IPC-T-50F_.pdf.pdf - 第76页

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 suf f iciently high to melt the solder being use…

Twist 60.1553

The deformation of a rectangular sheet, panel or printed

board, that occurs parallel to a diagonal across its surface,

such that one of the corners of the sheet is not in the plane

that contains the other three corners.

Two-Layer Carrier Tape 36.1554

The carrier for conductors used in tape-automated bonding

that consists of a dielectric layer with a layer of plated/

etched conductors. (See also ‘‘Multilayer Carrier Tape,’’

‘‘Single-Layer Carrier Tape,’’ and ‘‘Three-Layer Carrier

Tape.’’)

Two-Piece Contact 37.1115

A type of discrete connector contact that mates with

another discrete formed-metal connector contact. (See also

‘‘Edge-Board Contact.’’)

Two-Sided Board 60.1116

see ‘‘Double-Sided Board.’’

Type I Error 91.1117

The rejection of a hypothesis that is true.

Type II Error 94.1118

The accepting of a hypothesis that is false.

Ultrasonic Bonding 74.1119

A termination process that uses ultrasonic-frequency vibra-

tion energy and pressure to make the joint.

Ultrasonic Cleaning 76.1120

Immersion cleaning that is done by passing high-frequency

sound waves through a cleaning medium to cause micro-

agitation.

Ultrasonic Soldering 75.1121

Fluxless soldering wherein molten solder is vibrated at

ultrasonic frequencies while making the joint.

Unbalanced Transmission Line 21.1556

A transmission line that has distributed inductance, capaci-

tance, resistance, and conductance elements that are not

equally distributed between its conductors.

Uncased Device 35.1122

A component without a package.

Unconditional Test 92.1123

A test without limitations or restrictions on test mode, test

time, etc.

Undercut, After Fabrication 92.1124

The distance, measured parallel to the surface of a printed

board, from the outer edge of a conductor (excluding over-

plating and coatings) to the maximum point of the indenta-

tion on the same edge of

Undercut, In Process 92.1125

The distance, measured parallel to the surface of a printed

board, from the outer edge of a conductor (including etch

resist) to the maximum point of the indentation on the

same edge of the conductor. (See also ‘‘Undercut, After

Fabrication.’’)

Underwriters Symbol 94.1126

A logotype that denotes that a product has been recognized

(accepted) by Underwriters Laboratories, Inc. (UL).

Unfil 44.1127

A device attached to the loom which automatically winds

yarn onto quills from yarn packages and maintains a sup-

ply of quills for the shuttle.

Unload Time 92.1128

The time required to remove a unit from the evaluation

equipment, to collect the evaluation data, and to make the

system ready for the next unit.

Unsupported Hole 22.1129

A hole in a printed board that does not contain plating or

other type of conductive reinforcement.

Upload (Test) 92.1130

The ability of an analyzer to accept test program data from

a host computer.

Usable Resolution 52.1131

The smallest image and separation that can be produced,

and subsequently processed, in a given emulsion or thick-

ness of photoresist.

User Inspection Lot (Material) 91.1132

All of the material of the same type and, as far as practical,

of the same type designation that is produced from the

same equivalent batches or lots of constituent material

under essentially the same conditions and that is offered for

inspection at one time.

Vacuum Evaporation 53.1133

The deposition of a metal ﬁlm onto a base material by

evaporation techniques.

Vacuum Head 73.1775

A handling instrument with a small vacuum cup which is

used to pick up clip devices and other surface mounting

devices.

June 1996 IPC-T-50F

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.

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

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