There are many technical terms within the surface mount assembly industry which are often used but not always widely understood. Below is a list of some of the terms and abbreviations with their meanings:-
Active Components: This refers to a type of component that is dependent on the flow direction of an electrical current. For example, a transistor, rectifier or valve.
Additive Process: Deposition or addition of conductive material onto clad or unclad base material.
ALIVH: Short for 'any layer inner via hole', this is a type of technology used to build multi-layer PCBs. This method uses a solder to create an electrical connection between PCB layers. ALIVH often replaces traditional vias and is a useful production method for creating high-density PCBs.
Ambient: The surrounding environment coming into contact with the system or component in question.
Analog Circuit: It refers to circuits processing analog signals (continuous and variable signal). The output is non-binary within this type of circuit.
Annular Ring: This term refers to the copper pad area that is left after a hole is drilled through it. This ring is measured from the edge of the pad to the edge of the hole and is an important consideration in PCB design, as it allows an electrical connection to be made from one side of the hole to the other.
Anti-Solder Ball: This type of technology is commonly applied in SMT production lines with the goal of limiting the amount of tin involved in the stencil process. This is done by making a stencil on the board and creating openings at places where the solder ball tends to be produced so that the tin paste will flow to the openings.
AOI: Short for automated optical inspection, AOI refers to a type of inspection method used to find potential problems concerning soldering performance in multi-layer PCBs with components mounted on. The AOI equipment finds these issues by capturing images of the inner PCB surfaces, looking for any possible issues in terms of displacement, polarity etc.
AQL: Short for acceptance quality limit, AQL refers to the acceptable number of defective boards produced within a production run. These are identified, counted and removed during inspection. AQL is an important figure for monitoring the quality of an assembler's production practices.
Array: This word refers to the combination of multiple copies of the same PCB into a connected matrix of boards. An array may also be referred to as a panelized, stepped out or palletized PCBs. By assembling boards this way, the assembly process can be completed much more quickly. The Array # Up, in turn, refers to how many PCBs are included in the array.
Artwork: An accurately scaled configuration of electronic data used to produce the artwork master or production master.
Artwork Master: The photographic image of the PCB pattern on film used to produce the circuit board, usually on a 1:1 scale.
AS9100: A standardized quality management system developed for the aviation, aerospace and defense industry suppliers that incorporates ISO-9001:2008 and industry requirements in an effort to provide improved quality and performance. Requires authorized registrar audit.
Aspect Ratio: Aspect ratio refers to the ratio between a PCB's thickness and diameter of its minimum via. It's best to keep aspect ratios low to improve plating quality and minimize potential via failures.
Assembly: A process involving a series of procedures where components and accessories are placed on a PCB, resulting in a functional board.
Assembly Drawing: An assembly drawing is a reference depicting the assembly requirements of a PCB. These drawings will usually include the placements of components as well as the construction technologies, methods and parameters needed to make it happen.
Assembly House: A name used to refer to a manufacturing facility where PCBs and components are assembled. These houses will usually contain PCBA equipment such as a printer, mounter, reflow oven, and more.
B-Stage: An intermediate stage in the reaction of a thermosetting resin in which the material softens when heated and swells, but does not entirely fuse or dissolve, when it is in contact with certain liquids.
Back Drilling: Primarily applied in multi-layer PCB fabrication, back-drilling helps improve signal integrity by removing stubs from plated through-holes. These stubs are unnecessary portions of via that extend into the hole, potentially causing reflections and other disturbances that damage signals.
Backplane: This is a supporting plane on a circuit board that plays an insulating role.
Barrel: The cylinder formed by plating the walls of a drilled hole.
BGA: Short for ball grid array, this is a type of component packaging used in integrated circuits (ICs) for surface mounting. They can ensure high-speed efficiency since they use columns of balls instead of pins. BGAs are usually used to mount devices like microprocessors on PCBs permanently.
Bare Board: This term refers to a circuit board with no components mounted on it.
Base Material: The insulating material used to form the conductive pattern. 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: 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.
Blind Via: A blind via is a through-hole that connects inner layers, but it can't be seen from the exterior of the PCB.
Blister: A localized swelling and/or separation between any of the layers of a laminated base material, or between base material or conductive foil. It is a form of Delamination.
Board: This is a shortened term for printed circuit board. This word also indicates the substrate upon which the PCB is printed. The board is an important electronic part, acting as a carrier for an electric connection between electronic components.
Board House: This is another name for the facility where PCB boards are fabricated.
Board Type (Single Unit and Panel): This indicates the manufacturing method of a PCB in terms of volume. Usually, a board is classified into one of two types: single unit or panel. In single unit manufacturing, PCBs are fabricated one by one. In panel manufacturing, on the other hand, multiple units of PCBs are manufactured in a single panel.
Body: A word used to describe the central section of an electronic component. It does not include the component's pins, leads or accessory parts.
Bond Strength: The force per unit area required to separate two adjacent layers of a board by a force perpendicular to the board surface.
Border Area: The region of a base material that is external to that of the end product being fabricated within it.
Bow: The deviation from flatness of a board characterized by a roughly cylindrical or spherical curvature such that, if the product is rectangle, its four corners are in the same plane.
Buried Resistance Board: The term refers to a printed circuit board with resistors buried inside. This design improves the integrity of resistant components to improve the overall function and reliability of the PCB.
Buried Via: This term is used to refer to a via connecting a top layer to one or more inner layers. In other words, a buried via can only be seen from one side of the board when looking at it from the outside.
Burr: A ridge surrounding the hole left on the outside copper surface after drilling.
C-Stage Resin: A resin in its final state of cure.
Cable: Another word for a wire that is capable of transmitting electricity or heat.
CAD: An acronym for computer-aided design, CAD refers to a designer's use of computer and pattern equipment to develop and implement a PCB layout. The result is a three-dimensional graphic of the design, which, in this case, is the layout of a PCB.
CAE: An acronym for computer-assisted engineering that refers to schematic software packages used to develop and visualize PCB designs.
CAM Files: CAM is an acronym for computer-aided manufacturing, and the files produced by this software are used for PCB manufacturing. There are multiple types of CAM files, including Gerber files for photoplotters and NC Drill files for NC Drill machines. These files are usually sent off to board and assembly houses for refinement and eventual manufacturing.
Capacitance: The property of a system of conductors and dielectrics that allows the storage of electricity when a potential difference exists between the conductors.
Carbon Mask: This is a type of conductive carbon paste that is added to the surface of a pad. Made with a combination of resin and carbon toner, carbon masks are heat-cured and are typically applied to jumpers, keys, etc.
Ceramic Substrate Printed Board: This type of board is made with a ceramic substrate, to which other materials are bonded with alumina or aluminum nitride. The primary selling points for ceramic substrate boards are their excellent insulation capabilities, thermal conductivity, soft solderability and adhesive strength.
Castellated Holes: Plated or non-plated edge of the board that includes a portion of each of a series of drilled
Catalyst: A chemical that is used to initiate the reaction or increase the speed of the reaction between a resin and a curing agent.
Cavity Process: Process that allows for portions on the inner-layers to be exposed. The exposed areas may have a surface finish and soldermask applied if required. Typically if there are holes within these areas they will need to be plugged and capped with copper, if possible avoid holes within the exposed areas.
Center to Center Spacing: The nominal distance between the centers of adjacent features on any single layer of a printed board, e.g.; gold fingers and surface mounts.
Check Plots: This is a list of check items that are based on which quality control inspection or test is implemented.
COB: Shorthand for chip-on-board, this term is a type of bare chip SMT technology. COB involves directly mounting integrated circuits to a PCB instead of packaging them first. Common in mass-produced gadgets and toys, COB can be identified by a black glob of plastic on a PCB, called a glob top. Underneath the glob, the chip connects to the board with fine wires.
Circuit: It refers to a conductive loop composed of metal leads and electronic components. It falls into one of two categories: DC circuits and AC circuits.
Clad: A copper object on a printed circuit board. Specifying certain text items for a board to be "in clad," means that the text should be made of copper, not silkscreen.
Class 3: High Reliability Electronic Products where continued operation or performance on demand is critical. (i.e. Flight controls or life support)
Clearance Hole: A hole in the conductive pattern that is larger than, and coaxial with a hole in the base material of a printed board.
CNC (Computer Numerical Control): A system that utilizes a computer and software as the primary numerical control technique.
Coating: A coating is a solid continuous film that either protects, insulates or decorates the PCB.
Component: Alternatively called electronic components or parts, components are basic pieces that can be used to build electronic equipment and devices. Examples include resistors, capacitors, potentiometers, valves, radiators, etc.
Component Hole: This is a plated hole in a PCB that is made for a component. These holes are intended to facilitate either a component pin, termination or wire with an electric connection.
Component Library: It's a collection of components as represented in a CAD software system. It's stored in a computer data file for later use.
Component Side: This refers to the side of a PCB that contains components. The opposite side contains soldering points for components.
Conductive Pattern: The configuration pattern or design of the conductive material on a base material. (This includes conductors, lands, vias, heat sinks and passive components when those are integral parts of the printed board manufacturing process.
Conductor Spacing: The observable distance between adjacent edges (not center to center spacing) of isolated patterns in a conductor layer.
Continuity: An uninterrupted path for the flow of electrical current in a circuit.
Conformal Coating: An insulating & protective coating that conforms to the configuration of the object coated and is applied on the completed board assembly.
Connection: One leg of a net.
Connector: This term refers to a transmitting component that connects two or more active components in an assembly. Usually, connectors consist of a plug and receptacle, which can be easily joined and separated.
Controlled Depth Drilling: Process for drilling partially through the thickness of the boards.
Controlled Impedance: The matching of substrate material properties with trace dimensions and locations in an effort to create specific electric impedance for a signal moving along a trace.
Controlled Dielectric: Specified thickness of the insulating layers between a signal and power or ground planes.
Copper Weight: This term is used to indicate thickness of copper foil on each layer of a PCB. It's typically expressed in ounces of copper per square foot.
Cores < .004": Requirement in controlled dielectric or controlled impedance applications for cores that are less than .004". These may require special handling and processing.
Core Thickness: The thickness of the laminate base without copper.
Countersink Holes: These are cone-shaped holes that are drilled into a PCB. To allow a countersunk screw to sit flush with the PCB surface.
Counterbored Holes: These cylindrical holes are meant to be used with a fastener so that the fastener sits flush with the PCB surface.
Cover Coat: Layer of dielectric that covers the surface (one or both sides) of the board. This can be used when the boards need to be insulated from adjacent conductive surfaces (i.e. heat sinks) or in very high voltage applications.
Crosshatching: The breaking up of large conductive area by the use of a pattern of voids in the conductive material.
CTE – (Coefficient of Thermal Expansion): The measure of the amount a material changes in any axis per degree of temperature change.
Curing: The act of applying heat and pressure to the laminate materials in order to produce a bond.
Cutout: This is a groove that is dug on a PCB.
Database: A collection of interrelated data items stored together without unnecessary redundancy, to serve one or more applications.
Date Code: Marking of products to indicate their date of manufacture. ACI standard is WWYY(weekweekyearyear).
Datum: The theoretically-exact point, axis or plane that is the origin from which the location of geometric characteristics of features of a part are established.
Daughter Board: The "daughter" of a "mother" board, a daughter board contains plugs, pins, sockets and connectors and plays a big role in internal connections for electronic devices and computers.
Decal: Another word for a graphic representation of an electronic component, which can also be called a footprint.
Delamination: A separation between plies within a base material, between a base material and a conductive foil, or any other planner separation with a printed board.
Design Rule Checking: The use of a computer-aided program to perform continuity verification of all conductors 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. It leaves irregularly shaped mounds separated by areas of thin solder. The base material is not exposed.
Dielectric: A material with a high resistance to the flow current, and which is capable of being polarized by an electrical field.
Digital Circuit: The alternative to an analog circuit. Digital circuits operate in a binary fashion like a switch, exhibiting one of two results as a consequence of an input. This is a typical circuit for computers and similar equipment.
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.
Dimensioned Hole: A hole in a printed board whose location is determined by physical dimensions or coordinate values that do not necessarily coincide with the stated grid.
DIP: An abbreviation for a dual in-line package, a DIP is a kind of housing for integrated circuits. This housing will typically come in the form of a molded plastic container with two rows of attachment pins.
Double-Sided PCB: A type of PCB that features traces and pads on both sides, rather than a single side.
DRC: An acronym for design rule check, this is a software verification of a PCB layout. These are often used on PCB designs before production to ensure the design doesn't contain any potential sources of error, like small drill holes or traces placed too close together.
Drill Hits: This is another way to refer to where holes will be drilled in a PCB design.
Dry-Film Resists: Coating material specifically designed for use in the manufacture of printed circuit boards and chemically machined parts. They are resistant to various electroplating and etching processes.
Dry Film Solder Mask: This is a type of solder mask film that is applied to a printed board that results in a higher resolution mask with finer line designs. This method tends to be more expensive than liquid solder masks.
Edge Connector: This type of connector is designed for the edge of a PCB, and it is most often used to facilitate an add-on card.
Edge Plating: This is a term used for copper plating that stretches from the top to the bottom of a surface and along the edges of a board, allowing for edge soldering and connections.
Electroconductive Paste Printed Board: This term is used to describe PCBs that are manufactured using a silkscreen printing method. The process involves applying an electroconductive printing paste to set traces and to implement stable through-hole connections.
Electrical Test: Learn how your printed circuit boards are tested to ensure their quality.
Electro-deposition: The deposition of a conductive material from a plating solution by the application of electrical current.
Electro Less Deposition: The deposition of conductive material from an autocatalytic plating solution without the application of electrical 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 direct current (DC) voltage source. The metal to be deposited is similarly immersed and connected to the other terminal.
Etchback: The controlled removal by a chemical process, to a specific depth, of nonmetallic materials from the sidewalls of holes in order to remove resin smear and to expose additional internal conductor surfaces.
Etching: The chemical, or chemical and electrolytic, removal of unwanted portions of conductive or resistive material.
EMC: An acronym for electromagnetic compatibility, EMC refers to the capability of a piece of equipment or system to run without producing excessive electromagnetic interference. Too much electromagnetic interference can interfere with or damage other pieces of equipment within the same electromagnetic environment.
ESD: A shorthand for electrostatic discharge, which is caused by static electricity.
External Layer: Also called an outer layer, an external layer is a layer on the outside of copper to which components attach.
Fabrication Drawing: This drawing is a way for designers to communicate a PCB design to engineers and workers. It will typically include an illustration of the board, locations and information about holes to be drilled, notes about the materials and methods involved, etc.
Fiducial Mark: A printed board feature (or features) that is created in the same process as the conductive pattern and that provides a common measurable point for component mounting with respect to a land pattern or land patterns.
Fine Pitch: This term refers to a class of chip packages with micro-spacing between leads, typically below 0.050 inches.
Finger: These are metal pads found along the edge of a board. These are typically used when trying to connect two circuit boards together to expand the capacity of a computer, for example.
First Article: This is what the first manufactured board is called. First articles are usually produced in small groups before volume production begins so that designers and engineers can inspect the product for potential errors or performance problems.
Flying Probe: A type of bare board electrical test machine that uses probes on the ends of mechanical arms to locate and touch the pads on the board. The probes move quickly across the board verifying continuity of each net as well as resistance to adjacent nets.
FR-1: A paper material with a phenolic resin binder. FR-1 has a TG of about 130°C.
FR-2: A paper material with phenolic resin binder similar to FR-1 - but with a TG of about 105°C.
FR-3: A paper material that is similar to FR-2 - except that an epoxy resin is used instead of phenolic resin as a binder. Used mainly in Europe.
FR-4: The UL-designated rating for a laminate composed of glass and epoxy that meets a specific standard for flammability. FR-4 is the most common dielectric material used in the construction of PCBs.
Functional Test: Alternatively called behavioral test, functional test is designed to determine how well a product's attributes meet design demands.
G10: A laminate consisting of woven epoxy-glass cloth impregnated with epoxy resin under pressure and heat. G10 lacks the anti-flammability properties of FR-4. Used mainly for thin circuits such as in watches.
Gerber File: A type of CAM file used to control a photoplotter. It's a standard way of communicating board specifications with manufacturers.
Glob Top: This refers to a "glob, " a small ball of non-conductive plastic used to protect the chip and wire bonds on a COB. The glob is usually black in color and is resistant to thermal expansion, which prevents temperature changes from damaging the connection between the glob and the board.
Gold Fingers: These are connectors found on the edge of a PCB after the board has been plated with gold. Hard, smooth and flat, these fingers are excellent conductors, supporting edge-to-edge connections.
Grid: "Grid" is another term for an electrical grid, an interconnected electrical network that transmits power.
Ground: A common reference point for electrical circuits returns, shielding or heat sinking.
Ground Plane: A conductor layer, or portion thereof that serves as a common reference for electrical circuit returns, shielding or heat sinking.
Half-Cut/Castellated Holes: This refers to holes that are drilled on the edge of a board and plated, resulting in a half-circle hole on the edge of the PCB. This is common for PCBs designed for microchip testing.
HASL – (Hot Air Solder Leveling): A method of coating exposed copper with solder by inserting a panel into a bath of molten solder then passing the panel rapidly past jets of hot air.
HDI: An acronym for high-density interconnector, an HDI is a type of PCB fabrication technology. It uses micro blind via technology to manufacture PCBs with high trace density.
Header: The portion of a connector assembly that mounts directly to the printed circuit.
Hole Breakout: A condition in which a hole is not completely surrounded by the land.
Hole Density: The quantity of holes in a unit area of a printed board.
IC: Short for integrated circuit, an IC is also called microcircuit, microchip or chip. Essentially, IC describes a method for miniaturizing circuits, especially for semiconductor devices.
Imaging: The process of transferring electronic data to the photo-plotter, which in turn uses light to transfer a negative image circuitry pattern onto the panel or film.
Immersion Plating: The chemical deposition of a thin metallic coating over certain basis metals that is achieved by a partial displacement of the basis metal.
Impedance: The resistance to the flow of current, represented by an electrical network of combined resistance, capacitance and inductance reaction, in a conductor as seen by an AC source of varying time voltage. The unit of measure is ohms.
Inclusions: Foreign particles, metallic or nonmetallic, that may be entrapped in an insulating material, conductive layer, plating, base material, or solder connection.
Inkjetting: The dispersal of well-defined ink "dots" onto a PCB. Inkjet equipment uses heat to liquefy a solid ink pellet and change the ink into a liquid, which is then dropped via a nozzle onto the printed surface, where it quickly dries.
Inner-Layers: The internal layers of laminate and metal foil within a multi-layer board.
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.
IPC: An abbreviation of Institute of Printed Circuits, a worldwide non-profit association dedicated to the design of PCB wiring. The group helps enterprises achieve greater business success by helping them meet rigorous manufacturing standards, which, in turn, improve overall quality standards.
Kapton tape: Alternatively called polyimide tape, this electrically insulating tape has numerous useful features, including heat resistance, inextensibility and thinness.
Laminate: This term refers to the combination of different materials through heating, adhesive and welding methods to create a new material with multiple layers. The resulting material has greater strength and stability than the individual materials combined to create the laminate.
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 that 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 a pad.
Laser Photo-Plotter: A plotter that uses a laser, which simulates a vector photo-plotter by using software to create a raster image of the individual objects in a CAD database, then plots the image as a series of lines of dots at a very fine resolution. A laser photo-plotter is capable of more accurate and consistent plots than a vector plotter.
Lead: A terminal on a component.
Legend: A format of lettering or symbols on the printed circuit board: e.g. part number, serial number, component locations, and patterns.
LFHASL or LFHAL: Lead-Free-Hot-Air-Solder-Level or Lead-Free-Hot-Air-Level is similar to HASL in appearance and usage; however, the solder in this case contains a mix of 99.3% Tin and 0.6% Copper.
LPI – (Liquid Photo-Imageable Solder Mask): An ink that is developed off using photographic imaging techniques to control deposition. It is the most accurate method of mask application and results in a thinner mask than dry film solder mask. It is often preferred for dense SMT. Application can be spray, curtain coat or squeegee.
Laser Photoplotter: Alternatively called a laser plotter, this type of photoplotter creates a finely-lined raster image of the end product. The result is a high-quality, highly accurate plot.
Layer-to-Layer Spacing: This is the distance between PCB layers. The lower the spacing, the more difficult the manufacturing process will be.
Lead: Another word for a terminal on a component.
Legend: This is a shorthand guide for marking component names and positions. Legends help ease the assembly and maintenance processes.
LPI: Shorthand for Liquid Photoimageable, an LPI is a liquid solder mask that is sprayed on a PCB. This method is more accurate, thinner than a dry film solder mask and more affordable.
Mask: A material applied to enable selective etching, plating, or the application of solder to a PCB. Also called solder mask or resist.
Mark: A term used to refer to a set of patterns for optical localization. Marks can be classified into PCB Marks and local Marks.
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.
Membrane Switch: A membrane switch is applied to the front of a finished PCB. It indicates functions of the PCB and components, such as key functions, indicators and other parts. The membrane also provides protection for the PCB in the form of waterproofing and humidity protection.
Metal Base/Core Printed Board: Metal core PCB refers to a type of PCB with a core material made of metal instead of plastic, resin or FR4 material.
Metal Foil: The plane of conductive material of a printed board from which circuits are formed. Metal foil is generally copper and is provided in sheets or rolls.
Micro-Sectioning: The preparation of a specimen of a material, or materials, 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 0.005" or less that connects layers of a multi-layer PCB. Often used to refer to any small geometry connection holes created by laser drilling.
Mil: A "mil" is another way to say a thousandth of an inch. It's also the equivalent of a "thou. "
mm: "mm" is another way to express a millimeter or a thousandth of a meter.
Motherboard: This is the main board in a computer or electric device. The motherboard carries key interconnections and components that support the primary functions of the device.
Mounting Hole: This hole is intended to secure the PCB to its final location in a device. To ensure there is no interference, all mounting holes are non-conductive and unplated.
Multi-Layer PCB: This is a type of PCB with at least three conductive layers of trace and components.
Multimeter: A testing tool used to measure electrical values like current, resistance and voltage.
Multi-Wiring Printed Board: An equivalent to a multi-layer printed circuit board, this term refers to PCBs with multiple layers of trace, with dielectric layers between each.
NC Drill: This is a more common name for a Numeric Control drill machine. This type of machine is what assemblers use to drill holes in PCBs.
Negative: A reverse-image copy of a positive, useful for checking revisions of a PCB and is often used for representing inner layer planes. When a negative image is used for an inner-layer it would typically have clearances (solid circles) and thermals(segmented donuts) that either isolate holes from the plane or make thermally relieved connections respectively.
Net: A collection of terminals all of which are, or must be, connected electrically. Also known as signal.
Netlist: List of names of symbols or parts and their connection points which are logically connected in each net of a circuit. A netlist can be captured from properly prepared schematic-drawing files of an electrical CAE application.
Nomenclature: Identification symbols applied to the board by means of screen printing, inkjetting, or laser processes. See Legend.
Node: This is a pin or lead that is connected to at least one wire.
NPTH: An acronym for non-plated through hole, NPTH refers to a hole with no plated copper on the hole wall. This means no electric connections can be made using the walls of this hole.
Open: This is a short way of saying "open circuit, " which is a break in an electrical circuit's continuity. This prevents current from flowing and can disrupt the proper function of a PCB.
Outer-Layer: The top and bottom sides of any type of circuit board.
Pad: This is one of the most basic composition units of a PCB assembly. A pad is a contact point used to connect components with a via and is the point to which the components are soldered.
Panel: A panel is a combination of boards produced simultaneously to improve efficiency during the manufacturing process. Once the process is finished, these panels are typically broken apart into their singular units before being used.
Pattern: The configuration of conductive and nonconductive materials on a panel or printed board. Also, the circuit configuration on related tools, drawing, and masters.
Pattern Plating: The selective plating of a conductive pattern.
Panelize: This is the act of grouping multiple PCBs into a panel to improve manufacturing efficiency. An alternative term is panelization.
Part Number: This is an identification method used in industry to differentiate parts from one another. It's also used to identify specific parts, which is helpful in identifying problematic assembly batches and preventing incorrect product applications.
Part: This is another word for a component, or a basic piece of electric equipment, such as a resistor, capacitor, potentiometer, valve, radiator, etc.
PCB Array: Boards supplied in pallet form, sometimes called "panelized", "stepped out", "palletized" and "rout and retain
PCB Prototype: A printed circuit board fabricated especially for use in testing. In some cases, a printed circuit board manufactured rapidly for a specific application.
PCB Base Material: The material upon which the PCB is built. The PCB base material is typically composed of resin, metal, ceramic or another material with thermal and electric properties that support the PCB's final function.
PCB Database: All the data that is or could be used for a PCB design. This data is usually stored in a computer file.
PCB: An abbreviation of Printed Circuit Board, a PCB is a board that contains a conductive material and components, which act in synchrony to produce a designed response. PCBs rely on electrical circuits, which are either printed or soldered onto the board to elicit the desired result. Printed circuit boards are available in a wide variety of shapes, sizes and purposes to suit any industry or application.
PCBA: This is an acronym for Printed Circuit Board Assembly, where a company solders components to boards.
Peelable Solder Mask: A solder mask or layer of solder mask that can be peeled from the board.
Photoplotter: A device used in manufacturing to produce artwork onto film by plotting objects instead of images.
Photo Resist: A material that is sensitive to portions of the light spectrum and that, when properly exposed can mask portions of a base metal with a high degree of integrity.
Phototool: A transparent film that contains the circuit pattern, which is represented by a series of lines of dots at a high resolution.
Pick-And-Place: A method of SMT assembly where a machine automatically picks up SMDs and places them in the correct positions on the board.
Pin: A terminal on a component. It is also called a lead.
Pitch: The distance between pin centers of SMDs.
Plating: The chemical or electrochemical deposited metal on a surface.
Plated-Through Hole: Alternatively called a PTH, this is a procedure in which a through-hole is plated so that the hole wall can be conductive. This is often used as a contact point for through-hole components and can be used as a via.
Positive: A developed image of photo-plotted file, where the areas selectively exposed by the photo plotter appear black and unexposed areas are clear. For outer-layers, color will indicate copper. Positive inner-layers will have clear areas to indicate copper.
Prepreg: Also called PP, is the key material for multi-layer PCB manufacturing. it is primarily composed of resin and strengthening material that is then classified into glass-fiber cloth, paper base, compound material etc.
Press Fit Holes: This is a hole through which a contact terminal can be pressed into a PCB.
Printed Wiring: A process where a design is etched into conductive metal on a board, producing a wire design for the PCB.
Probe Test: A spring-loaded metal device used to make electrical contact between test equipment and the unit under test.
Printing: Part of the PCB manufacturing process where a circuit pattern is printed on the board.
Pulse Plating: A method of plating that uses pulses instead of a direct current.
PWB: An acronym for Printed Wiring Board, which is another name for a PCB.
Quick Turn: Fast turnaround PCB manufacturing. As a leading printed circuit board manufacturer in the USA, Advanced Circuits provides rapid PCB manufacturing and assembly services.
Reference Designator: Alternatively called "Ref Des, " this is the name of a component on a PCB. Typically, the component name begins with a letter or two, indicating the component class, followed by a number. These designators are usually printed on the silkscreen to help identify each component.
Reference Dimension: A dimension without a tolerance that is used only for informational purposes that does not govern inspection or other manufacturing operations.
Resist: A coating material that is used to mask or protect select areas of a pattern during manufacturing or testing from the action of an etchant, plating, solder, etc.
Reflow: This is the process of melting solder to create a joint between a pad and a component or lead.
RF: Short for radio frequency, RF is an electromagnetic frequency ranging between 300KHz and 300GHz. RF can also be a type of high-frequency electromagnetic signal.
RoHS: Alternatively known as the Restriction of Hazardous Substances, RoHS is a European environmental protection law. Many global companies must follow RoHS standards to sell products in the EU.
Rout: A layout or wiring of a connection. The action of creating such a wiring. The term is also used for the actual milling of a PCB.
Route/Track: This is the layout of a PCB's wiring structure, which is important for the proper function of the PCB. As a verb, the act of routing means designing such wiring structures.
Schematic: A technical drawing that illustrates the connections between PCB components. Schematics will often include abstract representations of components instead of pictures and is an important first step in PCB design.
Scoring: A technique in which grooves are machined on opposite sides of a panel to a depth that permits individual boards to be separated from the panel after component assembly.
Screen Printing: A process for transferring an image to a surface by forcing suitable media through a stencil screen with a squeegee.
Short: This is an alternative way to say "short circuit, " which is a connection with low resistance, resulting in excess current at the connecting point. This can cause serious problems in the PCB, including failure.
Silkscreen: This is a layer of epoxy ink applied to a PCB that contains component names and positions. The labels included on silkscreens help to direct workers through the assembly process. Typically, silkscreens are white, which helps the labels stand out against the PCB's solder mask.
Single-Sided PCB: A PCB design with traces and pads included on only one side of the board.
Slot Hole: Non-round holes on a PCB that may or may not be plated. These are often required for specific components but are costly due to the labor needed to cut them.
SMOBC –(Solder Mask Over Bare Copper): A method of fabricating a printed circuit board that results in final metallization being copper 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 mask.
SMD: Short for surface mount devices, it refers to components designed to be soldered on the surface of PCBs, rather than through a thru-hole.
SMT: Short for surface mount technology, this type of assembly technology directly solders SMDs to the surface of a PCB, rather than running components through thru-holes. This allows the board to function without drilling holes through it and also helps improve component density on the surface of the PCB.
Solder: An alloy that melts at relatively low temperatures and is used to join or seal metals with higher melting points.
Solder Coat: A layer of solder that is applied directly from a molten solder bath to a conductive pattern.
Solder Leveling: The process by which the board is exposed to hot oil or hot air to remove excess solder from holes and lands.
Solder Paste Stencils: Stencils ensure the right amount of solder paste is applied to achieve optimal electrical connections.
Solder Mask/Solder Resist: This is a layer of material, usually consisting of an epoxy resin, which isn't compatible with solder. This material is applied to the entire PCB, except those areas where content needs to be soldered. This process helps to physically and electrically insulate traces, preventing shorts. Solder masks are often green in color, though red and black are also common.
Solder Side: This is the opposite of the component side and is usually regarded as the bottom side.
Spacing: This term refers to the distance between wires on a PCB.
Step–and–Repeat: The successive exposure of a single image on order to produce a multiple-image production master. Also used in CNC programs.
Sub–Panel: A group of printed circuits arrayed in a panel and handled by both the board house and the assembly house as though it were a single printed wiring board. The sub-panel is usually prepared at the board house by routing most of the material separating individual modules leaving small tabs.
Surface Mount: Surface mount technology. Components are soldered to the board without using holes. The result is higher component density, allowing smaller PWBs. Abbreviated SMT.
Substrate: This is another word for "PCB base material", the primary material for PCB fabrication. Generally, this material can be flexible or rigid and can be made of epoxy, metal, ceramic or other materials. The function of the end PCB will usually determine which substrate will be used for the project.
Supported Hole: This is a via with pads on both sides of the PCB. It's also plated inside the via. This means the entire hole can support functions relating to thermal or electrical conductivity.
Surface Finish: Since copper tends to oxidize in natural environments, a surface finish protects the layer from doing so. Oxidation can cause the tin paste to fail or solder incorrectly. The primary types of surface finishes include HASL, ENIG, IMAG, OSP and others.
Tented Via: This is a type of via that has a dry film solder mask covering both its pad and its plated-thru hole. This solder mask insulates the via completely, protecting the PCB against shorts. Some vias are tented only on one side to allow for testing on the other.
Tenting: The covering of holes in a printed board and the surrounding conductive pattern with a dry film resist.
Terminal: A point of connection for two or more conductors in an electrical circuit; one of the conductors is usually an electrical contact or lead of a component.
Test Board: A printed board that is deemed to be suitable for determining the acceptability of a group of boards that were. Or will be, produced with the same fabrication process.
Test Fixture: A device that interfaces between test equipment and the unit under test.
TG: Glass transition temperature. The point at which rising temperatures cause resin inside the solid base laminate to start to exhibit soft, plastic-like symptoms. This is expressed in degrees Celsius (°C).
Thou: This is shorthand for a thousandth of an inch. It's another way to say "mil. "
Through-Hole/Thru-Hole: This refers to a hole passing through at least two layers of a multi-layer PCB. It's also used as a descriptor for components with parts or pins that run through a board to be soldered to another side.
Trace/Track: This refers to the copper path printed on a PCB. It functions similarly to an electrical wire, connecting components on a PCB board. The word "trace" is also used to refer to a segment of the path.
Tracing: This term refers to the width of a PCB's wires.
UL: UL stands for Underwriter's Laboratories, Inc., a renowned company specializing in establishing safety standards and independently assessing products according to these standards.
Unsupported Hole: This type of hole has a pad on the solder side, but no pad on the component side. There is also no metal layer inside the hole. This means the hole has no conductive reinforcement.
Vector Photoplotter: Alternatively called a vector plotter or Gerber Photoplotter, this type of photoplotter draws a plot line by line using light manipulation technology. This method can produce larger plots, but it is also much slower than the more modern laser photoplotter method.
Via: This term refers to plated through-holes that connect signals between traces on different layers of a PCB. These holes have conductive copper interiors to maintain an electrical connection.
Via Filled With Resin/Via Plugged: This is a via that is filled with an epoxy resin. Once filled, copper can be soldered to the surface of the resin without influencing the final product.
Via in Pad: Also called a thru-hole on the pad, a via in pad functions as an electric connection between layers. It is useful for multi-layer components or for fixing the positions of components.
Void: The absence of any substances in a localized area. (Ex: missing plating in a hole)
V-Scoring: This is an incomplete cut through a panel, which is often used to help break apart panels of PCBs into single units.
Wave Soldering: Assembled printed boards are brought in contact with a continuously flowing and circulating mass of solder, typically in a bath to connect the leads of components to through hole pads and barrels.
Wicking: Migration of copper salts into the glass fibers of the insulating material found in the barrel of a plated hole.
Wire: This refers to a conductive cable that can transmit electricity or heat. It also refers to a route or track on a printed circuit board.
X-Axis: The horizontal or left-to-right direction in a two-dimensional system of coordinates.
Y-Axis: The vertical or bottom-to-top direction in a two-dimensional system of coordinates.
Z-Axis: The axis perpendicular to the plane formed by the X and Y datum reference. This axis usually represents the thickness of the boards.
Additive Process: Deposition or addition of conductive material onto clad or unclad base material.
ALIVH: Short for 'any layer inner via hole', this is a type of technology used to build multi-layer PCBs. This method uses a solder to create an electrical connection between PCB layers. ALIVH often replaces traditional vias and is a useful production method for creating high-density PCBs.
Ambient: The surrounding environment coming into contact with the system or component in question.
Analog Circuit: It refers to circuits processing analog signals (continuous and variable signal). The output is non-binary within this type of circuit.
Annular Ring: This term refers to the copper pad area that is left after a hole is drilled through it. This ring is measured from the edge of the pad to the edge of the hole and is an important consideration in PCB design, as it allows an electrical connection to be made from one side of the hole to the other.
Anti-Solder Ball: This type of technology is commonly applied in SMT production lines with the goal of limiting the amount of tin involved in the stencil process. This is done by making a stencil on the board and creating openings at places where the solder ball tends to be produced so that the tin paste will flow to the openings.
AOI: Short for automated optical inspection, AOI refers to a type of inspection method used to find potential problems concerning soldering performance in multi-layer PCBs with components mounted on. The AOI equipment finds these issues by capturing images of the inner PCB surfaces, looking for any possible issues in terms of displacement, polarity etc.
AQL: Short for acceptance quality limit, AQL refers to the acceptable number of defective boards produced within a production run. These are identified, counted and removed during inspection. AQL is an important figure for monitoring the quality of an assembler's production practices.
Array: This word refers to the combination of multiple copies of the same PCB into a connected matrix of boards. An array may also be referred to as a panelized, stepped out or palletized PCBs. By assembling boards this way, the assembly process can be completed much more quickly. The Array # Up, in turn, refers to how many PCBs are included in the array.
Artwork: An accurately scaled configuration of electronic data used to produce the artwork master or production master.
Artwork Master: The photographic image of the PCB pattern on film used to produce the circuit board, usually on a 1:1 scale.
AS9100: A standardized quality management system developed for the aviation, aerospace and defense industry suppliers that incorporates ISO-9001:2008 and industry requirements in an effort to provide improved quality and performance. Requires authorized registrar audit.
Aspect Ratio: Aspect ratio refers to the ratio between a PCB's thickness and diameter of its minimum via. It's best to keep aspect ratios low to improve plating quality and minimize potential via failures.
Assembly: A process involving a series of procedures where components and accessories are placed on a PCB, resulting in a functional board.
Assembly Drawing: An assembly drawing is a reference depicting the assembly requirements of a PCB. These drawings will usually include the placements of components as well as the construction technologies, methods and parameters needed to make it happen.
Assembly House: A name used to refer to a manufacturing facility where PCBs and components are assembled. These houses will usually contain PCBA equipment such as a printer, mounter, reflow oven, and more.
B-Stage: An intermediate stage in the reaction of a thermosetting resin in which the material softens when heated and swells, but does not entirely fuse or dissolve, when it is in contact with certain liquids.
Back Drilling: Primarily applied in multi-layer PCB fabrication, back-drilling helps improve signal integrity by removing stubs from plated through-holes. These stubs are unnecessary portions of via that extend into the hole, potentially causing reflections and other disturbances that damage signals.
Backplane: This is a supporting plane on a circuit board that plays an insulating role.
Barrel: The cylinder formed by plating the walls of a drilled hole.
BGA: Short for ball grid array, this is a type of component packaging used in integrated circuits (ICs) for surface mounting. They can ensure high-speed efficiency since they use columns of balls instead of pins. BGAs are usually used to mount devices like microprocessors on PCBs permanently.
Bare Board: This term refers to a circuit board with no components mounted on it.
Base Material: The insulating material used to form the conductive pattern. 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: 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.
Blind Via: A blind via is a through-hole that connects inner layers, but it can't be seen from the exterior of the PCB.
Blister: A localized swelling and/or separation between any of the layers of a laminated base material, or between base material or conductive foil. It is a form of Delamination.
Board: This is a shortened term for printed circuit board. This word also indicates the substrate upon which the PCB is printed. The board is an important electronic part, acting as a carrier for an electric connection between electronic components.
Board House: This is another name for the facility where PCB boards are fabricated.
Board Type (Single Unit and Panel): This indicates the manufacturing method of a PCB in terms of volume. Usually, a board is classified into one of two types: single unit or panel. In single unit manufacturing, PCBs are fabricated one by one. In panel manufacturing, on the other hand, multiple units of PCBs are manufactured in a single panel.
Body: A word used to describe the central section of an electronic component. It does not include the component's pins, leads or accessory parts.
Bond Strength: The force per unit area required to separate two adjacent layers of a board by a force perpendicular to the board surface.
Border Area: The region of a base material that is external to that of the end product being fabricated within it.
Bow: The deviation from flatness of a board characterized by a roughly cylindrical or spherical curvature such that, if the product is rectangle, its four corners are in the same plane.
Buried Resistance Board: The term refers to a printed circuit board with resistors buried inside. This design improves the integrity of resistant components to improve the overall function and reliability of the PCB.
Buried Via: This term is used to refer to a via connecting a top layer to one or more inner layers. In other words, a buried via can only be seen from one side of the board when looking at it from the outside.
Burr: A ridge surrounding the hole left on the outside copper surface after drilling.
C-Stage Resin: A resin in its final state of cure.
Cable: Another word for a wire that is capable of transmitting electricity or heat.
CAD: An acronym for computer-aided design, CAD refers to a designer's use of computer and pattern equipment to develop and implement a PCB layout. The result is a three-dimensional graphic of the design, which, in this case, is the layout of a PCB.
CAE: An acronym for computer-assisted engineering that refers to schematic software packages used to develop and visualize PCB designs.
CAM Files: CAM is an acronym for computer-aided manufacturing, and the files produced by this software are used for PCB manufacturing. There are multiple types of CAM files, including Gerber files for photoplotters and NC Drill files for NC Drill machines. These files are usually sent off to board and assembly houses for refinement and eventual manufacturing.
Capacitance: The property of a system of conductors and dielectrics that allows the storage of electricity when a potential difference exists between the conductors.
Carbon Mask: This is a type of conductive carbon paste that is added to the surface of a pad. Made with a combination of resin and carbon toner, carbon masks are heat-cured and are typically applied to jumpers, keys, etc.
Ceramic Substrate Printed Board: This type of board is made with a ceramic substrate, to which other materials are bonded with alumina or aluminum nitride. The primary selling points for ceramic substrate boards are their excellent insulation capabilities, thermal conductivity, soft solderability and adhesive strength.
Castellated Holes: Plated or non-plated edge of the board that includes a portion of each of a series of drilled
Catalyst: A chemical that is used to initiate the reaction or increase the speed of the reaction between a resin and a curing agent.
Cavity Process: Process that allows for portions on the inner-layers to be exposed. The exposed areas may have a surface finish and soldermask applied if required. Typically if there are holes within these areas they will need to be plugged and capped with copper, if possible avoid holes within the exposed areas.
Center to Center Spacing: The nominal distance between the centers of adjacent features on any single layer of a printed board, e.g.; gold fingers and surface mounts.
Check Plots: This is a list of check items that are based on which quality control inspection or test is implemented.
COB: Shorthand for chip-on-board, this term is a type of bare chip SMT technology. COB involves directly mounting integrated circuits to a PCB instead of packaging them first. Common in mass-produced gadgets and toys, COB can be identified by a black glob of plastic on a PCB, called a glob top. Underneath the glob, the chip connects to the board with fine wires.
Circuit: It refers to a conductive loop composed of metal leads and electronic components. It falls into one of two categories: DC circuits and AC circuits.
Clad: A copper object on a printed circuit board. Specifying certain text items for a board to be "in clad," means that the text should be made of copper, not silkscreen.
Class 3: High Reliability Electronic Products where continued operation or performance on demand is critical. (i.e. Flight controls or life support)
Clearance Hole: A hole in the conductive pattern that is larger than, and coaxial with a hole in the base material of a printed board.
CNC (Computer Numerical Control): A system that utilizes a computer and software as the primary numerical control technique.
Coating: A coating is a solid continuous film that either protects, insulates or decorates the PCB.
Component: Alternatively called electronic components or parts, components are basic pieces that can be used to build electronic equipment and devices. Examples include resistors, capacitors, potentiometers, valves, radiators, etc.
Component Hole: This is a plated hole in a PCB that is made for a component. These holes are intended to facilitate either a component pin, termination or wire with an electric connection.
Component Library: It's a collection of components as represented in a CAD software system. It's stored in a computer data file for later use.
Component Side: This refers to the side of a PCB that contains components. The opposite side contains soldering points for components.
Conductive Pattern: The configuration pattern or design of the conductive material on a base material. (This includes conductors, lands, vias, heat sinks and passive components when those are integral parts of the printed board manufacturing process.
Conductor Spacing: The observable distance between adjacent edges (not center to center spacing) of isolated patterns in a conductor layer.
Continuity: An uninterrupted path for the flow of electrical current in a circuit.
Conformal Coating: An insulating & protective coating that conforms to the configuration of the object coated and is applied on the completed board assembly.
Connection: One leg of a net.
Connector: This term refers to a transmitting component that connects two or more active components in an assembly. Usually, connectors consist of a plug and receptacle, which can be easily joined and separated.
Controlled Depth Drilling: Process for drilling partially through the thickness of the boards.
Controlled Impedance: The matching of substrate material properties with trace dimensions and locations in an effort to create specific electric impedance for a signal moving along a trace.
Controlled Dielectric: Specified thickness of the insulating layers between a signal and power or ground planes.
Copper Weight: This term is used to indicate thickness of copper foil on each layer of a PCB. It's typically expressed in ounces of copper per square foot.
Cores < .004": Requirement in controlled dielectric or controlled impedance applications for cores that are less than .004". These may require special handling and processing.
Core Thickness: The thickness of the laminate base without copper.
Countersink Holes: These are cone-shaped holes that are drilled into a PCB. To allow a countersunk screw to sit flush with the PCB surface.
Counterbored Holes: These cylindrical holes are meant to be used with a fastener so that the fastener sits flush with the PCB surface.
Cover Coat: Layer of dielectric that covers the surface (one or both sides) of the board. This can be used when the boards need to be insulated from adjacent conductive surfaces (i.e. heat sinks) or in very high voltage applications.
Crosshatching: The breaking up of large conductive area by the use of a pattern of voids in the conductive material.
CTE – (Coefficient of Thermal Expansion): The measure of the amount a material changes in any axis per degree of temperature change.
Curing: The act of applying heat and pressure to the laminate materials in order to produce a bond.
Cutout: This is a groove that is dug on a PCB.
Database: A collection of interrelated data items stored together without unnecessary redundancy, to serve one or more applications.
Date Code: Marking of products to indicate their date of manufacture. ACI standard is WWYY(weekweekyearyear).
Datum: The theoretically-exact point, axis or plane that is the origin from which the location of geometric characteristics of features of a part are established.
Daughter Board: The "daughter" of a "mother" board, a daughter board contains plugs, pins, sockets and connectors and plays a big role in internal connections for electronic devices and computers.
Decal: Another word for a graphic representation of an electronic component, which can also be called a footprint.
Delamination: A separation between plies within a base material, between a base material and a conductive foil, or any other planner separation with a printed board.
Design Rule Checking: The use of a computer-aided program to perform continuity verification of all conductors 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. It leaves irregularly shaped mounds separated by areas of thin solder. The base material is not exposed.
Dielectric: A material with a high resistance to the flow current, and which is capable of being polarized by an electrical field.
Digital Circuit: The alternative to an analog circuit. Digital circuits operate in a binary fashion like a switch, exhibiting one of two results as a consequence of an input. This is a typical circuit for computers and similar equipment.
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.
Dimensioned Hole: A hole in a printed board whose location is determined by physical dimensions or coordinate values that do not necessarily coincide with the stated grid.
DIP: An abbreviation for a dual in-line package, a DIP is a kind of housing for integrated circuits. This housing will typically come in the form of a molded plastic container with two rows of attachment pins.
Double-Sided PCB: A type of PCB that features traces and pads on both sides, rather than a single side.
DRC: An acronym for design rule check, this is a software verification of a PCB layout. These are often used on PCB designs before production to ensure the design doesn't contain any potential sources of error, like small drill holes or traces placed too close together.
Drill Hits: This is another way to refer to where holes will be drilled in a PCB design.
Dry-Film Resists: Coating material specifically designed for use in the manufacture of printed circuit boards and chemically machined parts. They are resistant to various electroplating and etching processes.
Dry Film Solder Mask: This is a type of solder mask film that is applied to a printed board that results in a higher resolution mask with finer line designs. This method tends to be more expensive than liquid solder masks.
Edge Connector: This type of connector is designed for the edge of a PCB, and it is most often used to facilitate an add-on card.
Edge Plating: This is a term used for copper plating that stretches from the top to the bottom of a surface and along the edges of a board, allowing for edge soldering and connections.
Electroconductive Paste Printed Board: This term is used to describe PCBs that are manufactured using a silkscreen printing method. The process involves applying an electroconductive printing paste to set traces and to implement stable through-hole connections.
Electrical Test: Learn how your printed circuit boards are tested to ensure their quality.
Electro-deposition: The deposition of a conductive material from a plating solution by the application of electrical current.
Electro Less Deposition: The deposition of conductive material from an autocatalytic plating solution without the application of electrical 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 direct current (DC) voltage source. The metal to be deposited is similarly immersed and connected to the other terminal.
Etchback: The controlled removal by a chemical process, to a specific depth, of nonmetallic materials from the sidewalls of holes in order to remove resin smear and to expose additional internal conductor surfaces.
Etching: The chemical, or chemical and electrolytic, removal of unwanted portions of conductive or resistive material.
EMC: An acronym for electromagnetic compatibility, EMC refers to the capability of a piece of equipment or system to run without producing excessive electromagnetic interference. Too much electromagnetic interference can interfere with or damage other pieces of equipment within the same electromagnetic environment.
ESD: A shorthand for electrostatic discharge, which is caused by static electricity.
External Layer: Also called an outer layer, an external layer is a layer on the outside of copper to which components attach.
Fabrication Drawing: This drawing is a way for designers to communicate a PCB design to engineers and workers. It will typically include an illustration of the board, locations and information about holes to be drilled, notes about the materials and methods involved, etc.
Fiducial Mark: A printed board feature (or features) that is created in the same process as the conductive pattern and that provides a common measurable point for component mounting with respect to a land pattern or land patterns.
Fine Pitch: This term refers to a class of chip packages with micro-spacing between leads, typically below 0.050 inches.
Finger: These are metal pads found along the edge of a board. These are typically used when trying to connect two circuit boards together to expand the capacity of a computer, for example.
First Article: This is what the first manufactured board is called. First articles are usually produced in small groups before volume production begins so that designers and engineers can inspect the product for potential errors or performance problems.
Flying Probe: A type of bare board electrical test machine that uses probes on the ends of mechanical arms to locate and touch the pads on the board. The probes move quickly across the board verifying continuity of each net as well as resistance to adjacent nets.
FR-1: A paper material with a phenolic resin binder. FR-1 has a TG of about 130°C.
FR-2: A paper material with phenolic resin binder similar to FR-1 - but with a TG of about 105°C.
FR-3: A paper material that is similar to FR-2 - except that an epoxy resin is used instead of phenolic resin as a binder. Used mainly in Europe.
FR-4: The UL-designated rating for a laminate composed of glass and epoxy that meets a specific standard for flammability. FR-4 is the most common dielectric material used in the construction of PCBs.
Functional Test: Alternatively called behavioral test, functional test is designed to determine how well a product's attributes meet design demands.
G10: A laminate consisting of woven epoxy-glass cloth impregnated with epoxy resin under pressure and heat. G10 lacks the anti-flammability properties of FR-4. Used mainly for thin circuits such as in watches.
Gerber File: A type of CAM file used to control a photoplotter. It's a standard way of communicating board specifications with manufacturers.
Glob Top: This refers to a "glob, " a small ball of non-conductive plastic used to protect the chip and wire bonds on a COB. The glob is usually black in color and is resistant to thermal expansion, which prevents temperature changes from damaging the connection between the glob and the board.
Gold Fingers: These are connectors found on the edge of a PCB after the board has been plated with gold. Hard, smooth and flat, these fingers are excellent conductors, supporting edge-to-edge connections.
Grid: "Grid" is another term for an electrical grid, an interconnected electrical network that transmits power.
Ground: A common reference point for electrical circuits returns, shielding or heat sinking.
Ground Plane: A conductor layer, or portion thereof that serves as a common reference for electrical circuit returns, shielding or heat sinking.
Half-Cut/Castellated Holes: This refers to holes that are drilled on the edge of a board and plated, resulting in a half-circle hole on the edge of the PCB. This is common for PCBs designed for microchip testing.
HASL – (Hot Air Solder Leveling): A method of coating exposed copper with solder by inserting a panel into a bath of molten solder then passing the panel rapidly past jets of hot air.
HDI: An acronym for high-density interconnector, an HDI is a type of PCB fabrication technology. It uses micro blind via technology to manufacture PCBs with high trace density.
Header: The portion of a connector assembly that mounts directly to the printed circuit.
Hole Breakout: A condition in which a hole is not completely surrounded by the land.
Hole Density: The quantity of holes in a unit area of a printed board.
IC: Short for integrated circuit, an IC is also called microcircuit, microchip or chip. Essentially, IC describes a method for miniaturizing circuits, especially for semiconductor devices.
Imaging: The process of transferring electronic data to the photo-plotter, which in turn uses light to transfer a negative image circuitry pattern onto the panel or film.
Immersion Plating: The chemical deposition of a thin metallic coating over certain basis metals that is achieved by a partial displacement of the basis metal.
Impedance: The resistance to the flow of current, represented by an electrical network of combined resistance, capacitance and inductance reaction, in a conductor as seen by an AC source of varying time voltage. The unit of measure is ohms.
Inclusions: Foreign particles, metallic or nonmetallic, that may be entrapped in an insulating material, conductive layer, plating, base material, or solder connection.
Inkjetting: The dispersal of well-defined ink "dots" onto a PCB. Inkjet equipment uses heat to liquefy a solid ink pellet and change the ink into a liquid, which is then dropped via a nozzle onto the printed surface, where it quickly dries.
Inner-Layers: The internal layers of laminate and metal foil within a multi-layer board.
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.
IPC: An abbreviation of Institute of Printed Circuits, a worldwide non-profit association dedicated to the design of PCB wiring. The group helps enterprises achieve greater business success by helping them meet rigorous manufacturing standards, which, in turn, improve overall quality standards.
Kapton tape: Alternatively called polyimide tape, this electrically insulating tape has numerous useful features, including heat resistance, inextensibility and thinness.
Laminate: This term refers to the combination of different materials through heating, adhesive and welding methods to create a new material with multiple layers. The resulting material has greater strength and stability than the individual materials combined to create the laminate.
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 that 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 a pad.
Laser Photo-Plotter: A plotter that uses a laser, which simulates a vector photo-plotter by using software to create a raster image of the individual objects in a CAD database, then plots the image as a series of lines of dots at a very fine resolution. A laser photo-plotter is capable of more accurate and consistent plots than a vector plotter.
Lead: A terminal on a component.
Legend: A format of lettering or symbols on the printed circuit board: e.g. part number, serial number, component locations, and patterns.
LFHASL or LFHAL: Lead-Free-Hot-Air-Solder-Level or Lead-Free-Hot-Air-Level is similar to HASL in appearance and usage; however, the solder in this case contains a mix of 99.3% Tin and 0.6% Copper.
LPI – (Liquid Photo-Imageable Solder Mask): An ink that is developed off using photographic imaging techniques to control deposition. It is the most accurate method of mask application and results in a thinner mask than dry film solder mask. It is often preferred for dense SMT. Application can be spray, curtain coat or squeegee.
Laser Photoplotter: Alternatively called a laser plotter, this type of photoplotter creates a finely-lined raster image of the end product. The result is a high-quality, highly accurate plot.
Layer-to-Layer Spacing: This is the distance between PCB layers. The lower the spacing, the more difficult the manufacturing process will be.
Lead: Another word for a terminal on a component.
Legend: This is a shorthand guide for marking component names and positions. Legends help ease the assembly and maintenance processes.
LPI: Shorthand for Liquid Photoimageable, an LPI is a liquid solder mask that is sprayed on a PCB. This method is more accurate, thinner than a dry film solder mask and more affordable.
Mask: A material applied to enable selective etching, plating, or the application of solder to a PCB. Also called solder mask or resist.
Mark: A term used to refer to a set of patterns for optical localization. Marks can be classified into PCB Marks and local Marks.
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.
Membrane Switch: A membrane switch is applied to the front of a finished PCB. It indicates functions of the PCB and components, such as key functions, indicators and other parts. The membrane also provides protection for the PCB in the form of waterproofing and humidity protection.
Metal Base/Core Printed Board: Metal core PCB refers to a type of PCB with a core material made of metal instead of plastic, resin or FR4 material.
Metal Foil: The plane of conductive material of a printed board from which circuits are formed. Metal foil is generally copper and is provided in sheets or rolls.
Micro-Sectioning: The preparation of a specimen of a material, or materials, 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 0.005" or less that connects layers of a multi-layer PCB. Often used to refer to any small geometry connection holes created by laser drilling.
Mil: A "mil" is another way to say a thousandth of an inch. It's also the equivalent of a "thou. "
mm: "mm" is another way to express a millimeter or a thousandth of a meter.
Motherboard: This is the main board in a computer or electric device. The motherboard carries key interconnections and components that support the primary functions of the device.
Mounting Hole: This hole is intended to secure the PCB to its final location in a device. To ensure there is no interference, all mounting holes are non-conductive and unplated.
Multi-Layer PCB: This is a type of PCB with at least three conductive layers of trace and components.
Multimeter: A testing tool used to measure electrical values like current, resistance and voltage.
Multi-Wiring Printed Board: An equivalent to a multi-layer printed circuit board, this term refers to PCBs with multiple layers of trace, with dielectric layers between each.
NC Drill: This is a more common name for a Numeric Control drill machine. This type of machine is what assemblers use to drill holes in PCBs.
Negative: A reverse-image copy of a positive, useful for checking revisions of a PCB and is often used for representing inner layer planes. When a negative image is used for an inner-layer it would typically have clearances (solid circles) and thermals(segmented donuts) that either isolate holes from the plane or make thermally relieved connections respectively.
Net: A collection of terminals all of which are, or must be, connected electrically. Also known as signal.
Netlist: List of names of symbols or parts and their connection points which are logically connected in each net of a circuit. A netlist can be captured from properly prepared schematic-drawing files of an electrical CAE application.
Nomenclature: Identification symbols applied to the board by means of screen printing, inkjetting, or laser processes. See Legend.
Node: This is a pin or lead that is connected to at least one wire.
NPTH: An acronym for non-plated through hole, NPTH refers to a hole with no plated copper on the hole wall. This means no electric connections can be made using the walls of this hole.
Open: This is a short way of saying "open circuit, " which is a break in an electrical circuit's continuity. This prevents current from flowing and can disrupt the proper function of a PCB.
Outer-Layer: The top and bottom sides of any type of circuit board.
Pad: This is one of the most basic composition units of a PCB assembly. A pad is a contact point used to connect components with a via and is the point to which the components are soldered.
Panel: A panel is a combination of boards produced simultaneously to improve efficiency during the manufacturing process. Once the process is finished, these panels are typically broken apart into their singular units before being used.
Pattern: The configuration of conductive and nonconductive materials on a panel or printed board. Also, the circuit configuration on related tools, drawing, and masters.
Pattern Plating: The selective plating of a conductive pattern.
Panelize: This is the act of grouping multiple PCBs into a panel to improve manufacturing efficiency. An alternative term is panelization.
Part Number: This is an identification method used in industry to differentiate parts from one another. It's also used to identify specific parts, which is helpful in identifying problematic assembly batches and preventing incorrect product applications.
Part: This is another word for a component, or a basic piece of electric equipment, such as a resistor, capacitor, potentiometer, valve, radiator, etc.
PCB Array: Boards supplied in pallet form, sometimes called "panelized", "stepped out", "palletized" and "rout and retain
PCB Prototype: A printed circuit board fabricated especially for use in testing. In some cases, a printed circuit board manufactured rapidly for a specific application.
PCB Base Material: The material upon which the PCB is built. The PCB base material is typically composed of resin, metal, ceramic or another material with thermal and electric properties that support the PCB's final function.
PCB Database: All the data that is or could be used for a PCB design. This data is usually stored in a computer file.
PCB: An abbreviation of Printed Circuit Board, a PCB is a board that contains a conductive material and components, which act in synchrony to produce a designed response. PCBs rely on electrical circuits, which are either printed or soldered onto the board to elicit the desired result. Printed circuit boards are available in a wide variety of shapes, sizes and purposes to suit any industry or application.
PCBA: This is an acronym for Printed Circuit Board Assembly, where a company solders components to boards.
Peelable Solder Mask: A solder mask or layer of solder mask that can be peeled from the board.
Photoplotter: A device used in manufacturing to produce artwork onto film by plotting objects instead of images.
Photo Resist: A material that is sensitive to portions of the light spectrum and that, when properly exposed can mask portions of a base metal with a high degree of integrity.
Phototool: A transparent film that contains the circuit pattern, which is represented by a series of lines of dots at a high resolution.
Pick-And-Place: A method of SMT assembly where a machine automatically picks up SMDs and places them in the correct positions on the board.
Pin: A terminal on a component. It is also called a lead.
Pitch: The distance between pin centers of SMDs.
Plating: The chemical or electrochemical deposited metal on a surface.
Plated-Through Hole: Alternatively called a PTH, this is a procedure in which a through-hole is plated so that the hole wall can be conductive. This is often used as a contact point for through-hole components and can be used as a via.
Positive: A developed image of photo-plotted file, where the areas selectively exposed by the photo plotter appear black and unexposed areas are clear. For outer-layers, color will indicate copper. Positive inner-layers will have clear areas to indicate copper.
Prepreg: Also called PP, is the key material for multi-layer PCB manufacturing. it is primarily composed of resin and strengthening material that is then classified into glass-fiber cloth, paper base, compound material etc.
Press Fit Holes: This is a hole through which a contact terminal can be pressed into a PCB.
Printed Wiring: A process where a design is etched into conductive metal on a board, producing a wire design for the PCB.
Probe Test: A spring-loaded metal device used to make electrical contact between test equipment and the unit under test.
Printing: Part of the PCB manufacturing process where a circuit pattern is printed on the board.
Pulse Plating: A method of plating that uses pulses instead of a direct current.
PWB: An acronym for Printed Wiring Board, which is another name for a PCB.
Quick Turn: Fast turnaround PCB manufacturing. As a leading printed circuit board manufacturer in the USA, Advanced Circuits provides rapid PCB manufacturing and assembly services.
Reference Designator: Alternatively called "Ref Des, " this is the name of a component on a PCB. Typically, the component name begins with a letter or two, indicating the component class, followed by a number. These designators are usually printed on the silkscreen to help identify each component.
Reference Dimension: A dimension without a tolerance that is used only for informational purposes that does not govern inspection or other manufacturing operations.
Resist: A coating material that is used to mask or protect select areas of a pattern during manufacturing or testing from the action of an etchant, plating, solder, etc.
Reflow: This is the process of melting solder to create a joint between a pad and a component or lead.
RF: Short for radio frequency, RF is an electromagnetic frequency ranging between 300KHz and 300GHz. RF can also be a type of high-frequency electromagnetic signal.
RoHS: Alternatively known as the Restriction of Hazardous Substances, RoHS is a European environmental protection law. Many global companies must follow RoHS standards to sell products in the EU.
Rout: A layout or wiring of a connection. The action of creating such a wiring. The term is also used for the actual milling of a PCB.
Route/Track: This is the layout of a PCB's wiring structure, which is important for the proper function of the PCB. As a verb, the act of routing means designing such wiring structures.
Schematic: A technical drawing that illustrates the connections between PCB components. Schematics will often include abstract representations of components instead of pictures and is an important first step in PCB design.
Scoring: A technique in which grooves are machined on opposite sides of a panel to a depth that permits individual boards to be separated from the panel after component assembly.
Screen Printing: A process for transferring an image to a surface by forcing suitable media through a stencil screen with a squeegee.
Short: This is an alternative way to say "short circuit, " which is a connection with low resistance, resulting in excess current at the connecting point. This can cause serious problems in the PCB, including failure.
Silkscreen: This is a layer of epoxy ink applied to a PCB that contains component names and positions. The labels included on silkscreens help to direct workers through the assembly process. Typically, silkscreens are white, which helps the labels stand out against the PCB's solder mask.
Single-Sided PCB: A PCB design with traces and pads included on only one side of the board.
Slot Hole: Non-round holes on a PCB that may or may not be plated. These are often required for specific components but are costly due to the labor needed to cut them.
SMOBC –(Solder Mask Over Bare Copper): A method of fabricating a printed circuit board that results in final metallization being copper 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 mask.
SMD: Short for surface mount devices, it refers to components designed to be soldered on the surface of PCBs, rather than through a thru-hole.
SMT: Short for surface mount technology, this type of assembly technology directly solders SMDs to the surface of a PCB, rather than running components through thru-holes. This allows the board to function without drilling holes through it and also helps improve component density on the surface of the PCB.
Solder: An alloy that melts at relatively low temperatures and is used to join or seal metals with higher melting points.
Solder Coat: A layer of solder that is applied directly from a molten solder bath to a conductive pattern.
Solder Leveling: The process by which the board is exposed to hot oil or hot air to remove excess solder from holes and lands.
Solder Paste Stencils: Stencils ensure the right amount of solder paste is applied to achieve optimal electrical connections.
Solder Mask/Solder Resist: This is a layer of material, usually consisting of an epoxy resin, which isn't compatible with solder. This material is applied to the entire PCB, except those areas where content needs to be soldered. This process helps to physically and electrically insulate traces, preventing shorts. Solder masks are often green in color, though red and black are also common.
Solder Side: This is the opposite of the component side and is usually regarded as the bottom side.
Spacing: This term refers to the distance between wires on a PCB.
Step–and–Repeat: The successive exposure of a single image on order to produce a multiple-image production master. Also used in CNC programs.
Sub–Panel: A group of printed circuits arrayed in a panel and handled by both the board house and the assembly house as though it were a single printed wiring board. The sub-panel is usually prepared at the board house by routing most of the material separating individual modules leaving small tabs.
Surface Mount: Surface mount technology. Components are soldered to the board without using holes. The result is higher component density, allowing smaller PWBs. Abbreviated SMT.
Substrate: This is another word for "PCB base material", the primary material for PCB fabrication. Generally, this material can be flexible or rigid and can be made of epoxy, metal, ceramic or other materials. The function of the end PCB will usually determine which substrate will be used for the project.
Supported Hole: This is a via with pads on both sides of the PCB. It's also plated inside the via. This means the entire hole can support functions relating to thermal or electrical conductivity.
Surface Finish: Since copper tends to oxidize in natural environments, a surface finish protects the layer from doing so. Oxidation can cause the tin paste to fail or solder incorrectly. The primary types of surface finishes include HASL, ENIG, IMAG, OSP and others.
Tented Via: This is a type of via that has a dry film solder mask covering both its pad and its plated-thru hole. This solder mask insulates the via completely, protecting the PCB against shorts. Some vias are tented only on one side to allow for testing on the other.
Tenting: The covering of holes in a printed board and the surrounding conductive pattern with a dry film resist.
Terminal: A point of connection for two or more conductors in an electrical circuit; one of the conductors is usually an electrical contact or lead of a component.
Test Board: A printed board that is deemed to be suitable for determining the acceptability of a group of boards that were. Or will be, produced with the same fabrication process.
Test Fixture: A device that interfaces between test equipment and the unit under test.
TG: Glass transition temperature. The point at which rising temperatures cause resin inside the solid base laminate to start to exhibit soft, plastic-like symptoms. This is expressed in degrees Celsius (°C).
Thou: This is shorthand for a thousandth of an inch. It's another way to say "mil. "
Through-Hole/Thru-Hole: This refers to a hole passing through at least two layers of a multi-layer PCB. It's also used as a descriptor for components with parts or pins that run through a board to be soldered to another side.
Trace/Track: This refers to the copper path printed on a PCB. It functions similarly to an electrical wire, connecting components on a PCB board. The word "trace" is also used to refer to a segment of the path.
Tracing: This term refers to the width of a PCB's wires.
UL: UL stands for Underwriter's Laboratories, Inc., a renowned company specializing in establishing safety standards and independently assessing products according to these standards.
Unsupported Hole: This type of hole has a pad on the solder side, but no pad on the component side. There is also no metal layer inside the hole. This means the hole has no conductive reinforcement.
Vector Photoplotter: Alternatively called a vector plotter or Gerber Photoplotter, this type of photoplotter draws a plot line by line using light manipulation technology. This method can produce larger plots, but it is also much slower than the more modern laser photoplotter method.
Via: This term refers to plated through-holes that connect signals between traces on different layers of a PCB. These holes have conductive copper interiors to maintain an electrical connection.
Via Filled With Resin/Via Plugged: This is a via that is filled with an epoxy resin. Once filled, copper can be soldered to the surface of the resin without influencing the final product.
Via in Pad: Also called a thru-hole on the pad, a via in pad functions as an electric connection between layers. It is useful for multi-layer components or for fixing the positions of components.
Void: The absence of any substances in a localized area. (Ex: missing plating in a hole)
V-Scoring: This is an incomplete cut through a panel, which is often used to help break apart panels of PCBs into single units.
Wave Soldering: Assembled printed boards are brought in contact with a continuously flowing and circulating mass of solder, typically in a bath to connect the leads of components to through hole pads and barrels.
Wicking: Migration of copper salts into the glass fibers of the insulating material found in the barrel of a plated hole.
Wire: This refers to a conductive cable that can transmit electricity or heat. It also refers to a route or track on a printed circuit board.
X-Axis: The horizontal or left-to-right direction in a two-dimensional system of coordinates.
Y-Axis: The vertical or bottom-to-top direction in a two-dimensional system of coordinates.
Z-Axis: The axis perpendicular to the plane formed by the X and Y datum reference. This axis usually represents the thickness of the boards.
