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University of Bolton - Glossary of electronics terms
Category: Electronics and Engineering > Electronics
Date & country: 18/12/2007, UK
Words: 758


check plots
Pen plots that are suitable only for checking. Pads are represented as circles and thick traces as rectangular outlines instead of filled-in artwork. This technique is used to enhance the transparency of multiple layers.

chemical stability
The ability of the characteristics of a material to remain unchanged by aging or variations in the environment.

chip carrier
A low profile surface-mount component package, usually square, whose conductor chip cavity or mounting area is a large fraction of the package size and whose external connections are usually on all four sides of the package. It may be leaded or leadless.

chip component
Generic term for any two-terminal leadless box-shaped surface mount passive device, such as a resistor or capacitor. Also known as ‘discretes.`

chip on board
see COB

chip package
A carrier in which an IC chip is mounted. The package interconnects the chip to the outside world and is sealed to provide environmental protection for the chip.

circuit (circuitry)
The interconnection of a number of electrical elements and/or devices to perform a desired electrical function.

circuit coupling
The creation of a false signal in a circuit by a signal in another circuit. This is usually caused by radiated energy between adjacent conductors on the same or different layers.

circuit density
The proportion of circuit elements and interconnections required for performing an electrical function to the allotted area of a circuit board.

circuit fault
Incorrect performance of a circuit resulting in a specific error. In digital circuitry this could manifest itself as a logic error. During functional testing, artificial faults are sometimes injected into a circuit to verify the tester`s ability to identify them correctly.

circuit filter
Protective circuitry designed to prevent transmission of unwanted current or voltage deviations during operation.

circuit frequency
Usually pertains to the operating speed of a circuit and is a function of the types of components used, the dielectric properties of the circuit board( and the physical characteristics of the circuit conductors (dimensions/shape).

circuit net
See net.

circuit symbol
Used in a schematic diagram as a graphic representation of a specific type of electronic device.

circuit)
(USA ‘analog`) A type of circuit that deals with continuously varying voltage or current values that represent physical quantities, and where the output varies as a continuous function of the input, as contrasted with a digital circuit.

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.

cladding
A thin layer of metal foil bonded to a substrate to form the conductive PCB pattern.

clamshell fixture
An in-circuit test fixture that permits simultaneous probing of both sides of a board or assembly. The top probe section is hinged to allow board insertion.

cleanroom
The super-clean environment in which semiconductors are manufactured. The lower the rating (e.g. Class 100), the cleaner the facility. These rooms typically have hundreds of thousands of particles less per cubic metre than the normal environment.

Climate Change Levy
: A tax introduced on 1 April 2001, which is designed to stimulate business improvements in energy efficiency.

clinched lead
A component lead passed through a hole in the printed circuit board, that has been formed to prevent the component from falling out during soldering.

clinching
The process of forming or bending a component lead following its insertion through a hole in a circuit board. The main purpose is to secure the part mechanically during the soldering process.

clock speed
The switching frequency of the clock circuit in digital logic. It is principally determined by the rise/fall time required for the digital devices used in a circuit to change logic state (from 0 to 1 or vice versa).

closed bottom contact
The back of the contact is closed to prevent solder ingress, usually this applies to PCB and solder tail contacts.

closed entry socket
The entry for the mating plug contact is such as to prevent damage to the socket contact on insertion.

CMOS
Complementary Metal Oxide Semiconductor. A MOS device containing both N-channel and P-channel MOS active elements. One of two basic processes (MOS and bipolar) used to fabricate integrated circuits.

COB = Chip-On-Board
Generic term for any component assembly technology in which an unpackaged silicon die is mounted directly on the substrate, instead of first being packaged. Connections from die to the pads on the board can be made by wire bonding, tape automated bonding (TAB), or flip-chip bonding. For commercial use the die is protected by a plastic ‘glob top`, …

Coefficient of Thermal Expansion
See CTE.

cohesion
is the bulk (cross-sectional) strength of the adhesive material.

cohesive characteristics
See adhesive characteristics.

cold (solder) joint
A solder connection exhibiting poor wetting and of greyish, porous appearance due to insufficient heat or excessive impurities in the solder. The condition can be caused by applying insufficient heat to the joint, inadequately cleaning the surfaces prior to soldering, insufficiently heating the part being soldered, improper tinning of the solderin …

compliant press-fit terminations
are contacts in a connector where the tails are formed to have a compliant section. This section deforms as the tail is pressed down into the plated through hole of the printed circuit board. The inherent spring force in the compliant section retains contact during the life of the equipment without the need for a soldering operation.

component
A separate part of a printed board assembly which performs a circuit function. Active devices, such as resistors, capacitors, or semiconductors, have distinct electrical characteristics that perform specific functions in a circuit and with terminals which may be inserted into or mounted on, a printing wiring board to form a printed wiring assembly …

component hole
A hole used for attachment and electrical connection of component terminations, including pins and wires (‘leads`), to the printed board.

component lead
See lead.

component lead extension
The distance a through-hole component lead extends beyond the surface of a circuit board after soldering.

component library
A representation of components as decals, stored in a computer data file which can be accessed by a PCB CAD program.

component metallisation
see component termination.

component mounting orientation
The direction in which the components on a printed board or other assembly are lined up, with respect to one another, to the solder wave, and to the board.

component side
The primary side of a printed board upon which the major of component parts are mounted. Where size allows, the component side may be printed with the ‘legend`. (Also see ‘ topside`)

component termination
This term can refer to a lead, but is more commonly a description applied to the interface between the body of the component and the board in a leadless device. Termination materials need to adhere to the component, forming a reliable connection, and be wettable by (but not soluble in) the solder used for attachment to the board. Typically, for a …

Computer-Aided Design
A system where engineers create a design and see the proposed product in front of them on a graphics screen or in the form of a computer printout or plot. In electronics, the result would be a printed circuit layout. They may assist in performing all steps in artwork generation.

condensation soldering
A general term referring to a method of heating where an assembly is submerged into a hot, relatively oxygen-free, vapour. The vapour condenses on the relatively cool surface of the assembly, transferring its latent heat of vaporization to the parts being soldered. Also known as vapour phase soldering.

conduction
The ability of electrons to flow through a conductor. It is the reciprocal of resistance. Conduction is also a heat transfer mechanism in solid materials, involving transfer of kinetic energy within its molecular structure.

conductive adhesive
see anisotropic conductive adhesive and isotropic conductive adhesive.

conductive ink
The paste used on thick film materials to form the circuit pattern, usually containing metal, metal oxide and solvent.

conductor
A current-carrying interconnection path. A single conductive path in a conductive pattern. Also known as a ‘trace`.

conductor (conductive) pattern
The configuration or design of the conductive material on the base laminate, including conductors, lands, vias, heat-sinks and passive components when these are an integral part of the manufacturing process.

conductor layer
The total conductor pattern formed on one side of a single layer of laminate material.

conductor separation
Permanent separation of the printed wiring conductive foil from the base laminate. (Also see ‘ delamination`)

conductor side
The side of a printed board containing the conductors. Commonly referred to as the ‘solder side` when opposite through-hole components. (Also see ‘bottom side`)

configuration control
A method for ensuring that a specific version of data and drawings defines the correct requirements and physical description of the intended version of a PCA, and that the actual hardware conforms in all respects to the data and drawings.

conformal coating
An insulating protective coating applied to the completed board assembly, which conforms to the configuration of the objects coated and provides a barrier against deleterious effects of their environment.

connection
(US ‘connexion`) 1) Joining or linking to make an electrical contact to, or circuit with, the conductive pattern. 2) One leg of a net. Also called a ‘pin pair.`

connectivity
The intelligence inherent in PCB CAD software which maintains the correct connections between pins of components as defined by the schematic.

connector
A device that provides a mechanically pluggable interface for electrical terminations. 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.

constraining core substrate
A composite PCB consisting of epoxy-glass layers bound to a low thermal expansion core material, such as copper-invar-copper, graphite-epoxy and aramid fibre-epoxy. The core constrains the expansion of the outer layers to match the expansion coefficient of ceramic chip carriers.

contact bounce
Movement causing an open-circuit between a male and female connector contact or in a relay. This can occur due to vibration conditions during service, or during the plugging together operation of a connector.

contact carrying capacity
The maximum current a mating pair of contacts, or all contacts in a connector or relay simultaneously, can pass without causing degradation due to overheating and thermal stress. This is usually specified at room temperature and at maximum operating temperature, with a de-rating curve in between.

contact rating
The maximum and minimum voltage, current and power that a contact pair can be guaranteed to operate with under specified environmental conditions.

contact resistance
The resistance in the conductive path between two touching surfaces. It relates primarily to resistance across mating connector contacts.

contact retention
The specified force at which contacts will start to receive damage or pull out of a connector housing.

contact size
Defines the maximum wire size that can be used with a contact in a cable connector. This determines the contact diameter and current rating.

contaminant
An impurity or foreign substance whose presence on an assembly could electrolytically, chemically, or galvanically corrode the system.

continuity test
A test for the presence of current flow between two or more interconnected points.

controlled waste
: The UK term for wastes controlled under the Waste Framework Directive: any household, industrial or commercial waste.

convection
The mechanism for transfer of heat from a solid surface (such as a component) to a surrounding fluid (usually air). Natural convection is heat transfer to ‘still` air; forced convection involves heat transfer to air that is moved by artificial means such as a fan.

convection-IR
A solder reflow oven for SMD interconnect that combines convection and infrared (IR) radiation heating.

conveyor
A PCB transporting system for moving assemblies to various processes. An edge conveyor supports the boards at opposite sides; a mesh conveyor fully supports the board. On reflow ovens, a secondary mesh conveyor is often located below the edge mechanism to catch fallen components.

coplanarity
The leads of a package should be ‘coplanar with` the PWB, that is, there should be no gap between the leads and a flat board. If they are not, the non-coplanarity problem can result in open-circuit joints. The term coplanarity is however usually (somewhat incorrectly) used to refer to the maximum distance between the surface and the highest pin wh …

copper foil
See conductive foil.

copper weight
A measurement of the thickness of copper foil, in terms of its weight in ounces per square foot of surface area. 1-ounce copper is nominally 35µm (0.0014 in) thick, ½-ounce copper is 18µm (0.0007 in thick.

copper-clad dielectric material
The basic material used for fabricating a printed circuit board, consisting of a flat reinforced dielectric to which is bonded copper foil on one or both surfaces.

core
A supporting plane that is internal to a packaging and interconnecting structure. Multilayer circuit boards may contain unclad laminate cores, or special-purpose cores made of metal (aluminium, copper) to enhance heat dissipation or for other purposes.

corrosion
Gradual destruction of a metal or alloy due to chemical processes such as oxidation or the action of a chemical agent.

corrosive
A substance that causes corrosion; chemically reactive with ability to wear away gradually.

cost-benefit (trade-off) study
The analysis of the cost of implementing each of an alternative (design/manufacturing/assembly/test) approach (or solution to a problem) versus the benefits of doing so.

covers (or hoods)
Used on cable connectors to protect and insulate the terminations.

CPU
Central Processing Unit. The computer module in charge of retrieving, decoding, and executing instructions.

crazing
An internal condition existing in the laminate base material in the form of connected white spots or crosses on or below the surface of the base laminate, reflecting the separation of glass fibres from resin at the connecting weave intersections. Crazing is usually related to mechanically-induced stress. (Also see ‘ measling`)

critical signal paths
Conductors carrying signals that may be particularly sensitive to distortion by external signals, and require routing in specific locations on a board, or layout in a specific physical geometrical configuration.

cross-hatching
The breaking up of the large PWB conductor areas by the use of a pattern of voids.

crosstalk
See circuit coupling.

CSP = Chip-Scale Package
The Chip-Scale Package exists in many forms, often employing BGA and flip-chip elements. Regardless of the construction, the aim is to create a high-density IC package only slightly larger than the chip. A number of definitions have been proposed, of which the most usual is that the package should be no more than 1.5 times the chip in area and no …

CTE
(Coefficient of Thermal Expansion) The rate at which a material changes dimension as its temperature is increased. Can refer to the linear dimensions or the volume of the material. Expressed as the fractional change in dimension divided by the change in temperature, most commonly as ppm/°C. Often referred to as thermal coefficient of expansion (TC …

curing agent
A chemical added to a resin to stimulate a final set or hardening.

current rating
The maximum allowable continuous current that can be passed through a component or a conductor without causing degradation of performance.

cuts
Modification of a circuit board by separating conductors on an external layer to break a circuit connection.

dash number
Method for using part numbers to identify and control design modifications and interchangeability of assemblies. Using a root part number with different dash numbers indicates that variations of the same functional design exist.

data file
A collection of information organized in a specific manner for a specific application.

database
A collection of interrelated data items stored together without unnecessary redundancy, to serve one or more applications.

datum intersection (origin)
The point of intersection of the X and Y datums on a circuit board and the origin (0,0 point) of the layout grid. The 0, 0 point of a layout grid, usually located in the lower left corner of a board.

daughter board
A PCA attached to a mother board to provide additional and/or alternate electrical functions and capabilities.

DCA = Direct Chip Attach
See Chip-On-Board.

decal
A graphic software representation of a component, so named because hand tape-up of printed circuit boards employed the use of pull-off and paste decals to represent components. Also called a part, footprint or package. On a manufactured board the body of a footprint is an epoxy-ink outline.

decoupling capacitor
See bypass capacitor.

dedicated service product
Equipment or system that must perform reliably over long periods of time and experience minimum downtime, such as communication equipment, computers, and online instrumentation.

DEFRA
: Department for Environment, Food and Rural Affairs

delamination
A separation between plies within the base material, between the base material and the conductive foil, or both. Occurs both in PCBs and chip ceramic capacitors.

dendritic growth
Metallic filament growth between conductors in the presence of condensed moisture and electrical bias, threatening an electrical short. (Also known as ‘whiskers`)