产品的热设计(Thermal_introduction)剖析课件.ppt

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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) convecti

2、onForced 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 T

3、a)Qc: convection heat transfer 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

4、W/in2 forced convection: 0.0150.15 W/in2 Radiation Qa = AF1-2( Ts4 Ta4)Qa: radiation heat transfer rate: emissivity, 0 1: Stefan-Boltzmann constantA: surface areaF1-2: view factorTs: temperature of body sTa: temperature of body aThermal Resistance R = V / IV: voltage = T: temperature differenceI: cu

5、rrent = 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 all IC chips (Chipset, VGA, RAM, PCMCIA), and

6、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 Coupling effect j-a = (Tj Ta T

7、sys) / 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 sol

8、utionActive 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 ac

9、tive 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 fanDesign must be capable of venting a portion of hot air from NB inside Important Components For Thermal Design He

10、at 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,

11、 soldering fins Heat 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 Fa

12、n StructureRotator: magnetic 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 operationAcou

13、stical noise level (dB)To achieve low noise should considerSystem impedanceFlow disturbanceFan speed and sizeTemperature riseVibrationVoltage variationDesign considerations TIM Thermal Interface MaterialTo reduce contact thermal resistance between CPU die and thermal moduleImportant of TIMMaterialVa

14、rious material: silicon-base, carbonNon-phase changePhase change Pressure effectPressure spec. on CPU spec. 100psiThermal Design ProcedureAnalytic ApproachEvaluate Solution PerformanceNumerical ApproachExperiment ApproachVerifyEvaluate heat generationAllowable thermal resistanceAllowable design spac

15、eEvaluate Chassis heat dissipationEvaluate heat exchange areaEvaluate fan flow ratePassFailInspect Structure.Production method.CostRecommend Thermal SolutionThermal Test in Working SampleVerify Overall SystemMeeting Thermal SpecificationThermal Design OK!Examine and ModifyThermal SolutionPassFailThe

16、rmal Design GuidesDesign guide for thermal (Ver. 0.2) Thank 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 point1. Thermal Modul

17、e 1)Reserve space for thermal module (Intel recommendation)Coppermine: 70*50*11.5mmTualatin: 75*55*11.5mmNorthwood: 85*60*19mm 2)It should reserve a gap between thermal module and top cover (keyboard cover) 1. Thermal Module3)The gap between thermal module exit and NB case vent should be sealed well

18、 so the hot air couldnt flow back to system. If leave an open gap along air flow path, it will affect thermal efficiency and acoustic noise. 1. Thermal Module4)The thermal module and CPU should contact well. a) The max pressure of the thermal module on CPU is 100psi. Within SPEC, efficiency of therm

19、al module increases with pressure. b) Its better to fix module on M/B by four screws (avoiding three screws) and spring design. 2. Fan 1)Fan inlet constraints: gap 35mm is needed.3mm 80% performance4mm 90% performance5mm 100% performance2)Configuration of air inlet & outlet vents can make dramatical

20、ly flow resistance; therefore high open rate is better. 2. Fan3)Dont place blocks (large ICs or connector) near or below the fan to affect airflow induced into fan.4)It is better for fixing fan by rubber instead of metal screws to avoid vibration. 2. Fan5)The fan space design has some restrictions.

21、a) For efficiency and acoustic, the gap between fins and fan blade should keep a distance of L= 5 10 mm. b) The distance W is better to keep as large as possible for good efficiency. c) Fan blade should close to fan tongue for better efficiency. 3. PCMCIA Card 1)Dont place PCMCIA on lower side of M/

22、B, near hotter ICs, and stacked up key components (HDD, CD-ROM, DVD, FDD). 2)If it needs to place PCMCIA near heat source, it is 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 w

23、ay, air can flow through this area to cool PCMCIA card.)3. PCMCIA Card3)Due to aforementioned solution, PCMCIA should place near fan in order to induce airflow to cool. 4. Key Components 1)Because HDD, CD-ROM, FDD thermal SPCE is low, these key components need to be placed in colder region. (Avoid p

24、lacing them in the middle of the system and upon M/B with hot ICs, and stacking up each other). 2)Its better to place FDD alone, not to put on/beneath CD-ROM or HDD. 5. Palm-Rest and Glid Pad 1)It should avoid placing hot components and ICs below palm-rest and glid pad. 2)It should reserve a gap to

25、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 between Inverter and LCD cover to make a thermal resistance or to add a metal plate for spreading heat. 7. Bottom case and Dimm Door 1)It should rese

26、rve a gap between IC chips and bottom case(gap 3mm is better). 2) It might have a large Al-plate on bottom case for spreading heat. 3) M/B has a hole below fan in order to induce airflow under M/B. 4)Its better to place hotter chips on upper side of M/B. 5)It should reserve a gap between Memory chip

27、s and dimm door (gape 1.5mm is better). 8. M/B Layout 1)If theres thermal issue of ICs, it should reserve space for thermal solutions(Ex. Dont place higher components beside these ICs, so it could put metal plate on ICs in future) 2)Dont place low temperature spec ICs and components near hotter regi

28、on or high temperature spec ICs and components. 9. Others 1)Its better to use the thinner or phase change TIM (thermal interface material)Ex. 28W CPU(phase change) Powerstrate 0.08mm 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 0.25m

29、m 90 Tx 0.5mm 969. Others1)Heat pipes on thermal module have some restrictions 2)The thickness shouldnt be less than 2mm when be made flat. 3)The curve radius should be larger than triple diameter at least when be bended. 4)It might need some holes on bottom case and sidewall of NB in order to induc

30、e 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; 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 f

31、anSeriesTIM: 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