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University of Bolton - Glossary of electronics terms
Category: Electronics and Engineering > Electronics
Date & country: 18/12/2007, UK
Words: 755

The assignment on a schematic of numbers (and names for more complicated packages) to specific device pins/leads. This gives a link between the electronic connections to a device and their physical counterparts in the package. Note that, even for devices with only two pins and no polarity, such as resistors, the net list extracted from a schematic …

Small holes occurring as imperfections that penetrate entirely through a layer of material.

A small hole (depression) occurring as an imperfection within a layer which does not penetrate entirely through the layer (as, for example, the conductive foil on a PWB).

The dimension between adjacent contacts along the axis of a connector housing, also known as ‘centre-to-centre distance`.

placement rate
The speed of a complete component placement cycle beginning with component/part pick-up, move to the placement site and return to the feeding source. Also referred to as Takt time.

plated (through-)hole
A drilled or punched hole through a substrate, which is metallised on the internal hole wall to make electrical connection between conductors on different circuit layers. See PTH.

plated through-hole
. This is a hole, in which metal is deposited on the wall of the hole after it is drilled, that can serve multiple functions: as an anchor to a component; as a conductive joint between the component and the circuits; as a connection between layers on a board. Vias, or via holes are small plated through-holes used only for interconnecting layers, an …

The process of the chemical or electrochemical deposition of metal on a surface, for example, of all or part of the conductive pattern. See electroplating and electroless plating.

PLCC = Plastic Leaded Chip Carrier
A surface-mounted component package with J-leads on four sides. PLCCs may be rectangular or square in shape and have a standard 1.27mm (0.05in) spacing between leads, so this package is not considered fine-pitch.

polarising slot
The slot, at the edge of a printed board, used to assure proper insertion and location in a mating connector. (Also referred to as the notch, keyway, or keying slot)

polarity marks
See orientation marking.

An artwork master or production master in which the intended conductive pattern is opaque to light, and the areas intended to be free from conductive material are transparent.

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

Conversion of layout information into data files having formats that can be used by equipment employed to fabricate, assemble, and test a PCA design.

power density
The distribution (or concentration) of power dissipation of electronic components and interconnections across the surface area of a PCA.

power plane
distributes power to circuitry on the board. Both ground and power planes may also be used as an electromagnetic shield and as a reference plane for high-frequency (stripline) circuitry.

PQFP = Plastic Quad Flat Pack
See QFP.

The distance between the point where a connector starts to align when plugging together, and when electrical contact is made.

precision artwork master
See artwork.

precision drilling
The process used to produce accurately located holes in a circuit board with closely held diametral tolerances.

precision turned contacts
Are manufactured by the screw machining process, and are basically therefore circular in format.

The preheating stage of a process, especially for wave soldering or reflow soldering.

Heating operation used to raise the temperature of the material above room temperature and thus reduce the thermal shock and influence the time for an elevated temperature process.

Sheet material (e.g., glass fabric) impregnated with a resin cured to an intermediate stage (B-stage).

Sometimes referred to as ‘compliant contacts`, these are pins that have a semi-spring area on the tails. When pushed into holes in the PCB, these will make and maintain electrical contact without the need for a subsequent soldering operation.

The process of applying a fresh coat of solder to component leads before mounting them on a circuit board. This is done to enhance solderability by removing/replacing oxidised material on the leads.

primary side
The side of a circuit board on which the most complex or highest number of components are mounted.

printed (edge board) contact
A portion of the conductive pattern which provides electrical connection by pressure contact. This is usually gold plated. (Also see gold finger)

printed circuit design
The process that depicts the printed wiring base material, the physical size and location of electronic components and mechanical parts, and the routing of conductors that electrically interconnect the components.

printed circuit fabrication
See board fab.

printed component
A part, such as an inductor, resistor, or capacitor (IC), which is formed as part of the conductive pattern of the printed board.

priority contacts
in a connector make electrical contact before others in the same connector (usually earths or power).

probing systems
Equipment for high-reliability testing of boards, components and assemblies. Probing devices range from manual for lab use to low-volume test via computer-controlled systems.

process mapping
: A logical step by step representation of business activities showing key inputs/outputs.

producer responsibility
: Requires industry and commerce involved in the manufacture, distribution and sale of particular goods to take greater responsibility for the disposal and/or recovery of those goods at the end of their useful life.

product life cycle
Encompasses fabrication, assembly, test, storage, transportation, and operation of a product.

production master
A one-to-one scale pattern derived from the artwork master, used to produce one or more printed boards within the accuracy specified on the master drawing.

pull-up and pull-down resistors
Resistive components that are used as terminations on transmission lines to reduce or eliminate signal reflections due to line discontinuities.

PWA = Printed Wiring Assembly
See Printed Circuit Assembly.

PWB = Printed Wiring Board
A general term for a fabricated substrate containing a defined interconnection pattern on which is to be mounted electronic components and mechanical hardware. More commonly known as a Printed Circuit Board or PCB.

QFP = Quad FlatPack
A generic term for rectangular or square surface-mounting packages with leads on all four sides. Most commonly used to describe packages with gull-wing leads. [Also known as a flatpack, but flatpacks may have gull-wing leads on two sides only] QFP lead pitches are fairly standard (typically 0.8mm; 0.65mm; 0.5mm; 0.4mm), but packages may have pin c …

radial lead
A component terminal that protrudes ray-like from the body of a component.

The mechanism for transfer of heat from a solid surface (such as a component) by electromagnetic transmission.

RAM = random access memory
A device that stores information, which can be both written and read many times. Any part of the memory can be accessed directly through an address. Data in RAM cells can be erased or changed by being overwritten or by removal of power from the device.

rat`s nest
A graphic display produced by a CAD system that shows all interconnections between circuit nodes on a layout as a set of straight lines (unrouted connections). [The name comes from the pattern of the lines as they crisscross the board, to form a seemingly haphazard and confusing mess similar to a rat`s nest] This display is useful when optimising …

: Using materials or products again, for the same or a different purpose, without material reprocessing (such as glass milk bottles or returnable plastic crates).

: Involves the recovery of value from waste, through recycling, composting or incineration with energy recovery.

recurring cost
The cost that is incurred for each item produced, including material and labour.

: Involves the reprocessing of wastes, either into the same material (closed-loop) or a different material (open-loop recycling). Commonly applied to non-hazardous wastes such as paper, glass, cardboard, plastics and metals. However, hazardous wastes (such as solvents) can also be recycled by specialist companies, or using in-house equipment.

: Reducing the quantity or the hazard of a waste produced from a process. It usually results in reduced raw material and energy demands â€` thus also reducing costs.

reference designator
An alphanumeric identifier assigned to each electronic component in a circuit. By convention this begins with one or two letters followed by a numeric value. The alpha part defines the type of component (R = resistor, C = capacitor, etc.) and the numeric part is a sequential number assigned to the component (R23 is the 23rd resistor used in the ci …

The undesirable return of signal energy due to a discontinuity in a transmission line in which the signal is travelling.

reflow soldering
A process of joining metallic surfaces (without melting the base metals) through the mass heating of pre-placed solder (usually in the form of paste) to create solder fillets in the metallised areas.

A printing term describing the proper positional alignment of artwork, tooling equipment and materials to ensure clear and accurate reproduction: used as ‘in register` and ‘off register`.

Properly register.

Material embedded in the resin of a laminate to provide additional mechanical strength. Typical materials are glass cloth, random glass fibres, paper, and a variety of high-strength plastic fibres.

The probability that an item will function under a specific set of conditions, for a stated period of time, without failure or unacceptable degradation of performance.

Restoring the functional capability of a defective component or assembly.

replaceable contacts
Can be replaced whilst in service by releasing them from their moulding and then the refitting of a new contact.

Excess of unwanted substances remaining after soldering, such as flux or oil.

A nonconductive plastic material, such as epoxy, polyester, or phenolic, used to produce printed circuit laminates.

Any material used to define a pattern by preventing the products associated with a manufacturing process from attacking (etching) or adhering (plating) to the surface covered by the resist.

revision number (or letter)
Sequential alphanumeric designators used on documentation and data to identify and control changes. The revision number or letter of a drawing should be advanced (A to B, etc.) any time the drawing is modified, to differentiate it from the previous version. In some companies, letters are used to denote designs not released for production, and numb …

Repetition of a manufacturing process to bring an assembly into compatibility with a spec or contract requirement.

RF = Radio Frequency
Also abbreviated rf, or r.f., RF is a term that refers to alternating current which will generate an electromagnetic field suitable for wireless broadcasting and/or communications.The RF spectrum is divided into several ranges, or bands. With the exception of the lowest-frequency segment, each band represents an order of magnitude increase in freq …

A term describing the viscosity and surface tension properties of solder pastes or adhesives.

ribbon cable
A multiple round conductor cable in flat ribbon format, which can be used in mass termination connectors. It is sometimes colour-coded.

A circuit board combining both rigid and flexible dielectric materials in a single assembly.

Short-term spikes in a signal. Usually related in digital circuitry to transients generated when a gate changes (switches) logic states.

The probability of the occurrence and potential negative impact of a decision or action on downstream activities.

RLP = registered land pattern
A specific component pattern geometry defined by the IPC that has been used and accepted as an industry standard for that type of part.

RMA = Rosin Mildly Activated Flux
- the most commonly used flux through 1995, but usually requires cleaning with CFC bearing materials so is being phased out.

ROM = Read-Only Memory
A device that is used for permanent storage of information. Data can be read many times, and remains when power is removed from the device.

root number
The portion of an assembly or part number that identifies its unique type or function (for PA123456-001, PA123456 is the root number)

rosin joints
A soldered joint in which one of the terminations is surrounded by an almost invisible film of insulating rosin, making the connection intermittently or continuously open even though it looks good. The interface has no metallic or electrical continuity which results in a high resistance condition with low strength.

A machining process for defining the outline of a circuit board which use cutters similar to end mills. See board profiling

1. n. A layout or wiring of a connection. 2. v. The action of creating such a wiring.

1) (Pronounced ‘rooting`) from route, establishing paths on a board for circuit interconnections. (Pronounced ‘rowting`) from rout, using a cutter to define the outline of a circuit board, as described under board profiling.

routing channel
The space available to route conductors between existing circuit features (pads, vias, holes, prerouted traces, etc.).

row spacing
The dimension between rows of electrical contacts across the axis of a connector housing.

rule class
A set of predetermined layout rules [spacing, voltage, conductor size(s), current, isolation, etc.] that are associated with a specific type or class of circuitry. For example, there may be a different rule class used on a layout for analogue circuitry than for digital circuitry on the same PCA.

See leaching.

schematic (diagram)
A diagram, drawing or plan which shows, by means of graphic symbols, the parts, electrical connections and functions of a specific circuit arrangement.

schematic symbology
A graphic diagram used to represent a specific type of component and its terminations on a schematic diagram.

To burn an exposed surface so as to change its colour or texture.

screen print
The decals and reference designators in epoxy ink on a printed circuit board, so called because of their method of application: see legend.

1) A process for transferring an image to a surface by forcing a viscous liquid material (such as ink, resist, or solder paste) through a screen with a squeegee. 2) The process of inspecting or testing a group of materials or parts to weed out noncompliant items.

secondary side
The side of the assembly that is commonly referred to as the ‘solder side` in through-hole technology. In SMT, the secondary side may be either reflow-soldered or wave-soldered.

selective plating
(sometimes called duplex plating) Connector contacts can be electroplated all over, usually with tin or gold. More common today are selective plating processes whereby gold is plated onto the mating contact area for optimum electrical performance and tin is plated onto the tail for solderability performance.

The tendency of components slightly misaligned during placement to self-align with respect to their land pattern during reflow soldering, due to the surface tension of molten solder. Minor self-alignment is possible but one should not count on it!

semi-aqueous cleaning
This cleaning technique involves a solvent cleaning step, hot water rinses and a drying cycle.

A solid crystalline substance whose electrical conductivity falls between that of a conductor and an insulator.

semiconductor device
An electronic component containing an active circuit material whose conductivity can be varied by a variety of external inputs (voltage, light energy, heat, etc.).

sequencing interconnections
Controlling the order of interconnection of nodes in a net during routing to enhance the performance of sensitive circuits.

A condition in which solder fails to wet the device leads during the wave-soldering process. Generally the trailing terminations of a component are affected, because the component body blocks the proper flow of solder. Requires proper component orientation to correct the problem.

shear strength
Ability of a solder joint to resist a force applied parallel to the printed circuit board.

An electrically conductive physical barrier designed to reduce the detrimental interaction of electromagnetic fields upon devices or circuits. Commonly attached to cables or connector housings to protect against EMI and mechanical damage. See EMI/EMC.

short (short circuit)
An abnormal connection of relatively low resistance between two points of a circuit. The result is excessive (often damaging) current between these points. At the design phase, such a connection is considered to have occurred in a CAD database or artwork whenever conductors from different nets either touch or come closer than the minimum spacing a …

shrouded contacts
Contained within the outline of the moulding, so preventing contact damage. Un-shrouded contacts protrude beyond the outline of the moulding.

1) A net. 2) A net other than a power or ground net.