产品的热设计Thermalintroduction课件

IntroductionofThermalGGT/RE–EnvironmentTestTeamPrimaryMechanicofHeatTransfer

Thermalenergytransport:causebytemperaturedifference,highT->lowTConductionHeattransferringbysolidmediumConvectionTransferringenergybetweensolidsurfaceandfluidMasstransportNatural(free)convectionForcedconvectionRadiationHeattransferringbyelectromagneticwavesConductionFourier’sLaw Q=-KAΔT/ΔL Q:heattransferrate A:cross-sectionalareaofheatfluxΔT/ΔL:temperaturegradientK:thermalconductivity(W/mk) Ex.Al=230 Cu=380 Mylar=1.8RadiationQa=εσAF1-2(Ts4–Ta4)Qa:radiationheattransferrateε:emissivity,0≦

ε

≦1σ:Stefan-BoltzmannconstantA:surfaceareaF1-2:viewfactorTs:temperatureofbodysTa:temperatureofbodyaThermalResistanceR=V/I V:voltage=ΔT:temperaturedifference I:current=Q:heatConduction Rk=ΔL/KAkConvection Rs=1/hcAsRadiation Ra=(Ts–Ta)/εσAF1-2(Ts4–Ta4)BasicConceptsforNBThermalDesign

ThermalDesignTargetThermaldesignmustmeetthermalspec.ofCPU,allkeycomponents(HDD,FDD,CD-ROM,PCMCIA…),andallICchips(Chipset,VGA,RAM,PCMCIA…),andallICchips(Chipset,VGA,RAM,Audio…)ineachuserconditions

ThermalResistanceΘj-a=(Tj–Ta)/Pcpu

Θj-a:CPUjunctiontoambientthermalresistance Tj:CPUjunctiontemperature Ta:ambienttemperature Pcpu:CPUpowerBasicConceptsforNBThermalDesign

ThermalSolutions Passivethermalsolution Activethermalsolution HybridthermalsolutionRHE RemoteHeatExchangerBasicConceptsforNBThermalDesignCharacteristicofagoodpassivecomponents SpreaderplateconnectedtoCPUshouldbeaslargeaspossible TemperaturevariationonspreaderplateshouldbeminimalCharacteristicofagoodactivecomponent Airinletandoutletshouldbeclearlydefined LengthofairpassagethroughNBshouldbesmalltokeeppressuredroplow,flowratehigh Possiblereducenoiselevelofthefan DesignmustbecapableofventingaportionofhotairfromNBinside

ImportantComponentsForThermalDesign

HeatSinkHeatPipeFanTIM(ThermalInterfaceMaterial)Combinationofaforementionedcomponents

HeatPipeBasicconfigurationandcharacteristicBasicspecificationMaterial:copperWorkingfluid:purewaterStandardworkingtemperature:0~100℃Size:ψ3,ψ4,ψ5,ψ6,ψ8TypicalheatpipewickstructuresFiber,mesh,groove,powderTypicalmodificationofheatpipeFlatteningBendingHeatPlateFanStructureRotator:magneticblade,shaftStator:bearing,wire,stainlessplateControlcircuitTheoryTypeAxialfanBlowerfanSelectionTotalcoolingrequirementQ=Cp*m*ΔT=ρ*Cp*CFM*ΔTTotalsystemresistance/systemcharacteristiccurveSystemoperatingpointFanParallelandseriesoperationAcousticalnoiselevel(dB)ToachievelownoiseshouldconsiderSystemimpedanceFlowdisturbanceFanspeedandsizeTemperatureriseVibrationVoltagevariationDesignconsiderationsThermalDesignProcedureClarifyThermalSpecificationDesignThermalSolutionAnalyticApproachEvaluateSolutionPerformanceNumerical

ApproachExperimentApproachVerifyDesignThermalSolutionEvaluateheatgenerationAllowablethermalresistanceAllowabledesignspaceEvaluateChassisheatdissipationEvaluateheatexchangeareaEvaluatefanflowratePassFailInspectStructure.Productionmethod.Cost…RecommendThermalSolutionThermalTestinWorkingSampleVerifyOverallSystemMeetingThermalSpecificationThermalDesignOK!ExamineandModifyThermalSolutionPassFailThermalDesignGuidesDesignguideforthermal(Ver.0.2)

fiberMesh細絲(銅絲)螺旋彈片銅网groove直接加工而成Powder類型:金屬粉末燒結在HeatPipe內壁,形成毛細結構CFM(ft3/min)StaticpressureSystemresistancecurveFancurveSystemoperatingpointThermalModuleReservespaceforthermalmodule(Intelrecommendation)Coppermine: 70*50*11.5mmTualatin: 75*55*11.5mmNorthwood: 85*60*19mmItshouldreserveagapbetweenthermalmoduleandtopcover(keyboardcover)2.FanFaninletconstraints:gap3~5mmisneeded. 3mm~80%performance 4mm~90%performance 5mm~100%performanceConfigurationofairinlet&outletventscanmakedramaticallyflowresistance;thereforehighopenrateisbetter.

2.FanDon’tplaceblocks(largeICsorconnector)nearorbelowthefantoaffectairflowinducedintofan.Itisbetterforfixingfanbyrubberinsteadofmetalscrewstoavoidvibration.2.FanThefanspacedesignhassomerestrictions.Forefficiencyandacoustic,thegapbetweenfinsandfanbladeshouldkeepadistanceofL=5~10mm.ThedistanceWisbettertokeepaslargeaspossibleforgoodefficiency.Fanbladeshouldclosetofantongueforbetterefficiency.3.PCMCIACardDon’tplacePCMCIAonlowersideofM/B,nearhotterICs,andstackedupkeycomponents(HDD,CD-ROM,DVD,FDD…).

IfitneedstoplacePCMCIAnearheatsource,itisnecessarytoinduceairflowtocoolit.(Ex.ForJ2I++,L1R,itisremovedmetalplateonPCMCIAslotandmakesholesabovePCMCIAifthereisanAlplateuponit.Bythisway,aircanflowthroughthisareatocoolPCMCIAcard.)3.PCMCIACardDuetoaforementionedsolution,PCMCIAshouldplacenearfaninordertoinduceairflowtocool.4.KeyComponentsBecauseHDD,CD-ROM,FDDthermalSPCEislow,thesekeycomponentsneedtobeplacedincolderregion.(AvoidplacingtheminthemiddleofthesystemanduponM/BwithhotICs,andstackingupeachother).

It’sbettertoplaceFDDalone,nottoputon/beneathCD-ROMorHDD.5.Palm-RestandGlidPadItshouldavoidplacinghotcomponentsandICsbelowpalm-restandglidpad.Itshouldreserveagaptomakeathermalresistancebetweenpalm-restandthehotcomponentsortoaddametalplateforspreadingheat.6.LCDInverterItshouldreserveagapbetweenInverterandLCDcovertomakeathermalresistanceortoaddametalplateforspreadingheat.7.BottomcaseandDimmDoorItshouldreserveagapbetweenICchipsandbottomcase(gap>3mmisbetter).ItmighthavealargeAl-plateonbottomcaseforspreadingheat.M/BhasaholebelowfaninordertoinduceairflowunderM/B.It’sbettertoplacehotterchipsonuppersideofM/B.ItshouldreserveagapbetweenMemorychipsanddimmdoor(gape>1.5mmisbetter).8.M/BLayoutIfthere’sthermalissueofICs,itshouldreservespaceforthermalsolutions(Ex.Don’tplacehighercomponentsbesidetheseICs,soitcouldputmetalplateonICsinfuture)Don’tplacelowtemperaturespecICsandcomponentsnearhotterregionorhightemperaturespecICsandcomponents.

9.OthersIt’sbettertousethethinnerorphasechangeTIM(thermalinterfacematerial)Ex.28WCPU(phasechange)Powerstrate0.08mm 75℃(phasechange)T-pcm0.25mm

83℃T-pcm0.50mm 86℃(phasechangewithAl)

T-mate

0.50mm 83℃(non-phasechange)Tx0.25mm 90℃

Tx 0.5mm 96℃9.OthersHeatpipesonthermalmodulehavesomerestrictionsThethicknessshouldn’tbelessthan2mmwhenbemadeflat.Thecurveradiusshouldbelargerthantr