Encapsulation Technologies for Electronic Applications book cover

Encapsulation Technologies for Electronic Applications

Electronics are used in a wide range of applications including computing, communication, biomedical, automotive, military and aerospace. They must operate in varying temperature and humidity environments including indoor controlled conditions and outdoor climate changes. Moisture, ionic contamination, heat, radiation and mechanical stresses are all highly detrimental to electronic devices and can lead to device failures. Therefore, it is essential that the electronic devices be packaged for protection from their intended environments, as well as to provide handling, assembly, electrical and thermal considerations.Currently, more than 99% of microelectronic devices are plastic encapsulated. Improvements in encapsulant materials, and cost incentives have stretched the application boundaries for plastic electronic packages. Many electronic applications that traditionally used hermetic packages such as military are now using commercial-off-the-shelf (COTS) plastic packages. Plastic encapsulation has the advantages of low cost, smaller form factors, and improved manufacturability. With recent trends in environmental awareness, new environmentally friendly or ' green' encapsulant materials (i.e. without brominated additives) have emerged. Plastic packages are also being considered for use in extreme high and low temperature electronics. 3-D packaging and wafer-level-packaging (WLP) require unique encapsulation techniques. Encapsulant materials are also being developed for micro-electro-mechanical systems (MEMS), bio-MEMS, bio-electronics, and organic light-emitting diodes (O-LEDs).This book offers a comprehensive discussion of encapsulants in electronic applications. The main emphasis is on the encapsulation of microelectronic devices; however, the encapsulation of connectors and transformers is also addressed. This book discusses 2-D and 3-D packaging and encapsulation, encapsulation materials including environmentally friendly 'green' encapsulants, and the properties and characterization of encapsulants. Furthermore, this book provides an extensive discussion on defects and failures related to encapsulation, how to analyze such defects and failures, and how to apply quality assurance and qualification process for encapsulated packages. This book also provides information on the trends and challenges of encapsulation and microelectronic packages including application of nanotechnology.

Audience
Electronics and micro-electronics industry professionals, semiconductor chip and wafer designers, anyone interested in electronic packaging.

Hardbound, 504 Pages

Published: June 2009

Imprint: William Andrew

ISBN: 978-0-8155-1576-0

Contents


  • Preface

    1 Introduction

    1.1 Historical Overview

    1.2 Electronic Packaging

    1.3 Encapsulated Microelectronic Packages

    1.3.1 2D Packages

    1.4 Hermetic Packages

    1.4.1 Metal Packages

    1.4.2 Ceramic Packages

    1.5 Encapsulants

    1.5.1 Plastic Molding Compounds

    1.5.2 Other Plastic Encapsulation Methods

    1.6 Plastic versus Hermetic Packages

    1.6.1 Size and Weight

    1.6.2 Performance

    1.6.3 Cost

    1.6.4 Hermeticity

    1.6.5 Reliability

    1.6.6 Availability

    1.7 Summary

    References

    2 Plastic Encapsulant Materials

    2.1 Chemistry Overview

    2.1.1 Epoxies

    2.1.2 Silicones

    2.1.3 Polyurethanes

    2.1.4 Phenolics

    2.2 Molding Compounds

    2.2.1 Resins

    2.2.2 Curing Agents or Hardeners

    2.2.3 Accelerators

    2.2.4 Fillers

    2.2.5 Coupling Agents

    2.2.6 Stress-Relief Additives

    2.2.7 Flame Retardants

    2.2.8 Mold-Release Agents

    2.2.9 Ion-Trapping Agents

    2.2.10 Coloring Agents

    2.2.11 Market Conditions and Manufacturers of Encapsulant Materials

    2.2.12 Material Properties of Commercially Available Molding Compounds

    2.2.13 Materials Development

    2.3 Glob-Top Encapsulants

    2.4 Potting and Casting Encapsulants

    2.4.1 Dow Corning Materials

    2.4.2 General Electric Materials

    2.5 Underfi ll Encapsulants

    2.6 Printing Encapsulants

    2.7 Environmentally Friendly or “Green” Encapsulants

    2.7.1 Toxic Flame Retardants

    2.7.2 Green Encapsulant Material Development

    2.8 Summary

    References

    3 Encapsulation Process Technology

    3.1 Molding Technology

    3.1.1 Transfer Molding

    3.1.2 Injection Molding

    3.1.3 Reaction-Injection Molding

    3.1.4 Compression Molding

    3.1.5 Comparison of Molding Processes

    3.2 Glob-Topping Technology

    3.3 Potting and Casting Technology

    3.3.1 One-Part Encapsulants

    3.3.2 Two-Part Encapsulants

    3.4 Underfilling Technology 154

    3.4.1 Conventional Flow Underfill

    3.4.2 No-flow Underfill

    3.5 Printing Encapsulation Technology

    3.6 Encapsulation of 2D Wafer-Level Packages

    3.7 Encapsulation of 3D Packages

    3.8 Cleaning and Surface Preparation

    3.8.1 Plasma Cleaning

    3.8.2 Deflashing

    3.9 Summary

    References

    4 Characterization of Encapsulant Properties

    4.1 Manufacturing Properties

    4.1.1 Spiral Flow Length

    4.1.2 Gelation Time

    4.1.3 Bleed and Flash

    4.1.4 Rheological Compatibility

    4.1.5 Polymerization Rate

    4.1.6 Curing Time and Temperature

    4.1.7 Hot Hardness

    4.1.8 Post-cure Time and Temperature

    4.2 Hygro-thermomechanical Properties

    4.2.1 Coefficient of Thermal Expansion and Glass Transition Temperature

    4.2.2 Thermal Conductivity

    4.2.3 Flexural Strength and Modulus

    4.2.4 Tensile Strength, Elastic and Shear Modulus, and %Elongation

    4.2.5 Adhesion Strength

    4.2.6 Moisture Content and Diffusion Coefficient

    4.2.7 Coefficient of Hygroscopic Expansion

    4.2.8 Gas Permeability

    4.2.9 Outgassing

    4.3 Electrical Properties

    4.4 Chemical Properties

    4.4.1 Ionic Impurity (Contamination Level)

    4.4.2 Ion Diffusion Coefficient

    4.4.3 Flammability and Oxygen Index

    4.5 Summary

    References

    5 Encapsulation Defects and Failures

    5.1 Overview of Package Defects and Failures

    5.1.1 Package Defects

    5.1.2 Package Failures

    5.1.3 Classification of Failure Mechanisms

    5.1.4 Contributing Factors

    5.2 Encapsulation Defects

    5.2.1 Wire Sweep

    5.2.2 Paddle Shift

    5.2.3 Warpage

    5.2.4 Die Cracking

    5.2.5 Delamination

    5.2.6 Voids

    5.2.7 Non-uniform Encapsulation

    5.2.8 Flash

    5.2.9 Foreign Particles

    5.2.10 Incomplete Cure

    5.3 Encapsulation Failures

    5.3.1 Delamination

    5.3.2 Vapor-Induced Cracking (Popcorning)

    5.3.3 Brittle Fracture

    5.3.4 Ductile Fracture

    5.3.5 Fatigue Fracture

    5.4 Failure Accelerators

    5.4.1 Moisture

    5.4.2 Temperature

    5.4.3 Exposure to Contaminants and Solvents

    5.4.4 Residual Stresses

    5.4.5 General Environmental Stress

    5.4.6 Manufacturing and Assembly Loads

    5.4.7 Combined Load-Stress Conditions

    5.5 Summary

    References

    6 Defect and Failure Analysis Techniques for Encapsulated Microelectronics

    6.1 General Defect and Failure Analysis Procedures

    6.1.1 Electrical Testing

    6.1.2 Non-destructive Evaluation

    6.1.3 Destructive Evaluation

    6.2 Optical Microscopy

    6.3 Scanning Acoustic Microscopy

    6.3.1 Imaging Modes

    6.3.2 C-Mode Scanning Acoustic Microscope

    6.3.3 Scanning Laser Acoustic Microscope

    6.3.4 Case Studies

    6.4 X-ray Microscopy

    6.4.1 X-ray Generation and Absorption

    6.4.2 X-ray Contact Microscope

    6.4.3 X-ray Projection Microscope

    6.4.4 High-Resolution Scanning X-ray Diffraction Microscope

    6.4.5 Case Study: Encapsulation in Plastic-Encapsulated Devices

    6.5 X-ray Fluorescence Spectroscopy

    6.6 Electron Microscopy

    6.6.1 Electron-Specimen Interaction

    6.6.2 Scanning Electron Microscopy

    6.6.3 Environmental Scanning Electron Microscopy (ESEM)

    6.6.4 Transmission Electron Microscopy

    6.7 Atomic Force Microscopy

    6.8 Infrared Microscopy

    6.9 Selection of Failure Analysis Techniques

    6.10 Summary

    References

    7 Qualification and Quality Assurance

    7.1 A Brief History of Qualification and Reliability Assessment

    7.2 Qualification Process Overview

    7.3 Virtual Qualification

    7.3.1 Life-Cycle Loads

    7.3.2 Product Characteristics

    7.3.3 Application Requirements

    7.3.4 Reliability Prediction using PoF Approach

    7.3.5 Failure Modes, Mechanisms, and Effects Analysis (FMMEA)

    7.4 Product Qualification

    7.4.1 Strength Limits and Highly Accelerated Life Test

    7.4.2 Qualification Requirements

    7.4.3 Qualification Test Planning

    7.4.4 Modeling and Validation

    7.4.5 Accelerated Testing

    7.4.6 Reliability Assessment

    7.5 Qualification Accelerated Tests

    7.5.1 Steady-State Temperature Test

    7.5.2 Thermal Cycling Test

    7.5.3 Tests That Include Humidity

    7.5.4 Solvent Resistance Test

    7.5.5 Salt Atmosphere Test

    7.5.6 Flammability and Oxygen Index Test

    7.5.7 Solderability

    7.5.8 Radiation Hardness

    7.6 Industry Practices

    7.7 Quality Assurance

    7.7.1 Screening Overview

    7.7.2 Stress Screening and Burn-In

    7.7.3 Screen Selection

    7.7.4 Root-Cause Analysis

    7.7.5 Economy of Screening

    7.7.6 Statistical Process Control

    7.8 Summary

    References

    8 Trends and Challenges

    8.1 Microelectronic Device Structure and Packaging

    8.2 Extreme High- and Low-Temperature Electronics

    8.2.1 High Temperatures

    8.2.2 Low Temperatures

    8.3 Emerging Technologies

    8.3.1 Microelectromechanical Systems

    8.3.2 Bioelectronics, Biosensors, and Bio-MEMS

    8.3.3 Nanotechnology and Nanoelectronics

    8.3.4 Organic Light-Emitting Diodes, Photovoltaics, and Optoelectronics

    8.4 Summary

    References

    Index


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