This tutorial lists the terminology that is used in the wider Electronics Industry and therefore used in the DesignSpark PCB software
The glossary is arranged in an alphabetical order. Please click on a letter below or scroll down the page.
A¦ B¦ C¦ D¦ E¦ F¦ G¦ H¦ I¦ J¦ K¦ L¦ M¦ N¦ O¦ P¦ Q¦ R¦ S¦ T¦ U¦ V¦ W¦ Z
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Acid Trap - Describes an area in a PCB where the acid used in the manufacturing process cannot escape. This can cause problems of under-etching or over-etching.
Active Components - Semiconductor devices, such as transistors and diodes, that can change its basic characteristics in an powered electrical circuit, such as amplifiers and rectifiers. See also Passive Components.
Analogue Circuit - An electrical circuit that provides a continuous quantitative output as a response from its input. See also Digital Circuit.
Annotation - The adding of notes to a schematic.
Annular Ring - The width of the conductor pad surrounding a drilled hole.
Aperture - A description of the shape and size of the tool used to create a pad or track.
Aperture List - A list of the shapes and sizes for describing the pads and tracks used to create a layer of a circuit board.
Array - A group of elements that are arranged in rows and columns.
Artwork - Artwork for printed circuit design is photoplotted film (or merely the Gerber files used to drive the photoplotter), NC Drill file and documentation which are all used by a board house to manufacture a bare printed circuit board.
ASIC - Application Specific Integrated Circuit. Semiconductor circuits specifically designed to suit a customer's particular requirement, as opposed, for example, to a DRAM or micro-controller, which are general purpose parts.
ASCII - A basis of character sets used in almost all present day computers. US-ASCII uses only the lower seven bits (character points 0 to 127) to convey some control codes, space, numbers, most basic punctuation, and unaccented letters a-z and A-Z.
ATE - See Automatic Test Equipment.
Automated Test Equipment (ATE) - Equipment that automatically tests and analyses functional parameters to evaluate performance of the tested electronic devices.
Automatic Placement - A program that places components on the board depending on various factors such as length of connections and size of components.
Automatic Routing or Autorouter - A program that takes the connections paths between component pins and automatically places tracks in an orderly pattern. This automates what can be a time-consuming stage in the design of the PCB.
Axial leaded component - Axial leaded components are flat down type discrete components (i.e. resistors).
Back Annotation - The carrying back into the schematic from PCB of name changes that occur after the components are renumbered in the PCB, usually following placement.
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BGA - see Ball Grid Array.
Ball Grid Array (BGA) - A flip-chip type of package in which the internal die terminals form a grid style array, and are in contact with solder balls ( solder bumps ), which carry the electrical connection to the outside of the package. The PCB footprint will have round landing pads to which the solder balls will be soldered when the package and PCB are heated in a reflow oven.
BBT - Bare Board Test. The testing of an unpopulated PCB.
Bandolier - Components mounted in a double sided strip used for feeding Pick and Place machines.
Bare Board - An unpopulated PCB.
Bed of Nails - A test that contacts many points on a PCB to provide Automatic Test Equipment machines access to internal nodes of a PCB.
Bill of materials (BOM) - A comprehensive listing of all sub-assemblies, components, and raw materials that go into a parent assembly, showing the quantity of each required to make the assembly.
Bitmap - A rectangular set of pixels.
Blind via - A via extending from an interior layer to only one surface of a printed board.
Board - A printed circuit board.
Board Outline - The physical outline of the PCB. Is is formed from an unfilled closed space on a dedicated layer.
Board Profiling - Cutting a PCB board to the required shape.
BOM - see Bill of Materials.
Boundary Scan - An approach to the testing of printed circuit board assemblies that can be used to diagnose individual circuit failures by embedding the test circuits into the board and in the most failure prone integrated circuits.
Breakout - Describes poor registration between the hole and the pad on a printed circuit board such that the hole is not within the area of the pad.
Bridging - Where build-up of solder between tracks or pads causes a short circuit.
Buried via - A via that connects two or more interior layers of a printed circuit board and does not extend to either surface of the printed circuit board.
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CAD - Computer-Aided Design. The use of computer aids (hardware and software) in the electrical and physical design and verification of new things.
CAE - Computer-Aided Engineering. The use of computer aids (hardware and software) in electrical design.
CAM - Computer-Aided Manufacturing. The use of computer aids (hardware and software) in planning, tracking, analysing, and implementing the construction of manufactured items.
Capacitor - A two pin device providing electrical capacitance.
Capture - To draw (schematics) in such a way that data, especially connectivity, can be extracted electronically. Also see Schematic Capture.
Card - A printed circuit board of smaller dimensions is commonly referred to as a card. A card is generally one level lower than the printed circuit board in the hierarchy of packaging. A card is also referred to as a daughter board.
Card edge connector - A connector which is fabricated as an integral portion of a printed circuit board along part of its edge.
Ceramic Ball Grid Array (CBGA) - A ball grid array package with a ceramic substrate.
CERDIP - Ceramic Dual In-line Package. A package assembled with the leadframe sandwiched between two ceramic layers and sealed with a glass.
CERPACK - Ceramic Package. A CERDIP like package with the leadframe extended out on two or four sides, typically in surface-mounting format. Characteristics similar to CERDIP.
Chamfer - A corner that is shaped to remove an otherwise sharp edge.
Chip - The uncased and normally leadless form of an electronic component part, either passive or active, discrete or integrated.
Chip and wire - Assembly technique which uses discrete wires to interconnect backbonding die to lands, lead frames, etc.
Chip carrier - A low profile, usually square, surface mount component semiconductor package whose die cavity or die mounting area is a large fraction of the package size and whose external connections are usually on all four sides of the package.
Chip-on-Board (COB) - One of the many configurations in which a chip is directly bonded to a circuit board or substrate. These approaches include wirebonding, TAB, or solder interconnections, similar to the C4 structure. In low end consumer systems, Chip-on-Board generally refers to wirebonding of chips directly to board bonded and subsequently protected with a bit of resin material.
Chip Scale Package (CSP) - Chip scale package not much greater than the chip itself (typically not greater than 20% larger).
Circuit - The interconnections of electrical elements and devices that perform a desired electrical function.
Circuit Layer - A layer, on or within, a printed board containing conductors, including ground and voltage planes.
Clearance Rules - The required clearances between unconnected conducting structures on the PCB (for example track to pad).
CMOS - Complementary Metal Oxide Semiconductor. The primary technology in the design of Integrated circuits for digital circuitry.
Component - An element of equipment which unto itself does not form a complete system. Components can be integrated circuits, semiconductors, resistors, etc.
Component density - Quantity of components per unit area of printed circuit board.
Component lead - A wire or formed conductor that extends from a component and serves as a mechanical and/or electrical connection.
Component Side - The side of a PCB on which most of components are mounted.
Conductor, electrical - A class of materials -- usually metals -- that easily conducts electricity. Examples include silver, copper, gold, and super conducting ceramics.
Conductor, thermal - A class of materials, usually metals, that easily conduct heat. Examples include copper, aluminium, and beryllium.
Connectivity - The intelligence inherent in PCB CAD software which maintains the correct connections between pins of components as defined by the schematic.
Connector - A plug or receptacle which can be easily joined to or separated from its mate. Multiple contact connectors join two or more conductors with others in one mechanical assembly.
Coordinate - A position relative to an origin.
Conductor - Something that carries electricity with very little resistance. e.g. A Copper track on a PCB.
Connectors - A component mounted on a PCB that is used to provide electrical connection with external equipment.
Copper (Cu) - A metal used in semiconductor technology to form the interconnects between devices on a chip.
Copper Fill - Filling an area of a PCB with copper not directly needed for carrying a signal. This can provide for control of electrical noise (Susceptibility and emission), to provide a Heat Sink, and/or to prevent warping of the board.
Copper Pour - An enclosed area, usually defined by a polygon, flooded with copper, with solid/hatch pattern to create copper plane or section of copper plane. This is then connected to all instances of a given signal, usually O volts or 5 volts, by thermal relief pads. See also Thermal Relief.
Copper Sharing - Using a single section of track to carry a signal to more than one pin.
Crosshatch - Filling an area with two sets of parallel lines at an angle to one another.
Circuit - The interconnections of electrical elements and devices that perform a desired electrical function.
Cursor - The indicator on the screen.
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Daughter board - A PCB mounted, (piggy backed), onto another circuit board
Design entry - The process of creating a new design of any type chip, board, module, or system using schematic capture. Also referred to as design capture.
Design Rules Check - A program used to check the manufacturability of the circuit board. The checks include track to track gaps, track to pad gaps, track to board edge gaps, etc
Device - Any type of electrical component on a PC board. It will have functions and properties unique to its type
Digital Circuit - A circuit comprised of mostly integrated circuits which operates like a switch (i.e., it is either on or off).
Dielectric - Material that does not conduct electricity. Generally used for making capacitors, insulating conductors (as in crossover and multi-layered circuits) and for encapsulating circuits
DIL or DIP - Abbreviation for Dual In-line Package. A type of housing for integrated circuits. The standard form is a molded plastic container of varying lengths and 0.3 inch wide (although there are other standard widths), with two rows of through-hole pins spaced 0.1 inch between centres of adjacent pins
Diode - A two pin component conducting current in one direction only.
Dimension - To annotate a drawing or PCB with sizes, distances between critical positions.
Discrete Component - A component which has been fabricated prior to its installation (i.e., resistors, capacitors, diodes and transistors)
Double Sided - PCB assembly with components on both sides of the substrate but no inner layers. See also Single Sided and Multi-layer.
DRAM - Dynamic Random Access Memory
DRC - See Design Rules Check
Drill Table - A description of the drill sizes used to create the circuit board. The drill equivalent of an aperture list
Drilled Size - The size of the drill used to make a hole in a PCB
Dual-in-Line Package (DIP) - A package having two rows of leads extending at right angles from the base and having standard spacing between leads and between rows of leads. DIPs are made of ceramic (CERDIP) and plastic (PDIP)
DXF - Data Exchange Format originated for import/export of mechanical designs
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Earth - Another name for Ground
ECL - Emitter Coupled Logic - A type of unsaturated logic performed by emitter coupled transistors. Higher speeds may be achieved with ECL than are obtainable with standard logic circuits. ECL is costly, power hungry, and difficult to use, but it is four times faster than TTL
EDA - Electronic Design Automation: has largely taken the place of the term CAD in electronics, to cover all areas of electrical / electronic design and simulation using computer aids
Edge Connector - A connector on the circuit board edge in the form of gold plated pads or lines of coated holes used to connect other circuit board or electronic device
Edge Clearance - The smallest distance from any conductors or components to the edge of the PCB
EEPLD - Electrically Erasable Programmable Logic Device. A CMOS PLD made by using EEPROM technology. It can be erased and re-programmed
Effort - The resources applied to produce a suitable route. The higher the effort, the more resources router applies to routing the track. The lower the resources required, the shorter will be the time taken, and the neater the result.
Engineering Change Order (ECO) - A change in design
Embedded - Of a micro-processor(s), or system controlled by such) Dedicated to doing one job or supporting one device and built into the product
EMC - electro-magnetic compatibility - (1) The ability of electronic equipment to operate without degradation in an intended electro-magnetic environment (2) The ability of equipment to operate in its electro-magnetic environment without creating interference with other devices
EPROM - Erasable Programmable Read Only Memory. Can be erased and re-programmed
Etch - A process using a chemical bath (wet etch) or a plasma (dry etch) that removes unwanted substances from the wafer surface
Excellon - The de-facto standard for Computer Numerical Control CNC data for PCB drilling data originated for use with Excellon drilling equipment
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Fab - Short for fabrication
Failure - The temporary or permanent functional impairment of a component or device caused by physical, mechanical, chemical, or electrical damage
FC - Flexible Circuit, flexible circuitry
FET - Field Effect Transistor
Fibreglass - A common material for the Substrate of a PCB
Fiducial mark - Faducial marks are dots etched on board panel for which SMD assembly is required (provide viewing targets for camera to locate correct position)
Fillet - Applying a radius to an otherwise sharply angled edge
Fine Pitch - Fine pitch is more commonly referred to surface-mount components with a lead pitch of 25 mils or less Also, a general term for a PCB design where spacings of pads, tracks etc. is close to manufacturing limits
Fixed - Routes or tracks which may not be changed by the Router
Flash memory - Flash memory is a non-volatile memory device that retains its data when the power is removed. The device is similar to EPROM with the exception that it can be electrically erased, whereas an EPROM must be exposed to ultra-violet light to erase
Flat pack - An integrated circuit package with leads on two or four sides. The leads on these packages are either gull wing or flat, and have standard spacing. Packages with a lead pitch below 50 mils are referred to as fine pitch packages
Flex circuits - Flexible printed circuit boards made using thin polyimide or polyester film with copper circuitry on one or both sides of the flex. Flex circuits can be single or multi-layer
Flip - In PCB CAD context:- moving a component onto the opposite side of the PCB
Flip Chip - Unpackaged silicon dies that have been supplied with solder balls directly on the active side of the die. They are called flip chips because they are flipped upside down, compared to a conventional wirebonded chip
Flux - A chemically or physically active formulation capable of cleaning oxides and enabling wetting of metals with solder
Folder - A disk file, or the bottom level of a disk drive, that contains the names, dates, sizes, and filing system references to files and/or further folders. Also called a Directory
Footprint - The physical layout required for a PCB mounted component, including its pads and outline
Footprint Library - A ready built, or user built, selection of Component Footprints
Font, True Type - A Character or symbol Typeface designed to be easily scaled to different sizes
Forward Annotation - The process of applying the changes made to a schematic 'forward' to the PCB design. See also Backward Annotation
FPC - Flexible Printed Circuit, or flex circuit
FPGA, Field Programmable Gate Array - A type of logic device that allows its operation to be modified by means of on board programming
FR-4 - A NEMA grade of Flame-Retardent industrial laminate having a substrate of woven glass fabric and resin binder of epoxy. FR-4 is the most common dielectric material used in the construction of PCBs in the USA. Its dielectric constant is from 4.4 to 5.2 at below microwave frequencies. As frequency climbs over 1 GHz, the dielectric constant of FR-4 gradually drops
Free Pad - A pad not associated with a component. For example, a mounting hole.
Functional test - A test to verify product's behaviour after the components are mounted on board. Generally, functional test are performed as an alternative to in-circuit test in most application
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Gate - An part of the component representation. A component can be single-gate (one schematic symbol) or multi-gate (for example an Operational Amplifier IC in which each circuit is represented as a separate gate. Power supply can become yet another gate).
Gate Swapping - Exchanging pins in multi-gate packages, or between similar packages, to make routing easier
Gerber Data - A type of data that consists of graphics commands, usually describing how to draw a picture of a circuit. Intended for directing a photoplotter, it is the most common format for data transfer from PCB CAD systems to the manufacturing process
Glue Spot - What is used to hold Surface mount devices in placed on a bare PCB until soldering takes place
GND - See Ground
Grid - A two-dimensional network consisting of a set of equally spaced parallel lines superimposed upon another set of equally spaced parallel lines so that the lines of one set are perpendicular to the lines of the other
Ground - The nominal voltage reference, often called GND or 0V
Ground Plane - A conductive plane as a common ground reference in a multi-layer PCB for current returns of the circuit elements and shielding
Gull wing lead - A lead configuration, usually found on small outline packages, where the leads are bent. The end view of these packages resembles a gull in flight
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Hatch - The filling of an area with a set of parallel lines, Normal chosen to be horizontal, vertical or at 45 degrees
Heat sink - A structure, attached to or part of a semiconductor device that serves the purpose of dissipating heat to the surrounding environment; usually metallic. Some packages serve as heat sinks
Hertz or Hz - The unit for frequency of oscillation
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In-circuit test (ICT) - Combination of hardware and software that identifies manufacturing induced faults of printed circuit board assemblies (PCBAs) by isolating and individually testing devices using a bed-of-nails fixture. Potential faults include shorts, opens, wrong components, missing components, etc
Inner Layer - The layers of a circuit board that are sandwiched in between the outer layers. These may be tracking layers or plane layers
Insulators - A class of materials that do not conduct electricity and are characterised by high resistivity
Integrated Circuit (IC) - A miniature or micro-electronic device that integrates such elements as transistors, resistors, dielectrics and capacitors into an electrical circuit possessing a specific function. Form the basis of all modern electronic products
Interconnect - The conductive path required to achieve connection from one circuit element to another
I/O - Input/Output. Generally refers to the external connections of an IC that tie it to the outside world. Supply pins and control pins are usually not considered I/O
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J-lead - A lead configuration usually used on plastic chip carrier packages. J-leads are bent underneath the body of the package, with a side view resembling the shape of the letter "J"
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Kitting List - The list of parts needed to populate a bare PCB with components
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Laminate - A composite material made by bonding together several layers of same or different materials
Land - A portion of a conductive pattern that is usually used for making electrical connections or for component attachment, or both. See also Pad
Laser Photoplotter (also laser plotter) - A photoplotter which simulates a vector photoplotter by using software to create a raster image of the individual objects in a CAD database, then plotting the image as a series of lines of dots at very fine resolution. A laser photoplotter is capable of more accurate and consistent plots than a vector photoplotter
Laser soldering - A method of soldering in which the heat required to reflow a solder interconnection is provided by a laser
Layer - Is a side of copper foil. In a standard 2 layer board there are copper tracks and copper areas only on both sides of the laminate; 4 layer would mean there are 2 additional sides of copper track and copper areas "sandwiched" on internal layers between the exterior sides of the board. On more complex boards more layers may be sandwiched to improve the routability: 6 layer, 8 layer, and so on. Also see Multi-layer
Layer direction - Routers works most effectively when routes on a specific layer are biased to one axis. Routes requiring tracks in the different axis would be routed on another routing layer
LCC - Leadless Chip Carrier. A surface-mounted package having metallised contacts (terminals) at its periphery. Usually made of ceramic material
Lead - A wire that connects two points in a circuit; it is usually self-supporting
Leadless device - Electronic devices which do not have electrical leads extending from the body of the package. These packages could have solder bumps or lands located on the package
Lead pitch - The sum of the lead width and lead spacing. Typically stated as the distance between the centre of one lead to the centre of an adjacent lead
LED - Light Emitting Diode
Legend - Silk screened component identification marks or component outlines
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Manufacturability - A term defines the ability of meeting manufacturing requirements
MHz or Megahertz - a measurement of clock cycles in millions of cycles per second
Micro-controllers - Similar to micro-processor, but dealing with a simpler information set
Micro-processor - A standard circuit design that provides functions similar to central processing units by interpreting and executing instructions, usually incorporating arithmetic capabilities
Micron - A unit of measure equivalent to one millionth of a meter
Microvia - Small holes (0.002 - 0.004) that connect an outer layer of PCB to the nearest inner layers
Micro ball grid array - A fine pitch ball grid array. Fine pitch for BGAs is anything less than 1.27 mm
Mil - One thousands of an inch.
Mitre - Applying a straight edge at 45 degrees cut across an otherwise sharply angled 90 degree corner or edge. Quite common on PCB at right angled track junctions to improve manufacturability, reduce electrical reflections, and sometimes for purely cosmetic purpose
Misregistration - The lack of conformity between two or more patterns or features
Mixed Signal Products - Products that can process both digital and analog data
Mixed Technology - When pin through hole, surface mount, and other mounting technologies are processed on the same printed circuit board
MOS - Metal-Oxide-Semiconductor. Layers used to create a semiconductor circuit. A thin insulating layer of oxide is deposited on the surface of the wafer. Then a highly conductive layer of tungsten silicide is placed over the top of the oxide dielectric
Mother Board - Also called the Back Plane, or Matrix Board. A relatively large Printed Circuit Board on which modules, connectors, sub-assemblies or other Printed Circuit Boards are mounted and interconnections made by means of traces on the board
Multi Chip Module (MCM) - A module or package capable of supporting several chips in a single package
Multi-layered PCB - PCB layers are referred to as number of sides of copper foil used. PCBs with more than 2 sides of copper are defined as multi-layered, generally 4 layers, 6 layers and sometimes up to 16 layers
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NC drill or Numeric Control drill machine - A machine used to drill the holes in a printed board at exact locations, which are specified in a data file
Net - A line linking equipotential points in a design. It may branch, and form loops. Each net has a unique designation, and is linked to a net class which defines the style.
Net Class - Defines the minimum and nominal (desired) widths for a net when converted to a track by the Router
Netlist - A list of all the nets on a circuit board generated from a PCB's design data. This is known as a physical netlist in that it provides information on electrical connectivity between points on a board. This facilitates the testing of the PCB. This is distinguishable from the more general CAD sense of a netlist, which specifies component connectivity with no regard to actual physical locations of the points
Node - A pin or lead which will have at least one track connected to it
Non-plated-through - A type of holes on circuit board generally used as mounting holes
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ODB++ - A format for PCB manufacturing data developed by the Valor Corporation
Open - A circuit interruption that results in an incomplete path for the current flow. (e.g. an open wire which opens the path of the current)
Optimise - The re-organising of the connections too find the shortest length
Orthogonal Routing - A style of routing with horizontal and Vertical tracks
Origin - Some nominal starting point for a coordinate system
Output - A pin on a component that consistently drives the signal to a level determined by the component
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Package - 1) a printed circuit board component. 2) A type of PCB component which contains a chip and acts to make a convenient mechanism for protecting the chip while on the shelf and after attachment to a PCB
Packaging density - The quantity of components, interconnections, and mechanical devices per unit volume
Pad - A shape of copper used for mounting components
Padstack - A collection of the shape and size information of the subject pad
PAL - Programmable Array Logic. A device that can be programmed to do certain logic functions. Then a fuse inside of the device can be blown so the programmed information can never be changed. Sometimes called a PLD (Programmable Logic Device) Language
Panel - Material (most commonly an glass/epoxy-copper laminate known as core) sized for fabrication of printed circuit boards. Panels come in many, many sizes, the most common being 12 by 18 and 18 by 24. Subtract 1/2 to 1 margins (check with your board house) from the panel size to arrive at the space available for printed circuitry
Panelisation - A general term in CAM editing refers to step/repeat and other CAM editing to prepare data in panel format
Part - Component located by a manufacturers name or other unique identifier rather than the the logical or electrical function or package type identifier. A part may be a combined Schematic symbol and relevant footprints or, it can be just a schematic only part, or pcb footprint only part.
PBGA (Plastic ball grid array) - generic name for a BGA component constructed on organic substrate material, such as FR-4, overmolded with plastic
Parts List - A list of the parts required to build specific quantities of one or more PCB
Passive component - A device which does not add energy to the signal it passes. Examples: resistor, capacitor, inductor
PCB - see Printed Circuit Board
PCB design - 1) The creation of artwork for the manufacture of bare PCBs. 2) The artwork so created. 3. A computer database used to generate such artwork as data files ( CAM files ). Also called PCB layout
PCB designer - One who creates the artwork for printed circuit boards
PCB design bureau - A business engaged in PCB design as a service for others
PGA - See Pin Grid Array
Photoplotting or photoplot - Photoplotting is an electronic optical process to scan rasterised image data on films. Some times refer to as laser plotting
Photoplotter - A device for generating photographic images by directing a controlled light beam that directly exposes a light-sensitive material
Photoresist - A light sensitive liquid or a film, which when selectively exposed to light, masks off areas of the design that can then be etched away
Pick and Place - A manufacturing operation of assembly process in which components are selected and placed onto specific locations according to the assembly file of the circuit
Pin - a terminal on a through-hole component
Pin count - Number of pins any component, whether through-hole or SMT
Pin-Grid Array - A packaging technology for high pin count packages. Name derived from the array of pins at the bottom of the package. The pins go through holes in a printed circuit board. I/O lead counts as high as 600 can be achieved with PGA designs
Pin-out - Pin number assignment, the relation between the logical inputs and outputs of an electronic device and their physical counterparts in the PCB package
Pin Swapping - Exchanging signal connections to a device (with equivalent functions) so that routing is easier
Pitch - The centre to centre spacing between conductors, such as pads and pins. Pads for example of a 100 mils pitch will be spaced 100 mils between the pad centres. This can also be related to the pitch of screen grid dots
Pixel - Short for Picture Element, each 'dot' element of an image is a pixel
PLA - Programmable Logic Array. An array of logic elements that can be programmed to perform a specific logic function. It can be as simple as a gate or as complex as a ROM and can be programmed (often by mask programming) so that a given input combination produces a known output function
PLCC - Plastic Leaded Chip Carrier - An SMT chip package that is rectangular or square- shaped with leads on all four sides. The leads are spaced at 0.050 inches, so this package is not considered fine pitch
Placement - The arranging the components on a PCB to fit the required board outline
Placement, Automatic - See Automatic Placement
Plated-through hole - A hole in a PCB with metal plating added after it is drilled. Its purpose it to serve either as a contact point for a through-hole component or as a via
Polygon - An open or closed, non-intersecting figure formed from a continuous line on a single layer. One form of a 'Shape'. Closed polygons may be filled
Polyimide - A material used as a Substrate for a PCB
Populated board - A PCB with components
Powerplane - A layer of a multi-layer PCB that is used to provide an earth reference or Power feed. Connections to the plane may need to provide a Thermal Break
Powerplane, Split - A Powerplane that carries more than one power supply or ground on a single layer. As the name denotes this is split on the same layer
PQFP - Plastic Quad Flat Pack. A square, flat package with gullwing leads located around all four sides of the package
Programmable Logic Devices - Devices with 10-100 times higher level of integration than a TTL; called programmable because they can be customised in software rather than in hardware.
Printed circuit board (PCB) - A printed circuit board is a component carrier that contains etched copper patterns that connect the leads of one component to the leads of other components. PCBs are often composed of a glass fabric impregnated with a resin (usually epoxy), cured, and clad with metal (almost always copper) upon which a pattern of conductive traces is formed to interconnect components. PCBs can be rigid or flexible and composed of single, double, or multi layers
Printed circuit board assembly (PCBA) - Second level integration of active and passive devices (electrical, electronic, optical and/or mechanical) on a rigid substrate
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QFP - Quad Flat Pack, a fine pitch surface mount package that is rectangular or square with gull wing shaped leads on all four sides
QSOP - Quarter Size Small Outline Package. An SO style IC package that has leads on a 25 mil pitch. The name derives from the fact that the package is approximately half the length and half the width of a standard SOIC
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Radial Lead - A lead extending out the side of a component, rather than from the end. Radial leaded components are standing type discrete components; examples are disc capacitors and TO-92 type transistors
Rats-nest - A bunch of straight lines (unrouted connections) between pins which represents graphically the connectivity of a PCB CAD database. [Derived from the pattern of the lines: as they crisscross the board, the lines form a seemingly haphazard and confusing mess similar to a rat 's nest.
Reference designator - Component ID use in schematic and PCB, such as C1, C2, R1, R2, etc.
Reflow - The application of heat to a surface containing a thin deposit of a low melting point metal or alloy (e.g., solder paste tin lead alloy), resulting in the melting of the deposit, followed by its solidification
Reflow soldering - The process of joining metallic surfaces through the mass heating of solder/solder paste to form solder fillets at the metallised areas. Reflow soldering creates a mechanical and electrical connection between the components and the PCB
Registration - A term frequently used in the PCB industry. It refers to layer alignment of data, artwork, films, imaging process, screening, lamination, drilling, routing, etc
Resist - A coating material that is used to mask or protect selected areas of a circuit board from etching or plating processes
Resistor - A two pin component that nominally 'resists' electrical current flow in a linear manner
Route (or Track) - A layout or wiring of an electrical connection
Routing - The process of converting connections into tracks without crossing tracks, going outside the board area, entering disallowed areas, etc. This can be accomplished manually - i.e. by explicitly arranging signals interactively, or by using Automatic Routing
RS-274D - The basic specification of data for Gerber Photoplot output. See Gerber Data.
RS-274-X - A variant of Gerber data which contains aperture shape information in addition to the usual tool selection and movement commands. See Gerber Data.
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Schematic - A diagram which shows, by means of graphic symbols, the electrical connections, components and functions of an electrical system. The components are represented by agreed-upon symbols, and the conductors connecting them by lines
Schematic Capture - The capture of circuit design by graphical means. The symbols representing functional blocks or individual circuit elements and interconnected by graphical representations of wires, pins, etc
Screening - Providing an earthed, conducting box, outer sheath, or area of copper on a PCB to protect from external electrical interference, or from generating such interference
SDRAM - Synchronous Dynamic Random Access Memory
Semiconductor - Components that amplify, switch, or rectify electronic signals. These devices, also known as active components, include transistors, diodes, and integrated circuits
Short or Short circuit - An abnormal connection of relatively low resistance between two points of a circuit. The result is excess (often damaging) current between these points. Such a connection is considered to have occurred in a printed wiring CAD database or artwork anytime conductors from different nets either touch or come closer than the minimum spacing allowed for the design rules being use
Silkscreen - The decals and reference designators in epoxy ink on a printed wiring board, so called because of the method of application, the ink is squeezed through a silk screen, the same technique used in the printing of T-shirts
Signal - A Digital or Analogue voltage or current that passes between components. More casually, the pieces of track that join together 2 or more pins.
SIMM - Single In-line Memory Module: a high-density DRAM package alternative consisting of several components connected to a single printed circuit board
Simulation - The process of using software to model an electronic system
Single in Line - A component with all its pins in a single row
Single Sided Board - A printed circuit board that contains tracks and pads on one side of the board and no plating in the through holes
SMD - Surface Mount Device
SMT - Surface Mount Technology
SMSO or Surface Mount Small Outline - a standardised footprint
Small outline J-leaded (SOJ) - An integrated circuit surface mount package with two parallel rows of J-leads
Small outline transistor (SOT) - Discrete surface mount transistors with a molded plastic outline that serve small and medium power applications
SO or Small Outline - A package resembling a flat pack with leads on only two sides
SoC (System on Chip) - A single chip on which multiple specialised blocks of logic have been combined
SOIC - Small Outline Integrated Circuit. A plastic IC package for surface mounting applications that has leads on two opposite sides
SOP - Small Outline Package. Similar to SOIC
Solder - A low melting point alloy used in numerous joining applications in micro-electronics. The most common solders are lead-tin alloys. Typical solder contains 60% tin and 40% lead - increasing the proportion of lead results in a softer solder with a lower melting point, while decreasing the proportion of lead results in a harder solder with a higher melting point
Solder Mask - A coating applied over selected areas of a circuit board thereby permitting soldering only of the exposed (uncoated) areas, usually only the pads
Solder paste - Form of solder to be printed on SMD pads by using a stencil in assembly
Solder Resist also known as Solder Mask - A coating that during manufacturing prevents solder wetting undesirable areas
Solder Side - On printed circuit boards with components on only one side, solder side describes the side of the PCB that is opposite to the component side
Solder Wave - One technique for soldering Surface Mount and the primary technique for conventional components, is to arrange that a 'wave' of molten solder ripples along back side of the board. See also Solder Paste
SOIC or Small-Outline Integrated Circuit - A miniature plastic flat pack designed for surface mount with gullwing leads
SOP or Small Outline Package - Similar to a miniature plastic flat pack, but with gullwing leadforms primarily or wholly constructed for surface mounting
SPICE or Simulation Program with Integrated Circuit Emphasis - Simulator used to model electrical circuits at the transistor level
SSI (Small Scale Integration) - An integrated circuit (IC) having fewer than 100 elements
SSOIC - Shrink Small Outline IC. An SO style IC package that has leads on a 25 mil pitch
Step & Repeat - A process where the printed circuit board layout or component placement is repeated many times in evenly spaced rows
Stroke Font - A stroke font is made up of small 'drawn' line segments of a given width
Stripline - A technique to tightly control the Transmission Line characteristics of a PCB trace by running parallel tracks for signal and return path, or differential pair
Substrate - The base material of a PCB onto which the Copper tracks and subsequent coating (e.g. Solder Resist) are applied. Examples of these materials are Fibreglass, SRBP, FR4, CEM1, Polyimide, Duroid and Teflon. Specialist ceramic materials are often used for Hybrids
Surface Mount - See surface mount technology
Surface Mount Technology (SMT) - A method of assembling hybrid circuits and printed wiring boards where component parts are mounted onto, rather than into, the printed wiring boards, as in the mounting components on substrates in hybrid technology
Symbol - A graphical representation of a component that contains information about the ports of the component
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T-Junction - The point (in Schematic or a PCB Layout) where a connection is made to another by contacting it at some position along a line (as in the upright of a letter T contacting the top bar)
Teardrop Pad Shape - A basically circular Pad with one side stretched out to provide a connection point
Terminal - A point of connection for two or more conductors in an electrical circuit; one of the conductors is usually an electrical contact, lead or electrode of a component
Testing - A method for determining whether sub-assemblies, assemblies and/or a finished product conform to a set of parameter and functional specifications. Test types include: in-circuit, functional, system level, reliability, environmental
Test board - A printed circuit board deemed to be suitable for determining the acceptability of a group of boards produced with the same fabrication process
Test Point - A specific point in a circuit board used for specific testing for functional adjustment or quality test in the circuit based device
Test Strategy - Defining a test methodology for a given product that translates into test requirements and test development
Thermal Analysis - Estimating the thermal (temperature) performance of a design to determine whether changing layout would reduce 'hot spots'
Thermal Break - Used for improving soldering of holes connected to a powerplane
Thermal Relief - A wagon wheel shaped relief pad etched in the copper of a ground plain around a through hole. It connects to the plane through one or more narrow track across an opening in the plane, rather than connecting directly to the plane, so that heat transfer to the plane is minimised during soldering
Thermal Cutout - See Thermal Break
Through-hole - Refers to a component having pins designed to be inserted into holes and soldered to pads on a printed board. Contrasts with surface mount
Tooling hole - Manufacturing tooling holes are used for PCB fabrication, assembly and other test purposes. These holes serve the purpose of holding PCB panel to fixture during manufacturing
TQFP - Thin Quad Flat Pack. Essentially the same as a QFP except low profile, that is, thinner
Track - A copper 'line' on a PCB to conduct signal current
Track Clearance - The minimum permitted close approach to another signal
Transistor - A three terminal active semiconductor device that serves as a switch or provides current amplification. Comprised of a base, emitter, and collector (bipolar transistor) or gare, source, and drain electrodes (field effect transistor). Invented by Shockley (Bell Labs) in 1947
TrueType Font - These are fonts that may be scaled on the system jointly developed by Apple and Microsoft
TSOP - Thin Small Outline Package. It is thinner and slightly smaller than an SOJ and with gullwing shaped leads. A thin, rectangular package with leads sticking out the sides of the package
TTL - Transistor - Transistor Logic. Also called multiple emitter transistor logic. A widely used form of semiconductor logic
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Unfixed - Tracks and routes which the autorouter may edit when routing nets to improve the finished design
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Vapour phase reflow - A solder reflow technique in which the solder joints are heated by the condensation of an inert vapour
Vector Image - An image stored as a series of lines. The benefit being they can be scaled up and down without distortion.
Vector Photoplotter (also vector plotter, or Gerber photoplotter) - named after Gerber Scientific Co., which built the first vector photoplotters for commercial use)
Vcc - A name for a power net meaning voltage collector, usually +5V for TTL circuits
Via - A plated through hole used as a through hole connection between the layers on a circuit board. These holes are generally the smallest as no components are inserted in them
VSP or Vapour Phase Soldering - Soldering accomplished by using heat generated by the condensing of a vapour ion a cooler assembly.
VSOIC - Very Small Outline IC. An SO style IC package that has leads with a pitch of 30mils or less
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Warping - Warping generally refer to finished board warp and twist. All boards may have certain degree of warp as result of manufacturing
Wave Soldering - A manufacturing operation in which solder joints are soldered simultaneously using a wave of molten solder
Wire bonding - The method used to attach very fine wire to semiconductor components (dice) to interconnect these components with each other or with package leads
WYSIWYG - What You See Is What You Get
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Zero width - Zero width represents a outline shape drawn by thickness line width
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DesignSpark Team (RS Components/Allied Electronics)
