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


line certification
Assurance that a production line sequence is under management and will produce reliable PCBs in compliance with requirements.

liquidus
When heated, most alloys change gradually from being totally solid to being totally liquid over an extended temperature range. The liquidus is the temperature at which the alloy is totally liquid. Note that in the case of eutectic materials, there is no such pasty range See solidus and pasty range.

lithography
The transfer of a pattern or image from one medium to another, as from a mask to a wafer.

loads
(noun) Digital devices attached to a net that will have their logic levels changed by a driver on that net.

logic families
A group of device types that share the same basic operating characteristics and parameters when processing digital signals (TTL, ECL, etc.).

lot and date code
Items manufactured in a group using the same materials and processes are given the same, unique lot code. Items manufactured or completed on the same date are given the same date code.

Low Insertion Force
Refers to contacts, which, due to their design and function, require very little force to plug together. Used mainly in miniature and high pin count connectors.

Make Before Break (MBB)
Selected contacts in a connector that make an electrical circuit before breaking (open circuiting) other contacts.

male connectors
consist of an insulated plastic moulding (sometimes called a housing) fitted with plug contacts.

manual pin routing
See board routing process.

manufacturing data
Information consisting of photoplotting files, drill files, pick-and-place files, bare and loaded board testing files, support drawings, and bills of materials required to do the actual fabrication, assembly and test of a PCA.

manufacturing engineering
The technical organization that is usually responsible for planning and implementing PCA production activities.

markings
Information imprinted on parts and circuit boards, such as reference designations, part or serial numbers, revision level, orientation or polarization symbols, bar codes, and electrostatic discharge (ESD) sensitivity.

mask
A chrome and glass pattern for a layer of the wafer used in the photolithography process for silicon device manufacture.

mass soldering
The process of forming all solder joints on a PCA simultaneously (wave soldering, dip soldering, oven reflow, vapour phase soldering).

master artwork set
An accurately scaled, 1:1 pattern that is used as the source for producing working artwork films for circuit board fabrication.

master pattern drawing
A document that shows the dimensional limits or grid locations applicable to any or all parts of the circuit board. This also includes the arrangements of conductive and nonconductive patterns or elements, the size, type, and location of holes, and other information necessary to describe the product for fabrication.

material panel
Laminate, prepreg, and copper foil materials used for manufacturing circuit boards that are produced in standard sheet or panel sizes.

maximum-least material concept
Used in geometric dimensioning and tolerancing, maximum material describes the condition of a mechanical feature within a stated limit of size (minimum hole size, maximum shaft diameter). Least material describes the minimum size of a feature (maximum hole size, minimum shaft diameter).

MCM = Multi-Chip Module
A chip package within which more than one bare semiconductor die is bonded directly to a substrate by flip-chip, TAB or wire bonding. MCMs can also contain sealed components and chip components. The most complex are really encapsulated PCBs.

MCR = Moulded Carrier Ring
A type of fine-pitch package named from the method of supporting and protecting the leads. The leads are left straight, with their ends embedded in a strip of plastic, the ‘Moulded Carrier Ring`. The MCR is cut off, and the leads formed, only immediately before assembly, thus protecting them against handling damage.

measling
An internal defect in laminated base material in which the internal weave becomes visible, which takes the form of discrete white spots or crosses below the surface of the base laminate, reflecting a separation of glass fibres from the resin at weave intersections. Measling is usually due to thermally induced stress and indicates a weakened and un …

mechanical shock and vibration
External forces imposed on an assembly by cyclical energy inputs (vibration) or a single, sudden high-energy input (shock).

media
The type of material used for product data and documentation, such as electronic (tape, CD disk) and drawings (paper, Mylar, film).

megabit
One million binary pieces (bits) of information.

meniscus
That part of the insulation coating on a dipped component which has flowed up onto the lead, such as on a dipped capacitor.

metal foil
See copper foil.

metallisation
A metallic layer deposited on substrates and component terminations, either by itself or over a base metal, which makes it possible to create electrical and mechanical interconnections.

microstripline
A type of high-frequency transmission line configuration that has a specific, characteristic impedance value. It consists of a conductor placed in a precise relationship with a ground or reference plane and surrounded by dielectric materials.

microwave
Circuitry that operates at frequencies between 3 GHz and 300 GHz. See RF.

misregistration
Nonconformity of the position of a pattern (or a portion of the pattern), a hole, or other feature to its intended position on a printed board.

mixed analogue-digital
An integrated circuit or PCA that contains both analogue and digital circuitry.

mixed technology
When both through-hole and surface-mounting component types are used on the same assembly

modelling
A design analysis method using a software description of n item (electrical or mechanical) to simulate its operation in response to set of stimuli,

motherboard
A circuit board (or assembly) used for interconnecting a number of plug-in electronic modules (‘daughter boards`).

moulded-in contacts
Connector contacts that are encapsulated during the moulding process and cannot be removed. They are normally only used where a fully-sealed connector is required.

mounting hole
A hole used for mechanical mounting of a printed board (e.g. to the chassis) or for mechanical attachment of components to the board. (also known as an ‘access hole`)

MTBF = Mean Time Between Failures
The statistical average time interval, based on the probability of failure of a product, to be expected between operating unit failures. Usually quoted in hours.

multilayer (printed circuit board)
A PCB manufactured from (normally rigid) base material upon which completely processed printed wiring has been formed on more than two layers, each separated by insulating materials, and bonded together. Internal layers are connected to the outer layers by plated via holes.

multilayer lamination
See lamination.

multimeter
A portable test instrument which can be used to measure voltage, current, and resistance.

NC (Numeric Control) equipment
Any machine whose activity is commanded by instructions that are input to a programmable controller.

NC drill
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

NC drill file
A text file which tells an NC drill where to drill its holes.

NC fabrication equipment
Numerically controlled machine tools such as routers and drilling machines.

neck-down
The localized reduction of a conductor`s width to allow it to be routed through tightly spaced patterns.

negative
1) (adjective) Describing an artwork, artwork master, or production master in which the intended conductive pattern is transparent to light, and the areas to be free from conductive material are opaque.

net
An independent set of circuit nodes on a schematic that are connected together to define an isolated circuit. Each net is given a unique (alphanumeric) name to differentiate it from the other nets in the schematic.

net list
An alphanumeric listing of symbols or parts and their connection points which are logically connected in each net of a circuit. A net list can be ‘captured` (extracted electronically on a computer) from a properly prepared CAE schematic.

no-clean soldering
A soldering process that uses a specially formulated solder paste that does not require the residues to be cleaned after solder processing.

node
1) An electrical junction connecting two or more component terminations. 2) An individual component termination (pin), test point, or I/O within a circuit net. A ‘cluster describes a set of nodes which are connected directly by a track; an ‘open node` is a position at which a cluster may be accessed by a test probe.

nomenclature
The decals and reference designators in epoxy ink on a printed circuit board: see legend.

non-eutectic
Refers to an alloy which passes from a solid to a pasty state before passing to a fully liquid state during melt.

non-functional pad
A land on an internal or external layer that is not connected to an active conductive pattern on that layer.

non-recurring cost
The one-time (hopefully!) cost of design and development activities prior to starting production of a PCA.

non-wetting
A condition where a surface has contacted molten solder, but the solder has not adhered to all of the surface, so that some base metal remains exposed. Non-wetting is caused by a physical barrier (intermetallic or oxide) between the surfaces to be joined so that the wetting forces are insufficient to overcome the surface tension of the solder, res …

odd-form
The form or configuration of a non-standard component (such as transformers, coils, and large connectors) that may be difficult to handle by automatic placement equipment.

off-grid
Circuit board features that are not located on a grid intersection.

Omegameter
An instrument that measures ionic residues on PCBs by immersing an assembly into a water/alcohol mixture having a known high resistivity, and measuring and recording, over a specified period, the drop in resistivity resulting from ionic residues going into solution.

OMPAC
Motorola acronym for their OverMolded Plastic Array Carrier, a specific type of ball grid array component.

opacity
The level of transmissibility of light through a material. It refers to the ability to read markings covered by conformal coating or solder mask material on a PCA.

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

open entry socket
One where the entry for the mating plug contact is open such that the socket contact is vulnerable to damage if not mated correctly.

operating voltage
The nominal voltage that a circuit component needs in order to function properly.

operational environment
See environment.

optical alignment mark
See fiducial.

orientation marking
Information printed on a circuit board that provides component location information for the assembly of polarized or multi-leaded parts.

outgassing
Refers to gaseous emissions from solids or liquids, usually caused by exposure to high operating temperatures and/or altitude (low external pressure). Outgassing may come from absorbed gas, from the vaporisation of volatile contaminants, or from the breakdown of constituent materials. In a printed circuit board, outgassing may result in delaminati …

overlay
See inspection overlay.

overstressed
Material or component exposed to operating conditions beyond specified limits.

oxidation
A chemical process involving the combination of a material (usually a metal) with oxygen to produce a substance with substantially different physical and electrical characteristics from the base material.

oxide
Materials formed by the reaction of elements with oxygen. In the case of soldering materials, oxides are formed by reactions between the surface metals and oxygen in the air. This process is accelerated by high temperature. Oxides vary enormously in physical properties: some are flaky and poorly adherent, such as the oxides and hydroxides found in …

package
A generic term for a component which is protected from the environment in some way, usually by moulding in plastic. Packaged silicon devices contrast with the ‘naked die` used in the COB process. Packaged components can usually be tested fully before assembly (see KGD).

package I-O
Used for integrated circuit packages, refers to circuit terminations used for input and output purposes (as distinct from power connections) , and often associated with numbers, such as “32 I/O connections�.

package material
The type of material used for a specific type of electronic component (plastic, ceramic, metal).

packaging density
See high density interconnect.

pad
A discrete, identifiable portion of a conductive pattern on a printed circuit board, usually a square, rectangle or circle. Pads are generally connected to circuit traces, or vias underneath the pad, and are used for the electrical connection and mechanical attachment of components, but some may be purely for mechanical attachment, with no electri …

panel
Refers to the rectangular or square sheet of metal-clad base laminate from which boards are fabricated. A common panel size is 12in by 18in, of which 11in by 17in is available for printed circuitry.

panel plating
The process of electroplating copper on all conductive surfaces and holes of a circuit board. A circuit is defined by applying a resist pattern to the plated surfaces and etching away all copper not covered by resist.

panelisation
The placement of multiple patterns on a single panel, so that they may be processed simultaneously. Also used for the lay-up of multiple modules into a sub-panel, so that these can be assembled as a unit.

part footprint
A standard conductor land, and hole pattern that is unique to a specific type of component. It is used for mounting, soldering, and interconnecting those components on a circuit board.

part library
A structured catalogue of individual-component-part physical descriptions that contains all the information about each part needed during the layout of a circuit board.

partitioning
The allocation of functional circuitry to a PCA based on performance requirements and the physical space (‘real estate`) available for part placement and interconnection.

parts list
A tabulation of all parts and materials used in the construction of a PCA. See bill of material.

passive component
A part that exhibits a fixed or controlled value: and performs an elementary function in a circuit, such as a resistor, capacitor, inductor or conductor.

pasty range
As applied to soldering, denotes the semi-liquid state between liquidus and solidus as the solder begins to solidify, but is not yet completely solid, and conversely, when solder begins to melt but is not yet completely molten.

pattern plating
The process of electroplating metal only where a conductor is to be formed. A circuit is defined by applying a negative resist pattern to conductive surfaces and plating etch-resistant material in the openings in the resist. The resist is then removed and the unwanted copper etched away, leaving the conductor pattern

Pb
Chemical symbol for lead.

PCA = Printed Circuit Assembly
An assembly designed to perform a specific function, consisting of a printed circuit board to which separately manufactured electrical, electromechanical and mechanical component parts have been added.

PCB = Printed Circuit (Board)
The generic term for completely processed ‘printed wiring`, where predetermined conductive patterns are used to interconnect electronic components on a common insulating base. It includes single-sided, double-sided and multilayer boards made with rigid, flexible and rigid-flex materials, but the most usual PCB is a substrate of copper-clad epoxy-g …

PCB database
All of the data fundamental to a PCB design, stored as one or more files on a computer.

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`.

peel strength
The strength of the bond between copper foil and the base laminate to which it is attached.

PGA = Pin Grid Array
An IC package with a large number of connections which are made by through-hole pins arranged in a grid pattern on the bottom of the package. Precursor of the Ball Grid Array.

photoimageable resist
A photosensitive material available as a film or a liquid that is applied to the surface of a circuit board during fabrication. Collimated light passed through an artwork film defines an image in the material. Development of the material leaves an etch/plating-resistant pattern that is used to define the conductors on that surface of the circuit b …

photoplot data
Electronic data generated for use by photoplotting equipment.

photoplotter
C omputer controlled equipment used for generating an artwork image on a light sensitive emulsion coated on a stable material, usually plastic film. These artworks are generally the same size as the intended final pattern. See vector photoplotter and Gerber data.

photoplotting
A process that creates an image on a photosensitive material by a controlled light beam.

photoresist
See photoimageable resist.

phototools
See artwork.