IPC-T-50F_.pdf.pdf - 第44页

Light Mark (Fabric) 44.0708 A ﬁlling defect that extends across the width of a fabric containing less than one pick per 25mm from nominal. Limits of Size 20.0709 The speciﬁed maximum and minimum sizes. Line 20.0710 see ‘…

Lead 36.0688

A length of insulated or uninsulated metallic conductor that

is used for electrical interconnections.

Lead Extension 75.0691

That part of a lead or wire that extends beyond a solder

connection.

Lead Frame 74.0692

The metallic portion of a component package that is used

to interconnect with semiconductor die by wire bonding

and to provide output terminal leads.

Lead Mounting Hole 22.0695

see ‘‘Component Hole.’’

Lead Pin 36.0696

see ‘‘Component Pin.’’

Lead Projection 73.0697

The distance that a component lead protrudes through the

side of a printed board that is opposite from the one upon

which the component is mounted.

Lead Wire 36.0698

see ‘‘Component Lead.’’

Leaded Chip Carrier 31.1224

A chip carrier whose external connections consist of leads

that are around and down the side of the package. (See also

‘‘Leadless Chip Carrier.’’)

Leaded Surface-Mount Component 33.1435

A surface-mount component for which external connec-

tions consist of leads that are around and down the side of

the package. (See Figure L-3.) (See also ‘‘Leadless

Surface-Mount Component.’’)

Leadless Chip Carrier 33.1436

A chip carrier whose external connections consist of met-

allized terminations that are integral part of the component

body. (See also ‘‘Leaded Chip Carrier.’’)

Leadless Component 30.1754

see Leadless Surface Mount Components .

Leadless Device 33.0694

see Die and Leadless Surface Mount Component .

Leadless Inverted Device 33.1437

A shaped metallized-ceramic form used as an intermediate

carrier for diode or transistor die that has been especially

adapted for leadless surface mounting.

Leadless Surface-Mount Component 33.1438

A surface-mount component whose external connections

consist of metallized terminations that are integral part of

the component body. (See also ‘‘Leaded Surface-Mount

Component.’’)

Leakage Current 21.0699

The undesired ﬂow of electrical current over or through an

insulator.

Learn Time 92.0700

The time it takes to do initial programming (teaching) to

store feature coordinate locations and other data in an

inspection/test machines memory.

Least Material Condition (LMC) 22.0701

The condition in which a feature of size contains the least

amount of material within the stated limits of size.

Legend 22.1439

A format of letters, numbers, symbols and patterns that are

used primarily to identify component locations and orien-

tations for convenience of assembly and maintenance

operations.

Leno End Out 44.0702

Warp-end wrapper that is missing from the end of a fabric.

Levelling 56.0703

see ‘‘Fusing.’’

Levelling Flux 56.0704

see ‘‘Fusing Flux.’’

Levelling Oil 56.0705

see ‘‘Fusing Oil.’’

Library 20.0706

A catalog of related items that contains all of the informa-

tion about the items that is necessary for processing by a

computer program.

Lifted Land 60.0707

A land that has fully or partially separated (lifted) from the

base material, whether or not any resin is lifted with the

land.

IPC-I-001034

Figure L–3 Leaded surface mount component gull-wing

shaped lead

FOOT

HEEL

TOE

LAND

KNEE

UPPER

BEND RADIUS

LOWER

BEND RADIUS

June 1996 IPC-T-50F

Light Mark (Fabric) 44.0708

A ﬁlling defect that extends across the width of a fabric

containing less than one pick per 25mm from nominal.

Limits of Size 20.0709

The speciﬁed maximum and minimum sizes.

Line 20.0710

see ‘‘Conductor.’’

Line Coupling 21.0711

The interaction between two transmission lines that is

caused by their mutual inductance and the capacitance

between them.

Lip Height 51.0712

The perpendicular distance from one primary cutting edge

to another.

Load Capacitance 21.0713

The capacitance seen by the output of a logic circuit or

other signal source.

Load Time 92.0714

The time it takes to load a unit in an inspection/test

machine and to perform any necessary programming or

machine alignment.

Local Fiducial 20.0715

A ﬁducial mark (or marks) used to locate the position of a

land pattern for an individual component on a printed

board.

Local Intelligence 25.0716

The capability of a work station to independently process

data without the use of a host or central processing unit.

Locating Edge 20.0028

A tooling feature in the form of the edge of a printed board.

Locating Edge Marker 20.0717

A symbol that is used to identify which edge of a printed

board is the index edge.

Locating Hole 20.0718

see ‘‘Tooling Hole.’’

Locating Notch 20.0719

A tooling feature in the form of a notch in a printed board.

Locating Slot 20.0720

A tooling feature in the form of a slot in a printed board.

Location Hole 20.1726

A hole or notch in the panel or printed board to enable

either to be positioned accurately.

Logic 21.0721

The functional digital circuits used to perform computa-

tional functions.

Logic Diagram 21.1440

A drawing that depicts the multistate device implementa-

tion of logic functions with logic symbols and supplemen-

tary notations that show the details of signal ﬂow and con-

trol, but not necessarily the point-to- point wiring.

Logic Family 21.1441

A collection of logic functions using the same form of

electronic circuit, e.g., emitter-coupled logic (ECL),

transistor-transistor logic (TTL), complementary metal-

oxide semiconductor logic (CMOS).

Long-Term Capability 91.0722

The capability of a process that exhibits statistical control

over an extended period of time.

Loom Beam 44.0723

A large ﬂanged cylinder onto which all warp yarns are

wound and from which the yarns enter the loom.

Loop Height 76.0725

The magnitude of deviation of a wire from a straight path

between its end attachment points.

Loop, Wire 76.0724

The curve (arc) in a bonding wire between its end attach-

ment points.

Loss Tangent 21.0726

see ‘‘Dissipation Factor.’’

Lot Size 91.1442

A collection of units produced in one continuous, uninter-

rupted fabrication run from which a sample is drawn and

inspected or tested in order to determine conformance with

acceptability criteria.

Luminance 24.0727

A measure of light ﬂux reﬂected or emitted from a surface.

Luminous Energy 24.0728

A measure of light ﬂux ﬂow rate, usually in units of lumen-

seconds.

Luminous Flux 24.0729

A measure of ﬂow of visible light energy past any given

point in space.

Lyophilic 76.1225

A characterization of material that readily goes into colloi-

dal suspension in a liquid.

IPC-T-50F June 1996

Lyophobic 76.0730

A characterization of material that exists in a colloidal state

with a tendency to repel liquids.

Machine Language 11.0732

The actual language, usually a binary code, that is used by

a computer when it performs operations.

Machined Contact 37.0731

A type of connector contact that consists of solid spring

metal that has been formed by machining. (See also

‘‘Sheet-Metal Contact.’’)

Magnification Power 92.0733

The ratio of the tangent of one-half of the angle (beta) sub-

tended by the image of an object (H), as seen through and

centered in the ﬁeld of view of the magniﬁcation device, to

the tangent of one-half of the angle (alpha) subtended by

the object (H) as seen at 10 inches by the unaided eye. (See

Figure M-1.)

Major Defect 94.0734

A defect that is likely to result in a failure of a unit or

product or that materially reduces its usability for its

intended purpose.

Manhattan Distance 25.0735

The orthogonal distance between two points.

Manual Data Input 25.0736

Computer data that is manually generated with or without

the aid of a data-entry device, such as a keyboard, lightpen,

mouse, etc.

Manual Soldering 75.0737

see ‘‘Hand Soldering.’’

Manufacturing Drawing 26.1634

A working document that shows the dimensional limits or

grid locations that are applicable to any and all parts of a

product to be fabricated, including the arrangement of con-

ductors and nonconductive patterns or elements; the size,

type, and location of holes; and all other necessary infor-

mation.

Manufacturing Hole 20.0738

see ‘‘Tooling Hole.’’

Margin (Flat Cable) 37.0739

The distance between the reference edge of a ﬂat cable and

the nearest edge of the ﬁrst conductor. (See also ‘‘Edge

Spacing.’’)

Margin Width (Drill) 51.0740

The thickness of the cylindrical portion of a drill land that

is perpendicular to the leading edge.

IPC-I-002273

Figure M–1 Magniﬁcation power parameters

▼

Magnifying aid focused so eye is 

focused for infinity

Centered Image

of the Object

seen through aid

’

1/2 H

’

▼

254mm [10"]

Object viewed

with unaided

eye

1/2 H

▼

▼▼

June 1996 IPC-T-50F