IPC-SM-782A 表面安装设计和焊盘设计标准(带BGA).pdf - 第11页

IPC-782-1-1 Figure 1–1 Electrical assembly types PLCC CHIP COMPONENT SOIC DIP PLCC CHIP COMPONENT SOIC DIP PLCC CHIP COMPONENT SOIC PLCC 2-Sided Thru-hole (NOT RECOMMENDED) SO CHIP COMPONENT PLCC CHIP COMPONENT CHIP COMP…

6. High performance products consisting of ground-based

and shipbound military products, high speed and high

capacity computers, critical process controllers, and

life supporting medical systems. Quality, reliability

and performance are paramount, closely followed by

size and function. Cost is optimized based on these

requirements but is less important.

7. Space products include all of the products above which

are built to meet harsh outer space conditions. This

implies high quality and performance over a wide

range of environmental and physical extremes.

8. Military avionics products built to meet demanding

mechanical and thermal changes. Size, weight, perfor-

mance and reliability are paramount.

9. Under the hood automotive electronics products

endure the harshest of all use environments. These

products face extreme temperatures and mechanical

variations. Adding to this is the pressure of achieving

the lowest cost and optimum manufacturability in high

volumes.

1.2.2 Producibility Levels

When appropriate this stan-

dard will provide three design complexity levels of fea-

tures, tolerances, measurements, assembly, testing of

completion or veriﬁcation of the manufacturing process

that reﬂect progressive increases in sophistication of tool-

ing, materials or processing and, therefore progressive

increases in fabrication cost. These levels are:

Level A General Design Complexity—Preferred

Level B Moderate Design Complexity—Standard

Level C High Design Complexity—Reduced Produc-

ibility

Producibility levels also pertain to the assembly. The three

component mounting complexity levels which reﬂect pro-

gressive increases in sophistication of tooling, assembly

and joining techniques and therefore progressive increases

in cost are:

Level A simple assembly techniques used to describe

through the board component mounting;

Level B moderate assembly techniques used to

describe surface component mounting and

Level C complex assembly techniques used to

describe intermixing of through-the-board

and surface mounting on the same assembly.

Classiﬁcation of complexity should not be confused with

the performance classiﬁcation of end-item use described in

paragraph 1.2.

1.3 Assembly Types A type designation signiﬁes further

sophistication describing whether components are mounted

on one or both sides of the packaging and interconnecting

structure. Type 1 deﬁnes an assembly that has components

mounted on only one side; type 2 is an assembly with

components on both sides. Type 2 is limited to only class

B or C assemblies.

Figure 1–1 shows the relationship of two types of assem-

blies.

The need to apply certain design concepts should depend

on the complexity and precision required to produce a par-

ticular land pattern or P&I structure. Any design class may

be applied to any of the end-product equipment categories;

therefore, a moderate complexity (Type 1B) would deﬁne

components mounted on one side (all surface mounted) and

when used in a Class 2 product (dedicated service electron-

ics) is referred to as Type 1B, Class 2. The product

described as a Type 1B, Class 2 might be used in any of the

end-use applications; the selection of class being dependent

on the requirements of the customers using the application.

1.4 Presentation

Dimensions and tolerances are

expressed in millimeters (mm) or microns (mn) as appro-

priate. When no unit of measurement is shown, the unit

shall be assumed to be ‘‘mm.’’ Reference information for

inch conversion is shown in the appendix.

1.5 Profile Tolerances

Proﬁle tolerances are used in the

dimensioning system for determining the relationship

between component outlines and land pattern geometries.

The details are described in Section 3.3, and follow the

principles set forth in ANSI Y14.5. All dimensions are con-

sidered maximum or minimum material condition (depend-

ing on the features being analyzed), thus the proﬁle toler-

ances are unilateral (one-direction—maximum to

minimum, or minimum to maximum) as opposed to bilat-

eral (plus or minus) from a nominal characteristic.

1.6 Land Pattern Determination

This document dis-

cusses two methods of providing information on land pat-

terns:

(1) exact details based on industry component speciﬁca-

tions, board manufacturing and component placement

accuracy capabilities. These land patterns are regis-

tered to a speciﬁc component, and have a registered

land pattern number, see Table 3.5 and paragraph

3.3.3.4.

(2) equations that can be used to alter the given informa-

tion to achieve a more robust solder connection, when

used in particular situations where the equipment for

placement or attachment are more or less precise than

the assumptions made when determining the exact land

pattern details.

1.6.1 General Usage of SMT In general, a product is a

good candidate for SMT if it needs to be:

IPC-SM-782A December 1999

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IPC-782-1-1

Figure 1–1 Electrical assembly types

PLCC

CHIP COMPONENT

SOIC

DIP

PLCC

CHIP

COMPONENT

SOIC

DIP

PLCC

CHIP COMPONENT

SOIC

PLCC

2-Sided Thru-hole (NOT RECOMMENDED)

CHIP

COMPONENT

PLCC

CHIP

COMPONENT

CHIP

COMPONENT

SOIC

CHIP

COMPONENT

SOIC

DIP

SOLDER

PASTE

SOLDER

PASTE

SOIC

Through-hole

Simple

SMT

Simple

SMT/TH

Complex

Type 1

Type 2

SMT

Complex

TH/SMT

Simple

SMT/TH

FPT/CMT

Complex

SOLDER

PASTE

Adhesive (Optional)

FPT

Simple

Wire bond or

tab IC chip

attachment

FPT PKG.

(selectively attached)

December 1999 IPC-SM-782A

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• Small in size, real estate constrained

• Able to accommodate large amounts of memory

• Light in weight

• Able to accommodate several large, high lead count com-

plex ICs, such as ASICs and silicon arrays

• Able to function at high frequencies and speeds

• Able to transmit little or no noise, EMI and RFI resistant

• Able to be built in large volumes using automation

Currently, most SMT boards that have 50 or more compo-

nents use a combination of SMT and through-hole tech-

nologies. The mix is a function of component availability,

multiplicity of vendors, and cost. A mix of 80 percent SMT

and 20 percent through-hole parts is very common. How-

ever, the number of 100% SMT assemblies is increasing.

Fine Pitch Technology (FPT) involves a process change as

well as a packaging family, because the package to board

assembly steps are different than SMT. For example, sev-

eral commercially available FPT parts require lead excise

and forming prior to placement. They are encapsulated or

molded with plastic and delivered to users as a separate

packaged device, and these parts may be shipped with a

molded guard-ring or a slide carrier securing the leads in

place. The full encapsulated device will be used for direct

board mounting.

FPT packages are available under package names such as

PQFP (Plastic Quad Flat Pack), CQFP (Ceramic Quad Flat

Pack), QFP (Quad Flat Pack) and VSOIC (Very Small Out-

line Integrated Circuits).

2.0 APPLICABLE DOCUMENTS

The following documents, of the issue currently in effect

form a part of this document to the extend speciﬁed herein.

Other documents listed are for reference purposes to assist

the user.

2.1 IPC

IPC-A-48 Surface Mount Land Pattern Artwork (Mantech)

IPC-A-49

Surface Mount Land Pattern Artwork (IPC-SM-

782A)

IPC-T-50 Terms and Deﬁnitions

IPC-SC-60

Post Solder Solvent Cleaning Handbook

IPC-AC-62

Post Solder Aqueous Cleaning Handbook

IPC-2221

Generic Standard on Printed Board Design

IPC-6012

Qualiﬁcation and Performance Standard for

Rigid Printed Boards

IPC-D-330

Printed Wiring Design Guide

IPC-A-610

Acceptability of Printed Board Assemblies

IPC-7711

Rework of Electronic Assemblies

IPC-SM-780

Guidelines for Component Packaging and

Interconnection with Emphasis on Surface Mounting

IPC-SM-784

Guidelines for Chip-on-Board Technology

Implementation

IPC-SM-785

Guidelines for Accelerated Reliability Testing

of Surface Mount Solder Attachments

IPC-SM-786

Recommended Procedures for Handling of

Moisture Sensitive Plastic IC Packages

IPC-AJ-820

Assembly and Joining Handbook

IPC-CC-830

Electrical Insulating Compounds for Printed

Board Assemblies

IPC-SM-840

Qualiﬁcation and Performance of Permanent

Polymer Coating (Solder Mask) for Printed Boards

IPC-1902/IEC 60097

Grid System for Printed Circuits

2.2 Electronic Industries Association

IS-30

Surface Mount Resistors

JEDEC-95

JEDEC Registered and Standard Outlines for

Solid State Products

EIA-PDP-100

Registered and Standard Mechanical Out-

lines for Electronic Parts

RS-198

Ceramic Dielectric Capacitors

RS-228

Fixed Electrolytic Tantalum Capacitors

RS-367

Dimensional and Electrical Characteristics Deﬁn-

ing Receiver Type Sockets

RS-376

Fixed Film Dielectric Capacitors in Metallic and

Non- Metallic Cases for D.C. Application

RS-415

Dimensional and Electrical Characteristic Deﬁn-

ing Dual-In-Line-Type Sockets

RS-428

Type Designation System for Microelectronic

Devices

1. IPC, 2215 Sanders Road, Northbrook, IL 60062-6135

2. Electronic Industries Association, 2001 Eye Street N.W., Washington, DC 20006

IPC-SM-782A December 1999

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