Hey guys, here is a short "How-To" for heatsink lapping.
Materials needed:
1. A good flat piece of glass or mirror (maybe about 6" x 8").
2. Wet/Dry sandpaper of of several different grit-sizes
I generally start with #320 if the heatsink surface is uneven
or feels rough to the fingernail (machining marks). Then,
I'll go to #600 or so, and maybe finally to #900 or #1000.
If the heatsink is already fairly smooth, you may be able to
start with, say #400 grit and stop with #600.
Process:
1. You don't need a "mirror-like" finish - what you want is smooth
sheen and flat, with no scratches or machining marks left.
2. Soak a partial sheet of sandpaper in water, briefly then lay it
out grit-side up on the glass; keep it drenched all the time.
You may even want to rinse off metal particles under the
faucet occasionally, to keep a good grinding surface.
3. Gently rub the working surface of the heatsink on the paper
in a circular or figure-8 motion. You don't need to press hard;
keep the paper wet and let it do the work. Every 1-2 minutes
rotate the heat-sink by 90% trying to wear away the surface
evenly, so it comes out flat.
4. Check results after 5-10 minutes with the first grade of paper.
When you've gotten rid of all the machining marks, move to
the next finer grit-size and continue, until you're satisfied
with the results.
5. Just remember, you don't need to grind away "half the metal"
you just want a nice smooth, flat surface to mate to your CPU.
Depending on how good/bad your heatsink is to start with,
this process might take anywhere from 20 minutes to an hour.
6. When you are done, carefully clean all the grit and crud off the
heatsink with something like rubbing alchohol or acetone.
Clean the surface of your CPU core the same way.
Don't Touch the CPU or heatsink surface with your fingers -
no matter how clean you think they are you'll leave skin oils
on them and that will hurt your cooling results.
7. With a clean razor-blade or straight piece of stiff plastic,
spread a THIN layer of Arctic Silver-3 on the CPU core.
A small glob about the size of a grain of rice will be way 'nuff.
Then, mount the heatsink, being careful not to smear the
AS-3 around.
That all there is to it. When I first did this with an old AMD T-Bird
chip that was running darn near 60C, it got me about 8C cooler.
Have fun, and be cool!
but how do u lap a heatsink?
