IPC-T-50F_.pdf.pdf - 第77页
Waste (Fabric) 44.1564 A lump or collection of yarn or filament that is woven into a fabric where accumulated contamination of f the loom has found its way into the fabric. Water-Soluble Flux 75.1150 An organic chemical s…
Vapor-Phase Soldering 75.1557
A reflow soldering method that is based on the exposure of
the parts to be soldered to hot vapors of a liquid that has a
boiling-point that is sufficiently high to melt the solder
being used.
Variables Data 91.1134
Quantitative data where measurements are used for analy-
sis.
Variance 91.1135
A measure of dispersion that is equal to the square of the
average value of deviation from a mean value.
Vendor Inspection Lot (Material) 91.1558
All of the material of the same type that have been fabri-
cated within a specified period of time using the same pro-
cessing procedures and conditions that are offered for
inspection at one time.
Verification Time 91.1136
The time required to determine an anomalies location, to
evaluate it, and to classify it with respect to predefined cri-
teria.
Very Large Scale Integration (VLSI) 30.1559
Integrated circuits with more than 80,000 transistors on a
single die that are interconnected with conductors that are
1 micron or less in width.
Vesical 92.1137
A blister formed as the result of vesication.
Vesication 92.1560
The formation of blisters at the interface between a semi-
permeable polymer film coating another material caused by
an osmotic effect from the interaction of water soluble mat-
ter with moisture. (See also ‘‘Measling.’’)
Vesicativity Ratio 92.1561
The ratio of the degrees of vesication produced by a spe-
cific mass of a substance to the degree of vesication pro-
duced by the same mass of sodium chloride under the same
specific conditions.
Via 22.1562
A plated-through hole that is used as an interlayer connec-
tion, but in which there is no intention to insert a compo-
nent lead or other reinforcing material. (See also ‘‘Blind
Via’’ and ‘‘Buried Via.’’)
Virtual Condition 91.1138
The boundary generated by the collective effects of
maximum/least material condition limits of size of a fea-
ture and any applicable geometric tolerances.
Visual Examination 92.1139
The qualitative observation of physical characteristics with
the unaided eye or within stipulated levels of magnifica-
tion.
Void 90.1140
The absence of any substances in a localized area.
Voltage Plane 22.1563
A conductor layer, or portion thereof, that serves as a com-
mon voltage source at other than ground potential for an
electrical circuit, shielding, or heat sinking. (See also
‘‘Ground Plane’’ and ‘‘Signal Plane.’’)
Voltage Plane Clearance 22.1141
Removed portions of a voltage plane that isolate it from a
hole in the base material to which the plane is attached.
Volume Ratio (Composite) 41.1142
The proportional thickness of one component of a compos-
ite material to the total thickness of the composite.
Volume Resistivity 21.1143
The ratio of the electrical potential gradient parallel to the
current in a material to the current density, expressed in
Megohm-meters.
Volumetric Analysis 92.1144
The measurement of the volume of solution consumed in a
titration process.
W
Wafer 35.1145
A thin slice of semiconductor crystal ingot that is used as a
base material.
Waffle Pack 71.1146
An open compartmentalized container for holding surface-
mount components that is suitable for loading the compo-
nents into automatic handling equipment.
Warp 60.1147
see ‘‘Bow.’’
Warp Size 44.1149
Organic yarn binder (starch) applied to the warp yarn to
improve strand integrity, strength and smoothness in order
to withstand the rigors of weaving. (See also ‘‘Sizing’’ and
‘‘Heat Cleaning.’’)
Warper 44.1148
A machine for preparing and arranging the yarns intended
for the warp of the fabric.
IPC-T-50F June 1996
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Waste (Fabric) 44.1564
A lump or collection of yarn or filament that is woven into
a fabric where accumulated contamination off the loom has
found its way into the fabric.
Water-Soluble Flux 75.1150
An organic chemical soldering flux that is soluble in water.
Wave Soldering 75.1152
A process wherein an assembled printed board is brought
in contact with the surface of a continuously flowing and
circulating mass of solder.
Wave Length Spectrum 21.1776
The distance between three consecutive nodes of a wave,
equal to 360 electrical degrees. It is equal to the velocity of
propagation divided by the frequency when both are in the
same units.
Waveguide 21.1151
A tube used to transmit microwave-frequency electromag-
netic wave energy.
Waviness 44.1153
Alternating thick and thin locations in cloth that is woven
under varying tension that prevents the even placement of
picks.
Weave Exposure 55.1154
A base material surface condition in which unbroken fibers
of woven glass cloth are not completely covered by resin.
Weave Texture 55.1565
A surface condition of base material in which a weave pat-
tern of glass cloth is apparent although the unbroken fibers
of the woven cloth are completely covered with resin.
Web Taper 51.1155
The constant increase in web thickness from the drill point
to the opposite end of the flute where the flute carry-out
starts.
Web Thickness 51.1156
The distance between the bottom of adjacent flutes.
Wedge Bond 74.1157
A wire bond made with a wedge tool. (See also ‘‘Ball
Bond.’’)
Wedge Tool 74.1158
A bonding tool in the general form of a wedge, with or
without a guide hole to position wire under its bonding
face. (See also ‘‘Capillary.’’)
Wetting Balance 92.1160
An instrument that is used to measure wetting performance
and solderability.
Wetting, Solder 75.1159
The formation of a relatively uniform, smooth, unbroken,
and adherent film of solder to a basis metal.
Whisker 92.1161
A slender acicular (needle-shaped) metallic growth that is
between a conductor and a land.
White Spot 92.1566
A white or translucent subsurface discoloration at unfrac-
tured glass knuckles of woven polytetrafluoroethylene
(PTFE) material after it has been processed. (See also
‘‘Crazing’’ and ‘‘Measling.’’)
Wicking 75.1162
The capillary absorption of a liquid along the fibers of a
base material. (See also ‘‘Solder Wicking.’’)
Window 94.1163
A range of values within which evaluation parameters are
defined.
Window (Carrier Tape) 36.1164
An opening in the dielectric of a carrier tape that exposes
the conductors for bonding purposes.
Window (Process) 94.1165
A range of values within which evaluation parameters are
defined.
Wipe Soldering 75.1166
The forming of a joint by applying semifluid solder and
shaping the joint by rubbing with a greased cloth pad.
Wiping Action 37.1167
The sliding action that occurs when connector contacts are
mated.
Wire Bonding 74.1168
Microbonding between a die and base material, lead frame,
etc.
Wire Sag 74.1169
The failure of a wire to form the desired loop between its
bonds.
Wire Stripping 37.1567
The removal of a predetermined portion of insulation from
an insulated wire without affecting the mechanical or elec-
trical characteristics of the conductors or the remaining
insulation.
Wire Wrap 75.1170
see ‘‘Solderless Wrap.’’
June 1996 IPC-T-50F
73
Wiring Elementary 21.1171
see ‘‘Elementary Diagram.’’
Wobble Bond 74.1172
A thermocompression multicontact bond made by rocking
a bonding tool on a beam lead.
Working Master 24.1173
A 1-to-1 scale pattern that is used to reproduce the produc-
tion master.
Working Time 75.1568
The maximum period of time that an adhesive can be
exposed to ambient conditions with its chemical and physi-
cal properties remaining within satisfactory limits for
proper dispensing and bonding. (See also ‘‘Open Time.’’)
Wrinkles 76.1569
Ridges, creases or furrows in a coating or resist that are
formed after the material has adhered to a metal, such as
solder, that subsequently melts and resolidifies.
Wrought Foil 45.1174
A metal foil that is formed by the rolling of cast metal.
X
X Axis 26.1175
The horizontal or left-to-right direction in a two-
dimensional system of coordinates. (This axis is perpen-
dicular to the Y axis.)
Y
Y Axis 26.1303
The vertical or bottom-to-top direction in a two-
dimensional system of coordinates.
Z
Z Axis 26.1809
The Axis perpendicular to the plane formed by the X and
Y datum reference. This axis usually represents the thick-
ness of the boards.
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