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Anyone ever try melting a copper plate into an aluminum heatsink?

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Szech

Member
Joined
May 1, 2001
Location
So-Cal
I'm taking metal shop this quarter, and I was thinking about doing exactly this. The victim? My Thermaltake Volcano II. My plan is to cut off a good chunk of the heatsink's existing base and lap it. I will then lap a copper plate that is the same thickness as the aluminum that is cut off.

As for attaching it, I figure copper has a higher melting point than aluminum, so if I align the plate on top of the heatsink, and set a torch to 1220F (melting point of aluminum), and heat the copper plate, then it will melt the aluminum underneath, and it will form a metal-to-metal bond.

Seems that everyone's doing it (Alpha, Taisol, Thermaltake, blah blah blah)... And if I screw it up? Who cares?! It was $13!

Your thoughts?
 
W

William

Guest
well the copper is probably going to oxidize if you melt it like that, and that will ruin your copper.
 

Murphy

Senior Member
Joined
Dec 18, 2000
Location
Amsterdam, the Netherlands
Seems like a great Idea to me, it's totally new. Sanding off the copper will deal with it, but won't the aluminium oxidize? You should be really carefull with mixed metals/oxides at these tems. When you mix aluminium with iron rust (ironoxide), you have an VERY EXOTHERMIC mixture, called thermite, which will burn at 1500°C! Don't know how this is for cupper.
Thermite is ignited by heat of a torch or something. It was used to melt through steel or connect railtracks.

So be sure you don't get too much oxide near the aluminium. Good luck with the project!

Murphy
(student chemistry)
 

Caravan

Registered
Joined
Apr 16, 2001
I could be wrong, but A LOT of new coolers that are comming out have a copper base on them. They don't seem to be coroding. How do they attach them if it weren't by means like these?
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
The two metals have considerably different melting points. I'd bet that if you pour molten copper into or onto aluminum, it will burn through it before it has a chance to solidify. Just my gut feeling on it.

Hoot
 

aug1516

New Member
Joined
Apr 22, 2001
He brings up a good point though, many other hsf's out there, such as the Alphas, have a copper base attached. How would they attach it to prevent these problems?
 

Sony

Senior Lighting Designer
Joined
May 2, 2001
Also when you weld or melt Aluminum it you have to wear a respirator because aluminum welding or melting gives off toxic fumes which can cause respatory problems or kill you!!! :(:(
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
aug1516 (May 05, 2001 08:01 p.m.):
He brings up a good point though, many other hsf's out there, such as the Alphas, have a copper base attached. How would they attach it to prevent these problems?

My guess is that they mill the aluminum to accept the copper insert, to very close tolerances. Then they probably cool the copper to shrink it and put it in the milled out area. Once it warms, it is stuck in there pretty good. Some manufacturers drill and screw them on. Some rivet them on. In any case, the fact that there is are two distinctive plates mated up against each other and regardless of hte finish and whether they use some thermal interface compound, you have a thermally resistive junction to add to the equation. That, having been said, I think there is great merit anyway in aluminum heatsinks with copper heat spreaders. Way back when, I took a 60mm cold plate, lapped it to mirror finish, did the same with my old FOP-32 and mated them with A.S. in between. It lowered my temps about 2C at load using the stock YS-Tech fan.

Hoot
 

Caravan

Registered
Joined
Apr 16, 2001
I did the same thing with my aluminum waterblock. and got about the same results. (lapped, A.S. on both sides.
 

AnonymousDude

Disabled
Joined
Dec 17, 2000
I tried using electrolysis to put a copper layer ona heatsink. I ended up with a copper gunk on it. I thik I needed a much lower voltage, like 0.1volts.
 

Phil

Senior Member
Joined
Jan 13, 2001
Location
Bolton, UK
with the copper inserts they impact them into the aluminium heatsink with extreme force, similar to how taisol cold forge their heatsinks I think, it is really hard to melt copper and most of it turns to gas I think, this is why copper heatsinks are made either by soldering the fins on, by cutting out the fins from a block or just wedging them in place (like the hedge hog), silver on the other hand isn't that hard to melt so it would be easier to do what you sugest with this
 
OP
S

Szech

Member
Joined
May 1, 2001
Location
So-Cal
Very interesting... I think I will go the route of arctic silver though, as it seems to be the simplest solution.
 
W

William

Guest
thermite? i think it is thermit, but I would worry to much about this happening, you have to have about even quantities of both to happen. I have seen this expirement, and anything that ends up with molten iron in the end and throws aluminun oxide shrapnel everywhere is very very cool! More to the point. Melting copper will oxidize everything that is exposed to air, so even if you sanded of the top layer, you would have the black gunk(that is what CuO looks like) everywhere in your solution. The same would more than likely go for aluminum. I don't think copper would go to a gas so easily and would not be too woried about that hapening. I think the best bet is to just buy an all copper heatsink as they are reasonably priced and go from there!