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Acid
Trap: |
Vee section of laminate where two tracks are joined at an acute angle.
In the days of old with dip processing etchent could remain trapped
under the resist. |
Apertures:
|
Gerber files consist of instructions to take specific shaped "pens" and draw particular lines or curves with them. The "pens" are
called apertures. In the old days, they were actual templates which
would be placed in front of a light, the light switched on, and wherever
the light passed through the shape, it would be recorded on the film.
These days, it's all done by a sort of high-end laser printer, but the
model of an aperture and a path to sweep it along is still used. Most
apertures are simple geometric shapes such as circles and squares.
|
Artwork:
|
Traditionally 2:1 or larger, master pattern of the board.
Originally drawn using Indian ink or laid out using black paper
tape. Term now may refer to 1:1 films.
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Back Etching:
|
Chemical removal of substrate beneath a pad, only normally used
on flexible circuits.
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Backing
Board:
|
Sacrificial sheet of laminate used on the outside of drilling
stack to reduce both exit and entry drilling burrs.
|
Base
Laminate:
|
Insulating substrate out of which boards are made.
|
BBT Bare Board
Testing: |
Using
a bed of nails to electrically test for open/short circuits. |
BGA: |
Ball
Grid Array. |
Blind
via: |
A blind via is hole that reaches one outer surface, but
stops partway through the board (like a blind alley). |
Bomb
Sights:
|
Alignment targets used for aligning circuit layers.
|
Bonding:
|
Pressing and fixing together of the layers used to make a muli
layer PCB.
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Bowing:
|
Name given to a bent circuit.
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Bridging:
|
Unwanted short causing electrical short circuit.
|
Buried
via: |
A buried via is an
internal hole that doesn't reach either external surface. |
Burnt
Plating:
|
Grainy rough effect caused by using too high a plating current.
|
B.V.H.
|
Buried Via's, a via buried within a multi layer board.
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Clearance:
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Name for the isolating gaps between pads and tracks.
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Component
Side:
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Side of board onto which components are mounted.
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Contact
Print:
|
A direct 1:1 film copy normally made emulsion to emulsion.
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Corner
Marks:
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Extra tracks used to mark the corners of the circuit board.
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Coupon:
|
Small extra section added on to outside edge of board used for
destructive testing.
|
C/R:
|
Component reference.
|
Datum
Hole:
|
Master reference hole from which all other dimensions are
measured.
|
Dielectric
Constant |
Electrical
properties of PCB insulator (for RF designs) |
Direct
Metallisation:
|
Process used to make the non conductive areas conductive to
enable pattern plating of circuit boards.
|
Drill
File:
|
File generated by CAD systems, used for programming NC drilling
machines.
|
Drill
Tape:
|
Roll of paper with holes punched in it once used for programming
NC machines.
|
Dry
Film:
|
UV sensitive film laminated on and used to transfer circuit
pattern onto circuits. Other types can also be used to apply solder
resist.
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Earth
Plane:
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Name given to large area of copper. Often used to provide
electrical screening and control the characteristic impedance of
signal tracks.
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Electroless:
|
Type of solution used to deposit metal by chemical reactions
alone. Slow deposition rates only.
|
Electrolytic:
|
Type of solution used to plate metals using an electric current.
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Emulsion:
|
Name given to the active and delicate side of photographic film.
|
Etch-back:
|
Process where the substrate is chemically cut back inside holes
on a multi layer board. It promotes a better connection to the inner
layers.
|
Etch
Factor:
|
The ratio of etch depth to the amount the resist is undercut
during etching.
|
Etching:
|
Chemical removal of metals.
|
Extraneous
plating: |
Plating where you don't
want it, - on solder mask, on bare laminate, etc. |
Eyeballing:
|
Setting up the alignment of the films to the panels by eye.
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Flexible:
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A board made from flexible material.
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Flexi-rigid:
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A board made with both flexible and rigid material.
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Footprint:
|
Name given to specially shaped pad custom designed to accommodate
surface mount components.
|
FR2:
|
Flame retardant phenolic resin laminate with paper reinforcing.
|
FR3:
|
Flame retardant epoxy laminate with paper reinforcement.
|
FR4:
|
Flame retardant version of the old G10 epoxy laminate with glass
fibre reinforcement.
|
FR5:
|
High temperature version of FR4 epoxy laminate with glass fibre
reinforcement.
|
Gerber/Photoplot
File:
|
File format used to produce PCB artwork or tooling.
|
Glass
Transition Temperature:
|
Temperature at which the resin changes state from solid and
becomes very flexible.
|
G10: |
Tradition
std non flame retardant epoxy laminate, mostly replaced by FR4. |
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HASL:
|
Hot air solder levelling, involves coating the conductors with
molten solder then blowing off the excess with a hot air knife.
|
Hot
Oil Reflow:
|
Process where boards are immersed in a hot oil like mixture to
fuse electroplated Tin/lead.
|
Ident:
|
Another name to describe the component identification layer.
|
Immersion Tinning |
Process by which the
copper tracks and pads on a circuit are 'pre-soldered' with a layer of
tin, aiding in corrosion/oxidation prevention as well as quick
component take-up and dry joint reduction. |
IMS: |
insulated metal substrates. |
Jig:
|
Frame used for holding panels during plating operations.
|
Laminate:
|
Base material that a circuit board is made from.
|
Land:
|
Name given to the area of metal surrounding a hole.
|
Landless
Hole:
|
Name for a hole that doesn't have a pad surrounding it.
|
Legend:
|
Component reference, usually screened ink used to identify
components on board.
|
Markers:
|
Tracks marking outer edge of circuit board. Boards can often have
their profile described as cut to markers.
|
ML:
|
Multilayer board, circuit board with extra layers of tracks.
|
Mother
Panel:
|
Name given to a panel with duplicate circuits on it.
|
Negative:
|
Film where clear areas would represent tracks or legend on a
board.
|
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Organic
Coating:
|
Lacquer like coating applied to the bare circuit board copper to
prevent surface oxidisation.
|
Organic
Metal:
|
Conductive version of an organic coating, usually sold with a Electroless
tin top coat.
|
O.S.P. |
Organic solderability
preservative |
Pad:
|
Name for the metal annulus
on a board around a hole;
|
Panel
Plating:
|
Where the whole panel is plated with a metal;
|
Paper:
|
Term used to describe FR2 phenolic laminate.
|
Pattern
Plating:
|
Where only the required tracks and pads are plated with a metal;
|
Peel
Strength:
|
Measure of the adhesion of the copper to the laminate.
|
Photo-Resist:
|
Light sensitive resist used to transfer track pattern onto panel.
|
Pilot
Hole: |
Either
a small hole to ease or guide the path of a larger drill, or can be
the Entry and exit holes for routing which include pips. |
Plasma
Etch:
|
Process using ionised gas plasma to remove unwanted resin smear
from the inside of holes.
|
Plip:
|
Name used to describe connection lugs on a routed panel.
|
Polyester:
|
Low melting point plastic film used in flexible circuits.
|
Polyimide:
|
Higher melting point plastic film used in flexible circuits.
|
Positive:
|
Film where black areas would represent tracks or legend on a
board.
|
Power
Plane:
|
Similar to Earth plane but used as a large copper area to connect
a power supply rail to the components.
|
Prepreg:
|
Thin sheets of epoxy impregnated glass cloth used to bond multi
layer board.
|
PTH:
|
Plated-Through Holes. [Circuit boards where the tracks on both sides are interconnected
using plated holes.]
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Reflow:
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Heat up the board to melt/fuse the tin-lead covering the
tracks.
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Registration:
|
Describes the layer to layer alignment on the circuit
board.
|
Reversal
Print:
|
Film copy with the same polarity as the original but with
the emulsion side reversed.
|
Robber
Bars:
|
Extra areas of metal added outside the board area. Used to
reduce the risks of burning during electrolytic plating.
|
Roller
Tinning:
|
Application of the solder using a roller rotating in small vat of
molten solder.
|
Routing:
|
Drill like tool used to profile and cut out large holes, and
slots.
|
Roving Probe: |
Same
as BBT but carried out using only a few test probes which are
mechanically moved around the board. |
RS-274D
|
Name given to old style Gerber photo plotter format.
|
RS-274X
|
Name for Newer format of Gerber photo plotter language, includes
imbedded aperture tables amongst other things.
|
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Scoring:
|
V cuts made top and bottom to allow individual circuits to be
broken out of a mother panel.
|
Skip
plating: |
Missing plating where you
do want it - on copper pads,etc. |
Slivering:
|
Breaking away of the tin/lead edges when a track has been
undercut during etching.
|
Smear
Removal
|
Chemical removal of the resin smear inside a drilled hole.
Failures in this process would result in poor quality hole plating.
|
SMOBC |
Solder Mask Over Bare
Copper. |
Soda
Strawing:
|
Small pocket air pocket located along a track edge, trapped under
the solder resist.
|
Solder
Resist:
|
Coating applied onto surface to decrease the likely hood of
solder bridges during soldering. Or simply used to make circuit
boards look more aesthetically pleasing to the eye.
|
Spotting
In:
|
Touching up to remove flaws from both photographic masters and
the printed circuit pattern.
|
S/R:
|
Abbreviation for Solder resist.
|
Teardrop:
|
Flaring (widening) of the track as it approaches a pad, forming a teardrop shape.
|
Tooling
Hole:
|
Hole used by board manufacturer both to align track layers and
drilling.
|
Track:
|
Electrical route, connection linking pads.
|
Twist:
|
Another term for a bent board.
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Two
Pack:
|
An ink which is epoxy based, with separate
catalyst and resin components. Very tough when cured.
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A
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Unclad:
|
Laminate which has been made without any outer layers of copper.
|
UV
Inks:
|
Inks which are hardened using high intensity ultra violet light.
|
Via:
|
Small hole used solely to interconnect tracks on different layers
of the circuit.
|
Wave Soldering |
Soldering
joints by passing them over a wave/fountain of molten solder. |
|
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