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Glossary 

 

If you can not find in our glossary a definition for your subjects (contains meanings which apply to PCB design and manufacturing only) please dont hesitate to send us your query to: glossary@ellwest-pcb.com.

 

 

 

 

 

A

Ag. Chemical symbol for element silver.

Air Gap - The shortest straight line air distance between two conductors under voltage.

Annular Ring - The pad area that remains after a hole is drilled trough the  pad .

Analog circuit - A circuit in which the output varies as a continuous function of the Input.

ANSI - American National Standards Institute. WWW page: http://www.ansi.org .

AOI - Automatic Optical Inspection.

APERTURE - Aperture list or D-Code assignment are used in defining shapes and sizes of Gerber file entities.

ARRAY - A sub-panel which include the multiple printed circuits (called modules) so that the sub-panel can be assembled as a unit. The modules can then be separated after assembly into discrete printed circuits.

Aspect ratio -The ratio of the board thickness to the smallest-hole diameter of the printed circuit board

Assembly drawing - A drawing shows all parts identified by their reference designator,anel outline with datum and tooling hole position. If auto-insertion is required, a list of x, y coordinates of the parts may be helpful.

ATE - Automatic Test Equipment

Au - Chemical symbol for element  gold.

AQL - Acceptable Quality Level.

Axial Component - An electronic component consisting of two wire leads separated by a cylindrical component body, e.g., resistors, diodes, capacitors.

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B

Bare board - A finished PCB that has had no components added.

BASE MATERIAL - The insulating material upon which the conductor pattern may be formed. The base material may be rigid of flexible - It may be a dielectric sheet or insulated metal sheet.

B&B - Blind & Buried (VIA holes).

BBT - Bare Board Test.

BGA - Ball Grid Array. A leadless package on which the connectors to the board have been placed in an array on the bottom of the package.

Blind VIA - VIA hole that does not pass completely through the printed circuit board. A blind VIA starts from one side or another.

BOM - Bill Of Material. A component list with reference designators, part numbers, values, tolerance, description and other information. A BOM is required for PCB assembly.

BRIDGING(SHORT) - Solder that crosses the gap between two conductors, such as two leads.

Buried VIA - A buried VIA connects two or more inner layers but no outer layer, and cannot be seen from either side of the board.

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C

CAD - 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 PCB manufacturing  the result would be a printed circuit layout.

CAM - Computer Aided Manufacturing. CAM files - these are the data files used directly in the manufacture of printed wiring.

CARD - Another name for a printed circuit board. Card-edge Connector. A connector which is fabricated as an integral portion of a printed circuit board along part of its edge (see also finger).

CBGA - Ceramic Ball Grid Array.

CEM - Contract Electronic Manufacturers.

CERAMIC - Inorganic, nonmetallic material, such as alumina (a common substrate material composed of approximately 95% Al2O3) or beryllia (BeO 99,5. Beryllia has a high dielectric strength and a low dielectric constant) .

CHAMFER - A shaped corner to eliminate an otherwise sharp edge.

Characteristic Impedance - A compound measurement of the resistance, inductance, conductance and capacitance of a transmission line expressed in ohms.

CHIP - Non polarized surface mount capacitor, resistor or inductor with tinned conductive solder terminals at opposite ends of the part.

CLAD - A copper object on a printed circuit board.

Clearance - Separation between circuit entities ( pad-pad, pad-trace, trace-trace, solder mask-pad, pad-drill, circuit-board edge, etc.).

Coefficient of Thermal Expansion (CTE) - The ratio of dimensional change of an object to the original dimension when temperature changes.

COFIRE - A process for forming multilayer ceramic substrates in which thick-film conductors and dielectrics are simultaneously processed by a firing cycle.

Column Grid Array (CGA) - A packaging technology similar to a pin grid array, in which a device`s external connections are arranged as an array of conducting pins on the base of the package.

Compliant pin - The forces required for a good contact between pin and through hole are generated by the deformation of the press-fit section of the pin

COMPONENT - Any of the basic parts used in building electronic equipment, such as a IC, transistor, resistor, capacitor, connector, etc.

Conductor Spacing - The distance between tracks on a printed circuit board.

Conductor width - The observable width of the pertinent conductor at any point chosen at random on the printed circuit board.

CONNECTION - One leg of a net . Also called a "pin pair."

CONNECTOR - A plug or receptacle which can be easily joined to or separated from its mate.

Contact resistance - The resistance which occurs at the point of contact between a female contact and the male connector pin.

Controlled Impedance - The process that give a circuit the correct impedance value.

Copper foil - Quality electrolytic copper used to form conductive patterns on  printed circuits. The traditional weights are 0.5, 1 and 2 ounces per square foot (18, 35 and 70 micrometer thick)

Copper thickness - Cooper thickness usually specified in terms of number of Oz/sq. ft (1/2 Oz: 17.5um; 1 Oz: 35um and etc.). The thickness of copper you specified will be the final thickness of base material plus copper plating thickness.

CSP - Chip Size/Scale Packag.e

CTE - Coefficient of Thermal Expansion.

Cu - Chemical symbol for  element copper.

Cut lines - A cut line is what we are going to use to program a router with. It represents the outer dimensions of board.

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D

DFSM - Dry Film Solder Mask.

DIELECTRIC - An insulating medium which occupies the region between the conductors. It is also the distance between bonded inner layer conductors.

Dielectric Constant - That property of a dielectric that determines the electrostatic energy per unit volume for unit potential grade.

DIP - Dual In-line Package . A package designed for through hole mounting with parallel rows of evenly spaced leads extending straight down below the package at right angles to the top and bottom surfaces.

Drill File - Usually this is an Excellon  file (with X and Y  axis coordinates and tool sizes) used to create the hole of a  circuit board.

Drill Table - A description of the drill sizes used to create the circuit board. The drill equivalent of an aperture list.

Dry Film Solder Mask (Resist) - A solder mask film applied to a printed board with photographic methods. This method can manage the higher resolution required for fine line design and surface mount. It is more expensive than liquid photoimageable solder mask.

Dummy Component - A non-functional component package.

Dummy Land - A conductor on a printed circuit board that is not connected electrically to other circuitry.

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E

Edge Connector - A connector (can be gold plated) edge contacts or a series of parallel lines of holes.

Electrical Test - Used to test for opens and shorts. Recommended for all surface mount boards and multi-layers. Traditional test are done by test fixture with test pins wired to test system and compare connections/insulation read from board to board, an efficient type of test for volume production. Another type of test namely the flaying probes test, a set of 2 probes (or two sets, one set at top of board and another set at bottom), moving quickly to verify connectivity against the Netlist generated from Gerber or other CAD/CAM data.

Electroless Nickel Immersion Gold - A coating applied during printed circuit board manufacture to protect copper features from oxidation and provide a very flat surface for soldering components.

Electromagnetic Compatibility (EMC) - (1) The ability of electronic equipment to operate in an intended electromagnetic environment without degradation caused by interference. (2) The ability of equipment to operate in its electromagnetic environment without creating interference with other equipment.

ELECTROPLATING - The electrode position of a metal coating on a conductive object. The object to be plated is placed in an electrolyte and connected to the relative terminal of a DC voltage source. The metal to be deposited is similarly immersed and connected to the positive terminal. Ions of the metal provide transfer to metal as they make up the current flow between the electrodes.

Epoxy Resin - A material that forms straight chain thermoplastic and thermosetting resins.  Epoxy resins have excellent mechanical properties and good dimensional stability

ETCHING - The process of removing unwanted metallic substance (bounded to a base) via chemical, or chemical and electrolytic means.

Etch factor - The ratio of the depth of etch (conductor thickness) to the amount of lateral etch (undercut).

ESR - Electrostatically applied Solder Resist.

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F

Fiducial mark - Fiducial marks are dots etched on board panel for which SMD assembly is required (provide viewing targets for camera to locate correct position).

FILLET - Refers to the shape of the solder joint between the lead and the pad. Visual inspection criteria are largely based on the size and the shape of the fillet.

Fine pitch - Component with lead pitch equal to or greater than 20 and less than 50 mils; most common pitches are 20, 25, 33 mil.

FINGER - A terminal (usual gold plated) of a card-edge connector.

FIXTURE - A device that enables interfacing a printed circuit board with a spring-contact probe test pattern.

Flex circuit (Flexible circuit) - A printed circuit made of thin, flexible material.

FLUX - A substance used to promote or facilitate fusion, such as a material used to remove oxides from surfaces to be joined by soldering welding. Flux types: low residue, organic acid, rosin, rosin activated, rosin mildly activated.

FR4 - Flame retardant laminate made from woven glass fibre material impregnated with epoxy resin.

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G

Gerber File - Data file used to control a photoplotter. Named after Gerber Scientific Co., who made the original vector Photoplotter.

Gold Finger - The gold-plated terminal of a card-edge connector.

Ground Plane - A relatively large mass of metal on a printed circuit board used as an electrical ground or shield.

Grid Spacing - This is the spacing between drilled through holes in a printed circuit card.

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H

HDI - High Density Interconnection.

HTCC - High Temperature Cofired Ceramics

Hole breakout - A condition in which a hole is not completely surrounded by the land.

Hole density - The quantity of holes in a printed circuit board per unit area .

Hole void - A void in the metallic deposit of a plated - through hole exposing the base material.

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I

IEEE - Institute of Electrical and Electronic Engineers. IEEE Standards Board, New Jersey, USA. WWW page: http//www.ieee.org.

IEC - International Electrotechnical Commission is the leading global organization that prepares and publishes international standards for all electrical, electronic and related technologies. These serve as a basis for national standardization and as references when drafting international tenders and contracts. www-page : http://www.iec.ch

INCH - One inch = 25,4 mm.

INK - Common term for screen resist.

Insulation Resistance - Resistance of the insulating part between two conductors.

INTEGRATED CIRCUIT (IC) - An assembly of miniature electronic components simultaneously produced in batch processing, on or within a single substrate to perform an electronic circuit function.

Internal layer - A conductive pattern which is contained entirely within a multi-layer printed board.

Interstitial via hole - A plated through hole connecting two or more conductor layers of a multi-layer printed board but not extending fully through all of the layers of base material comprising the board.

IPC - .The Institute for Interconnecting and Packaging Electronic Circuits. WWW page: http://www.ipc.org .

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J

JUMPER - An electrical connection formed by wire between two points on a printed board added after the intended conductive pattern is formed.

L

LAND - A portion of a conductive pattern that is usually used for making electrical connections or for component attachment, or both.

LEAD - Metal attachment on a component used to mount the component to a printed circuit board and establish an electrical pathway.

LEGEND - A format of lettering or symbols on the printed  board : part number, component locations, and patterns.

Liquid Photoimageable Solder Mask (LPI) . A mask sprayed on using photographic imaging techniques to control deposition. It is the most accurate method of mask application and results in a thinner mask than dry film solder mask.

LTCC - Low Temperature Cofired Ceramics.

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M

MASTER DRAWING - A document that shows the dimensional limits or grid locations applicable to any or all parts of a printed board (rigid of flexible), including the arrangement of conductive and nonconductive patterns or elements.

Metal-Core PCB - Boards built with a metallic core and an organic or inorganic insulation on either sides of the core. The core could be made of steel, stainless steel, aluminum, copper, or a laminate of metals.

MIL - One thousandth of an inch.

Minimum Annular Ring (MAR) - The minimum metal width, at the narrowest point between the circumference of the hole and the outer circumference of the land.

Minimum Conductor Width - The smallest width of any conductors, such as traces, on a PCB.

Minimum Conductor Space - The smallest distance between any two adjacent conductors, such as traces, in a PCB.

Multi-layer PCB (ML) - Printed circuit boards consisting three or more conducting circuit plans separated by insulating material and bonded together with internal and external connections to of the circuitry as required.

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N

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.

NetList - List of names of symbols or parts and their connections points which are logically connected in each net of a circuit.

NFP - Non functional pad.

NFL - Non functional land. A land on internal or external layers, not connected to the conductive pattern on its layer.

Ni - Chemical symbol for the element nickel.

NPTH - Non plated-trough hole .

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O

OEM - Orginal Electronic Manufacturers.

OSP - Organic Solderable Preservative.

OVERHAND - Increase in printed circuit conductor width caused by plating build-up or by undercutting during etching.

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P

PAD (LAND) - The portion of the conductive pattern on printed circuits designed form the mounting or attachment of components.

PANEL - Material sized for fabrication of printed circuit boards. For example, standard panels by many Korean manufacturers are 340 x 407mm, 407x 510 mm, 510x 610 mm.

PANELIZE - 1.To lay up more than one (usually identical)printed circuits on a panel. Individual printed circuits on a panel need a margin between them of 3-7 mm. 2. Lay up multiple printed circuits (called modules) into a sub-panel (array) so that the sub-panel can be assembled as a unit. The modules can then be separated after assembly into discrete printed circuits.

PATTERN - The configuration of conductive and non-conductive materials on a panel or printed board. Also the circuit configuration on related tools, drawings, and masters.

Pb - Chemical symbol for element lead.

PCB - Printed circuit board.

Plated-through Hole (PTH) - 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.

Press-fit Connection - The press-fit connection which is made of elastic deformable or massive (solid) pins into the plated through holes of the PCB. At the point of contact between the pin and the through hole plating a gas tight connection ensues.

Press-fit Pin - A metal pin with a specified area for pressing into a plated through hole without the requirement of further soldering. There are two types of press-fit pins : solid and compliant pins.

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 or tin-lead alloy. The usual insulating material is epoxy laminate

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R

Radial Component - An electronic component with two or three wire leads emanating from the component body that is designed to stand up on the PCB by its leads, e.g., transistors, capacitors, hairpin axial components, etc.

REGISTRATION - The degree of conformity of the position of a pattern, or a portion thereof, with its intended position or with that of any other conductor layer of a board.

RESIST (Solder Resist) - A coating material that is used to mask or protect selected areas of a circuit board from etching or plating processes.

ROUTING - In PCB CAD layout application, routing refer to as making manual/automatic wiring connecting logical nodes in a net. In PCB fabrication, routing refers to board edges profiling by running N-C program.

RS-274-D - Photoplotter file format (a variant of Gerber data) requiring an additional aperture information file.

RS-274-X. - A variant of Gerber data which contains aperture shape information in addition to the usual tool selection and movement commands.

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S

Schematic Diagram - A drawing which shows, by means of graphic symbols, the electrical connections, components, and functions of an electronic circuit.

SCP - Single Chip Package

SHORT - Short circuit. An abnormal connection of relatively low resistance between two points of a circuit.

Silk-screen - The decals and reference designators in epoxy ink on a printed wiring board, so called because of the method of application - the ink is squeegeed through a silk screen.

SMC - Surface Mount Component.

SMD - Surface Mount Device.

SMT - Surface Mount Technology.

SMOBC - Solder mask over Bare Copper.

Sn - Chemical symbol for element tin.

SOLDER - Metal alloy used in soldering containing one of the metals used in the formation of an intermetallic bond.

Solder Balls - Small balls of solder that blow or roll across circuit boards causing shorts and other mischief.

Solder Levelling - The process of immersing printed circuit boards into hot liquids. Often referred to as HASL or HAL (hot air levelling)

Solder Mask - A coating applied over selected areas of a circuit board thereby permitting soldering only of the exposed areas : the contacts to be soldered; the gold-plated terminals of any card-edge connectors and fiducial marks.

Solder paste - Form of solder to be printed on SMD pads by using a stencil in assembly.

Solderability Testing - The evaluation of a metal to determine its ability to be wetted by solder.

Solid pin - The forces required for a solid mechanical contact between pin and hole are generated by the deformation of the drilled through hole.

SPAN - Component span refers to the center to center lead spacing of axial and radial components.

STENCIL - Stencil is a cooper foil screen with SMD pads etched openings use for solder paste printing in assembly.

Sub-panel - A group of printed circuits (called modules) arrayed in a panel and handled by both the board house and the assembly house as though it were a single printed wiring board. The sub-panel is usually prepared at the board house by routing most of the material separating individual modules, leaving small tabs.

SUPPORTED HOLE - A hole in a printed board that has its inside surface plated or otherwise reinforced.

SUPPORTING PLANE - A planar structure that is a part of a packaging and interconnecting structure to provide mechanical support, thermo-mechanical constraint, thermal conduction and/or electrical characteristics.

Surface Mount - Surface mount technology (SMT) - The technology of creating printed wiring wherein components are soldered to the board without using holes.

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T

TAB - Tape Automated Bonding.

Tented VIA - A VIA with dry film solder mask completely covering both its pad and its plated-through hole.

Test Coupon - An area of patterns on the same fabrication panel as the PCB, but separate from the electrical circuits and outside the actual board outline.

Tg - Glass transition temperature, temperature at which substrate changes from hard to soft.

Through-hole - Having pins designed to be inserted into holes and soldered to pads on a printed board.

Tooling Hole - A hole in a PCB that has close tolerances for hole diameter and accurate location in relation to the component insertion holes.

Tooling Pin - A pin on a workboard holder that holds the PCB in proper position by closely fitting into a tooling hole.

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U

UL - Underwriter`s Laboratories, Inc. - supported by some underwriters for the purpose of establishing safety standards on types of equipment or components. WWW page : http://www.ul.com .

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V

V-cut scoring - This is a V-shaped cut made between boards within an array.. This process is used when boards are placed side-by-side within the array with zero spacing between boards. After assembly the boards are snapped apart along the V-cut.

VIA - Feed-through. A plated-through hole in a PCB used to route a trace vertically in the board, that is, from one layer to another.  Common type of via connects traces on all layers, blind via or buried via are connected to defined layers only.

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W

Warping - Warping generally refer to finished board warp and twist. All boards may have certain degree of warp as result of manufacturing, specially if materials contains high volume of moisture.

Wet Solder Mask - Applied by means of distributing wet epoxy ink through a silk screen, a wet solder mask has a resolution suitable for single-track design, but is not accurate enough for fine-line design.

Wetting - Ability of a liquid to flow across a surface as opposed to sticking to itself. Wetting occurs when the attractive surface energy of the pad or lead is greater than the surface energy of the solder, drawing a molecularly thin layer of solder across itself.

Wicking - Ability of solder to travel towards a heat source or fill a through-hole.

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X

X Axis - The horizontal or left-to-right direction perpendicular to the Y axis in a two-dimensional system of coordinates.

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Y

Y Axis - The vertical direction, perpendicular to the X axis, in a two-dimensional system of coordinates.

 

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