could you use a laser to lap a heatsink?

Crash893 · Mar 24, 2003

i heard on the news that they devloped this machine to laser glaze railroad tracks to make them ultra smooth to reduce drag on rail cars

i was wondering if you could in theory flash melt the to 1/10000 of an inch of the hsf and have it cool smoother than it was?

Crash893 · Mar 24, 2003

http://www.techtransfer.anl.gov/highlights/9-2/laser-glaze.html

blackhabit · Mar 24, 2003

interesting but who has a lazer?

Crash893 · Mar 24, 2003

im just wondering if it could be done

Since87 · Mar 25, 2003

The high thermal conductivity of copper makes it difficult to heat a small portion of it to melting. Steel has much lower thermal conductivity, making this much more practical.

Lasers are commonly used for cutting sheetmetal like aluminum, but only very thin copper can be cut this way. because of how quickly the heat spreads.

RadRacer · Mar 25, 2003

What about casting? I read an article online about using a microwave to melt metals (its no joke, it can be done, but that doesnt mean you should go sticking forks in your microwaves just grins). If you were to melt copper in an open top crucible (say 1" diameter) you should be able to get a perfectly flat surface. Oh well, just a thought.

I don't think lasers would work too well. Copper is a very soft metal and would probably deform under the heat because the heat spreads out so quickly

cV · Mar 25, 2003

You could do it with quick successive passes and some serious heatsinking on the copper, but making it so smooth would be pointless because A) there would be no unevenness to grip the CPU and facilitate contact and B) tarnish would more adversely affect performance.

C) It would be way too costly even for HS corporations to implement on a mass scale.

Crash893 · Mar 25, 2003

i dont think it would cost that much

you would just need a few highpowered lasers

if they can do it to miles and miles of railroad track then it can tcost that much

im not entirely sure what you mean about "1) there would be no unevenness to grip the CPU and facilitate contact"

you want cpus and hsf to be as flat as possible so tehre is more surcface to surface contact to excange the heat

SpliT71 · Mar 25, 2003

that's a good idea but would cost a fortune for a laser that could hurt someone also...

bigben2k · Mar 26, 2003

As Since87 pointed out, the use of lasers is limited. In the kind of power range that we're talking about, I would have to assume that this is already a pulsed laser, which would have been the key to using it with Copper. A cooling solution would be required, but it would have to be liquid, and not interfere with the laser. I just don't see it happening.

BTW, the article linked is about resurfacing a steel beam, not cutting it.

As for casting copper, it is quite possible. It has even been suggested to use a steel mold! Not a DIY project.

Crash893 · Mar 27, 2003

im not talking about cutting it

im talking about resurfaceing it

lay the hs on its back

have a laser zap it for like a millionth of a second

it melts the top 1/100 of an inch of the copper and it cools flat

bafbrian · Mar 27, 2003

Sounds like a plausible idea, but like what is further up, who has a LASER you can borrow ?

Besides, will we never know till one of us tries it out.

I think it is genius, pure genius.

LOL

Crash893 · Mar 27, 2003

well if i get my hands on a high power laser i might get around to doing this allthough i can think of like 1000000 things ill shot it at first

Since87 · Mar 28, 2003

Crash893 said:
have a laser zap it for like a millionth of a second

it melts the top 1/100 of an inch of the copper and it cools flat

It might 'cool smooth', but what makes you think it would 'cool flat'?

TollPhree · Mar 28, 2003

hmm =P What about water cut.. =P serisly I saw they cut steel with water howz that work?

RadRacer · Mar 29, 2003

I'd like to know where you saw that. I don't think that would work at all. Are you sure they simply weren't cooling the steel with water?

GigaForce310 · Mar 29, 2003

You can cut steel with water. It takes very high pressure [thousands of PSI] going thorugh a tiny needle. It puts so much force on a concentrated area that it blasts a very fine section of steel out. The problem is that it only works with relitivly thin metal. Something along the lines of 1/2"-1/4" depending on the hardness of the steel.

This won't give a perfectly flat surface any more than lapping will. I think the best way to cool a processor is to take a heatsink or waterblock and make the processor right on it. Lapping a heatsink with 600+ grit sandpaper is just about as good as it gets.

donny_paycheck · Mar 30, 2003

Copper can be sprayed with an anti reflective coating to reduce its albedo and increase its fusion. An AR coat would make this MUCH easier, as copper is much more difficult to process using laser light without an AR coat. This would take care of your heat dissipation problem in the instant that would be necessary for surface refinishing.

Diggrr · Mar 30, 2003

It probably could be done, as the laser would heat it much faster than any metal could dissipate it.
But my question is, why? As I understand it from BillA's flatness tests, the cpu isn't that flat, so it would be a superfluous step.

One thing I'd like to see tried is silicon vapor deposited onto a 2" square heatsink (or waterblock, better still), and the circuitry etched onto that. Then add a substrate ring and contacts...violla! No more tiny hot die, and no more frail surfaces, or ineficient heatsinking interfaces.
This would also get rid of the need to make MONDO expensive silicon slabs. Could save a bundle of money (both theirs and ours).

Just my idea.

madcow235 · Mar 30, 2003

If it gets to hot just keep the thing submerged in LN2 and there will be no problem the laser will heat the metal it touches but nothing else will warm up. Now i must find a laser

could you use a laser to lap a heatsink?

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