Removing LED from MCPCB / non-permanent mounting of LEDs to heatsink

[chris_m]

I want to do some testing with the SSC P4 emitters I've got - specifically to see how they perform with the optics I've got that are designed to work with SSC P3 LEDs. However in order to test them properly I need to mount them on a heatsink, which isn't that straightforward with emitters which you want to later remove to mount in a proper light. Fairly straightforward with stars though, as you simply bolt them down.

Having got that far with my thoughts, I realised that I have some Seoul star bases already - attached to some P1 LEDs that I bought a while ago. Since I'm probably never going to use these LEDs seriously in a light, I wondered if it was possible to remove the LEDs from the MCPCBs in order to mount the P4s on them.

Has anybody ever removed factory mounted (as these are) LEDs from a MCPCB? Since I'd imagine experience with SSC LEDs is rather limited, I'm also interested in experiences with Luxeons. Are the LEDs soldered to the MCPCB, and if so, any suggestions on how to remove them? Do I just stick them in the oven for a bit?

Alternatively any other suggestions on non-permanent methods of mounting emitters to a heatsink? I should note that the lens I particularly want to test is a triple, so I need 3 LEDs properly aligned (and already have a h/s drilled to take stars in the appropriate positions).

 

[chris_m]

Somebody here must have removed LEDs from stars?

 

[Gryloc]

Chris_m,

I have found a good way that doesn't destroy the board or the emitter. Both the emitter and board is still usable. All you need is a sharp knife, like an ex-acto hobby knife. At a very low angle to the aluminum hex board, get the knife edge wedged in-between the board and the slug of the emitter. Carefully put a strong forward force on the blade and if you do it right, it will simply pop off. Be careful not to pry with the knife or twist it. With most of the older Lumileds emitters, the LED emitter will actually separate and it will be destroyed. You will actually rip the plastic body and dome from the slug and emitter. So, when you press in the way I mentioned, you are actually putting a strong shearing force on the emitter slug which pops it off.

Here. I thought it would be helpful to sketch up a picture based from Lumiled's spec sheets. Click on it for a bigger image...


After you separate the two parts, just scratch the surface lightly with your knife to remove the old epoxy material. Just make sure it has a smooth(-ish) and clear surface for the new layer of thermal epoxy or thermal paste.

I used this to remove several emitters from their epoxied place. I found it worked recently because I wanted to fit a SSC P4 emitter onto the existing hex board that was in my ProPoly 4AA flashlight. Well good luck and keep us posted with your results!

-Tony

 

[Anglepoise]

Chris,
For testing raw emitters, this is what I do.

Get an old computer heat sink. Make sure it is black anodized aluminum.

The anodizing will not conduct electrical current.

Then I went to the hardware store and purchased a roller kit for an aluminum sliding patio door. These rollers have a nice 2 inch long by 1/4 inch wide piece of spring steel. I drilled out the rivet so I now have the flat heat sink and 2 pieces of spring steel. I carefully lay the emitter on the heat sink and place each spring so it just on top of the brass contacts on the emitter. The spring steel pieces are held secure with those small black plastic clips. ( Halfords ??)

I run a wire from my power supply to each spring piece.

This emitter is held flat against the heat sink and the two clips keep everything together while one does test with reflectors, output , whatever.

This works equally well with LUX, XR-E, and S-P4 emitters.

Good luck