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Finding an appropriate heatsink for 5V 3W LED? Answered

Hello, I have bought some 3W 5V leds, and now I have to dissipate the heat they produce. I am thinking of using an xbox 360 GPU heatsink i have laying around (


), cut in apprpriate size. Then I would glue the led with thermal epoxy to it. 

Can somebody suggest an adequate size for the heatsink? I can't find any info around. I have other heatsinks as well, I would rather not buying a LED heatsink if that's not mandatory.

Thanks in advance :)

Picture of the leds attached, they have no board to screw them with.



I'd not glue them on, I'd use screws and heatsink compound. The cooler you keep the LEDs the longer they'll live.

Do you think thermal compound is not enough to ensure a good heat transfer? I can' use screws, the leds are without board.


I've had good success with these things mounting them on 30x 30mm PCB squares, with a little thermal compound under them

What kind of PCB did you use? The star-like most high-end Cree leds use?

The crees are using aluminium substrate material, which isn't easy to get as an amateur. I just used plain FR4 for these little LEDs. If you're making real boards, then you can put a load of vias through around the LED into the layer on the back, and get improved cooling performance.

All right, ordinary boards seem just the right way to go. So I can just use a spare circuit board with some thermal paste under the LED, right? Thank you for all the help!

Do you think that just the PCB is enough to keep it cool? I don't think so but I assume I would able to screw the pcb on the heatsink then.