Icepak高级培训教材

AdvancedThermalModelingAdvancedIcepak高级建模Fluent.incCourseOutline1.Introduction简介2.PrintedCircuitBoards(PCB板)3.ICPackages(IC封装)4.HeatSinks散热器5.InterfaceResistance接触热阻6.Fans,ImpellersandBlowers风扇，叶轮，离心风机7.AltitudeEffects高度的影响8.FlowResistances气流阻尼9.Radiation幅射10.HeatPipes热管11.JouleHeating电阻发热12.ThermoelectricCoolers热电冷却CourseOutline13.ColdPlates冷板14.Transformers变压器15.FlowBaffles气流挡板16.WallEffects壁的效果17.ExternalCoolers/Heaters外部冷却器/加热器Exercises:

练习：1.PBGAModelPBGA模型2.SelectingaHeatSink选择散热器3.ModelingTEC

热电冷却器模型4.SelectingaBaffle选择挡板5.ModelingExternalCoolers外部冷却器建模IntroductionIntroduction简介TheCaseforThermalManagementTheheatgeneratedinanelectroniccircuitisinverselyproportionaltotheefficiencyofthecircuit电子线路板产生的热与它的效率成反比Thepowerthatisnotconvertedtoperformusefulelectromagneticworkislostintheformofheattothesurroundings没有转换成电磁功率的热耗散到了周围的环境Thepowerwastedasheatincludes:热耗包括Jouleheating(I2R)loss电阻损失Powersupply电能提供Thereliabilityofasemiconductordeviceisdirectlyaffectedbyitsoperatingtemperature

工作环境的温度直接影响到半导体设备的可靠性TheCaseforThermalManagementVirtuallyallelectronicfailuremechanismsareenhancedbytheincreaseinpackagetemperature:

实际上，所有电子失效的机理都是由于封装温度升高引起的StressesduetoTCE(=TotalCompositeError总综合误差）mismatch不匹配Corrosion腐蚀Electro-migration电子移动Oxidebreakdown氧化物崩溃Currentleakage(whichdoubleswithevery10cinactivedevices)电流泄漏Degradationinelectricalperformance(duetochangeindeviceparameters)电性能下降TheCaseforThermalManagementTherateoffailureofelectronicpackagesisdirectlyproportionaltoheatandincreasesexponentiallywiththemaximumtemperatureofthepackage

电子封装失效的比例直接与热成正比，而且与封装的最高温度成指数增长Therateoffailurecanbeexpressedas:

失效的比例可描述为：

F=Ae-E/KTwhere,F=failurerate,失效率

A=constant常数E=activationenergyinelectronvolts(eV)激活的电能K=Boltzmann’sconstant(8.63e-5eV/K),andT=junctiontemperatureinKTheCaseforThermalManagementTheCaseforThermalManagementTheEffectofPackageTemperatureonFailure(Numberoffailuresafter1000hrofoperationpermillionunits)

每百万个元件工作1000hr失效的数目TheCaseforThermalManagementMajorCausesofElectronicFailure电子失效的主要原因Source:U.S.AirforceAvionicsIntegrityProgram(Reynell,M.,1990)ICPackageTrendsPackagesaregettingthinner封装变薄Numberofleadsisgettinglargerleads数目增多Packagefootprintdecreasingtoapproachchipsize为满足chip的尺寸，封装的footprint降低Packagepinpitchisdecreasing封装的pinpitch减少Clockspeedisincreasing时钟速度提高ICchipsareperformingmorecomplextasks

ICchips功能更复杂Movingtowardssystem-on-chiptechnologyPackagesaredissipatingmorepower

功耗增加Operatingjunctiontemperatureremainsfixed工作的温度保持不变55Cforcommodityandhandhelddevices生活用品55C125Cforautomotivesystems汽车系统125CBudgetperwattofheatremovalisdecreasing每watt的预算减少PackagingTrendsPackagePowerProjectionTrends(Watts)封装功耗的发展趋势Commodity:Lowcost(<$300)consumerproductsHand-Held:Batterypowered(<$1000)productssuchascellular,etc.Cost/Performance:Maximumperformancewithcostlimit(<$300)(Notebooks,etc.)HighPerformance:Performanceistheprimarydriver(Servers,Avionics,etc.)HarshEnvironment:Automotive,Military,etc.CoolingMethodsTypesofcoolingmethods:散热方法种类：Naturalconvectionaircooling自然对流Forcedaircooling强迫对流Immersionliquidcooling浸润冷却Boiling蒸发冷却Heatpipes热管Coldplates冷板Thermoelectriccoolers热电冷却Microchannelcooling微通道冷却Microjet微喷射冷却Naturalconvectionaircoolingisusedforlowpowerapplications自然对流散热主要用于低功耗ItisthesimplestandcheapestcoolingmethodavailableCoolingMethodsForcedaircooling（强迫对流）isusedforrelativelylargeloadsofheat主要用于相对大的热耗Itrequiresafan,blower,etc.tomovetheairImmersioncoolingisusedtoremovelargeloadsofheatbyimmersingthecomponentsinsideinertdielectricfluidsuchasfluorocarbonorFreon浸润主要用于大热耗，通过将元件浸润到惰性非导热流体中，如碳氟化合物或氟利昂Typicalapplicationsincludemainframecomputers,supercomputers,high-powertransmitters,etc.Boilingheattransfer

（蒸发换热）istheabsorptionofheatbyaboilingfluidandisusedforhighpowerapplicationsAcoldplate（冷板）

isablockofmetal,liquid-cooledbyforcedconvection,onwhichcircuitcardsorcomponentsaremountedTheyareusedinmilitaryandhigh-powerelectronicapplications

主要是军用和高功耗电子设备CoolingMethodsMicrochannelCooling（微通道冷却）

isatechnologydealingwithverysmallfinsthatareplacedextremelyclosetotheheatdissipatingelementthecoolantcanbeliquidorgasThermoelctriccoolers（热电冷却）

aresolidstateheatpumpsthatdonothaveanymovingpartsnoranyworkingfluidTheymoveheatfromonelocationtoanotherthroughthePeltiereffectHeatpipes

（热管）aredevicesthatprovideapassivemethodoftransferringheatfromoneareatoanotherHeatisabsorbedatoneendthroughevaporationandisrejectedbycondensationattheoppositeendCoolingRoadmapNaturalConvectionModerateForcedAirAdvancedForcedAirLiquidCoolingCoolingRoadmapAirNaturalConvection+RadiationForcedAirConvectionImmersionNaturalConvectionFluorocarbonsImmersion-BoilingFlorocarbonsWaterForcedConvectionModesofHeatTransferThreemodelsofheattransfer:三种传热方式：Conduction传导Convection对流Radiation幅射Conductionisaprocessinwhichheatflowsbetweentwomedia(solid,liquidorgas)thatareindirectcontactwithoneanother

传导是发生在两种直接接触的介质（固体，液体，气体）Inconduction,energyistransferredthrough:

传导过程中，能量通过以下方式传递Movementoffreeelectron自由电子运动latticevibration点阵振动Convectionisthetransferofthermalenergybetweenasurfaceandamovingfluidhavingsometemperaturedifference对流发生在有温差的表面和运动流体间的传热ModesofHeatTransferConvectioncanbe:对流有如下两种方式：Free(natural)convectionForcedconvectionRadiationisthetransferofheatbetweentwosurfacesthathavenodirectcontact:幅射发生在两种没有直接接触的表面Energyisemittedthroughelectromagneticwaves

能量通过电磁波传递Allobjectattemperaturesabove0Kemitthermalradiation

所有物体大于0K均发生热幅射Mostofthethermalradiationtakesplaceintheinfrared(红外）wavelength(0.1to100micron)几乎所有热幅射发生在红外波长范围Therateofenergytransferdependsonsurfaceconditionsandtheviewbetweentheparticipatingbodies

能量传递率与表面条件及相关物体间的视角有关ConductionFourier’sLawofConduction:(1Dconduction)1D传导Q=-k.A.DT/DXor,Q=DT/RA,T1A,T2DXConductionWhere,Q=heattransferT=temperatureA=cross-sectionalareak=thermalconductivityoftheslabDX=slabthicknessR=DX/(kA)=ConductionresistanceTheslabisassumedtoconductinonedirectionFourier’sLawofConduction:(1Dconduction)Conductionk1k2k3L1L2L3T1T2Q=(T2-T1)/RR=R1+R2+R3R1=L1/(A.k1)R2=L2/(A.k2)R3=L3/(A.k3)AAFourier’sLawofConduction:(1Dconduction)ConductionFourier’sLawofConduction:(1Dconduction)A1A2A3T1T2Q=(T2-T1)/R1/R=1/R1+1/R2+1/R3R1=L/(A1.k1)R2=L/(A2.k2)R3=L/(A3.k3)Lk1k2k3ConvectionConvectionmaybefreeorforced.对流可以是自然和强迫Infreeconvectiontheflowisinducedbydensitydifferencescausedbytemperaturevariationswithinthefluid.自然对流是由于温度变化引起的流体内部密度不同产生的Inforcedconvectiontheflowisgeneratedbyexternalmeanssuchasfan,blower,pump,wind,etc.强迫对流则是由于外部方式造成的气流Flowsmayalsobeclassifiedasinternalflowsandexternalflows.气流也可以分为内流和外流Aninternalflowisflowthroughconfineddomainsuchasductsorchannels.内流是发生在一定的空间内，如管道等Anexternalflowisflowoversurfaceswhichcanbefullyorpartiallyunconfined.外流是全部或部分不在空间内的气流ConvectionFlowsmayalsobeclassifiedas气流可以被分为：laminar,or层流或Turbulent湍流Alaminarflowisahighlyorderedflowwherefluidparticlesmovealongidentifiablepaths层流是很规则的气流，气流的流线轨迹比较一致Inturbulentflowsfluidmotionishighlyirregularandischaracterizedbyrandom,three-dimensionalmotion

湍流很不规则，比较任意，三维运动Itinvolvesstrongmixingandmorevigorousheattransferflowisinherentlytime-dependentMostreallifeflowsareturbulentflows大多数流动是湍流Flowsverynearsurfaces(ofobjects)areusuallylaminarflows离开物体表面很近气流通常是层流ThisregioniswellwithintheboundarylayerItiscalledthelaminarsub-layerConvectionExternalFlow外流InternalFlow内流ConvectionLaminarFlow层流TurbulentFlow湍流Convection:Newton’sLawofCoolingFlow(atTemperature=Tf)A,h,TwQ=h.A.(Tw-Tf)=DT/Rwhere,Q=totalheatflowfromthepatchtotheair小块到空气的全部热量h=averageheattransfercoefficient平均传热系数A=areaofthepatch小块的面积Tw=averagetemperatureofthepatch小块的平均温度Tf=averagefluidtemperaturenearthepatch小块附近气流的平均温度R=thermalresistance=1/(hA)热阻Convection:TypicalhvaluesRepresentativehandRvalues典型的h和R值Convection:FactorsAffectinghTheheattransfercoefficient,h,dependsonmanyfactors:传热系数取决于很多因素Turbulentflowshavelargerheattransfercoefficientthanlaminarflows湍流比层流

h值大Ingeneral,forcedconvectionflowshavehigherheattransfercoefficientthannaturalconvectionflows强迫对流比自然对流h值大Liquidflowshavelargerheattransfercoefficientthangasflows液体比气体h值大Roughsurfaceshavelargerheattransfercoefficientthansmoothsurfaces(duetoflowturbulence)粗糙表面比光滑表面h值大Entry(undeveloped)flowshavelargerheattransfercoefficientthanfullydevelopedflows未展开气流比完全展开气流h值大Unsteadyflowstendtohavehigherheattransfercoefficientthansteadyones非稳态比稳态h值大PrintedCircuitBoardsPCBsPrintedCircuitBoardsComponent-side(top)viewSource:PixeldirectPrintedCircuitBoardsSolder-side(bottom)viewSource:PixeldirectPrintedCircuitBoardsAprintedcircuitboard(PCB)isgenerallyamulti-layeredboardmadeofadielectricmaterial(glass-reinforcedpolymerorFR4)andseverallayersofcopperplanesPCB是由FR4和几层铜板构成ItservestowiremountedICchipsthatwouldotherwiseneedthousandsofpoint-to-pointwireconnectionsAsingle-layerboardhascomponentsmountedononesideandcopper(conductor)patternontheother一层板的元件安装在一边，铜线（导热器）在另一边Thecopperpatternisestablishedbyphoto-etchingacopperfoilpastedoverFR4Adouble-layerboardhascopper(conductor)patternaswellascomponentsonbothsides两层板有铜，两边都有元件Amulti-layerboardismadeofseveraldouble-sidedboardswithinsulatinglayersinbetween

多层板由几个两层板组成，在层与层之间有绝缘层PrintedCircuitBoardsHeatandpressureisappliedtolaminatethelayersintoarigidstructurecalledthePCB加热和加压而制成一种坚硬的结构叫PCBMulti-layerPCBsgenerallyhave4-10layersofcopper多层PCBs通常有4-10层铜线Toestablishelectricalconnectionbetweenthedifferentcomponentsandthecopperlayers,vias(smallholeslinedwithmetalplates)aredrilledthroughthethicknessofthePCB

为了使不同元件和铜线层建立连接，通过在PCB厚度上打孔（vias）TheviasmaycutthroughtheentirethicknessofthePCBorconnectafewlayersonly

Vias可能穿透整个板或只连接几层Inamulti-layerboard,someofthecopperlayersareusedtoprovidegroundandpowersupplyvoltages,whiletheremaininglayersareusedtointerconnecttheICchips

多层板中，有些铜线层会用来提供基础和电流电压，而其它的层用来提供ICchips间的连接PrintedCircuitBoardsLaminatesinamulti-layerPCBPrintedCircuitBoardsTheareacoverageofthecopperlayerscanvarybetween10%to90%铜线层的含量通常在10%到90%Thethicknessofonelayerofcopperisabout35micronor,asiscommonlyreportedintheindustry,itcontains1ozofcopperpersquarefoot一层铜的厚度约在35微米或每平方英尺含1oz的铜ComponentsmaybemountedonaPCBusing元件可以通过以下方式安装到PCB上Though-HoleTechnology(THT),or穿孔型Surface-MountTechnology(SMT)表面安装型InTHT,thelegs(pins)ofthecomponentspassthroughholesandaresolderedattheoppositesideofthePCBTHT方法，pins通过孔到PCB另一面焊接InSMT,thechipsaresolderedtothePCBandconnectedtotheconductorlayeronthesamesideofthePCBSMT方法，chips被焊接到PCB同一侧PrintedCircuitBoardsTheconductivityofpureFR4is0.25W/mK纯FR4的导热率为0.25Theconductivityofpurecopperis388W/mK铜的导热率为388Fromthermalmodelingpointofview,aPCBbetreatedasahomogeneousmaterialwithnon-isotropic(direction-dependent)conductivity从热模型的角度来看，PCB应作为一种非正交导热率的材料ThePCBmodelmaywillcontainin-planeandnormal-to-planeconductivityvaluesPCB应有面内和法向导热值Thein-planeconductivityismuchlargerthanthenormal-to-planeconductivity面内值要比法向大得多Thein-planeconductivityincreaseswiththenumberofcopperlayersofthePCB面内导热率随着铜线层的增加而增加ThenormalconductivityaPCBisnearlyconstantatabout0.3W/mK法向导热率通常在0.3PrintedCircuitBoardsThein-planeandnormal-to-planeconductivityvaluesmaybecalculatedasfollows:

面内导热率可采用下面公式计算： kin-plane=S(kiti)/(Sti) knormal=Sti/S(ti/ki) ki=fi*kcu

where, fi=fractionalcoverageofcopper k=conductivityofalayer(W/mK) t=thicknessofalayer(m)Whenhigheraccuracyisdesired,aPCBmaybemodeledusingmultipleplates:如果还希望得到更准确的数值，PCB应采用多层板来建模AconductingthickplatefortheFR4,andseveralconductingthinplatesforthecopperlayersPrintedCircuitBoardsExample例如：Numberofculayers=8Thicknessof1layerofcopper=1oz=3.5e-5mThicknessof1layerofFR4=1.453e-4mConductivityofcopper=388W/mKConductivityofFR4=0.25W/mKIn-planeconductivity: Kp=((8*388*3.5e-5)+(9*0.25*1.453e-4))/1.588e-3 =68.6W/mKNormalconductivity: Kn=1.588e-3/((8*3.5e-5/388)+(9*1.453e-4/0.25)) =0.303W/mKPrintedCircuitBoardsPCBModelingAPCBmaybemodeledusingoneoftwoways:PCB可以采用如下的两种方法建模：DetailedmodelCompactmodelTheDetailedPCBModelincludes:详细PCB包括：AnFR4plateorblock,andCopperlayersmodeledasconductingthinplatesTheCompactPCBModelincludes:简化PCB模型包括：ANon-isotropicplateIn-planeconductivityismuchhigherthanthenormalconductivityThecopperlayersarenotmodeledseparatelyPCBModelingIcepakmenuforPCBcreationPCBModelingCompactPCBModelDetailedPCBModelK(in-plane)=27W/mKK(normal)=0.34W/mKFR4(K=0.3W/mK)CopperlayersNon-IsotropicmaterialICPackagesICPackagesIC封装ICPackagesICPackagesAnICpackageisthehousingthatprotectsthechipfrom:

IC封装是为了保护的空间Environmentalstresssuchashumidityandpollution环境压力如湿度，污染Mechanicalstresssuchascrackingandoverheating机械压力如破裂，过热Electricaldischargeduringhandling操作过程中的放电TheICpackagemustalsoprovide:IC封装必须提供：Interfacefortesting用于测试的接触面Electricalinterconnectiontothenextlevelofpackaging与PCB连接的电子连接面AnICpackagemustsatisfytheaboverequirementswhilemeetingotherobjectssuchascost,qualityandreliabilityIC封装还应满足其它要求如成本，质量和可靠性Itisthefirstlevelofelectronicpackaging它是电子封装的第一级ThesecondlevelbeingPackage-PCBassembly第二级是封装-PCB装配ThethirdlevelisPCBassemblytotheBackplane第三级是PCB与底板装配LevelsofPackagingSystem-levelAssemblyBackplaneAssemblyICPackagePCBAssemblyChipsICPackagesPackagesmaybeclassified(bymountingmethod)as:

封装可以分为（按安装方法）：Through-holetype(THT)穿孔型Surfacemounttype(SMT)表面安装型Specialpackages特殊类型THTpackageshavepinsthatareinsertedintoholesdrilledacrossthethicknessofthePCBTHT封装的pins穿过PCB上的孔TheyareusedinpackagewhereboardspaceisnotpremiumExamplesareDIP,PGA,etc.SMTpackageshaveflatstructurewiththeleadpinssoldereddirectlyintotheconductorpatternonthesurfaceofthePCBSMT封装的pins直接焊接在PCB的表面TheyareusedinhighpindensitypackagesExamplesareQFP,QFJ,etc.THTPackageExamplesZIP(ZigzagIn-linePackage)DIP(DualIn-linePackage)SMTPackageExamplesQFP(QuadFlatPackage)SSOP(ShrinkSmallOutlinePackage)ICPackagesICPackagesSpecialpackagesarepackagessuchas:

特殊类型封装如：Chip-on-board(COP)packageswherethechipismountedandsealedonthePCBCOP封装被安装并密封在PCB上TapeCarrierPackages(TCP)带载封装Memorymodules记忆模块Powerdissipationperchipisafunctionof:

每种芯片耗散功率是下列参数的函数：Frequency,f频率Capacitance,C电容Voltage,V电压Gatecount(I/Ocount)门数Morespecifically:即：

Power=F(f,C,V2,Gatecount)ICPackagesLogic(ASIC)chipshavemoregates(andhenceproducemorepower)thanmemorychips

逻辑芯片比记忆芯片有更多的门Thus,fromcoolingperspective,logicchipsaremoredifficulttocoolthanmemorychips

因此，从散热的观点来看，逻辑芯片比记忆芯片要难ExamplesofICPackagesPlasticBallGridArray(PBGA)LowConductingtop(~1W/m/K)顶部的导热率低(~1

W/m/K)PCBtypeMaterialSubstratePCB材料型底部Smalldie(1/3ofpackagesize)小尺寸dieInterconnectisatthedietop,andsoisthepowerdie顶部与热源内部相连ExamplesofICPackagesTapeBallGridArray(TBGA)HighConductingTop(copper)顶部的导热率高TapeSubstrate(thinnerthanPBGA)Substrate比PBGA薄Dieis1/3ofPackageInterconnectisatthediebottom,andsoisthepowerExamplesofICPackagesFinePitchBallGridArray(FPBGA)LowConductingtop(~1W/m/K)顶部的导热率低(~1W/m/K)PCBtypeMaterialSubstrateChipScalePackage(CSP)(dieisabout70%ofpackagesize)Interconnectisatthedietop,andsoisthepowerModelisexactlythesameasPBGA模型与PBGA相似ExamplesofICPackagesFlipChipCeramicBallGridArray(Flipchip-CBGA)Exposeddie,optionalheatspreader,NowireBonds

外露的die,可选的散热板，无线CeramicSubstrate(K~15W/m/K)陶瓷SubstrateInterconnectatdiebottom;Interconnectjunctionsisattachedtosolderbumps,whichinturnconnectssignaltracesModelisexactlythesameasPBGA模型与PBGA相似ExamplesofICPackagesPlasticQuadFlatPack(PQFP)LowConductingovermolding(~1W/m/K)顶部的导热率低Dieisabout1/3ofpackage;NosubstrateInterconnectisatthedietop,andsoisthepowerConnectsperipherallytoPCBcircuitryviagoldwireleadsExamplesofICPackagesABGA(AdvancedBGA)PackagewithCeramicSubstrate(CBGA)ConductionPathsTypesofPackageModelsDetailedModels详细的模型Detailsofthepackageareincludedinthemodel,suchassolderballs,leads,die,encapsulation,substrate,etc.UsedforPackageLevelModelingandmeasurementvalidationCompact(Semi-Detailed)Models简化的模型(半详细)ThemaincomponentsaremodeledusingThickorThinconductingplates,componentssuchasthedie,solderballs,substrate,etc.ThismodelisusedtoreducethemeshcountThereissomedropinaccuracyasaresultGoodforBoardandSub-systemLevelModelingTypesofPackageModelsNetwork(Resistance)Models网络模型

PackagemodeledusingresistancenetworkThenetworkcanbetwo-resistornetwork,Starnetwork,Shuntnetwork,etc.TheusermustsupplytheresistanceValuesforthenetworkTheresistancevaluesmaybeobtainedfrommanufacturers,experiments,ordetailedpackagemodelsDetailedPackageModelMoldSolderBallsDieSubstrateWireBondCuTraceDiePadSemi-DetailedPackageModelContactResistanceDiePadMoldSolderBallsDetailedModelSemi-detailedModelNetworkPackageModelTwo-ResistorNetworkModelSix-Resistor(Star)NetworkModel393922Rjc=3Rjb=9Rjc=3Rjb=9Rjs=2DefinitionofPackageResistances

qjc=(Tdie–Tcase)/QcaseTdie=dietemperatureTcase=casetemperatureQcase=heatdissipatedthroughthecase

qjb

=(Tdie–Tbot)/QboardTbot=temperatureofpackagebottomQboard=heatdissipatedfromthepackagebottomtotheboardqja

=(Tdie–Tamb)/QcaseTamb=ambienttemperatureQdie=totalheatdissipatedfromthepackageFactorsAffectingChipResistancesqjadependson:与下列因素有关：DiepowerDie功耗Chipsize芯片大小Natureofconductionpaths(leadframes,etc.)传导途径Airvelocity气流速度PCBtypeandpopulationPCB类型和数量qjadecreasesas:随下列因素而降低chipsizeincreases芯片尺寸增大Airvelocityincreases气流速度增加conductionpathsimprove传导途径改善Theresistancesmeasuredforasinglepackageonaboardareusuallylowerthanthoseobtainedonapopulatedboard,andmayonlyserveasalowerbound板上单个封装测量的阻尼比很多封装在板上测量的结果要低FactorsAffectingChipResistancesTypicalValuesof

qja

Source:NECPackagesTypicalValuesof

qja

Source:NECPackagesTypicalValuesof

qjaTheeffectofboardconfigurationonqja

Source:MotorolaDetailedvsNetworkModelsTcase~73-88CTcase~80CDetailedModelNetworkModelRjc=20Rjb=40Airvelocity=1m/s(Rja=44)(Rja=40)Exercise1:PBGAModelExercise1:练习1：PBGA模型Exercise1:PBGADetailedModel1.CreateaCabinet生成一个cabinetUnderModel/Cabinet,createacabinetwiththefollowingspecifications:(Alldimensionsinm)XS=-0.0375 XE=0.0375YS=-0.02 YE=0.0075ZS=-0.0375 ZE=0.0375Exercise1:PBGADetailedModel2.CreateanInletOpening生成一个入口UnderModel/Openings,createaninletopeningwiththefollowingdimensionsandvelocityspecification:Plane: X-YXS=-0.0375 XE=0.0375YS=-0.02 YE=0.0075ZS=-0.0375Zvelocity=0.3m/sInletOpeningExercise1:PBGADetailedModelOutletOpening3.CreateanOutletOpening生成一个出口UnderModel/Openings,createanoutletopeningwiththefollowingdimensions:XS=-0.0375 XE=0.0375YS=-0.02 YE=0.0075ZS=0.0375 Exercise1:PBGADetailedModel4.PCBMaterial材料UnderModel/Materials/Solid,createaPCBmaterialwiththefollowingspecifications:name: pcb-materialSub-type:otherConductivity:1.0W/m-KToggleonOrthotropic,

andassign:X=25W/m-K Y=0.3W/m-KZ=25W/m-KExercise1:PBGADetailedModel5.CreateaPlate生成一块板UnderModel/Plates,createaplateusingthefollowingspecifications:(Alldimensionsinm)

Name: pcbPlane: X-ZXS=-0.0375 XE=0.0375YS=-0.009 ZS=-0.0375 ZE=0.0375Thermalmodel: ConductingthickThickness=0.0015mSolidmaterial: pcb-materialPlatecreationmenuExercise1:PBGADetailedModel6.CreateadetailedPBGA生成一个详细的PBGAUnderModel/Macros/Packages,createaPBGApackage:Takeallthedefaultspecificationsasshowninthenextfourfigureswithoneexception:ChangethemodeltypefromCompacttoDetailed,thatis,underDimensions: Modeltype:Detailed(Seefiguresinthenextfourpages)Exercise1:PBGADetailedModelPBGAPackagecreationmenu:DimensionsExercise1:PBGADetailedModelPBGAPackagecreationmenu:SubstrateExercise1:PBGADetailedModelPBGAPackagecreationmenu:SolderBallsExercise1:PBGADetailedModelPBGAPackagecreationmenu:Die&MoldExercise1:PBGADetailedModel7.SpecifyMeshControls生成网格GotoModel/Meshandspecifythefollowingmeshcontrols:MaxX=0.007MaxY=0.003MaxZ=0.007Minelementsinfluidgap=2Minelementsonsolidedge=1MaxO-gridheight=3Exercise1:PBGADetailedModel8.GetaSolution求解1.GotoSolution/SolveandclickAccept2.Waituntilsolutionisfinished3.GotoPostandclickObjectfaceandselect:-Objecttype:group-Objectname:pbga.1

4.ToggleonContours5.ClickCreateExercise1:PBGANetworkModel9.CreateaPBGANetworkModel生成一个PBGA网络模型1.MakeacopyofthePBGAdetailedmodelandnameitpbga-network2.GotoFile/Openandloadthenewmodel3.UnderModel/Groups,highlightthenamepbga.1andclickDeleteall;thisdeletesallthecomponentsofthedetailedPBGAmodelExercise1:PBGANetworkModel10.CreateaPBGANetworkBlock生成PBGA块2.UnderModel/block,createaNetworkblockwiththefollowingspecifications:(Dimensionsinm)XS=-0.0075 XE=0.0075YS=-0.0075 YE=-0.0059ZS=-0.0075 ZE=0.0075Rjc=12C/W Rjb=25C/WJunctionpower=1WExercise1:PBGANetworkModel11.SpecifyMeshControls定义网格GotoModel/Meshandspecifythefollowingmeshcontrols:MaxX=0.007MaxY=0.003MaxZ=0.007Minelementsinfluidgap=2Minelementsonsolidedge=1MaxO-gridheight=3Maxinitheight=0.001Exercise1:PBGANetworkModel12.GetaSolution求解1.GotoSolution/SolveandclickAccept2.Waituntilsolutionisfinished3.GotoPostandclickObjectfaceandselect:-Objecttype:block-Objectname:Network-PBGA

4.ToggleonContours5.ClickCreateHeatSinksHeatSinks散热器HeatSinksHeatSinksHeatsinksareusedtoenhanceheattransferfromacomponentbyextendingthesurfaceareaofheattransfer散热器通过扩大散热面积提高传热效果Newton’slawofcooling: Q=h.A.(Tw-Tf)Where,Q=totalheattransferfromthecomponentA=surfaceareaofthecomponentTw=surfacetemperatureofthecomponentTf=surroundingfluidtemperatureh=heattransfercoefficientTheaboveequationstatesthat,foragivenQ,handTf,thelargerthesurfacearea(A),thesmallerthesurfacetemperature(Tw)willbe上述公式说明，对于一个给定的Q，h和Tf,表面积越大，表面温度越低HeatSinksThemostcommontypeofheatsinkisthefinnedheatsink最常用的散热器是翅片散热器Finsareformedbyextrusion,molding,machining,orAttachedbythermallyconductivematerialsThemostcommonheatsinkmaterialsusedarealuminumandcopper最常用的散热器材料为铝或铜Theyareoflowcost,andEasytomachinematerialsThethermalcoefficientofexpansion(TCE)forthesematerialsishigh这些材料的热膨胀系数高Hence,theycannotberigidlyattachedtolowTCEpackagessuchasalumina;Forsuchapplications,wemayuseheatsinksmadeoflowTCE,orbondthemusingthermallyflexibleattachmentmaterials

因此，它们不能坚固地贴在低TCE封装上；这种情况，我们必须使用低TCE的散热器，或结合可变形附着材料使用TypesofHeatSinksTypesofHeatSinksavailable:现有的散热器种类：Stampings冲压Extrusions拉伸Bonded/Fabricated粘接Folded折叠Liquid-cooledcoldplates液体冷板Casting

铸造StampingHeatSinks:冲压散热器aremadeofcopperoraluminumsheetmetallowcost,highvolumesolutionforlowpowerapplicationsExtrusionHeatSinks:拉伸散热器maybeusedforlargewattageloadscanbelongitudinal,cross-cut,orserratedtypesLimitedbyheight-to-gapratioandfinthicknessthatcanbeachievedbymachiningTypesofHeatSinksBonded/FabricatedHeatSinks:粘接散热器TheyarehighperformanceheatsinksNolimitationonheight-to-gapratioorfinthicknessFolded-FinHeatSinks:折叠-fin散热器ThincorrugatedsheetmetalbondedorbrazedtobasemetalArelowprofileheatsinksLiquid-CooledColdPlates:液体冷板TubesinblockormilledpassagesUsedforheatloadsof500to30,000W/m2KCastingHeatSinks:铸造散热器Sand,lostcoreanddiecastingwith