Safe to post cure Luxeon?

[Flatscan]

I am working on my bicycle headlight mod (my first Luxeon project ever), and I have some questions about working with AA epoxy.

My heatsink has been constructed from an old CPU heatsink and a piece of copper slab from an art store. In order to maximize mass directly connected to the 2 Luxes, to have exposed fins, and to fit inside the case, I have 4-5 separate pieces of metal to attach together. I have been sanding the interface surfaces in preparation for sticking the whole thing together with AA. I will then pot the BadBoy 500 board to the side of the heatsink (superglue and AA) and the Luxes to the front (AA).

At what point should I post cure (15min at 140F) this whole mess? Is it safe to put the Luxeons in the oven? I have no concept of the heat required to kill a Lux.

 

[shiftd]

flat, i think the best requirements are: no direct heat. use aluminum foil to cover your lux. dunno on the temperature, need to ask someone else for that. but i got one of my lux melted its lens away (well, a bit) bec of overheat and direct exposure.
Dat used oven to post cure his sammiches, you might want to ask him for more info. /ubbthreads/images/graemlins/smile.gif

 

[Rothrandir]

i wouldn't cover the luxeon with anything...wouldn't do a bit of good.

the luxeons can take 140f just fine for a while. my oven can't go any lower than 150, so i bake them at that.

it's an optional step that most people dont' even use (as far as i know), but it increases epoxy hardness and thermal transfer, and that makes it worth it.

basically, dont' worry about it. after it's all done, pop it in the oven and enjoy a scoop of icecream while you wait /ubbthreads/images/graemlins/wink.gif

 

[shiftd]

and make sure you share half of the scoop with roth, or else he might haunt you /ubbthreads/images/graemlins/tongue.gif

but i still think using aluminum voil help the lux from direct heat from the oven /ubbthreads/images/graemlins/icon3.gif
guess everyone has different method.

 

[dat2zip]

I post cure at 140 and 150 all the time with my modules. No problems.

 

[Rothrandir]

shifty, the way an oven works, is by heating the air. putting something over it (particularly something like aluminum foil, which conducts heat) would do absolutely no good at keeping heat out.

for example, go to your oven, and put in a hunk of aluminum foil, and turn it on to 140degrees.
now reach your hand into the oven. the air is warm right?
now touch the aluminum foil...

 

[tylerdurden]

If your piece will fit in a toaster oven, you might try that. Toaster ovens usually will go a little lower than a full-size oven and they don't take so long to heat up.

 

[dat2zip]

Yes, very true. I actually set mine to below 150. Let it stabilize there and then crank it up to 150. The heater elements stay hot long after they turn off and will overshoot severely.

Watch you heater elements if you can. If they start glowing red, and then turn off, you will get an overshoot.