PCB definitions


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).
Bleeding
A condition in which a plated hole discharges process materials of solutions from voids and crevices.
Blind Via
A conductive surface hole that connects an outer layer with an inner layer of a multi layer board without penetrating the entire board.
Blister
A localized swelling and separation between any of the layers of a laminated base material, or between base material or conductive foil. It is a form of delamination.
Bond Strength
The force per unit area required to separate two adjacent layers of a board by a force perpendicular to the board surface.
Bow
The deviation from flatness of a board characterized by a roughly cylindrical or spherical curvature such that if the board is rectangular, its four corners are in the same plane.
Buried Via
A via hole that does not extend to the surface of a printed board.
Burr
A ridge left on the outside copper surface after drilling.
C-Stage
The condition of a resin polymer when it is in a solid state with high molecular weight. Being insoluble and infusion.
Capacitance
The property of a system of conductors and dielectrics which permits storage of electricity when potential difference exists between conductors.
Chamfer
A broken corner to eliminate an otherwise sharp edge.
Circuitry Layer
A layer of a printed board containing conductors, including ground and voltage planes.
Clad Or Cladding
A relatively thin layer or sheet of metal foil that is bonded to a laminate core to form the base material for printed circuits.
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.
Conductor
A thin conductive area on a PCB surface or internal layer usually composed of lands (to which component leads are connected) and paths (traces).
Conductor Spacing
The distance between adjacent edges (not centerline to centerline) of isolated conductive patterns in a conductor layer.
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.
Cpk
Process Capability index (‘equivalent’) taking account of off-centredness
Cte
Coefficient of thermal expansion. The measure of the amount a material changes in any axis per degree of temperature change.
Deburring
Process of removing burrs after PCB drilling.
Defect
Any nonconformance to specified requirements by a unit or product.
Definition
The fidelity of reproduction of pattern edges, especially in a printed circuit relative to the original master pattern.
Delamination
A separation between any of the layers of the base of laminate or between the laminate and the metal cladding originating from or extending to the edges of a hole or edge of board.
Design Rule
Guidelines that determine automatic conductor routing behavior with respect to specified design parameters.
Design Rule Checking
The use of a computer program to perform continuity verification of all conductor routing in accordance with appropriate design rules.
Desmear
The removal of friction-melted resin and drilling debris from a hole wall.
Dewetting
A condition that results when molten solder has coated a surface and then receded, leaving irregularly shaped mounds separated by areas covered with a thin solder film and with the base material not exposed.
Dielectric
An insulating medium which occupies the region between two conductors.
Digitizing
The converting of feature locations on a flat plane to a digital representation in X-Y coordinates.
Dimensional Stability
A measure of the dimensional change of a material that is caused by factors such as temperature changes, humidity changes, chemical treatment, and stress exposure.
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).
Electroplating
The electro deposition of an adherent metal coating on a conductive object. The object to be plated is placed in an electrolyte and connected to one terminal of a D.C. voltage source. The metal to be deposited is similarly immersed and connected to the other terminal.
Epoxy
A family of thermosetting resins used in the packaging of semiconductor devices. Epoxies form a chemical bond to many metal surfaces.
Epoxy Smear
Epoxy resin which has been deposited on edges of copper in holes during drilling either as uniform coating or in scattered patches. It is undesirable because it can electrically isolate the conductive layers from the plated-through-hole interconnections.
Etchback
The controlled removal of all components of the base material by a chemical process acting on the sidewalls of plated-through holes to expose additional internal conductor areas.
Etching
The chemical, or chemical and electrolytic, removal of unwanted portions of conductive materials.
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.
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.
Ist
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.
Kgb
Known good board or assembly. Also known as a golden board.
Laminate
The plastic material usually reinforced by glass or paper that supports the copper cladding from which circuit traces are created.
Laminate Thickness
Thickness of the metal-clad base material, single or double sided, prior to any subsequent processing.
Laminate Void
An absence of epoxy resin in any cross-sectional area which should normally contain epoxy resin.
Land
The portion of the conductive pattern on printed circuits designated for the mounting or attachment of components. Also called land
Legend
A format of lettering or symbols on the printed circuit board; e.g., part number, serial number, component locations and patterns.
Line
A thin conductive area on a PCB surface or internal layer usually composed of lands (to which component leads are connected) and paths (traces). Also known as a “conductor”.
Major Defect
A defect that is likely to result in failure of a unit or product by materially reducing its usability for its intended purpose.
Mask
A material applied to enable selective etching, plating, or the application of solder to a PCB.
Measling
Discrete white spots or crosses below the surface of the base laminate that reflect a separation of fibers in the glass cloth at the weave intersection.
Microsectioning
The preparation of a specimen of a material, or materials, that is to be used in metallographic examination. This usually consists of cutting out a cross-section followed by encapsulation, polishing, etching, and staining.
Microvia
Usually defined as a conductive hole with a diameter of 0.006 in or less that connects layers of a multilayer PCB. Often used to refer to any small geometry connecting hole the creation of which is beyond the tradition practical drilling capabilities.
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.
Pad
The portion of the conductive pattern on printed circuits designated for the mounting or attachment of components. Also called land.
Panel
A rectangular sheet of base material or metal-clad material of predetermined size that is used for the processing of printed boards and, when required, one or more test coupons.
Pattern
The configuration of conductive and nonconductive materials on a panel or printed board. Also, the circuit configuration on related tools, drawings and masters.
Pattern Plating
The selective plating of a conductive pattern.
Photo Print
The process of forming a circuit pattern image by hardening a photosensitive polymeric material by passing light through a photographic film.
Photographic Image
An image in a photo mask or in an emulsion that is on a film or plate.
Photoplotting
A photographic process whereby an image is generated by a controlled light beam that directly exposes a light-sensitive material.
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.
Plotting
The mechanical converting of X-Y positional information into a visual pattern such as artwork.
Prepreg
Sheet material (e.g., glass fabric) impregnated with a resin cured to an intermediate stage (B-stage resin).
Printed Board
The general term for completely processed printed circuit or printed wiring configurations. It includes single, double-sided, and multilayer boards, both rigid and flexible.
Printed Circuit
A conductive pattern that comprises printed components, 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.
Reflowing
The melting of an electrodeposited tin/lead followed by solidification. The surface has the appearance and physical characteristics of being hot-dipped.
Registration
The degree of conformity to the position of a pattern, or a portion thereof, a hole, or other feature to its intended position on a product.
Resin (Epoxy) Smear
Resin transferred from the base material onto the surface of the conductive pattern in the wall of a drilled hole.
Resist
Coating material used to mask or to protect selected areas of a pattern from the action of an etchant, solder or plating.
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.
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.
Smobc
Soldermask Over Bare Copper
Smt
Surface Mount Technology. Defines the entire body of processes and components which create printed circuit board assemblies with lead less components.
Solder
An alloy that melts at relatively low temperatures and is used to join or seal metals with higher melting points. A metal alloy with a melting temperature below 427°C (800°F).
Solder Mask
Non-preferred term for solder resist.
Spc
Statistical Process Control. The collection of process data and creation of control charting is a tool used to monitor processes and to assure that they remain In Control or stable. Control charts help distinguish process variation due to assignable causes from those due to unassignable causes.
Step-And-Repeat
A method by which successive exposures of a single image are made to produce a multiple image production master.
Substrate
A material on whose surface adhesive substance is spread for bonding or coating. Also, any material which provides a supporting surface for other materials used to support printed circuit patterns.
Test Coupon
A portion of a printed board or of a panel containing printed coupons used to determine the acceptability of such a board.
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.
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.
Twist
A laminate defect in which deviation from planarity results in a twisted arc.
Underwriters Symbol
A logotype denoting that a product has been recognized (accepted) by Underwriters Laboratories Inc. (UL).
Uv Curing
Polymerizing, hardening, or cross linking a low molecular weight resinous material in a wet coating ink using ultra violet light as an energy source.
Via
A plated through hole that is used as an inter-layer connection, but doesn’t have component lead or other reinforcing material inserted in it.
Void
The absence of any substances in a localized area.
Wave Soldering
A process wherein assembled printed boards are brought in contact with a continuously flowing and circulating mass of solder.
Wicking
Migration of copper salts into the glass fibers of the insulating material.