How can i solder Cree LEDS? Heeelppp

[cdrov]

Hi there, i have just got 20 Cree Leds that came without being soldered to anything (bare Led). As i see the led has the power leads at both ends while at the middle is a square surface probably for heat dissipation (The LED looks like this --- I [_] I ). So here's the question ... Should i solder this surface (which is behind the led) to the board or is is just enough just to put heat dissipant silicon? Since soldering seems impossible under the LED

 

[LukeA]

You have to destroy the traces through the substrate that go from the bottom contacts to the top contacts. A dremel works nicely.

 

[saabluster]

Hi there, i have just got 20 Cree Leds that came without being soldered to anything (bare Led). As i see the led has the power leads at both ends while at the middle is a square surface probably for heat dissipation (The LED looks like this --- I [_] I ). So here's the question ... Should i solder this surface (which is behind the led) to the board or is is just enough just to put heat dissipant silicon? Since soldering seems impossible under the LED

What "board" are you using to mount the LED to? What current will you be running it at?

 

[shakeylegs]

Here is one thread that discusses soldering crees
http://www.candlepowerforums.com/vb/showthread.php?t=178772
And here is one that describes the polarity of the emitter
http://www.candlepowerforums.com/vb/showthread.php?t=158649

 

[Nitroz]

Hi there, i have just got 20 Cree Leds that came without being soldered to anything (bare Led). As i see the led has the power leads at both ends while at the middle is a square surface probably for heat dissipation (The LED looks like this --- I [_] I ). So here's the question ... Should i solder this surface (which is behind the led) to the board or is is just enough just to put heat dissipant silicon? Since soldering seems impossible under the LED

It works best if you reflow solder the LED to a board and then use some artic silver to attach that to a heat sink if needed. If you plan to attach the led and need to isolate the bottom, make sure that you remove the bridges at the corner of the LED. The best way to do this is file or gring them off to the dot on the bottom of the LED corner.

 

[cdrov]

Thank you all for your help, now i can hope i might solder them. I am thinking of using either a waffer for electronics with copper on the conductive side which seems to be the cheap solution or a double sided wafer where the back side has aluminium (like the stars used) which is a little more expensive. Of course then i will pt them on a bigger aluminium heatsink while I intend to have them running at around 400mA probably with 7,2-7,4 Volts in two rows.
Moreover since my english is not the best i did not understand the "reflow solder the LED to a board"... Regards