Printed Circuits Handbook

Printed Circuits Handbook

Authors: Clyde Coombs

Published: August 2007

eISBN: 9780071510790 0071510796 | ISBN: 9780071467346

Contents

List of Contributors

Preface

Part 1 Lead-Free Legislation

Chapter 1. Legislation and Impact on Printed Circuits

1.1 Legislation Overview

1.2 Waste Electrical and Electronic Equipment (WEEE)

1.3 Restriction of Hazardous Substances (RoHS)

1.4 RoHS’ Impact on the Printed Circuit Industry

1.5 Lead-Free perspecives

1.6 Other Legislative Initiatives

Part 2 Printed Circuit Technology Drivers

Chapter 2. Electronic Packaging and High-Density Interconnectivity

2.1 Introduction

2.2 Measuring the Interconnectivity Revolution (HDI)

2.3 Hierarchy of Interconnections

2.4 Factors Affecting Selection of Interconnections

2.5 ICS and Packages

2.6 Density Evaluations

2.7 Methods to Increase PWB Density

References

Chapter 3. Semiconductor Packaging Technology

3.1 Introduction

3.2 Single-Chip Packaging

3.3 Multichip Packages

3.4 Optical Interconnects

3.5 High-Density/High-Performance Packaging Summary

3.6 Roadmap Information

References

Chapter 4. Advanced Component Packaging

4.1 Introduction

4.2 Lead-Free

4.3 System-on-a-Chip (SOC) versus System-on-a-Package (SOP)

4.4 Multichip Modules

4.5 Multichip Packaging

4.6 Enabling Technologies

4.7 Acknowledgment

References

Chapter 5. Types of Printed Wiring Boards

5.1 Introduction

5.2 Classification of Printed Wiring Boards

5.3 Organic and Nonorganic Substrates

5.4 Graphical and Discrete-Wire Boards

5.5 Rigid and Flexible Boards

5.6 Graphically Produced Boards

5.7 Molded Interconnection Devices

5.8 Plated-Through-Hole (PTH) Technologies

5.9 Summary

References

Part 3 Materials

Chapter 6. Introduction to Base Materials

6.1 Introduction

6.2 Grades and Specifications

6.3 Properties Used to Classify Base Materials

6.4 Types of FR-4

6.5 Laminate Identification Scheme

6.6 Prepreg Identification Scheme

6.7 Laminate and Prepreg Manufacturing Processes

References

Chapter 7. Base Material Components

7.1 Introduction

7.2 Epoxy Resin Systems

7.3 Other Resin Systems

7.4 Additives

7.5 Reinforcements

7.6 Conductive Materials

References

Chapter 8. Properties of Base Materials

8.1 Introduction

8.2 Thermal, Physical, and Mechanical Properties

8.3 Electrical Properties

References

Chapter 9. Base Materials Performance Issues

9.1 Introduction

9.2 Methods of Increasing Circuit Density

9.3 Copper foil

9.4 Laminate Constructions

9.5 Prepreg Options and Yield-Per-Ply Values

9.6 Dimensional Stability

9.7 High-Density Interconnect/Microvia Materials

9.8 CAF Growth

9.9 Electrical Performance

References

Chapter 10. The Impact of Lead-Free Assembly on Base Materials

10.1 Introduction

10.2 RoHS Basics

10.3 Base Material Compatibility Issues

10.4 The Impact of Lead-Free Assembly on Base Material Components

10.5 Critical Base Material Properties

10.6 Impact on Printed Circuit Reliability and Material Selection

10.7 Summary

References

Chapter 11. Selecting Base Materials for Lead-Free Assembly Applications

11.1 Introduction

11.2 Pcb fabrication and Assembly Interactions

11.3 Selecting the Right Base Material for Specific Application

11.4 Example Application of this Tool

11.5 Discussion of the Range of Peak Temperatures for Lead-Free Assembly

11.6 Lead-Free Applications and Ipc-4101 Specification Sheets

11.7 Additional Base material Options for Lead-Free Applications

11.8 Summary

References

Chapter 12. Laminate Qualification and Testing

12.1 Introduction

12.2 Industry Standards

12.3 Laminate Test Strategy

12.4 Initial Tests

12.5 Full Material Characterization

12.6 Characterization Test Plan

12.7 Manufacturability in the Shop

Part 4 Engineering and Design

Chapter 13. Physical Characteristics of the PCB

13.1 Classes of PCB Designs

13.2 Types of PCBs or Packages for Electronic Circuits

13.3 Methods of Attaching Components

13.4 Component Package Types

13.5 Materials Choices

13.6 Fabrication Methods

13.7 Choosing a Package Type and Fabrication Vendor

Chapter 14. The PCB Design Process

14.1 Objective of the PCB Design Process

14.2 Design Processes

14.3 Design Tools

14.4 Selecting a Set of Design Tools

14.5 Interfacing Cae, Cad, and CAM Tools to Each Other

14.6 Inputs to the Design Process

Chapter 15. Electrical and Mechanical Design Parameters

15.1 Printed Circuit Design Requirements

15.2 Introduction to Electrical Signal Integrity

15.3 Introduction to Electromagnetic Compatibility

15.4 Noise Budget

15.5 Designing for Signal Integrity and Electromagnetic Compatibility

15.6 Mechanical Design Requirements

References

Chapter 16. Current Carrying Capacity in Printed Circuits

16.1 Introduction

16.2 Conductor (Trace) Sizing Charts

16.3 Current Carrying Capacity

16.4 Charts

16.5 Baseline Charts

16.6 Odd-Shaped Geometries and the “Swiss Cheese” Effect

16.7 Copper Thickness

References

Chapter 17. PCB Design for Thermal Performance

17.1 Introduction

17.2 The PCB as a Heat Sink Soldered to the Component

17.3 Optimizing the PCB for Thermal Performance

17.4 Conducting Heat to the Chassis

17.5 PCB Requirements for High-Power Heat Sink Attach

17.6 Modeling the Thermal Performance of the PCB

References

Chapter 18. Information Formating and Exchange

18.1 Introduction to Data Exchange

18.2 The Data Exchange Process

18.3 Data Exchange Formats

18.4 Drivers for Evolution

18.5 Acknowledgment

References

Chapter 19. Planning for Design, Fabrication, and Assembly

19.1 Introduction

19.2 General Considerations

19.3 New Product Design

19.4 Layout Trade-off Planning

19.5 PWB Fabrication Trade-off Planning

19.6 Assembly Trade-Off Planning

References

Chapter 20. Manufacturing Information, Documentation, and Transfer Including CAM Tooling for Fab and Assembly

20.1 Introduction

20.2 Manufacturing Information

20.3 Initial Design Review

20.4 Design Input

20.5 Design Analysis and Review

20.6 The CAM-Tooling Process

20.7 Additional Processes

20.8 Acknowledgment

Chapter 21. Embedded Components

21.1 Introduction

21.2 Definitions and Example

21.3 Applications and Trade-Offs

21.4 Designing for Embedded Component Applications

21.5 Materials

21.6 Material Supply Types

Part 5 High Density Interconnection

Chapter 22. Introduction to High-Density Interconnection (HDI) Technology

22.1 Introduction

22.2 Definitions

22.3 HDI Structures

22.4 Design

22.5 Dielectric Materials and Coating Methods

22.6 HDI Manufacturing Processes

References

Bibliography-Additional Reading

Chapter 23. Advanced High-Density Interconnection (HDI) Technologies

23.1 Introduction

23.2 Definitions of HDI Process Factors

23.3 HDI Fabrication Processes

23.4 Next-Generation HDI Processes

References

Part 6 Fabrication

Chapter 24. Drilling Processes

24.1 Introduction

24.2 Materials

24.3 Machines

24.4 Methods

24.5 Hole Quality

24.6 Postdrilling Inspection

24.7 Drilling Cost Per Hole

Chapter 25. Precision Interconnect Drilling

25.1 Introduction

25.2 Factors Affecting High-Density Drilling

25.3 Laser versus Mechanical

25.4 Factors Affecting High-Density Drilling

25.5 Depth-Controlled Drilling Methods

25.6 High-Aspect-Ratio Drilling

25.7 Innerlayer Inspection of Multilayer Boards

Chapter 26. Imaging

26.1 Introduction

26.2 Photosensitive Materials

26.3 Dry-Film Resists

26.4 Liquid Photoresists

26.5 Electrophoretic Depositable Photoresists

26.6 Resist Processing

26.7 Design for Manufacturing

References

Chapter 27. Multilayer Materials and Processing

27.1 Introduction

27.2 Printed Wiring Board Materials

27.3 Multilayer Construction Types

27.4 ML-PWB Processing and Flows

27.5 Lamination Process

27.6 Lamination Process Control and Troubleshooting

27.7 Lamination Overview

27.8 ML-PWB Summary

References

Chapter 28. Preparing Boards for Plating

28.1 Introduction

28.2 Process Decisions

28.3 Process Feedwater

28.4 Multilayer PTH Preprocessing

28.5 Electroless Copper

28.6 Acknowledgment

References

Chapter 29. Electroplating

29.1 Introduction

29.2 Electroplating Basics

29.3 High-Aspect Ratio Hole and Microvia Plating

29.4 Horizontal Electroplating

29.5 Copper Electroplating General Issues

29.6 Acid Copper Sulfate Solutions and Operation

29.7 Solder (Tin-Lead) Electroplating

29.8 Tin Electroplating

29.9 Nickel Electroplating

29.10 Gold Electroplating

29.11 Platinum Metals

29.12 Silver Electroplating

29.13 Laboratory Process Control

29.14 Acknowledgment

References

Chapter 30. Direct Plating

30.1 Direct Metallization Technology

References

Chapter 31. PWB Manufacture Using Fully Electroless Copper

31.1 Fully Electroless Plating

31.2 The Additive Process and its Variations

31.3 Pattern-Plating Additive

31.4 Panel-Plate Additive

31.5 Partly Additive

31.6 Chemistry of Electroless Plating

31.7 Fully Electroless Plating Issues

References

Chapter 32. Printed Circuit Board Surface Finishes

32.1 Introduction

32.2 Alternative Finishes

32.3 Hot Air Solder Level (Hasl or Hal)

32.4 Electroless Nickel Immersion Gold (ENIG)

32.5 Organic Solderability Preservative (OSP)

32.6 Immersion Silver

32.7 Immersion Tin

32.8 Other Surface Finishes

32.9 Assembly Compatibility

32.10 Reliability Test Methods

32.11 Special Topics

32.12 Failure Modes

32.13 Comparing Surface Finish Properties

References

Chapter 33. Solder Mask

33.1 Introduction

33.2 Trends and Challenges for Solder Mask

33.3 Types of Solder Mask

33.4 Solder Mask Selection

33.5 Solder Mask Application and Processing

33.6 VIA Protection

33.7 Solder Mask Final Properties

33.8 Legend and Marking (Nomenclature)

Chapter 34. Etching Process and Technologies

34.1 Introduction

34.2 General Etching Considerations and Procedures

34.3 Resist Removal

34.4 Etching Solutions

34.5 Other Materials for Board Construction

34.6 Metals Other than Copper

34.7 Basics of Etched Line Formation

34.8 Equipment and Techniques

References

Chapter 35. Machining and Routing

35.1 Introduction

35.2 Punching Holes (Piercing)

35.3 Blanking, Shearing, and Cutting of Copper-Clad Laminates

35.4 Routing

35.5 Scoring

35.6 Acknowledgment

Part 7 Bare Board Test

Chapter 36. Bare Board Test Objectives and Definitions

36.1 Introduction

36.2 The Impact of HDI

36.3 Why Test?

36.4 Circuit Board Faults

Chapter 37. Bare Board Test Methods

37.1 Introduction

37.2 Nonelectrical Testing Methods

37.3 Basic Electrical Testing Methods

37.4 Specialized Electrical Testing Methods

37.5 Data and Fixture Preparation

37.6 Combined Testing Methods

Chapter 38. Bare Board Test Equipment

38.1 Introduction

38.2 System Alternatives

38.3 Universal Grid Systems

38.4 Flying-Probe/Moving-Probe Test Systems

38.5 Verification and Repair

38.6 Test Department Planning and Management

Chapter 39. HDI Bare Board Special Testing Methods

39.1 Introduction

39.2 Fine-Pitch Tilt-Pin Fixtures

39.3 Bending Beam Fixtures

39.4 Flying Probe

39.5 Coupled Plate

39.6 Shorting Plate

39.7 Conductive Rubber Fixtures

39.8 Optical Inspection

39.9 Noncontact Test Methods

39.10 Combinational Test Methods

Part 8 Assembly

Chapter 40. Assembly Processes

40.1 Introduction

40.2 Through-Hole Technology

40.3 Surface-Mount Technology

40.4 Odd-Form Component Assembly

40.5 Process Control

40.6 Process Equipment Selection

40.7 Repair and Rework

40.8 Conformal Coating, Encapsulation, and Underfill Materials

40.9 Acknowledgment

Chapter 41. Conformal Coating

41.1 Introduction

41.2 Types of Conformal Coatings

41.3 Product Preparation

41.4 Application Processes

41.5 Cure, Inspection, and Finishing

41.6 Repair Methods

41.7 Design for Conformal Coating

References

Part 9 Solderability Technology

Chapter 42. Solderability: Incoming Inspection and Wet Balance Technique

42.1 Introduction

42.2 Solderability

42.3 Solderability Testing—a Scientific Approach

42.4 The Influence of Temperature on Test Results

42.5 Interpreting the Results: Wetting Balance Solderability Testing

42.6 Globule Testing

42.7 PCB Surface Finishes and Solderability Testing

42.8 Component Solderability

Chapter 43. Fluxes and Cleaning

43.1 Introduction

43.2 Assembly Process

43.3 Surface Finishes

43.4 Soldering Flux

43.5 Flux Form Versus Soldering Process

43.6 Rosin Flux

43.7 Water-Soluble Flux

43.8 Low Solids Flux

43.9 Cleaning Issues

43.10 Summary

References

Part 10 Solder Materials and Processes

Chapter 44. Soldering Fundamentals

44.1 Introduction

44.2 Elements of a Solder Joint

44.3 The Solder Connection to the Circuit Board

44.4 The Solder Connection to the Electrical Component

44.5 Common Metal-Joining Methods

44.6 Solder Overview

44.7 Soldering Basics

Chapter 45. Soldering Materials and Metallurgy

45.1 Introduction

45.2 Solders

45.3 Solder Alloys and Corrosion

45.4 PB-Free Solders: Search for Alternatives and Implications

45.5 PB-Free Elemental Alloy Candidates

45.6 Board Surface Finishes

References

Chapter 46. Solder Fluxes

46.1 Introduction to Fluxes

46.2 Flux Activity and Attributes

46.3 Flux: Ideal Versus Reality

46.4 Flux Types

46.5 Water-Clean (Aqueous) Fluxes

46.6 No-Clean Flux

46.7 Other Fluxing Caveats

48.8 Soldering Atmospheres

References

Chapter 47. Soldering Techniques

47.1 Introduction

47.2 Mass Soldering Methods

47.3 Oven Reflow Soldering

47.4 Wave Soldering

47.5 Wave Solder Defects

47.6 Vapor-Phase Reflow Soldering

47.7 Laser Reflow Soldering

47.8 Tooling and the Need for Coplanarity and Intimate Contact

47.9 Additional Information Sources

47.10 Hot-Bar Soldering

47.11 Hot-Gas Soldering

47.12 Ultrasonic Soldering

References

Chapter 48. Soldering Repair and Rework

48.1 Introduction

48.2 Hot-Gas Repair

48.3 Manual Solder Fountain

48.4 Automated Solder Fountain

48.5 Laser

48.6 Considerations for Repair

Reference

Part 11 Nonsolder Interconnection

Chapter 49. Press-Fit Interconnection

49.1 Introduction

49.2 The Rise of Press-Fit Technology

49.3 Compliant Pin Configurations

49.4 Press-Fit Considerations

49.5 Press-Fit Pin Materials

49.6 Surface Finishes and Effects

49.7 Equipment

49.8 Assembly Process

49.9 Press Routines

49.10 PWB Design and Board Procurement Tips

49.11 Press-Fit Process Tips

49.12 Inspection and Testing

49.13 Soldering and Press-Fit Pins

References

Chapter 50. Land Grid Array Interconnect

50.1 Introduction

50.2 LGA and the Environment

50.3 Elements of the LGA System

50.4 Assembly

50.5 Printed Circuit Assembly (PCA) Rework

50.6 Design Guidelines

Reference

Part 12 Quality

Chapter 51. Acceptability and Quality of Fabricated Boards

51.1 Introduction

51.2 Specific Quality and Acceptability Criteria by PCB Type

51.3 Methods for Verification of Acceptability

51.4 Inspection Lot Formation

51.5 Inspections Categories

51.6 Acceptability and Quality After Simulated Solder Cycle(s)

51.7 Nonconforming PCBS and Material Review Board (MRB) Function

51.8 The Cost of the Assembled PCB

51.9 How to Develop Acceptability and Quality Criteria

51.10 Class of Service

51.11 Inspection Criteria

51.12 Reliability Inspection Using Accelerated Environmental Exposure

Chapter 52. Acceptability of Printed Circuit Board Assemblies

52.1 Understanding Customer Requirements

52.2 Handling to Protect the PCBA

52.3 PCBA Hardware Acceptability Considerations

52.4 Component Installation or Placement Requirements

52.5 Component and PCB Solderability Requirements

52.6 Solder-Related Defects

52.7 PCBA Laminate Condition, Cleanliness, and Marking Requirements

52.8 PCBA Coatings

52.9 Solderless Wrapping of Wire to Posts (Wire Wrap)

52.10 PCBA Modifications

References

Chapter 53. Assembly Inspection

53.1 Introduction

53.2 Definition of Defects, Faults, Process Indicators, and Potential Defects

53.3 Reasons for Inspection

53.4 Lead-Free Impact on Inspection

53.5 Miniaturization and Higher Complexity

53.6 Visual Inspection

53.7 Automated Inspection

53.8 Three-Dimensional Automated Solder Paste Inspection

53.9 PRE-Reflow Aoi

53.10 Post-Reflow Automated Inspection

53.11 Implementation of Inspection Systems

53.12 Design Implications of Inspection Systems

References

Chapter 54. Design for Testing

54.1 Introduction

54.2 Definitions

54.3 AD HOC Design for Testability

54.4 Structured Design for Testability

54.5 Standards-Based Testing

References

Chapter 55. Loaded Board Testing

55.1 Introduction

55.2 The process of Test

55.3 Definitions

55.4 Testing Approaches

55.5 In-Circuit Test Techniques

55.6 Alternatives to Conventional Electrical Tests

55.7 Tester Comparison

References

Part 13 Reliability

Chapter 56. Conductive Anodic Filament Formation

56.1 Introduction

56.2 Understanding CAF Formation

56.3 Electrochemical Migration and Formation of CAF

56.4 Factors that Affect CAF Formation

56.5 Test Method for CAF-Resistant Materials

56.6 Manufacturing Tolerance Considerations

References

Chapter 57. Reliability of Printed Circuit Assemblies

57.1 Fundamentals of Reliability

57.2 Failure Mechanisms of PCBS and Their Interconnects

57.3 Influence of Design on Reliability

57.4 Impact of PCB Fabrication and Assembly on Reliability

57.5 Influence of Materials Selection on Reliability

57.6 Burn-in, Acceptance Testing, and Accelerated Reliability Testing

57.7 Summary

References

Further Reading

Chapter 58. Component-to-PWB Reliability: The Impact of Design Variables and Lead Free

58.1 Introduction

58.2 Packaging Challenges

58.3 Variables that Impact Reliability

References

Chapter 59. Component-to-PWB Reliability: Estimating Solder-Joint Reliability and the Impact of Lead-Free Solders

59.1 Introduction

59.2 Thermomechanical Reliability

59.3 Mechanical Reliability

59.4 Finite Element Analysis (FEA)

References

Part 14 Environmental Issues

Chapter 60. Process Waste Minimization and Treatment

60.1 Introduction

60.2 Regulatory Compliance

60.3 Major Sources and Amounts of Wastewater in a Printed Circuit Board Fabrication Facility

60.4 Waste Minimization

60.5 Pollution Prevention Techniques

60.6 Recycling and Recovery Techniques

60.7 Alternative Treatments

60.8 Chemical Treatment Systems

60.9 Advantages and Disadvantages of Various Treatment Alternatives

Part 15 Flexible Circuits

Chapter 61. Flexible Circuit Applications and Materials

61.1 Introduction to Flexible Circuits

61.2 Applications of Flexible Circuits

61.3 High-Density Flexible Circuits

61.4 Materials for Flexible Circuits

61.5 Substrate Material Properties

61.6 Conductor Materials

61.7 Copper-Clad Laminates

61.8 Coverlay Material

61.9 Stiffener Materials

61.10 Adhesive Materials

61.11 Restriction of Hazardous Substances (RoHS) Issues

Chapter 62. Design of Flexible Circuits

62.1 Introduction

62.2 Design Procedure

62.3 Types of Flexible Circuits

62.4 Circuit Designs for Flexibility

62.5 Electrical Design of the Circuits

62.6 Circuit Designs for Higher Reliability

62.7 Circuit Designs for RoHS Compliance

Chapter 63. Manufacturing of Flexible Circuits

63.1 Introduction

63.2 Special Issues with HDI Flexible Circuits

63.3 Basic Process Elements

63.4 New Processes for Fine Traces

63.5 Coverlay Processes

63.6 Surface Treatment

63.7 Blanking

63.8 Stiffener Processes

63.9 Packaging

63.10 Roll-to-Roll Manufacturing

63.11 Dimension Control

Chapter 64. Termination of Flexible Circuits

64.1 Introduction

64.2 Selection of Termination Technologies

64.3 Permanent Connections

64.4 Semipermanent Connections

64.5 Nonpermanent Connections

64.6 High-Density Flexible Circuit Termination

Chapter 65. Multilayer Flex and Rigid/Flex

65.1 Introduction

65.2 Multilayer Rigid/flex

Chapter 66. Special Constructions of Flexible Circuits

66.1 Introduction

66.2 Flying-Lead Construction

66.3 Tape Automated Bonding

68.4 Microbump Arrays

66.5 Thick-Film Conductor Flex Circuits

66.6 Shielding of the Flexible Cables

66.7 Functional Flexible Circuits

Chapter 67. Quality Assurance of Flexible Circuits

67.1 Introduction

67.2 Basic Concepts in Flexible Circuit Quality Assurance

67.3 Automatic Optical Inspection Systems

67.4 Dimensional Measurements

67.5 Electrical Tests

67.6 Inspection Sequence

67.7 Raw Materials

67.8 Flexible Circuit Feature Inspection

67.9 Standards and Specifications for Flexible Circuits

Appendix

Glossary

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

Index