Originally Posted by VonDutch
IHS lapping ( 400 grit --> 800 grit --> 1000 grit). Read this composite pic from left-to-right and from top-to-bottom:
As evident in the photos, the IHS on this 3770K was quite concave, that is,
higher in the middle than elsewhere. "Flatness" was achieved in this case
when no more silver color remained on the IHS.
one uses wet/dry sandpaper and a flat surface (glass usually) to slowly and
iteratively grind an uneven surface. The goal of lapping is not be to make
a mirror surface, rather, it is to make flat surface.
waking up, g'morning
, and done some "info looting" while drinking my coffee
saw you guys talk about sanding ihs etc ..so ..i like pictures, easier then 1000 (grit) words right ..lol
i must say, most peeps say it didnt help much, i thought the same till now,
1-3C max difference, others saw no difference at all, so im surprised about the
extra 11C tempdrop..
First, here is the sequence of pics taken during the various stages of lapping.
To determine if the IHS was initially convex (crowned in the middle) or concave (like a bowl),
I used a sharpie permanent marker to make an X across the surface of the IHS:
Then I did just a few strokes on 220 grit before inspecting it,
knowing that the portions of the original "X" would only be removed from the high spots on the IHS:
very clear indication that the IHS is/was concave (like a bowl, the center was low and not touched by the sand paper yet,
the edges were high and have already been sanded down a bit, enough to begin to remove the permanent pen markings)
A bit more sanding with 220 grit yielded the following "copper ring" expected for a concave IHS:
We want all the nickel removed, nickel has a lower thermal transfer rate than copper, so I finished sanding off all the nickel with 220 grit:
check out how it looks after going all the way up to 3000 grit, love it
if anyone is going to do this lapping thing,
note before and after results if you can,
might be usefull for others, we have this saying,
"one day of Sun, doesnt make a summer"..
so, results that one may have, wont mean others will have the same,
its like with the usage of different tim's on die,
took a while and results from different peeps, to be sure liquid pro/ultra are the best to use on die right
o, about the "bowl" effect on that pic with the green markings,
dont forget if you put down the bracket on it, it will get less by the pressure...i thought..
well, to make sure noone will sue me, lol,
these are the original links,