These are about nickel sized coins but they also have one ounce coins about 30.6mm in diameter and2.6mm thick. It wouldn’t take too much effort to lap these perfectly flat and have pretty much perfectly pure copper heat spreaders. If you can manage to solder the dies directly to these I know they’d be able to suck the heat from the dies as effectively as possible.
For the nickel size at a little over 2 bucks a piece they’re worth it, plus you get some nice collectible coins out of it too. The one ounce ones are especially beautiful to have even more so when you polish them up.
A friend of mine bought a cheap Chinese clone of this Trustfire Z5
While the host was well machined, the screw in pill was horrendous.
It was completely hollow, with the X-ML LED star sitting on about .25mm of it’s outer edge (virtually ZERO heatsinking capacity)
So what we did was machine a Copper disc on the lathe about 2mm thick and press fit (very tight fit) it into the hollow pill so the LED star can sit directly onto the copper disc.
We lapped both the copper disc and the back of the LED star to a mirror finish with the help of a completely flat polishing stone to ensure good contact across the entire contact area.
We applied good quality thermal compount between the LED star and the copper disc.
For test purposes, to ensure sufficient heat transfer was as expect, we ran an X-ML LED at 5 amps direct drive using a power supply.
Heat transfer through the body of the torch/flashlight was pretty much instantaneous. The body became uncomfortable to hold after about 3 mins of runtime.
We stopped the test after about 5 or 6 mins and were happy that the modification was a success, as we knew that we could easily run 3-3.5 amps into the LED without worrying about insufficient heat transfer in the future.
For people with Cree LEDs on stars and a DMM, check the base of your stars for electrical conductivity… There is none right? Can I assume that the base of stars are anodized? IDEALY, wouldn’t it be best to remove this anodizing? PRACTICALLY, how do I go about removing the anodizing. (I intend to use sand paper with a final grit size of <2000)
Nor have I. All the stars that I have are bare aluminum. Does that mean anodized or chem-filmed stars don’t exist? no - I’ve just never seen one.
Even if it were anodized, the anodic coating is so thin *see_note that it will have very minimal effect on thermal transfer. Using better thermal interface material or applying more pressure on the star/pill junction would have far more effect on thermal transfer than sanding off the coating.
PPtk
For instance, on 6061-T6 Aluminum, MIL-A-8625 specifies a minimum thickness of 0.000099” (.09 thousandths of an inch) for Class II coatings. That is the minimum thickness, but the coatings are generally not much more than the minimum.
