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Graphite foam cools hi-intensity LEDs

8/30/2010 08:03 PM EDT
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jg_
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re: Graphite foam cools hi-intensity LEDs
jg_   2/14/2011 9:53:39 PM
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[" which have been estimated to exhibit thermal conductivity greater than 1700 W/mK (2300 W/mK at cryogenic temperatures) as compared to copper at 398W/mK."] Copper is now far too costly, and Al is also energy intensive. [" A finned heat sink made from graphitic foam can be up to 3 times more efficient than one made of Al "] I see Carbon Foams are electrically conductive, which is a problem, but maybe they can manage a large area insulation step ? The holy grail would be high thermal conductivity _and_ electrical insulation.

docdivakar
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re: Graphite foam cools hi-intensity LEDs
docdivakar   9/21/2010 9:12:32 PM
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I suppose this is the next best thing compared to CVD Diamond as for heatsinking. I would like to know more about reworking and (also pointed by @hm) physical behaviour over time. @RoboticDeveloper, the ThetaJ(x) numbers can be estimated from the thermal conductivity numbers already published. Are you looking for the JEDEC-defined (1ft cube) numbers? @Kinnar, the industry has used graphite's superior properties before, though not to the scale I would like to see. StableCor is one such material that is used in PCB cores and a number of power electronics companies use it. Dr. MP Divakar

Sanjib.A
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re: Graphite foam cools hi-intensity LEDs
Sanjib.A   9/8/2010 5:05:10 PM
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That is excellent then! Thanks for responding with information I was looking for. How does the cost compare with the Aluminium heat sink? Must be expensive, correct?

agk
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re: Graphite foam cools hi-intensity LEDs
agk   9/8/2010 11:37:28 AM
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Hi hm Max op temp in air is 500 deg C for the ORNL graphite foam during experimentation when compared to Aluminim 6061 is 600 degC.

agk
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re: Graphite foam cools hi-intensity LEDs
agk   9/8/2010 11:32:02 AM
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Hi Sanjib Graphite Ligament Thermal Conductivity 1700 W/mK Apparent bulk conductivity 180 W/mK Low CTE -~2 -4 µin/in/°C Excellent thermal management material This is 3 to 5 times more efficient compared to Aluminium More technical information available at poco graphite website www.poco.com

_hm
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re: Graphite foam cools hi-intensity LEDs
_hm   9/1/2010 4:05:28 PM
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Many applications can take advantage of this material. Is this material RoHS compliant? If it is employed in product, will product be green and can be exported to EU market? What is the maximum operating temperature for this material? If it is exceeded in normal operation, will it permanently damage and change its heat sink property drastically?

Robotics Developer
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re: Graphite foam cools hi-intensity LEDs
Robotics Developer   8/31/2010 3:43:44 PM
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I am thinking that this will be great for the energy savings and lowered maintenance costs. The early failures of LEDs due to heat my explain why the almost brand new LED street lights in my town have failed LEDs at less than a year old. It would be nice if the article gave a little more detail like the ThetaJ numbers of the material. Thanks for an interesting bit of hot news.

Kinnar
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re: Graphite foam cools hi-intensity LEDs
Kinnar   8/31/2010 2:09:15 PM
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The world has got a new heat sink, this can be used for other applications as well. Simultaneously it is a very good news for domestic and industrial lighting as well as for energy conversation. Going towards green earth..

daleste
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re: Graphite foam cools hi-intensity LEDs
daleste   8/31/2010 1:41:20 PM
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This new technology for heat sink is great, but it would be better to increase the efficiency of the LED.

Sanjib.A
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re: Graphite foam cools hi-intensity LEDs
Sanjib.A   8/31/2010 1:04:28 PM
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Yeah! It is great to know about this graphite foam heat sinking technology. I understand from this article how this could be very useful for heat sinking the high-intensity LEDs. Can this also be used for heat-sinking the chips on board, as an alternative solution to the aluminium/copper heat-sinking? It is mentioned in this article that the conductivity provided by graphite foam is superior to that provided by the metal heat-sinks. What are the other advantages / drawbacks of graphite foam vs. aluminium/copper heat sinking methods?

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