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GLOSSARY of Printed Circuits

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

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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.

TOP       E

Index to terms on this page:

E-pad   ECL  
electrical object   embedded   EMC   emitter   EMP   ENIG   end-to-end design   EP   Excellon  

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.
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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]
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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.
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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.
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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.
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emitter — An electrode on a transistor from which a flow of electrons or holes enters the region between the electrodes. [Random House]
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EMP — Electromagnetic pulse. A reaction of large magnitude resulting from the detonation of nuclear weapons. [Graf]
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ENIG — (EE-nig)  Pronunciation Key  noun  [PCB Manufacturing]  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.
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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
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EP — (EE-PEE)  Pronunciation Key  noun  [PCB Components] Exposed Paddle (aka exposed DAP, q.v.). Also called external paddle. A thermal pad located under a component; it should have a land on the PWB to solder it to. Very common in no-lead components like DFNs and QFNs.
On the PCB, vias should be placed in this exposed pad and connected to ground as an effective heat sink. Of course, if this die paddle is connected within the IC (integrated circuit) to some potential other than ground (rare), connect this pad and the vias to that potential instead of ground. If this die attached paddle is floating (not connected electrically to anything in the IC), the pad and the vias should be connected to ground.
   In PCB design layout of an EP footprint, the solder paste artwork should not be one large rectangle: It should be several small rectangles. This configuration has acquired the slang term "window pane" or "window paning." The term applies to the pattern, whether in the CAD file, the artwork or the solder paste stencil. Window paning prevents too large an amount of solder building up under the EP and floating the package far enough off the PWB that some of the signal lands do not get solder, causing opens. See via and solder paste examples in Application Report - QFN/SON PCB Attachment, especially the topic "Solder Paste Screen Printing Process" and "Figure 11. Example Land Pattern and Exposed-Pad Stencil Design"
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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.
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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.

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.

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