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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       M

Index to terms on this page:

Manhattan algorithm  
Manhattan length  
master aperture list   MCR   MELF   MIC  
micro ball grid array  
micro BGA   mil   MLC   monolithic  
monolithic integrated circuit   MSOP   MTF   mullite   multimeter  

Manhattan algorithm — An algorithm to determine a cross street for an avenue address in Midtown Manhattan New York City, or for the length of a trip from one address in Manhattan to another. If you know the building addresses for where you are and where you want to go in Manhattan, you can call a cab company and find out what it will cost you. An algorithm is used to get the answer, because in Manhattan the street and avenue numbers do not necessarily correspond intuitively to the building numbers. To see an example of the Manhattan algorithm as an intersection locator, go to What does this have to do with PCB design? The Manhattan algorithm has many variations and uses in various branches of mathematics, including the mathematics of auto-routers.  See also Manhattan length.

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Manhattan length — The length of the two sides of a right triangle as a distance between two points, as opposed to the hypotenuse.. (Derived from the Manhattan algorithm for determining the length of a taxicab trip following streets and avenues on the island of Manhattan, NY.)  Routing of traces in orthagonal patterns in a PCB design, or in a semiconductor chip, follows the same pattern as streets and avenues in a city.  The minimum distance between two component leads, or two nodes on a chip, when routing on 90 degrees is the Manhattan length .

 Advanced PCB auto-routers permit specification of maximum length of classes of nets as a percentage of Manhattan length . For example, one could specify clocks as 120% and random nets as 160% of Manhattan length . (This percentage, expressed as a ratio, becomes the "Manhattan coefficient", ie. a Manhattan coefficient of 1.2 means the routed length is 120% of the Manhatten length .) Specifying such limits on the auto-router prevents long and circuitous routes.
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master aperture list — 1. An aperture list which is used for every PCB designed by a PCB design service bureau or department.  If a new design requires one or more new apertures, they are added to the list, either at the end or in some previously unused positions set aside for that purpose. The previously used aperture positions are never edited to change their parameters. Thus the updated list can still be used as a master for any previous PCB's designed. This type of master aperture list became possible only with the advent of laser photoplotters , which can have upwards of 1000 positions if need be.  2. Any aperture list which is used with two or more PCB's would be called the master aperture list for that set of PCB's.
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MCR — Molded Carrier Ring. A type of fine-pitch chip package named for the method of supporting and protecting the leads. The leads are left straight; the ends of the leads are embedded in a strip of plastic, which is the Molded Carrier Ring. Just before assembly (placing on a PCB for soldering), the MCR is cut off and the leads are formed. In this way, the delicate leads are protected against damage in handling until just before assembly.
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MELF — Metal ELectrical Face - A surface mount discrete part, usually a diode, that is barrel shaped, or cylindrical. The ends of the "barrel" are capped with metal, the "metal electrical face." The "barrel" is laid on its side, the metal ends upon landing pads, and the part is soldered that way. The two most common sizes are MLL34 and MLL41, which are roughly MELF versions of a DO-35 and DO-41 respectively.
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MIC Monolithic Integrated Circuit.

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micro ball grid array — A fine pitch ball grid array. Fine pitch for BGAs is anything equal to or less than 0.5 mm [19.7 mil ]. In practice, a micro-BGA is one that is so dense, it requires controlled-depth laser-drilled blind microvia-in-pad technology.
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micro-BGA micro Ball Grid Array.

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mil — One thousandth of an inch [0.0254 mm] [From shortening of milli-inch, which means one-thousandth of an inch.]
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MLC — Multi-Layer Ceramic.
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monolithic — 1.  Existing as one large, undifferentiated whole.  2.  (of an integrated circuit or its elements) built upon or formed within a single slice of silicon substrate.
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monolithic integrated circuit — 1.  Abbreviated MIC. An integrated circuit formed upon or within a semiconductor substrate with at least one of the circuit elements formed within the substrate.    2.  A complete electronic circuit fabricated as an inseparable assembly of circuit elements in a single small structure. It cannot be divided without permanently destroying its intended electronic function.   [Graf]

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MSOP — (IM-sop)  Pronunciation Key  noun  [PCB Components] Micro (or Mini) Small Outline Package. This is a surface-mount package with a dual in-line arrangement of pins.
   Maxim calls this a uMax or uSop (where the u stands for the Greek letter "Mu"). These are similar to TSSOP's, but have narrower bodies.
   The acronym does not define the lead pitch. Some MSOPs have 0.5mm and others have 0.65mm pitch.
   The acronym is insufficient to define the part—you MUST consult the spec sheet's mechanical drawing in order to build an accurate footprint. Followed by a number, with or without an intervening hyphen, it roughly defines the package (somtimes it is used with the number followed by the acronym. For example, MSOP8, MSOP-8 or 8MSOP is an 8-lead device.

MSOP8 simple 3D body

The picture shows a simple 3D body MSOP8_SOP65P490X110-8N (John Childers' library part naming scheme starts with a commonly-used acronym followed by an IPC naming convention. This way, I can search my footprint library on MSOP to find the footprint. The IPC-7351B naming convention doesn't include an intuitive string to search on.)
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MTF — Multi-layer Thin Film.

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mullite — A substrate compound of alumina and silica (3Al 2 O 3 •2SiO 2 ).

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multimeter — A portable test instrument which can be used to measure voltage, current, and resistance.
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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.