GLOSSARY of Printed Circuits

Index to terms on this page:

fab   fabricate  
fabrication drawing   fabricator   FAR   FBGA   FC   FCB   FCPB   FDIR   female   ferrite   ferrite bead   FG   FF   FFC  
fine line design  
fine pitch   finger   Finite element analysis   Finite element method   FIT  
first article   flash   flat file database  
flex circuit or  flexcircuit  
flexible circuitry  
flexible printed circuit   flip-chip or  flip chip   fly-by topology   FMC   foil   footprint  
footprint naming convention   form factor   FPC   FPCB   FPGA   FPY   FQFP   FQFP-N   FR-1   FR-2   FR-4   FR-6   FSFS  

fab — Short for fabrication or fabricate.

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fabricate — verb  [PCB Manufacturing] (Of a bare board) Manufacture.

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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.

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fabricator — PCB bare board manufacturer.

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FAR — Federal Acquisition Regulation

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FBGA — (EF-BEE-GEE-AY)   Pronunciation Key  noun  [Components] Fine-pitch Ball Grid Array or designated by Altera as Fine-line Ball Grid Array. In practice this refers to ball grid arrays with ball pitches of 1mm or less, but larger than 0.5mm.
A BGA with 0.5mm or less ball pitch is called MBGA (Micro Ball Grid Array). An intermediate ball pitch of 0.8mm is called by many an FBGA, while Altera refers to this as UBGA, meaning Ultra FBGA.

   IPC-7351B footprint naming convention: BGA+Pin Qty+C+Col Pitch X Row Pitch P + Ball Columns X Ball Rows_Body Length X Body Width X Height-N

BGA Note: In the section of the name Pin Qty+C, C C = Collapsing balls. The only alternative for this use of C would be N, which = Non-collapsing balls.
An N at the end of the name = Nominal Material Condition (Could also be M for Most or L for Least)

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

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FCB — Flexible Circuit Board. See flexible printed circuit.

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FCPB — Flexible Circuit Printed Board (Flexible Printed Circuit Board). See flexible printed circuit.

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FDIR — Final Draft for Industry Review

< You will often hear this stage referred to by its acronym FDIR. During this stage, the draft document is made available for 30-day review for comments to the working group, Committee Chair Council (CCC) and other IPC groups with interest. IPC also makes the document available to the general public. During this stage, IPC forms the consensus ballot group for the standard.

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female — Politically incorrect modifier which denotes a socket-type connector terminal.

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ferrite — Also called ferrospinel. A powedered, compressed and sintered magnetic material having high resistivitry. [Graf, Rudolf F. Modern Dictionary of Electronics. Newnes, 1999]

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ferrite bead —

1. A magnetic device made of ferrite powder mixtures in the form of a bead fired on the current-carrying wires of a circuit component. [Graf, Rudolf F. Modern Dictionary of Electronics. Newnes, 1999]
   This can be used in many ways. Going back to early non-silicon-chip-based main-frame computers, it was used in a memory matrix as a magnetic device for storage of information. Today it is often used similar to the choke type of inductor. An accelerated current (a rising or falling signal pulse, a sudden change in current or simply an alternating current) induces a magnetic field when it passes it through the coil of an inductor (choke) and so impedes the current, which is called reactance. A ferrite bead imparts reactance to an accelerated current as well, except the magnetic field is present permanently in the ferrite, not induced through a coil. The magnetic energy is contained in the magnetic material of the ferrite bead.
2. The microwave engineer uses a ferrite bead to pass direct current (dc) to a circuit while at the same time the ferrite bead provides a measure of isolation between the bias supply and the circuit. The loss (high frequency resistance or reactance) imparted by the ferrite bead minimizes the risk of parasitic resonances between several reactive components that exist in the circuit to be biased and the bias supply. Other applications include providing a high permeability low loss core for transformer or inductor applications. [Weber]
3. Sometimes known as "prayer beads," in that a EE might sprinkle them liberally on a PCB hoping that this will cause the board to pass EMC testing. [Taranovich]

Cited Works:

Weber, Robert J. "Ferrite Bead Laboratory." ECpE Department Laboratory Manuals. IOWA STATE UNIVERSITY, 18 Aug. 2006. Web. 10 Nov. 2011.
Weir, Steve. "PDN Application of Ferrite Beads." DesignCon 2011: Santa Clara, California, USA, 31 January-3 February 2011, Curran Associates Inc, 2011, pp. 801-822.
Taranovich, Steve, and Paul Rako. "12-Bit ADCs in the 32-Bit Atmel SAM D20." EDN, EDN, 2 July 2013, https://www.edn.com/12-bit-adcs-in-the-32-bit-atmel-sam-d20/.

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FG — (device prefix)

1. A TI package prefix referring to PLCC packages.
2. A Xilinx packagae prefix referring to FinePitch (1 mm) BGA packages, namely FG256, FG456, FG676, and FG680.

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FF — (device prefix) A Xilinx package prefix referring to Flip-chip Fine-pitch (1 mm) BGA packages, namely FF896, FF1152 and FF1517.

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FFC — Flexible Flat Cable or Flat Flex Cable, either way it means the same thing. Compare with FPC. Connectors designed for FFCs most likely will also accomodate FPCs.

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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.

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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.

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

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Finite element analysis — From Wikipedia, the free encyclopedia. https://www.wikipedia.org/wiki/Finite_element_method
Finite element analysis (FEA) is the application of the finite element method to the analysis of static or dynamic physical objects and systems. In it, the object or system is represented by a geometrically similar model consisting of multiple, linked, simplified representations of discrete regions, aka finite elements. Equations of equilibrium, derived from applicable physical considerations, are applied to each element, and a system of simultaneous equations is constructed. The system of equations is solved for unknown values using the techniques of linear algebra. The accuracy of the solution may be indefinitely improved through the increase in number, and corresponding decrease in size, of the elements.
FEA is used to analyze objects and systems that are of sufficient complexity that analysis with simpler closed-form analytical methods will not yield results of adequate accuracy, and permits the solution of problems which could not otherwise be solved. In practice, it is accomplished through the use of digital computers due to the very large number and size of the simultaneous equations required for most analyses.
A common use of FEA is for the determination of stresses and displacements in mechanical objects and systems. However, it is also routinely used in the analysis of many other types of problems, including those in heat transfer and fluid mechanics.
FEA is used to calulate and control differential impedance and other electrical characteristics in PCBs. This flavor of FEA uses "Green fields" as the basis of a calculator known as a "2D Field Solver." An advancement of this is a "3D Field Solver" for extending the calculations to vias.

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Finite element method — From Wikipedia. https://www.wikipedia.org/wiki/Finite_element_method

The finite element method is used for solving partial differential equations (PDE). Solutions are achieved by either eliminating the differential equation completely (steady state problems), or rendering the PDE into an equivalent ordinary differential equation, which is then solved using standard techniques such as finite differences, etc. Use of the finite element method in engineering for the analysis of physical systems is commonly known as finite element analysis.

Finite element methods have also been developed to solve integral equations such as the heat transport equation.

The method was introduced by Richard Courant to solve torsion on a cylinder. Courant's contribution was evolutionary, drawing on a large body of earlier results for PDEs developed by Rayleigh, Ritz and Galerkin. Development of the method began in earnest in the middle to late 1950s for airframe and structural analysis, and picked up a lot of steam at Berkeley in the 1960s for use in civil engineering. The method was provided with a rigorous mathematical foundation in 1973 with the publication of Strang and Fix's The Finite Element Method.

In solving partial differential equations, the primary challenge is to create an equation which approximates the equation to be studied, but which is stable, meaning that errors in the calculation do not acculumlate and cause the resulting output to be garbage.

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FIT — Flexible and Interoperable Data Transfer Protocol.

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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.   [Graf, Rudolf F. Modern Dictionary of Electronics. Newnes, 1999]

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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.

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flat file database — - A flat file database describes any of various means to encode a database model (most commonly a table) as a single file (such as .txt or .ini). A "flat file" is a plain text or mixed text and binary file which usually contains one record per line or 'physical' record (example on disc or tape). There are no structural relationships between the records. [Wikipedia]

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flex circuit or flexcircuit — Flexible circuit. A printed circuit made of thin, flexible material. For more information, see flexible circuitry.

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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.

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flexible printed circuit — Flex circuit. Abbreviated FPC or FC.

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flip-chip or flip chip — A mounting approach in which the chip ( die ) 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. High temperature solder balls are attached directly to the silicon die. (See also BT.)

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fly-by topology — For better signal quality at higher speed grades, DDR3 adopts a so called fly-by architecture for the commands, addresses and clock signals. This effectively reduced the number of stubs and signaling length from the DDR2 T-Branch architecture to a more elegant and straightforward design.


The Fly-by topology generally connects the DRAM chips on the memory module in a series, and at the end of the linear connection is a grounded termination point that absorbs residual signals, to prevent them from being reflected back along the bus.
https://www.bit-tech.net/hardware/memory/2008/02/10/the_secrets_of_pc_memory_part_4/3
Laying out routes on a PCB to implement fly-by topology is a challenge. Altium Designer's xSignals feature added in 2015 provides an added tool for addressing this topology as well as other high speed topologies.

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FMC — VITA 57 FPGA Mezzanine Card, a standard ratified in 2008 by the American National Standards Institute (ANSI). The FMC standard was created to provide a standard mezzanine card form factor, connectors, and modular interface to an FPGA located on a base board (carrier card).
Decoupling the I/O interfaces from the FPGA in this manner simplifies I/O interface module design while maximizing carrier card reuse. Unlike the PMC and XMC standards that use complex interfaces like PCI, PCI-X, PCIe®, or Serial RapidIO to interface to the carrier card, the FMC standard requires only the core I/O transceiver circuitry that connects directly to the FPGA on the carrier card.
I/O Design Flexibility with the FPGA Mezzanine Card (FMC) By Raj Seelam.

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foil — A sheet of copper of various thicknesses used most commonly as an outer layer in the construction of a PCB stack-up (q.v.).

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footprint — (FUUT-print)   Pronunciation Key 

1. noun  [PCB Manufacturing] The pattern and space on a printed board taken up by a component.
2. noun  [PCB Layout] A graphic software (artwork) representation of the pattern and space on a printed circuit board taken up by a component, with special handling for the portions for solder to attach. On a manufactured board the body of a footprint is represented as an epoxy-ink outline and the terminals as exposed metal.
   
   In Altium Designer, a footprint can have a 3D body.
   
   Footprints are designed by the PCB designer based on mechanical drawings from manufacturers. Also called a land pattern, the footprint forms the pattern of exposed metal on a PCB that allows the component to be soldered. If the component is a through-hole type, the footprint includes numerical controlled drill data, so that the holes that the leads get inserted into are available and in a pattern that fits the component. Footprints in artwork become patterns on manufactured PCBs and should be carefully vetted so that errors don't occur during assembly.
   
   A footprint is given a name by the PCB designer when he builds it. The name of a footprint is customarily a description of its size and shape and can also include an abbreviation standing for the category of electrical function of its corresponding component. E.g. CAP, RES, DIO or LED for capacitor, resistor, diode or light emitting diode respectively.
   
   Also called a decal, because hand tape-up of printed circuit boards employed the use of pull-off and paste decals to represent components.
   
   Also called a part or package.
   
   [The derivation of the term is intuitive and metaphorical. In forensics, a footprint made by a person can be matched to his shoe and place him at the scene of a crime. In PCB manufacturing, the footprint had better match the component or someone is in trouble.]

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footprint naming convention — Land pattern naming convention, q. v.
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form factor —  [PCB Design]  The overall size and shape of the PCB with mounting hardware and input/output connector locations specified.
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FPCB — Flexible Printed Circuit Board

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FPGA — Field Progammable Gate Array

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FPY — first pass yield

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FQFP — Fine-pitch Quad Flat Pack

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FQFP-N — Fine-pitch Quad Flat Pack No-lead. The acronym is commonly shortened to QFN (Quad Flat No-Lead). A type of LCC. Also known as MLP or MLF packages.

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FR-1 — Flame Retardant-1, a NEMA grade of industrial laminate. A low-grade version of FR-2.

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FR-2 — Flame Retardant-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.

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FR-4 — Flame Retardant-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-4 gradually drops.

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FR-6 — Flame Retardant-6, a Fire-Retardant glass-and-polyester substrate material for electronic circuits. Inexpensive; popular for automobile electronics. [Stammtisch Beau Fleuve Acronyms http://www.plexoft.com/SBF/F05.html#FR-4]

An article written in 2017 by Atar Mittal of Sierra Circuits is worth study if you need to choose PCB materials for your electronics project. It includes a "Laminate Selector Chart" entitled "PCB Material Properties and Recommended Application Areas" HDI PCBs: Choosing The Right Material

A comparison of many brands of PCB laminates can be found in the Standard Printed Circuits   "Microwave Laminates Comparison Chart."

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FSFS — Fast Secure File System. A flat-file system used for repository storage in Subversion. It is in the form of a filesystem tree--hierarchy of files and directories. [See Wikipedia Apache_Subversion Filesystem]

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