Does your heat sink have any fins on it?  Sounds like you are just
describing an aluminum plate.  Fins equal much more surface area which will
do a much better job of cooling the LED.  There are also much better heat
sink greases, but they won't make a lot of difference without an adequate
heat sink.

Brian Kraut
Engineering Alternatives, Inc.
www.engalt.com

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
Of Andre Abelian
Sent: Monday, October 01, 2007 4:56 PM
To: Microcontroller discussion list - Public.
Subject: [EE]: Luxeon K2 heat problem


Hi to all engineers,

I am testing Luxeon K2 1500 ma 3,6 v led no matter what I do
it gets real hot 50 degree C in 30 minutes this is what I do.

1. I use constant current module 700ma 3,6 v " I am giving half power"
2. 1,5 x 1,5 x 1/4 thickness piece of aluminum
3. I used white compound grease in between heat sink.

when I talked to future electronics engineers one guy said it is not
suppose to get that hot then other said the heat sink should be 3 times
bigger then today some one else said what I use is very bad heat sink.
My question is does any one used K2 leds and know how to dissipate
heat? I want to use 3 of them in 3-4 inch round aluminum heat sink.
The thickness can be higher if I needed. any info will appreciate.


thanks

Andre

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