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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.


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Index to terms on this page:


ball grid array  
ball pitch   ball-pitch   base  
beam lead   BGA   bias   board  
board house   body   BOM  



ball grid array — () (Abbrev. BGA).   A flip-chip type of package in which the internal die terminals form a grid-style array, and are in contact with solder balls ( solder bumps ), which carry the electrical connection to the outside of the package. The PCB footprint will have round landing pads to which the solder balls will be soldered when the package and PCB are heated in a reflow oven. Advantages of the ball grid array package are (1) that its size is compact and (2) its leads do not get damaged in handling (unlike the formed "gull-wing" leads of a QFP ') and thus has a long shelf life. Disadvantages of the BGA are 1) they, or their solder joints, are subject to stress-related failure. For example, the intense vibration of rocket-powered space vehicles can pop them right off the PCB, 2) they can not be hand-soldered (they require a reflow oven), making first-article prototypes a bit more expensive to stuff , 3) except for the outer rows, the solder joints can not be visually inspected and 4) they are difficult to rework.
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ball pitch — (BOL-pich)  Pronunciation Key  noun  [PCB Components] The distance between the centers of adjacent balls in a row or column of a BGA (Ball Grid Array). This will usually be a constant quantity throughout the BGA. (If only this were always, not just usually, the case.)
Ball pitch will be stated in any generic description of a BGA that has leads of consistent pitch. (Eg: a 1-mm BGA256 means a Ball Grid Array with 256 balls arranged in a quadrangular pattern with a pitch of 1 millimeter.) Ball pitch is fixed by the component manufacuturer and greatly affects the breakout and routing strategy.
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ball-pitch — Alternate spelling of ball pitch.

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base — The electrode of a transistor which controls the movements of electrons or holes by means of an electric field on it. It is the element which corresponds to the control grid of an electron tube.
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beam lead — ()A metal beam (flat metallic lead which extends from the edge of a chip much as wooden beams extend from a roof overhang) deposited directly onto the surface of the die as part of the wafer processing cycle in the fabrication of an integrated circuit. Upon separation of the individual die (normally by chemical etching instead of the conventional scribe-and-break technique), the cantilevered beam is left protruding from the edge of the chip and can be bonded directly to interconnecting pads on the circuit substrate without the need for individual wire interconnections. This method is an example of flip-chip bonding, contrasted with solder bump.   [Graf]
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BGA — See Ball Grid Array.

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bias — (BAHY əs)  Pronunciation Key  noun   [PCB Layout] Routing layer bias. A widely used definition of bias is “A particular tendency or inclination.” (From Random House Dictionary of the English Language, def 2). In PCB layout, bias refers to routing layer bias. On any given layer of a mulitlayer PCB, the bias is the tendency of a route to be parallel to one of the axes (x or y) or oblique (45 degree angle). routing layer bias Lay1-Ysig-RED Lay4-Xsig-BLUE Routing Layer Bias, RED is Lay1-Ysig (biased parallel to the Y axis) and BLUE is Lay4-Xsig (Biased parallel to the X axis)
Obviously, it is the PCB designer (layout person) who controls the routing layer bias within the PCB file. If he is routing manually, he makes sure that the route he is adding trends in the direction of his choosing which is the same direction of the majority of other routes on that layer. With autorouting, the bias for each layer is set by design rule prior to routing.

If manually routing, the PCB designer can easily keep track of routing layer bias by re-naming his layers to include the bias. Altium Designer allows one to do this. Example 4-layer stack-up with renaming of layers:
Lay1 Ysig-&-PWR
Lay2 NegGND
Lay3 NegGND
Lay4 Xsig-&-PWR

If you think of your computer screen as a map, you could consider that the top is north, bottom south and so on. Oblique biases can be simply named by use of NE or SE in the name. “NE” (North East) would be added to layer names where the routes trend from lower left to upper right (or upper right to lower left, no difference here). “SE” (South East) added to a layer name would designate it as having routes that will trend from upper left to lower right. If you used the name “NW,” that would be the same as “SE.” oblique routing is especially suited to mult-row connector with staggered pins Oblique routing is especially suited to manually routing a mult-row connector with staggered pins Routing layer bias is used to prevent wires from shorting as they go from a starting point to an ending point on the PCB. A route is routed in one direction, passed through a via to another layer, and then continued in a different direction. It is this basic technique that permits many criss-crossing connections to be routed in a PCB without shorting.

On layers that have both signals and poured copper, adhering to routing layer bias keeps the poured copper from being isolated. In other words, on such layers, don't route in an anti-bias (wrong way) direction. On a multi-layerd board with many signal and ground plane layers, but with only one signal layer between any two adjacent ground planes, routing layer bias can be safely disregarded in order to reduce via count.

On multi-layer boards with two signal layers between any pair of ground planes, routing layer bias is important to maintain so that signals on adjacent layers cross at right angles to each other, thus avoiding cross-talk. An X-bias would be adjacent to a y-bias layer. A NE-bias layer would be adjacent to a SE-bias layer.
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board
— printed circuit board. Also, a CAD file which represents the layout of a printed circuit.
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board house — Board vendor. A manufacturer of printed circuit boards. Aka fabricator.
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body — The portion of an electronic component exclusive of its pins or leads.
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BOM — [pronounced "bomb"] Bill of Materials. A list of components to be included on an assembly such as a printed circuit board. For a PCB the BOM must include reference designators for the components used and descriptions which uniquely identify each component. A BOM is used for ordering parts and, along with an assembly drawing , directing which parts go where when the board is stuffed.
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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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