CPU lapping guide

Mr_T

Mr_T

Mr_T

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Joined
7 Feb 2006
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726
Location
Perth, Australia
A couple of people have been asking for a lapping guide and as I have just lapped my E6600 I thought I'd put a guide together on what I did.

Get the right sandpaper

Firstly I had to source some "wet & dry" sandpaper at the following grit grades...
400, 600, 800, 1000, 1200 (1 sheet of each) - You can go higher but I didn't

I managed to get the 400 & 600 sheets from B&Q but had to go to a car accessories shop to get the other grades as the higher grit grades are typically used for body work on cars.

The next step was to get a flat surface to mount the sandpaper on... I pulled apart an old photo frame and used the glass front.

I then placed the glass on my kitchen bench and the 400 grit on top of that. The paper was flat when i got it so i didn't have any issues with it not lying flat against the glass.

I ran the cold tap over the 400 to start with and then shook it about to get any excess water off the surface then placed in on the glass... (I only used water with the 400 & 600, and did it dry with the higher grades)

Now it was time to get the cpu!

I cleaned all the pase off the chip with good old tissue paper and a little cap of Smirnoff Import strength Vodka (50%) - It was all I had to hand!

I didn't cover my chip while I did the lapping, if I had kept the plastic holder that the chip came in I would have used that to protect the back but I threw it out.. ho hum it still worked!

step1.jpg

Say goodbye to the IHS labeling

Now as for lapping techniques I've read different things everywhere I looked.. But i did the following....

Placed the IHS on the 400 holding the cpu by the side and started moving it up & down the paper in a straight line making sure i put only a little pressure on the cpu. I repeated the motion for about 10 seconds then turned the chip 90 degress (clockwise or anti clockwise its up to you) and did the same motion for the same amount of time again. Untill the cpu had completed a revolution.

At the start i looked at the surface of the cpu after every revolution (out of interest to see where the copper was showing) The first place I noticed wear was the corners...

step2.jpg

The corners were the first to show any wear

After every 3 - 4 revolutions I moved the cpu onto a fresh part of the sand paper. I used the 400 grade untill I got about this far...

step4.jpg

Starting to see copper at the center of the cpu

In total I must have completed about 25-30 revolutions at each sheet before I then moved onto the higher grades. I also cleaned the cpu up after every change of sheet as you get a build up of fine grit on the pcb.

By the time I finished the 800 grit the cpu looked like this.

step5.jpg

Almost there!

Eventually after completeing the 1200 grit I decided it was time to clean the cpu one last time and wack it in!

step6.jpg

Cross your fingers!

I probably wasn't as professional as some people would be when doing this, but it worked and I knocked about 6-8 degrees off my idle temp.


Warranty
If it wasn't obvious... doing this to your cpu will void its warranty
 
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Nice guide! :)

How much AS5 (or whatever you used) did you use on the lapped CPU? Same as normal, or much less given that it's flat and surface to surface contact betwen it and HSF is now much closer?

I would say that the advice given by Arctic on application - i.e a thin line down the middle - takes into account the concave nature of the Conroe chips. Once lapped and flattened, the traditional spreading method with a credit card or razor blade may be the more effective method.

;)
 
Yeah I used AS5 & did the thin line down the cpu method as covered by arctic, but I had to take my heat sink off at one point and when I did that I used a credit card to smear the paste over the heat sink. Each to their own really.
 
Good guide.

In the past with A64 cpu's I put a rulers edge over the top pf the cpu to see how much it was flat and worked on the area's that needed work.

It always works out that the edges start to wear first, its the edges that are usually very slightly higher that the center which means to get better contact it would need lapping.

Seen other lapping jobs in the past where the IHS has been like a mirror. It doesnt matter if your IHS isn't like a mirror, just as long as its flat and gets better contact with the heatsink.

Was thinking of lapping the A64 Ive got coming but theres no point as the IHS has been popped off already. Something really that I would have like to se the C2D's be able to do.
 
I would suggest NOT to use brasso. It will only fill the microscopic grooves and pits, which is where the thermal compound should be. I would lap it down as flat as possible with wet and dry, then clean it thoroughly with Isopropyl. Then finally work a tiny bit of AS5 into it and rub it off. This should make sure that its as flat as possible, but also that any pits and grooves are filled with thermal compund rather than any other contaminant.
 
Top Guide! Makes you wonder why intel don't sell a "lapped" processor OEM tbh. Especially if you can get temps like that. Would save rubbing sandpaper against your chip which would make me squirm with each rub ^^

Alf
 
When I first put the cpu back on the board after the lap I couldn't get the machine to boot... took it out and reseated it a couple of times before it came back up... needles to say I was cacking myself!

I'm sticking to 3.24GHz at the moment as even though I can get 3.6 stable the load temps end up at about 64 degrees as opposed to 53degrees @ 3.24
 
I good tip is to polish it off with generic t-cut.

Your CPU still looks rather blemished but if it has had the desired effect then rock on.
 
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