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GLOSSARY of Printed Circuits

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

   SYMBOLS    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

Formerly known as

GLOSSARY of Printed Circuit Design and Manufacturing

This glossary has key terminology in use in PCB design and manufacturing, with a smattering of electronics. The definitions were chosen so that their context would likely apply to reading material encountered by a PCB designer. Therefore, many of these terms will have other meanings not given here. See recommended dictionaries below.

This collection of terms came about as I, a PCB designer, ran across words and acronyms in my field for which meanings were hard to find. As I tracked them down, I made them part of this glossary. If you are a PCB designer, then this glossary could be a good place to start when you find a need to look up the meanings of words related to printed circuits or electronics.

TOP       O

Index to terms on this page:

odd-mode impedance   OE   OEM   OLED   open   OR  
ordinate dimension   OSI model   OSP   OTTP   ounce  

OASIS — The Organization for the Advancement of Structured Information Standards (OASIS) is a global nonprofit consortium that works on the development, convergence, and adoption of open standards for security, Internet of Things, energy, content technologies, emergency management, and other areas.
Under its committee category IoT/M2M, there is a technical commmittee for OASIS Advanced Message Queuing Protocol (AMQP).

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  1. Overtaken By Events
  2. Our Best Estimate
  3. Our Best Effort
  4. Out-Board Electronics
  5. Overwhelmed by Events

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ODB++ — ODB stands for Open Data Base.

ODB++ is a PCB fabrication data exchange format in ASCII that goes beyond Gerber and NC DRill data to describe the fully assembled PCB, with all constituent parts. Developed by Valor, it branched into IPC-2581 (later given the acronym DPMX, which means Digital Product Model eXchange) in 2011.
Wikipedia ODB++

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ODBC — Open DataBase Connectivity. (Refers to industry-standard framework.)

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odd-mode impedance — One-half the differential impedance.

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OE — Output Enable

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OEM — Original Equipment Manufacturer

  1. ( company that puts together computer systems using pieces of equipment bought from other companies, and sells them under its own name.
  2. ( A company that has a special relationship with computer producers: OEMs buy computers in bulk and customize them for a particular application; then they sell the customized computer under their own name. The term is really a misnomer because OEMs are not the original manufacturers; they are customizers of other people's products.

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OLED — Organic Light Emitting Diode

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open — (OH-pən)   Pronunciation Key  noun  [Electrical Circuits] Open circuit. An unwanted break in the continuity of an electrical circuit which prevents current from flowing.

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OR — OR gate. A two-input Boolean circuit that has a value of 1 (or true) if either of its inputs is 1 (that is to say, high voltage).

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A truth table for an OR gate is shown below:
Input A Input B Output
0 0 0
0 1 1
1 0 1
1 1 1

This shows that if either or both inputs are 1, the output is 1. Both have to be 0 for the output to be 0.

ordinate dimension — Altium Designer 18.0 and later. Same as term used in earlier Altium Designer releases: datum dimension, q.v.

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OSI model — The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard protocols. The model partitions a communication system into abstraction layers. The original version of the model defined seven layers.

A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that comprise the contents of that path. Two instances at the same layer are visualized as connected by a horizontal connection in that layer. The model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO). Wikipedia OSI model

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OSP — Organic Solder Preservative (Protective). A coating used on exposed copper on a PCB to preserve the copper from oxidation until it can be soldered. This is an alternative to metallic finishes such as solder coating, gold or silver plating. OSP has a short shelf-life (6-months, avoid physical contact) compared with some metallic finishes, so a PCB so finished should be assembled as soon as possible. Note: Immersion Silver and Immersion Tin also have 6-months shelf life, avoid physical contact. [IPC D_7251WD1 Table 3-27]

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OTTP — Open Trade Transfer Package format. A structure that allows files to be generated to facilitate the exchange of data concerning trade. It can be utilized to exchange information on product specifications, requirements, defaults and restrictions as well as capabilities. It can also be used to exchange a material list or other needed related data.

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ounce — (OWNS)  Pronunciation Key  modifier  [PCB Manufacturing] A unit used to specify thickness in terms of copper weight on a PCB, as in "1-ounce copper" or "Half-ounce copper."
   This is actually PCB manufacturing slang. Ounce is a shortening of "ounces per square inch." Because copper has a characteristic density, this is a thickness unit, not a weight unit. I hope that clears up something for those new to our industry. For actual thickness of "1-ounce copper", see copper weight.

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Alphabetizing Method

Terms that begin with a symbol or a digit are placed in the SYMBOLS page. Terms that contain digits within them 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 (/), dash (-) or plus sign (+), these are treated the same as spaces and ignored for the purpose of alphabetizing.

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 2022 you could still buy a great used copy online for $40 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.

Golden Gate Graphics in an official Altium Service Bureau
Golden Gate Graphics is an official Altium Service Bureau