substrate and the underside of the stencil when the squeegee is not in play.

Soak – The period after pre-heat and before re-flow peak temperature where the internal temperature differences between parts allowed to equalize.

Solder – A metal alloy with a melting temperature that is below 450℃.

Solder Bridging – The unwanted formation of a conductive path of solder between conductors.

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

Solder Connection Pinhole – A small hole that penetrates from the surface of a solder connection to a void of indeterminate size within the solder connection (process indicator).

Solder Fillet – A preferable concave surface of solder that is at the interconnection of the metal surfaces of a solder connection.

Solder Levelling – The process of immersing printed circuit boards into hot liquids. Often referred to as HASL or HAL (Hot Air Levelling).

Solder Mask, Solder Resist – Coating with mask and insulate areas of a circuit pattern where solder is not desired.

Solder Masks – A screening defect characterized by prints having jagged edges, the result of incorrect moving pressure.

Solder oil (Blanket) – Liquid formulations that are used in intermix wave soldering and as coverings on static and wave soldering pots in order to eliminate dross and to reduce surface tension during the soldering process.

Solder Paste – Finely divided particles of solder, with additives to promote wetting and to control viscosity, tackiness, drying rate, etc.

Solder Plug – A core of solder in a plated through-hole.

Solder Projection – An undesirable protrusion of solder from a solidified solder joint or coating.

Solder Resist – An ink, lacquer, photo-resist or metal coating which is not wetted by molten solder. It is applied to specific areas of a PCB to stop them from being solder-coated, usually when mass soldering.

Solder Side – The side of a printed board which is opposite to the component side.

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

Solderability – The ability of a metal to be wetted by molten solder.

Solderability Testing – The evaluation of a metal to determine its ability to be wetted by solder.

Soldering – A process of joining metallic surfaces with solder, without the melting of the base metals.

Soldering Iron Tip – The portion of a soldering iron that is used for the application of the heat that melts the solder.

Solderless Wrap – A method of connecting a solid wire to a square, rectangular, or V-shaped terminal by tightly wrapping the wire around the terminal with a special tool.

Solidus – The highest temperature at which filler metal(Solder) is completely solid.

Spurious Signal – See Cross-talk.

Stamped Printed Wiring – Wiring which is produced by die stamping and which is bonded to an insulating base.

Statistical Process Control – SPC. The use of statistical techniques to analyse the outputs of processes with the results guiding actions taken to adjust and/or maintain a state of quality control.

Step Soldering – The making of solder connections by sequentially using solder alloys with successively lower melting temperatures.

Step-and-repeat – A method by which successive exposures of a single image are made to produce a multiple-image production master.

Straight-through Lead – A component lead that extends through a hole and is terminated without subsequent forming.

Strain – The deformation resulting from a stress.

Stripline – A type of transmission line configuration which consists of a single narrow conductor parallel and equidistant to two parallel ground planes.

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.

Subtractive Process – A process for obtaining conductive patterns by selective removal of unwanted areas of conductive foil from a metal clad base material.

Supported Hole – A hole in a printed board that has its inside surface plated or otherwise reinforced.

Surface Insulation Resistance – SIR. A measure in ohms of an insulating material’s (as in FR-4) electrical resistance between conductors.

Surface Insulation Resistance Test – Test for the level of resistance of an insulating material, such as FR-4. Between conducting members of a board (traces, contacts).

Surface Leakage – The passage of current over the boundary surface of an insulator as distinguished from passage through its volume.

Surface Mounting – The electrical connection of components to the surface of a conductive pattern that does not utilize component holes.

Surface Tension – The natural, inward, molecular attraction force that inhibits the spread of a liquid at its interface with a solid material.

Surfactant – A chemical added to the cleaning solution to lower surface tension and to promote wetting.

Swaged Lead – A component lead wire that extends through a hole in a printed board and its lead extension is flattened(swaged)to secure the component to the board during manufacturing operations.


Tape-and-reel – A packaging method of housing surface-mount parts in their own tape cavities in a long continuous strip. The cavities are covered so that the tape can be wound around a reel for convenient handling and machine set-up.

Taped Components – Components attached to continuous tape for automatic assembly.

Teflon – Du Pont trade name as an inventor for PTFE (Polytetrafluoroethylene).

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.

Temperature Profile – The depiction of the temperature that a selected point traverses as it passes through the re-flow process.

Tented Via – A via with solder mask completely covering both its pad and its plated through-hole. This completely insulates the via from foreign objects, thus protecting against accidental shorts, but it also renders the via unusable as a test point.

Tenting – A printed board fabrication method of covering over plated through-holes and the surrounding conductive pattern with a resist, usually dry film.

Terminal Area – A portion of a conductive pattern usually, but not exclusively, used for the connection and/or attachment of components.

Termination – The part of component that makes contact with a pad on a substrate.

Terpenes – Turpentine. A solvent used in cleaning electrical assemblies.

Test Board – A printed board suitable for determining acceptability of the board or of a batch of boards produced with the same process so as to be representative of the production board.

Test Coupon – A pattern as an integral part of the PCB on which electrical tests may be made to non-destructively evaluate process control. A portion of a circuit used exclusively to functionally test the circuit as a whole.

Test Fixture – A device that adapts a specific assembly under test system via inter-connection.

Test Pattern – A pattern used for inspection or testing purposes.

Test Point – Special points of access to an electrical circuit, used for testing purposes.

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.

Thermocouple – A device made of two dissimilar metals which, when heated, generate a voltage that is used to measure temperatures.

Thermoplastic – A plastic set into final shape by forcing the melted polymer into a cooled mould. The hardened form can be re-melted several times.

Thermoset – A plastic cured or hardened by heating into a permanent shape. Thermosets cannot be re-melted.

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.

Through Connection – An electrical connection between conductive patterns on opposite sides of an insulating base, e.g. plated through-hole or clinched jumber wire.

Tinning – The application of molten solder to a basis metal in order to increase its solderability.

Tombstoning – A soldering defect in which a chip component moves into a vertical position during solidification of the solder so that only one terminal is connected. It is caused by defective re-flow processing.

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.

Trace – A single conductive path in a conductive pattern.

Traces – The metallic conductive strips that provide connections between components, terminals, etc., on printed circuits.

Transmission Cable – Two or more transmission lines.

Transmission Line – A signal-carrying circuit composed of conductors and dielectric material with controlled electrical characteristics used for the transmission of high-frequency or narrow-pulse type signals.

Triazine – Dielectric material with higher glass transition temperature and better thermal stability than epoxy resin, however, more expensive and not in common use.

Trim Lines – Lines which define the borders of a printed board.

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 – The deformation of a rectangular sheet, panel or printed board, that occurs parallel to a diagonal across its surface in such a way that one of the comers of the sheet is not in the plane formed by the other three corners.


UL – Underwriter’s Laboratories, Inc., a corporation for the purpose of establishing safety standards on types of equipment or components in USA and Canada.

Ultrasonic Soldering – Fluxless soldering wherein molten solder is vibrated at ultrasonic frequencies while making the joint.

Undercut – A groove or excavation at one edge of a conductor caused by etching.

Underwriters Symbol – A logotype authorized for placement on a product which has been recognized (accepted) by Underwriters Laboratories, Inc. (UL).

Unsupported Hold – A hole containing no conductive material nor any other type of reinforcement.

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.


Vacuum Pick-up – A component handling tool with a small vacuum cup for ease of pick-up and removal during de-soldering.

Vapour Phase – The solder re-flow process that uses a vaporized solvent as the source for heating the solder beyond its melting point,creating the component-to-board solder joint.

Via – A plated through-hole used as an interlayer connection and not as a terminating point for a component lead. It may also be blind (incomplete penetration) or buried (non-surfacing).

Via Hole – A plated through-hole whose only purpose is to connect a track on one layer or side of the board through to a track on another layer or side. In a via, there is no intention to insert a component lead or other reinforcing material.

Virtual Prototype – A virtual (computer model) representation of an electronic product that can be used to explore different design scenarios and then verify that the product will work as planned before building a physical implementation.

Viscosity – The property of a fluid that enables it to develop and maintain a level of shearing stress dependent upon the velocity of flow and then offer continued resistance to flow. The absolute unit of viscosity measurement is poise, or more commonly, centipoise.

Void – The absence of any substances in a localized area.

Voltage Plane – A conductor or portion of a conductor layer on or in a printed board which is maintained at other than ground potential. It can also be used as a common voltage source, for heat sinking, or for shielding.


Wave Exposure – A surface condition of base material in which the unbroken fibres of woven glass cloth are not completely covered by resin.

Wave Soldering – The technique of joining parts to a PCB by passing the assembly over a wave of molten solder so as to coat the pre-fluxed areas to be joined.

Weave Exposure – A condition of base material in which a weave pattern of glass cloth is appearing on the surface though the unbroken fibres of the woven cloth are completely covered with resin.

Wetting – The formation of a relatively uniform, smooth, unbroken and adherent film of solder to a base material.

Whisker – A needle-shaped metallic growth on a PCB.

Wicking – Capillary absorption of liquid along the fibres of the base material.


Yield – The ratio of usable parts at the end of a manufacturing process to the number of components submitted for processing.


Z-Stroke – The movement of the head of a component placement machine in the vertical place for parts orientation and insertion.


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