Thermal conductivity of Arctic Silver/Alumina is not great that's for sure. But it is relatively inexpensive and is easy to find in the US. I think that they are fine for flashlights. The key is to apply an extremely thin layer so that you get mostly metal to metal contact with the paste filling only the tiny gaps in between the mating surfaces. That's the idea anyway. Well, it's better than using nothing.
For use with P60 drop-ins you don't need bonding as the reflector should hold the emitter in place. Any kind of non-adhesive CPU heatsink paste would probably work okay. Use the non-adhesive stuff as those are easier to apply a thin layer of. The thing that matters more is the quality of the mating surfaces. The flatter and smoother the surfaces the better to maximize metal to metal contact.
Stay away from thermal tapes and thermal pads. You want metal to metal contact and those get in the way of that.
Almost forgot about this. This stuff is really cool. It’s in the same general ballpark as the Chomerics materials, but it’s easier to get and easier to use…
Yep, we’ve used T405 for securing the ‘Cold’ side of TEC Modules to a “Cold-Sink”. It’s not nearly as thermally conductive as the non adhesive stuff (T557/T777), but considering it’s 2 sided adhesive, it’s pretty darn good.
I use Arctic Ceramique2 for thermal paste, when I don't want a permanent bond and Arctic Alumina Thermal Adhesive for when I want a permanent bond. Seems to work fine. Adhesive, when I don't want to screw down a led star and paste when I do (or in a P60 drop-in).
Today I found a thermal compound accidentally at home for cpu mainboard etc.
And I used it for a Ultrafire 502b with xml u2.
Also used some aluminum foil.
I am astonished by the results. P60 drop-in area gets hot in nearly 5-10 seconds in high mode, the led produces a cooler white light and it is brighter than before!
You think it moves heat well now - try doing the wrap job nicely. All those air gaps SERIOUSLY take away from the thermal transfer ability of the foil. You want a TIGHT wrap.
Also, the thermal paste on the top of the star - completely useless… Good for making a mess, I suppose…
A mess like that in the pictures. You should use the paste to help transfer the heat to something. In your case, at the top of the star there is only air. So you should clean that thermal paste out.
I’ve used some of that Chomerics stuff (not sure what paste, it was a free sample) and it seems to do a good job, but I’m unable to do fine enough testing to tell the difference between that and cheap Chinese thermal paste. Then again, I do lap and polish all my thermal interfaces and screw them together, which probably has a bigger effect on transfer than whatever paste I’m using.
The chomerics stuff is orders of magnitude better than the cheap stuff. We tested dozens of thermal interface materials and the difference between the good stuff and the cheap stuff is astounding. That said, you’re very correct - the best thermal interface would be one lapped so cleanly that it didn’t require paste. If you’re getting good atomic/molecular level metal->metal contact, the paste becomes pretty irrelevant.
If you’re looking for regular (non adhesive) thermal material - I seriously suggest taking a look at that Aavid Ultrastick that I linked to. It’s really awesome, and far less messy than most thermal ‘stuff’… Very reasonably priced (One stick goes a LONG way) and very easy to get (Mouser, Newark, etc).
Yes, I missed that. We deal with these vendors at work - for the UltraStick, Mouser has stock for $19, Newark has a lead time of 113 days (?) - something wrong there, Digi-Key also has no stock but at $43. Arrow has a listing for it, but no price, looks like no stock.
I’ve absolutely no doubt it is superior, I just don’t have any reproducible way of quantifying any difference between it and the cheap stuff. It does its job and I’m happy with it, even more so because it was free and will last me a considerable amount of time
