IPC-SM-782A 表面安装设计和焊盘设计标准(带BGA).pdf - 第17页

IPC-782-3-1 Figure 3–1 Examples of typical package styles and package descriptive designators Examples Package Outline Style and Code CC Chip Carrier PQCC PQCC (PLCC) PQCC (CLCC) PQCC (CLCC) CY Cylinder DB Disk Button MB…

a. All dimensions are basic (nominal)

b. Limits of size control form as well as size.

c. Perfect form is required at maximum dimensions.

d. Datum references and position tolerances apply at maxi-

mum dimensions, and are dependent on feature size.

e. Position dimensions originate from maximum dimen-

sions.

f. Tolerances and their datum references other than size

and position apply regardless of feature size (RFS).

g. Interpretations are per ANSI Y14.5.

The dimensioning concepts used for this system of analy-

sis consider the assembly/attachment requirements as their

major goal. Speciﬁcation (data) sheets for components or

dimensions for land patterns on boards may use different

dimensioning concepts, however, the goal is to combine all

concepts into a single system. Users are encouraged to

establish the appropriate relationship between their dimen-

sioning system(s) and the proﬁle dimensioning system and

analysis concepts described herein to allow for ease of tai-

loring these concepts for robust process performance. As

an example, if the tolerance used for positioning is larger

than the machine tolerance used in production, a single

dimensional change in a ‘‘spread sheet’’ program could

modify the land pattern dimensions shown in sections 8.0

through 13.0 in order to optimize the process for a given

facility.

3.3.1 Component Tolerancing

The component manu-

facturers and the Electronic Industries Association (EIA)

are responsible for the dimensioning and tolerancing of

electronic components. Their concepts have been converted

to a functional equivalent using the proﬁle tolerancing

method with all components shown with their basic dimen-

sions as limit dimensions (maximum or minimum size).

Table 3–1 Terminal Position Preﬁxes

Code Name Position (see notes 1 and 2)

A Axial Terminal extend from both ends in the direction of the major axis of a cylindrical or elliptical

package.

B Bottom Terminals beneath the seating plan of the package.

D Dual Terminals on opposite sides of a square or rectangular package or located in two parallel rows.

E End Terminals are package endcaps having circular or elliptical cross section.

L Lateral Terminals are on the four sides of a square or rectangular package. The preferred name is

‘‘Quad,’’ code Q.

P Perpendicular Pins are perpendicular to seating plan on a square or rectangular package. Restrict to PGA

family.

Q Quad Terminals are on the four sides of a square or rectangular package or located in four parallel

rows.

R Radial Terminals extend radially from the periphery of a cylindrical or spherical package

S Single Terminals are on one surface of a square or rectangular package in a single row.

T Triple Terminals are on three sides of a square or rectangular package.

U Upper Terminals are perpendicular to and opposite the seating plane, and are on one surface of a

package.

X Other Terminal positions other than those described.

Z Zig-zag Terminals are on one surface of a square or rectangular package arranged in a staggered

conﬁguration. Restrict to ZIP family.

NOTE 1: These descriptions assume the seating plane is the bottom of the package.

NOTE 2: Reference to package shape does not take into account ﬂanges, notches, or irregularities.

Table 3–2 Package-Outline-Style Codes

Code Outline Style

CC Chip-carrier package

CY Cylinder or can package

DB Disc-button package

FM Flange-mount package

FO Fiber-optic-device package

FP Flatpack package

GA Grid-array package

IL In-line package. The preferred designator is IP

IP In-line package or inserted package. Restrict to

DIP/SIP/ZIP.

LF Long-form horizontal package.

MA Microelectronic assembly.

MW Microwave package

PF Press-ﬁt package

PM Post-/stud-mount package

SO Small-outline package

SS Special-shape package

UC Uncased chip

XA-XZ Nondeﬁend family; vendor or user option.

IPC-SM-782A December 1999

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IPC-782-3-1

Figure 3–1 Examples of typical package styles and package descriptive designators

Examples

Package

Outline

Style

and Code

Chip Carrier

PQCC PQCC

(PLCC)

PQCC

(CLCC)

PQCC

(CLCC)

Cylinder

Disk Button

MBCY MBCY

CQFP

LRDB GRDB PRDB

PBCY

Press Fit

Post/Stud

Mount

Small

Outline

Special

Shape

MUPF

MUPM MUPM CRPM

PDSS

PDSO PDSO PSSO

Flatpack

PADB

CDFP PQFP

December 1999 IPC-SM-782A

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Proﬁle tolerances are unilateral, and are described to reﬂect

the best condition for solder joint formation usually at

minimum component size. As the proﬁle tolerance moves

in this unilateral direction toward maximum component

size, the opportunity for a robust solder joint decreases.

The concept for component dimension evaluations is based

on evaluating the surfaces of the component termination

and component lead that are involved in the formation of

the acceptable solder joint. Component manufacturers usu-

ally provide dimensions for their parts with a nominal size

and then put a tolerance on that nominal dimension. Inor-

der to facilitate the dimensioning system, these dimensions

and their associated tolerances are converted to minimum

and maximum size.

As an example, capacitor C1206 has a manufactured nomi-

nal dimension for its length (L) of 3.2 mm. The tolerance

described by the manufacturer is

0.2 mm. Thus, the mini-

mum dimension of ‘‘L’’ is 3.0 mm with a unilateral toler-

ance of 0.4 mm, resulting in its maximum dimension being

3.4 mm.

Figure 3–4 shows the characteristics for the C1206. Figure

3–4a shows the component manufacturers dimensions for

IPC-782-3-2

Figure 3–2 Lead-form (or terminal-shape) examples

BUTT "C" BEND

SOLDER LUG FLAT

GULL WING HIGH-CURRENT CABLE

"J" BEND NO LEAD

PIN/PEG WRAPAROUND

"S" BEND THROUGH-HOLE

"J" INVERTED WIRE

BODY OF PACKAGE LAND STRUCTURE

IPC-SM-782A December 1999

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