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Glossary of terms

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Term Definition
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). Most packages have a regular outline, which makes them easy to handle automatically. The package contributes to the protection of the internal part against the environment, and its leads/bumps are the conductive interface between the internal component and the board. ‘Package’ is also used as a shorthand way of saying the format of a component, particularly integrated circuits. For examples, see DIP and SOIC.
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 electrical connection. Pads may also be used for test points. Also referred to as a land.
pad annulus   Typically refers to the width of the ring of metal around a hole in a pad.     
panel   Refers to the rectangular or square sheet of metal-clad base laminate from which boards are fabricated. A common panel size is 18in by 24in, of which 16.5 in by 22.5 in is available for printed circuitry. Where the panel contains a number of small circuit boards or boards with irregular outlines, as a means of standardising on board size to reduce the cost of product changeover, and to make the panel easy to handle, the term ‘panel’ is used to differentiate the original sheet from the individual circuit board(s) from which it is composed.
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   1) A component. 2) A decal in a database or drawing. 3) A symbol in a schematic.
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   The configuration of conductive and nonconductive materials on a panel or printed board. Also, the circuit configuration on related tools, drawing, and masters.
pattern plating   The 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-glass laminate material which has been etched to form a pattern of conductive traces. More correctly, but less usually, referred to as a ‘Printed Wiring Board’ (PWB). Especially within the computer industry, the term is also loosely applied to a board onto which semiconductor components are connected, although this is properly called a Printed Circuit Assembly (PCA).
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’.
PCMCIA   (Personal Computer Memory Card International Association). The name of the organisation (http://www.pcmcia.org/) that developed standards for PC cards in the 1990s, but often used for the standard formats themselves. The original document provided physical specifications for three types of cards using the same 68-pin connector, but other standards now cover smart cards, set-top boxes, and automotive applications.
PEC   Printed Electronic Component.
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.
photo print   The process of forming a circuit pattern image by hardening a photosensitive polymeric material by passing light through a photographic film.
photo resist   A material that is sensitive to portions of the light spectrum and that, when properly exposed can mask portions of a base metal with a high degree of integrity. See photoimageable resist.
photographic image   An image in a photo mask or in an emulsion that is on a film or plate.
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 board. Photoresists are either positive (areas exposed to light remain when the image is developed) or negative (areas exposed to light are removed when the image is developed).
photoplot data   Electronic data generated for use by photoplotting equipment.
photoplotter   Computer 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.
phototool   A transparent film that contains the circuit pattern, which is represented by a series of lines of dots at a high resolution. See artwork.
pick-and-place   A programmable machine, usually having a robot arm which picks up components from an automatic feeder, moves to a specified location on a PWB, and places or inserts the component onto or into the correct location.
pin   A terminal on a component, particular an integrated circuit part. The term applies equally to surface mount and through-hole components. The name is derived from the physical shape of some leads on older through-hole components. Also see lead.
pin count   The number of electrical contacts in a connector housing also called ‘number of ways’.
pinholes   Small holes occurring as imperfections that penetrate entirely through a layer of material.
pinless lamination  Lamination without pins is a method widely used around the world but generally limited to 4-layer boards. Pinless lamination is used by laminate suppliers in mass lamination production of laminate with built-in inner layers. Basically this method is based around 2 targets located at each end of the panel. These targets are incorporated on the 2 inner layer films so that they are imaged and etched as part of the inner layer circuitry. After lamination the outer copper on both sides is surface routed until the inner layer targets are exposed. These targets are then drilled through and the holes used for drilling location. A modified pinless lamination method can also be used to fabricate 6-layer boards. Drilling location holes are obtained in the same manner described previously. However, the major difference is registering the 2 inner layer cores which is achieved by riveting both cores using holes which are drilled after etching.
pin-out   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 will have a pin 1 and pin 2 for each resistor, even though the schematic might not show a pin number label as such. Childers comments that, for CAD/CAE electronics to work at all, the pin-outs for the PCB database must agree with the schematic.
pit   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).
pitch   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.
Plastic Leaded Chip Carrier   (PLCC). A component package with J-leads.
plastic stage   See pasty range.
plated through hole (PTH)   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.
plating   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.
plating void   The area of absence of specific metal from a specific cross-sectional area.
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.
polarization   A means provided by the shape of the mating connectors, which ensures that: a) The connector cannot be plugged together the wrong way round (that is,180° polarisation); b) Two similar size and shape connectors cannot be plugged into the wrong mating half.
pollution incidents:  Category 1: incidents having persistent and extensive impact on land, air or water. Category 2: incidents having significant impact on land, air or water. Category 3: incidents having minimal impact on land, air or water.
polyimide  (sometimes abbreviated PI) is a polymer of imide monomers. The structure of imide is as shown. Polyimides have been in mass production since 1955. Typical monomers include pyromellitic dianhydride and 4,4'-oxydianiline. Polyimide is the foundation laminate of most active flexible and rigid flexible PCBs.
positive   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.
postprocessing   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.
PQFP (Plastic Quad Flat Pack)   See QFP.
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.
preheat   The preheating stage of a process.
preheating   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.
prepreg   Sheet material (e.g., glass fabric) impregnated with a resin cured to an intermediate stage (B-stage).
press-fit   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.
pretinning   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.
pre-travel   The distance between the point where a connector starts to align when plugging together, and when electrical contact is made.
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 Board(PCB)   A flat plate or base of insulating material containing a pattern of conducting material. It becomes an electrical circuit when components are attached and soldered to it. The conducting material is commonly copper which has been coated with solder or plated with tin-lead alloy. The usual insulating material is epoxy laminate but there are many other kinds of materials used in more exotic technologies. Single sided boards have all conductors on one side of the board. With two-sided boards, the conductors, or copper traces, can travel from one side of the board to the other through plated-thru holes called vias, or feed throughs. In multilayer boards, the vias can connect to internal layers as well as either side.
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 contact  Makes electrical contact before others in the same connector (usually earths or power).
probe test   A spring-loaded metal device used to make electrical contact between test equipment and the unit under test.
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.
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.
PROM (Programmable Read-Only Memory)   See EPROM.
prototype   A pcb made and built to test a design.    
PTH   Has in the past referred to ‘pin-through-hole’ (that is, through-hole technology, the technology of mounting components by inserting them through boards), but now almost exclusively means 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, and not for lead insertion.
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.
pulse plating   A method of plating that uses pulses instead of a direct current.
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.