lapping/polishing whats best

569 Views 12 Replies 7 Participants Last post by insulglass, Dec 20, 2006

MADMAX22

Discussion Starter · Dec 19, 2006

ok maybe you guys can clear this up for me a bit, i understand exactly what each is and all that stuff but what im interested in is somestuff that i read a couple dyas ago about lapping then polishing to such a fine smoothness that it actually stops helping and starts degrading the temp that youll get

i think one of the threads i saw that had a link to some experiments was on extreme systems but i cant find it again, this link detailed some stuff about how with a slightly rougher surface like 1200 grit instead 2000/2500 would give you better temps due something about the tiny little peaks would crush down a bit and with the thermal paste creat more of a surface area and promote better heat transfer

now i could be off on the grits i am thinking but you should get the idea, anyways any info from any searches you guys have done in the past would be much appreciated, thanks

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Syrillian

· #2 · Dec 19, 2006

Wow, so many lapping questions lately.

I think that 90% of the members are obssesive/compusive - I am.

If you do a nice lapping job on your surface(s) to anything from 1200 to 2500 grit you will see a dramatic drop in temps that will open up higher clock speed potentials, if you so choose. Or, it will drop your current high-temps to numbers that are far more comfortable.

I wouldn't agonise too much over it. I'm not trying to be an arse.... I went to 2500... But I don't think that it was necessary.

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Blowie

· #3 · Dec 20, 2006

rofl and i think you're right syr ! and i still have to test 12000 grit. i think it's an overkill but you never know.

i think the best performance out of lapping is: the biggest surface (meaning the biggest cm per surface..) damn my technical english is bad

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Syrillian

· #4 · Dec 20, 2006

Blowie, you are now knighted "OCN's lapping guinea pig"

I hope that you do it and that you post the best pics that you can take.

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ira-k

· #5 · Dec 20, 2006

If it's not concave I just hit it on 1000 grit on plate glass till I 'm sure it's flat and smooth....If it's concave I use 800 grit and valve grinding compound till flat the hit it on 1000 grit...I don't see the need to make it mirror like...

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insulglass

· #6 · Dec 20, 2006

Quote:

Originally Posted by ira-k

You should lap as fine as possible such that the largest grain size of thermal interface material in the matrix will overfill the scratches. That is, put another way... lap until the micronized silver particles in AS5 are too big for the grooves left by your snadpaper.

Which is no time soon. You can't lap too much, using a sound technique - generate flatness first and foremost and then the minimum RMS surface finish.

David

EDIT: Of course there is a law of diminishing returns the finer you go... but until you match the scratch grooves to the TIM particle size, you will not have reached the theoretical maximum benefit from lapping. My suggestion - lap through 2000 grit minimum and go beyond that as your budget, patience, and strength permit.

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ira-k

· #7 · Dec 20, 2006

Really? I think it's a waste of time....No harm I guess if you want to...But not really needed....

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insulglass

· #8 · Dec 20, 2006

Quote:

Originally Posted by ira-k

Really? I think it's a waste of time....No harm I guess if you want to...But not really needed....

I agree that it's a matter of preference. But if you're considering lapping to begin with, why not do it right and go all the way?

I guarantee you that the driver at the dragstrip wants every single horsepower out of his engine. Period. And if you have a need for lapping, going that extra step or two might be what it takes to get that extra 1C out of your cooler.

Once again, it takes time and effort to lap your sink and CPU. It's not for everyone.

David

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ira-k

· #9 · Dec 20, 2006

LOL...Yeah thats why I just started cutting off my IHS's....

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imaweirdo159

· #10 · Dec 20, 2006

Quote:

Originally Posted by ira-k

LOL...Yeah thats why I just started cutting off my IHS's....

Exactly!

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terraprime

· #11 · Dec 20, 2006

yea but wat do you do to fix the problem of the different between the IHS and the heatsink there is after you take it off...in other words how do you get that same type of contact back?

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ira-k

· #12 · Dec 20, 2006

Quote:

Originally Posted by terraprime

yea but wat do you do to fix the problem of the different between the IHS and the heatsink there is after you take it off...in other words how do you get that same type of contact back?

I use a water block so it doesn't matter...Guys with HSF just shave a little off the plastic holder till it fits flat on the die....

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insulglass

· #13 · Dec 20, 2006

Quote:

Originally Posted by ira-k

LOL...Yeah thats why I just started cutting off my IHS's....

That is a perfectly valid technique, although not for the faint of heart.

I tell people... lapping and messing with your CPU WILL help your temps, but it WILL also void your warranty. Some people would rather just lap the sink and save the warranty.

David

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