Electrically conductive adhesives

436 Pages·2008·15.1 MB·English

by  R Gomatam

With all the environmental concerns and constraints
today and stricter future regulations, there is a patent
need to replace materials noxious to the environment
by environmentally-friendly alternatives. Electrically
conductive adhesives (ECAs) are one such example. ECAs
offer an excellent alternative to lead-solder interconnects
for microelectronic packaging applications. ECAs are
used in electronics for laptop computers, camcorders,
watch electronics, hard-drive suspensions and a myriad
of electronic equipments. Environmentally-friendly ECAs
offer many advantages vis-à-vis solder, such as simple
and low-temperature processing conditions, better thermo
mechanical performance and fi ner pitch.
Electrically
This book is based on the two Special Issues of the
Journal of Adhesion Science and Technology (JAST vol. 22,
no. 8-9 and vol. 22, no. 14) dedicated to this topic.
The book contains a total of 21 papers (refl ecting Conductive
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overviews and original research) and is divided into . l
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three parts as follows: Part 1: Introduction and Recent o c
Developments, Part 2: Mechanical, Durability and m tr
Reliability Aspects and Part 3: Characterization and at ic Adhesives
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Electrically Conductive Adhesives
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Electrically Conductive
Adhesives
Editedby
R. Gomatam and K. L. Mittal
LEIDEN • BOSTON
2008
CRC Press
Taylor & Francis Group
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Boca Raton, FL 33487-2742
© 2008 by Koninklijke Brill NV Leiden The Netherlands
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Version Date: 20120525
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Contents
Preface vii
Part1:IntroductionandRecentDevelopments
UsingElectricallyConductiveInksandAdhesivesasaMeanstoSatisfy
EuropeanPCBManufacturingDirectives
H.J.LewisandA.Ryan 3
AnOverviewoftheUseofElectricallyConductiveAdhesives(ECAs)as
aSolderReplacement
H.J.LewisandF.M.Coughlan 25
ElectricallyConductiveAdhesivesforElectronicPackagingand
AssemblyApplications
L.J.Matienzo,R.N.DasandF.D.Egitto 39
AnisotropicConductiveAdhesivesforFlip-ChipInterconnects
W.Wang,Y.C.ChanandM.Pecht 57
ReviewofRecentAdvancesinElectricallyConductiveAdhesive
MaterialsandTechnologiesinElectronicPackaging
M.J.Yim,Y.Li,K.-s.Moon,K.W.PaikandC.P.Wong 79
RecentAdvancesinDevelopingHighPerformanceIsotropic
ConductiveAdhesives
D.D.LuandC.P.Wong 117
RecentAdvancesinNano-conductiveAdhesives
D.D.Lu,Y.G.LiandC.P.Wong 135
Part2:MechanicalDurabilityandReliabilityAspects
ReliabilityofAnisotropicConductiveAdhesiveJointsinElectronic
PackagingApplications
Y.C.LinandX.Chen 157
DropTestPerformanceofIsotropicElectricallyConductiveAdhesives
J.E.MorrisandJ.Lee 185
MechanicsofAdhesivelyBondedFlip-Chip-on-FlexAssemblies.
PartI:DurabilityofAnisotropicallyConductiveAdhesiveInterconnects
J.Haase,D.Farley,P.Iyer,P.Baumgartner,A.Dasgupta
andJ.F.J.Caers 203
vi Contents
MechanicsofAdhesivelyBondedFlip-Chip-on-FlexAssemblies.
PartII:EffectofBumpCoplanarityonManufacturabilityandDurability
ofNon-conductingAdhesiveAssemblies
D.Farley,A.DasguptaandJ.F.J.Caers 227
FatigueBehaviorofElectricallyConductiveAdhesives
B.SuandJ.Qu 251
AspectRatioandLoadingEffectsofMultiwallCarbonNanotubesin
EpoxyforElectricallyConductiveAdhesives
J.Li,J.K.Lumpp,R.AndrewsandD.Jacques 271
Part3:CharacterizationandProperties
NovelTechniquesforCharacterizationofFast-CureAnisotropic
ConductiveandNon-conductiveAdhesives
M.Teo 287
ChemorheologyofEpoxy/NickelConductiveAdhesivesDuring
ProcessingandCure
J.ZhouandE.Sancaktar 301
TemperatureCharacterizationinAnisotropicConductiveFilm
AdhesiveBonding
R.L.D.Zenner,C.T.MurrayandC.Fisher 327
OperatingTemperatureofAnisotropicConductingFilmAdhesives
R.Divigalpitiya 345
GeometricEffectsonMultilayerGenericCircuitsFabricatedUsing
ConductiveEpoxy/NickelAdhesives
J.ZhouandE.Sancaktar 357
StableandUnstableCapillaryFlowsofHighly-FilledEpoxy/Nickel
Suspensions
J.ZhouandE.Sancaktar 367
ElectricalPropertiesofCopper-FilledElectricallyConductiveAdhesives
andPressure-DependentConductionBehaviorofCopperParticles
Y.-S.LinandS.-S.Chiu 387
ExperimentalInvestigationandMicropolarModellingoftheAnisotropic
ConductiveAdhesiveFlip-ChipInterconnection
Y.Zhang,J.Liu,R.LarssonandI.Watanabe 411
Preface
These days the mantra is ‘Go Green, Think Green’. Every industry is trying
earnestlytoswitchtogreenproducts,greenprocessesandgreenmanufacturingand
theelectronics/microelectronicsindustryisnoexception.Withalltheenvironmen-
tal concerns and constraints today and stricter future regulations, there is a patent
need to replace materials noxious to the environment by environmentally-friendly
alternatives. Electrically conductive adhesives (ECAs)is one such example. ECAs
offeranexcellentalternativetolead–solderinterconnectsformicroelectronicpack-
agingapplications.ECAsareusedinelectronicsforlaptopcomputers,camcorders,
watch electronics, hard-drive suspensions and a myriad of electronic equipments.
Environmentally-friendly ECAs offer many advantages vis-à-vis solder, such as
simple and low-temperature processing conditions, better thermo-mechanical per-
formance and finer pitch. Even though ECAs have excellent potential for being an
efficient and less costly alternative to lead–solder interconnects, they still possess
a number of problems with regard to durability and design to meet specific needs.
Thus there has been a flurry of R&D activity in surmounting these problems and
concerns.
An ECA is essentially composed of a polymer resin (commonly an epoxy) and
an electrically conductive filler. Many different kinds of filler materials, ranging
from silver (commonly used) to carbon nanotubes, have been explored. Also they
are available in different formulations as Anisotropically Conductive Adhesives
(ACAs), Anisotropically Conductive Films (ACFs) and Isotropically Conductive
Adhesives (ICAs). So a user has a broad spectrum of products from which he/she
canchoosetheoptimumformulationdependingonperformancerequirements.
Soinlightofthecurrentintenseresearchactivityinamelioratingtheexistingfor-
mulationsordesigningnewandimprovedECAswedecidedtobringoutthisspecial
volume, which reflects the cumulative wisdom of many world-class researchers in
thisburgeoningfield.
ThisbookisbasedonthetwoSpecialIssuesoftheJournalofAdhesionScience
andTechnology(JAST)(Vol.22,Nos8–9,pp.795–1015(2008)andVol.22,No.14,
pp.1593–1797(2008))dedicatedtothistopic.Basedonthewidespreadinterestin
andtremendous importance ofECAs,wedecidedtomakethis bookavailable asa
ElectricallyConductiveAdhesives
©KoninklijkeBrillNV,Leiden,2008
viii Preface
single and easily accessible source of information. The papers as published in the
above-mentionedissueshavebeenre-arrangedmorelogicallyinthisbook.
The book contains a total of 21 papers (reflecting overviews and original re-
search) and are divided into three parts as follows: Part 1: Introduction and Re-
cent Developments; Part 2: Mechanical, Durability and Reliability Aspects; and
Part 3: Characterization and Properties. Topics covered include: various forms of
ECAs, viz., anisotropically conductive adhesives, anisotropically conductive films
and isotropically conductive adhesives; electrically conductive adhesives and inks
in PCB (Printed Circuit Board) manufacturing; ECAs as a solder replacement;
high performance isotropically conductive adhesives; ECAs in electronic packag-
ing;nano-conductiveadhesives;mechanical,durability,reliabilityandperformance
aspectsofECAs;fatiguebehaviorofECAs;carbonnanotubesforECAs;bulkchar-
acterization of ECAs using a variety of techniques; electrical properties of ECAs
andtheirconductionbehavior;andmodellingofECAflip-chipinterconnection.
ItisobviousthatmanydifferentaspectsandramificationsofECAsareaccorded
duecoverageinthisbookandthusthisbookrepresentsacomprehensivetreatiseon
thissubject.
Wecertainlyhopethatthisbookcontainingbountifulup-to-dateinformationwill
be of great interest and value to anyone interested in or passionate about finding
‘green’ alternatives in the electronics/microelectronics industry. Also we further
anticipatethatthisbook,representingacommentaryoncurrentresearchactivityin
thisimportantarena,willserveasafountainheadfornewideasandconcomitantly
newvistaswillemerge.
Nowcomesthepleasanttaskofthankingthosewhohelpedinmaterializingthis
book. First and forecast our thanks go to the authors for their interest, enthusiasm,
cooperation and contribution without which this book would not have been in the
hands of the readers. We profusely thank the unsung heroes (reviewers) for their
time and efforts in providing many valuable comments as comments from peers
are sine qua non to maintain the highest standard of a publication. Finally, our
appreciation goes to the appropriate individuals at Brill (publisher) for giving this
bookabodyform.
RAJESHGOMATAM
AdjunctProfessor
DepartmentofMechanicalEngineeringandMechanics
LehighUniversity,Bethlehem,PA18015
USA
and
K.L.MITTAL
P.O.Box1280
HopewellJct.,NY12533
USA
Part 1
Introduction and Recent Developments