Thermal Interface Material Thermal Interface Material Performance Measurement Performance Measurement Long Win Science & Technology Co., Ltd. www.longwin.com longwin@longwin.com 886-3-4643221 886-3-4986875 2007/07/16
Contents Contents 1. Introduction Heat Transfer 2. Thermal Conductivity Measurement 3. Contact Resistance 4. Thermal Resistance (Impedance) Measurement
Contents Contents 1. Introduction Heat Transfer 1. Introduction Heat Transfer 2. Thermal Conductivity Measurement 3. Contact Resistance 4. Thermal Resistance (Impedance) Measurement
a T － P J T = Ja R LED Thermal Flow Path
) 4 Ta ) ) Ta Ta − − T X − 4 Heat Transfer Mechanism ∂ ∂ Ts Ts Ts kA ( ( ( A A = εσ hA − h = = = Q conduction Q convection Q radiation & & & A. Conduction A. Conduction B. Convection C. Radiation
h (Heat Transfer Coefficient) 2 * Type h [w/m 2 *℃ ℃] ] Order Type h [w/m Order Nature convection 2~25 0 Force convection 25~250 1 Liquid force convection 50~20,000 3 Evaporate and condense 2500~100,000 4 Radiation 0
Thermal Resistance and Ohm’s Law Electrical Resistance Thermal Resistance Temperature A Voltage A Power Current Dissipation Temperature B Voltage B Voltage A - Voltage B Temp A - Temp B θ AB = R = Power Dissipation Current Units: ° C/Watt Units: Ohm
Thermal resistance analysis θ j/bk ≤ 0.65 -------------- TIM, Contact Tamb θ bk/hp1 ≤ 0.05 -------------- Bounding, Pipe θ hp1/hp2 ≤ 0.02 -------------- Pipe Tfin θ hp2/fin ≤ 0.05 -------------- Bounding, Fin θ fin/amb ≤ 0.23 ~ 0.53 ---- Fan Thp2 Heat Pipe Thp1 Sink Tblock TIM Tjunction
Application Components: A. Cooler B. Pad / Grease C. Power supply D. Interface card E. LED thermal module … System: A. D/T PC B. N/B PC C. Servo system D. Rack system E. Projector …
Application
Application
Thermal Conduction Thermal Conduction a. Solid state structure, a. Solid state structure such as metal heat sink. b. Fluid state structure, b. Fluid state structure such as: (a) heat pipe structure (b) compressor coolant structure c. Liquid state structure, c. Liquid state structure such as water cooling structure.
Fourier Law Fourier Law h − T T = c Q K A L DT ＆ Thickness Not Easy for DT Thickness Measurement Q ： transferred heat K ： thermal conduction coefficient of solid state zone of substance A ： effective heat transfer area of solid state zone Th ： temperature in high-temperature solid state zone Tc ： temperature in low-temperature solid state zone L ： sampling distance between high and low temperature solid state zones
Follow ASTM 5470D Standard Follow ASTM 5470D Standard FORCE P Insulator Guard Heater H T g H Insulator Heater T m H T1 Upper Meter Bar T A T2 LVDT measure Specimen Thickness T3 T D Lower Meter Bar T4 T5 Reference Calorimeter T6 ASTM (American Society for Testing and Materials) Cooling Unit Insulator
Longwin TIM Tester Scheme Cylinder with programmable loading Ball joint (Gimble) to make sure contact surface pressure load uniform Q out T i1 or Ta Water cooling or air cooling module T L3 Thermal isolated T L2 material T L1 Specimen LVDT measure Td pad/grease Thickness Tc or grease Tu Tm Q in Thermal isolated T l h material Heat Source Q in = I × V @ Upper and lower block with alignment fixture
Longwin TIM Tester- 9091IR
Longwin TIM Tester- 9091IR Bond Line Thickness Effect Pressure Effect
Longwin TIM Tester- 9091IR Thermal Cycle Test for Reliability
Contents Contents 1. Introduction Heat Transfer 2. Thermal Conductivity Measurement 2. Thermal Conductivity Measurement 3. Contact Resistance 4. Thermal Resistance (Impedance) Measurement
Measurement ） Measurement K ( K Thermal Conductivity ） ( Thermal Conductivity 1. Laser flash (Transient) 1. Laser flash 2. Hot disk (Transient) 2. Hot disk 3. Hot wire (Transient) 3. Hot wire 4. Heat flux (Steady) 4. Heat flux
Measurement K Measurement K Transient Steady state ∂ ⎡ ⎤ T 2 k m & = − α = Q k A ⎢ ⎥ ∂ ρ ⎣ ⎦ X C s p α = Thermal diffusivity ρ = Density = Heat capacity C p 2 m m = × = × m Velocity Length s s α = × × C V L 1
Laser Flash Laser Flash
Hot Disk （ Transient Plane Source Method, TPS ） Thermal Insulation Hot Disk Hot Disk
Heat Flux Heat Flux ASTM 5470D ASTM 5470D FORCE P Insulator Guard Heater H T g H Insulator Heater T m H T1 Upper Meter Bar T A T2 LVDT measure Specimen Thickness T3 T D Lower Meter Bar T4 T5 Reference Calorimeter T6 Cooling Unit Insulator
LW 9021D ASTM-5470 D Follow
Longwin TIM Tester- 9091IR
Heat Flux Heat Flux ASTM E1530 COLD FACE HEATER COLD FACE HEATER Copper surface plate Tu Guard heater Tg Test sample d Heat flow (Q) Heat flow transducer Tl Copper surface plate Th HOT FACE HEATER HOT FACE HEATER At thermal equilibrium : Rs = N (Tl-Tu) / Q – R0 Where Rs = sample thermal resistance N = proportionality constant Tl = lower surface temperature Tu = upper surface temperature Q = heat flux transducer output R0 = constant thermal resistance
Bar Material K Measurement cooling = = T T T T 3 T T 1 2 5 6 2 3 T 6 = = T T T T T 2 3 34 4 5 T 5 T 4 T 3 Fourier Law thermal Isolate T 2 Material ∂ T = − q KA T 1 ∂ X Heat Flux Heat Source
Bar Material K Measurement Fourier Law with ASTM-5470 D Thermal Guard concept, For steady state can be got k value.
Table of Thermal Conductivity Diamond 895-2300 Silver 429 Copper 386 Gold 317 Aluminium 237 Brass 120 Platinum 71.6 Iron 80.2 Lead 35.3 Quartz (273K) 6.8-12 Glass 1.35 Wood 0.04 Styrofoam 0.033 Wool 0.04 Silica aerogel 0.017 Air (100 kPa) 0.0262 Water 0.6062 W Ice (273K) 2.2 0 (@ 298K) M C Mercury 8.514
Contents Contents 1. Introduction Heat Transfer 2. Thermal Conductivity Measurement 3. Contact Resistance 3. Contact Resistance 4. Thermal Resistance (Impedance) Measurement
Contact Resistance Contact Resistance Thermal Contact Resistance = Func.( roughness, pressure, temperature, material, TIM ) Thermal Contact Resistance = Rc_upper + Rc_lower
Surface Roughness Measurement
Surface Roughness Measurement
Surface Roughness Measurement
Table of Contact Resistance Different Metal Surface Roughnes Temperature Pressur Impedance s μ m ℃ e MPa Contact Resistance ℃*cm 2 /w 20-30 10 20 SS-Al Polish 3.45 20-30 20 20 SS-Al Polish 2.78 1-2 20 10 SS-Al Polish 0.61 1-2 20 20 SS-Al Polish 0.48 1.3-1.4 20 5 Al-Cu Polish 0.24 1.3-1.4 20 15 Al-Cu Polish 0.18 4.4-4.5 20 10 Al-Cu Polish 0.83 4.4-4.5 20 20~35 Al-Cu Polish 0.45 (From Holman, Ref.12, and Kreith and Bohn, Ref.16)
Table of Contact Resistance Same Metal Surface Roughness Temperature Pressure Impedance ℃ μ m MPa Contact Resistance ℃*cm 2 /w 1.14 20 4~7 304 Stainless Steel Polish 5.26 2.54 90~200 0.3~2.5 416 Stainless Steel Polish 2.63 2.54 150 1.2~2.5 Aluminium Polish 0.88 3.81 20 1~5 Copper Polish 0.18 1.27 20 1.2~20 Copper Polish 0.07 0.25 30 0.7~7 Copper (vacuum) Polish 0.88 (From Holman, Ref.12, and Kreith and Bohn, Ref.16)
Contact Resistance v.s. Pressure
Contact Resistance Measurement
Contents Contents 1. Introduction Heat Transfer 2. Thermal Conductivity Measurement 3. Contact Resistance 4. Thermal Resistance (Impedance) 4. Thermal Resistance (Impedance) Measurement Measurement
A c T × h − L Definition of Thermal Resistance 2 T 2 T T Q 1 − Q − A T 1 K T = = = Q R I Area = A L A × 2 2 T T Q 1 − Q − T = 1 T R T 1 T 2 = I
CPU Cooler Thermal Resistance Ta Fan Air flow rate Cooler Module & flow pattern Q out Tc Tu h − Tm T T = Meter Bar thermal isolated c Q K A Q in material L T l － Ta Q ine = I × V T Heat Source R = c Q out Heat loss
Heat Flux Power 1.Meter Bar Size ： a. 31 × 31 mm b. 37 × 37 mm c. 25.4 × 25.4 mm d. User define 2. Power Supply ： a. 180W b. 300W
Test Application DT Cooler Module Test NB Cooler Module Test
TIM Thermal Resistance P PAD / Grease Q outh T i1 water cooling or air cooling T L3 thermal isolated T L2 − l T Tu material = − T T c u T L1 X Td 1 specimen /pad − T T or grease = + Tc L1 L2 T T Tu d L1 X 2 − l Tm T Tu Q inh = ⋅ Q KA thermal isolated material X T 3 − T T = c d R Q ine = I × V Heat Source Q heat loss
TIM Test Section-9091IR
a T － P J T = Ja R LED Thermal Resistance
LED Junction Temperature Measurement
LED Graphite Heat Spreader Copper Base Mount LED Temperature Sensor Graphite Sheet
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