A
active component
1. A component which adds energy to the signal it passes. 2. A device
that requires an external source of power to operate upon its input
signal(s). 3. Any device that switches or amplifies by the application
of low-level signals. Examples of active devices which fit one or more
of the above definitions: transistors, rectifiers, diodes, amplifiers,
oscillators, mechanical relays and almost all IC's (Contrast with
passive component)
AlN
Aluminum Nitride, a compound of aluminum with nitrogen
AlN Substrate
A substrate of aluminum nitride.
alumina
A ceramic used for insulators in electron tubes or substrates in
thin-film circuits. It can withstand continuously high temperatures
and has a low dielectric loss over a wide frequency range. Aluminum
oxide (Al2O3)
analog circuit
A circuit in which the output varies as a continuous function of the
input, as contrasted with digital circuit .
anode
1. The positive element such as the plate of a vacuum tube; the
element to which the principal stream of electrons flows. 2. In a
cathode-ray tube, the electrodes connected to a source of positive
potential. These anodes are used to concentrate and accelerate the
electron beam for focusing.
ANSI
American National Standards Institute. Founded in 1918 by five
engineering societies and three government agencies, the Institute
remains a private, nonprofit membership organization supported by a
diverse constituency of private and public sector organizations.
artwork
Artwork for printed circuit design is photoplotted film (or merely the
Gerber files used to drive the photoplotter), NC Drill file and
documentation which are all used by a board house to manufacture a
bare printed circuit board.
assembly
1. The process of positioning and soldering components to a PCB. 2.
Act or process of fitting together parts to make a whole. 3. A number
of parts of subassemblies or any combination therefore joined
together.
ASSEMBLY, DOUBLE-SIDED
A packaging and interconnecting structure with components mounted on
both the primary and secondary sides.
assembly drawing
A drawing depicting the locations of components, with their reference
designators , on a printed circuit. Also called "component
locator drawing."
assembly house
A manufacturing facility for attaching and soldering components to a
printed circuit.
ASSEMBLY, MULTILAYER PRINTED CIRCUIT
A multilayer printed circuit board on which separately manufactured
components and parts have been added.
ASSEMBLY, MULTILAYER PRINTED WIRING
A multilayer printed wiring board on which separately manufactured
components and parts have been added.
ASSEMBLY, PACKAGING AND INTERCONNECTING (P&IA)
The generic term for an assembly that has electronic components
mounted on either one or both sides of a packaging and interconnecting
structure.
ASSEMBLY, PRINTED BOARD
An assembly of several printed circuit assemblies or printed wiring
assemblies, or both.
ASSEMBLY, PRINTED CIRCUIT
A printed circuit board on which separately manufactured components
and parts have been added.
ASSEMBLY, PRINTED WIRING
A printed wiring board on which separately manufactured components and
parts have been added.
ASSEMBLY, SINGLE-SIDED
A packaging and interconnecting structure with components mounted only
on the primary side.
ASTM
American Society of Testing and Materials. http://www.astm.org/index.shtml
ATE
Automatic Test Equipment. (See also DUT.) .
AWG
American Wire Gauge. A PCB Designer needs to know diameters of wire
gauges to properly size E-pads . The American Wire Gauge, formerly
known as the Brown and Sharpe (B + S) Gauge, originated in the wire
drawing industry. The gauge is calculated so that the next largest
diameter always has a cross-sectional area that is 26% greater. From
this basic relationship, the following rules can be deduced: ( click
here for an explanation of the ASTM data by Global Wire Group.)
auto-router
automatic router, a computer program that routes a PC board design (or
a silicon chip design) automatically.
B
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
can tax the limits of the PCB manfacturer, usually requiring 4 mil
tracks and 4 mil spaces (less for micro BGA ) and (2) 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.
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.
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]
BASE MATERIAL
The insulating material upon which the conductor pattern may be
formed. The base material may be rigid of flexible. It may be a
dielectric sheet or insulated metal sheet.
BASIC DIMENSION
Theoretically exact location of a component feature, indicated by a
symbol or a number in a box.
(The tolerance on a base dimension location)
BGA
Ball Grid Array .
board
printed circuit board. Also, a CAD database which represents the
layout of a printed circuit.
board house
Board vendor. A manufacturer of printed circuit boards.
body
The portion of an electronic component exclusive of its pins or leads.
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.
BUMPERED QUAD FLAT PACK (BQFP)
Package with leads extending from four sides, in a gull wing lead
form, that has plastic corners that stick out from the package.
BTD
Broken Tool Detector (Infrared Optics)
C
C4
Controlled Collapse Chip Connect. A type of flip-chip technology which
is used in Intel's Pentium III.
CAD
Computer Aided Design. A system where engineers create a design and
see the proposed product in front of them on a graphics screen or in
the form of a computer printout or plot. In electronics, the result
would be a printed circuit layout.
CADCAM
Simply a concatenation of the two terms CAD and CAM.
CAE
Computer Assisted Engineering. In electronics work, CAE refers to
schematic software packages.
CAF
Conductive Anodic Filamentation (or Conductive Anodic Filament growth)
- An electrical short which occurs in PCBs when a conductive filament
forms in the laminate dielectric material between two adjacent
conductors under an electrical bias. CAF is a potentially dangerous
source of electrical failure in the PCB. As PCB designs have increased
in density, with hole-to-hole spacings reduced to 25 mils or less, CAF
has become an everyday concern. [adapted from Erik J. Bergum, "CAF
Resistance of NON- DICY FR-4," PC FAB, 9/2002]
CAM
Computer Aided Manufacturing. (See CAM files )
CAM files
CAM means Computer Aided Manufacturing. These are the data files used
directly in the manufacture of printed wiring. . The types of CAM
files are 1) Gerber file, which controls a photoplotter, 2) NC Drill
file, which controls an NC Drill machine and 3) fab and assembly
drawings in soft form (pen-plotter files). CAM files represent the
valuable final product of PCB design. They are handed off to the board
house which further refines and manipulates CAM data in their
processes, for example in step- and-repeat panelization. Some PCB
design software companies refer to all plotter or printer files as CAM
files , although some of the plots may be check plots which are not
used in manufacture.
capture
1. To draw (schematics) with CAE software in such a way that data,
especially connectivity, can be extracted electronically. The
extracted data would minimally be a netlist and preferably also a BOM
. The more useful data that is included (captured) in the schematic,
the more useful will be the BOM and netlist extracted from it. 2.
Extract information automatically through the use of software, as
opposed to hand-entering of data into a computer file.
card
another name for a printed circuit board.
card-edge connector
A connector which is fabricated as an integral portion of a printed
circuit board along part of its edge. Often employed to enable a
daughter or add-on card to be plugged directly into another much
larger printed board, the motherboard or backplane.
CASTELLATION
metalized features that are recessed on the edges of a chip carrier
which are used to interconnect conducting surfaces or planes within or
on the hip carrier.
cathode
1. In an electron tube the electrode through which a primary source of
electrons enters the interelectrode space. 2. General name for any
negative electrode. 3. When a semiconductor diode is biased in the
forward direction, that terminal of the diode which is negative with
respect to the other terminal. 4. In electrolytic plating, the
workpiece being plated. [Graf]
CERAMIC
Inorganic, nonmetallic material, such as alumina or beryllia.
CERAMIC LEADLESS CHIP CARRIER
Ceramic package having metalized contacts at it's periphery instead of
wire leads.
CERAMIC QUAD FLAT PACK
Ceramic package with leads extending from four sides in a gull wing
form.
CERDIP
Dual In-line Package consisting of a leadframe encased with a ceramic
shell.
check plots
Pen plots that are suitable for checking only. Pads are represented as
circles and thick traces as rectangular outlines instead of filled-in
artwork. This technique is used to enhance transparency of multiple
layers.
chip
1. An integrated circuit manufactured on a semiconductor substrate and
then cut or etched away from the silicon wafer . (Also called a die .)
A chip is not ready for use until packaged and provided with external
connections. 2. Commonly used to mean a packaged semiconductor device.
CHIP CARRIER (CC)
A low-profile package whose chip cavity or mounting area occupies a
major fraction of the package area and whose terminals consist of
metal pad surfaces (on the leadless versions) or leads formed around
the sides and under the package or out from the package (on leaded
versions).
NOTES: 1. The body of the chip carrier, usually square or of low
aspect ratio, is similar to that of a flatpack. 2. When leads extend
out from the package, the preferred term is "flatpack".
chip-on-board
Abbreviated COB. In this technology integrated circuits are glued and
wire-bonded directly to printed circuit boards instead of first being
packaged. The electronics for many mass-produced toys are embedded by
this system, which can be identified by the black glob of plastic
sitting on the board. Underneath that glob (technical term: glob top
), is a chip with fine wires bonded to both it and the landing pads on
the board.
chip scale package
A chip package in which the total package size is no more than 20%
greater than the size of the die within. Eg: Micro BGA.
CID
Certified Interconnect Designer
CIM
Computer Integrated Manufacturing. Used by an assembly house, this
software inputs assembly data from a PCB CAM/CAD package, such as
Gerber and BOM, as input and, using a pre-defined factory modeling
system, outputs routing of components to machine programming points
and assembly and inspection documentation. In higher end systems, CIM
can integrate multiple factories with customers and suppliers.
[SMT magazine, http://www.smtmag.com/ ]
clad
A copper object on a printed circuit board. Specifying certain text
items for a board to be "in clad" means that the text should
be made of copper, not silkscreen .
CLAMPED PACKAGE (PRESS-PACK) (CP)
A package, for high-current devices, in the form of a cylinder with a
plane, circular high-current terminal on each end, intended to be
clamped against or between two bus bars acting as heat sinks.
COEFFICIENT OF THERMAL EXPANSION (CTE)
The linear thermal expansion per unit change in temperature.
collector
1. An electrode in a transistor that collects electrons or holes. 2.
In certain electron tubes, an electrode to which electrons or ions
flow after they have completed their function.
component
Any of the basic parts used in building electronic equipment, such as
a resistor, capacitor, DIP or connector, etc.
component library
A representation of components as decals, stored in a computer data
file which can be accessed by a PCB CAD program.
COMPONENT MOUNTING SITE
A location o a P&I structure that consists of a land pattern and
conductor fan-out to additional lands for testing or vias that are
associated with mounting of a single component
CONDUCTIVE PATTERN
The configuration or design of the conductive material on the base
material. (includes conductors, lands, and through connections when
these connections are in integral part of the manufacturing process).
CONDUCTOR
A single conductive path in a conductive pattern.
connection
One leg of a net . Also called a "pin pair."
connectivity
The intelligence inherent in PCB CAD software which maintains the
correct connections between pins of components as defined by the
schematic.
connector
A plug or receptacle which can be easily joined to or separated from
its mate. Multiple-contact connectors join two or more conductors with
others in one mechanical assembly.
CONSTRAINING CORE
A supporting plane that is internal to a packaging and interconnecting
structure.
COPLANARITY
Distance from the seating plane to the lead farthest from the seating
plane.
COURTYARDS
The area required to place land patterns and their respective
components in adjacent proximity without interference or shorting.
CSP
Chip Scale Package
CYLINDER OR CAN (CY)
A generally cylindrical package. It usually has terminals that exit
from one end parallel to the central axis of the package and mounts
perpendicular to the seating plane
D
database
A collection of interrelated data items stored together without
unnecessary redundancy, to serve one or more applications.
decal
A graphic software representation of a component, so named because
hand tape-up of printed circuit boards employed the use of pull-off
and paste decals to represent components. Also called a part,
footprint or package . On a manufactured board the body of a footprint
is an epoxy-ink outline.
device
Any type of electrical component on a PC board. It will have functions
and properties unique to its type. In a schematic (and the extracted
BOM ) , it will be labeled with a value or device number. There are
two main classes of devices, passive and active. .
DICY
Dicyandiamide, the most common cross-linking agent used in FR-4 .
[Erik J. Bergum, "CAF Resistance of NON- DICY FR-4," PC FAB,
9/2002]
die
1. A chip . (Plural: dice)
dielectric constant
The ratio of the capacitance of a capacitor with the given dielectric
to the capacitance of a capacitor having air for its dielectric but
otherwise identical. [Graf]
digital circuit
A circuit which operates like a switch (it is either "on" or
"off"), and can make logical decisions. It is used in
computers or similar decision making equipment.
diode
1. A device, as a two-element electron tube or a semiconductor,
through which current can pass freely in only one direction. [Random
House] 2. A semiconductor device with two terminals and a single
junction, exhibiting varying conduction properties depending on the
polarity of the applied voltage. [Graf]
DIP
Abbreviation for Dual In-line Package. A type of housing for
integrated circuits. The standard form is a molded plastic container
of varying lengths and 0.3 inch wide (although there are other
standard widths), with two rows of through-hole pins spaced 0.1 inch
between centers of adjacent pins.
DISK-BUTTOM (DB)
A low-profile package that looks like a disk or button. It usually has
terminals that exit radially from the periphery of the package like
spokes of a wheel or from the disk center. Terminals may be formed
into a variety of shapes.
DIP
Dual In-line Package designed with leads for through-hole mounting.
Lead pitch is 2.54mm (.100")
DOS
Disk Operating System. A program that controls the computer's transfer
of data to and from a hard or floppy disk. Personal computers that are
IBM-compatible run DOS rather than other early varieties of operating
systems.
DOS-formatted
(Of magnetic data storage media, such as floppy disks.) Prepared for
storage of data in such a way that DOS transfer can occur.
double-track
Slang for fine line design with two traces between DIP pins.
DPAK
Motorola surface mount replacement for the TO-220 transistor package.
dry film solder mask
A solder mask film applied to a printed board with photographic
methods. This method can manage the higher resolution required for
fine line design and surface mount. It is more expensive than liquid
photoimageable solder mask.
DUAL IN-LINE PACKAGE (DIP)
A component which terminates in two straight and parallel rows of pins
or lead wires.
DUT
Device Under Test. A DUT board (probe card) is used in automated
testing of integrated circuits. It is part of the interface between
the chip and a test head, which in turn attaches to computerized test
equipment. The specific test equipment used will determine the value
of the controlled impedance required for the chip tester boards.
Depending on which system it is designed for, one type of DUT board is
used in testing individual integrated circuits in a silicon wafer
before they are cut free and packaged, and another type is used for
testing packaged IC 's.
E
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 blocks .
ECL
Emitter Coupled Logic. A type of unsaturated logic 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.
[Graf]
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. [From the National Instruments, Developer Zone, Measurement
Encyclopedia] 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, Zuken.
emitter
An electrode on a transistor from which a flow of electrons or holes
enters the region between the electrodes. [Random House]
EMP
Electromagnetic pulse. A reaction of large magnitude resulting from
the detonation of nuclear weapons.
end-to-end design
a version of CADCAM CAE 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. For an introduction
to the overall design flow of an electronics project, see the PCB
designer definition and follow the link to the plain English
description for a printed circuit board designer
ESD
Electrostatic discharge, when a static charge moves from one surface
to another.
F
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.
FIBER OPTIC (FO)
A microcircuit package that has one or more fiber-optic connectors.
Its terminals may exit from, or attach to, any surface of the package
and may be formed in a variety of lead shapes. NOTE: The fiber-optic
connectors are considered to be terminals.
FIDUCIAL
.040" round etch pad with a .080" min. solder mask
clearance. Used as a bomb-site target for automated assembly equipment
alignment tools.
FIDUCIAL, GLOBAL
Are placed in three corners, generally next to the tooling holes, of a
printed circuit board. They are used for assembly equipment alignment
tools.
FIDUCIAL, LOCAL
Are placed in 2 corners of fine pitch quad flat packages. They are
used for assembly equipment alignment.
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.
FINE-PITCH TECHNOLOGY (FPT)
Surface mounted components with a lead or termination pitch of 0.63 mm
or less.
finger
A gold-plated terminal of a card-edge connector. [Derived from its
shape.]
FLANGE MOUNT (FM)
A package that has a flange-mounted heat sink that is an integral part
of the package and provides mechanical mounting to a packaging
interconnect structure or cold plate. It usually has terminals that
exit from, or attach to, any surface of the package in a variety of
forms.
FLAT PACK (FP)
Package with leads on 2 sides. A low-profile package whose leads
project parallel to, and are designed primarily to be attached
parallel to, the seating plane. (Normally) Leads may be formed
generally away from the package body. If the leads are formed back
towards the package body, the correct term is "Chip
Carrier". NOTES: 1. The leads typically originate at either two
or four sides of a package. 2. The body of the flatpack is similar to
that of a chip carrier.
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 .
footprint
1. The pattern and space on a board taken up by a component. 2. Decal
.
FR-2
Flame-Retardant paper substrate material for cheap electronic
circuits. [Stammtisch Beau Fleuve Acronyms http://www.plexoft.com/SBF/F05.html#FR-4]
FR-4
Fire-Retardent glass/epoxy laminate, the most common dielectric
material used in the construction of PCBs. 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.
FR-6
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]
G
GAGE PLANE
A plane established above the seating plane to be used as a standard
for measuring lead length.
gerber or Gerber
see Gerber file.
Gerber file
Data file used to control a photoplotter . Named after Gerber
Scientific Co., who made the original vector photoplotter .
glob top
A blob of non-conductive plastic, often black in color, which protects
the chip and wire bonds on a packaged IC and also on a chip on board .
This specialized plastic has a low coefficient of thermal expansion so
that ambient temperature changes will not rip loose the wire bonds it
is designed to protect. In high-volume chip on board production, these
are deposited by automated machinery and are round. In prototype work,
they are deposited by hand and can be custom-shaped; however, in
designing for manufacturability, one assumes a prototype product will
"take- off" and ultimately have high market demand, and so
lays out chip on board to accommodate a round glob top with adequate
tolerance for machine-driven "slop-over".
GRID ARRAY (GA)
A low-profile package whose terminals are located on one surface in a
matrix of at least three rows and three columns; terminals may be
missing from some row-column intersections.
GULL WING
Leads that formed with a bend that looks like a birds wing
H
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.
HEAT SINK
Heat conductive material used to transmit heat from the silicon chip
to the external environment. Usually a heat sink is made of metal,
typically aluminum.
HEAT SLUG
Heat sink that is exposed to the external environment.
HEAT SPREADER
Heat sink that is internal to the package.
HEAT DISSIPATING QFP (HQFP)
Quad flat pack designed with a heat sink.
HEAT DISSIPATING SOP (HSOP)
Small-outline package designed with a heat sink.
HEAT DISSIPATING SSOP (HSSOP)
Shrink small-outline package designed with a heat sink.
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. [Graf]
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.
I
INTEGRATED CIRCUIT (IC)
An assembly of miniature electronic components simultaneously produced
in batch processing, on or within a single substrate to perform an
electronic circuit function.
IEEE
Institute of Electrical and Electronic Engineers. IEEE Standards
Board, 445 Hoes Lane, Piscataway, New Jersey 08855-1331 USA.
800-678-4333, www.ieee.org
IN-LINE PACKAGE (IP or IL)
A rectangular package having one row or two or more parallel rows of
leads designed primarily for insertion mounting perpendicular to the
seating plane.
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.
J
JEDEC
Joint Electronic Device Engineering Council.
J-LEAD
Leads formed into a J pattern.
JUMPER WIRE
An electrical connection that is a part of the original design, added
between two points on a printed wiring board after the intended
conductive pattern is formed.
K
L
LAND
A portion of a conductive pattern usually, but not exclusively, used
for the connection, or attachment, or both of components.
LAND PATTERN
A combination of lands intended for the mounting, interconnection and
testing of a particular component.
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.
LCATS
Large Capacity Automatic Tool System (Original Version of TMS)
LEAD
External Solderable metal leg strip coming from the component.
LEAD FRAME
The metallic portion of the package that completes the electrical path
from the internal package to the external.
LEADLESS CHIP CARRIER (LCC)
Package with metalized contacts at it's periphery instead of wires.
LFBGA
Low-profile, fine-pitch ball grid array (.80mm pitch). Provide a
minimal footprint and can benefit high bit-width applications. LFBGA's
offer more power and ground pins than other packages, providing a
clear advantage in ground bounce. This package provides the most
effective solution for performance issues such as high thermal power
dissipation, skew and pin-to-pin inductance. Small impedance variation
between pins on the LFBGA package results in lower Skew.
LGA
1. Land Grid Array. The following is a good explanation of Land Grid
Arrays, complete with illustrations: http://www.oki.com/semi/english/packfbga.htm
2. Leadless Grid Array. An example package drawing, not necessarily
representative of this type, can be found on page 9 of http://www.hynix.co.kr/kor/products/system_ic/sp/down/HM6C5332.pdf
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.
LONG-FORM PACKAGE (LF)
A cylindrical or elliptical tubular package having terminal end-caps
or axial leads.
LPI
stands for Liquid PhotoImageable. Refers to liquid photoimageable
solder mask.
LTC
Laser Tool Check (Visable Red Optics)
M
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.
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.
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.
MASTER DRAWING
A document that shows the dimensional limits or grid locations
applicable to any or all parts of a printed board (rigid of flexible),
including the arrangement of conductive and nonconductive patterns or
elements.
MCH
Multiple Cassette Holder (5 Cassettes, CNC-7 Only)
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.
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.
micro ball grid array
A fine pitch ball grid array. Fine pitch for BGAs is anything less
than 1.27 mm [50 mil ] (some say 1.00 mm [39 mil]). SMTnet terms and
definitions SMT in Line terms and definitions.
micro BGA
micro Ball Grid Array.
MICROELECTRONIC ASSEMBLY (MA)
An assembly of unpackaged microcircuits and/or packaged microcircuits,
which may also include discrete devices, so constructed on a packaging
interconnect structure that for the purpose of specification, testing,
commerce, and maintenance, the package is considered to be an
indivisible component.
MICROWAVE PACKAGE (MW)
A package specially designed to provide device operation at microwave
frequencies
mil
One thousandth of an inch (0.0254 mm).
MIXED MOUNTING TECHNOLOGY
A component mounting technology that uses both through-hole and
surface mounting technologies on the same
packaging and interconnecting structure
MLC
Multi-Layer Ceramic
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.
MOLD FLASH
Thin layer of mold compound that extends from the sides of the package
onto the leads and/or between the leads generated during
encapsulation.
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]
MPF
Multiple Pressure Foot (Insert), (Insert Changer, CNC-7 Only)
MQUAD
Quad flat pack style package with a metal shell as opposed to plastic.
MQUAD is a trademark of Olin Corporation, registered in the USA
MRP
Manufacturing resource planning
MTF
Multi-layer Thin Film.
mullite
A substrate compound of alumina and silica (3Al2O3•2SiO2).
MULTICHIP MODULE (MCM)
A module or package capable of supporting several chips on a package.
multimeter
A portable test instrument which can be used to measure voltage,
current, and resistance.
N
NC drill
Numeric Control drill machine. A machine used to drill the holes in a
printed board at exact locations, which are specified in a data file.
NC drill file
A text file which tells an NC drill where to drill its holes.
negative
1. n . A reverse-image contact copy of a positive, useful for checking
revisions of a PCB. If the negative of the current version is
superimposed over a positive of an earlier version, all areas will be
solid black except where changes have been made. 2. adj . (Of a PCB
image) Representing copper (or other material) as clear areas and
absence of material as black areas. Typical of power and ground planes
and solder mask.
net
A collection of terminals all of which are, or must be, connected
electrically. Also known as a signal.
netlist
List of names of symbols or parts and their connection points which
are logically connected in each net of a circuit. A netlist can be
"captured" (extracted electronically on a computer) from a
properly prepared CAE schematic. .
node
A pin or lead which will have at least one wire connected to it.
NOM
Abbreviation for nominal
NOMINAL
Average value for a given measurement
O
open
Open circuit. An unwanted break in the continuity of an electrical
circuit which prevents current from flowing.
P
package
1) Decal or printed wiring board component. 2) A type of PCB component
which contains a chip and acts to make a convenient mechanism for
protecting the chip while on the shelf and after attachment to a PCB.
With its leads soldered to a printed circuit board, a package serves
as the electrical conduction interface between the chip and the board.
An example is a DIP .
PACKAGING AND INTERCONNECTING STRUCTURE (P&IS)
The generic term for a completely processed combination of substrates,
metal planes or constraining cores, and interconnection wiring used
for the purpose of mounting components.
panel
material (most commonly an glass/epoxy-copper laminate known as core)
sized for fabrication of printed circuit boards. Panels come in many,
many sizes, the most common being 12" by 18" and 18" by
24". Subtract 1/2" to 1" margins (check with your board
house) from the panel size to arrive at the space available for
printed circuitry.
panelize
1. To lay up more than one (usually identical)printed circuits on a
pans. Individual printed circuits on a panel need a margin between
them of 0.3". Some board houses permit less separation. 2. Lay up
multiple printed circuits (called modules) into a sub-panel so that
the sub-panel can be assembled as a unit. The modules can then be
separated after assembly into discrete printed circuits.
part
1. Component. 2. A decal in a PWB database or drawing. 3. A symbol in
a schematic.
passive component
A device which does not add energy to the signal it passes. Examples:
resistor, capacitor, inductor. (Contrast with active component .
PC board
Printed Circuit board .
PCB
Printed Circuit Board .
PCB database
All of the data fundamental to a PCB design , stored as one or more
files on a computer.
PCB design
1. The creation of artwork for the manufacture of bare PCBs. 2. The
artwork so created. 3. A computer database used to generate such
artwork as data files ( CAM files ). Also called PCB layout.
PCB designer
One who creates the artwork for printed circuit boards. For you
recruiters out there who are asked to find one, and for anyone else
interested, here is a plain English description for a Printed Circuit
Board Designer. Hint: It is not the same as an electrical engineer.
PCB design service bureau
A business engaged in PCB design as a service for others, especially
electrical engineers. The word bureau is French for desk, or office,
and this service is indeed performed from an office while sitting at a
desk. Also called PCB design shop.
PCMCIA
An acronym which means: "People Can't Memorize Computer Industry
Acronyms." Wait a minute. That's WRONG! Click here to find out
its true meaning: Personal Computer Memory Card International
Association
photoplotter
Device used to generate artwork photographically by plotting objects
(as opposed to copying an entire image at once as with a camera) onto
film for use in manufacturing printed wiring.
PI
Polyimide.( Also Pi)
pin
A terminal on a component, whether SMT or through-hole. [Derived from
its physical shape on through-hole components, which predated SMT.]
Also called lead.
PIN GRID ARRAY (PGA)
Dual-in-line package consisting of a leadframe encased with a ceramic
shell
pin-out
Pin-number assignment, the relation between the logical inputs and
outputs of an electronic device and their physical counterparts in the
PCB package. pin-outs will involve pin numbers as a link between
schematic and PCB design (both being computer generated files). In
more complicated packages, they may also involve pin names. Even for
devices with only two pins and no polarity, such as resistors, the
netlist extracted from a schematic will have a pin 1 and pin 2 for
each resistor, even though the schematic might not show a pin number
label as such. (The visibility in the schematic of the pin numbers can
be turned on or off at will, but the significance of the pin number
assignment is still there in the schematic and subsequently, through
the netlist extracted from it, the PCB database.) For CAD CAE
electronics to work at all, the pin-outs for the PCB database must
agree with the schematic.
PITCH
Pin to pin or lead terminal to lead terminal spacing
plasma
A highly-ionized gas containing an approximately equal number of
positive ions and negative electrons. Thus, as a whole it is
electrically neutral, though conductive and affected by magnetic
fields.
PLASTIC
A polymeric material used for encapsulation. Also known as mold
compound.
PLASTIC FLANGE MOUNT (PFM)
Through-hole package with a tab for thermal heat dissipation.
PLASTIC LEADED CHIP CARRIER (PLCC)
Plastic package designed for surface mounting with J-lead
configuration.
PLASTIC QUAD FLAT PACKAGE (PQFP)
Plastic package with leads extending from four sides in a gull lead
form.
plated-through hole
A hole in a PWB with metal plating added after it is drilled. Its
purpose it to serve either as a contact point for a through-hole
component or as a via.
Plastic Leaded Chip Carrier
An SMT chip package that is rectangular or square- shaped with leads
on all four sides. The leads are spaced at 0.050 inches, so this
package is not considered fine-pitch.
positive
n. A developed image of photoplotted film, where the areas selectively
exposed by the photo plotter appear black, and unexposed areas are
clear. Board houses work from positives, and a photo plotter produces
positives, thus one set of positives is all the film that is needed to
produce a printed wiring board. adj. (of a printed wiring image)
Representing copper as black areas and absence of copper as clear
areas. Typical of images of routed layers of a PWB.
PQFP
Plastic Quad Flat Pack. See QFP .
PRESS FIT (PF)
A round or elliptical package whose mechanical mounting area is
presses into the packaging interconnect structure or cold plate for
purposes of thermal and electrical connection.
PRIMARY SIDE
That side of the packaging and interconnecting structure that contains
the most or more complex component.
primitive
(Found in CAD software programs and documentation) 1. Some CAD
software documentation extends this term to mean any object in a CAD
database--graphics, text or otherwise; so this could be a group of
graphic objects if manipulated as a unit, eg. a PCB decal . It may
also mean an indivisible graphic object, i.e. a graphical object which
may have component parts, but which can not have those parts separated
out as individual entities. Examples of this in PCB CAD: wire segment,
route, pad or padstack. 2.Any geometric shape such as a circle,
polygon or square. 3. A function, operator, or type which is built
into a programming language (or operating system), either for speed of
execution or because it would be impossible to write it in the
language. Primitives typically include the arithmetic and logical
operations (plus, minus, and, or, etc.) and are implemented by a small
number of machine language instructions.
PRINTED BOARD
The general term of completely process printed circuit or printed
wiring configurations. It includes rigid of flexible, signal, double
and multilayer boards
printed circuit board
a flat plate or base of insulating material containing a pattern of
conducting material. It becomes an electrical circuit when components
are attached and soldered to it. The conducting material is commonly
copper which has been coated with solder or plated with tin or
tin-lead alloy. The usual insulating material is epoxy laminate. But
there are many other kinds of materials used in more exotic
technologies. Single-sided boards, the most common style in
mass-produced consumer electronic products, have all conductors on one
side of the board. With two-sided boards, the conductors, or copper
traces, can travel from one side of the board to the other through
plated-thru holes called vias , or feed-throughs. In multilayer
boards, the vias can connect to internal layers as well as either
side.
PRINTED WIRING
The conductive pattern intended to be formed on a common base, to
provide point-to-point connection of discrete components, but no to
contain printed components.
POST or STUD MOUNT (PM)
A package whose mechanical mounting device is a threaded stud,
threaded hole, or post for mounting to the packaging and interconnect
structure or cold plate.
PWA
Printed Wiring Assembly; same as PCB .
PWB
Printed Wiring Board; same as PCB .
Q
QFP
Quad Flat Pack, a fine-pitch SMT package that is rectangular or square
with gull-wing shaped leads on all four sides. The lead pitch of a QFP
is typically either 0.8mm or 0.65mm, although there are variations on
this theme with smaller lead pitches: TQFP also 0.8mm; PQFP tooled at
either 0.65mm (0.026") or 0.025" and SQFP at 0.5mm
(0.020"). Any of these packages can have a wide variety of lead
counts from 44 leads on up to 240 or more. Although these terms are
descriptive, there are no industry- wide standards for sizes. Any
printed circuit designer will need a spec sheet for the particular
manufacturer's part, as a brief descrition like "PQFP-160"
is inadequate to define the mechanical size and lead pitch of the
part.
QUARTER SMALL OUTLINE PACKAGE (QSOP)
Package with leads extending from 2 sides in a gull lead form. Lead
pitch is .635mm (.025 inches).
R
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 nest.)
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.
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.]
registration
See register .
RF
Radio Frequency.
rise time
the time required for an output voltage of a digital cirucit 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.
route
1. n. A layout or wiring of a connection. 2. v. The action of creating
such a wiring.
S
SAC4
Self-Aligned Controlled Collapse Chip Connect. A variation of C4
flip-chip technology. . PFEIFFER L, WEST KW, WONG YH ,Journal of the
Electrochemical Society (JES) Volume 134, Number 11, November 1987.
saturation
1. The operating condition of a transistor when an increase in base
current produces no further increase in collector current. 2. A
circuit condition whereby an increase in the driving or input signal
no longer produces a change in the output. 3. The condition when a
transistor is driven so hard that it becomes biased in the forward
direction. In a switching application, the charge stored in the base
region prevents the transistor from turning off quickly under
saturation conditions. 4. Generally, that state in which a
semiconductor device is conducting most heavily for a given applied
voltage. In many devices it is also a state in which the normal
amplification mechanisms have become "swamped" and
inoperative. [Graf]
schematic
A diagram which shows, by means of graphic symbols, the electrical
connections and functions of a specific circuit arrangement.
SEATING PLANE
A plane generated, when the package is at rest, between the bottom of
leads and the contact surface.
SECONDARY SIDE
That side of the packaging and interconnecting structure that is
opposite of the primary side.
short
Short circuit. 1. An abnormal connection of relatively low resistance
between two points of a circuit. The result is excess (often damaging)
current between these points. Such a connection is considered to have
occurred in a printed wiring CAD database or artwork anytime
conductors from different nets either touch or come closer than the
minimum spacing allowed for the design rules being use.
SHRINK DUAL-IN-LINE PACKAGE (SDIP)
Package designed with leads for through-hole mounting. Lead pitch is
1.78mm (.070 inches).
signal
1. A net. 2. A net other than a power or ground net.
silicon wafer
a thin, iridescent, silvery disk of silicon which contains a set of
integrated circuits, prior to their being cut free and packaged. A
silicon wafer will diffract reflected light into rainbow patterns and,
being a similar size, looks so much like a music CD that it could be
mistaken for one (except that it has no label or hole in the middle).
On closer inspection, one can see the individual (usually rectangular-
or square-shaped) integrated circuits which form a uniform patchwork
quite unlike the surface of a music CD. When cut or etched from the
wafer these circuits are then called chips or dice.
silkscreen
(Also called "silkscreen legend") 1. The decals and
reference designators in epoxy ink on a printed wiring board, so
called because of the method of application the ink is "squeegeed"
through a silk screen, the same technique used in the printing of
T-shirts. The silk mesh size commonly used is 6 mils. Thus, the
absolute minimum line width of any silkscreen legend artwork is 6
mils, which leaves a very faint line. 7 mils works better for a
practical minimum line width. 2. A Gerber file controlling the
photoplotting of this legend.
single track
PCB design with only one route between adjacent DIP pins.
SMALL OUTLINE (SO)
A low-profile rectangular surface-mount component package. Its chip
(die) is bonded to an inner land contact area, primarily a lead frame.
SMD
Surface Mount Device (SMT component).
SMT
Surface Mount Technology.
soft
Pertaining to or consisting of software.
soft copy
An electronic form of a document; a data file in computer memory or
stored on storage media. When one is looking at a soft copy he is
viewing the document as displayed on a computer monitor.
software
Programs, data files, procedures, rules, and any associated
documentation pertaining to the operation of a computer system or of a
computer application.
solder bumps
The round solder balls bonded to a transistor contact area and used to
make connection to a conductor by face-down bonding techniques.
solder mask
A technique wherein everything on a circuit board is coated with a
plastic except 1) the contacts to be soldered, 2) the gold-plated
terminals of any card-edge connectors and 3)fiducial marks.
space transformer
Abbreviated ST. A major component of certain high-density probe cards
. It provides pitch reduction, high routing density and localized
mid-frequency decoupling. A major developer of ATE systems which use
space transformers is Wentworth Labs. .
SPECIAL-SHAPE PACKAGE
A miniature component package whose devices require a special shape.
Its terminals may project from one or more surfaces.
sputtering
A deposition process wherein a surface, or target, is immersed in an
inert-gas plasma and is bombarded by ionized molecules that eject
surface atoms. The process is based on the disintegration of the
target material under ion bombardment. Atoms broken away from the
target material by gas ions deposit on the part (substrate), forming a
thin film. [Graf]
SQFP
Shrink Quad Flat Pack. See QFP .
ST
Space Transformer .
stable datum
a datum along which all other data align. From any confusion, order
and sanity can emerge providing one merely selects a datum, assigns it
importance or seniority and then begins to align other data against
it. The stable datum for any PCB layout could be stated this way: The
schematic is the "Bible." In other word, the schematic says
the circuit is this way, and the PCB design must follow that pattern
perfectly.
STATIC ELECTRICITY
An electrical charge that has accumulated or built up on the surface
of a material.
STATIC ELECTRICITY CONTROL
A technique where materials and systems are employed to
eliminate/discharge static electricity buildup by providing continuos
discharge paths.
Streamline
v. Cause to be quick and efficient. Streamlined design = accuracy plus
speed. Streamlined Design, or SLD, is a set of policies that guide my
design of printed circuit boards. The policies have been derived with
the aim of simplifying and systematically eliminating errors from PCB
design.
stuff
Attach and solder components to (a printed wiring board).
sub-panel
A group of printed circuits (called modules) arrayed in a panel and
handled by both the board house and the assembly house as though it
were a single printed wiring board. The sub-panel is usually prepared
at the board house by routing most of the material separating
individual modules, leaving small tabs. The tabs are strong enough so
that the sub-panel can be assembled as a unit, and weak enough so that
final separation of assembled modules is easily done.
substrate
The supporting material on or in which the parts of an integrated
circuit are attached or made. The substrate may be passive ( thin film
, hybrid ) or active ( monolithic compatible). [For more information
see Modern Dictionary of Electronics, by Rudolf F. Graf.]
surface mount
Surface mount technology. The technology of creating printed wiring
wherein components are soldered to the board without using holes. The
result is higher component density, allowing smaller PWB 's.
Abbreviated SMT.
SUPPORTED HOLE
A hole in a printed board that has its inside surface plated or
otherwise reinforced.
SUPPORTING PLANE
A planar structure that is a part of a packaging and interconnecting
structure to provide mechanical support, thermo-mechanical constraint,
thermal conduction and/or electrical characteristics.
symbol
A simplified design representing a part in a schematic circuit
diagram.
T
TAB
Tape Automated Bonding.
tented via
a via with dry film solder mask completely covering both its pad and
its plated-thru hole. This completely insulates the via from foreign
objects, thus protecting against accidental shorts, but it also
renders the via unusable as a test point. Sometimes vias are tented on
the top side of the board and left uncovered on the bottom side to
permit probing from that side only with a test fixture.
TDR
Time Domain Reflectometer, a device which a board house can use for
measuring characteristic impedance of a conductor on a printed board,
thus insuring an accurate build for controlled impedance.
terminal
A point of connection for two or more conductors in an electrical
circuit; one of the conductors is usually an electrical contact, lead
or electrode of a component.
terminal block
a type of header to which wires are attached directly instead of by
means of a connector plug. Each wire is inserted in a hole in the
terminal block, and then anchored by means of a screw.
test coupon
An area of patterns on the same fabrication panel as the PWB, but
separate from the electrical circuits and outside the actual board
outline. It is cut away from the printed wiring board prior to
assembly and soldering of components. It can be used for destructive
testing.
THERMAL EXPANSION MISMATCH
The absolute difference in thermal expansion of two components.
thin film
A film of conductive or insulating material, usually deposited by
sputtering or evaporation, that may be made in a pattern to form
electronic components and conductors on a substrate or used as
insulation between successive layers of components. [Graf]
through-hole
(Of a component, also spelled "thru-hole"). Having pins
designed to be inserted into holes and soldered to pads on a printed
board. Contrast with surface mount .
thru-hole
Same as through-hole.
TMG
Tool Metrology Gauge (Depth & Runout - CNC-7)
TMS
Tool Management System (1 or 2 Cassettes/Spindle)
TQFP
Thin Quad Flat Pack. Essentially the same as a QFP except low-profile,
that is, thinner.
trace
Segment of a route .
track
Trace .
Trillium
A company that makes DUT or ATE systems.
TSI
Tool Status Indicator (Microwave)
TTL
Transistor-Transistor Logic. Also called multiple-emitter transistor
logic. A widely used form of semiconductor logic. Its basic logic
element is a multiple-emitter transistor. TTL is characterized by
fairly high speed and medium power dissipation. [Graf]
U
UL
Underwriter's Laboratories, Inc., a corporation supported by some
underwriters for the purpose of establishing safety standards on types
of equipment or components.
UNCASED CHIP (UC)
An uncased microminiature chip (die). Usually the chip has bonding
pads, bumps, ect. That are bonded to pads or lands on a lead-frame,
tape, or substrate.
unsaturated logic
A form of logic containing transistors operated outside the region of
saturation, which makes for very fast switching. An example is
emitter-coupled logic ( ECL ). (For other definitions and examples see
[Graf].)
V
Valuable Final Artwork
A term used in "Streamlined_PCB_Design :" Artwork for
electronic circuits which have been laid out and documented in forms
perfectly suited to the photo-imaging and numeric-controlled tooling
processes of printed circuit manufacture. It is termed
"final" because it has been thoroughly checked for errors
and any corrected as needed and is now ready for manufacture without
further work by the PCB designer . It is valuable because it can be
exchanged with a customer for money. Abbr. VFA. [Based on
"Valuable Final Product ," or "VFP," a term coined
by L. Ron Hubbard]
vcc or VCC
A name for a power net meaning "voltage collector," usually
+5V for TTL circuits.
vdd or VDD
A name for a power net meaning "voltage drain," usually
implying a more positive voltage.
vector photoplotter
(also "vector plotter", or "Gerber photoplotter"
after Gerber Scientific Co., which built the first vector
photoplotters for commercial use) It plots a CAD database on
photographic film in a darkroom by drawing each line with a continuous
lamp shined through an annular-ring aperture, and creating each pad by
flashing the lamp through a specially sized and shaped aperture. The
"apertures" are thin trapezoidal pieces of plastic which are
mostly opaque, but with a transparent portion that controls the size
and shape of the light pattern. The apertures are mounted on an
"aperture wheel" which can hold up to 24 apertures. Gerber
photoplotters, if set up by an experienced craftsman, are well-suited
for printed circuit artwork generation. Compare with laser
photoplotter , which is faster and has largely replaced the vector
photoplotter. There are still vector photoplotters in use. Some
manufacturers take advantage of the large bed size of the largest
Gerber photoplotters, roughly the size of a full-sized billiards
table. This enables the production of very large photoplots. An
example is Buckbee-Mears, which makes large antenna boards, and the
USGS (United States Geological Survery) which has used them in
map-making.
vee or VEE
A name for a power net meaning "voltage emitter," usually
-5V for ECL circuits.
VERTICAL SURFACE-MOUNT PACKAGE
A surface-mount package intended to be mounted perpendicular to the
seating plane. Terminals are located in one or more parallel rows.
via
Feed-through. A plated-through hole in a PWB used to route a trace
vertically in the board, that is, from one layer to another.
VLSI
Very Large Scale Integration.
VME
VMEbus is a computer architecture. The term 'VME' stands for
VERSAmodule Eurocard. The term 'bus' is a generic term describing a
computer data path, hence the name VMEbus
VQFP
Very thin Quad Flat Pack.
vss or VSS
A name for a power net meaning "voltage source," usually
implying a more negative voltage.
W
wafer
See silicon wafer .
WIP
Work In Progress. [Usage at Golden Gate Graphics: wip is used as the
extension of the name of a folder or sub-directory which groups data
in temporary storage locations for current "work in
progress." Any folders beneath the .WIP folder in the directory
structure would be named for the software, company and job in that
order. Eg: pclayout.wip/Cadstar/AcmeInc/A2Dboard ]
wire bonding
The method used to attach very fine wire to semiconductor components
(dice) to interconnect these components with each other or with
package leads. The wires might be 1 to 2 mils in diameter and made of
aluminum containing 1% silicon.
wet solder mask
Applied by means of distributing wet epoxy ink through a silk screen,
a wet solder mask has a resolution suitable for single-track design,
but is not accruate enough for fine-line design.
wire
Besides its usual definition of a strand of conductor, wire on a
printed board also means a route or track .
wire wrap area
A portion of a board riddled with plated-through holes on a 100-mil
grid. Its purpose is for accepting circuits which may be found
necessary after a PWB has been manufactured, stuffed, tested and
debugged.
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