# LED Heat sink design guide HELP



## pavithra_uk (Nov 24, 2011)

Anyone know a guide to design/select heat sinks for LEDs ? for 1W, 3W, 5W & 10W LEDs

I have lot of salvaged heat sinks from old P2, P3 computers, power supplies & other electronic equipments. but I don't know how to select heat sink for LEDs

for example, I have heat sink 2" x 2" , 0.75" height finned, 0.075" thick Aluminum. how is it ?


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## David_Campen (Nov 24, 2011)

The easiest thing might be empirical tests. I would guess that the heat sink you mention would work well for a 3 watt LED. Try it, if the heat sink remains cool enough that you can hold it in your hand then it is sufficient for this LED and you could then try it with a 5 watt LED.


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## pavithra_uk (Nov 25, 2011)

David_Campen said:


> The easiest thing might be empirical tests. I would guess that the heat sink you mention would work well for a 3 watt LED. Try it, if the heat sink remains cool enough that you can hold it in your hand then it is sufficient for this LED and you could then try it with a 5 watt LED.



Thanks for reply

Yes I tried it with 3W (Luxeon K2) and remain cool. Now Im gonna try with two 3W LEDS.


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## joday (Nov 28, 2011)

Hi Pavithra:

We've published a guide on LED thermal engineering that can be helpful, it's free, and contains article such as:ATS Case Study: Feasibility Study of an LED-Based Lighting System Using Analytical Modeling

ATS How To: How to Cool High Power LED
Clemens Lasance Lecture on LED Thermal Management: Thermal Management for LED Applications: What is the Role of the PCB?
Clemens Lasance, Michael Gay, Norm Berry, Richard A. Wessel on MCPCB’s for LED Applications: MCPCB’s for LED Applications, Thermal Management Material Specifications
Jeff Hill of Arrow Electronics Video: An Energy Star Compliant Reference Design For LED Light Fixture
Dr. Kaveh Azar Video Interview: LED Heat Sink Types and Applications

Anyway, its free, no salesperson will call, no registration required. Here's the link: http://qats.com/cms/free-thermal-management-led-lighting-resource-kit/

We do alot of work on LED engineering so, if you have a question, post it here and I'll check with our engineers and see if we can get you an answer.

John


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## tonycollinet (Nov 29, 2011)

pavithra_uk said:


> Thanks for reply
> 
> Yes I tried it with 3W (Luxeon K2) and remain cool. Now Im gonna try with two 3W LEDS.



Don't forget to make sure that there is good thermal coupling between led and heatsink. If not, the LED will get stinking hot, and the heatsink will stay cool. Use thermal paste of some sort.


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## Kamlesh Barot (Sep 20, 2014)

Dear Mr. John,

i went through each of the links in your reference Kit. I couldn't find an answer to my issue. Need help for my LED.


I was able to procure after a lot of turmoil, 10 watt - 12000 CCT x 8 numbers white LEDs for my planted tank from Singapore to my home in Bombay. After plastering it with the thermal plaster "Kafuter 5202" on my two heat sinks having 5 fins in nine inch length, had connected four each LEDs on the two sinks. Out of the four LEDs on each heat sink, two are connected in parallel on each heat sink, while the rest are in series joined to a driver matched with the LEDs. 


Out of the two heat sinks, one has 8 x 3 watt - 10000 kelvin LEDs working on them earlier, the new 4 LEDs are in between the square placement of the old LEDs.


After switching the lights on the new 4 LED sink doesn't heat up so much since I have put a small fan above the fins of this heat sink and on the 4+4 heat sink I have put another small fan on one side of the fins inputting the air and a small fan with fins on the other side of the fins to pull out the air.


There is small fan bringing ambient air (30 degrees C) from outside in the box above the aquarium. But the 4+4 heat sink does not dissipate as much heat as the 40 watts new plus the 24 watts old LEDs. It gets too hot to touch.


Please help me where I can change something that these new as well as old LEDs can be put on during the nine hours of the day.


Kamlesh Barot


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