Here is a detailed glossary of all the relevant words to Pica Manufacturing. 

Provided by Bob Tarzwell & Dan Beaulieu

PCB Glossary of Important Terms


A chemical treatment that allows nonconductive laminate to accept electroless. Also called, catalyzing, seeding and sensitizing.

Additive Process

A process in printed circuit board manufacturing where the circuit pattern is produced by the addition of metal rather than etching metal away.

Air Gap

A routed space between two traces to control creepage.


A chemical that has a PH above 7.

American Wire Gage (AWG)

A method of specifying wire diameter. The higher the number, the smaller the diameter.

Analytical Services Lab

Performs various tests such as plating thickness, inner layer connections to hole walls, photos or x-rays of circuit boards when required.

Annular Ring

Copper material around a hole which creates a pad.


The positive element used in the plating tank. The power supply is connected to the positive potential. The anodes are used to supply and accelerate the metal ion towards the panel being plated.


An indexed shape with a specified X and Y dimension, or line-type with a specified width, used as a basic element or object by a photo plotter in plotting geometric patterns on film. The index of the aperture is its D code. A line of textual data in an aperture list describing the D code and position, the shape, flash or draw and the X and Y dimensions of an aperture. See Gerber.

Aperture List

An ASCII text data file, which describes the size and shape of the D codes. See Gerber.


A group of circuits arranged in a pattern.


A photo plotted film 1:1 pattern, which is used to produce the Diazo production master.


American Standard Code for Information Interchange: It is the character sets used in almost all present-day computers. US-ASCII uses only the lower seven bits (character points 0 to 127) to convey some control codes, space, numbers, most basic punctuation, and unaccented letters a-z and A-Z.

Aspect Ratio

The ratio of the circuit board thickness to the smallest drilled hole diameter.

Assembly Drawing

A drawing showing the locations of components, with their reference designators, on a printed circuit. Also called component locator drawing.


A drawing software standard which is used by RF and silicon chip packaging designers, saved in a DFX format to convert to Gerber for PCB manufacturing.

Automatic Optical Inspection (AOI)

Computerized inspection of circuit boards to find shorts and opens.

Automated Test Equipment (ATE)

Equipment that automatically tests and analyzes electrical parameters to evaluate quality of the PCB.


Automatic router, a computer program that designs or routes the traces in a design automatically.

Axial Leads

Leads coming out of the ends and along the axis of a resistor, capacitor, or other axial part, rather than out the side.

B-Stage Material

Sheet material (fiberglass cloth) impregnated with a resin cured to an intermediate stage (B- stage resin). Pre-preg is the preferred term.

Back Planes

Interconnection panels onto which printed circuits, other panels, or integrated circuit packages can be plugged or mounted. Typical thickness is 0.125″- 0.300″.

Backup Material

A .093 mil thick layer of Phenolic, paper or wood by products, to protect the drill plate and prevent exit burrs.

Ball Grid Array (BGA)

A leadless chip package in which the external terminals form a grid-style array with solder balls which carry the electrical connection to the outside of the package. The PCB design will have round landing pads to which the solder balls are soldered when the PCB is heated in a reflow oven.

Bare Board

An unpopulated PCB with no components assembled on it yet.


The wall formed by plating a drilled hole.

Base Copper

Copper foil provided in sheet form to clad one or both sides of a piece of laminate used as either internal or external layers.

Base Laminate

The dielectric material upon which the conductive pattern may be formed. The base material may be rigid or flexible.

Base Material

See Base Laminate.


A method of testing printed circuit boards that employs a test figure mounting an array of contact pins configured to engage plated thru- holes on the board.


An angled edge of a printed circuit board for gold fingers.

Bill of Materials (BOM)

Pronounced “bomb”. A list of components of the assembly such as a printed circuit board. For a PCB, the BOM must include reference designators for the components used and descriptions which uniquely identify each component. A BOM is used for ordering parts, along with an assembly drawing.


A situation where a plated hole emits electroless solution from crevices or voids. Also, the edge of a silkscreen ink line blotting or bleeding outward past the desired edge.

Blind Via Hole

A plated-through hole connecting an outer layer to one or more internal conductor layers of a multilayer printed board but not extending fully through all of the layers of base material.


An area of swelling and separation or delamination between any of the layers of a laminated base material or between base material and copper foil.

Blow Hole

An area of swelling and separation or delamination between any of the layers of a laminated base material or between base material and copper foil.

Board House, Vendor

A manufacturer of printed circuit boards.

Bond Strength

The force in pounds per square inches required to delaminate two adjacent layers of a board when attempting to separate the layers. See Peel Strength.


The measurement of flatness of a circuit board between corners and the center.


A PCB panel format with board units connected to a panel by number of tabs around the units. Units break-away from panel after assembly. Panel profiling of this format may be routed or punched.

Breakdown Voltage

The voltage at which an insulator or dielectric ruptures or at which ionization and conduction take place and creates an arc.


Poor registration between the drilled hole and the pad on a printed circuit board to the extent that the outer edge of the hole is not within the area of the pad.

Bridging, Electrical

The formation of a conductive path between two insulated conductors such as adjacent traces on a circuit board.


The blending of bismaleimide/triazine and epoxy resin provides enhanced thermal, mechanical and electrical performance over standard epoxy systems.


Team meeting to review customer designs against manufacturing process capabilities. Used to identify possible failure modes prior to fabrication.

Buried vias

Vias which start and end in the middle of the board.


A ridge left on the surface copper after drilling.


A heavy trace or conductive metal strip on the printed circuit board used to distribute voltage and grounds.

Bypass Capacitor

A capacitor used for providing a low impedance A/C path around a circuit element.


The condition of a resin polymer when it is in the fully cured, cross-linked solid state, with high molecular weight.


The property of a series of parallel conductors between a dielectric to store electrical signals when a potential difference exists between them.


An older name for a printed circuit board.

Card-edge Connector

The nominal distance between the centers of adjacent features or traces on any layer of a printed circuit board. Also known as “pitch.”

Ceramic Ball Grid Array (CBGA)

A ball grid array package with a ceramic substrate.


A corner that has been rounded to eliminate an otherwise sharp edge.

Characteristic Impedance

A compound measurement of the resistance, inductance, conductance and capacitance of a transmission line expressed in ohms. In printed circuits, 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.


The aluminum frame used in silk screening inks onto the board.

Check Plots

Photo 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 transparency of multiple layers or may be a plot of holes only for missing drill hole checking.


An integrated circuit manufactured on a semiconductor substrate and then cut or etched away from the silicon wafer.

Chip-on-board (COB)

Integrated circuits or bare die are glued and wire-bonded directly to printed circuit boards instead of first being packaged and then glob topped. It can be identified by the black glob of plastic covering the chip on the board.

Chip Scale Package

A chip package in which the total package size is no more than 20% greater than the size of the die within, e.g. micro BGA.

Circuitry Layer

The layer of a PCB containing copper conductors, including signal, ground and voltage planes.

Clad or Cladding

A thin layer or sheet of copper foil, which is bonded to a composite laminate core to create the base material for printed circuits. See Base Copper.

Clean Room

A room with very low specified limits of concentration of air born particles. It is controlled to lessen the effect of dust on imaging.

Clearance Hole

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


Complementary metal-oxide semiconductor

CNC Drill File

Programs in Exelon format which a CNC drill machine use to drill the holes in the panel.

Coefficient of Thermal Expansion (CTE)

Thermal fractional change in dimension of a material for a unit change in temperature, expressed as ppm or percentage.

Component Hole

A through hole for the attachment and electrical connection (soldering) of component terminations, including terminals and wires, to the printed circuit board.

Component Side

That side of the printed circuit board on which the majority of the components will be mounted.

Computer Aided Design (CAD)

A software program that calculates impedance modeling and provides graphical creation of a printed circuit board conductor layout and signal routes.


Simply a combination of the two terms CAD and CAM. A term used to name the work done to the PCB data.

Computer Aided Manufacturing (CAM)

The use of computers to crate tooling data and transfer the electronic design (CAD) to the manufacturing machines.

CAM Files

The data files used directly in the manufacture of printed circuits. One type of CAM files is a Gerber file, which controls a photo plotter, drill or LDI exposure unit.

Computer Assisted Engineering (CAE)

In electronics work, CAE refers to schematic software packages.

Conductive Anodic Filament (CAF)

An electrical short which occurs inside or outside the PCB when a conductive filament forms between two adjacent conductors under a DC electrical bias and humidity.

Conductive Pattern

The configuration or design of the conductive material on the base laminate through which electrical energy passes. It includes conductors, lands, and through connections.


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

Conductor Base Width

The conductor width at the plane of the surface of the base material. See Conductor Width.

Conductor Thickness

The total thickness of the trace or land including all metallic coatings.

Conductor-to-Hole Spacing

The distance between the edge of a conductor and the edge of hole.

Conductor Width

The observable width of the pertinent conductor on the printed circuit board.

Conformal Coating

An insulated protective coating that conforms to the components and is applied on the completed board assembly.


An impurity or foreign substance whose presence on printed wiring assemblies which could electrically, chemically, or galvanically corrode the system.


An uninterrupted flow of electrical current in a circuit.

Controlled Impedance

The matching of substrate material Dk with trace dimensions and locations to create specified electric impedance as required by the designers.

Contract Manufacturing

The manufacturing of products or subcomponents of products to be sold under a different company’s name.

Cool Down

The period in the reflow process after peak temperature when the temperature drops to the point where the solder joints fuse or solidify.

Coordinate Tolerance

A method of qualifying hole locations in which the variance is applied directly to linear and angular dimensions, usually forming a rectangular area of allowable variation.

Copper Foil

See Base Copper and Clad or Cladding.

Copper Pouring or Copper Hatch

CAD/CAM terms. Refers to filling of an enclosed area (generally defined by polygon lines) with a solid or hatch pattern to create a copper plane or a section of copper plane.

Copper Thickness and Copper Plating

Copper thickness usually specified in terms of number of oz/sq ft. 1/2 oz: 17.5um or 0.0007″/sq. ft; 1 oz: 35 um or 0.0014″/sq. ft. The thickness of copper specified will be the final thickness of base material plus copper plating thickness. Generally base material comes with 1/4, 1/2, 1, and 2 oz. but finish copper thickness ranges from 1/2 to 6 oz.


The copper foil laminated fiberglass panel that printed circuit boards are built upon. Also known as substrate panel or interlayer.

Core Group

Daily operational meeting to ensure producing and delivering high quality, cost-effective circuit boards on time.

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.

Cosmetic Defect

A defect such as a slight change in its usual color that doesn’t affect a board’s functionality.


See test coupon

Cover Lay or Cover Coat

Outer layer(s) of insulating material applied over the conductive pattern on the surface of a printed circuit board.


Central Processor Unit.


A condition existing in the base material 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 resin material.


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

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 Outs

Removal of an internal area of the board.

D code

A datum in a Gerber file which acts as a command to a photo plotter. D code in a Gerber file takes the form of a number prefixed by the letter. E.g.”D20″.

Data Exchange Format (DXF)

Commonly used in mechanical CAD systems.

Datum Reference

A defined point, line, or plane used to locate the pattern or layer for manufacturing inspection.


Process of removing burrs of base copper material that remain around holes after board drilling.


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


The accuracy of pattern edges in a printed circuit relative to the master pattern.


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

Design Rule Check (DRC)

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


Removal of epoxy smear (melted resin) and drilling debris from a drilled hole wall.

Destructive Testing

Sectioning a portion of printed circuit panel and examining the sections with a microscope. This is performed on coupons, not the functional part of the PCB.


An imaging operation in which unpolymerized (unexposed) photo-resist is dissolved or washed away to produce a copper board with a photo- resist pattern for etching or plating.


A condition that occurs when molten solder has failed to properly coat a metal surface and then recedes, leaving irregularly shaped globules of solder separated by areas covered with a thin solder film; base metal is not usually exposed.


Dicyandiamide, common cross-linking agent used in FR4 construction.


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

Die Bonder

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


An insulating medium, which occupies the region between two or more conductors and prevents electrical shorts.

Dielectric Constant (Dk)

The ratio of permittivity of the material to that of a vacuum (referred to as relative permittivity).

Dielectric Strength

A measurement of the voltage required to create an arc inside the dielectric.

Differential Signal

A method of high speed signal transmission through two wires, which always has opposite states. The signal data is the polarity difference between the wires.


A computerized method of converting feature locations on a flat plane to digital X-Y coordinates.

Dimensional Stability

A measure of dimensional change caused by factors such as temperature, humidity, chemical treatment, age or stress.

Dimensioned Hole

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


Dual in line package of silicon chip.

Discrete Component

A component that has been fabricated prior to its installation of resistors, capacitors, diodes and transistors.


A supplier quality management practice that allows a component or product to enter.

Double-Sided Board

A circuit board with conductive copper patterns on both sides with through connected vias.


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 materials.

Drill File

A computerized file containing tool and coordinate information for drilling. Common format accepted are: EIA or Excellon in either binary or ASCII text file.

Dry Film

A photo imagable material, which is laminated onto a bare copper panel. It is exposed with 365 nm UV light through a negative photo tool. The exposed dry film is hardened by the UV light.


Double-treated foil.


Electro deposited

Edge Bevel

A bevel operation performed on edge connectors to improve their wear and ease of installation.

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 Clearance

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

Edge Connector

A connector on the circuit board edge of gold-plated traces used to connect to other circuit boards or electronic devices.

Edge Dip Solderability

A solderability test performed by taking a prepared specimen, fluxing it and then immersing it into a pot of molten solder for 10 seconds dwell time, and then withdrawing it.

Electroless Plating/Electroless Deposition

The deposition of metal from an auto-catalytic plating solution without application of electrical current. Short for “electroless.” This process is required to plate the nonconductive hole walls in order that they may be subsequently electroplated. Also called “PTH.”


The electro deposition of a metal coating on a PCB. The board is placed in an electrolyte and connected to one terminal of a DC voltage source. The metal to be deposited is 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.


Resisters, capacitors and small chip die are placed inside the PCB to increase density.


Electroless nickel, immersion gold final finish


The damaging addition and trapping of air, flux, and/or fumes within solder mask or laminate. It is caused by contamination or improper plating.

Entry Material

A thin layer of composite material or aluminum foil or paper products that is placed on top of the boards to be drilled to improve drill accuracy and prevent burrs and dents.

Epoxy Smear

Epoxy resin that has been deposited onto the surface or edges of the conductive inner layer pattern during drilling. Also called Resin Smear.


Electrostatic discharge


Chemical removal of copper to achieve a circuit pattern.

Etch Back

The controlled removal of the glass fibers and epoxy of the base material by a strong chemical process on the sidewall of holes to expose additional internal conductor copper.

Etch Factor

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


Short for fabrication.

Fabrication Drawing

A drawing used to guide construction of a printed board. It shows all of the different sizes of holes to be drilled, tolerances, dimensions of the board edges and notes on the materials to be used. Called “fab drawing” for short.


Etched features or drilled hole used for optical alignment during assembly operations.

Film Artwork

A positive or negative piece of film containing a circuit, solder mask, or nomenclature pattern.

Fine Line Design

Printed circuit design permitting two to three traces between adjacent chip pins. Typically, 2 mil line, 2 mil space is considered fine line.

Fine Pitch

Refers to chip packages with lead pitches below 0.050″. The largest pitch in this class of parts is 0.8 mm, or about 0.031″. Lead pitches as small as 0.2 mm (0.008″) are used.


A gold-plated terminal of a card-edge connector.

First Article

A sample part or test board manufactured prior to the start of production to assure that the vendor is capable of producing a circuit that will meet specified requirements.


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


A standard size sheet of laminate material, which is processed into one or more circuit boards. Also called panel.

Flex Circuit

Flexible circuit, a printed circuit made of thin, flexible material.


A mounting approach in which the chip is inverted and connected directly to the substrate rather than using the more common wire bonding technique.


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

Flying Probe Tester

An electrical testing machine that uses multiple moving arms to make contact with two spots on the copper circuitry and send an electrical signal between them. A procedure that determines if a short or open exists.


A low-grade version of FR2. Tg 130°C.


A grade of flame retardant industrial laminate having a substrate of paper and a resin binder of Phenolic. It is used for PCB laminate and cheaper than the woven glass fabrics. Tg 105°C.


A grade of flame retardant industrial laminate having a substrate of woven-glass fabric and resin binder of epoxy. FR4 is the most common dielectric material used in the construction of PCBs. Its dielectric constant is from 4.4 to 5.2 at below-microwave frequencies. As frequency climbs over 1 GHz, the dielectric constant of FR4 gradually drops. Tg 150°C to 175°C.


Fire retardant glass and polyester substrate material for electronic circuits. Inexpensive and popular for automobile electronics.


A multi-functional epoxy system that is a standard multilayer material.


A multi-functional epoxy laminate and prepreg that has a Tg of 170°C. It is used in applications where a higher temperature material is needed.


A high-performance FR4 epoxy laminate and prepreg that has a Tg of 180°C. The low dielectric constant is ideal for faster signal speed and improved signal integrity.

Fused Coating

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


General purpose epoxy/fiberglass woven fabric PCB material. This has been replaced by a high-grade material such as FR4.

Gerber File

Data file used to control a photo plotter, named after Gerber Scientific Co., who manufactured the original vector photo plotter.

GIL Grade MC3D

A composite laminate comprised of woven glass sheets on both sides of a glass paper core. MC3D exhibits excellent electrical properties with a low and stable Dk and Df.

Glass Transition Temperature (Tg)

The temperature at which a 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.

Gold/Nickel plating

Used for contact fingers. Common specifications for this plating are: 0.000020″ gold over 0.000250″ nickel.


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

Ground Plane

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


Mechanically induced fracturing delimitation on or below the surface of the base material. It is usually exhibited by a light area around holes or other machines areas, or both.

Heavy Copper PCB

Circuit boards with more than 4 oz. of copper and up to 20 oz. of copper for power circuits.

Hermetic Sealing

Airtight sealing of an object.

High Density Interconnect (HDI)

Very fine lines and thin dielectrics, made with sequential lamination.

Hole Breakout

A hole which is not completely surrounded by the land.

Hole Density

The quantity of holes in a PCB per unit area.

Hole Void

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

Hole Wall

The vertical surface of a drilled hole of a printed circuit board.

Hot Air Solder Leveling (HASL)

A method of coating exposed copper with solder by inserting a panel at 45 degrees into a bath of molten solder, then passing the panel rapidly past a series of hot air jets to remove excess solder.

HPGL Format

HPGL is a Hewlett Packard pen-plot format file generated from almost all CAD systems.


That portion on artwork masters, working tools, silk screens, or photo masks that would be considered the photographic image. Also would include images created with photo-resists or silk-screening techniques. Generally, “one image” refers to a single circuit board image; thus there may be several images per flat.


A capacitive opposition to the flow of AC electrical current. This term is used to describe how high frequency circuit boards will react.


Common term for screen resist.

Inner Layer

Any layer that will be laminated into the inside of a multilayer board.

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 as measured between any pair of contacts or conductors.


The Institute for Interconnecting and Packaging Electronic Circuits.


A PCB wide industry quality standard for acceptance of PCBs.


A CAD/CAM data exchange format developed by IPC. for use of photo plotting, electrical testing and other CAM functions.


Infrared radiation


International Standards Organization; i.e. ISO9000.

Jumper Wire

An electrical connection formed by wire between two points on a printed board, added after the circuit is etched.


A system for producing the right items, at the right time, in the right amounts, for customers.


A widening of the rout path which allows extra space for hardware to be attached to the board.

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.


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

Laminate Thickness

Thickness of the base material, not including metal-clad, prior to any processing. Applies to single or double-sided material.

Laminate Void

Lack of laminate material or epoxy in an area that normally should contain laminate material.

Laminating Presses

Multilayer equipment that applies both pressure and heat to laminate and pre-preg to make multilayer boards.


The process of pressing a laminate in a hot high pressure hydraulic press.


A portion of a copper conductive usually, but not exclusively, used for the connection and/or attachment of components. Also called pad.

Landless Hole

A plated-through hole without land(s). Also referred to as padless plated holes.

Laser Photo Plotter

A photo plotter which uses a laser on a X-Y computerized table to expose film to create the image.

Layer-to-Layer Spacing

The thickness of dielectric material between adjacent layers or conductive circuitry in a multilayer printed circuit board.


(1) The technique of registering and stacking layers of materials (laminate and pre-preg) for a multilayer board in preparation for the laminating cycle. (2) The laying out of repeat images on film to create multiple groups of circuit boards.


Laser Direct Imaging of dry film.


A terminal on a component used to solder to the board.

Lead Time

The time a customer must wait to receive a product after placing an order.

Leakage Current

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


Silkscreen printed letters or symbols on the PCB, such as part numbers and product, typically in white.

Major Defect

A defect that could result in a failure or significantly reduces the usability of the circuit for its designed purpose.


A term defining the ability of a board design to meet manufacturing requirements.

Manufacturing and Technology Roadmap

A strategic outline of what manufacturing and technology methods, machines and process will be used.


A material applied to create selective etching, plating, or the application of solder or solder mask to a printed circuit board.


Multi-Chip Module.


Condition existing in the base laminate in the form of discrete white spots or “crosses” below the surface of the base laminate, indicating a separation of fibers in the glass cloth at the weave intersection.

Metal Foil

The thin sheets or rolls of conductive material of a printed circuit board from which circuits are formed. Metal foil is generally copper.

Metallurgical Laboratory (Met Lab)

The process of inspecting internal board quality characteristics through the use of micro sections.

Micro BGA

Micro Ball Grid Array

Micro Circuits

Very fine lines, 2 mil and less, and small micro vias 3 mil and less.


The chemical process of removing a thin layer of copper from the copper surface of an inner layer or outer layer panel, leaving a rough surface topography.


A unit of measurement in millionths of an inch. A common unit of measurement in the printed circuit board industry.

Micro Sectioning

The creation of a specimen for the microscopic examination of the material to be examined, usually by cutting out a cross section, followed by encapsulation, polishing, ammonia etching, and staining.

Micro Via

A via used to make connection between two adjacent layers, typically less than 6 mils in diameter. May be formed by laser ablation, plasma etching, or photo processing.


One-thousandth of an inch 0.001″ (0.0254 mm); abbreviation of millionth of an inch.


A military grade quality standard for acceptance of PCBs.


A military grade quality standard for the design layout of PCBs.

Minimum Annular Ring

The minimum metal width, at the narrowest point on a pad between the edge of the drilled hole and the edge of the pad.

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, corona, or both, between the conductors at any given voltage environmental condition and altitude.

Minor Defect

A defect that is not likely to reduce the usability of the circuit for its intended design. It may be a departure from established standards having no significant bearing to the operation of the circuit.


The lack of dimensional conformity between successively produced features or patterns.


Also called Back Plane. A large, printed circuit board on which modules, subassemblies, or other printed circuit boards are mounted and interconnections made by means of connectors on the board.

Multilayer Circuit Board

A processed printed circuit configuration consisting of alternate layers of conductive patterns and insulating materials bonded together in more than two layers.

Nail Heading

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


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.


A collection of circuit points all of which are, or must be, connected to each other electrically.

Net List

List of names of symbols or parts and their connection points, which are logically connected in each net of a circuit. A net list can be “captured” (extracted electronically on a computer) from a properly prepared CAE schematic.


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


A set of rules to generate systematic names for chemical compounds. 

Nonfunctional Land

A land on internal or external layers not connected to the copper conductive pattern on its layer.

Non plated hole

A hole in the PCB that is drilled after plating so it is not plated.


The measure of free acid in a solution. A pH of 7 would be considered normal.


An unwanted break in the continuity of an electrical circuit which prevents current from flowing.


Organic Solderability Preservative.

Outer Layer

The top and bottom sides of a circuit board.


De-aeration or other gaseous emission from a printed circuit board when exposed to the soldering operation or to vacuum.


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


A chemical treatment to inner layers prior to lamination, for the purpose of increasing the roughness of clad copper to improve laminate bond strength.


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

Pad Stack

In CAD layout EDA systems, pad stack is a collection of pad shape and size information tables.


The square or rectangular base material containing one or more circuit patterns that passes successively through the production sequence and from which printed circuit boards are extracted, typically, 12˝ by 18˝ or 18˝ by 24˝. See back planes.

Panel Plating

The electrolytic plating of the entire surface of a panel (including holes).


To lay up more than one (usually identical) printed circuit on a panel. Individually printed circuits on a panel need a margin between them. Lay-up multiple printed circuits called modules, into a sub-panel so that the sub-panel can be assembled as a unit. The modules are then separated after assembly into individual PCB.

Passive Component

A device which does not add energy to the signal it passes, e.g., resistors, capacitors, and inductors.


The series of conductive copper and dielectric materials on a panel or printed circuit board. Also, the circuit design on related tools, drawings, and masters.

Pattern Plating

Selective electrolytic plating of a copper pattern.


Plastic Ball Grid Array

PC Board

The creation of artwork for the manufacture of bare PCBs on a computer database used to generate such artwork as data files (CAM files). Also called PCB layout.

PCB Design Service Bureau

A business engaged in PCB design as a service for others, especially electrical engineers. Also called PCB design shop.

Peel Strength

The force required to peel the conductor or foil from the base material.

Permittivity Measure

The ability of a material to store electrical energy when exposed to an electrical field.

Pick and Place

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

Photo Mask

A silver halide or Diazo image on a transparent substrate that is used to either block or pass light.

Photo Plotter

A high-accuracy (>0.001 inch) flatbed or rotary 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.


A light-sensitive material that is used to establish an image by exposure to light and chemical development.

Pilot Order

First production order going through process.


A minute hole through a layer or pattern.

Pink Ring

A colored area around via and through holes caused by oxide application.


The nominal distance between the centers of adjacent features or traces on any layer of a printed circuit board. Also known as “center-to- center spacing”.


A highly ionized gas containing an approximately equal number of positive ions and negative electrons. As a whole, it is electrically neutral, though conductive and affected by magnetic fields. It is used to clean contaminants off a PCB

Plastic Leaded Chip Carrier (PLCC)

An SMT chip package that is rectangular or square-shaped with leads on all four sides.


A flat plate of thick metal within the lamination press, in between which stacks of circuits are placed to be pressed.


Chemical or electromechanical deposition of metal on a pattern.

Plating Resists

Material that, when deposited on conductive areas, prevents the plating of the covered areas. Resists are available both as screened-on materials and as dry-film photopolymer resists.

Plating Void

The absence of a plating metal from a specified plating area.


The mechanical converting of X-Y Gerber 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.


To unite chemically two or more monomers or polymers to form a molecule with a higher molecular weight.

Positional Limitation Tolerancing

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


Pre-cleaning steps taken prior to an operation to ensure success of the operation.


Sheet material consisting of the base material impregnated with a synthetic resin, such as epoxy or Polyimide, partially cured to the B- stage (an intermediate stage). Short for pre- impregnated. See also B-stage.

Press-Fit Contact

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

Printed Circuit

A conductive pattern of printed components and circuits attached to a common base.

Printed Circuit Board (PCB)

The general term for a printed or etched circuit board. It includes single, double, or multiple layer boards, both rigid and flexible.

Printed Wiring Board

Another name for a Printed Circuit Board.

Production Master

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


Manufacturing small initial quantities, in short production runs, of an electronic product for testing.


Woven Teflon glass materials, with exceptionally well controlled electrical and mechanical properties. The dielectric constant range is 2.45 to 2.65 used for RF applications.

Pulse Plating

A method of plating that uses electrical pulses instead of a direct current.

Quality Control (QC)

A precise system of measurements to ensure the PCB meets the desired specifications. Also called Quality Assurance (QA).


Ability to produce a small amount of a product in a relatively short time, e.g., fabricating a printed circuit board in 24 hours from receipt of the design data.

Radial Lead

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


Resin coated copper.


A process to form a solder joint by providing heat to the solder paste.


The melting of an electro deposit tin lead. The surface has the appearance and physical characteristics of being hot-dipped.


The amount of conformity of the true position of a pattern with its intended position to that of any other point.


An undesirable substance remaining on a substrate after a process step.

Resin Smear

Melted epoxy 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.


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, Plating Resists and Solder Resists.


The ability of a material to resist the passage of electrical current through it.

Reverse Image

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


The ability of a material to resist the passage of electrical current through it.


Reprocessing that makes articles conform to specifications.


Radio Frequency


An exposed area generally attached to a rack used in electroplating, usually to provide a more uniform current density on plated parts. Robbers are intended to absorb the unevenly distributed current on parts, thereby assuring that the parts will receive a uniform electroplated coating.


Part of the European Union Directive 2002/95/EC1: “Restriction on the use of certain Hazardous Substances in electrical and electronic equipment”. This directive bans or severely curtails the use of lead, chromium, mercury, polybriminated biphenyls, cadmium and polybrominated diphenyl ethers in all products from automobiles to consumer electronics.


A CNC machine that removes portions of the panel to release the individual board with the desired shape and size required from the production panel.

Schematic Diagram

A drawing that shows, by means of graphic symbols, the electrical connections, components, and functions of an electronic circuit.


A machine in which grooves are cut on opposite sides of a panel to a depth that permits individual boards to be separated from the panel after the component assembly.


A cloth material (usually polyester or stainless steel for circuit boards) coated with a pattern that determines the flow and location of coatings forced through its openings.

Screen Printing

A process for transferring an image to a surface by squeezing suitable ink through a stencil screen with a squeegee. Also called Silk Screening.

Selective Plate

A process for plating unique features with a different metal than those of the remaining features. Created by imaging, exposing, and plating selected area and then repeating the process for the remainder of the board.


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

Short Circuit

An abnormal connection of relatively low resistance between two points of a circuit. The result is excess (often damaging) current between these points

Single Sided Board

Circuit board with copper conductors on only one side and no plated-through holes.

Solder Leveling

The process of dipping printed circuit boards into hot solder and leveling with hot air.

Solder Mask

An ink coating applied to a circuit board to prevent solder from flowing onto any areas where it is not desired or from bridging across closely spaced conductors.

Solder Mask Over Bare Copper (SMOBC)

A method of fabricating a printed circuit board with the final copper metallization under the solder mask with no protective metal. The non- coated areas are coated by solder resist, exposing only the component terminal areas. This eliminates tin lead under the components which will reflow causing a blemish.

Solder Masking Coating

A term for a liquid resist.

Solder Paste

A paste form of solder to be screen or ink jet printed on SMT pads during assembly prior to soldering.

Solder Resists

Coatings that mask and insulate portions of a circuit pattern where solder is not desired.

Solder Wick

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

Solderability Testing

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


The tool used in silk screening that forces the resist or ink through the mesh.

Stacked Vias

Micro vias in HDI stacked one upon each other.

Starvation Resin

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


Stencil is a copper or nickel foil screen with SMD pads etched openings used for solder paste screen printing in assembly.

Step and Repeat

A computerized method by which successive copies of a single image are laid up to produce a multiple-up filling of the panel.


The chemical removal of developed photo resist or plated metal.


See Base Material.

Subtractive Process

A process in printed circuit manufacturing where the product is built by the subtraction of an already existing metallic coating. The opposite of additive processing..

Surface Mount Technology (SMT)

Defines the entire body of the process and components that create printed circuit board assembly with leadless components.


Temperature of destruction, where the circuit loses 5% of its volume due to outgassing.


Glass transition temperature, in degree C, the point at which the material starts to become soft and plastic like. Also, the point where the Z axis starts to expand non-linearly.


A widening of the trace near the pad for strengthening the connections between pads and tracks. Typically used when the annular ring is 0.005″ or less but not needed.

Temperature Coefficient (TC)

The ratio of a quantity changes 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.

Tented Via

A via with dry film solder mask completely covering both its pad and its plated-thru hole. This completely insulates the via from foreign objects, thus protecting it against accidental shorts.

Test Coupon

A sample or test pattern normally made outside the actual board pattern that is used for testing to verify certain quality parameters without destroying the actual board.

Thermal Relief or Heat Relief

A thermal relief or heat relief is a type of pad used at a location where there is a connection to a copper plane. The purpose of using a thermal relief pad is to provide a connection while dissipating heat through the big copper plane.

Through Hole

A plated hole on a circuit board used for component pins leads. The holes are plated creating a circuit between multilayers.


See Robber.

Tooling Holes

Two specified holes on a printed circuit board used to position the board to mount components accurately.

Top Side

The component side.


A common term for the copper conductors.


A “recipe” for the manufacture of a board. It “travels” with each order from start to finish. The traveler identifies each order and gives instructions for each step in the process.

Two-Sided Board

See Double Sided Board.

Underwriters Laboratory (UL)

Certifying agency for consumer electronics. See also Underwriters Symbol.

Underwriters Symbol

A logotype denoting that the product has been recognized by Underwriters Laboratory Inc. (UL).

UV Cure

Polymerizing hardening or cross inking a material by exposing to ultraviolet light.

V-Scoring (Scoring)

A board profiling process that involves cutting straight tapered lines from both sides of board, suitable for medium to large volume production with panels requiring only straight-line cuts. With this process, minimum space is needed between units and the panel can be assembled as a larger board.


A plated thru hole that is used as an inner layer connection but doesn’t have a component lead in it.


The absence of substances in a localized area (e.g., air bubbles).


The longer glass threads inside the PCB laminate. The direction is marked on the prepreg to ensure all the fibers in the multilayer build go the same direction.


Warping generally refers to finished board warp and twist. All boards may have a certain degree of warp because of manufacturing. Customers will specify the warping tolerance. same direction reducing warpage and shrinkage.

Wave Soldering

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


The shorter glass cross fibers in the PCB laminate.


Migration of conductive copper chemicals into the glass fibers of the insulating material around a drilled hole.


Work In Progress

Wire Bonding

A method used to attach very fine wire to semiconductor components (dice) to interconnect these components with each other or with package leads. The gold or aluminum wires 1 to 2 mils in diameter.

Young’s Modules

A measurement as to the amount of force an object applies as it contracts or expands due to temperature change, expressed in Mpsi or Gpa.

Zero Defects Sampling

A statistical based attribute sampling plan where a given sample of parts is inspected and any defects found are cause for rejection of the entire lot.