Thermally conductive plastics in LED lamps - dsm.com

Stanyl® TC

Thermally conductive
plastics in LED lamps

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

Copyright © DSM Engineering Plastics 2010

DSM Engineering Plastics - Stanyl® TC DSMUnlimited.

Thermally conductive plastics

LED is the lighting solutions of the future. Current lighting
applications are designed with this new LED technology.
Stanyl TC is the best long term solution offering
productivity gains, resulting in energy savings, coast and
material reduction.

Copyright © DSM Engineering Plastics 2010

DSM Engineering Plastics - Stanyl® TC

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 been
developed. They allow LED bulbs to be substituted for incandescent, halogen
or fluorescent bulbs in existing lighting infrastructure.
The significant benefits of LED Lighting – energy savings, longer life, higher
efficiency and reduced environmental impact – as well as new legislation are
encouraging consumers to replace conventional lighting lamps with high-
power LED lamps.

DSM Engineering Plastics - Stanyl® TC

Stanyl TC in LED applications

Trends: Energy saving and extended Philips Master LED lamp
Application: lifetime in lighting solutions
Features:
High energy efficient
Eco+: LED lamps

Thermal conductivity,
design freedom, high
productivity

Aluminum replacement,
Productivity gains,
energy savings and
material reduction

DSM Engineering Plastics - Stanyl® TC

Thermally conductive plastics
When are they of use?

Plastics are thermal insulators
with typical conductivities

polymer 0.2 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

DSM Engineering Plastics - Stanyl® TC

Thermally conductive plastics
When are they of use?

Measuring the thermal conductivity
If we measure the thermal
conductivity of Dyneema® ropes, i.e.,
Moleculary aligned UltraHigh
Molecular Weight Polyethylene,

polymer 45 W/mK [1D] is obtained.

DSM Engineering Plastics - Stanyl® TC

Thermally conductive plastics
When are they of use?

In metals and crystalline ceramics,
vibrations can transmit efficiently
in 2D or 3D

Therefore, Metals, ceramics have TC

values metal 100 W/mK.
ceramic 1 100

We rely on fillers to make TC-plastics.

DSM Engineering Plastics - Stanyl® TC

Thermally conductive plastics
When 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]

1 AB 2 2
11 B 2

A 2L
D

B 2/ 1 1
2/ 1 A

1 1 2,max
2
2,max

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

DSM Engineering Plastics - Stanyl® TC

Thermally conductive plastics
When are they of use?

Filler particle aspect ratio L/D~15:

DSM Engineering Plastics - Stanyl® TC

Thermally conductive plastics
When are they of use?

Improved filler with much
higher aspect ratio:

Conclusion:
best we can do in thermally
conductive plastics is

20W/mK, which is well
below 100W/mK for
metals and ceramics.

DSM Engineering Plastics - Stanyl® TC

Thermally conductive plastics
When are they of use?

Does this mean that
metal replacement is
not an option?

Heat source Convective cooling
or metal contact
q in

x=0 x=d

T 2T x=0: q in T
cp t tx0

x2 T h (T x d Tair )
xx d
x=d:

DSM Engineering Plastics - Stanyl® TC Convection
limited
Thermally conductive plastics
When are they of use?

No it doesn’t:

In a convection limited
situation, one can lower
(=replace metal) without
increasing part
temperatures. Just look for
the right applications.

Conduction

T q in d limited

DSM Engineering Plastics - Stanyl® TC

Target application: LED lamp holder

Plastics for the lamp-holder

Lamp holder Not: package material.
needs thermal
conductivity. Package material needs to have high
reflectivity + retention of reflectivity.

DSM Engineering Plastics - Stanyl® TC

Target application: LED lamp holder

Why? Because LED is future in lighting

DSM Engineering Plastics - Stanyl® TC

Target application: LED lamp holder

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

Light output [%] Useful life of high brightness white LED at different operating temparatures

100

T junction = 63 C

90

T junction = 74 C

80

70

60 2 y 6 y

50 10000 100000
1000 Time [hours]

DSM Engineering Plastics - Stanyl® TC

Target application: LED lamp holder

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

TLED = 125.7°C - Tmin = 115.1°C

DSM Engineering Plastics - Stanyl® TC

Target application: LED lamp holder

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

TLED = 168.3°C - Tmin = 70.92°C

DSM Engineering Plastics - Stanyl® TC

Target application: LED lamp holder

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

TLED = 130.5°C - Tmin = 113.4°C

DSM Engineering Plastics - Stanyl® TC

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.K

Stanyl TC501 = 12 W/m.K

Stanyl NC160A = 4 W/m.K

Stanyl TW200F8 = 0.4 W/m.K

• All materials were sampled in plates 80 x 80 x 2 mm and mounted with a 1 W led
on a mcpcb as heat source. The temperature of the led and the temperature
of 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 four
different substrates a heat conductive paste was applied.

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

DSM Engineering Plastics - Stanyl® TC Stanyl® TW200F8

Thermal Measurements = 0.4 W/m.K

Setup Stanyl® NC160A

Stanyl® TC501 = 4 W/m.K

= 12 W/m.K Alu

= 160 W/m.K

DSM Engineering Plastics - Stanyl® TC LED TC501

Thermal Measurements

Example Stanyl® TC501

LED temp TC501 plate

DSM Engineering Plastics - Stanyl® TC

Thermal Measurements

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

DSM Engineering Plastics - Stanyl® TC

Thermal Measurements

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.

DSM Engineering Plastics - Stanyl® TC

Find out more

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

Stijn Meijers: [email protected]
Global Segment Manager Lighting applications