Glossary of PCB starts from E-L

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 block.

ECL —Emitter Coupled Logic.  A type of unsaturated 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.

Electrical Object — [Protel] A graphical object (in a PCB or schematic database) to which an electrical connection can be made, such as a component pin or a wire.

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.

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.  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,

Emitter —An electrode on a transistor from which a flow of electrons or holes enters the region between the electrodes. 

EMP —Electromagnetic pulse. A reaction of large magnitude resulting from the detonation of nuclear weapons.

End-to-end design —a version of CADCAMCAE 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. 

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.

     

Fab —Short for fabrication.

Fabrication drawing —A drawing used to aid the construction of a printed board. It shows all of the locations of the holes to be drilled, their sizes and tolerances, dimensions of the board edges, and notes on the materials and methods to be used. Called "fab drawing" for short. It relates the board edge to at least on hole location as a reference point so that the NC Drill file can be properly lined up.

FC —Flexible Circuit, flexible circuitry, flexcircuit or flex circuit.

Fine line design —Printed circuit design permitting two (rarely three) traces between adjacent  DIP pins. It entails the use of a either dry film solder mask or liquid photoimageable solder mask (LPI), both of which are more accurate than wet solder mask.

Fine pitch —Refers to chip packages with lead pitches below 0.050". The largest pitch in this class of parts is 0.8mm, or about 0.031". Lead pitches as small as 0.5mm (0.020") are used.

Finger —A gold-plated terminal of a card-edge connector. [Derived from its shape.]

Flash —1. v. To turn a vector photoplotter lamp on for a brief but precise duration and then off, during which time the relative positions of the lamp and film remain fixed. This exposes the film with the image of a small object (the size and shape of which is controlled by the transparent portion of an aperture).  2. n. A small image on film created in such wise or as directed by a command in a Gerber file .) The maximum size (x or y dimension)for a flash varies from one photoplotting shop to another, but is commonly ½ inch.

Flex circuit —Flexible circuit, or flexcircuit; a printed circuit made of thin, flexible material. For more information, 

Flexible circuitry —An array of conductors bonded to a thin, flexible dielectric. It has the unique property of being a three-dimensional circuit that can be shaped in multiplanar configurations, rigidized in specific areas, and molded to backer boards for specific applications. As an interconnect, the main advantages of flex over traditional cabling are greater reliability, size and weight reduction, elimination of mechanical connectors, elimination of wiring errors, increased impedance control and signal quality, circuit simplification, greater operating temperature range, and higher circuit density. In many applications, lower cost is another advantage of using flexible circuits. 

Flip-chip —A mounting approach in which the chip  is inverted and connected directly to the substrate rather than using the more common wire bonding technique. Examples of this kind of flip-chip mounting are beam lead and solder bump.

First article —A sample part or assembly manufactured prior to the start of production for the purpose of ensuring that the manufacturer is capable of manufacturing a product which will meet the requirements.   

Footprint —1. The pattern and space on a board taken up by a component. 

FPC —Flexible Printed Circuit, 

FR-1 —A low-grade version of FR-2.

FR-2 —A NEMA grade of Flame-Retardant industrial laminate having a substrate of paper and a resin binder of phenolic. It is suitable for printed circuit board laminate and cheaper than the woven glass fabrics such as FR-4.

FR-4 —A NEMA grade of Flame-Retardent industrial laminate having a substrate of woven-glass fabric and resin binder of epoxy. FR-4 is the most common dielectric material used in the construction of PCBs in the USA.  Its dielectric constant is from 4.4 to 5.2 at below-microwave frequencies. As frequency climbs over 1 GHz, the dielectric constant of FR-4gradually drops.

FR-6 — Fire-Retardant glass-and-polyester substrate material for electronic circuits. Inexpensive; popular for automobile electronics. [Stammtisch Beau Fleuve Acronyms .

GC-Prevue —A CAM file viewer and printer made by Graphiicode. The freeware version can store Gerber and NC drill files within a database (.GWK extension), which makes it extremely useful for sharing electronic data:   Because it is free, anyone can download and use it for importing Gerber files in a logical sequence, displaying them in perfect register, annotating (adding labels to the filenames to describe their use and position in the stackup) and viewing them, saving all that and then passing the resulting .GWK file on to another for examination. Besides merely looking at the files or printing them, GC-Prevue has features for measuring objects' size and relative distance from each other. To my (John Childers') knowledge, GC-Prevue is the only free Gerber viewer that sets-up and saves Gerber data in a database file. Other free Gerber viewers require one to set up the Gerber files each time and won't allow saving the set-ups unless one buys an upgrade. (From the viewpoint of a printed circuit designer serving engineers or customers, this inability to save set-ups makes the competing free Gerber viewers completely useless for sharing Gerber data.)

Gerber file —ASCII data file used to control a photoplotter. Named after H. Joseph Gerber, founder of Gerber Scientific Co., who invented the original vector photoplotter.

Hard copy —A printed or plotted form of an electronic document (computer data file).

Header —The portion of a connector assembly which is mounted on a printed circuit.

Hole —In a semiconductor, the term used to describe the absence of an electron; has the same electrical properties as an electron except that it carries a positive charge.  

HPGL —Hewlett-Packard Graphics Language, a text-based data structure of pen-plot files which are used to drive Hewlett-Packard pen plotters. Although Hewlett-Packard no longer makes pen plotters, the large-format dot matrix printers which replaced them can also be driven by HPGL.

Hybrid —Hybrid circuit. Any circuit made by using a combination of the following component manufacturing technologies:monolithic IC,thin film, thick film and discrete component.

Integrated circuit —1)miniaturized electronic circuit that has been manufactured as a chip(die). 2)A packaged chip

IPC —The Institute for Interconnecting and Packaging Electronic Circuits, the final American authority on how to design and manufacture printed wiring.   In 1999, IPC changed its name from Institute of Interconnecting and Packaging Electronic Circuits to IPC. The new name is accompanied with an identity statement, Association Connecting Electronics Industries. 

Laser photoplotter —(also "laser plotter") A photoplotter which simulates a vector photoplotter by using software to create a raster image of the individual objects in a CAD database, then plotting the image as a series of lines of dots at very fine resolution. A laser photoplotter is capable of more accurate and consistent plots than a vector photoplotter.

LGA —1.  Land Grid Array.  

Lead (pronounced "leed") —A terminal on a component.

Liquid photoimageable solder mask (LPI) —A mask sprayed on using photographic imaging techniques to control deposition. It is the most accurate method of mask application and results in a thinner mask than dry film solder mask. It is often preferred for dense SMT.

LPI — stands for Liquid PhotoImageable. Refers to liquid photoimageable solder mask.

In this article I have tried to include the words which generally used in PCB designing and manufcturing.