A Concise Introduction to Ceramics

A Concise Introduction to Cera1l1ics

by

George C. Phillips

~ V AN NOSTRAND REINHOLD ~ ~ ____ New York

Copyright ('> 1991 by Van Nostrand Reinhold

Softcover reprint of the hardcover 1 st ed ition 1991

Library of COnRreSS Catalog Card Number 91·19587

ISBN·13: 978·94·011--6975·2 All rights reserved . No part of this work covered by the copyright hereon may be rcproduccd or uscd in any form or by any means-graphic. electronic. or meehaniclli. including photocopying. recording. taping. or information storage and retrieval systems-without written permission of the publisher.

Manufactured in the United States of America

Published by Van Nostrand Reinhold 11 5 Fifth Avenue New York. New York 10003

Chapman and H all 2- 6 Boundary Row London. SEI SHN. England

Thomas Nelson Austral ia 102 Dodds Street South Melbourne 3205 Victoria. Australia

Nelson Canada 11 20 Birchmounl Road Scarborough. Ontario M I K 5G4. Canada

16 15 14 13 12 II 10 9 8 7 6 5 4 3 2 Library or Congress Cataloging-in· Publication Data

Phillips. George C .. 1937-A concise inlrodu!;tion to ceramics/by George C. Phillips.

p. cm. Includes bibliographical referen!;es and index. ISBN-13: 978-94-011--6975-2 e-ISBN-13: 978-94-011--6973-8 001:10: 1007/978-94-011--6973-8

I. Cerami!;s. L Tille. TP807.P53 1991 666-dc20 9 1·19587

CIP

Contents

Preface / ix

Introduction / xiii

PART I-OVERVIEW OF CERAMICS

1. Ceramic Materials / 3 I. I Introduction / 3 1.2 Ceramic Materials / 4 1.3 Terminology / 6 1.4 Formula Notation / 7

2. Ceramic Raw Materials / 8 2.1 Naturally Occurring Minerals / 8 2.2 Manufactured Raw Materials / 10

3. Nature of Clay / 12 3.1 Physics of Clay / 12 3.2 Clay-Water Systems / 15

4. Forming from Powders / 18 4.1 Powder Preparation / 18 4.2 Dry Pressing / 18 4.3 Plastic Forming / 21 4.4 Casting / 22 4.5 Thermal Treatments / 24

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vi Contents

5. Forming from Melts / 27 5. 1 Cooling Curves / 27 5.2 Glass Forming Methods / 29 5.3 Thermal Conditioning Glass / 30

6. Miscellaneous Forming Techniques / 32 6.1 Coatings / 32 6.2 Single Crystals / 33 6.3 Miscellaneous Formings / 33

7. Traditional Ceramic Industries / 34 7.1 Abrasives / 34 7.2 Refractories / 35 7.3 White wares / 35 7.4 Structural Clay Products / 36 7.5 Glasses / 36 7.6 Porcelain Enamels / 37 7.7 Cements / 38

PART II-THE NATURE OF CERAMIC MATERIALS (BONDING/CRYST AL CONCEPTS)

8. Atomic Structure / 41 8.1 Background / 41 8.2 Electronic Configurations / 42 8.3 Ionization / 44

9. Bonding and Crystal Chemistry Concepts / 47 9.1 Types of Bonding / 47 9.2 Material Classes / 47 9.3 Pauling's Rules / 48 9.4 Coordination Numbers / 49 9.5 Bond Strength / 52

10. Silicate Stuctures / 53 10.1 Basis / 53 10.2 Types of Silicates / 54 10.3 Layer Minerals / 55

11. Structure of Glass / 60 11.1 Crystalline versus Glassy / 60

11.2 Glass Formers / 61 11.3 Glass Modifiers / 62

Contents vii

11.4 Structure and Composition versus Properties / 63

12. Oxide Crystal Structures / 65 12.1 Basis/65 12.2 ArnXn Compounds / 67 12.3 ABrnXn Compounds / 67

PART III-CHARACTERIZATION OF CERAMIC MATERIALS

13. Analytical Techniques / 71 13.1 Introduction / 71 13.2 Microscopy / 71 13.3 X-Ray Methods / 75 13.4 Surface Measurements / 80

14. Properties and Requirements of Ceramic Materials / 81 14.1 Introduction / 81 14.2 Properties / 81 14.3 Requirements / 84

15. Ceramic Surface Characteristics / 88 15.1 Introduction / 88 15.2 Dry-Pressed Alumina Surfaces / 88 15.3 Surface Variations versus Processing Techniques / 91 15.4 Quantitative Surface Techniques / 95

16. Ceramic Strength Considerations / 102 16.1 Introduction / 102 16.2 Strength Measurements / 103 16.3 Fracture Mechanics / 105

PART IV-HI-TECH APPLICATIONS OF CERAMICS

17. Structural and Electronic Applications / 115 17.1 Introduction / 115 17.2 Structural Applications / 116 17.3 Magnetic Ceramics / 117 17.4 Electronic Applications / 119

viii Contents

18. Integrated Circuit Technology / 122 18.1 Introduction / 122 18.2 Semiconductors / 122 18.3 Integrated Circuit Processing / 123 18.4 Transistor Structures / 125 18.5 Application and Development of Semiconductors / 126

19. Ceramic Packaging of IC Devices / 127 19.1 Introduction / 127 19.2 Package Designs / 128 19.3 Processing of Planar Substrates / 131 19.4 Future Trends in Planar Ceramic Packaging / 136 19.5 Multilayer Ceramics (MLC) / 141

20. The Future of Ceramics / 149

Index / 153

Preface

During the early 1970s, the IBM facility in Endicott, NY, began a signif­icant development and manufacturing effort to produce both thick- and thin-film wiring on ceramic substrates for semiconductor packaging. To fulfill the product mission it was necessary to provide specialized training in ceramics.

Participants in the resulting 15-week ceramics courses ranged from manufacturing personnel to engineers with bachelor's, master's, and doc­tor's degrees. Many were recent college graduates in disciplines ranging from mechanical engineering to materials science. Their organizational affiliations included manufacturing, manufacturing engineering, quality engineering, development engineering, product engineering, product as­surance, reliability engineering, production control, and purchasing. Their backgrounds and job assignments were very diverse.

As the ceramics technology spread within IBM, so did the need for education. As a result, three-day short courses were conducted at the company's facilities in Burlington, Vermont, and Bromont, Quebec.

More recently, the same basic ceramics course was taught at Broome Community College and Alfred University in their continuing education programs. It also was conducted upon invitation for personnel working at Coors Ceramics in Golden, Colorado.

As the course was developed and refined over a 15-year period, it became apparent that a textbook was needed to provide a basic introduc­tion to ceramics. Thus, the basis for this book was established. The book's general overview of ceramics-what they are, where they come from, how they are made, and how they are used-came from the au­thor's undergraduate study at Alfred University. The crystal chemistry

ix

x Preface

concepts are based on his graduate study at Alfred University in crystal chemistry, clay mineralogy, and structure of glass. Chapters on charac­terization of ceramic materials resulted from the combination of a mas­ter's thesis and laboratory investigations. Finally, the hi-tech applications portion of the book is based on the author's experiences at IBM.

The purpose of this textbook is to provide an introductory overview of ceramics for people who are working with ceramic materials and for college students involved with the materials sciences. It is not designed to replace Kingery, Bowen, and Uhlmann's [I] Introduction to Ceramics. which is an excellent reference for students or scientists who already have some background in ceramics. This book provides the necessary foundation for future studies or involvement with ceramics.

Acknowledgments

I am grateful to the following individuals who played key roles in helping me formulate the classroom version of A Concise Introduction to Ce­ramics: Ken Jordan, IBM, Austin, Texas; Charles Quagliata, Broome Community College, Binghamton, NY; Coral Link, Alfred University, Alfred, NY; William Flock, Coors Ceramics Company, Golden, CO; Vivian Harwood Mattox, Materials Research Society; and James CIum, State University of New York at Binghamton. They each, in their own way, gave me an opportunity to collect my thoughts, hone my skills, and teach. Their encouragement provided the impetus for this book.

I also wish to thank Bob Sebesta from IBM for editing the chemistry section, and David Yetter, a technical editor at IBM, who edited the manuscript with insight and thoroughness and guided me through the publishing process.

xi

Introduction

Part I presents a general overview of the field of ceramics, defining what constitutes a ceramic material and providing examples of the different types of ceramics. A distinction is made between naturally occuring raw materials that can be used "as found" and manufactured raw materials that, because of their unique compositions, require synthesis.

Clay is shown to be the most important ceramic raw material for traditional ceramic products, possessing unique characteristics that are a key to ceramic forming techniques. Forming from powders is presented, based on the ratio of clay to water. The process description continues, from densification of the initial formed shapes, through high temperature treatments, to the rocklike condition associated with ceramics.

Glass is shown to differ from other ceramic products more in the method of manufacture than in its chemical or physical properties. Glasses are formed from a high temperature viscous state with cooling that is rapid enough to cause the bulk material to solidify prior to crystal­lization.

Applications of ceramic materials are highlighted by reviewing the ceramic industries. Traditional uses are covered, including a variety of products from dishes to electronic components. The intent is to show that most applications for ceramics are based on one outstanding character­istic of the material, such as hardness (abrasives), thermal resistance (refractories), transparency (glass), or durability (whitewares).

Part II discusses the crystal structures of ceramic materials and their resulting characteristics. Ceramics are presented as a class of materials along with metals and plastics. These materials differ from each other in their properties because of the initial attraction, or bonding, of their

xiii

xiv Introduction

elements. The bonding concepts presented are based on atomic structure and the consequences of ionization to charged ions, where the ionic bond in ceramic materials results from the electrostatic attraction of positive ions (cations) and negative ions (anions).

Differences within a class of materials are due not only to the different elements but also to the arrangement of the elements. If the arrangement is regular and reproducible, then the structure is crystalline. Crystal chemistry concepts are developed by using cations such as silicon, alu­minum, and magnesium as the reference, and then constructing oxygen anion tetrahedrons and octahedrons around the cations.

The largest group of ceramic materials is the silicates. This includes clays, talc, and micas, which are considered to be built by using silicon tetrahedrons as building blocks. Glass, which also is primarily made from silicon tetrahedrons, differs from these materials in that its arrangement is irregular or random. This difference produces unequal bond strengths in glass, which result in melting "ranges" rather than specific melting temperatures. It is shown that glassy materials therefore can be formed in a high temperature viscous state.

The other oxide crystals (nonsilicates) are developed by using the anion as a reference point, and include the close packed oxygens, such as body-centered cubic, face-centered cubic, and hexagonal close packed structures, where the cations occupy interstitial sites that are fourfold (tetrahedra) and sixfold (octahedra). The unique characteristics of fer­romagnetics and ferroelectrics, which are related to their close packed crystal structures, are described.

Part III concerns characteristics of ceramic materials. Analytical tech­niques such as microscopy, X-ray analysis, and surface analysis are de­scribed briefly, and properties that dictate the uses of ceramics and dimensional tolerancing are presented. The effect of ceramic surfaces on processing is highlighted by using thin-film metal to enhance the differ­ences. Also, strength considerations are presented, with measurement techniques and failure analysis from various fracture modes.

Part IV presents some of the high-technology applications for ce­ramics. This section includes structural or mechanical uses of the newer materials such as silicon nitride, stabilized zirconia, and aluminum ni­tride. A discussion of the magnetic behavior of the ferrite materials leads to some of the unique applications of magnetic ceramic materials. Linear and nonlinear dielectric applications such as uses in capacitors and trans­ducers also are explained.

Then an overview of integrated circuit technology-including designs, manufacture, and applications-is presented as the basis for understand­ing electronic packaging technologies. Ceramic packaging is described

Introduction xv

from chip connections to package input/output connections. Thick- and thin-film wiring is illustrated for both planar and multilayer designs. Fi­nally, future trends in ceramic packaging are presented, including in­creased I/Os, denser wiring, and electrical and thermal performance improvements.

The final chapter on the future of ceramics provides some brief thoughts on growth fields. It focuses on the use of ceramics in hostile environments where improved thermal and fracture resistance will be critical, and in hi-tech applications in electronics, fiber optics, and super­conductivity.

A Concise Introduction to Ceramics