Table Of ContentFine Pitch Surface
Mount Technology
Quality, Design, and
Manufacturing Techniques
Phil P. Marcoux
PPM Associates, Inc.
Sunnyvale, CA
~
SPRINGER SCIENCE+BUSINESS MEDIA, LLC
Copyright© 1992 by Springer Science+Business Media New York
Originally published by Van Nostrand Reinhold in 1992
Softcover reprint of the hardcover 1s t edition 199 2
Library ofCongress Catalog Card Number 92-3241
ISBN 978-1-4613-6567-9
Ali rights reserved. No part of this work covered by the copyright hereon may be
reproduced or used in any forrn by any means-graphics, electronic, or mechanical,
including photocopying, recording, taping, or information storage and retrieval
systems- without written permission of the publisher.
16 15 14 13 12 Il 10 9 8 7 6 5 4 3 2 1
Library orCongress Cataloging-in-Publication Data
Marcoux, Phil P.
Fine pitch surface mount technology : quality, design, and manufacturing
techniques Phil P. Marcoux.
p. cm. (Electrica] engineering series)
ISBN 978-0-442-00862-8 ISBN 978-1-4615-3532-4 (eBook)
DOI 10.1007/978-1-4615-3532-4
1. Integrnted cîrcuits-Design and construction. 1. Title.
II. Series.
TK7874.M259 1992 92-3241
621.381 'S-dc20 CIP
Dedication
Thistextisdedicatedtomyfather, PhilJ.,andmy mother,Cecelia,foralloftheir
sacrificesthatenabledmetoacquiretheeducationandincentivetoaccomplishthis
text, thefounding ofmy threecompanies,andsomuchmore.
This text isalsodedicated to my wife, Annforhersupportandunderstanding.
And tomychildrenDanielleand Paul,sothey canbuildfrom here.
And finally this text isdedicated to eachreader in thehope thatit will provide
a few seedsofwisdomfrom which highqualityelectronicassemblies will grow.
Contents
Preface ix
Acknowledgments xi
1 Introduction to Fine Pitch Technology (FPT) 1
1.0INTRODUCTION 1
1.1 WHATISFPT? 4
1.2THEBENEFITSOFFINEPITCHTECHNOLOGY 7
1.3THEMOTIVATIONFORFINEPITCHTECHNOLOGY 16
1.4COMPARISONOFFPTWITHTHROUGH-HOLEAND SURFACE
MOUNTTECHNOLOGIES 19
1.5FINEPITCHTECHNOLOGYOBSTACLES AND ISSUES 25
2 The Family ofFPT Packages 29
2.0THEEVOLUTIONOFFPTPACKAGES 29
2.1 INTRODUCTIONANDCONSTRUCTIONOFFINEPITCH
PACKAGES 29
2.2QUAD FLATPACKAGES 30
2.3PLASTICQUADFLATPACKAGES 36
2.4 SMALLOUTLINEPACKAGES 38
2.5TAPEAUTOMATEDBONDEDANDGUARDRING
PACKAGES 42
2.6PACKAGEHANDLINGAND
SHIPPING 46
2.7 PACKAGERELIABILITYANDQUALITY 51
2.8ISSUESWHEN SELECTINGANFPTPACKAGE 64
v
vi Contents
3 Fine Pitch Product Applications 68
3.0APPLICATIONS 68
3.1 PRODUCTAPPLICATIONS 68
3.2PACKAGEUSAGE 74
4 Printed Circuit Boards for Fine Pitch Technology 76
4.0BASICPCBPROCESSING 76
4.1 MATERIALOPTIONSANDPROPERTIES 80
4.2FABRICATIONANDASSEMBLYISSUES 95
4.3COMPOSITEELECTRICALPROPERTIES 99
4.4COMPOSITETHERMALPROPERTIES 104
5 Solderand Application Methods 107
5.0SOLDER 107
5.1 SOLDERALLOYCHOICES 108
5.2FLUX 112
5.3SOLVENTSANDTHIXOTROPES 118
5.4SPECIFYINGAPASTE 119
5.5 STORAGE 123
5.6PASTEQUALITYCONTROLANDTESTING 125
5.7APPLYINGSOLDERPASTE 128
6 Package Placement 149
6.0PLACEMENT 149
6.1 PLACEMENTOPTIONS 155
6.2ADDITIONALPLACEMENTSYSTEMFEATURES 164
6.3THROUGHPUTREQUIREMENTS 167
7 SolderReflow 169
7.0REFLOWDEFINED 169
7.1 THEDYNAMICS OFTHEREFLOWPROCESS 169
7.2 THEHEATSOURCE 174
7.3 SELECTINGAREFLOWMETHOD 191
7.4CHANGINGCOMPONENTLOCATIONDURINGREFLOW 197
Contents vii
8 Post Reflow Cleaning 200
8.1 SUCCESSFULNO-CLEAN 201
9 Inspection, Rework, and Repair 206
9.0INSPECTION 206
9.1 REWORKANDREPAIR 213
10 Design for Reliability Guidelines 218
10.1 DEFINING SOLDERJOINTRELIABILITY 218
10.3CAUSEOFSOLDERJOINTFATIGUE 221
10.4SOLDERJOINTPREDICTIONMODELS 228
10.5ELECTRONICPRODUCTUSECONDITIONS 234
10.6GENERALDESIGNFORRELIABILITYGUIDELINES 236
11 Design for Testability 241
11.0BASICS OFELECTRICALTESTINGPCAS 241
11.1 CONTACTINGTHEASSEMBLY 241
11.2DISADVANTAGES OFIN-CIRCUITTESTING 244
11.3ALTERNATIVESTOIN-CIRCUITTESTING 246
11.4SUCCESSFULLYUSING ICTFORFPTTESTING 253
12 Design for Manufacturability 265
12.0GENERALDFMGUIDELINES 265
12.1 THERULES OFDFM 267
12.2IMPLEMENTINGDFM 276
12.3DFM SUMMARY 282
13 Specific Design Guidelines for FPT Packages 284
13.1 PACKAGESELECTION 285
13.2 PACKAGEPLACEMENT
ONTHEBOARD 296
13.3LANDPATTERN SIZE 300
13.4TRACEROUTINGAND PROTECTION 304
13.5THERMALMANAGEMENT 307
13.6FABRICATIONOFTHEBOARD 309
13.7 STENCILFABRICATION 317
viii Contents
AppendixA Addresses ofStandards Organizations 319
Appendix B Summary ofSMT SemiconductorOutlines
from JEDEC Publication 95 320
Appendix C Summary ofImportant Component, Material,
Process and Design Standards 323
Glossary 329
Index 334
Preface
Finepitchhighleadcountintegratedcircuitpackagesrepresentadramaticchange
from the conventional methodsofassemblingelectroniccomponents to a printed
interconnectcircuitboard.Tosome,theseFPTpackagesappeartobeanextension
ofthe assembly technology called surface mountor SMT. Many ofus who have
spenta significant amount oftime developing the processand design techniques
forthesefinepitchpackageshaveconcludedthatthesetechniquesgobeyondthose
commonlyuseedforSMT.In 1987thepresentauthor,convincedoftheuniqueness
oftheassemblyanddesigndemandsofthesepackages,chairedajointcommittee
wherethemembersagreedtousefinepitchtechnology (FPT)asthedefiningterm
for these demands. The committee was unique in several ways,one beingthat it
was thefirst time three U.S. standards organizations, the IPC (Lincolnwood, IL),
theEIA(Washington,D.C.),andtheASTM(Philadelphia),cametogethertocreate
standardsbeforeatechnology was inhighdemand.
The term fine pitch technology and its acronym FPT have since become
widely accepted in the electronics industry. The knowledge of the terms and
demands of FPT currently exceed the usage of FPT packaged components, but
this is changing rapidly because of the size, performance, and cost savings of
FPT.
Ihave resistedseveral past invitationsto writeothertechnical texts. However,
Ifeel thereareimportantadvantagesandsignificantdifficultiestobeencountered
with FPT. My motivation in writing this text is to explain the advantages and
obstacles,and to offersomeofthe possiblesolutions to users ofFPTsothey can
enjoy the benefitssooner.
Inthistext,IpresenttwostrategiesfortheassemblyoftheFPTpackagestothe
substrate. One strategy is to incorporate the assembly directly in with the SMT
process. The other is to treat FPTas a secondary operation using a simultaneous
placement and reflow operation. I also present a strategy for developing design
guidelines to optimize for what I call "design for ability" which incorporates
manufacturability, quality, reliability, and repairability into the design of the
ix
x Preface
product. Thesestrategieswill be useful toall usersregardlessofwhetherthey are
inloworhigh volumeelectronicassembly.
FPToffersmanyofthebenefitssought,butnotachieved,byusersofSMT.With
SMT, productcostsavingsand reliability improvementshave beenelusive. With
proper planning, design,and hard work, many cost and reliability improvements
areachievedwithFPT.Ihopethistextalsohelpsthereaderachievetheseandother
benefitsfrom FPT.
PhilP. Marcoux
