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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       R

Index to terms on this page:

ratsnest  
reference designator  register   registration   RF  
rise time   route  



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 Snest.)

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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.

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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!"]

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registration — See register.

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RF — Radio Frequency.

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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

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route — 1. noun A layout or wiring of a connection. 2. verb The action of creating such a wiring.

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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.

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.

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