transient plane source techniques for measuring thermal conductivity of various materials evitherm...

Transient Plane Source Techniques for measuring Thermal Conductivity of Various MaterialsEvitherm

September 15, 2003

Dr. Lars HlldahlHot Disk AB

Hot Disk

or

Transient Plane Source, TPS

or

Gustafsson Probe

or

G-Probe

The technique is based around:-A unique sensorA new mathematical model for thermal conductivityA Transient Plane Source in infinite material- Special electronics to collect dataDesigned for accuracy and precision

The SensorA double spiral made of Nickel metal foil, cladded by Kapton or Mica to provide electrical insulation from the sample. The diameter varies from 1 mm up to 60 mm. It connects to the electronics, which sends out a current during a selected time, while the voltage drop is recordedSee in the following four slides the historical development of Hot Diskfrom Hot Wire Hot Strip !

Hot Wire

About 1960-tiesMetal wire in contact with the sampleOK for liquids, but not for solids contact resistance problems

Hot Strip

Development of Hot Wire the wire.flattened outbetter contact on sample

From a Strip..to a spiralcovers larger area on smaller sample

So.the story is

from

Hot Wire

to

Hot strip

and next stepTransient Plane SourceThis is Hot Disk

Sensor embedded in the sample. Heat can spread in all directions

A transient recordingPowerTimeTimeVoltage=resistance=temperatureSend in power...and measure at the same timeFor good conductors:high power, short timeFor good insulators: low power, long time

Ideally, the sensor is surrounded by infinite sample in all direction. Cant see the edge, the temperature increase doesnt reach the edges.Both Conductivity and Diffusivity are measured, and from them Heat Capacity is calculatedHeat dissipation in infinite sample

Sample

Parameters of importance: POWER, TIME SENSOR SIZE The relation between Diffusivity, Time for measurement and radius of sensor is called Total to Characteristic Timex tr x r

SampleSensor=1This value between 0.3 1.0 satisfies the basic assumption done for the Heat Conductivity equation: A Plane Source in Infinite Material

Variants of the TPS methodBy varying sensor size, power and time in the basic method, thermal conductivity over morethan 4 orders of magnitude can be covered.To cover more applications, some variants have been developed

Thin Film MethodSamples like paper, textile, cloth, polymer films, etc.Background material

Sample Sensor Sample

Background materialThickness from ~ 10m ~ 500m Conductivity from ~ 0.01W/mK ~ 10W/mKBackground material is good conductor, experiment parameters as if this is the sample: high power, short time

Thin Film often uses a square, naked Ni-sensorwhich is most sensitive, but also cladded sensors can be used

Slab MethodInsulator

SampleSensorSample

InsulatorFor good conductors, >10 W/mK- Ceramic, metals, Si-wafer, SiC. Etc.Relation between Sample Thickness/Sensor radius 0.03 < t/R < 0.75 - Different radii to match different samples

Developing Slab Method-Air is very insulating

Anisotropic samplesRadial directionConductvityDiffusivity

Axial directionConductivityDiffusivityTo solve the heat conductivity equation in this case: Heat Capacity Cp must be known!

Anisotropic sampelsTensile testing bars, polymer matrix with fiber reinforcement in the plan. Thickness2 mm.

radial W/mK axial W/mK radial mm2/s axial mm2/s mm2/s W/mK

Diagr1

0.1060505330.08107838910.23005423070.1758824394

0.09393397590.06523192770.3021892040.2098536139

0.10433047190.07235122880.35020875380.2428632134

laxial [W/mK]

kaxial [mm2/s]

lradial [W/mK]

kradial [mm2/s]

% Fiber

l [W/mK] k [mm2/s]

Results

Results :Dragprov5%Number of Rows:9

File:(Points)TemperatureAx.Th.ConductivityAx.Th.DiffusivityRad.Th.ConductivityRad.Th.DiffusivityAx.Pr.DepthRad.Pr.DepthTemp.Incr.Temp.DriftTotal/Char.TimeTime Corr.Mean Dev.Disk Res.

Dragprov_1procent. 1.ani( 13- 200,tc)Rumstemp 23 deg. C0.10671190880.08158402820.2277899990.17415137541.8029458632.63416859942.00744473260 (No corr.)0.32396674790.06818926980.00100373132.4391883427



Average0.10610.08110.2300.176

Stdev0.00070.00050.0020.002

Stdev %0.60.60.90.9

Dragprov_2p5procent. 3. 1.ani( 17- 200,tc)Rumstemp 23 deg. C0.09324416070.06475288940.30342819120.21071402171.60623723812.89752260081.80809214650 (No corr.)0.39198275750.05979339940.00101941492.438608362



Average0.09390.06520.3020.2099

Stdev0.00060.00040.0010.0009

Stdev %0.70.70.40.4




Average0.10430.07240.35020.2429

Stdev0.00020.00010.00040.0003

Stdev %0.20.20.10.1

Outp.power.Meas.timeSp.heat SampleRadius

Dragprov_1procent. 1.ani0.02101.3082.001



Dragprov_2p5procent. 3. 1.ani0.02101.442.001






laxial [W/mK]kaxial [mm2/s]lradial [W/mK]kradial [mm2/s]Cp [MJ/m3K]

1Sample 1%Average0.10610.08110.2300.1761.308

2.5Sample 2.5%Average0.09390.06520.3020.20991.44

5Sample 5%Average0.10430.07240.35020.24291.442

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Results

0000

0000

0000

laxial [W/mK]

kaxial [mm2/s]

lradial [W/mK]

kradial [mm2/s]

% Fiber

l [W/mK] k[mm2/s]

Parameters

Parameters :Dragprov5%Number of Rows:9

File:TemperatureOutp.power.Meas.timeSp.heat SampleRadiusTCRDisk TypeTemp.drift rec.

Dragprov_1procent. 1.aniRumstemp 23 deg. C0.02101.3082.0010.004693KaptonYes



Dragprov_2p5procent. 3. 1.aniRumstemp 23 deg. C0.02101.442.0010.004693KaptonYes






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T-t

Temperature-time graph :Number of Columns:0

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T(drift)

Temperature drift graph :Number of Columns:0

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T-f(Tau)

Temperature-f(Tau) graph :Number of Columns:0

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Diff

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Single sided methodIf you do not want to cut your precious sampleput the sensor on the surface..and back it up with a known sample. Tell the software the properties of the known, and run the analysis as before.In principal, the more similar, the better

In Transient Methods, like Hot Disk, the contact resistance does not cause any problem.

This is not the case with Steady State Methods, wherethis is a limitation for the use.

The following slides explains how Contact resistanceis dealt with, and gives an illustrative example.

Ideally, the sensor is surrounded by infinite sample in all direction. Contact areaTemp CTime sCut off here!

Ideally, the sensor is surrounded by infinite sample in all direction.

If this should occur, the later part of the raw data are removedCut off here!Temp CTime s

Measuring coated and uncoated ceramicsVaristors made of ZnO ceramicsuncoated surfacesurface coated by Al-metal, 60m thickMeasuring with same conditions sensor, time, power,temperature

It seems like the Al-metal coating was insulating?A metal like Al ?In this case the sprayed metal was very porous. The conductivity was about 0.5 W/mK60m of porous metal added to the kapton coating increases the temperture about 4 times!

Some resultsGreen Metal Coated W/mK std % W/mk std% 23 C 24.70 (0.2) 24.69 (0.8) 300 C 12.67 (2.2) 13.36 (0.8) Sensor radius 6.675 mmSensor radius 14.65 mm23 C 24.71 (0.8) 24.88 (1.0) 300 C 12.19 (1.3) 13.08 (0.4) Mica sensorKapton sensorMica sensorMica sensor

Constant T after initial period

Thin film making use of contact resistance

Temp. vs time without sample

Temp. vs time with sample

Temp

Time

Measuring liquids-vertical sensor-low power-short timeto avoid convectionPut it in a heating/cooling bath, and run at different temperatures- liquids with a viscosity as low as water and methanol can be measured

Sheet1

-350.3007

-200.33110.2515

00.37230.5379

00.5271

250.6191

250.6366

400.44310.711

800.51880.90440.3127

1000.3605

Sheet1

Mix Gly/Water

Water

Pure Glycol

Temp C

W/mK

Conductivity

Sheet2

-350.11442.6208

-200.10982.2910.12322.6894

00.13092.8490.15123.5572

00.14553.64

250.16743.7058

250.17953.5487

400.13763.2220.20653.445

800.08933.5040.14993.46940.27983.2392

1000.11243.207

Sheet2

000

000

000

000

000

000

000

000

000

Glycol

Mixture

Water

Temp C

mm2/s

Diffusivity

Sheet3

Sheet3

-352.6208-35

2.2912.6894-20

02.8493.5572

003.64

25253.7058

25253.5487

403.2223.445

3.5043.46943.2392

3.207100100

Cp Glycol

Cp Mixture

Cp Water

Temp C

MJ/m3K

Heat Capacity

Pure water:

Temperature Time Conductivity std Diffusivity std Heat Capacity std C s W/mK % mm2/s % MJ/m3K % 0 5 0.538 0.4 0.151 1.7 3.56 1.3 0 2.5 0.530 0.8 0.146 1.9 3.64 1 25 see A 2.5 0.619 2.4 0.167 6.5 3.71 3.9 25 see B 2.5 0.637 1.5 0.180 3. 7 3.55 2.3 40 2.5 0.711 0.7 0.207 1.6 3.45 0.9 80 1 0.904 2.9 0.280 6.8 3.24 4.1

Measuring at high temperaturesSampleMuffle furnace from RTto 700 CMica cladded sensor

How accurate is Hot Disk ?An article by professor Torbjorn Log*compares results from 5 different materials, measured with different techniques, with Hot Disk measurements.*T.Log, S.E.Gustafsson, Transient Plane Source (TPS) Technique for Measuring Thermal Transport Properties of Building Materials, Fire and Materials 19, 43-49 (1995)

Layer Thickness : The thickness of the copper layers and intermediate insulating glass epoxy layers is specified in Table 1 using millimeters (mm).

Table 1 Cross sectional details of the Test PCB #4's construction.

PCB #

Thickness of each Copper

Layer (micrometers)

Representation of Construction

(Red=Copper and Black = FR-4)

Thickness of each FR-4

Layer (millimeters)

PCB #4

4-Layer

Outer Signal Layer - 70 (m

Top Plane Layer - 35 (m

Bottom Plane Lyr - 35 (m

Outer Signal Layer - 70 (m

0,30 mm (2 Prepreg Layers)

0,22 mm (core)


0,40 mm (core)


Notes: the Core and Prepreg layers are both considerd to have the same thermal conductivity values as FR-4.

ITHERM 2000: Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems,

May 23-26, 2000, Las Vegas, NE, USA.

Using Experimental Analysis to Evaluate the Influence of Printed Circuit Board

Construction on the Thermal Performance of Four Package Types

in both Natural and Forced Convection

John Lohan1, Pekka Tiilikka2, Peter Rodgers3, Carl-Magnus Fager2, Jukka Rantala2

1 Mechanical & Industrial Engineering Department, Galway-Mayo Institute of Technology, Galway, Ireland

2 Nokia Research Center, P.O. Box 407, FIN-00045 NOKIA GROUP, Finland

3 Mechanical & Aeronautical Engineering Department, University of Limerick, Limerick, Ireland

[email protected]

ITHERM 2000: Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems,

May 23-26, 2000, Las Vegas, NE, USA.

Using Experimental Analysis to Evaluate the Influence of Printed Circuit Board Construction on the Thermal Performance of Four Package Typesin both Natural and Forced Convection

John Lohan1, Pekka Tiilikka2, Peter Rodgers3, Carl-Magnus Fager2, Jukka Rantala2

1 Mechanical & Industrial Engineering Department, Galway-Mayo Institute of Technology, Galway, Ireland

2 Nokia Research Center, P.O. Box 407, FIN-00045 NOKIA GROUP, Finland

3 Mechanical & Aeronautical Engineering Department, University of Limerick, Limerick, Ireland

[email protected]

These are the samples..with properties found with different techniques.Almost 4 orders of magnitude

Results for diffusivity. Small deviations but who is right?

Results on Conductivity almost perfect agreement

Measuring on a NIST StandardExtruded Polystyrene, cert. No 1453Values given for a range of density and temperatures for a thickness of 13.4mmDensity from 38 kg/m3 to 46 kg/m3at 295 K, the given Thermal Resistance (m2K/W),converted to Thermal Conductivity by using the thicknessgives a range 0.0328-0.0338 W/mK

13.4 mm100 mmDensity 43.8 kg/m3

40.4 kg/m34 possible combinations to place the sensorSide combinations Results (W/mK) Std % 1-2 0.03394 0.12 2-1 0.03379 0.042-2 0.03451 0.081-1 0.03346 0.23

So.what Hot Disk can do in Evitherm..

measure most materials from 0.005 to 500 W/mK..

develop new applications

provide consultancy, measurements and equipment,

as well as training, courses, seminarsIn Uppsala development electronics, manufacturing, applications, testingservice

In Gteborg development sensors/software applications, testing

Thats all folks !

Thank you for your attention.

Metal insertVacuum feed throughSample holder and sensor

Outer lid with vacuum connection, gas valves, pressure valveand cables

transient plane source techniques for measuring thermal conductivity of various materials evitherm...

Documents

heat conductivity equation

high power

time sensor size

hot wireabout

hot disksensor

low power

radius of sensor

sample thicknesssensor