GLOSSARY of Printed Circuits

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Index to terms on this page:

AABUS   ablation   ABS   active component   active heatsink   additive electronics   additive manufacturing   AFE   air   ALD   ALN   Altera Corporation   alumina   AMQP   analog circuit   anode   ANT   antipad   AOI   A1   aperture  
aperture list   aperture table  
aperture wheel   ARM   ARP   artwork   ASCII   ASCII text   aspect ratio   assembler   assemble   assembly   assembly drawing   assembly house   assembly pallet   ASTM   AT cut   ATC   ATE   atomic transaction   A2   auto-escaping   autoescape   autorouter   AWG  

AABUS — As Agreed Upon Between User and Supplier

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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.
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ABS — noun  [Plastics]  acrylonitrile-butadiene-styrene - any of a class of composite plastics used to make car bodies and cases for computers and other appliances
"Acrylonitrile-butadiene-styrene - Definition of Acrylonitrile-butadiene-styrene by the Free Online Dictionary, Thesaurus and Encyclopedia." Dictionary, Encyclopedia and Thesaurus - The Free Dictionary. Farlex, Inc., 2011. Web. 04 Nov. 2011. &Acrylonitrile-Butadiene-Styrene

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

1. noun [Electronics] A component which adds energy to the signal it passes.
       
 
2. noun [Electronics] A device that requires an external source of power to operate upon its input signal(s).
       
 
3. 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.)   

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.

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additive electronics — additive manufacturing for printed electronics. See also additive manufacturing.

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additive manufacturing — aka 3D printing. Unlike subtractive manufacturing methods that start with a solid block of material and then cut away the excess to create a finished part, additive manufacturing builds up a part (or features onto parts) layer by layer from geometry described in a 3D design model. additive manufacturing.
Notes:
Applications include garments.
CAD tools are essential in the design process. Autodesk has been adapted for this by scientists.

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

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air — gap spacing or clearance. Air gap is found in UL specifications regarding clearance between conductors with high voltage differential.

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ALD — Ambient Light Detector

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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.

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Altera Corporation — A Silicon Valley manufacturer of PLDs, reconfigurable complex digital circuits. The company released its first PLD in 1984. Altera's main products are the Stratix, Arria and Cyclone series FPGAs,[1] the MAX series CPLDs (Complex programmable logic devices), the HardCopy series ASICs and Quartus II design software. Wikipedia.Altera

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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 )
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AMQP — Advanced Message Queuing Protocol 1.0 approved as an International Standard. International Standard (ISO/IEC 19464) Advanced Message Queuing Protocol Goal: A platform agnostic message protocol.

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analog circuit — A circuit in which the output varies as a continuous function of the input, as contrasted with digital circuit.
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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. 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. Modern Dictionary of Electronics. Newnes, 1999]

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.

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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.

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. 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.   
 
3. 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.   

AOI — PCB manufacturing Automatic Optical Inspection

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A1 — see Relay Coil Terminals A1 and A2

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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. noun [Photoplotting] A print-out of this file.
       
 
3. noun [Photoplotting] A binary version of this file. [Also called "aperture table."]
       

aperture table — See aperture list.
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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.

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

In 2013, Altera Corporation began shipping the first of its 28 nm Cyclone V SoC devices, which combine a dual-core ARM Cortex-A9 processor system with FPGA logic on a single chip.

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ARP — Address Resolution Protocol. The Address Resolution Protocol (ARP) is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function in the Internet protocol suite.

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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.
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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.

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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.
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assemble —

1. verb  [PCB Manufacturing]  Attach and solder components to a PCB.
2. verb  [PCB Manufacturing]  Manufacture a completed electronic product, including
   • the PCB with components attached and soldered,
   • additional parts such as a brackets, standoffs and other hardware attached mechanically,
   • additional PCBs if any,
   • the case (aka enclosure) and
   • cables with connectors.

assembler — An assembly house. Aka "CM" for Contract Manufacturer. An assembler is the manufacturer of an assembled or populated or "stuffed" PCB. An assembled PCB, aka a PCBA (PCB Assembly), is a PCB with all components attached and soldered as needed.

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assembly —

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

aspect ratio — The length of a hole divided by its width before plating (with drilled holes, that is the width of the bit). This is a limiting factor in the minimum diameter of drilled via holes. Any board house will be able to tell you what its maximum aspect ratio is for drilled holes, and thus the minimum via bit size for a board of specified thickness. Many board houses can handle a maximum aspect ratio of 10:1. Some board houses can go higher, some can't get up to 10:1. Higher than 10:1 will usually cost more.

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assembly drawing — A drawing depicting the locations of components, with their reference designators , on a printed circuit. Also called "component locator drawing."
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assembly house — A manufacturing facility for attaching and soldering components to a printed circuit. Aka assembler and also CM, for contract manufacturer.

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assembly pallet — A portion of a PCB fabrication panel (q. v.). "Assembly pallet" is the term used by assembly house personnel. Board house personnel tend to call this a "sub-panel." An assembly pallet has handling rails, which have features such as fiducials and tooling holes. An assembly pallet is created at the board house with all the features needed. It is the assembly house that specifies the details of such features. One of the final steps of bare board fabrication is to separate the assembly pallets from the PCB fabrication panel. These are then sent to the assembly house where components are attached and soldered.
An assembly pallet will usually consist of two or more printed circuit boards. The use of a pallet assists in the handling during assembly of a group of printed circuit boards, all of which have their components loaded and soldered in one pass through the assembly line. This is much more efficient than trying to handle very small PCBs one at a time. After assembly the assembly house will either ship the pallet with components attached, or separate it into individual PCBAs.
A large PCB, if rectangular in shape, won't usually require the use of an assembly pallet.
An irregular shaped PCB will usually be fabricated in an assembly pallet in order to assist the handling of it during assembly. Depending on the size of the PCB, the pallet might consist of just one PCB or more than one.

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ASTM — American Society of Testing and Materials.   http://www.astm.org/index.shtml
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AT cut — (AY-TEE-KUT)  Pronunciation Key  noun  [Crystallography] (Of piezoelectric crystals) One of the designations for the orientation of the piezoelectric crystal plate with respect to the axes of the crystal.
The AT cut results in a crystal with stable resonant frequency at or close to room temperature. For a high temperature environment, stress-compensated (SC) crystals are available with a special cut that minimizes the frequency changes due to temperature gradients. [Graf, Rudolf F. Modern Dictionary of Electronics. Newnes, 1999]

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ATC — (AY-TEE-SEE)   Pronunciation Key   noun  [Physical Testing] Accelerated Thermal Cycle (or Cycling), a product reliability test.
Accelerated thermal cycling is accomplished by raising and lowering the temperature of a test object to extremes and more rapidly than would be found in nature or industrial environments. An example: Accelerated Thermal Cycling (ATC) could be carried out between 0˚C and 100˚C with 10 minute ramps, a 10 minute cold dwell and 10-minute hot dwell or 60-minute hot dwell. Test frequencies could be 16 and 36 cycles/day for the 60-minute and 10-minute dwell test profiles respectively. Clech_Jean-Paul_AFTCTELA_EPSI_2005
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ATE — Automatic Test Equipment. (See also DUT.) .

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atomic transaction — [Apache Subversion] A Subversion client commits (that is, communicates the changes made to) any number of files and directories as a single atomic transaction. By atomic transaction, we mean simply this: either all of the changes are accepted into the repository, or none of them is. Subversion tries to retain this atomicity in the face of program crashes, system crashes, network problems, and other users' actions.

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A2 — see Relay Coil Terminals A1 and A2

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auto-escaping — See autoescape.

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autoescape — [Software] A feature in a software script or program that automatically converts all common HTML tag or other special programming characters by means of HTML escaping, q.v.

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autorouter — automatic router, a computer program that routes a PC board design (or a silicon chip design) automatically.

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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.

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