Gold foil to maximize diode-heatsink heat transfer?

[Minamoto Kobayashi]

Hi.
In all my laser portable builds I can see a little gap between the copper diode heatsink and the hole of the aluminum heatsink, and this is certainly a bad issue, especially for the high powered lasers, since the air is not a good heat conductor.
I tried some high quality CPU thermal paste like Prolimatek nano silver, but they works well only under high pressure between the parts, and they aren't electrically conductive, so this is not surely an optimal solution.
So this is my idea: use a thin 24k gold foil around the copper diode heatsink to create enough thickness between the walls to eliminate the gap.
Since the gold is really pliable, I may easy create the required thickness, so the diode will be inserted with a good pressure into the aluminum heatsink hole.
The pure gold is both good electrical and thermal conductor, and never oxidize, so I think this could be the best solution available.
This is the eBay link, the seller is in UK:

Fogli d'Oro Autentici al 100% 24ct Multi Uso - Decorazione | eBay

What do You think about this workaround?

 

[Sigurthr]

If I'm not mistaken they use indium foil for a similar purpose in high end mil-spec electronics. It should work well as long as it is implemented properly, it is just a matter of extra cost.

 

[Minamoto Kobayashi]

Hi!
Yes I know, but usually indium foil is used over a flat surfaces.
Diode copper heatsink has a round shape, and the aluminum heatsink too,
and I do not know if indium foil is easy pliable as the gold sheet, and if it can be wrapped
in more coils ...

 

[Sigurthr]

I wasn't saying you should use Indium, which it is indeed ideal for only flat matings, but I was saying that your idea of using gold should work well!

 

[Photonz]

I'm not so sure about Gold Foil's thermal transfer capabilities but I know it's useful for discovering the existence of dense, charged center within an atom...:crackup:

 

[Minamoto Kobayashi]

Yes, gold has good thermal capabilities after copper and aluminum. And it is more pliable and do not oxydize in the years. I will try to use it in my new builds ...

 

[Photonz]

...^It was a joke about Rutherford's Gold Foil experiment...

 

[Minamoto Kobayashi]

:beer:

 

[Alibekova]

Only slightly off topic, but I have 500 grams of Indium in the form of a bar, it is 999 % pure, does anyone know of a good way to make sheets out of this material or is that something too high tech to do at home?

 

[Sigurthr]

Unless you have a multitonne roller press in your garage... no, there's nothing you can do at home to make a foil out of it.

 

[grainde]

Why dont you use Al foil instead of Au...would be a lot cheaper, much easier to get and would actually work better...:thinking:

There is also an Al sticky backed thick foil, not the common kitchen variety, that you can get from a hardware store. This would also be considerably easier to wrap around your module. :beer:

 

[djQUAN]

I wouldn't use the sticky back version as the adhesive isn't a good thermal conductor and it adds thickness too. Use kitchen foil instead.

 

[grainde]

I wouldn't use the sticky back version as the adhesive isn't a good thermal conductor and it adds thickness too. Use kitchen foil instead.

Thicker foil would be better as you would need perhaps only one layer of foil rather than several. Several layers have air gaps which will inhibit thermal conductivity. Admittedly you could use thermal paste between the layers. :beer:

 

[djQUAN]

Yes, but the additional thickness is from the adhesive which increases thermal resistance.

 

[grainde]

Im not going to bother arguing. Just bear in mind how many layers of thin film will be needed to obtain the same thickness of foil and how many air pockets will have between the layers. Anyway guess testing would be the best way to confirm it. :beer:

Edit: just had a very quick google...:

http://www.abl-heatsinks.co.uk/heatsink/heatsink-pads.htm

http://www.specialtytools.com/categ...scotch-heat-conductive-tape-425-2-x60-yd.html


or even better:

http://www.tapeindia.in/copper-foil-tapes.html

http://www.parker.com/portal/site/P...cat=THERMALLY+CONDUCTIVE+ADHESIVE+TAPES&Wtky=

 

[djQUAN]

No one is arguing. You're correct that one layer of thick foil is better than several layers of thinner foil and I'm not disagreeing with that. My point is that the sticky foil type is thicker but not because of thicker aluminum but because of the additional adhesive layer which is not a good conductor unless ofcourse, you use the thermally conductive type which may have special thermally conductive adhesive