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Introduction of Thermal

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Title: Introduction of Thermal


1
Introduction of Thermal
  • GGT/RE Environment Test Team

2
Primary Mechanic of Heat Transfer
  • Thermal energy transport
  • cause by temperature difference, high T -gt low T
  • Conduction
  • Heat transferring by solid medium
  • Convection
  • Transferring energy between solid surface and
    fluid
  • Mass transport
  • Natural (free) convection
  • Forced convection
  • Radiation
  • Heat transferring by electromagnetic waves

3
Conduction
  • Fouriers Law
  • Q -KA ?T/?L
  • Q heat transfer rate
  • A cross-sectional area of heat flux
  • ?T/?L temperature gradient
  • K thermal conductivity (W/mk)
  • Ex. Al 230
  • Cu 380
  • Mylar 1.8

4
Convection
  • Newtonian cooling Law
  • Qc hc As (Ts Ta)
  • Qc convection heat transfer rate
  • As surface area
  • Ts surface temperature of solid
  • Ta tmperature of ambient
  • hc heat transfer coefficient, f(flow type,
    body geometry, physical property, temperature,
    velocity, viscosity)
  • Natural convection Forced convction
  • hc of air, natural convection 0.00150.015
    W/in2?
  • forced convection 0.0150.15
    W/in2?

5
Radiation
  • Qa esAF1-2( Ts4 Ta4)
  • Qa radiation heat transfer rate
  • e emissivity, 0 ? e ? 1
  • s Stefan-Boltzmann constant
  • A surface area
  • F1-2 view factor
  • Ts temperature of body s
  • Ta temperature of body a

6
Thermal Resistance
  • R V / I
  • V voltage ?T temperature difference
  • I current Q heat
  • Conduction
  • Rk ?L/KAk
  • Convection
  • Rs 1 / hcAs
  • Radiation
  • Ra (Ts Ta) /esAF1-2( Ts4 Ta4)

7
Basic Concepts for NB Thermal Design
  • Thermal Design Target
  • Thermal design must meet thermal spec. of CPU,
    all key components (HDD, FDD, CD-ROM, PCMCIA),
    and all IC chips (Chipset, VGA, RAM, PCMCIA),
    and all IC chips (Chipset, VGA, RAM, Audio) in
    each user conditions
  •  Thermal Resistance
  • Tj-a (Tj Ta) / Pcpu
  • T j-a CPU junction to ambient thermal
    resistance
  • Tj CPU junction temperature
  • Ta ambient temperature
  • Pcpu CPU power

8
Basic Concepts for NB Thermal Design
  • System Thermal Coupling effect
  • Tj-a (Tj Ta Tsys) / Pcpu
  • Tsys system temperature Psys T
  • SPi?i, (i DRAM, Chipset, HDD, FDD,
    CD-ROM)
  • R thermal coupling factor between Pcpu and Psys
  • Tj CPU spec. for Intel 100?
  • Ta OEM spec., 35?
  • Tj-a, Tsys OEM design dependent, Tsys 1015?

9
Basic Concepts for NB Thermal Design
  • Thermal Solutions
  • Passive thermal solution
  • Active thermal solution
  • Hybrid thermal solution
  • RHE
  • Remote Heat Exchanger

10
Basic Concepts for NB Thermal Design
  • Characteristic of a good passive components
  • Spreader plate connected to CPU should be as
    large as possible
  • Temperature variation on spreader plate should
    be minimal
  • Characteristic of a good active component
  • Air inlet and outlet should be clearly defined
  • Length of air passage through NB should be small
    to keep pressure drop low, flow rate high
  • Possible reduce noise level of the fan
  • Design must be capable of venting a portion of
    hot air from NB inside

11
Important Components For Thermal Design
  • Heat Sink
  • Heat Pipe
  • Fan
  • TIM ( Thermal Interface Material)
  • Combination of aforementioned components

12
Heat Sink
  • Material
  • Material A1050 A6063 ADC12
    C1100
  • K(W/mk) 230 210 192
    384
  • Specific gravity 2.71 2.69 2.70
    8.92
  • Production
  • Die-casting
  • Extruded
  • Q -KA?T/?L
  • Fin, Q hA?T
  • Die-casting, extrusion, folder, stack, soldering
    fins

13
Heat Pipe
  • Basic configuration and characteristic
  • Basic specification
  • Material copper
  • Working fluid pure water
  • Standard working temperature 0100?
  • Size ?3, ?4, ?5, ?6, ?8
  • Typical heat pipe wick structures
  • Fiber, mesh, groove, powder
  • Typical modification of heat pipe
  • Flattening
  • Bending
  • Heat Plate

14
Fan
  • Structure
  • Rotator magnetic blade, shaft
  • Stator bearing, wire, stainless plate
  • Control circuit
  • Theory
  • Type
  • Axial fan
  • Blower fan
  • Selection
  • Total cooling requirement
  • Q Cp m ?T ? Cp CFM ?T
  • Total system resistance / system characteristic
    curve
  • System operating point

15
Fan
  • Parallel and series operation
  • Acoustical noise level (dB)
  • To achieve low noise should consider
  • System impedance
  • Flow disturbance
  • Fan speed and size
  • Temperature rise
  • Vibration
  • Voltage variation
  • Design considerations

16
TIM
  • Thermal Interface Material
  • To reduce contact thermal resistance between CPU
    die and thermal module
  • Important of TIM
  • Material
  • Various material silicon-base, carbon
  • Non-phase change
  • Phase change
  • Pressure effect
  • Pressure spec. on CPU spec. 100psi

17
Thermal Design Procedure
18
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19
Thermal Design Guides
  • Design guide for thermal (Ver. 0.2)

20
  • Thank You!

21
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22
??(??)
????
fiber
Mesh
??
23
??????
groove
Powder ?? ???????Heat Pipe??, ??????
24
N
????????
N
?Hall IC ?????N.S.?, ????????????????????????
S
S
S
S
N
N
25
Static pressure
Fan curve
System resistance curve
System operating point
CFM(ft3/min)
26
Thermal Module
  • Reserve space for thermal module (Intel
    recommendation)
  • Coppermine 705011.5mm
  • Tualatin 755511.5mm
  • Northwood 856019mm
  • It should reserve a gap between thermal module
    and top cover (keyboard cover)

27
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.

28
1. 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.

29
2. Fan
  • Fan inlet constraints gap 35mm is needed.
  • 3mm 80 performance
  • 4mm 90 performance
  • 5mm 100 performance
  • Configuration of air inlet outlet vents can
    make dramatically flow resistance therefore high
    open rate is better.

30
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 of
    metal screws to avoid vibration.

31
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 tongue for better
    efficiency.

32
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 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.)

33
3. PCMCIA Card
  • Due to aforementioned solution, PCMCIA should
    place near fan in order to induce airflow to
    cool.

34
4. Key Components
  • Because 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).
  • Its better to place FDD alone, not to put
    on/beneath CD-ROM or HDD.

35
5. Palm-Rest and Glid Pad
  • It should avoid placing hot components 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.

36
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.

37
7. Bottom case and Dimm Door
  • It should reserve a gap between IC chips and
    bottom case(gap gt 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 side
    of M/B.
  • It should reserve a gap between Memory chips and
    dimm door (gape gt 1.5mm is better).

38
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 temperature spec ICs and
    components near hotter region or high temperature
    spec ICs and components.

39
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 Al)
  • T-mate
    0.50mm 83?
  • (non-phase change) Tx
    0.25mm 90?
  • Tx
    0.5mm 96?

40
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 bottom case and
    sidewall of NB in order to induce airflow to
    dissipate heat.

41
3mm 80 performance 4mm 90 performance 5mm
100 performance
Air flow
35mm
42
Bad design
Blocks
43
Tongue
L ??, Fan???? ??, ????.
L
W
?????Fan ????, ?Noise ??????
W ????, ???
44
Pressure
Single fan
Parallel
Double fan
CFM
Pressure
Single fan
Series
Double fan
CFM
45
TIM thermal interface material ?????????????????,
????????????????????. ????????, ?????, ???,
?????????????. ?????????????????????????,
???????????????.
46
(No Transcript)
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