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Annular
ring often used to specify the copper wall plating thickness of holes
(recommended min. value is 2 mil). Some designers use this term when
referring to the pad size over the drill hole size (recommended min. value
is 18 mil).
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In
photoplotting, aperture list or D-Code assignments are used in defining
shapes and sizes of Gerber file entities.
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A drawing
that shows all parts identified by their reference designator (C1, R1, U1,
etc. like the silk-screened artwork), panel outline with datum and tooling
hole positions.
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Axial
leaded components are flat down type discrete components (i.e. resistors).
Assembly costs for axial leaded components (come in tape/reel form) are less
than radial leaded components.
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Beveling
refers to the 45 degree angle that makes finger contact edges smooth, thus
enabling easier insertion by the consumer.
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Ball Grid
Array, a leadless SMD developed in recent years. Unlike traditional SMDs,
this type of device does not have pin leads, instead it contains solder
balls at the bottom of the device. These solder balls melt and make contact
to the pattern on board.
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Bill of
Material. A component list with reference designators, part numbers, values,
tolerance, description and other information.
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A common
PCB panel format with board units connected to a panel by number of tabs
around the units. Units break-away from panel after assembly. Panel
profiling of this format may be routed or punched.
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PCB
material, both CEM-1 and CEM-3 are epoxy/fiberglass over a paper core,
differing only in the type of paper used. These materials are less
expensive, more punchable substitutes for FR-4. Not a military grade
material.
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Separation between circuit entities. Generally refer to pad-pad, pad-trace,
trace-trace, solder mask-pad, pad-drill, circuit-board edge, etc. These
clearances are critical for board manufacturability and they should be set
at maximum when design allows.
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A
spray-on, clear non-conductive coating that covers components and circuit
board to protect them against oxidation and from hazardous environments.
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copper pouring or copper hatch |
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CAD/CAM
terms: to fill an enclosed area (generally defined by 0-width polygon lines)
with a solid or hatch pattern to create a copper plane or a section of
copper plane.
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copper thickness and copper plating |
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Cooper
thickness usually specified in terms of number of oz/sq.ft (1/2 oz: 17.5um
or 0.0007"/sq. ft; 1 oz: 35 um or 0.0014"/sq. ft, and etc.). The thickness
of copper you specified will be the final thickness of base material plus
copper plating thickness.
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Clinch is
an operation where leads are bent at an angle after auto insertion to avoid
component pop-up during wave-soldering.
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In
photoplotting, D-Code assignment or aperture lists are used in defining
shapes and sizes of Gerber file entities.
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An NC
file containing tool and coordinate information for drilling. Common format
accepted are: EIA or Excellon in either binary or ASCII text file..
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Data
eXchange Format, commonly use in mechanical CAD systems.
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Electrical test or bare board test refer to PCB short/open test.
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electro-less gold plating |
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A gold
plating process as a substitution of regular Tin/Lead plating. This type of
plating applies a layer of thin gold (a fraction of micro-inches) to the
entire circuit.
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Electrical Rule Check to verify design violation against pre-set parameters
such as In/Out matching in schematic capture, or spacing rules in CAD/CAM
systems.
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A drawing
required for manufacturing. For circuit board fabrication, some times refer
to as drill drawing. A fabrication drawing should include: board outline and
cut-outs with datum and proper dimensions; sizes and locations of all
tooling holes, mounting holes.
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Fiducial
marks are dots etched on board panel usually required by SMD assembly
(provide viewing targets for camera to locate correct position).
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A
preserve agent for soldering. Old types of flux require cleaning process
after soldering. There is No-cleaning-flux available now and it is safe for
both circuitry and environment.
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General
purpose epoxy/fiberglass woven fabric PCB base material. FR-4 is similar to
G-10, but fire retardant. FR-4 is much more widely used than is G-10, and is
used where the material requirement calls for G-10. FR-4 is sometimes
referred to as G10FR.
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A test to
verify a product's behavior after components are mounted on board. The test
is performed according to a customer's specification and parameters
provided.
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General
purpose epoxy/fiberglass woven fabric PCB material. Most vendors do not
stock this material, instead, they use high grade material like FR-4 as a
substitution if you specify G-10.
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A CAD/CAM
data exchange format developed by IPC.
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A widely
accepted file format for photoplotting and as input to generate many format
of testing program and component placement program. There are two variants
in Gerber file format: 274-D and 274-X (also called the extended Gerber or
Gerber-X, with embed
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Generally
required for contact fingers. Common specifications for this plating are:
0.00002" gold over 0.00015" nickel.
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Teflon
resin over woven fiberglass PCB material. Used for circuits requiring very
low dielectric constants.
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Hot Air
Leveling, uses in conjunction with SMOBC (solder mask over bare copper),
plates solder on component pads only (instead of Tin-plated traces and pad
surface).
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HPGL is a
pen-plot format file generated from almost all CAD systems.
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Impedance
control refers to a dual process of designing and manufacturing of high
speed circuit boards. As the frequency of a circuit goes up to a certain
point (a few hundred Mega Hz), circuit traces will act as transmission lines
and require impedance matching.
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A test to
verify components' behavior after they have been mounted on a board.
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An
industrial grade quality standard for acceptance of PCBs.
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A CAD/CAM
data exchange format developed by IPC. Accepted by some CAM systems for use
of photoplotting, electrical testing and other CAM functions.
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Land
(same as pad), often refers as SMD Lands. SMD lands in most cases are
suggested by component manufacturers and generally have standard codes such
as 1206, SOT-23, SOIC14, etc. Consult component manufacturers or refer to
IPC docs: ANSI/IPC-SM-782 for more information.
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A
collection of part information including symbol, foot-print, pad-stack and
other cross reference information. Used in CAD/CAM EDA tools.
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Liquid
Photo-Imageble solder mask, as compared to traditional screen wet mask, LPI
has an advantage due to its precision. LPI generally has tighter
registration tolerance.
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A term
defining the ability of a board design to meet manufacturing requirements.
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See
"solder mask".
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A
military grade quality standard for acceptance of PCBs.
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A
military grade quality standard for design layout of PCBs
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PCB
layers are referred to as number of sides of copper foil used. A PCB with
one side of copper foil is called single-sided, with two sides of foil is
called double-sided. PCBs with more than 2 sides of copper are defined as
multi-layered.
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An ASCII
list describes logical connections between component pins. Generated from
schematic capture systems for transferring logical connections to layout
systems.
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A type of
hole on a circuit board generally used as mounting holes for the board. The
wall of these holes/slots are not plated thus no connection between layers.
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Pad
refers to copper contact for component lead, common shapes accepted are
round, square, rectangular, ob-round, and heat-relieved.
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In CAD
layout EDA systems, padstack is a collection of pad shape and size
information
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A general
term in CAM editing refers to step/repeat to prepare data in panel format.
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A common
type of solder mask which has a shiny lighter finish than SR-1000. Generally
available colors are: green, blue, red, white and black.
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photoplotting or photoplot |
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Photoplotting is an electronic optical process to scan rasterized image data
on films. Sometimes referred to as laser plotting. A photoplot is a film
generated by a photoplotter, or referred to as artwork required for PCB
fabrication.
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A type of
hole on a circuit board generally used to mount components and to create
vias. The wall of these holes/slots are plated forming a circuit between
layers.
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A PCB
panel format with board units punched out from the panel then reset back
into the same location by second operation.
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Radial
leaded components are standing type discrete components.
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Component
ID used in schematic and PCB design, such as C1, C2, R1, R2, etc.
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Registration refers to layer alignment of data, artwork, films, imaging
process, screening, lamination, drilling and routing.
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In a PCB
CAD layout application, routing refers to making manual/automatic wiring
connections to logical nodes in a net. In PCB fabrication, routing refers to
board edges profiling by running an NC program.
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An
assembly term referring to arrangement of axial/radial components in their
order of insertion sequence, and to prepare a new tape/reel by a sequencer.
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A legend
printing, or the legend of circuit boards.
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Solder
Mask Over Bare Copper, used in conjunction with HAL (hot air leveling),
denotes solder mask applied to bare copper (instead of to Tin-plated
surface). |
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A
non-conductive surface screened or laminated on the PCB to protect the
circuit from oxidation, and shorts during wave-soldering. Common solder mask
types available are: SR-1000, PC-103/4, LPI.
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Form of
solder to be printed on SMD pads by using a stencil in assembly.
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Component
span refers to the center-to-center lead spacing of axial and radial
components.
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A common
type of solder mask, with a darker mat finish than PC-103/4. Generally
available colors are: green, blue, red, white and black.
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Stencil
is a cooper foil screen with SMD pads etched openings used for solder paste
printing in assembly.
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step/repeat (step and repeat) |
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A general
term in phototooling refers to an image unit which is stepped and repeated
into multiple image units.
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This term
defines the ability of meeting electrical requirements.
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thermal relief or heat relief |
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A thermal
relief or heat relief is a type of circuit pad used at a location where
there is a component pin or fan-out via that connects to a copper plane.
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A type of
hole on a circuit board generally used for component pins and vias. The wall
of these holes/slots are plated creating a circuit between layers where
required.
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The most
commonly used solder plating process in the PCB industry. The process
appllies 0.0004"(min.) to 0.0008"(max.) of Sn/Pb on all conductive areas.
However, Tin-lead plating may not be a suitable a process if you have SMD on
the board.
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Tooling
holes are used at various points in the PCB fabrication, assembly and test
processes. These holes serve the purpose of holding PCB panels to fixtures
during manufacturing.
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Underwriters Laboratories, a recognized agent to test and approve electronic
processes for meeting the standards set by the organization. Most PCB
vendors are UL approved, but not many of them will print a UL logo on your
boards.
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A board
profiling process that involves cutting straight lines from both sides of
board. This profiling method is more time efficient than a traditional
routing process, suitable for medium to large volume production with panels
requiring only straight line routing.
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Interconnection between circuit layers. Common type of via connects traces
on all layers, blind via or buried via are connected to defined layers only.
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Warping
generally refer to finished board warp and twist. All boards may have a
certain degree of warp as a result of manufacturing, especially if materials
contain a high volume of moisture. Therefore you should specify your warping
tolerance.
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A machine
soldering process involving pre-heat, fluxing, soldering, and cleaning. Most
commonly used solder composition is 63%Sn/ 37%Pb.
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General
type of solder mask appllied by screen. Usually refers to types of solder
mask like SR-1000 and PC-103/4. LPI is NOT a type of wet mask.
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Zero
width represents an outline shape drawn by "0" thickness line width. The
most commonly used definition is the polygon to draw copper fill, or shapes
defining the drawing limit of an entity. |
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