Index:

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

A

Activating - A treatment that renders nonconductive material receptive to electroless deposition. Nonpreferred synonyms: Seeding, Catalyzing, and Sensitizing.

Annular Ring - The conductive foil and plating surrounding a hole.

Artwork - An accurately-scaled ( usually 1:1 ) pattern which is used to produce the artwork master or production master.

Artwork Generation - The Process of transferring the idea for a circuit pattern into a precision, reproducible artwork master for mass production manufacturing. Generation can be executed by the traditional manual drafting and photographic technique or via CAD techniques.

Artwork Master - The photographic film or plate which embodies the image of the PWB pattern, usually on a 1:1 scale. It is commonly a sensitized gelatin plate, but for high precision work, a chromium plate can be used.

Aspect Ratio - The ratio of the circuit board thickness to the smallest hole diameter.

Assembly - A number of parts or subassemblies, thereof, or any combination thereof joined together to perform a specific function.

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B

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

Backplanes and Panels - Interconnection panels into or onto which printed circuits, other panels, or integrated circuit packages can be plugged or mounted.

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

Base Copper - The thin copper foil portion of a copperclad laminate for PWBs. It can be present on one or both sides of the board.

Base Laminate (Base Material)- The substrate material upon which the conductive pattern may be formed. The base material may be rigid flexi-rigid, or flexible.

Base Laminate Thickness (Material) - The thickness of the base material excluding metal foil or material deposited on the surface.

Base Dimension - A numerical value used to describe the theoretical exact location of a feature or hole. It is the basis from which permissible variations are established by tolerances on other dimensions, in notes, or by feature control systems.

"Bed-of-Nails" Technique - A method of testing printed circuit boards that employs a test fixture mounting an array of contact pins configured so as to engage plated-through holes on the board.

Beveling Machines - Equipment that puts 90 degree edges or 15 degree, 30, 45, or 60 degree bevels on printed wire boards. Well designed beveling machines collect dust or shavings in order to maintain high plant environment standards.

Bleeding - A condition in which a plated hole discharges process material or solution from crevices or voids.

Blind Via - A Via extending to only one surface of a printed circuit board. See also: Buried Via.

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.

Blow Hole - A void caused by outgassing. (Outgassing is a gaseous emission from a printed circuit assembly when exposed to a reduced pressure or heat or both.

Bond Strength - The force per unit area required to separate two adjacent layers of a board by a force perpendicular to the board surface. See peel Strength.

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.

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

Bridging, Electrical - The formation of a conductive path between two insulated conductors such as adjacent foil traces on a circuit board.

Buried Via - A Via not extending to the surface of the printed circuit board.

Bus Bars - Power distribution components. Many consist of two or more conductor layers, electrically insulated from one another and from other components by thin direct layers. Applications include distribution of power on PC boards.

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C

Card - Nonpreferred term for a printed board.

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

Center-To-Center Spacing - The normal distance between the centers of adjacent features or traces on any layer of a printed circuit board.

Chamfer - A corner which has been rounded 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. In printed wiring its value depends on the width and thickness of the conductor, the distance from the conductor to ground plane(s), and the dielectric constant of the insulating media.

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

Circuit- The interconnection of a number of devices in one or more closed paths to perform a desired electrical or electronic function.

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.

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

Coefficient of Expansion, Thermal - The fractional change in dimension of a material for a unit change in temperature.

Component Hole - A hole used for the attachment and electrical connection of component terminations, including pins and wires, to the printed circuit board.

Component Side - That side of the printed circuit board on which most of the components will be mounted.

Conductive Foil - A thin sheet of metal that may cover one or both sides of the base material and is intended for forming 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 thin conductive area on a PWB surface or internal layer usually composed of lands (to which component leads are connected) and paths

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-To-Hole Spacing - The distance between the edge of a conductor and the edge of a supported or unsupported hole.

Conductor Thickness - The thickness of the conductor including all metallic coatings.

Conductor Width - The observable width of the pertinent conductor at any point chosen at random on the printed circuit board.

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

Cooridnate Tolerancing - A method of tolerancing hole locations in which the tolerance is applied directly to linear and angular dimensions, usually forming a rectangular area of allowable variation. Also see: Positional Limitation Tolerancing and True Position Tolerancing.

Copper Clad - A material which includes a base material and one or two thin sheets of copper bonded to one or both of its sides.

Copper Foil - A cathode-quality electrolytic copper used as a conductor for printed circuits. It is made in a number of weights (thicknesses); the traditional weights are 1 and 2 ounces per square foot (0.0014 and 0.0028 inch thick ).

Cosmetic Defect - A defect such as a slight change in its usual color, that doesn't affect functionality of the board.

Cover Lay, Cover Layer, Cover Coat - Outer layer(s) of insulating material applied over the conductive pattern on the surface of a printed circuit board.

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 fibers in the glass cloth and connecting weave intersections.

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.

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D

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

Deburring - Process of removing a burr after board drilling. Deburring operations fall into two categories; producing a clean, sharp edge when removing heavy burr; and radiusing the edge of the holes to prevent build-up in plating.

Defect - Any deviation from the normally accepted characteristics of a product or component. Also see: Major Defect and Minor Defect.

Delamination - A separation between any of the layers of a base material or between the laminate and the conductive foil, or both.

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

Dewetting - A condition which occurs when molten solder has coated a surface and then recedes, leaving irregularly shaped globules of solder separated by areas covered with a thin solder film; base metal is not exposed.

Dielectric - An insulating medium which occupies the region between two conductors.

Digitizing - Any method of reducing feature locations on a flat plane to digital representation in X - Y coordinates.

Dimensional Stability - A measure of dimensional change caused by factors such as temperature, humidity, chemical treatment, age, or stress; usually expressed as units/unit.

Dimensioned Hole - A hole in a printed circuit board where the means of determining location is by coordinate values not necessarily coinciding with the stated grid.

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

Drilling Machines - Equipment used in printed wire board drilling operations. The two basic types are:

Manual Machines: Positioned by a template, they can be single spindle or multiple spindle and are usually limited to four spindles capable of satisfying the prototype and short run segment of the printed wire board market. They average 35 to 45 "hits" (drilled holes) per minute with accuracy's in the range of 0.011 inch to 0.003 inch of the template position.

Numerically Controlled Machines: capable of 200 plus "hits" (drilled holes) per minute with table positions and repeatabilities of 0.002 inch to 0.005 inch. They are designed for high production and extreme accuracies and are more versatile than manual machines.

Drills, Circuit Board - Solid, carbide cutting tools with four facet points and two helical flutes designed specifically for the fast removal of chips in extremely abrasive, glass-epoxy materials.

Dry-Film Resists - Coating material in the form of laminated photosensitive sheets specifically designed for use in the manufacture of printed wire boards and chemically machined parts. They are resistant to various electroplating and etching processes.

Dry Film Solder Mask - Coating material (dry film resist) applied to the printed wire board via a lamination process to protect the board from solder or plating.

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E

Edge-Board Connector - A connector designed specifically for making removable and reliable interconnection between the edge board contacts on the edge of a printed board and external wiring.

Edge Dip Solderability Test - A solderability test performed by taking a specially-prepared specimen, fluxing it with a nonactivated resin flux, and then immersing it into a plot of molten solder at a pre-determined rate of immersion for a pre-determined dwell time, and then withdrawing it at a pre-determined rate.

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

Electroless Copper - A thin layer of copper deposited on the plastic or metallic surface of a PWB by means of a chemical reducing agent present in the deposition process (without the means of electrical current)

Electroless Deposition - The deposition of conductive material from an autocatalytic reduction of a metal ion on certain catalytic surfaces without the application of electric current

Electroplating - The electro-deposition of a 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. Ions of the metal provide transfer to metal as they make up the current flow between the electrodes.

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

Epoxy Smear - Epoxy resin which has been deposited onto the surface or edges of the conductive pattern during drilling. Also called Resin Smear or Epoxy .Resins.

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

Etchback - The controlled removal of all components of base material by a chemical process on the side wall of holes in order to expose additional 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 - The process of removing unwanted metallic substance (bonded to a base ) via chemical; or chemical and electrolytic means.

Etching Resists - Materials deposited on the surface of a copper-clad base material that prevent the removal by etching of the conductive areas they cover.

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F

Fingers - Nonpreferred term for edge-board contacts.

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 manufacturing a product that will meet specified requirements.

Fixture - A device that enables interfacing a printed circuit board with a spring-contact probe test pattern. It contains either a dedicated head or an interface for interchangeable test heads and means of keying the product to be tested.

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

Foil - A thin sheet of metal, usually copper, used as the conductor for printed circuits. The thinner the foil, the lower the required etch time. Thinner foils also permit finer definition and spacing. See Copper Foil.

Fused Coating - A metallic coating ( usually tin or solder alloy ) which has been melted and solidified forming a metallurgical bond to the base material.

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G

Glass Transition - The temperature at which an amorphous polymer ( or the amorphous regions in a partially crystaline polymer ) changes from a hard and relatively brittle condition to a viscous or rubbery condition. When this transition occurs, many physical properties undergo significant changes. Some of those properties are hardness, brittleness, coefficient of thermal expansion, and specific heat.

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.

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H

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

Heating Sinking Plane - A continuous sheet of metal on or in a printed board that functions to dissipate heat away from heat sensitive components

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

Hole Pattern - The arrangement of all holes in a printed board
.
Hole Void - A void in the metallic deposit of a plated-through hole exposing the base material.

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I

Internal Shorts Test - A testing procedure to determine the absence of internal shorts. Voltage is supplied to a given internal ground (or power plane) and the lands are sequentially probed by the application of voltage. The current flow between the energized land and the plane under test indicates an internal short (unless this land is intended to

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 ) as measured between any pair of contacts or conductors.

Internal Layer - A conductive pattern which is contained entirely within a multilayer printed board.

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J

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

K

Keying 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.

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L

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

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

Laminate Presses, Multilayer - Equipment that applies both pressure and heat to laminate and prepreg to make multilayer boards.

Lamination - The process of preparing a laminate; also, any layer in a laminate.

Land - A portion of a conductive pattern usually, but not exclusively, used for the connection and/or attachment of components. Also called Pad, Boss, Terminal area, Blivet, Tab, Spot, or Donut.

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

Layer-To-Layer Spacing - The thickness of dielectric material between adjacent layers of conductive circuitry in a multilayer printed circuit board.

Lay-Up - The technique of registering and stacking layers of multilayer board materials ( laminate and prepreg ) in preparation for the laminating cycle.

Legend - A format of lettering or symbols on the printed board; i.e.,., part number, component locations, and patterns.

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M

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

Mask - A material applied to enable selective etching, plating, or the application of solder to a printed circuit board.

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.

Measling - A condition existing in the base laminate in the form of discrete white spots or "crosses" below the surface of the base laminate, reflecting a separation of fibers in the glass cloth at the weave intersection.

Microsectioning - The preparation of a specimen for the microscopic examination of the material to be examined, usually by cutting out a cross-section, followed by encapsulation, polishing, etching, staining, etc.

Mil - One-thousandth ( 0.001 ) of an inch.

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 multilayer printed circuit boards and to the edge of the plating on outside layers of multilayer boards and double-sided boards.

Minimum Electrical Spacing - The minimum allowable distance between adjacent conductors that is sufficient to prevent dielectric breakdown, corona or both, between the conductors at any given voltage and altitude.

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

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 standards 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 patterns.

Multilayer Printed Wire Boards - Printed circuit boards consisting of three or more conducting circuit planes separated by insulating material and bonded together with internal and external connections to each level of the circuitry as required.

Multilayer Printed Board Sequentially Laminated - A multilayer board which is formed by laminating through hole plated double-sided or multilayer boards together.

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N

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

Negative - An 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.

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

O

Outgassing - De-aeration or other gaseous emission from a printed circuit board when exposed to a reduced pressure, or heat, or both.

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

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P

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

Panel - 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 Back-planes and Panels.

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

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 - Selective plating of a conductive pattern.

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

Photoplotter - A high accuracy (0.002 inch or better ) flatbed plotter with a programmable, photo image projector assembly. It is most often used to produce actual size master patterns for printed circuit artwork directly on dimensionally-stable, high-contrast photographic film.

Pinhole - A minute hole through a layer or pattern.

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

Plated-Through Hole - A hole with the deposition of metal ( usually copper ) on its sides to provide electrical connections between conductive patterns at the levels of a printed circuit board.

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

Plating, Electroless - A method of metal deposition employing a chemical reducing agent present in the processing solution. The process is further characterized by the catalytic nature of the surface which enables the metal to be plated to any thickness.

Plating, Electrolytic - A method of metal deposition employing the work or cathode; the anode; the electrolyte, a solution containing dissolved salts of the metal to be plated; and a source of direct current ( See Electroplating ).

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 photo-polymer resists.

Plating Up - The process consisting of the electrochemical deposition of a conductive material on the base material after the base material has been made conductive.

Plating Void - The absence of a plating metal from a specified plating area.

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

Polyimide Resins - High temperature thermoplastics used with glass to produce printed circuit laminates for multilayer and other circuit applications requiring high temperature performance.

Positional Lamination Tolerancing - Defines a zone within which the axis or center plane of a feature is permitted to vary from true ( theoretically exact ) position.

Positive - An artwork master or production master in which the intended conductive patterns is opaque to light, and the areas intended to be free from conductive material are transparent.

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

Press-Fit Contact - An electrical contact which can be pressed into a hole in an insulator, printed board ( with or without plated-through holes ), or a metal plate.

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

Production Master - A 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. (a) Single-Imaged Production Master - A production master used in the process of making a single printed circuit board. (b) Multiple-Imaged Production Master - A production master used in the process of making two or more printed circuit boards simultaneously.

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R

Reflowing - The melting of an electro-deposit followed by solidification. The surface has the appearance and physical characteristics of being hot-dipped.

Registration - The degree of conformity of the position of a pattern, or a portion thereof, with its intended position or with that of any other conductor layer of a board.

Resin - an inorganic substance of natural or synthetic origin which is polymeric in structure and predominantly amorphous

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

Resin Starved Area - A region in a printed circuit board that has an insufficient amount of resin to wet out the reinforcement completely, evidenced by low gloss, dry spots or exposed fibers.

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 resist pattern on a printed circuit board enabling the exposure of conductive areas for subsequent plating.

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S

Screen - Surface on which the master artwork of the circuit pattern is projected. Screen fabrics include polyester, stainless steel, nylon and silk.

Screen Printing - A process for transferring an image to a surface by forcing suitable media through a stencil screen with a squeege. Also called Silk Screening.

Shadowing - A condition occurring during etchback in which the dielectric material, in intimate contact with the foil, is incompletely removed although acceptable etchback may have been achieved elsewhere.

Silk Screening - See Screen Printing.

Single-Sided Board - A printed board with conductive pattern on one side only.

Solder - An alloy that melts at relatively low temperatures and which is used to join or seal metals with higher melting points. Solder alloys melt over a range of temperatures; the temperature at which a solder begins to melt is the solidus, and the temperature at which it is completely molten is the liquidus.

Solder Leveling - The process of dipping printed circuit boards into hot liquids, or exposing them to liquid waves to achieve fusion.

Solder Mask Coating - Non-preferred term for Resist.

Solder Resists - Coatings which mask and insulate portions of a circuit pattern where solder is not desired.

Solderability Testing - The evaluation of a metal to determine its ability to be wetted by solder. Such evaluations include; the edge dip solderability test; the meniscus test; and the globule test.

Starvation, Resin - A deficiency of resin in base material which is apparent after lamination by the presence of weave texture, low gloss, or dry spots.

Step-And-Repeat - A method by which successive exposures of a singe image are made to produce a Multiple-Image Production Master.

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

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T

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

Test Coupon - A portion of a printed circuit board or of a panel containing printed circuit coupons, used to determine the acceptability of such boards.

Thin Foil - A metal sheet less than 0.0007 inches ( oz ) thick.

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

Tooling Holes - The general term for holes placed on a printed circuit board, or a panel, for registration and hold-down purposes during the manufacturing process.

True Position - The theoretically exact location of a feature or hole established by basic dimension.

True Position Tolerancing - A method of tolerancing hole locations. The tolerance is expressed as a radius or diameter of allowable variation from the "true position" center defined by a dimension or grid coordinate. Also see: Coordinate Tolerancing and Positional Limitation Tolerancing.

Twist - The deformation of a rectangular sheet such as that one of the corners is not in the plane containing the other three corners.

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U

UV ( Ultraviolet ) Curing - Polymerizing, hardening, or cross linking a low molecular weight resinous material in a wet coating or ink, using ultraviolet light as an energy source.

Ultrasonic Cleaning Equipment - Equipment used for ultrasonic immersion cleaning employing a transducer which converts electrical energy into mechanical energy; an ultrasonic generator, and a tank to contain the cleaning liquid. Both automated and conveyorized ultrasonic cleaning systems exist.

Undercut - The reduction of conductor cross-section on a printed circuit board caused by etchant removal of conductive metal under the edge of the resist.

V

Via Hole - A plated-through hole used as a through connection, but in which there is not intention to insert a component lead or other reinforcing material.

Void - The absence of substance in a localized region.

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W

Warp - Non-preferred term for Bow.

Weave Exposure - A surface condition of base material in which the unbroken fibers of woven glass cloth are not completely covered by resin.

Weave Texture - A surface condition of base material in which a weave pattern of glass cloth is apparent although the unbroken fibers 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 slender acicular (needle-shaped ) metallic growth on a printed circuit board.

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