thermally conductive plastics in led lamps - dsm · pdf filethermally conductive plastics in...

Stanyl® TC

Copyright © DSM Engineering Plastics 2010

Thermally conductiveplastics in LED lamps

Rob Janssen, Lucien Douven, Abel Pot, Hans van Dijk

Thermally conductive plastics

Copyright © DSM Engineering Plastics 2010

DSM Engineering Plastics - Stanyl® TC Unlimited. DSM

LED is the lighting solutions of the future. Current lightingapplications are designed with this new LED technology.Stanyl TC is the best long term solution offeringproductivity gains, resulting in energy savings, coast andmaterial reduction.

Scope

Trends in the market of lighting solutions

Stanyl TC, the plastic solution for LED applications

How does it work

Application examples

Proven thermal management: the measurements

Conclusion

Contact

Appendix

DSM Engineering Plastics - Stanyl® TC

Trends in lighting applications

To leverage existing lighting infrastructure, LED retrofit lamps have beendeveloped. They allow LED bulbs to be substituted for incandescent, halogenor fluorescent bulbs in existing lighting infrastructure.The significant benefits of LED Lighting – energy savings, longer life, higherefficiency and reduced environmental impact – as well as new legislation areencouraging consumers to replace conventional lighting lamps with high-power LED lamps.


Stanyl TC in LED applications

Trends:

Application:

Features:

Eco+:

Energy saving and extendedlifetime in lighting solutions

High energy efficientLED lamps

Thermal conductivity,design freedom, highproductivity

Aluminum replacement,Productivity gains,energy savings andmaterial reduction

Philips Master LED lamp


Thermally conductive plasticsWhen are they of use?Plastics are thermal insulatorswith typical conductivities

W/mK

This low value is due to:• Random orientation of polymer• chain segments• Weak coupling between polymer• chains• Vibrations only transmit efficiently• along a chain contour


2.0polymer

Thermally conductive plasticsWhen are they of use?Measuring the thermal conductivityIf we measure the thermalconductivity of Dyneema® ropes, i.e.,Moleculary aligned UltraHighMolecular Weight Polyethylene,

W/mK [1D] is obtained.


45polymer

Thermally conductive plasticsWhen are they of use?In metals and crystalline ceramics,vibrations can transmit efficientlyin 2D or 3D

Therefore, Metals, ceramics have TCvalues W/mK.

We rely on fillers to make TC-plastics.


1001100

ceramic

metal

Thermally conductive plasticsWhen are they of use?The compound thermal conductivity is described fairly accurately by the Halpin-Tsai equation with Lewis-Nielsen correction [Ind.eng.chem., Fundam., 13(1) (1974),17-20]


22max,2

max,2

12

12

2

21

11

/1/

2

11

AB

DLA

BAB

Input: plastic, filler, amount of filler, shape of the filler particles

Thermally conductive plasticsWhen are they of use?Filler particle aspect ratio L/D~15:


Thermally conductive plasticsWhen are they of use?Improved filler with muchhigher aspect ratio:

Conclusion:best we can do in thermallyconductive plastics is

20W/mK, which is wellbelow 100W/mK formetals and ceramics.


Thermally conductive plasticsWhen are they of use?Does this mean thatmetal replacement isnot an option?


Heat source Convective coolingor metal contact

x=0 x=d

)(

0

airdxdx

xin

TThxT

tTqx=0:

x=d:

c pTt

2 Tx 2

inq

Thermally conductive plasticsWhen are they of use?No it doesn’t:


Convectionlimited

Conductionlimiteddq

T in

In a convection limitedsituation, one can lower(=replace metal) withoutincreasing parttemperatures. Just look forthe right applications.

Target application: LED lamp holder

Plastics for the lamp-holder


Not: package material.Package material needs to have highreflectivity + retention of reflectivity.

Lamp holderneeds thermalconductivity.


Why? Because LED is future in lighting



LED enemy #1 is heat. Heat reduces LED lifetime and light output,it needs thermal management


50

60

70

80

90

100

2 y 6 y

T junction = 63 C

T junction = 74 C

Useful life of high brightness white LED at different operating temparatures

Ligh

t out

put [

%]

Time [hours]

1000 10000 100000


Thermal management can be done in aluminum with =150 W/m*K


TLED = 125.7°C - Tmin = 115.1°C


It can not be done with regular thermoplastics with typical =0.25 W/m*K


TLED = 168.3°C - Tmin = 70.92°C


But it can be done in thermo-conductive plastics with intermediate TC-valuesonly. E.g., =5 W/m*K


TLED = 130.5°C - Tmin = 113.4°C

Thermal Measurements

Proof of priciple• In order to determine the effect of different heat conductivities ( ) four different

materials are compared in the same setup.The materials are:

Alu = 160 W/m.KStanyl TC501 = 12 W/m.KStanyl NC160A = 4 W/m.KStanyl TW200F8 = 0.4 W/m.K

• All materials were sampled in plates 80 x 80 x 2 mm and mounted with a 1 W ledon a mcpcb as heat source. The temperature of the led and the temperatureof a point on the substrate at a distance 15 mm from the led were measured.

• In order to assure a good thermal contact between the mcpcb and the fourdifferent substrates a heat conductive paste was applied.

• The substrates could dissipate the heat free to the air by natural convection



Setup


Stanyl® TC501= 12 W/m.K

Stanyl® TW200F8= 0.4 W/m.K

Stanyl® NC160A= 4 W/m.K

Alu= 160 W/m.K


Example Stanyl® TC501


LED temp TC501 plate LED TC501


Results summary


[ W/m/K] T led [ºC] T substrate [ºC]

Alu 160 47.5 42.3

Stanyl TC501 12 54.1 39.4

Stanyl NC160A 4 72.1 42.5

Stanyl TW200F8 0.4 95.0 41.9

Ambient temperature = 23 ºC


Conclusion• The effect of different heat conductivities is demonstrated.• Heat conductivities in the range 4 - 15 W/m.K can be sufficient to design for

thermal management.• Heat conductivities over 20 W/m.K have no significant contribution in boosting

the heat management.


Find out moreDSM Engineering Plastics - Stanyl® TC

For more information or an appointment for personal advice please contact:

Stijn Meijers: [email protected] Segment Manager Lighting applications

mailto:[email protected]

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