Since 1995, Assembling Dependable Engineering, Design, & Manufacturing Relationships

PCB & PCBA Glossary

Electronics Glossary of PCB & PCBA

Below is a helpful reference sheet of key terms and definitions of the PCB or PCBA manufacturing process. At Optima Technology Associates, Inc. we have over 25 years of experience manufacturing PCBs, PCBAs and providing engineering services to help you meet your quality standards and expectations. Contact us today to learn more about working together on your next project.


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

Additive Process

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

Annular Ring

The conductive material completely surrounding a hole.


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


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

Artwork Master

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

Aspect Ratio

The ratio of the PCB thickness to the diameter of the smallest hole.


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

Automatic Test Equipment

Equipment that automatically analyzes functional or static parameters in order to evaluate performance.

B-Stage Material

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

B-Stage Resin

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


The cylinder formed by plating through a drilled hole.

Base Copper

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

Base Material

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

Base Material Thickness

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

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).


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

Blind Via

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


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

Bond Strength

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


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

Buried Via

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


A ridge left on the outside copper surface after drilling.


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


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


A broken corner to change a sharp edge.

Circuit Layer

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

Clad Or Cladding

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

Component Hole

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

Component Side

The side of the circuit board on which most of the components will be located.


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

Conductor Spacing

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

Conductor Thickness

The thickness of the conductor including all metallic coatings.

Conformal Coating

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

Connector Area

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

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.


Process Capability index ('equivalent') taking account of off-centredness


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


Process of removing burrs after PCB drilling.


Any nonconformance to specified requirements by a unit or product.


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


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

Design Rule

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

Design Rule Check

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


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


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.


An insulating medium which occupies the region between two conductors.


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

Dimensional Stability

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

Double-Sided Board

A printed board with a conductive pattern on both sides.

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.

Electroless Copper

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


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


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

Epoxy Smear

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


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.


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

First Article

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

Ground Plane

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

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.

Hole Breakout

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

Hole Pattern

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

Insulation Resistance

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


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

Laminate Thickness

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

Laminate Void

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


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


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


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".

Major Defect

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


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


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


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.

Minor Defect

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

Multilayer Printed Boards

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


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


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


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

Pattern Plating

The selective plating of a conductive pattern.

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.


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

Plated Through Hole

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

Plating Void

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


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


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

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 Wiring Board

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


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


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

Resin (Epoxy) Smear

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


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


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.

Screen Printing

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

Single-Sided Board

A printed board with conductive pattern on one side only.


Soldermask Over Bare Copper finish


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

Solder Mask

Non-preferred term for solder resist.


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


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.

Test Coupon

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


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.

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.


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

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.


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


The absence of any substances in a localized area.

Wave Soldering

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


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