原创 LAYOUT常用名词

2006-10-24 17:54 26437 11 12 分类: PCB

Index
1
Layout Glossary
active layer
In Layout, the design layer that is currently selected or visible on the screen.
algorithm
A procedure for solving a problem, usually mathematical.
analog circuit
A circuit comprised mostly of discrete components (resistors, capacitors, and transistors) that
produces data represented by physical variables such as voltage, resistance, or rotation.
annular ring
A circular strip of conductive material that surrounds a hole on the printed circuit board.
ANSI
Acronym for American National Standards Institute, an organization formed by industry and the
U.S. government to develop trade and communication standards. Internationally, ANSI is the
American representative to the ISO (International Standards Organization). See also ASCII.
anti-copper
An area within a fill zone in which copper cannot be placed.
aperture
A hole, similar to the aperture of a camera, that is used for photoplotting. Apertures are available
in various sizes and shapes.
aperture list
A text file containing the dimensions for each of the apertures used to photoplot PCB artwork.
arc
A segment defined as an arc (a portion of a circle).
arrow keys
On your computer keyboard, the keys you use to navigate around your screen. Each key is
marked with an arrow and is named for the direction in which the arrow points. There is an up
arrow, down arrow, left arrow, and right arrow key. Also known as direction keys .
ASCII
Acronym for American Standard Code for Information Interchange, a seven-bit code—based on
the first 128 characters of the ANSI character set— that assigns numeric values to letters of the
alphabet, the ten decimal digits, punctuation marks, and other characters such as Backspace,
Carriage Return, and Line Feed. ASCII is the most widely used character-coding set and, as
such, enables different applications and computers to exchange information.
assembly drawing
A document that relates information pertaining to the manufacture of a printed circuit board. This
information may include the board outline, component outlines and reference designators, part
values, and other documentation.
attribute
See property.
autodimension
In Layout, a tool for measuring and documenting the dimensions of your PCB design.
Index
2
AutoDFM
Acronym for automatic design for manufacturabil ity. Layout checks the board to ensure that it
meets manufacturability requirements. This feature automatically smoothes, miters, and checks
for both aesthetic and manufacturing problems that might have been created in the process of
routing.
AutoECO
Acronym for automatic engineering change order. AutoECO is a Layout command that enables
you to forward annotate a printed circuit board from Capture (or another design capture package)
to Layout.
automatic component placement
Software that automatically optimizes component placement on a printed circuit board.
automatic dimensioning
A computer-aided drafting function that automatically generates dimensions, leaders,
arrowheads, and other similar items that make up a complete set of documented dimensions.
autorouting
Automatic routing performed by a computer application based on a set of rules called strategies.
axial leads
Leads coming out the ends and along the axis of a resistor, capacitor, or other axial part, rather
than out the side.
back annotate
In Layout, to send data, such as component renames and gate and pin swaps, back to the
schematic.
BCD
Acronym for binary coded decimal.
BGA
Acronym for Ball Grid Array. Leadless array packaging technology in which solder balls are
mounted to the underside of the package and are flowed for attachment to printed circuit boards.
blind via
A via that reaches only one surface layer on one side of a multilayered PCB. See also via.
block
A specific portion of the board design that is marked and manipulated as a s ingle entity.
board template
A file that contains a board outline and some design rules. It may also contain drawing formats,
dimensions, preplaced components, and tooling holes. See also technology template.
buried via
A via that does not reach a surfac e layer on either side of a multilayered PCB. See also via.
CAD
Acronym for computer-aided design. Software used for general or specialized design uses for
architectural, mechanical, or electrical design.
CAE
Index
3
Acronym for computer-aided engineering. Softw are for analyzing designs created on a computer
or elsewhere and entered into the computer. Engineering analysis includes, but it not limited to,
structural or electronic circuit analysis.
CAM
Acronym for computer-aided manufacturing. Software used in all development phases of an
information system including analysis, design and programming.
centroid
Center of mass.
clusters
Components that are grouped according to their interrelationships and placed in close proximity
on the board. This keeps the connec tions on the PCB short so that the board is easier to work
with.
COB
Acronym for chip on board. Component packaging technology in which bare integrated circuits
are attached directly to the surface of a substrate and interconnected to the substrate most often
by means of microscopic wires.
component
An element or a part. PCBs are made up of components affixed to a common surface and
connected by copper tracks. See also footprint.
component density
The quantity of components on a unit area of a printed circuit board.
component hole
A hole in the printed circuit board that corresponds to a pin or wire of a component. This hole
serves the dual function of attaching the component to the board, and establishing the electrical
connection between the pin or wir e and the remainder of the board circuitry.
component library
A Layout file that contains the footprint patterns for a number of components.
component side
The uppermost layer of a board on which most components are placed. In Layout, the component
side of the board is nicknamed TOP and is layer number 1. See also solder side.
component silkscreen
The silkscreen markings of the printed circuit board that appear on the component side. The
silkscreen is applied over the solder mask.
component solder mask
The colored, usually translucent, coating applied to the board over the etched copper. It protects
selected copper from the soldering process.
connection
An unrouted, partially routed, or completely routed path between two pads. In a net with n pads,
there are exactly n–1 connections.
copper pour
A method by which a copper zone is filled with a specified pattern, avoiding objects that cross the
zone or lie within the zone.
Index
4
copper zone
An area on a board designed to be covered by a layer of copper when ma nufactured. Also known
as a metal zone.
cross hatching
The breaking up of large conductive areas by the use of a pattern of lines and spaces in the
conductive material.
cross probing
When intertool communication is enabled in Capture, selecting objects in Capture causes the
corresponding objects to be highlighted in Layout. Also, selecting objects in Layout causes the
corresponding objects to be highlighted in Capture. Both applications must be open. See also
intertool communication.
current layer
See active layer.
datum
A specific location (a point) that serves as a reference to locate a printed circuit board pattern or
layer for manufacture.
default
A parameter whose value is preset in Layout.
density
On a printed circuit board, the degree to which c omponents are packed on the board. Generally,
the density is given as the number of square inches per equivalent IC; a lower number indicates a
more dense board.
design rule
A guideline that specifies any of a number of parameters for the printed circuit board. These may
include minimum clearance between items that belong to different nets, or connection rules. Also,
these rules may include specifications for track width to carry a given current, maximum length for
clock lines, termination requirements for signals with fast rise and fall times, and so on.
Design Rules Check (DRC)
A feature that checks the PCB layout for violations of pad and track isolations.
design rule checking
The use of an algorithm to perform continuity verification of all conductor routing in accordance
with appropriate design rules.
DFM
See AutoDFM.
discrete components
Components with three or fewer electrical connections (for example, resistors or capacitors).
dispersion
See fanout.
# DRC
Index
5
See Design Rules Check.
drill chart
A table that appears on the DRLDWG layer of the board showing the current counts, locations,
and sizes of the holes to be drilled into the PCB.
drill diameter
The actual size of the drill body.
DXF
A graphics format created by AutoCAD.
ECL
Acronym for Emitter-Coupled Logic. A type of bipolar transistor that has extremely fast switching
speeds.
EDA
Acronym for Electronic Design Automation. Software and hardware tools used to ascertain the
viability of an electronic design. These tools perform simulation, synthesis, verification, analysis,
and testing of the design.
EDIF
Acronym for Electronic Design Interchange Format. A standard published by the EIA (Electronic
Industries Association) that defines the semantics and syntax for an interchange format that
communicates electronic designs.
editor
A tool used to create or modify a design or text file.
EIC
Acronym for Equivalent Integrated Circuit. A standard method for determining the number of
components on a board. The EIC is determined by taking the number of component pins on the
printed circuit board and dividing by 16.
electrical check
The process of checking the printed circuit board to ensure that the connections thereon match
those specified in the netlist.
Extended Gerber
See Gerber (274-X).
fanout
The process of creating dispersion vias for SMT devices on your printed circuit board. The
dispersion vias are connected to SMT devices by via stringers.
feed-through hole
See via.
fill zone
A zone that defines an area to be filled by copper. See also copper pour.
fine pitch
A class of surface-mount components that is characterized by pins that measure 0.025 inches or
less from pad center to pad center.
footprint
Index
6
The physical description of a component. It consists of three elements: padstacks, obstacles, and
text.
forward annotation
The process of sending netlist data in the form of an .MNL file from Capture (or other schematic
capture application) to Layout.
FPGA
Acronym for Field Programmable Gate Array. A logic chip that is programmable and has a high
density of gates.
free via
A free via and a normal via differ relatively little: they use the same padstack definition and serve
much the same purpose. Unlike a normal via, however, once you specify the location and
purpose of a free via it cannot be altered by Layout. Layout regards free vias as stand-alone
components: you can shove them, place them in isolation (free of tracks), or connect them to
multiple tracks on the same net.
Free vias must have a net attachment, though they do not appear in a schematic or netlist. They
are preserved through AutoECO, unless the net or routed track they are connected to is entirely
deleted or removed from the board. Free via matrices connected only by unrouted connections
are never removed by AutoECO unless the entire net is removed from the board.
You can use free vias for special purposes, such as zero length fanouts of ball-grid array
components and the "stitching" of plane layers. Test points can be thought of as free vias that use
a test-point padstack.
FTP
Acronym for File Transfer Protocol , which is a highly reliable file transfer protocol that is used
almost exclusively over the Internet. FTP should be used for both binary and ASCII transfers.
However, data files should be transferred in binary format.
gate swap
The exchange of identically functioning gates in order to decrease route lengths.
Gerber (274-D)
A file format that can be read by Gerber and other photoplotter systems that require separately or
previously defined aperture lists.
Gerber (274-X)
A file format that can be read by Gerber photoplotters that accept embedded aperture lists. Also
known as Extended Gerber.
Gerber data
A type of data that consists of aperture selection and operation commands and dimensions in X
and Y coordinates. The data is generally used to direct a photoplotter in generating photoplotted
artwork.
Gerber photoplotting
A method of transferring PCB artwork to film.
Gerber table
The Gerber table is the plot area that will be output to Gerber. This area may include the board
and peripheral items such as the drill chart or comments.
global layer
Index
7
When you load a netlist file, Layout places all connections in the netlist on a global layer.
grid
In Layout, all design elements are placed on the board according to five grids: routing, via, dot,
place, and detail.
ground plane
An area on the printed circuit board, usually an entire layer, that provides a common ground
connection for all component ground pins and other ground connections.
heatsink
A mechanical device that is made of a high thermal-conductivity material that dissipates heat
generated by a component or assembly.
heuristics
A method of routing that consists of repeatedly attempting to apply very simple routing patterns to
unrouted connections in order to complete the routing quickly and cleanly. Typically, heuristics
are used for memory and short point-to-point routing.
highlight
Graphical emphasis that is given to text, components, or other objects when they are selected for
an action.
hole
In Layout, the areas where board material must be removed by drilling or milling.
hole legend
See drill chart.
HP-GL
Acronym for Hewlett-Packard Graphics Language, which is a plotter protocol developed by
Hewlett-Packard.
HP-GL2
An extension of HP-GL that supports polygon fills, wide lines, and other methods of plotting
complex shapes.
IC
Acronym for integrated circuit.
IGES
Acronym for initial graphic exchange specification, which is a graphics format for transferring
CAD/CAM information.
interactive routing
Routing in which individual connections are entered into the Layout design file manually by the
user with the aid of information such as ratsnests, DRC rules, or DFM rules.
intertool communication
A capability that allows tools to share information for display and transfer.
IPC
Acronym for Institute for Interconnecting and Packaging Electronic Circuits. An association in the
printed circuit board industry that provides standards to enhance commonality of designs.
isolation
Index
8
The clearance around a pad, track, zone, or via that defines the nearest approach allowed by
conductors of another signal set.
ITC
Acronym for intertool communication. See intertool communication. See also cross probing.
jumper wire
A discrete electrical component or wire that is used to make electrical connections between
points for which copper etch does not exist due to board density or some other factor.
keepout
An area fill within which no routing is allowed.
land
In Layout, the copper pad needed for a surface mount pin.
layer
One in a series of planes in a PCB design on which tracks are arranged to connect components.
Vias connect tracks and zones between layers. Layout allows a maximum of 30 layers, 16 of
which can be copper.
layer marker
An object on a board layer that indicates the layer’s physical number as counted from the top
layer. Used for copper layers only.
layout
A scale drawing of a printed circuit board, its components, and its electromechanical connections.
LCC
Acronym for Leaded Chip Carrier. A chip carrier that is square and contains pin connectors on all
four sides. Implementations include the PLCC (plastic LCC) and CLCC (ceramic LCC).
library
In Layout, a collection of footprint samples or templates designed to facilitate PCB design
creation.
line
A non-electrical drawing entity.
manual routing
Individual connections, in the form of traces, vertices, arcs, and so on, that are entered manually
into the PCB design.
matrix
In Layout, a tool that creates a structure on the board that can be divided into cells used for the
efficient placement of footprints.
MCAD
Acronym for Mechanical Computer Aided Design. CAD software specific to mechanical
engineering.
mixed component-mounting technology
A component-mounting technology that uses both through-hole and surface-mounting
technologies on the same printed circuit board.
Index
9
MNL
Acronym for MAX netlist. This is the netlist format that is accepted by Layout.
mounting hole
A hole used for the mechanical support of a printed board or for the mechanical attachment of
components to a printed board.
multilayer board
A printed circuit board that has multiple layers, separated by dielectric material, with connectivity
between layers established by vias or through-holes. This term usually refers to a board with
more than two layers.
net
A logical construct that originates in a schematic and is transferred to a board to describe
required electrical connections. The connections may be completed using vias, tracks, or zones.
See also track.
netlist
A file that lists the interconnections of a schematic diagram by the names of the signals, modules,
and pins connected together on a PCB. Also, the nodes in a circuit.
obstacle
An outline that represents an object on the board that must be taken into account during routing,
placement, or copper pour.
opaque graphics
In Layout, these are visual representations of objects on your printed circuit board. These objects
are represented in different colors if they occupy the same space in the board.
pad
On a PCB, a copper shape on one or more layers (there may be a hole and an isolation
surrounding the copper) used for connecting a component pin to the PCB. The pad indicates
where pins of a component are placed.
padstack
A numbered list of via stack descriptions. Each description contains a pad or v ia definition,
including layer, style, drill diameter, size, offset, and solder mask guard width.
pan
In Layout, the screen automatically scrolls to display successive sections of the board when you
move the mouse to the screen edge.
PCB
An acronym for printed circuit board.
PGA
Acronym for Pin Grid Array. A chip package with a high density of pins that is used for large
amounts of I/O.
pin
The portion of a component to which an electrical connection can be made.
pin swap
The exchange of identically functioning pins in order to decrease route lengths.
pin to pin spacing
Index
10
The physical spacing between pins on a device.
pitch
In reference to a component, the distance from the center of a pad to the center of an adjacent
pad.
placement
The position of components on a PCB. The process of selecting where components will reside on
a PCB.
plated through-hole
A through-hole that establishes an electrical connection between layers of a printed circuit board
by way of a metal deposition on the inner surface that defines the hole.
plane layer
A layer of copper that is dedicated to a single net and may have pads and holes that connect to it
or pass through it. Typically used for the power and ground layers, CAD tools output the Gerber
file for a plane layer in a negative form, meaning that the areas without copper are identified.
Regular copper layers are output in positive form, meaning that the areas with copper are
identified.
polar placement
The process of placing printed circuit board components using polar c oordinates referenced from
a user-define pole. Typically, this is used for test fixtures.
post processing
A term used to collectively describe the processes performed after the board has been routed in
order to produce manufacturing information (silkscreens, reports, drill tapes, assembly drawings,
and so on).
power plane
A copper layer dedicated to a signal that is considered to be a power supply. The ground plane is
a power plane that supplies the ground potential.
property
A characteristic of an object that can be edited. A property consists of a name and a value.
Examples of property names are part value and color. Their respective property values can be
something such as capacitor and red.
query
When you select an object on the screen, Layout displays the object attributes for viewing or
editing.
radial lead
A lead extending out the side of a component, rather than from the end.
ratsnest
A straight-line connection between two or more pads that indicates an electrical connection in the
netlist. Ratsnests serve as a reminder that the pads must be connected, and that, currently, there
is no track on the board to make that connection.
reference designator
A character string denoting the type of component and a number that is specific to that
component.
registration
Index
11
The alignment of a pad on one side of the printed circuit board (or layers of a multilayer board) to
its corresponding pad on the opposite side.
routing
Placing conductive interconnects between components on a PCB layout. The process of tur ning
nets into tracks.
scale
To enlarge or reduce a printed circuit board representation when printing or plotting.
schematic
A graphical description of an electrical circuit.
screen coordinates
The X and Y coordinates reporting the location of the cursor on the screen.
segment
The partial track that exists between two adjacent vertices or between a vertex and a pin.
(Sometimes the track between two pins is called a segment, although it is usually called a
connection.)
signal
An electrical impulse of a predetermined voltage, current, polarity, and pulse width.
silkscreen
Text or outlines (in ink) on the solder mask, on the top, and sometimes on the bottom of modules
for a board. Used for component and identification placement on a PCB.
SMD
Acronym for surface mounted device. A component that is mounted on a surface layer of a
printed circuit board, without penetrating the board. See also surface mount.
SMT
Acronym for surface mount technology. Printed circuit board technology in which the leads on the
chips and components are soldered on top of the board as opposed to through it. The use of SMT
results in smaller and faster printed circuit boards. See also surface mount.
solder mask
A negative plot of pads with a guard band around the pads. Also, a lacquer applied to prevent
solder from adhering to unwanted areas on the PCB.
solder paste
In Layout, a pattern that serves as a template for solder paste application when the board is
manufactured.
solder side
The printed circuit board surface opposite the one on which most components are mounted. Also,
the bottom layer of the board.
strategy file
A file that contains either placement or routing parameters for a specific type of board with a
specific layer structure.
surface mount
A component mounting technology in which holes are not required.
Index
12
technology template
A file that contains a board outline and the appropriate design rules, drawing formats, dimensions
for spacing and grids, preplaced components, and tooling holes for a specific type of board.
test point
A special point of access to an electrical circuit that is used for electrical testing purposes.
thermal relief
A means of connecting a pad to a larger copper area while minimizing the amount of copper
available to conduct heat during the soldering process.
thieving
The process of balancing the amount of copper on both sides of a board so that through-hole
plating is consistent from top to bottom during board fabrication.
through-hole technology
The process and components associated with producing a printed circuit board that employs
traditional through-hole components.
through-hole via
A via that connects the surface layers on a PCB. See also via.
thrucode
See padstack.
tooling hole
A tooling feature in the form of a hole in a printed board of fabrication panel.
trace
See track.
track
The copper trails in the PCB and the onscreen representation of that copper.
venting patterns
Patterns etched in the board that allow gases formed during fabrication to escape.
vertex
A logical point at which a track is ended and restarted. A vertex is located at each change of
direction on the track.
via
A hole connecting layers of a PCB. A through-hole via connects surface layers of a board. On
multilayer boards, a via not reaching a surface layer on one side is called a blind via, and a via
not reaching a surface layer on either side is called a buried via.
via stack
See padstack.
via stringer
The copper etch that exists between an SMT pad and a corresponding fanout via. See also
fanout.
X axis
The horizontal or left-to-right direction in a two-dimensional system of coordinates. The X axis is
perpendicular to the Y axis.
Index
13
Y axis
The vertical or bottom-to-top direction in a two-dimensional system of coordinates. The Y axis is
perpendicular to the X axis.
zero-length connection
An unrouted connection between layers where the end points in the connection have the same X
and Y coordinates. In Layout, these connections are flagged with yellow triangles.
zone
An area on a PCB layer designated as copper or anti-copper. Copper zones may have net
names, while anti-copper zones may not. See also copper pour.
zoom
To change the view of a window, making objects appear larger or smaller. When you zoom out,
objects are smaller, and you see more of the board. When you zoom in, objects are larger, but
you only see a small portion of the board. You can also zoom in or out of a print preview.

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用户35003 2006-11-2 22:18

有中文就好了

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