Bonding Luxeon Stars to heatsinks

In the past I've been able to either bolt the Luxeon on to the heatsink or at least press it firmly against the heatsink to get a good thermal contact.

Unfortunately space is limited in my latest project, although I'd still like to run stars (because I have a couple laying around). So, I've decided to bond them on. (No real biggie I hear you say...)

Well first off I was just going to epoxy them on, but I've since realised that I might want to get them back off again later, which makes things a bit trickier. What's the best way to do it?? /ubbthreads/images/graemlins/help.gif

I've thought about thermal tape, but I'm not really keen on the idea, but what about a mix of thermal paste and some kind of epoxy or glue?? Has anyone got a secret recipe??! /ubbthreads/images/graemlins/poke2.gif

Cheers, Dave.

If you use Arctic Alumina 2 part thermal epoxy, it is fairly easy to use a sharp blade to pop the star off the heat sink when you need to. The stuff works pretty good, but it's not like "2-ton" or JB Weld. I've removed quite a few AA bonded stars and emitters without a problem. I guess what I want to say is AA bonds well, but doesn't stick like real epoxy.
Rob

Hi Dave,

Welcome to CPF! /ubbthreads/images/graemlins/wink2.gif

Artic Alumina thermal epoxy, is the simplest solution for bonding emitters/stars to a heatsink.

Here's a link to another discussion about epoxies.

Cheers, thanks!! I've been a Lurker for over a year now, so I thought I'd better sign up and try and make a contribution!!

Thanks for the Link, search wasn't doing me real good earlier....

Yeah, I don't need anything super strong, just enough to hold them, although they will have to put up with a fair bit of vibration.

Cheers, Dave.

So am I better off putting a dab of epoxy on top of the star/heatsink while pressing the Star against the heatsink and letting it set, or putting some between the heatsink and the star?

Cheers, Dave.

a curiosity.... if you want good thermal conduction as well as possibility of removal later... what about a dab of artic silver in the middle for conduction with 6 dots of epoxy of almost any kind on the cornersof the star... than you'd have the best of both worlds... best thermal conduction and easier removability.

I used artic silver adhesive on my project with emitters to aluminum heat sink and couldn't be much happier... they were a bit tricky to get them to settle in, they wanted to float, but the solution i had was to put a card on top of the three emitters and about 4oz weight on top of the card.

Just I have an idea but did not try, yet.

Thermal conductive tape from 3M.
-Part number 9890
-Thickness : 0.25mm ( 10 mils.)
-Temperature :
Short run : -55~260 degree C
Continuous run : -35 ~90 degree C

Is there anyone who tried this ?

Arctic Alumina thermal adhesive.

Remember to get the adhesive layer as thin as you can between the base of the star and the heatsink, shoot for about the thickness of a piece of paper (0.002 inch) as the thickness of the adhesive layer. Thinner is better (thermal adhesive or compound is much better than air at conducting heat, but it is still much worse than heat sink metal /ubbthreads/images/graemlins/frown.gif ).

If you want to go nuts about it, lap the base of the star and the top of the heatsink to one another to really get the surfaces close together. /ubbthreads/images/graemlins/crazy.gif

Thanks for the replies!!

MoonRise - I might just end up lapping them yet, I just did my CPU and heatsink the other day!! I want to at least remove the annodizing from my heatsink, and I might as well do the Stars while I'm at it. Looks like I'll have to look for some Arctic Alumina then!!

Cheers, Dave.