1、Introduction of Thermal,GGT/RE Environment Test Team,Primary 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) convec
2、tionForced 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
3、 Ta)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: 0.00150.01
4、5 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 a,Thermal Resistance,R = V / IV: voltage = T: temperature differenceI:
5、 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 all IC chips (Chipset, VGA, RAM, PCMCIA), a
6、nd all IC chips (Chipset, VGA, RAM, Audio) in each user conditionsThermal 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
7、 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 s
8、olutionActive thermal solutionHybrid thermal solutionRHERemote Heat Exchanger,Basic Concepts for NB Thermal Design,Characteristic of a good passive componentsSpreader plate connected to CPU should be as large as possibleTemperature variation on spreader plate should be minimalCharacteristic of a goo
9、d active 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 Desig
10、n,Heat 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, st
11、ack, 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 Plat
12、e,Fan,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 point,Fan,Parallel and series operatio
13、nAcoustical 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 TIMMater
14、ialVarious material: silicon-base, carbonNon-phase changePhase change Pressure effectPressure spec. on CPU spec. 100psi,Thermal Design Procedure,Thermal Design Guides,Design guide for thermal (Ver. 0.2),Thank You!,fiber,Mesh,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,N,N,N,N,
15、S,S,S,S,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 pressure,System resistance curve,Fan curve,System operating point,Thermal Module,Reserve space for thermal module (Intel recommendation)Coppermine: 70*50*11.5mmTualatin: 75*55*11.5mmNorthwood: 85*60*19mm It should res
16、erve a gap between thermal module and top cover (keyboard cover),1. Thermal Module,The 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 air flow path, it will affect thermal efficiency and acoustic noise.,1.
17、 Thermal Module,The thermal module and CPU should contact well. The max pressure of the thermal module on CPU is 100psi. Within SPEC, efficiency of thermal module increases with pressure. Its better to fix module on M/B by four screws (avoiding three screws) and spring design.,2. Fan,Fan inlet const
18、raints: gap 35mm is needed.3mm 80% performance4mm 90% performance5mm 100% performanceConfiguration of air inlet therefore high open rate is better.,2. Fan,Dont place blocks (large ICs or connector) near or below the fan to affect airflow induced into fan.It is better for fixing fan by rubber instead
19、 of metal screws to avoid vibration.,2. Fan,The fan space design has some restrictions. For efficiency and acoustic, the gap between fins and fan blade should keep a distance of L= 5 10 mm. The distance W is better to keep as large as possible for good efficiency. Fan blade should close to fan tongu
20、e for better efficiency.,3. PCMCIA Card,Dont place PCMCIA on lower side of M/B, near hotter ICs, and stacked up key components (HDD, CD-ROM, DVD, FDD). 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 s
21、lot 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 Card,Due to aforementioned solution, PCMCIA should place near fan in order to induce airflow to cool.,4. Key Components,Because HDD, CD-ROM, FDD thermal SPCE
22、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). Its better to place FDD alone, not to put on/beneath CD-ROM or HDD.,5. Palm-Rest and Glid Pad,It should avoid placing hot component
23、s and ICs below palm-rest and glid pad. It 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 between Inverter and LCD cover to make a thermal resistance or to add a metal plat
24、e for spreading heat.,7. Bottom case and Dimm Door,It should reserve a gap between IC chips and bottom case(gap 3mm is better). It might have a large Al-plate on bottom case for spreading heat. M/B has a hole below fan in order to induce airflow under M/B. Its better to place hotter chips on upper s
25、ide of M/B. It should reserve a gap between Memory chips and dimm door (gape 1.5mm is better).,8. M/B Layout,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) Dont place low t
26、emperature spec ICs and components near hotter region or high temperature spec ICs and components.,9. Others,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
27、 Al) T-mate 0.50mm 83 (non-phase change) Tx 0.25mm 90 Tx 0.5mm 96,9. Others,Heat pipes on thermal module have some restrictions The thickness shouldnt be less than 2mm when be made flat. The curve radius should be larger than triple diameter at least when be bended. It might need some holes on botto
28、m case and sidewall of NB in order to induce airflow to dissipate heat.,35mm,Air flow,3mm 80% performance4mm 90% performance5mm 100% performance,Blocks,Bad design,L,W,Tongue,該縫隙越小Fan 效率越高, 但Noise 也會隨之上升,L: 太大, Fan效率下降; 太小, 噪音上升.,W: 作為風道, 盡量大,Single fan,Double fan,Parallel,CFM,Pressure,Pressure,CFM,Single fan,Double fan,Series,TIM: 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.,
