IPC-CM-770D-1996 - 第15页

IPC-CM-770

Januaty

1996

26.0

26.1

26.2

26.3

26.4

27.0

27.1

27.2

27.3

27.4

27.5

28.0

28.1

28.2

28.3

28.4

29.0

29.1

29.2

29.3

29.4

29.5

30.0

30.1

30.2

30.3

30.4

30.5

30.6

Table

of

Contents

.

Section

6

Figures

HANDLING AND STORAGE

.................................

6-1

General Considerations

.................................

6-1

Figure 26-1 Warning Symbols

.......................................................

6-2

Electrostatic Discharge @SD) Protection

....

6-1

Figure 26-3 Schematic of a Typical Grounded Work Station

......

6-4

Handling

........................................................

6-

1

Figure 26-4 Features of a Grounded Work Station

......................

6-4

Storage

..........................................................

6-3

Figure 26-5 Installation Guidelines for Grounded Work

Automation and Equipment

.........................

6-4

Benches and Floor Mats

............................................

6-5

......................................

SOLDER-RELATED CONSIDERATIONS

6-7

Figure 26-6 Proper Handling Procedures 6-6

Figure 30-2 R&R System Having a Very High Degree of

..............

General Considerations 6-7

.................................

Airkas Flow Control

...............................................

6-28

.

Solderability

..................................................

6-8

Materials

.......................................................

6-9

Component R&R System

........................................

6-29

Figure 30-3 Commercially Available Surface Mount

Component Retention

.................................

6-12

Figure 30-4 Single-sided Hot Air Component Remover

............

6-29

Machine Soldering Processes

.....................

6-12

Figure 30-5 Double-sided Hot Component Remover

.................

6-29

............

CLEANING-RELATED CONSIDERATIONS

6-18

Figure 30-6 Commercial Hot Air Component Remover 6-29

........

~~

Figure 30-7 Small Hot Air Jet Lap Solder Joint Component

General Considerations

...............................

6-18

Removal

...................................................................

6-30

Pre-Cleaning

...............................................

6-18

Post-Soldering Cleaning

.............................

6-18

Component Removal

...............................................

6-30

Figure 30-8 Lap Reflow Soldering Tool Used for

Quality Assurance

.......................................

6-18

Figure 30-9 Hot Gripper

.

Hand Force Component

Remover

...................................................................

6-30

CONFORMAL COATING-RELATED

CONSIDERATIONS

..............................................

6-19

Figure 30-10 Thermal Tweezer -Finger Tip Controlled

Comoonent Remover

...............................................

6-30

General Considerations

...............................

6-19

Materials

.....................................................

6-19

Caution Notes 6-20

Tables

............................................

coating Techniques

....................................

6-21

Table 26-1 Susceptibility Ranges of Various Devices Exposed to

Quality Assurance 6-21

Electrostatic Discharge from a Person or Electronic

Equivalent

.....................................................................

6-1

.......................................

QUALITY ASSURANCE TESTING

......................

6-22

Table 26-2 Maximum Allowable Resistances and Discharge

.................................

Preassembly Assurance 6-23

Times for Static Safe Operations 6-3

Solderability 6-23

Table 27-1 Solder Alloys 6-10

Quality Assurance Provisions 6-23

Table 27-2 Solder Bath Contamination Limits 6-11

General

...

6-24

Table 29-1 Coating Thickness

......................................................

6-20

Printed Board Structure Modification/

Repair

.........................................................

6-25

Printed Board Assembly Modification/

Appendix A

Repair Methods

...........................................

6-25

Metric Conversion Tables

............................................................

6-32

...............................

..............................................................

................................................

............................

.....................

X

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

January

1996

IPC-CM-770

Part One

General Information

1

.O

INTRODUCTION

When the manufacture of an interconnected electronic

package is viewed as the assembly, soldering, testing,

repair and rework of printed wiring assemblies the major

cost element is generally the actual component mounting

operation. This activity, critically important to subsequent

operations, as well as performance and reliability of higher

level assemblies, is the subject of the following document

which updates and adds to the information found in the

previous revision published in

1980.

1.1 Scope

This document provides guidelines for the

preparation of components for assembly to printed wiring

boards, and contains a review of some pertinent design cri-

teria, impacts and issues, techniques for assembly (both

manual and machines) as well as consideration of, and

impacts upon, subsequent soldering, cleaning, and coating

processes. The information herein consists of compiled

data representing commercial, industrial, and military

applications.

This “Guideline” has been organized in a manner which is

intended to simplify finding information relating to specific

component types in the earlier sections and general process

information in the later sections of the document. However,

because of the rapid progress and evolution in packaging

and assembly technology, all currently available compo-

nents or assembly techniques may not be covered in this

document.

1.2 Purpose

The purpose of this “Guideline” is to illus-

trate and guide the user seeking answers to questions

related to accepted, effective methods of mounting compo-

nents to printed wiring boards.

1.3 Producibility Levels

IPC documents reflect three

design complexity levels of features, tolerances, measure-

ments, assembly, testing of completion or verification of

the manufacturing process that reflect progressive increases

in sophistication of tooling, 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 Producibility

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 the 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

below.

1.3.1 Performance Classifications

Three general end-

product classes have been established in associated IPC

standards and specifications to reflect progressive increases

in sophistication, functional performance requirements and

tesdinspection frequency. It should be recognized that there

may be an overlap of equipment between classes.

Design requirements determine class. Class definitions are

useful for identifying degrees of precision needed to meet

desigdperformance requirements of packaging and inter-

connecting structures, and establish communication media

between design and manufacture and disciplines.

The printed board user has the responsibility to determine

the class to which his product belongs. The contract shall

specify the performance class required and indicate any

exceptions to specific parameters, where appropriate. In the

event of conflict between the design requirements and the

classes defined herein, the former shall take precedence

and be reflected in the master drawing.

These classes are:

CLASS 1 General Electronic Products

Includes consumer products, some computer and computer

peripherals, as well as general military hardware suitable

for applications where cosmetic imperfections are not

important and the major requirement is function of the

completed printed board or printed board assembly.

CLASS 2 Dedicated Service Electronic Products

Includes communications equipment, sophisticated busi-

ness machines, instruments and military equipment where

high performance and extended life is required, and for

1-1

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

IPC-CM-770

Januaty

1996

which uninterrupted service is desired but is not critical.

Certain cosmetic imperfections are allowed.

CLASS 3 High Reliability Electronic Products

Includes the equipment for commercial and military prod-

ucts where continued performance or performance on

demand is critical. Equipment downtime cannot be toler-

ated, and functionality is required for such applications as

life support items, or missile systems. Printed boards and

printed board assemblies in this class are suitable for appli-

cations where high levels of assurance are required and

service is essential.

The land patterns in this standard have the capability of

accommodating all three performance classifications.

1.4 ASSEMBLY TYPES

A type designation signifies fur-

ther sophistication describing whether components are

mounted on one or both sides of the packaging and inter-

connecting structure. Type

1

defines an assembly that has

components mounted on only one side; type

2

is an assem-

bly 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 printed board 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 electronics) is referred to as type lB, Class

2.

The

product described as Type lB, 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.

1.5 Presentation

All dimensions and tolerances are

expressed in metric. Reference information is shown in

parentheses

(

).

2.0 REFERENCE DOCUMENTS

The following documents, of the issue currently in effect

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

Other documents listed are for reference purposes to assist

the user.

2.1 Institute for Interconnecting and Packaging Elec-

tronic Circuits (IPC)’

IPC-T-50

Terms and Definitions

IPC-SCIO

Post Solder Solvent Cleaning Handbook

IPC-AC-62

Post Solder Aqueous Cleaning Handbook

IPC-RF-245

Performance Specification for Rigid-Flex

Printed Boards

IPC-D-249

Design Standard for Flexible Single- and

Double-Sided Printed Boards

IPC-FC-250

Performance Specification for Single- and

Double-Sided Flexible Printed Wiring

IPC-D-275

Design Standard for Rigid Printed Boards and

Rigid Printed Board Assemblies

IPC-RB-276

Qualification and Performance Specification

for Rigid Printed Boards

IPC-D-322

Guidelines for Selecting Printed Wiring Board

Sizes Using Standard Panel Sizes

IPC-MC-324

Qualification and Performance Specification

for Metal Core Boards

IPC-D-325

Documentation Requirements for Printed

Boards, Assemblies, and Support Drawings

IPC-D-330

Design Guide

IPC-PD-335

Electronic Packaging Handbook

IPC-C-406

Design and Application Guidelines for Surface

Mount Connectors

IPC-A-600

Acceptability of Printed Boards

IPC-A-61

O

Acceptability of Electronic Assemblies

IPC-R-700

Suggested Guidelines for Modification,

Rework, and Repair of Printed Wiring Boards and Assem-

blies

IPC-SM-782

Surface Mount Design and Land Pattern

Standard

IPC-SM-784

Guidelines for Chip-On-Board Technology

Implementation

IPC-AJ-820

Assembly and Joining Handbook

IPC-CA-821

General Requirements for Thermally Con-

ductive Adhesives

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-H-855

Hybrid Microcircuit Design Guide

SMC-TR-001

An Introduction to Tape Automated Bonding

Find Pitch Technology

l.

Institute for Interconnecting and Packaging Electronic Circuits,

2215

Sanders Road, Northbrook,

IL

60062.

1-2

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services