Gettin greasy ...

[Snowman]

Just want to let everyone know I came to this thread, I learned, and I now.... still hate chemistry with a passion for some reason. Love algebra hate chemistry which is probably a/b(t*y)% algebra anyway.

[x88x]

Gotta love AMD (er ATI) for keeping it simple!

I wonder if Intel's sloppy IHS's are endemic in the industry, if so then it's obvious why AMD/ATI have eschewed them.

I believe all modern CPUs use IHSs, even AMD. I think the reason they're not used on GPUs (iirc, nVidia doesn't use them either) is because the chip itself is so freakishly huge that it already has plenty of surface area to contact the heatsink, whereas with a CPU the chip itself is quite small and the IHS serves to increase the contact area with the heatsink.

[Edit]
Looking more closely at that sexy pic ... are the large solder fillets on the edges of the die intentional? Do they cover up incredibly small wire leads?

Like SXR said, it's just TIM; those chips are actually surface-mount with all the contacts on the bottom of the chip.

[Trace]

All moderon CPUs from AMD and Intel use IHS's. Not sure about Sun, IBM, etc chips, and yes, nVidia (last I checked) does not use IHS's probably due to what x88x said...Freakishly HUGE chips.

Also, extra TIM

[Kayin]

Most chip companies use an IHS, simply to cut down on returns. If it runs 10C cooler, but you get a 30% OEM return rate, nobody cares.

[mDust]

Note that removing the IHS will cause most current Air Coolers to not properly clamp to the CPU any more. This is because of the space the IHS fills between the die and the cooler. The result will be less than the recommended clamping pressure.

I was thinking about this as well, and it's easily avoided by milling the edges of the HS base to fit within the socket cover. Though cracking the die itself is a possibility, I would expect one to be extremely careful with a several hundred to thousand dollar chip.

I'm asking because pyrolitic graphite isn't expensive in small wafers, but larger chunks get costly pretty quick. ... I'm assuming this stuff (plus 1-2 layers of good TIM?) will be significantly superior to mystery solder plus aluminum/copper IHS. Can't tell yet what the surface is like, if it can be smoothed/honed or it's rough.

Any thoughts on some kind of machined nubs which use a Lego-inspired processor/heatsink interlock? Assuming machinist (or even Lego) tolerances for flatness/etc ... wouldn't it actually slightly increase total direct surface contact area? I suppose thermal expansion might be an issue (parts might "stick" when too hot?), but I really don't know if it'd be a factor within these temp ranges, especially if things are clamped.

So you're planning on risking a thousand dollar processor to replace the copper IHS with a slightly more conductive material? It's not worth it. Mill an air cooler or waterblock to fit directly on the die. The less layers the heat has to travel through, the better. As for the 'lego' design, there would be absolutely no way to effectively apply a TIM to that surface, so you'd end up with a net effect of less efficient heat transfer. If you were machining a part to mate flush with another, it would be much easier to minimize tolerances by making them completely flat rather than any other shape.

[slight thread jack]
In my own bid for a new TIM, would it be possible to ionize atomized copper powder so the particles mostly repel each other thus filling any air gaps? The powder could be suspended in a fast evaporating liquid that essentially leaves a 'solid' copper film between the parts. This would be incredibly hard to store for any amount of time, I'm sure, but it might be feasible to whip up a batch the day of the processor installation.
[/slight thread jack]

[Konrad]

Shows what I know

Well, obviously a superior TIM is the way to go on GPU ...

[Konrad]

@ mDust

Your savage debunking of my wild lego-block idea sadly makes perfect sense. Simple flats are better than interlocks. I can see some arguments promoting perfectly mated curved surfaces since they'd have more surface area than flat, but I think the better perspective (assuming same metals on IHS and HS) is to remember that the only practical effect of these curves or interlocks or whatever is to increase the surface area (and air gaps) of the inefficient TIM layer within the otherwise homogenous thermal block.

Not sure how your ionized copper idea would work. How would you prevent ions from interacting with electronic circuits? Wouldn't an ionized metal be highly corrosive? If exposed directly to the die then condensation might become an issue. If not exposed directly to the die (ie, used within a sealed vapor-phase loop cooler) then you'll need something else to act as the TIM. Just my thoughts.

[mDust]

@ mDust
Not sure how your ionized copper idea would work. How would you prevent ions from interacting with electronic circuits? Wouldn't an ionized metal be highly corrosive? If exposed directly to the die then condensation might become an issue. If not exposed directly to the die (ie, used within a sealed vapor-phase loop cooler) then you'll need something else to act as the TIM. Just my thoughts.

It wouldn't come anywhere near any circuits. Potentially corrosive? Yes. Condensation? Possibly, but I doubt it. Under normal circumstances if the liquid is evaporating, it's not going to be condensing at the same time.
Ideally, the copper powder would be sandwiched between a copper IHS and a copper base-plate of the HS. As the liquid evaporates it floats away, never to be seen again. It would be like a fraction of an oz so it shouldn't take too long to evaporate away and 'cure'. Maybe a day or two of operation?

[Konrad]

It seems a bit bizarre to me. A continuously eroding heatsink? I understand phase cooling, and I accept that some kind of liquefying copper process might be possible below the normal liquidus/melting range for copper (~ 830-1080C). Obviously you're not talking about a molten copper heatsink, just one where copper ions are continuously flowing away like a liquid (and presumably taking a lot of heat with them) ... how? Using excitation of lasers or voltage pulses to stimulate the exposed copper? Using MHD to cycle the "liquid" ions away? I'll admit I don't quite understand your concept. Not saying it can't work, just saying I don't understand it.

[Edit]
It occurs to me is that all this reduction of copper will result in another problem. Either a vacuum is created, or something else (probably air) fills the volume of the displaced copper. I would suspect that air would be uncooperative and insist on coating as much copper as it can with oxides. An oxidizing reaction would produce (a lot of) it's own heat while converting copper (both the ions and the metal base) into nasty thermally inefficient patina.

[Trace]

No. He wants to suspend the copper atoms (ions) in a liquid (water, or such) and apply it like a TIM. Then the water would evaporate, leaving just copper filling the gaps.