Messung der Wärmeleitfähigkeit von Thermal Interface Materials (TIM)

Messung der Wärmeleitfähigkeit von
Thermal Interface Materials (TIM)
Dr. Heinz Renner
LINSEIS Messgeräte GmbH
[email protected]
AKT 2016 Wien
Thermal Interface Materials (TIM)
•
•
•
•
2
Usage in Power Electronics
Thermal Pastes, Greases, Pads etc.
Thermal Conductivity AND Contact Resistance important
Standardized Measurement Method ASTM D5470-12
AKT 2016 Wien
Typical CPU Architecture
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ASTM D5470-12
Standard Test Method for
Thermal Transmission Properties of Thermally
Conductive Electrical Insulation Materials
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Instrument According ASTM D5470-12
• Two meter bars
–
(At least) two temperature sensors each
–
One heated one cooled (temperature stability
+/- 0.2 K)
–
5 µm parallelity, Ra 0.4 µm
•
Contact force necessary
•
Isolation or guard heater for the meter bars are not
necessary
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Calculations according ASTM D5470-12
Calculation of
thermal impedance
A
𝐾∗𝑚2
θ = ∗ TH − TC [
]
Φ
𝑊
λ12 ∗ A
∗ (T1 − T2 )
d
λ34 ∗ A
=
∗ (T3 − T4 )
d
Φ12 =
Φ 34
Φ =
Φ12 + Φ34
2
• Φ12 Heat flux hot meter bar[W]
• Φ 34 Heat flux cold meter bar [W]
• Φ
Heat flux specimen [W]
• λ12
W
thermal conductivity hot meter bar [m∗K]
W
• λ34 thermal conductivity cold meter bar [m∗K]
• A
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contact area of meter bar[m2 ]
Evaluations according ASTM D5470-12
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Linseis Instrument Setup
Electromechanic actuator
contact force up to 2.5 kN
Pressure up to 1 MPa to 5 MPa
Load cell for
contact force control
Cooled heat flow meter bar
(easy exchangeable)
Heated heat flow meter bar
(easy exchangeable)
LVDT for distance control/
sample thickness
90 mm meter bar distance
420 mm distance between
columns
for improved accsess to
measurement system
Linear guides
Guard heater
Two zone hotplate
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Linseis Specifications
• Meter bars:
• Easy exchangeable meter bars diameter 25 – 55 mm
• Guard heater and isolated meter bars
• Contact force up to 2.5 kN
• pressure 1-5 MPa depending on meter bar diameter
• Contact force accuracy 1%
• LVDT for distance control accuracy 0.25%
• Temperature RT to 200 °C
• Sample thickness up to 90 mm
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Measurement of a PTFE Standard
PTFE
0,025
40
35
0,02
T1
0,015
T2
0,01
T3
Cold meterbar
30
25
0
20
T4
0,005
40
Time/ min
4,0
0,40
3,5
0,35
y = 4,1795x
3,0+ 0,0012
Hot meterbar
Heat Flow/ W
Temperature/ °C
45
Thermal impedance θ /[(K*m²)/W]
50
0,30
2,5
0,25
Q12
0,20
Q34
1,5
0,15
Q
1,0
0,10
2,0
Thermal conductivity l/ (W/mK)
Thermal impedance q/ (Km²/W)
0,5
0
0
60
0,001
0,0
0,002
0,003
0,004
80
0
Thickness of specimen /m
0,05
0,005
20
0,006
40
Time/ min
0,00
60
80
Steady State Measurement
PTFE slice, dia 55mm height 3mm
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Result: λ = 0.239 W/m*K
l
θ
Measurement of a typical Stack
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Pressure Dependent Measurements
Polymer Material with Filler
2Filler Particle Sizes
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Time Dependent Measurements
Power Cycling Test
2000 cycles ~ 1 year
under normal operating
conditions
->Life Time Prediction
Thermally Conductive Grease
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More Applications
Thermal interface materials
• Solid
• Pastes
• Liquid
TEG
Peltier elements
Batteries
Electrical modules
Thermal conductivity
measurement
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Thank you for your attention!
Contact:
Dr. Heinz Renner
Linseis Messgeräte GmbH
Vielitzer Str. 43
95100 Selb/Germany
15
AKT 2016 Wien
www.linseis.com

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