2012 ANSYS, Inc. June 26, 2014 1 Release 14.5

//

Sr. Application Engineer

Ansys Inc. Korea

2012 ANSYS, Inc. June 26, 2014 2 Release 14.5

(Heat) (Heat Source)

(Heat Transfer)

(Conduction)

(Convection)

(Radiation)

(Temperature Measurement)

Appendices

Contents

2012 ANSYS, Inc. June 26, 2014 3 Release 14.5

(Heat) (Heat Source)

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1. (Heat)

(Heat)

(Heat Energy)

,

(kinetic energy)

?

?

0

: 100pK(Picokelvin)

Perfect,

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1. (Heat)

(Heat)

(Heat Transfer)

( )

( )

( )

(Conduction)

(Convection)

(Radiation)

From http://elearning.stkc.go.th/

From http://www.geo.mtu.edu/

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(Heat Source)

(Components) Joule Heating

PCB Layers Trace Joule Heating

BUS BAR Joule Heating

Wirings Joule Heating

Surroudings(Chamber)

*Heat Source/Sink

2. (Heat Source)

PCB Traces Components PCB Traces

Bus Bar

Wiring

Components

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(Heat Source) (Joule Heating)

?

, , (Ics), , , , DIPs(Dual Inline Packages), (VHSIC), PGAs(Pin Grid Arrays), LCCC(Leadless Ceramic Chip Carriers), PLCC(Plastic Leaded Chip Carriers)

2Q I R

40.0A

0.0V

[ICEPAK]

2. (Heat Source)

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(Heat Source) (Heat Generation)

CMOS Devices

Junction FET

Power MOSFET

2. (Heat Source)

From Thermal Design of Electronic Equipment, CRC, Ralph Remsburg

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(Heat Source) (Heat Generation)

Interconnects

Resistors

Capacitors

Inductors/ Transformers

2. (Heat Source)

From Thermal Design of Electronic Equipment, CRC, Ralph Remsburg

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(Heat Source) (Heat Generation)

Inductors/ Transformers (Ferromagnetic core)

2. (Heat Source)

From Thermal Design of Electronic Equipment, CRC, Ralph Remsburg

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.

.

(Components) Joule Heating

PCB Layers Trace Joule Heating

BUS BAR Joule Heating

Wirings Joule Heating

Surroudings(Chamber)

Empirical Formula Test ()

ANSYS Maxwell ANSYS SIWave ANSYS Icepak ANSYS Mechanical ANSYS CFD

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(Heat Transfer)

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1. (Heat Transfer)

(Heat Tansfer) (Conduction)

(kinetic energy) /

(Convection)

(/) (Buoyancy) (natural convection) (, ) (forced convection)

(Radiation)

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1. (Heat Transfer)

(Heat Tansfer) (Conduction)

(Convection)

(Radiation)

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1. (Heat Transfer)

(Heat Tansfer) (Conduction)

By temperature gradient (Convection)

By advection and diffusion (Radiation)

By Infrared ray

(conduction) (Convection) (radiation)

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: (Conduction)

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2. (Heat Transfer) :

(Conduction) (Conduction)

, : (Diffusion) :

Fourier 1D

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2. (Heat Transfer) :

(Conduction)

k, (W/m K)

Steel 60.5

Copper 401

Aluminum 150

FR4 0.28

S F S C A C F A F

80 20 Thermal Conductivity Copper > Aluminum > Steel >> FR4

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2. (Heat Transfer) :

S F S

C A C

F A F

S F S

C A C

F A F

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.

(Steady-State)

(k) .

.

T1 T2 T3 T4 T5

k1 k2 k3 k4

k2 >> k1 = k3 >> k4

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: (Convection)

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3. (Heat Transfer) :

(Convection)

(Convection)

(hc)

, ,

/

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3. (Heat Transfer) :

(Convective heat transfer coefficient) (hc, Convective Heat Transfer Coefficient)

5 W/m2K

Mechanism Fluid h (W/m2K)

Natural

Convection

Gases 5 30

Water 100 1000

Forced

Convection

Gas 10 300

Water 300 12,000

Oil 50 1,700

Liquid metal 6,000 110,000

Phase Change

Boiling 3,000 60,000

Condensation 5,000 110,000

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3. (Heat Transfer) :

(Convective heat transfer coefficient) (Heat Transfer Coefficient)

Nusselt Number(Nu )

: Nu = f(Ra, Pr) : Nu = f(Re, Pr)

Ra, Pr

Re, Pr Nu hc

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3. (Heat Transfer) :

(Convection) (Convection)

(Natural Convection) : , (radiation)

(Forced Convection) : /

(Flow field)

(CFD)

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3. (Heat Transfer) :

(Flow Field) : (Laminar Flow) (Turbulent Flow) (Laminar Flow)

(Random motion) (Turbulent Flow)

Osborne Reynolds Experiment

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3. (Heat Transfer) :

(Flow Field) : (Laminar Flow) (Turbulent Flow) (Re)

Re

>5E5 Transtion to turbulent along a surface on external flow

>2E4 Transtion to turbulent around a Obatacle on external flow

>2,300 Transtion to turbulent on internal flow

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3. (Heat Transfer) :

(Nondimensionless Number) (Nondimensionless Number)

Rayleigh Number, Ra

Prandtl number, Pr

Pr

1

0.7 ~ 0.8

Ra

109 (Turbulent flow)

diffusionthermallossesviscous

forcebuoyancyTxgRax

&

3

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3. (Heat Transfer) :

(Nondimensionless Number) (Nondimensionless Number)

Prandtl number, Pr

Pr

1

Pr (Air) = 0.7 Pr (Water ) = 7.9

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3. (Heat Transfer) :

(Nondimensionless Number) (Nondimensionless Number)

Grashof Number, Gr

Peclet Number, Pe

Pe

1

Gr

< 108 (Laminar flow)

108 ~109 (Transition)

>109 (Turbulent flow)

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3. (Heat Transfer) :

(Nondimensionless Number) (Nondimensionless Number)

Richardson number, Ri

Forced

Natural

U

TLgRi

2

0

Ri

~ 1 (mixed/combined convection)

10 (natural convection)

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3. (Heat Transfer) :

Air Properties @20

Properties Values Unit

Density, 1.2047 kg/m^3

Dynamic Viscosity, 1.8205e-5 kg/m.s

Kinematic Viscosity, 1.5111e-5 m^2/s

Specific Heat, Cp 1.0061e+3 J/kg.K

Conductivity, k 0.025596 W/m.K

Prandtl number, Pr 0.71559

Thermal Diffusivity, 2.1117e-5 m^2/s

Thermal Expansion Coefficient, 3.4112e-3 1/K

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3. (Heat Transfer) :

- Small Electronics( )

= 10 x 10 x 5 (mm3) = O.5 Watt

Max V = 0.25m/s Max T = 92.0

()

()

Ra 7.6E3 5.2E3

Pr 0.71 0.71

Re 1.65E2 2.0E2

Ri 0.39 0.186

Gr 1.1E4 7.31E3

/

(0.3m/s, ) Max V = 0.34m/s Max T = 69.9

(0.3m/s,) Max V = 0.34m/s Max T = 59.6

()

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3. (Heat Transfer) :

- Small Electronics( )

= 10 x 10 x 5 (mm3) = O.5 Watt

(0.3m/s, )

Max V = 0.34m/s Max T = 63.1

()

()

Ra 7.6E3 4.1E3

Pr 0.71 0.71

Re 2.0E2 2.0E2

Ri 0.39 0.146

Gr 1.1E4 5.8E3

/

(0.3m/s, ) Max V = 0.34m/s Max T = 59.3

()

()

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- Cases?

3. (Heat Transfer) :

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3. (Heat Transfer) :

- Small Electronics(SSR ..)

= 40 x 30 x 15 (mm3) = 30.0Watt

Max V =