产品的热设计Thermalintroduction课件学习.ppt

1、Introduction of ThermalGGT/RE Environment Test TeamPrimary Mechanic of Heat Transfer Thermal energy transport:cause by temperature difference,high T-low T ConductionHeat transferring by solid mediumConvectionTransferring energy between solid surface and fluidMass transportNatural(free)convectionForc

2、ed convectionRadiationHeat transferring by electromagnetic waves Conduction Fouriers LawQ=-KA T/LQ:heat transfer rateA:cross-sectional area of heat flux T/L:temperature gradient K:thermal conductivity(W/mk)Ex.Al=230 Cu=380 Mylar=1.8 Convection Newtonian cooling LawQc=hc As(Ts Ta)Qc:convection heat t

3、ransfer rateAs:surface areaTs:surface temperature of solidTa:tmperature of ambient hc:heat transfer coefficient,f(flow type,body geometry,physical property,temperature,velocity,viscosity)Natural convection&Forced convctionhc of air,natural convection:0.00150.015 W/in2 forced convection:0.0150.15 W/i

4、n2 Thermal Resistance R=V/IV:voltage=T:temperature differenceI:current=Q:heatConductionRk=L/KAkConvection Rs=1/hcAsRadiationRa=(Ts Ta)/AF1-2(Ts4 Ta4)Basic Concepts for NB Thermal Design Thermal Design TargetThermal design must meet thermal spec.of CPU,all key components(HDD,FDD,CD-ROM,PCMCIA),and al

5、l IC chips(Chipset,VGA,RAM,PCMCIA),and all IC chips(Chipset,VGA,RAM,Audio)in each user conditions Thermal Resistancej-a=(Tj Ta)/Pcpu j-a:CPU junction to ambient thermal resistanceTj:CPU junction temperatureTa:ambient temperaturePcpu:CPU power Basic Concepts for NB Thermal Design System Thermal Coupl

6、ing effect j-a=(Tj Ta Tsys)/PcpuTsys:system temperature=Psys*=Pi*i,(i:DRAM,Chipset,HDD,FDD,CD-ROM)R:thermal coupling factor between Pcpu and PsysTj:CPU spec.for Intel:100Ta:OEM spec.,35j-a,Tsys:OEM design dependent,Tsys=1015 Basic Concepts for NB Thermal Design Thermal SolutionsPassive thermal solut

7、ionActive thermal solutionHybrid thermal solutionRHERemote Heat ExchangerBasic Concepts for NB Thermal DesignCharacteristic of a good passive componentsSpreader plate connected to CPU should be as large as possibleTemperature variation on spreader plate should be minimalCharacteristic of a good acti

8、ve componentAir inlet and outlet should be clearly definedLength of air passage through NB should be small to keep pressure drop low,flow rate highPossible reduce noise level of the fan1.Design must be capable of venting a portion of hot air from NB inside Important Components For Thermal Design Hea

9、t Sink Heat Pipe Fan TIM(Thermal Interface Material)Combination of aforementioned components Heat Sink MaterialMaterial :A1050 A6063 ADC12 C1100K(W/mk):230 210 192 384Specific gravity:2.71 2.69 2.70 8.92ProductionDie-castingExtrudedQ=-KAT/LFin,Q=hATDie-casting,extrusion,folder,stack,soldering fins H

10、eat Pipe Basic configuration and characteristicBasic specificationMaterial:copperWorking fluid:pure waterStandard working temperature:0100Size:3,4,5,6,8Typical heat pipe wick structuresFiber,mesh,groove,powderTypical modification of heat pipeFlatteningBendingHeat Plate Fan StructureRotator:magnetic

11、blade,shaftStator:bearing,wire,stainless plateControl circuitTheoryTypeAxial fanBlower fanSelectionTotal cooling requirementQ=Cp*m*T=*Cp*CFM*TTotal system resistance/system characteristic curveSystem operating pointFan Parallel and series operationAcoustical noise level(dB)To achieve low noise shoul

12、d considerSystem impedanceFlow disturbanceFan speed and sizeTemperature riseVibrationVoltage variationDesign considerations TIM Thermal Interface MaterialTo reduce contact thermal resistance between CPU die and thermal moduleImportant of TIMMaterialVarious material:silicon-base,carbonNon-phase chang

13、ePhase change Pressure effectPressure spec.on CPU spec.100psiThermal Design ProcedureAnalytic ApproachEvaluate Solution PerformanceNumerical ApproachExperiment ApproachVerifyEvaluate heat generationAllowable thermal resistanceAllowable design spaceEvaluate Chassis heat dissipationEvaluate heat excha

14、nge areaEvaluate fan flow ratePassFailInspect Structure.Production method.CostRecommend Thermal SolutionThermal Test in Working SampleVerify Overall SystemMeeting Thermal SpecificationThermal Design OK!Examine and ModifyThermal SolutionPassFailThermal Design GuidesDesign guide for thermal (Ver.0.2)T

15、hank You!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Heat Pipe內壁,形成毛細結構NNNNSSSS無刷馬達轉動原理無刷馬達轉動原理有Hall IC 感應其磁鐵N.S.極,經由電路控制其線圈之導通產生內部激磁使轉子部旋轉CFM(ft3/min)Static pressureSystem resistance curveFan curveSystem operating pointThermal Module wReserve space for thermal module(Intel recommendation)Copp

16、ermine:70*50*11.5mmTualatin:75*55*11.5mmNorthwood:85*60*19mm wIt should reserve a gap between thermal module and top cover(keyboard cover)1.Thermal ModulewThe gap between thermal module exit and NB case vent should be sealed well so the hot air couldnt flow back to system.If leave an open gap along

17、air flow path,it will affect thermal efficiency and acoustic noise.1.Thermal ModulewThe thermal module and CPU should contact well.n The max pressure of the thermal module on CPU is 100psi.Within SPEC,efficiency of thermal module increases with pressure.n Its better to fix module on M/B by four scre

18、ws(avoiding three screws)and spring design.2.Fan wFan inlet constraints:gap 35mm is needed.3mm 80%performance4mm 90%performance5mm 100%performancewConfiguration of air inlet&outlet vents can make dramatically flow resistance;therefore high open rate is better.2.FanwDont place blocks(large ICs or con

19、nector)near or below the fan to affect airflow induced into fan.wIt is better for fixing fan by rubber instead of metal screws to avoid vibration.2.FanwThe fan space design has some restrictions.wFor efficiency and acoustic,the gap between fins and fan blade should keep a distance of L=5 10 mm.wThe

20、distance W is better to keep as large as possible for good efficiency.wFan blade should close to fan tongue for better efficiency.3.PCMCIA Card wDont place PCMCIA on lower side of M/B,near hotter ICs,and stacked up key components(HDD,CD-ROM,DVD,FDD).wIf it needs to place PCMCIA near heat source,it i

21、s necessary to induce airflow to cool it.(Ex.For J2I+,L1R,it is removed metal plate on PCMCIA slot and makes holes above PCMCIA if there is an Al plate upon it.By this way,air can flow through this area to cool PCMCIA card.)3.PCMCIA CardwDue to aforementioned solution,PCMCIA should place near fan in

22、 order to induce airflow to cool.4.Key Components wBecause HDD,CD-ROM,FDD thermal SPCE is low,these key components need to be placed in colder region.(Avoid placing them in the middle of the system and upon M/B with hot ICs,and stacking up each other).wIts better to place FDD alone,not to put on/ben

23、eath CD-ROM or HDD.5.Palm-Rest and Glid Pad wIt should avoid placing hot components and ICs below palm-rest and glid pad.wIt should reserve a gap to make a thermal resistance between palm-rest and the hot components or to add a metal plate for spreading heat.6.LCD Inverter It should reserve a gap be

24、tween Inverter and LCD cover to make a thermal resistance or to add a metal plate for spreading heat.7.Bottom case and Dimm Door wIt should reserve a gap between IC chips and bottom case(gap 3mm is better).w It might have a large Al-plate on bottom case for spreading heat.w M/B has a hole below fan

25、in order to induce airflow under M/B.wIts better to place hotter chips on upper side of M/B.wIt should reserve a gap between Memory chips and dimm door(gape 1.5mm is better).8.M/B Layout wIf theres thermal issue of ICs,it should reserve space for thermal solutions(Ex.Dont place higher components bes

26、ide these ICs,so it could put metal plate on ICs in future)wDont place low temperature spec ICs and components near hotter region or high temperature spec ICs and components.9.Others wIts better to use the thinner or phase change TIM(thermal interface material)Ex.28W CPU(phase change)Powerstrate 0.0

27、8mm 75 (phase change)T-pcm 0.25mm 83 T-pcm 0.50mm 86 (phase change with Al)T-mate 0.50mm 83 (non-phase change)Tx 0.25mm 90 Tx 0.5mm 969.OtherswHeat pipes on thermal module have some restrictions wThe thickness shouldnt be less than 2mm when be made flat.wThe curve radius should be larger than triple

28、 diameter at least when be bended.wIt might need some holes on bottom case and sidewall of NB in order to induce airflow to dissipate heat.35mmAir flowFan 3mm 80%performance4mm 90%performance5mm 100%performanceFan BlocksBad designLWTongue該縫隙越小該縫隙越小Fan 效效率越高率越高,但但Noise 也會隨之上升也會隨之上升L:太大太大,Fan效率效率下降下降;

29、太小太小,噪音上升噪音上升.W:作為風道作為風道,盡量大盡量大Single fanDouble fanParallel CFMPressurePressureCFMSingle fanDouble fanSeriesTIM:thermal interface material考慮將散熱器固定於發熱器件的方法時,重要的是要使二者之間界面熱傳到處效率最大.也應考慮其他要求,如介電特性,電導性,附著強度和再次安裝的可能性.發熱組件和散熱器之間界面的熱傳輸效率取決於空氣殘留,填充物類型和黏合曾的厚度等參數.方 法優 點缺 點機械安裝有助於散熱;可即時安裝空氣間隙導致較差的傳導率;緊固件導致壓應力帶矽樹脂的機械安裝(有/無雲母墊片)好的導熱率流程控制困難;由移植和灰塵造成的污染會引起接觸不良帶可壓縮墊片和墊料的機械安裝較好的導熱率;無移植問題嚴重的扭矩變化會導致難以防止緊固件鬆動帶還氧樹脂黏合劑的黏合良好的導熱率;壓力均衡(可避免鬆動);無移植問題要求混合;罐裝壽命有限;熱固性不允許在線安裝相變化材料良好的導熱率重複性使用差