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PCB Technology

Glossary and Abbreviations - PCB Glossary

Click on an alphabet below to directly jump to the chosen alphabet section...


Alphabet A

  • ActivatingA treatment that renders non-conductive material receptive to electroless deposition.
  • Active componentA device that requires an external source of power to operate upon its input signal(s). Examples of active devices: transistors, rectifiers, diodes, amplifiers, oscillators, mechanical relays.
  • Additive ProcessDeposition or addition of conductive material on clad or unclad base material.
  • AlNAluminum Nitride, a compound of aluminum with nitrogen.
  • AlN SubstrateA substrate of aluminum nitride.
  • Air gapThe minimum distance between features pad - pad, pad – traces and trace – trace
  • AluminaA ceramic used for insulators in electron tubes or substrates in thin film circuits. It can withstand continuously with high temperatures and has a low dielectric loss over a wide frequency range. Aluminum oxide (Al2O3)
  • AmbientThe surrounding environment coming into contact with the system or component in question Annular Ring: The width of the conductor pad surrounding a drilled hole. The pad area that remains after a hole is drilled through the pad. Designer tip: Try using teardrop shaped pads. They allow for any drill wander and / or Image shift during manufacturing and will help keep a healthy (over .002") annular ring, at trace junction (required by IPC: A: 600).
  • Analog CircuitAn electrical circuit that provides a continuous quantitative output as a response from its input.
  • ApertureAn 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.
  • Aperture wheelA component of a vector photoplotter, it is a metal disk having cutouts 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 retrieved 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 photo plotting, 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 photoplotter as compared with laser photoplotter.
  • Aperture InformationThis is a text file describing the size and shape of each element on the board. Also known as a D:code list. This report is not necessary if your files are saved as Extended Gerber with embedded Apertures (RS274X).
  • ApertureList/ApertureTableA list of the shapes and sizes for describing the pads and tracks used to create a layer of a circuit board. Assembly File: A drawing describing the locations of components on a PCB.
  • AOI(Automated Optical Inspection): Automatic laser/video inspection of traces and pads on the surface of inner layer cores or outer layer panels. The machine uses cam data to verify copper feature positioning, size and shape. Instrumental in locating "open" traces, missing features or "shorts".
  • AQL(Acceptance Quality Level): The maximum number of defectives likely to exist within a population (lot) that can be considered to be contractually tolerable, normally associated with statistically derived sampling plans.
  • ArrayA group of elements or circuits arranged in rows and columns on a base material.
  • Artwork MasterThe photographic image of the PCB pattern on film used to produce the circuit board, usually on a 1:1 scale.
  • Aspect RatioThe ratio of the PCB thickness to the diameter of the smallest hole.The ratio of the board thickness to the smallest drilled hole. (Ex. 0.062” thick board 0.0135” drill = aspect ratio of 4.59:1). Designer tip: Minimizing the aspect ratio of the holes improves through hole plating and minimizes the chance of via failures.
  • ArtworkArtwork 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.
  • ASCIIAmerican Standard Code for Information Interchange. ASCII is the basis of character sets used in almost all present day computers.
  • AssemblyThe process of positioning and soldering components to a PCB. 2. Act or process of fitting together parts to make a9+ whole.
  • Assembly drawingA drawing depicting the locations of components, with their reference designators, on a printed circuit. Also called "component locator drawing."
  • Assembly houseA manufacturing facility for attaching and soldering components to a printed circuit.
  • ASTMAmerican Society of Testing and Materials.
  • AWGAmerican Wire Gauge. A PCB Designer needs to know diameters of wire gauges to properly size Epads. The American Wire Gauge, formerly known as the Brown and Sharp (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.
  • Automated Test Equipment (ATE)Equipment that automatically test and analyzes functional parameters to evaluate performance of the tested electronic devices.
  • Automatic component placementMachines are used to automate component placement. High-speed component placement machines, known as chip shooters, place the smaller, lower pin count components. More complex components with higher pin counts are placed by fine pitch machines that have greater precision.
  • Automatic optical component inspectionPost placement optical inspection of component presence/absence using automated systems.
  • Automatic X-Ray component/pin inspectionThese inspection machines use X-Ray images to look under components are inside of the joints to determine the structural integrity of the solder connections.
  • AutorouterAutomatic router, a computer program that routes a PC board design (or a silicon chip design) automatically.
  • ArrayA group of elements or circuits (or circuit boards) arranged in rows and columns on a base material.

PCB Design Tips

When designing a PCB, try to limit the amount of draws you use. Draws use a lot of memory and slow the programming time. Use a flash for pads instead.

More tips...
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