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1、Chapter17CarbonNanotubesforThermalManagementofMicrosystemsJohanLiu(*ü)andTengWang17.1IntroductionOneimportantfunctionofelectronicpackagingistoremovetheheatgeneratedbytheintegratedcircuits(ICs).Efficientcoolingrequiresbothhighheatconductionwithinthepack
2、ageandefficientheatremovalfromthepackage.Elevatedtempera-tureisdamagingtothechipanditspackage.Materialmismatchcausesmechanicalstressleadingtofatigue,creepandfinallyfailure;interconnectscanmeltandelec-tromigrationwithintheICisspeededup.Efficientheatremo
3、valisnotalwaysthecase.Plasticisacommonpackagingmaterialasitiselectricallyinsulatingandcheap.Thethermalconductivityis,however,low,about0.2Wm−1K−1comparedwiththatofmetals(aluminium220Wm−1K−1andcopper400Wm−1K−1).Otherimportantfactorsaretheheatspreadingand
4、thermalinterfacematerials.Thecom-ponentsareoftenmountedonapolymerboardwhichisonlycooledbyair.Theheattransfercoefficientisonly515Wm−2K−1fornaturalconvectionand15250Wm−2K−1forforcedconvectioningases[1].Aselectroniccircuitsgrowdenserandthepowerconsumption
5、perunitareaincreases,newmoreefficienttechnologiesforheatremovalarenecessary.HeatfluxesfromtheIContheorderof100Wcm−2(1,000,000Wm−2)arenotrare.Aheattransfercoefficient(includingapossibleareaenlargingfactor)of20,000Wm−2K−1isneededtoaccommodateaheatfluxof1
6、00Wcm−2atatemperaturedif-ferenceof50K.Theapplicationofnanotechnologiesisconsideredasarevolution-aryapproachtomeetthetougherrequirementsforthermalmanagementofmicrosystems(Fig.17.1).Therearetwopossibleapproachestoimprovethecoolingofmicroelectronicpackage
7、s.Thefirstistoimprovethethermalconductivityofthepackagingmaterialandpackagegeometry,sothatthethermalgradientwithinitbecomessmaller.J.LiuBionanoSystemsLaboratory,DepartmentofMicrotechnologyandNanoscience,ChalmersUniversityofTechnology,Kemivägen9RoomA517
8、,Se41296,Gothenburg,SwedenShanghaiUniversity,Shanghai,ChinaJ.E.Morris(ed.)Nanopackaging:NanotechnologiesandElectronicsPackaging,377DOI:10.1007/978-0-387-47326-0_17,©SpringerScience+BusinessMedia,LLC2008MMorris_Ch17.indd377orris_Ch17.ind
