GGG logo SERVICES ADVANTAGE ABOUT ARTICLES BLOG
Golden Gate Graphics logo

GLOSSARY of Printed Circuits

by John Walt Childers, IPC-CID, Founder of Golden Gate Graphics

   A    B    C    D    E    F    G    H    I    J    K    L    M    N    O    P    Q    R    S    T    U    V    W    X    Y    Z   

Pronunciation Key

Golden Gate Graphics in an official Altium Service Bureau

Golden Gate Graphics is an official Altium Service Bureau

Terms that contain digits are alphabetized as if the numeric characters were spelled in English.

Terms with two or more words are alphabetized "dictionary style." They are alphabetized as though the spaces between the terms have been removed.
   If there are other characters in the term, such as a slash (/), these are treated the same as spaces and ignored for the purpose of alphabetizinig.



ablation — (u-BLAY-shən)  Pronunciation Key  noun  [PCB Manufacturing] (In the context of "laser ablation" in the making of blind and buried vias) Vaporization.
A PCB designer should be aware that a hole caused by ablation has an inverted cone shape rather than a cylindrical shape, as would be the case with a hole drilled with a bit. Partly because of this, a laser-ablated hole can not have an aspect ratio greater than 1:1. In contrast, a drilled hole can have an aspect ratio of 10:1 or greater (or less for some board houses). Therefore, laser-ablated holes are only feasible in build-up manufacturing. The padstack for a laser-ablated via can have a smaller pad on the tapered end than on the large (the starting point) end. This fact can be helpful in designing a space transformer.
A terms index



active component  — (AK-təv KOM-poh-nənt) Pronunciation Key

  1. noun [Electronics] A component which adds energy to the signal it passes.
        
  2.  
  3. noun [Electronics] A device that requires an external source of power to operate upon its input signal(s).
        
  4.  
  5. noun [Electronics] Any device that switches or amplifies by the application of low-level signals.
    Examples of active devices which fit one or more of the above definitions: transistors, rectifiers, diodes, amplifiers, oscillators, mechanical relays and almost all IC's (Contrast with passive component.)   
A terms index



active heatsink — (AK-iv HEET-seenk)  Pronunciation Key  noun  [Components] A heatsink which uses an applied energy to operate.
Examples are 1) a mini-fan attached to a chip package and 2) a TEC with a fan to blow away generated heat.
A terms index



AFE — (AY-EF-EE)  Pronunciation Key  noun  [Electrical Engineering] Analog Front End

A terms index



ALN — (AY-EL-IN)  Pronunciation Key  noun   [Semi-conductor Manufacturing] Aluminum Nitride, a compound of aluminum with nitrogen.
Ceramic substrate material used for heat dissipation.
A terms index



alumina — A ceramic used for insulators in electron tubes or substrates in thin film circuits. It can withstand continuously high temperatures and has a low dielectric loss over a wide frequency range.  Aluminum oxide (Al 2 O 3 )
A terms index



analog circuit — A circuit in which the output varies as a continuous function of the input, as contrasted with digital circuit.
A terms index



anode  — (AN-ohd) Pronunciation Key

  1. noun [Electronics] The positive element, such as the plate of a vacuum tube. The element to which the principal stream of electrons flows.
        
  2.  
  3. noun [Electronics] In a cathode-ray tube, the electrodes connected to a source of positive potential.
     These anodes are used to concentrate and accelerate the electron beam for focusing.   Graf_ Rudolf_F_MDE_Newnes_1999
A terms index



ANT — (ANT)  Pronunciation Key  noun  [Communications Technology] Adaptive Network Technology. A radio transceiver protocol, ANT is a proprietary wireless sensor network technology featuring a wireless communications protocol stack that enables semiconductor radios operating in the 2.4 GHz Industrial, Scientific and Medical allocation of the RF spectrum ("ISM band") to communicate by establishing standard rules for co-existence, data representation, signalling, authentication and error detection.
ANT is ported to a semiconductor transceiver from a specialist manufacturer (typically Nordic Semiconductor of Oslo, Norway) for practical implementations. ANT is characterized by a low computational overhead, and high efficiency that results in low power consumption by the radios supporting the protocol.
A terms index



antipad — (ANT-tee-pad)  Pronunciation Key  noun  [PCB Manufacturing] The diameter of the copper free area around a plated-through hole (PTH) in a power plane, which electrically isolates the PTH from the power plane.
In a negative image power plane, an antipad is created by placing a disc shaped object larger than the PTH and centered on it in the power plane artwork. Since this is a negative image, which means anything black on a transparent flim photoplot represents an absence of copper, the object forces a keepout of copper in the power plane as manufactured in the PCB. The drill dia + 0.020 in. (20 mils or 0.5 mm) is an acceptable ground rule for the antipad land size, although some board houses will require more than this. To specify the size of the antipad, the padstack can be edited for that hole, either in the footprint of the part in the PCB library or directly in the PCB file. In advanced PCB design packages such as Altium Designer, rather than edit the padstack, one creates a design rule that automatically creates the antipad. The easiest way to alter the size of an antipad is to edit the power plane clearance distance.

power plane clearance


Altium design rules - power plane clearance

A terms index



aperture  — (A-pə-chər) Pronunciation Key

  1. noun [Photoplotting] An indexed shape with a specified x and y dimension, or line-type with a specified width, used as a basic element or object by a photoplotter in plotting geometric patterns on film.
    The index of the aperture is its Position (a number used in an aperture list to identify an aperture) or D code     
  2.  
  3. noun [Photoplotting] A small, thin, trapezoidal piece of plastic used to limit and shape a light source for plotting light patterns on film, and mounted in a mechanical disk called an "aperture wheel," which in turn is mounted on the lamp head of a vector photoplotter. An aperture is mostly opaque, but with a transparent portion that controls the size and shape of the light pattern.
     A vector photoplotter plots images from a CAD file. It plots on photographic film in a darkroom. It plots lines by drawing each line with a continuous lamp shined through an annular-ring aperture. It creates shapes (or pads) by flashing the lamp through a specially sized and shaped aperture.   
  4.  
  5. noun [Photoplotting] A line of textual data in an aperture list describing the index names (D code and position), the shape, the usage(flash or draw) and the X and Y dimensions of an aperture.
     Some aperture lists leave out certain of those types of data. For example, laser photoplotters don't need to know whether an aperture is a flash or draw, so a modern-day aperture list might leave that datum out.   
A terms index

TOP


aperture list  — (A-pə-chər list) Pronunciation Key

  1. noun [Photoplotting] An ASCII text data file which describes the size and shape of the apertures used by a photoplotter for any one photoplot.
        
  2.  
  3. noun [Photoplotting] A print-out of this file.
        
  4.  
  5. noun [Photoplotting] A binary version of this file. [Also called "aperture table."]
        

A terms index



aperture table — See aperture list.
A terms index



aperture wheel — A component of a vector photoplotter , it is a metal disk having cut-outs with brackets and screw holes arranged near its rim for attaching apertures. Its center hole is attached to a motorized spindle on the lamp head of the photoplotter. When a D code denoting a particular position on the wheel is retreived from a Gerber file by the photoplotter, the wheel is caused to rotate so that the aperture in that position is placed between the lamp and the film.

In preparation for a photoplotting, the aperture wheel is set up by a technician who reads a printed aperture list , selects the correct aperture from a set of them stored in a box with compartments and, using a small screw driver, installs the aperture onto the position on the wheel which is called for on the list. This process is subject to human error and is one of the disadvantages of vector photoplotters as compared with laser photoplotters.

A terms index



ARM — (AHRM)  Pronunciation Key  noun  [Electronics] Advanced RISC Machine. RISC stands for Reduced Instruction Set Computing.
The ARM technology is licensed by ARM Holdings
A terms index



artwork — Artwork for printed circuit design is photoplotted film (or merely the Gerber files used to drive the photoplotter), NC Drill file and documentation which are all used by a board house to manufacture a bare printed circuit board. See also Valuable Final Artwork.
A terms index



ASCII — American Standard Code for Information Interchange.   A text and control-code character set used in computers.  Pronounced "ASS-key."  

(Note:  The following description is excerpted from "FOLDOC," Free Online Dictionary of Computing. The links in this definition point to FOLDOC and will take you off this site unless you right-click on the link and select "Open link in new tab" .)

ASCII is the basis of character sets used in almost all present-day computers. US-ASCII uses only the lower seven bit s (character points 0 to 127) to convey some control codes , space, numbers, most basic punctuation, and unaccented letters a-z and A-Z. More modern coded character sets (e.g., Latin-1 , Unicode ) define extensions to ASCII for values above 127 for conveying special Latin characters (like accented characters, or German ess-tsett), characters from non-Latin writing systems (e.g., Cyrillic, or Han characters ), and such characters as distinct open- and close-quotation marks (“ and ”), ¾ and ®.

The complete ASCII character set known as "Latin-1", an extension to 256 characters of the US-ASCII 128-character set, has been provided online by Paul Lutus at Arachnoid.com.
A terms index



ASCII text — A thoroughly unoffical subset of US-ASCII which contains the space character, numbers, most basic punctuation, and unaccented letters a-z and A-Z, but lacks the control codes.
A terms index



assembly

  1. The process of positioning and soldering components to a PCB.  
  2. Act or process of fitting together parts to make a whole.
A terms index



assembly drawing — A drawing depicting the locations of components, with their reference designators , on a printed circuit. Also called "component locator drawing."
A terms index



assembly house — A manufacturing facility for attaching and soldering components to a printed circuit. Aka assembler and also CM, for contract manufacturer.
A terms index



ASTM — American Society of Testing and Materials.   http://www.astm.org/index.shtml
A terms index



ATE — Automatic Test Equipment. (See also DUT.) .
A terms index



AWG — American Wire Gauge.  A PCB Designer needs to know diameters of wire gauges to properly size E-pads. The American Wire Gauge, formerly known as the Brown and Sharpe (B + S) Gauge, originated in the wire drawing industry.  The gauge is calculated so that the next largest diameter always has a cross-sectional area that is 26% greater.
A terms index



auto-router — automatic router, a computer program that routes a PC board design (or a silicon chip design) automatically.
A terms index



      

B

TOP



ball grid array (Abbrev. BGA).   A flip-chip type of package in which the internal die terminals form a grid-style array, and are in contact with solder balls ( solder bumps ), which carry the electrical connection to the outside of the package. The PCB footprint will have round landing pads to which the solder balls will be soldered when the package and PCB are heated in a reflow oven. Advantages of the ball grid array package are (1) that its size is compact and (2) its leads do not get damaged in handling (unlike the formed "gull-wing" leads of a QFP ' ) and thus has a long shelf life. Disadvantages of the BGA are 1) they, or their solder joints, are subject to stress-related failure. For example, the intense vibration of rocket-powered space vehicles can pop them right off the PCB, 2) they can not be hand-soldered (they require a reflow oven), making first-article prototypes a bit more expensive to stuff , 3) except for the outer rows, the solder joints can not be visually inspected and 4) they are difficult to rework.
B terms index



base — The electrode of a transistor which controls the movements of electrons or holes by means of an electric field on it. It is the element which corresponds to the control grid of an electron tube.
B terms index



beam lead A metal beam (flat metallic lead which extends from the edge of a chip much as wooden beams extend from a roof overhang) deposited directly onto the surface of the die as part of the wafer processing cycle in the fabrication of an integrated circuit. Upon separation of the individual die (normally by chemical etching instead of the conventional scribe-and-break technique), the cantilevered beam is left protruding from the edge of the chip and can be bonded directly to interconnecting pads on the circuit substrate without the need for individual wire interconnections. This method is an example of flip-chip bonding, contrasted with solder bump.   [Graf]
B terms index



BGA Ball Grid Array.



board — printed circuit board. Also, a CAD file which represents the layout of a printed circuit.
B terms index

``

board house — Board vendor. A manufacturer of printed circuit boards. Aka fabricator.
B terms index



body — The portion of an electronic component exclusive of its pins or leads.
B terms index




BOM — [pronounced "bomb"] Bill of Materials. A list of components to be included on an assembly such as a printed circuit board. For a PCB the BOM must include reference designators for the components used and descriptions which uniquely identify each component. A BOM is used for ordering parts and, along with an assembly drawing , directing which parts go where when the board is stuffed.
B terms index



      

C

TOP



C4 — Controlled Collapsed Chip Connect. A type of flip-chip technology which is used in Intel's Pentium III™ and in Motorola's PowerPC 603™ and PowerPC 604™ RISC Microprocessors. Here is an Friday, February 07, 2003 introduction to the C4/CBGA interconnect technology by Kromann, Gerke and Huang of Motorola's Advanced Packaging Technology Division. <
C terms index/p>

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 electronics, the result would be a printed circuit layout.
C terms index



CADCAM — Simply a concatenation of the two terms CAD and CAM.
C terms index



CAE — Computer Assisted Engineering. In electronics work, CAE refers to schematic software packages.
C terms index



CAF — Conductive Anodic Filamentation (or Conductive Anodic Filament growth) - An electrical short which occurs in PCBs when a conductive filament forms in the laminate dielectric material between two adjacent conductors under an electrical bias. CAF is a potentially dangerous source of electrical failure in the PCB.  As PCB designs have increased in density, with hole-to-hole spacings reduced to 25 mils or less, CAF has become an everyday concern. [adapted from Erik J. Bergum, "CAF Resistance of NON-DICY FR-4," PC FAB , 9/2002]
C terms index



CAM — Computer Aided Manufacturing.  (See CAM files )
C terms index



CAM files — CAM means Computer Aided Manufacturing. These are the data files used directly in the manufacture of printed wiring. . The types of CAM files are 1) Gerber file, which controls a photoplotter, 2) NC Drill file, which controls an NC Drill machine and 3) fab and assembly drawings in soft form (pen-plotter files). CAM files represent the valuable final product of PCB design. They are handed off to the board house which further refines and manipulates CAM data in their processes, for example in step- and-repeat panelization. Some PCB design software companies refer to all plotter or printer files as CAM files , although some of the plots may be check plots which are not used in manufacture.
C terms index



capture v. 1.   To draw (schematics) with CAE software in such a way that data, especially connectivity, can be extracted electronically. The extracted data would minimally be a netlist and preferably also a BOM. The more useful the data that is included in the schematic, the more useful will be the BOM and netlist extracted from it will be.
2.   Extract data from a CAE schematic. E.g. " Capture a netlist."
n. The process of creating a CAE drawing containing intelligent data. E.G. "Schematic capture."
C terms index



card — another name for a printed circuit board.
C terms index



card-edge connector — A connector which is fabricated as an integral portion of a printed circuit board along part of its edge. Often employed to enable a daughter or add-on card to be plugged directly into another much larger printed board, the motherboard or backplane. See finger .
C terms index



capture — Extract information automatically through the use of software, as opposed to hand-entering of data into a computer file.
C terms index



cathode — 1.  In an electron tube the electrode through which a primary source of electrons enters the interelectrode space. 2.  General name for any negative electrode.   3.  When a semiconductor diode is biased in the forward direction, that terminal of the diode which is negative with respect to the other terminal.  4.  In electrolytic plating, the workpiece being plated.   [Graf]
C terms index



CBGA — Ceramic Ball Grid Array.
C terms index



CEM-1 — A NEMA grade of industrial laminate having a substrate of woven glass surfaces over a cellulose paper core and a resin binder of epoxy. It has good electrical and mechanical properties, somewhat surpassed by those of FR-4.
C terms index



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



chip — 1. An integrated circuit manufactured on a semiconductor substrate and then cut or etched away from the silicon wafer.  (Also called a die.) A chip is not ready for use until packaged and provided with external connections.  2.   Commonly used to mean a packaged semiconductor device.
C terms index



chip on board — Abbreviated COB.  In this technology integrated circuits , small portions of silicon wafers, are glued and wire-bonded directly to printed circuit boards instead of first being packaged. The electronics for many mass-produced toys are embedded by this system, which can be identified by the black glob of plastic sitting on the board. Underneath that glob (technical term: glob top ), is a chip with fine wires bonded to both it and the landing pads on the board.



chip scale package a> — A chip package in which the total package size is no more than 20% greater than the size of the die within. Eg: Micro-BGA.



circuit design —The creation of the functional description and diagram (the schematic) of an electronic circuit. Done by an electrical engineer, this is NOT the same thing as "printed circuit design."
C terms index



CIM — Computer Integrated Manufacturing. Used by an assembly house, this software inputs assembly data from a PCB CAM/CAD package, such as Gerber and BOM , as input and, using a pre-defined factory modeling system, outputs routing of components to machine programming points and assembly and inspection documentation.  In higher end systems, CIM can integrate multiple factories with customers and suppliers.



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.
C terms index



collector — 1. An electrode in a transistor that collects electrons or holes. 2. In certain electron tubes, an electrode to which electrons or ions flow after they have completed their function.
C terms index



component — Any of the basic parts used in building electronic equipment, such as a resistor, capacitor, DIP or connector, etc.
C terms index



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



connection — One leg of a net. Also called a "pin pair" (PADS) and "from-to" (Protel).
C terms index



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



connector — 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.
C terms index



control code — A non-printing character which is input or output to cause some special action rather than to appear as part of the data. Control codes are generated by holding down the <Ctrl> key on your computer keyboard while pressing one of the letter keys (e.g. < CTRL-G>. Sometimes called "control characters."
C terms index



copper — A red-orange metallic element ideally suited for the wires used in construction of telephone and power lines, due to its strength and ductility and its pronounced ability to conduct electricity. It is also the most common conductor used as printed wires on or in printed circuit boards. Copper for construction of PCBs is provided in sheets called "foil."
C terms index


copper foil
— A sheet of copper of various thicknesses used for a conductive layer in the construction of a PCB stack-up (q.v.).
C terms index



core — A material used in printed circuit manufacturing. It is composed of fiberglass cloth impregnated with resin and cured (by baking in an oven) and it has a sheet of copper on one or both sides. The particular type of resin is usually either epoxy or polyurethane. The fiberglass cloth with cured resin is called "dielectric." The printed circuit manufacturer, or "board house," receives the core in its already-cured state in various thicknesses. The board house uses it along with other materials (foil and prepreg) to make a layer stack-up for a PCB.
C terms index



coupon — See test coupon.
C terms index



CSP Chip Scale Package or Chip Scale Packaging.
C terms index



      

D

TOP



D code — Draft code.  1.  A datum in a Gerber file which acts as a command to a photoplotter. A D code in a Gerber file takes the form of a number prefixed by the letter D, e.g. "D20". However, in some aperture lists the D is dropped. In aperture lists of Cadstar, the column heading "Position" actually refers to D code, and the D prefix is dropped. 2.  D codes have multiple purposes. The first is to control the state of the light being on or off. Valid codes for light state are D01, D02, and D03.

  1. D01 - Light on for next move.
  2. D02 - Light off for next move.
  3. D03 - Flash (Light On, Light Off) after move (effect is limited to block in which appears, i.e. non-modal). You can also think of a D03 as D02, D01, D02 series of commands linked together.

D codes with values of 10 or greater represent the aperture's position on the list or wheel. It is very important to understand that there is no universal "D10" or "D30". Unlike the D01 , D02, and D03 counterparts which have a fixed meaning ( draw , move, flash), D10 and higher values have aperture shapes and dimensions assigned to them by each individual user. Hence, one job's D10 could be a 10 mil Round, when another job's D10 could be a 45 mil Square.

There are two distinct ways to number an aperture list. The traditional 24 aperture system started with D10 - D19, jumping suddenly to D70 - D71, then back to D20 - D29, ending with D72 -D73. This is still a common format for output for CAD packages, and is still mandatory for old 24 aperture Gerber vector Photoplotters.

It is now common to start with D10, then increase numerically in steps of 1 (D10, D11, etc.) continuing up to D70 and beyond, rarely beyond 1000 individual apertures.
D terms index



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



Dcode D code.
D terms index



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.
D terms index



destructive testing — Sectioning a portion of printed circuit panel and examining the sections with a microscope. This is performed on coupons , not the funtional part of the PCB.
D terms index



device — Any type of electrical component on a PC board. It will have functions and properties unique to its type. In a schematic (and the extracted BOM ) , it will be labeled with a value or device number. There are two main classes of devices, passive and active.

D terms index



DICY — Dicyandiamide, the most common cross-linking agent used in FR-4. [Erik J. Bergum, "CAF Resistance of NON- DICY FR-4," PC FAB , 9/2002]
D terms index



die — 1.  A chip. (Plural: dice)
D terms index



dielectric constant — The ratio of the capacitance of a capacitor with the given dielectric to the capacitance of a capacitor having air for its dielectric but otherwise identical.   [Graf]

D terms index


 

 


differential signaling
— A method of signal transmission through two wires which always have opposite states. The signal data is the polarity difference between the wires:   Whenever either is high, the other is low. Neither wire is grounded.   [Graf]

For more information see the articles on this page:  
Douglas Brooks Articles on Differential Traces

Or see an alternative viewpoint: Differential Signaling Doesn't Require Differential Impedance Or, How to Design a Differential Signaling Circuit, by Lee W. Ritchey

Regarding this alternative view: At Golden Gate Graphics we follow the advice of Douglas Brooks, not Lee W. Richey. Does that mean Ritchey is wrong? No. We adopt this policy of applying differential impedance design rules to our PCB layouts which have differential signaling, because it is the more conservative approach and is more likely to please our customers. It might also mean the boards manufactured to employ differential impedance control with testing via coupons and TDR will be more expensive. If the customer does not want this expense, that is their choice. If our layouts have incorporated differential impedance design rules, they will still work as well as a layout done without that control.
D terms index



digital circuit — A circuit which operates like a switch (it is either "on" or "off"), and can make logical decisions. It is used in computers or similar decision making equipment.
D terms index



diode — 1.  A device, as a two-element electron tube or a semiconductor, through which current can pass freely in only one direction.  [Random House]   2.  A semiconductor device with two terminals and a single junction, exhibiting varying conduction properties depending on the polarity of the applied voltage. [Graf]

D terms index



DIP — Abbreviation for Dual In-line Package. A type of housing for integrated circuits. The standard form is a molded plastic container of varying lengths and 0.3 inch wide (although there are other standard widths), with two rows of through-hole pins spaced 0.1 inch between centers of adjacent pins.
D terms index



DNI — Do Not Install. Same use as DNP, which means "Do Not Populate "

D terms index



DNP — Do Not Populate. This acronym is often used on schematics to show that a component shown in the cirucit diagram is not actually placed and soldered on the finished printed circuit board during initial assembly. The footprint will be on the board, but no component will be there. This can allow an option for adding a componet of that size and shape later for experimentation and debuggin.
D terms index



DOS — Disk Operating System. A program that controls the computer's transfer of data to and from a hard or floppy disk. Personal computers that are IBM-compatible run DOS rather than other early varieties of operating systems.
D terms index



DOS-formatted — (Of magnetic data storage media, such as floppy disks.) Prepared for storage of data in such a way that DOS transfer can occur.



double-track — Slang for fine line design with two traces between DIP pins.
D terms index



draw — 1. v. To plot a line on film by moving the film while shining a light through an aperture.  2. n. A line plotted thus.
D terms index



dry film solder mask — 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.
D terms index



DUT — Device Under Test. A DUT board (probe card) is used in automated testing of integrated circuits. It is part of the interface between the chip and a test head, which in turn attaches to computerized test equipment. The specific test equipment used will determine the value of the controlled impedance required for the chip tester boards. For more on DUT boards, click here. Depending on which system it is designed for, one type of DUT board is used in testing individual integrated circuits in a silicon wafer before they are cut free and packaged, and another type is used for testing packaged IC 's.
D terms index



      

E

TOP



E-pad — "Engineering-pad." A plated-through hole or surface mount pad on a PCB placed on the board for the purpose of attaching a wire by soldering. These are usually labeled with silkscreen. E-pads are used to facilitate proto-typing, or simply because wires are used for interconnections instead of headers or terminal blocks.

E terms index



ECL — Emitter Coupled Logic.  A type of unsaturated logic performed by emitter-coupled transistors.  Higher speeds may be achieved with ECL than are obtainable with standard logic circuits. ECL is costly, power hungry, and difficult to use, but it is four times faster than TTL.   [Graf]

E terms index



electrical object [Protel] A graphical object (in a PCB or schematic file) to which an electrical connection can be made, such as a component pin or a wire.
E terms index



embedded — (Of a micro-processor(s), or system controlled by such) Dedicated to doing one job or supporting one device and built into the product.
E terms index



EMC — electromagnetic compatibility.  (1) The ability of electronic equipment to operate without degradation in an intended electromagnetic environment (2) The ability of equipment to operate in its electromagnetic environment without creating interference with other devices. [From the National Instruments, Developer Zone, Measurement Encyclopedia , which unfortunately has gone off-line as of 2017]  At circuit board level, one could substitue the term circuit for equipment in the above definitions.  Eg.   "If the ground returns are common, they can be connected at a single point near the external ground connection, which is good EMC practice." -- Jon Berrie, Technical Marketing Specialist Hot-Stage, Zuken.

E terms index



emitter — An electrode on a transistor from which a flow of electrons or holes enters the region between the electrodes. [Random House]

E terms index



EMP — Electromagnetic pulse. A reaction of large magnitude resulting from the detonation of nuclear weapons. [Graf]

E terms index



ENIG — Electroless Nickel Immersion Gold. A printed circuit finish composed of a 3-5 micro-inches [0.08-0.13 microns] of gold plated electrolessly over 100-150 micro-inches [2.54-3.81 microns] of nickel, which has been plated electrolessly over the copper. The gold prevents the nickel from tarnishing.

ENIG is preferred over HASL (Hot Air Solder Level) for fine pitch SMT, because HASL leaves solder bumps. ENIG is also a great finish for lead-free solder assembly. In many board houses, this finish is actually cheaper than lead-free HASL. foil— A sheet of copper of various thicknesses used as an electrical layer in the construction of a PCB stack-up.
E terms index



end-to-end design — a version of CADCAM CAE in which the software packages used and their inputs and outputs are integrated with each other and allow design to flow smoothly with no manual intervention necessary (other than a few keystrokes or menu selections) to get from one step to the other. Flow can occur in both directions. In the field of PCB design, end-to-end design sometimes refers to only the electronic schematic/pcb layout interface, but this is a narrow view of the potentialities of the concept. For example, end-to-end systems can also implement electronic circuit simulation, parts procurement and beyond. For an introduction to the overall design flow of an electronics project, see the PCB designer definition and follow the link to the plain English description for a printed circuit board designer
E terms index



Excellon — NC Drill file format. An ASCII format used in a file which drives an NC Drill machine. The earliest NC Drill machines were made by Excellon Automation Company. The format is in broad use, although the company has been sold.
E terms index



      

F

TOP



fab — Short for fabrication.
F terms index



fabrication drawing — A drawing used to aid the construction of a printed board. It shows all of the locations of the holes to be drilled, their sizes and tolerances, dimensions of the board edges, and notes on the materials and methods to be used. Called "fab drawing" for short. It relates the board edge to at least on hole location as a reference point so that the NC Drill file can be properly lined up.
F terms index



FC — Flexible Circuit, flexible circuitry, flexcircuit or flex circuit.

F terms index


fine line design — Printed circuit design permitting two (rarely three) traces between adjacent DIP pins. It entails the use of a either dry film solder mask or liquid photoimageable solder mask (LPI), both of which are more accurate than wet solder mask.
F terms index



fine pitch — Refers to chip packages with lead pitches below 0.050". The largest pitch in this class of parts is 0.8mm, or about 0.031". Lead pitches as small as 0.5mm (0.020") are used.
F terms index



finger — A gold-plated terminal of a card-edge connector. [Derived from its shape.]
F terms index



flash — 1. v. To turn a vector photoplotter lamp on for a brief but precise duration and then off, during which time the relative positions of the lamp and film remain fixed. This exposes the film with the image of a small object (the size and shape of which is controlled by the transparent portion of an aperture ).  2. n. A small image on film created in such wise or as directed by a command in a Gerber file.) The maximum size (x or y dimension)for a flash varies from one photoplotting shop to another, but is commonly ½ inch.
F terms index



flex circuit — Flexible circuit, or flexcircuit; a printed circuit made of thin, flexible material. For more information, see flexible circuitry.
F terms index



flexcircuit — See flex circuit.
F terms index



flexible circuitry — An array of conductors bonded to a thin, flexible dielectric. It has the unique property of being a three-dimensional circuit that can be shaped in multiplanar configurations, rigidized in specific areas, and molded to backer boards for specific applications. As an interconnect, the main advantages of flex over traditional cabling are greater reliability, size and weight reduction, elimination of mechanical connectors, elimination of wiring errors, increased impedance control and signal quality, circuit simplification, greater operating temperature range, and higher circuit density.



flexible printed circuit Flex circuit. Abbreviated FPC or FC.
F terms index



flip-chip — A mounting approach in which the chip ( die ) is inverted and connected directly to the substrate rather than using the more common wire bonding technique. Examples of this kind of flip-chip mounting are beam lead and solder bump.

F terms index



first article — A sample part or assembly manufactured prior to the start of production for the purpose of ensuring that the manufacturer is capable of manufacturing a product which will meet the requirements.   [Graf]

F terms index



foil — A sheet of copper of various thicknesses used most commonly as an outer layer in the construction of a PCB stack-up (q.v.).
F terms index



footprint Click here for an action definition of footprint. 1. The pattern and space on a board taken up by a component. 2. Decal.

F terms index



FPC — Flexible Printed Circuit, or flex circuit.

F terms index



FR-1 — A low-grade version of FR-2.
F terms index



FR-2 — A NEMA grade of Flame-Retardant industrial laminate having a substrate of paper and a resin binder of phenolic. It is suitable for printed circuit board laminate and cheaper than the woven glass fabrics such as FR-4.
F terms index



FR-4 — A NEMA grade of Flame-Retardent industrial laminate having a substrate of woven-glass fabric and resin binder of epoxy. FR-4 is the most common dielectric material used in the construction of PCBs in the USA.  Its dielectric constant is from 4.4 to 5.2 at below-microwave frequencies. As frequency climbs over 1 GHz, the dielectric constant of FR-4 gradually drops.
F terms index



FR-6 — Fire-Retardant glass-and-polyester substrate material for electronic circuits. Inexpensive; popular for automobile electronics. [Stammtisch Beau Fleuve Acronyms http://www.plexoft.com/SBF/F05.html#FR-4]

An article written in 2015 by Atar Mittal is worth study if you need to choose PCB materials for your electronics project. It includes a "Laminate Selector Chart" entitled "PCB Material Properties and Recommended Application Areas" HDI PCBs: Choosing The Right Material

A comparison of many brands of PCB laminates can be found at the Standard Printed Circuits "Microwave Laminates Comparison Chart".



      

G

TOP


GC-Prevue — A CAM file viewer and printer made by Graphicode. Their low cost version can store Gerber and NC Drill files within a file (.GWK extension), which makes it extremely useful for sharing electronic data:   It can be used for importing Gerber files in a logical sequence, displaying them in perfect register , annotating (adding labels to the filenames to describe their use and position in the stackup) and viewing them, saving all that and then passing the resulting .GWK file on to another for examination. Besides merely looking at the files or printing them, GC-Prevue has features for measuring objects' size and relative distance from each other. GC-Prevue sets-up and saves Gerber data in a single file. Free Gerber viewers require one to set up the Gerber files each time and won't allow saving the set-ups unless one buys an upgrade. (From the viewpoint of a printed circuit designer serving engineers or customers, this inability to save set-ups makes the free Gerber viewers completely useless for sharing Gerber data.)
G terms index




gerber or

Gerber
— see Gerber file.

G terms index



Gerber file — ASCII data file used to control a photoplotter. Named after H. Joseph Gerber, founder of Gerber Scientific Co., who invented the original vector photoplotter.

G terms index



glob top — A blob of non-conductive plastic, often black in color, which protects the chip and wire bonds on a packaged IC and also on a chip on board. This specialized plastic has a low coefficient of thermal expansion so that ambient temperature changes will not rip loose the wire bonds it is designed to protect. In high-volume chip on board production, these are deposited by automated machinery and are round. In prototype work, they are deposited by hand and can be custom-shaped; however, in designing for manufacturability, one assumes a prototype product will "take- off" and ultimately have high market demand, and so lays out chip on board to accommodate a round glob top with adequate tolerance for machine-driven "slop-over".
G terms index



      

H

TOP



hard copy — A printed or plotted form of an electronic document (computer data file).
H terms index



header — The portion of a connector assembly which is mounted on a printed circuit.
H terms index



hole — In a semiconductor, the term used to describe the absence of an electron; has the same electrical properties as an electron except that it carries a positive charge.   [Graf]

H terms index



HPGL — Hewlett-Packard Graphics Language, a text-based data structure of pen-plot files which are used to drive Hewlett-Packard pen plotters. Although Hewlett-Packard no longer makes pen plotters, the large-format dot matrix printers which replaced them can also be driven by HPGL.
H terms index



hybrid — Hybrid circuit. Any circuit made by using a combination of the following component manufacturing technologies: monolithic IC , thin film , thick film and discrete component.



      

I

TOP



IC Integrated Circuit.

I terms index



integrated circuit — 1)miniaturized electronic circuit that has been manufactured as a chip ( die ). 2)A packaged chip.
I terms index



IPC — The Institute for Interconnecting and Packaging Electronic Circuits, the final American authority on how to design and manufacture printed wiring.   In 1999, IPC changed its name from Institute of Interconnecting and Packaging Electronic Circuits to IPC. The new name is accompanied with an identity statement, Association Connecting Electronics Industries.
(IPC Home Page) >

I terms index



      

J

TOP
J terms index


      

K

TOP


K terms index.


      

L

TOP



laser photoplotter — (also "laser plotter") A photoplotter which simulates a vector photoplotter by using software to create a raster image of the individual objects in a CAD file, then plotting the image as a series of lines of dots at very fine resolution. A laser photoplotter is capable of more accurate and consistent plots than a vector photoplotter.
L terms index.



lead (pronounced "leed") A terminal on a component.
L terms index



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. It is often preferred for dense SMT.
L terms index



LPI — stands for Liquid PhotoImageable. Refers to liquid photoimageable solder mask.
L terms index



      

M

TOP



Manhattan algorithm — An algorithm to determine a cross street for an avenue address in Midtown Manhattan New York City, or for the length of a trip from one address in Manhattan to another. If you know the building addresses for where you are and where you want to go in Manhattan, you can call a cab company and find out what it will cost you. An algorithm is used to get the answer, because in Manhattan the street and avenue numbers do not necessarily correspond intuitively to the building numbers. To see an example of the Manhattan algorithm as an intersection locator, go to http://www.ny.com/locator/. What does this have to do with PCB design? The Manhattan algorithm has many variations and uses in various branches of mathematics, including the mathematics of auto-routers.  See also Manhattan length.

M terms index



Manhattan length — The length of the two sides of a right triangle as a distance between two points, as opposed to the hypotenuse.. (Derived from the Manhattan algorithm for determining the length of a taxicab trip following streets and avenues on the island of Manhattan, NY.)  Routing of traces in orthagonal patterns in a PCB design, or in a semiconductor chip, follows the same pattern as streets and avenues in a city.  The minimum distance between two component leads, or two nodes on a chip, when routing on 90 degrees is the Manhattan length .

 Advanced PCB auto-routers permit specification of maximum length of classes of nets as a percentage of Manhattan length . For example, one could specify clocks as 120% and random nets as 160% of Manhattan length . (This percentage, expressed as a ratio, becomes the "Manhattan coefficient", ie. a Manhattan coefficient of 1.2 means the routed length is 120% of the Manhatten length .) Specifying such limits on the auto-router prevents long and circuitous routes.
M terms index



master aperture list — 1. An aperture list which is used for every PCB designed by a PCB design service bureau or department.  If a new design requires one or more new apertures, they are added to the list, either at the end or in some previously unused positions set aside for that purpose. The previously used aperture positions are never edited to change their parameters. Thus the updated list can still be used as a master for any previous PCB's designed. This type of master aperture list became possible only with the advent of laser photoplotters , which can have upwards of 1000 positions if need be.  2. Any aperture list which is used with two or more PCB's would be called the master aperture list for that set of PCB's.
M terms index



MCR — Molded Carrier Ring. A type of fine-pitch chip package named for the method of supporting and protecting the leads. The leads are left straight; the ends of the leads are embedded in a strip of plastic, which is the Molded Carrier Ring. Just before assembly (placing on a PCB for soldering), the MCR is cut off and the leads are formed. In this way, the delicate leads are protected against damage in handling until just before assembly.
M terms index



MELF — Metal ELectrical Face - A surface mount discrete part, usually a diode, that is barrel shaped, or cylindrical. The ends of the "barrel" are capped with metal, the "metal electrical face." The "barrel" is laid on its side, the metal ends upon landing pads, and the part is soldered that way. The two most common sizes are MLL34 and MLL41, which are roughly MELF versions of a DO-35 and DO-41 respectively.
M terms index



MIC Monolithic Integrated Circuit.

M terms index



micro ball grid array — A fine pitch ball grid array. Fine pitch for BGAs is anything equal to or less than 0.5 mm [19.7 mil ]. In practice, a micro-BGA is one that is so dense, it requires controlled-depth laser-drilled blind microvia-in-pad technology.
M terms index



micro-BGA micro Ball Grid Array.



mil — One thousandth of an inch (0.0254 mm). [From abbreviation of mil li-inch, which means one-thousandth of an inch.]
M terms index



MLC — Multi-Layer Ceramic
M terms index



monolithic — 1.  Existing as one large, undifferentiated whole.  2.  (of an integrated circuit or its elements) built upon or formed within a single slice of silicon substrate.
M terms index



monolithic integrated circuit — 1.  Abbreviated MIC. An integrated circuit formed upon or within a semiconductor substrate with at least one of the circuit elements formed within the substrate.    2.  A complete electronic circuit fabricated as an inseparable assembly of circuit elements in a single small structure. It cannot be divided without permanently destroying its intended electronic function.   [Graf]

M terms index



MTF — Multi-layer Thin Film.

M terms index



mullite — A substrate compound of alumina and silica (3Al 2 O 3 •2SiO 2 ).

M terms index



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



      

N

TOP



NC drill — Numeric Controlled (computer controlled) drill machine. A machine used to drill the holes in a printed board at exact locations, which are specified in a data file. Also known as CNC (Computerized Numeric Controlled) drill machine.
N terms index


NC drill file — A text file which tells an NC drill where to drill its holes.
N terms index



negative

  1. noun . A reverse-image contact copy of a positive, useful for checking revisions of a PCB. If the negative of the current version is superimposed over a positive of an earlier version, all areas will be solid black except where changes have been made.
  2. modifier . (Of a PCB image) Representing copper (or other material) as clear areas and absence of material as black areas. Typical of power and ground planes and solder mask.


N terms index



NEMA National Electrical Manufacturers Association

N terms index



net — A collection of terminals all of which are, or must be, connected to each other electrically. Also known as a signal.
N terms index



netlist — List of names of symbols or parts and their connection points which are logically connected in each net of a circuit. A netlist can be "captured" (extracted electronically on a computer) from a properly prepared CAE schematic. .

N terms index



node — A pin or lead which will have at least one wire connected to it. In a netlist, a node is described by a component reference desginator together with a pin number.
N terms index



      

O

TOP



open — Open circuit. An unwanted break in the continuity of an electrical circuit which prevents current from flowing.
O terms index



      

P

TOP



package — 1) Decal or printed wiring board component.  2) A type of PCB component which contains a chip and acts to make a convenient mechanism for protecting the chip while on the shelf and after attachment to a PCB. With its leads soldered to a printed circuit board, a package serves as the electrical conduction interface between the chip and the board. An example is a DIP.



panel — material (most commonly an glass/epoxy-copper laminate known as core) sized for fabrication of printed circuit boards. Panels come in many, many sizes, the most common being 12" by 18" and 18" by 24". Subtract 1/2" to 1" margins (check with your board house) from the panel size to arrive at the space available for printed circuitry.
P terms index



panelize — 1. To lay up more than one (usually identical)printed circuits on a pans. Individual printed circuits on a panel need a margin between them of 0.3". Some board houses permit less separation. 2. Lay up multiple printed circuits (called modules) into a sub-panel so that the sub-panel can be assembled as a unit. The modules can then be separated after assembly into discrete printed circuits.
P terms index



part — 1. Component. 2. A decal in a PWB file or drawing. 3. A symbol in a schematic.
P terms index



passive component — A device which does not add energy to the signal it passes. Examples: resistor, capacitor, inductor. (Contrast with active component.

P terms index



PC board Printed Circuit board.

P terms index



PCB Printed Circuit Board.

P terms index



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



PCB design — 1. The creation of artwork for the manufacture of bare PCBs. 2. The artwork so created. 3. A computer file (for example, an Altium Designer file with the extension .PcbDoc) from which artwork can be generated as data files ( CAM files ). Also called PCB layout.
P terms index


 

 

 

 


PCB designer — One who creates the artwork for printed circuit boards.   For you recruiters out there who are asked to find one, and for anyone else interested, here is a plain English description for a Printed Circuit Board Designer. Hint: It is not the same as an electrical engineer.
P terms index


 

 

 


PCB design service bureau
— A business engaged in PCB design as a service for others, especially electrical engineers. The word bureau is French for desk, or office, and this service is indeed performed from an office while sitting at a desk. Also called PCB design shop.
P terms index



PCB layout PCB design.

P terms index



PCMCIA — An acronym which means: "People Can't Memorize Computer Industry Acronyms." Wait a minute. That's WRONG! Click here to find out its true meaning: Personal Computer Memory Card International Association

P terms index



photoplotter — Device used to generate artwork photographically by plotting objects (as opposed to copying an entire image at once as with a camera) onto film for use in manufacturing printed wiring.
P terms index



pin — 1.  A terminal on a through-hole component. [Derived from its physical shape on through-hole components, which predated SMT.] Also called lead. 2. In the term "pin count," pin refers to a terminal on any component, whether through-hole or SMT.
P terms index



pin-out — Pin-number assignment, the relation between the logical inputs and outputs of an electronic device and their physical counterparts in the PCB package. pin-outs will involve pin numbers as a link between schematic and PCB design (both being computer generated files). In more complicated packages, they may also involve pin names. Even for devices with only two pins and no polarity, such as resistors, the netlist 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. (The visibility in the schematic of the pin numbers can be turned on or off at will, but the significance of the pin number assignment is still there in the schematic and subsequently, through the netlist extracted from it, the PCB database.) For CAD CAE electronics to work at all, the pin-outs for the PCB database must agree with the schematic.
P terms index



PI — Polyimide. (Also Pi)
P terms index



plasma — A highly-ionized gas containing an approximately equal number of positive ions and negative electrons. Thus, as a whole it is electrically neutral, though conductive and affected by magnetic fields.
P terms index



plated-through hole — A hole in a PWB 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.  In PCB vernacular and documentation, the spelling of the word through is sometimes shortened to thru.
P terms index


Plastic Leaded Chip Carrier — An SMT chip package that is rectangular or square- shaped with leads on all four sides. The leads are spaced at 0.050 inches, so this package is not considered fine-pitch.
P terms index



populate — Install (place, attach and solder) components onto (a printed wiring board ). (Slang) Also known as " stuff." This can refer to a single component, as in the acronym used in schematics "DNP", which means "Do Not Populate".
P terms index



Pos — An abbreviation for Position used by GC-Prevue.
P terms index



position — A type of index for an aperture in an aperture list which is a number from 1 to the number of apertures in the aperture list. Position 1 is linked to D code D10, 2 is D11 and so on. Positions appear only in aperture lists, and never in a Gerber file.  Cadstar aperture lists use the column heading Position to mean D code.  Abbreviated "Pos" in GC-Prevue.
P terms index



positive noun A developed image of photoplotted film, where the areas selectively exposed by the photo plotter appear black, and unexposed areas are clear. Board houses work from positives, and a photo plotter produces positives, thus one set of positives is all the film that is needed to produce a printed wiring board. modifier (of a printed wiring image) Representing copper as black areas and absence of copper as clear areas. Typical of images of routed layers of a PWB.
P terms index



PQFP — Plastic Quad Flat Pack. See QFP.

P terms index



prepreg — Fiberglass cloth pre-impregnated with uncured resin. The particular type of resin is usually either epoxy or polyurethane. Prepreg is dialectric only, so use of it requires an accompanying layer of copper foil.Printed board layer stackups of 4 or more layers typically employ prepreg along with core and copper foil (q.v.).
P terms index



primitive — (Found in CAD software programs and documentation)   1.  Some CAD software documentation (especially Altium Designer) extends this term to mean any object in a CAD database--graphics, text or otherwise; so this could be a group of graphic objects if manipulated as a unit, eg. a PCB decal.   It may also mean an indivisible graphic object, i.e. a graphical object which may have component parts, but which can not have those parts separated out as individual entities. It can also refere to a parameter or text string. Examples of this in PCB CAD: wire segment, route, pad or padstack, text string. 2. Any geometric shape such as a circle, polygon or square.   3. A function, operator, or type which is built into a programming language (or operating system), either for speed of execution or because it would be impossible to write it in the language. Primitives typically include the arithmetic and logical operations (plus, minus, and, or, etc.) and are implemented by a small number of machine language instructions. [ FOLDOC - Free Online Dictionary of Computing , © 1993-2002 Denis Howe, editor, used with permission.]



printed circuit board

  1. A flat plate or base of insulating material containing a pattern of conducting material and components placed and soldered to it. It is an electrical circuit. It is a " printed wiring board " (PWB) that has been " stuffed."
  2. 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. But there are many other kinds of materials used in more exotic technologies.
  3. Single-sided boards, the most common style in mass-produced consumer electronic products, 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.
  4. A PCB without the components, a "bare board" or a printed wiring board.


P terms index



probe card DUT board.
P terms index



PWA — Printed Wiring Assembly; same as PCB. A PWA is a bare board ( PWB ) that has been populated.

P terms index



PWB — 1. Printed Board. According to IPC, PWB is an older term that they prefer no longer be used. 2. Some electrical engineers use PWB to distinguish from PCB . PWB stands for Printed Wiring Board; a "bare board"; an unstuffed PCB. It is flat plate or base of insulating material containing a pattern of conducting material. It is not an electrical circuit until components are placed and soldered to it.

The acronynm PWB , followed by a part number, can be included in clad , sometimes in both clad and silkscreen , on a PWB
P terms index



      

Q

TOP



QFP — Quad Flat Pack, a fine-pitch SMT package that is rectangular or square with gull-wing shaped leads on all four sides. The lead pitch of a QFP is typically either 0.8mm or 0.65mm, although there are variations on this theme with smaller lead pitches: TQFP also 0.8mm; PQFP tooled at either 0.65mm (0.026") or 0.025" and SQFP at 0.5mm (0.020"). Any of these packages can have a wide variety of lead counts from 44 leads on up to 240 or more. Although these terms are descriptive, there are no industry- wide standards for sizes. Any printed circuit designer will need a spec sheet for the particular manufacturer's part, as a brief descrition like "PQFP-160" is inadequate to define the mechanical size and lead pitch of the part.
Q terms index



      

R

TOP



ratsnest — A bunch of straight lines (unrouted connections) between pins which represents graphically the connectivity of a PCB CAD database. [Derived from the pattern of the lines: as they crisscross the board, the lines form a seemingly haphazard and confusing mess similar to a rat 's nest.)
R terms index



reference designator — (abbrv. "ref des") The name of a component on a printed circuit by convention beginning with one or two letters followed by a numeric value. The letter designates the class of component; eg. "Q" is commonly used as a prefix for transistors. Reference designators appear as usually white or yellow epoxy ink (the "silkscreen") on a circuit board. They are placed close to their respective components but not underneath them, so that they are visible on the assembled board. By contrast, on an assembly drawing a reference designator is often placed within the boundaries of a footprint --a very useful technique for eliminating ambiguity on a crowded board where reference designators in the silkscreeen may be near more than one component.
R terms index



register — In printed board manufacture, many terms are borrowed from the subject of printing.   Register has the following specialized printing definition from Macmillan Dictionary for Students :

(noun) proper alignment of various plates, stones, or screens to assure clear and accurate reproduction, as of color.   Examples: in register, off register.

In printed circuit design, the designer gets his photoplot files in register before he views them with his Gerber file viewer.  The board manufacturer produces film from the Gerber files and uses them in register with respect to the panels of material from which he will build the boards.  He is going to want the pads on both sides and on internal layers to be in register before he drills holes in the panel.

[ Usage note: The term registration is often used in the printed circuit industry for this sense of the noun register . Register , already being a noun, doesn't need the suffix -tion added to it to make it a noun. You wouldn't say, "Count the money in the cash registration."  This misuse of registration has become so common that it has entered the literature of PCB design and manufacturing.  How illiterate we must sound to professional printers when we say "registration" when we mean "register!" ]
R terms index



registration — See register.
R terms index



RF — Radio Frequency.
R terms index



rise time — the time required for an output voltage of a digital circuit to change from low voltage level (0) to high voltage leve (1), after the change has started. (For more defintions of the term, see Modern Dictionary of Electronics , by Rudolf F. Graf.)
   Very short rise times, not high clock speeds, are the primary cause of cross-talk in PCBs. Rise times are charactericstic of the technology being used in a circuit. Gallium Arsenide components can have rise times around 100-picoseconds (millionths of millionths of seconds), 30 to 50 times faster than some CMOS components.
   A warning for PCB designers. In today's monolithic IC's, rise times have generally shortened to much less than they typically were before 1990. Many IC's have signals with less than 5 nanoseconds [5000 picoseconds] rise times. Any signal with this speed or faster acts like a transmission line and requires special PCB layout techniques. This means that most of your signal routing should be addressing this phenomenon.
   "Due to faster rise times and increasing interconnect lengths, the electrical length of interconnects becomes a significant fraction of the operating wavelength, and transmission line effects must be taken into account," writes Roshan Weerasekera in his 2008 doctoral thesis on System Interconnection Design Trade-offs in Three-Dimensional (3-D) Integrated Circuits. This statement applies in both IC design and PCB design. What this means for PCB designers is they need to be aware that stackups and routing techniques that routinely worked 30 years ago won't always work today.
   If you get a chance to attend a workshop by a digital design guru on high speed PCBs, take it. You need this knowhow more than you might realize. Or read Henry Ott's book Electromagnetic Compatibility Engineering

R terms index



route — 1. n. A layout or wiring of a connection. 2. v. The action of creating such a wiring.
R terms index



S

TOP



SAC4 — Self-Aligned Controlled Collapse Chip Connect. A variation of C4 flip-chip technology. . PFEIFFER L, WEST KW, WONG YH ,Journal of the Electrochemical Society (JES) Volume 134, Number 11, November 1987.
S terms index



saturation — 1.  The operating condition of a transistor when an increase in base current produces no further increase in collector current.  2.  A circuit condition whereby an increase in the driving or input signal no longer produces a change in the output.  3.  The condition when a transistor is driven so hard that it becomes biased in the forward direction. In a switching application, the charge stored in the base region prevents the transistor from turning off quickly under saturation conditions.  4.  Generally, that state in which a semiconductor device is conducting most heavily for a given applied voltage. In many devices it is also a state in which the normal amplification mechanisms have become "swamped" and inoperative.   [Graf]

S terms index



schematic — A diagram which shows, by means of graphic symbols, the electrical connections, components and functions of an electrical system. The components are represented by agreed-upon symbols, and the conductors connecting them by lines. If two lines cross each other, a large dot represents a junction, whereas no dot represents no connection.
S terms index



short — Short circuit. 1. An abnormal connection of relatively low resistance between two points of a circuit. The result is excess (often damaging) current between these points. Such a connection is considered to have occurred in a printed wiring CAD database or artwork anytime conductors from different nets either touch or come closer than the minimum spacing allowed for the design rules being use.
S terms index



signal — 1. A net. 2. A net other than a power or ground net.
S terms index



silicon wafer — a thin, iridescent, silvery disk of silicon which contains a set of integrated circuits, prior to their being cut free and packaged. A silicon wafer will diffract reflected light into rainbow patterns and, being a similar size, looks so much like a music CD that it could be mistaken for one (except that it has no label or hole in the middle). On closer inspection, one can see the individual (usually rectangular- or square-shaped) integrated circuits which form a uniform patchwork quite unlike the surface of a music CD. When cut or etched from the wafer these circuits are then called chips or dice.

S terms index



silkscreen — (Also called "silkscreen legend")

1. 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, the same technique used in the printing of T-shirts.

A silk mesh size commonly used is 6 mils. With this mesh size, the absolute minimum line width of any silkscreen legend artwork is 6 mils, which leaves a very faint line. 7 mils works better for a practical minimum line width.

Newer silkscreening methods allow for sikscreen draws of 5 mils, which come out very clear. A good reference designator size to use is 35 mils high with a 5 mil draw

2. A Gerber file controlling the photoplotting of this legend.
S terms index



single track — PCB design with only one route between adjacent DIP pins.
S terms index



SMD — 1.  Surface Mount Device (SMT component).  2.  Solder-Mask Defined



SMT — Surface Mount Technology.
S terms index



soft — Pertaining to or consisting of software.
S terms index



soft copy — An electronic form of a document; a data file in computer memory or stored on storage media. When one is looking at a soft copy he is viewing the document as displayed on a computer monitor.



software — Programs, data files, procedures, rules, and any associated documentation pertaining to the operation of a computer system or of a computer application.
S terms index



solder balls — The round solder balls bonded to a transistor contact area and used to make connection to a conductor by face-down bonding techniques.

In IBM's ceramic BGA's, the solder used in solder balls has a higher melting point than that used in soldering the ball to the chip substrate and the BGA to a board. IBM uses 10/90 tin/lead for the solder ball and eutectic solder for the assembly. The high melt balls of the BGA do not melt during PCB assembly and thus create a pre-determined standoff height for the component.
PBGA packages use a eutectic solder ball which provides a collapsible joint similar to C4.
[Source:   IBM Ceramic Ball Grid Array Surface Mount Assembly and Rework]

S terms index



solder bumps — solder balls.
S terms index



solder mask — A technique wherein everything on a circuit board is coated with a plastic except 1) the contacts to be soldered, 2) the gold-plated terminals of any card-edge connectors and 3)fiducial marks.
S terms index



space transformer — Abbreviated ST. A major component of certain high-density probe cards. It provides pitch reduction, high routing density and localized mid-frequency decoupling.  A major developer of ATE systems which use space transformers is Wentworth Labs.

S terms index



sputtering — A deposition process wherein a surface, or target, is immersed in an inert-gas plasma and is bombarded by ionized molecules that eject surface atoms. The process is based on the disintegration of the target material under ion bombardment. Atoms broken away from the target material by gas ions deposit on the part (substrate), forming a thin film.   [Graf]

S terms index



SQFP — Shrink Quad Flat Pack. See QFP.

S terms index



ST Space Transformer.

S terms index



stable datum — a datum along which all other data align. From any confusion, order and sanity can emerge providing one merely selects a datum, assigns it importance or seniority and then begins to align other data against it.

The stable datum for any PCB layout could be stated this way:  The schematic is the "Bible." In other word, the schematic says the circuit is this way, and the PCB design must follow that pattern perfectly.
S terms index



stack-up — The arrangement of layers of materials in the construction of a PCB. The individual layers can be of various thicknesses.

Most commonly, rigid PCBs are 1/16 inch [1.5875 mm] thick in total. This is the thickness of "cards" you can add to your desktop computer. There is a tolerance on this overall 1/16th inch thickness of plus or minus 10%. Of course, PCBs can be thinner or thicker based on the end use for which they are intended.

In the case of the computer card, if the card has a lot of electronic power, such as a gamer's video card, it will be physically large. But also, it will have more layers than a simple Wi-Fi card. Needing to remain 1/16th inch thick [62.5 mils or 1.5875 mm], the layers will be thinner. Especially the center layer.

At the center layer of a PCB stack-up is a core (q.v.). The rest of the layers we can call "outer" layers. These are made thin. The best practice is to keep the outer dielectrics at 4 mils [102 microns] to 8 mils [204 microns] thickness. The use of thin outer layers has to do with electromagnetic compatibility (EMC).

EMC side-note: Thin layers help in electromagnetic field containment when layers with signal wires are sandwiched between ground planes. The thin layers of dielectric between the conducting layers means the electromagnetic fields (EM fields) set up between the signals and ground plane will be small. The smaller the EM fields, the less noise is generated by electromagnetic interference (EMI). This is fundamental to improving EMC.

The core at the center, being a slab of dielectric with layers of copper on top and bottom, provides the two inner-most layers of copper and enough dielectric thickness to make up the difference between the thickness of all the other materials and the 1/16th inch thickness of the card. This provides rigidity. If the core were too thin, the card would be flimsy and not fit snuggly into the motherboard connector. If the core were too thick, the card wouldn't fit at all. And all this might be more than you wanted to know about PCB stack-up. If you're a printed circuit designer, you already know all this. If not, I probably lost you a long time ago.

Stack-up 10 layers in CAD 3D perspective showing thick center core

St

Stack-up 6 layers in CAD 3D perspective showing even thickec center core

If the layers are reduced from 10 to 6, the center core must be thicker to maintain the overall thickness of 1/16th inch.



Streamlined Design — See Streamlined PCB Design

S terms index



Streamlined PCB Design — Streamline— v.  Cause to be quick and efficient. Streamlined design = accuracy plus speed. Streamlined PCB Design, or SLPD, is a set of policies that guide John Childers' design of printed circuit boards. The policies have been derived with the aim of simplifying and systematically eliminating errors from PCB design.
S terms index



stuff Slang Populate. Attach and solder components to (a printed wiring board ).

S terms index



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. The tabs are strong enough so that the sub-panel can be assembled as a unit, and weak enough so that final separation of assembled modules is easily done.



substrate — The supporting material on or in which the parts of an integrated circuit are attached or made. The substrate may be passive ( thin film , hybrid ) or active ( monolithic compatible). [For more information see Modern Dictionary of Electronics, by Rudolf F. Graf.]

S terms index



surface mount — Surface mount technology. The technology of creating printed wiring wherein components are soldered to the board without using holes. The result is higher component density, allowing smaller PWB 's. Abbreviated SMT.
S terms index



symbol — A simplified design representing a part in a schematic circuit diagram.
S terms index



      

T

TOP



TAB — Tape Automated Bonding.
T terms index



tented via — a via with dry film solder mask completely covering both its pad and its plated-thru hole. This completely insulates the via from foreign objects, thus protecting against accidental shorts, but it also renders the via unusable as a test point. Sometimes vias are tented on the top side of the board and left uncovered on the bottom side to permit probing from that side only with a test fixture.
T terms index



TDR — Time Domain Reflectometer, a device which a board house can use for measuring characteristic impedance of a conductor on a printed board, thus insuring an accurate build for controlled impedance.
T terms index



terminal — A point of connection for two or more conductors in an electrical circuit; one of the conductors is usually an electrical contact, lead or electrode of a component.
T terms index



terminal block — a type of header to which wires are attached directly instead of by means of a connector plug. Each wire is inserted in a hole in the terminal block , and then anchored by means of a screw.
T terms index



test coupon — An area of patterns and holes located on the same fabrication panel as the actual PCB, but separate from the electrical circuits and outside the board outline(s). It is designed to reflect the technology used on the PCB, such as smallest plated-through hole size, any blind or buried vias, etc. It is cut away from the panel and can be embedded in a clear plastic to prepare it for destructive testing.

T terms index



thin film — A film of conductive or insulating material, usually deposited by sputtering or evaporation, that may be made in a pattern to form electronic components and conductors on a substrate or used as insulation between successive layers of components.   [Graf]

T terms index



through-hole — (Of a component, also spelled "thru-hole"). Having pins designed to be inserted into holes and soldered to pads on a printed board. Contrast with surface mount.

T terms index



thru-hole — Same as through-hole.

T terms index



TQFP — Thin Quad Flat Pack. Essentially the same as a QFP except low-profile, that is, thinner.
T terms index



trace — Segment of a route.

T terms index



track Trace.

T terms index



Trillium — A company that makes DUT or ATE systems.

T terms index



TTL — Transistor-Transistor Logic. Also called multiple-emitter transistor logic.  A widely used form of semiconductor logic. Its basic logic element is a multiple-emitter transistor. TTL is characterized by fairly high speed and medium power dissipation.   [Graf]

T terms index



      

U

TOP



UL — Underwriter's Laboratories, Inc., a corporation supported by some underwriters for the purpose of establishing safety standards on types of equipment or components.

U terms index



unsaturated logic — A form of logic containing transistors operated outside the region of saturation , which makes for very fast switching.  An example is emitter-coupled logic ( ECL ).  (For other definitions and examples see [Graf] .)

U terms index



unstuffed Slang - PCB Manufacturing Not populated.

U terms index



US-ASCII — The 7-bit (using character codes 0-127) version of ASCII , which preceded (and is the basis for) 8-bit versions such as Latin-1, MacASCII and later, even larger coded character sets such as Unicode.



      

V

TOP



Valuable Final Artwork — A term used in " Streamlined_PCB_Design :"   Artwork for electronic circuits which have been laid out and documented in forms perfectly suited to the photo-imaging and numeric-controlled tooling processes of printed circuit manufacture. It is termed "final" because it has been thoroughly checked for errors and any corrected as needed and is now ready for manufacture without further work by the PCB designer. It is valuable because it could be exchanged with a customer for money or other support. Abbr. VFA. [Based on " Valuable Final Product."

V terms index


Valuable Final Product — Something that can be exchanged with other activities in return for support. The support usually adds up to food, clothing, shelter, money, tolerance and cooperation (goodwill).... A valuable final product (VFP) is valuable because it is potentially or factually exchangeable. The key word in this sense is EXCHANGEABLE. And exchangeability means outside, with something outside the person or activity. A valuable final product could as easily be named a VALVABLE EXCHANGEABLE PRODVCT. [L. Ron Hubbard, March 25, 1971, "Valuable Final Products."]

V terms index



vcc or VCC or Vcc — A name for a power net meaning "voltage collector," usually +5V for TTL circuits.

V terms index



vdd or VDD or Vdd — A name for a power net meaning "voltage drain," usually implying a more positive voltage.
V terms index



vector photoplotter — (also "vector plotter", or "Gerber photoplotter" after Gerber Scientific Co., which built the first vector photoplotters for commercial use)  It plots images from a CAD database on photographic film in a darkroom by drawing each line with a continuous lamp shined through an annular-ring aperture, and creating each shape (or pad) by flashing the lamp through a specially sized and shaped aperture. The "apertures" are thin trapezoidal pieces of plastic which are mostly opaque, but with a transparent portion that controls the size and shape of the light pattern passing through it. The apertures are mounted on an " aperture wheel " which can hold up to 24 apertures (or 70 on certain models). The lamp and aperture wheel are fixed, and the table holding the film is moved in x and y dimensions (on small photoplotters), or vice versa (on very large photoplotters). A numeric datum sent to the control circuit of the photoplotter is either a D code or an X and/or Y dimension in inches, to the nearest thousandth. If it is a D code equal to D10 or above, the message tells the wheel to rotate the corresponding aperture location into position in front of the lamp. .  Gerber photoplotters, if set up by an experienced craftsman, are well-suited for printed circuit artwork generation. Compare with laser photoplotter , which is faster, more accurate and has largely replaced the vector photoplotter.

There are still vector photoplotters in use. Some manufacturers take advantage of the large bed size of the largest Gerber photoplotters, roughly the size of a full-sized billiards table. This enables the production of very large photoplots. An example is Buckbee-Mears, which makes large antenna boards, and the USGS (United States Geological Survey) which has used them in map-making.


V terms index

vee or VEE or Vee — A name for a power net meaning "voltage emitter," usually -5V for ECL circuits.

V terms index



via — Feed-through. A plated-through hole in a PWB used to route a trace vertically in the board, that is, from one layer to another.

V terms index



VLSI — Very Large Scale Integration.

V terms index



VQFP — Very thin Quad Flat Pack.



vss or VSS or Vss — A name for a power net meaning "voltage source," usually implying a more negative voltage and often equivalent to Ground or GND.
V terms index



      

W

TOP



wafer — See silicon wafer.

W terms index



WIP — Work In Progress.   [Usage at Golden Gate Graphics: wip is used as the extension of the name of a folder or sub-directory which groups data in temporary storage locations for current "work in progress."  Any folders beneath the .WIP folder in the directory structure would be named for the software, company and job in that order. Eg: pclayout.wip/Cadstar/AcmeInc/A2Dboard ]
W terms index



wire bonding — The method used to attach very fine wire to semiconductor components ( dice ) to interconnect these components with each other or with package leads.  The wires might be 1 to 2 mils in diameter and made of aluminum containing 1% silicon.
W terms index



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. Therefore, it has been obsolete for decades.
W terms index



wire — Besides its usual definition of a strand of conductor, wire on a printed board also means a route or track.



wire wrap area — A portion of a board riddled with plated-through holes on a 100-mil grid. Its purpose is for accepting circuits which may be found necessary after a PWB has been manufactured, stuffed , tested and debugged.

W terms index



      

X

TOP



      

Y

TOP



      

Z

TOP

TOP

Example Printed Boards

Click for Examples of PCBs designed by Golden Gate Graphics



References and Dictionaries

Modern Dictionary of Electronics by Rudolf F. Graf

This is the best, most usable dictionary for electronics, because its definitions help you grasp the terms and therefore the subject. Lesser dictionaries define electronics terms with even more difficult technical jargon, leading one into endless "word chains." Not this one.
You can buy the Modern Dictionary of Electronics new or used via the Internet.

Citation:
Graf, Rudolf F. Modern Dictionary of Electronics. Newnes, 1999.


The Random House Dictionary of the English Language, Unabridged, 2nd Edition

You need a big, comprehensive dictionary. Get this one. Despite being a big dictionary, The Random House has great definitions, quick to grasp.

Although out of print, as of 2020 you could still buy a great used copy online for $30 including shipping or possibly for much less. Two versions are available of the 2nd Edition, Unabridged:

I have no idea what the difference is for the deluxe edition, but there seem to be fewer copies of it available in 2020 than the regular edition. I'm sure they both have the same set of definitions. My copy has both ISBNs listed in the front matter, and it is the regular edition.

Citation:
Flexner, Stuart Berg, and Leonore Crary Hauck, editors. The Random House Dictionary of the English Language. Unabridged, 2nd Edition, Random House, 1987.

TOP