Newb question: "lapping"?

[jinsean]

Hi, what is "lapping" the IHS mean?
IHS = internal heat sink??

I think I've read this in other contexts too (e.g. lapping the CPU)...

Thanks in advance.

[jimmyz]

ihs= integrated heat spreader. and lapping one means making the top surface as flat as possible by sanding or other means. most people use a peice of glass and some damp sand paper. lay the damp sandpaper on the glass so the abrasive is up and rub the processor over it to reveal the high spots then keep going until there isn't any high spots and all of the ihs is making contact.

[123bob]

It's important to note that lapping voids your warranty. It takes the label off the processor top. Most of us don't care, but be aware. There are plenty of threads to show exactly how to do it if you want to.

The reason to do it is for max heat transfer. The conroes are notorious for having all sorts of non-flat contact with your heatsink. Mine had quite a hill right in the middle. Since it is a quad, and hot anyway, that made cooling it near impossible for much of an overclock.
Bob

[RockfordFosgate]

my lapped e6400 :)

http://img524.imageshack.us/img524/1787/02042007692ph2.jpg

http://img524.imageshack.us/img524/8110/02042007693er1.jpg

http://img506.imageshack.us/img506/1171/02042007695tg4.jpg

[justin_c]

IHS: integrated heat spreader.
the more area, the better the heat disappation.
it consists of tin and copper, copper on top of tin. copper is the better conductor.
in order to have best thermal contact, both surfaces must be as smooth as possible. thermal compound fills in the tiny minuscule gaps between the heatsink and the IHS.
therefore we lap the ihs in order to make it as flat as possible.

[serialk11r]

so the IHS in only copper and tin, no electronics or the like?

Uh, yes...
Of course there aren't any electronics lmao, if there were, then why would people who took their IHS off have working CPUs?
The IHS is more there to protect the CPU. Its so thin it doesn't do much heat spreading, and its an additional layer of metal for heat to go through.
I think the gray stuff isn't tin but who knows. BTW if you want to lap, don't use polish or whatever.

[R B Customs]

my lapped e6400 :)

[img]http://img524.imageshack.us/img524/1787/02042007692ph2.jpg[/img

[img]http://img524.imageshack.us/img524/8110/02042007693er1.jpg[/img

[img]http://img506.imageshack.us/img506/1171/02042007695tg4.jpg[/img

wow, you actually used a rotary polisher and compound to polish your IHS... that must be VERY flat now.
GG

Lapped chips DO NOT need to be shiny. the whole point is to get them flat, not bling.

A sheet of glass, or special lapping surface ( most use glass), and varius sheets of fresh, good quality 'wet n dry' is all you need. you can go to whatever grade you want. but theres no point trying to make it shiny

Try not to use glass surfaces such as coff3ee tables etc, they may sag.

[ColonelCain]

jw, but i read somewhere that lapping intels was dangerous becasue it could ruin the CPU, but AMDs were fine. so i asked

Were'd you hear that?

You might have heard that removing the IHS from an Intel was dangerous (In previous batches, the IHS's were soldered to the processor) making removal impossible.. Now, Intel just uses paste. Same as AMD has.

[serialk11r]

Were'd you hear that?

You might have heard that removing the IHS from an Intel was dangerous (In previous batches, the IHS's were soldered to the processor) making removal impossible.. Now, Intel just uses paste. Same as AMD has.

Didn't some AMDs have soldered on IHSes as well?

[Tuppen^^]

Yes, some X2's have soldered IHSes.. I saw I guy trying to take of the IHS on a X2 6000+, and failed miserably.. xD

[jessethebody]

what about cleanup after a lapping of a cpu, especially with wet sand paper lapping? i mean getting water and dust under the ihs. any chance of that?

[justin_c]

you could tape the edges, where its "beveled" to the chip's substrate. therefore covering the gap with tape then lapping the top surface then removing it. clean it with alcohol, rub it super clean. you shouldn't need to clean it off with distilled afterwards.

[jessethebody]

i know its best to lap a heatsink with wet or soaped sandpaper for smoothness of operation, i assume lapping with dry paper would be quite rough.or is it best to lap a cpu dry?

[SNiiPE_DoGG]

fine grit sand paper is supposed to be wetted with water before use

[AllAgainstPaul]

oh i see. interesting. should all sand paper be wetted in this way?

No Only Sandpaper that says wet or wet and dry. I don't know for sure but I think basic sandpaper has a different paper type or grit adhesive that doesn't work to well when wet.

[CedricFP]

wow, you actually used a rotary polisher and compound to polish your IHS... that must be VERY flat now.
GG

Lapped chips DO NOT need to be shiny. the whole point is to get them flat, not bling.

A sheet of glass, or special lapping surface ( most use glass), and varius sheets of fresh, good quality 'wet n dry' is all you need. you can go to whatever grade you want. but theres no point trying to make it shiny

Try not to use glass surfaces such as coff3ee tables etc, they may sag.
I have a feeling that polishing the IHS actually decreases it's thermal performance, especially if there is a polishing substance used.

[serialk11r]

I have a feeling that polishing the IHS actually decreases it's thermal performance, especially if there is a polishing substance used.

It does...The polish doesn't exactly conduct heat well.

[p8ntslinger676]

gradually step up in grit, use say 180-300 for the initial sanding to get the ihs flat, then go to 600 then 1000 then 2000 for a nice smooth surface when i did this (went up to 4000grit) i saw a large temp drop since my ihs was concave so before i lapped it i got poor heat transfer in the middle.

[123bob]

Question. If one was to prep the lapped CPU surface with alcohol/acetone/as-cleaner, why would it matter if the surface was polished? I did some polishing on my quad, then followed that by several acetone cleanings to get the goop off. It seems to run fine. It would seem to me that smoother is better, no need for the paste to fill the gap. Just a question...:)

BTW, I always do my lapping dry. The reason for the water is to carry away the particles off the paper and allow more strokes on the given path. I use several sheets of paper, and when it appears fouled, I move on to another spot. I figure that gives the flattest lapping. For the question of what this paper is, it is silicon carbide, and it would seem the best stuff comes from Finland now days.

However, now that I think more about it, my Dad used to hone chisels and knives so sharp that they could be used for eye surgery. He used diamond flats, which I inherited. (He's long gone, and I'm no spring chicken either...:p: ) I'll have to give that a whirl...
Regards,
Bob

[jinsean]

wow, thanks for all the info guys... it all makes so much more sense now...