Taken from page 15 of your link :
—snip—
To ensure heat flow from the LED Array to a heat sink, pay close attention to air gaps or voids located between the bottom of the LED Array and the heat sink. Such voids will significantly impede the flow of heat and therefore must be eliminated. The use of thermal interface materials, such as thermal greases, pastes, or adhesives, is recommended to ensure that air gaps and voids are eliminated.
—snip—
If using a paste, the amount of paste that is dispensed should be enough to cover the entire base of the LED Array, but not so much as to result in a thick bond line, which will increase the thermal resistance. Application of excess thermal interface material can also create side fillets. Fillet size should be kept at a minimum and must not touch the top of the LED Array.
—snip—
Your right with the carrier fluid - the silicone oil can bleed out and change the viscocity of the paste but the thermal conductive material stays in place and still does his job.
Anyways in a few years the actual LED most probably will be replaced by something way better/brighter
Also, lots of good youtub vids on proper goop advanced application techniques (where I learned). I think the reason that most of us dont see significant thermal break-down issues with these thermal interface goops is because our computers and equipment become obsolete before the goop has a chance to harden out. In most applications, temperatures are usually controlled via active cooling… unlike what happens in many pocket-rockets. Either way, proper application is critical if your goop is to do a proper job.
This is 4.99 with free shipping for the 4gram. works out to be about 1.25 per gram. about .35 cents more per gram than the original deal (US only free shipping, ships out of Cali)
I agree; it’s quite a bit thicker than Arctic Cooling’s MX-4. I think it’s a bit less viscous than AS-5 though; I’ve tried them side by side, and the MX-2 felt a bit thinner than the AS-5 I’ve got.
JML, I’ve been around since the Luxeon generation where the base of the LED ie the heatsink, was connected to the -ve input. Seoul LEDs had the heatsink connected to +ve. The habit developed was to press the LED firmly onto the heatsink but not so hard that there is electric contact or the LED would fail. I’ve maintained the habbit of pressing the LED or star down onto the heatsink while avoiding twising….
The question. SHOULD I TWIST the LED or star as I press down to remove as much thermal compound as possible? Of course, this must be done for only a few seconds before the epoxy starts to set.
Simple answer YES
The less stuff you put in between the two metals the better the heat will travel and
the best heat-transfer would be metall to metal without anything in between.
Unfortunatly thats impossible even with two brightly polished surfaces because there is
no way to prevent microscopic airgaps. Thats where the thermal compound gets into the game.
Its a carrier fluid filled with tinyest particels of aluminium/silver/whatever that settles in the gaps
and transfers the heat (atleast better than air). See this link from Arctic : Thermal interface basics
Not as important but also interesting is that these particels need a while (depending on composition)
to settle down in the gaps. Some thermal compounds need several hundred hours to work optimal.
So aslong it is electricaly possible press and twist and keep pressing until its almost cured.
If it is possible to solder it than thats better - afterall thats how the LED is attached to the star
and was ment to be attached to any heatsink.
But i just saw that you already opened a new thread about heatsinking - good idea
Theres a lot to learn and to gain by good heat transfer
