Lapping, When to say when?

[Szech]

At first I wasn't going to lap my new Celeron 566, but then I decided that it would be best, since I'm overclocking it. I've been to Scotter's website (good stuff, BTW ), and that's all good and dandy for a K5, but what about FC-PGA CPUs? How do I know when to quit? Also, after I switch to higher grit sandpaper, how long do I lap the CPU? Last question: How do I take off the clip on my Golden Orb? Or is there some way to lap it with the clip on? I was thinking about duct taping sandpaper to a wood block, and using that to sand down the 'orb. Would this work? Thanks in advance.

[LiLRiceBoi]

Never tryed lapping before, but I would not use a wood block. They are generally not that flat. Try to find a truly flat surface such as glass.

[ramjet]

Did the wood block sandpaper thing. Made it worse and got bawled out. Stick with glass and wax-on/wax-off until you can't see any light pass through between the chip and heatsink when they are presssed together..

[This message has been edited by ramjet (edited 06-13-2000).]

[Target]

Lapping the newer Celerons and PIII's is tricky business. The exposed core doesn't leave nearly as much margin for error as the previous CPU generations did.

Surprisingly, there is more silicon under that little blue patch than you think, but the problem is that you don't really know how thick it is, nor is there a good way to measure the depth to which you lap.

The real shame (risk) is that just under that silicon are the pins and other components that make up the CPU. If you go even slightly too far, you can pretty much write off the CPU as keychain material. On the older ones, when you saw copper of the cap, you knew you had taken the lapping about as far as you dared. On the new ones, when you see copper/metal, its too late.

Not trying to discourage you from lapping, but you really need to proceed with caution. If you are dead set on lapping it, I'd recommend doing so only slightly. Removal of the blue surface, and a little bit of the silicon, is probably about all you can safely do with minimal risk. Much more than that, and its anybody's guess. Have also seen pictures of lapped PIII's, and their silicon insulation on the core actually cracked. Not sure if they were that way to begin with (pre-lapping), or if the lapping process and pressure used caused the cracking.

If you decide to lap the CPU, LiLRiceBoi is right...... blocks of wood are terrible for use as a lapping surface. Glass or a mirror are much better. After switching to the higher grade of sandpaper, you really only need to lap until the surface is smooth and polished. In fact, given that you're not going to need to remove much from the surface of the CPU anyway (as they are surprisingly flat to begin with), I'd recommend that you start out with a fairly high number (fine grit) paper to begin with. It will take a little longer to do the lapping, but it will prevent you from going too deep by accident.

As for lapping the ORB, I think that removing the mounting clip is the only way to go. Trying to do so with it on will be difficult to say the least. I've never owned one, but my understanding is that they twist off from the mounting clip. Then you can remove the clip from the Zif socket, and get the CPU out cleanly.

*edit* I really should use that darn spell-checker <lol>

[This message has been edited by Target (edited 06-15-2000).]

[Szech]

Thanks everyone. Your council has made me decide NOT to lap it. If it makes 850, it makes it, if it doesn't, then 566 is more than 0. I'll figure out some other nifty way to cool it. Thanks again

[RobRich]

Target is dead on, as lapping a .18 micron cpu is really dangerous. The core has no real protection, besides a very thin layer of silicon. I will lap a p2 or k6 with no second thought, but a Coppermine or C-II I wouldn't even attempt it.

As for the ORB, they are usually very flat. If you do lap it, use an extremely fine grit sandpaper (800+), and take your time. Then re-apply a very thin layer of good thermal paste. This should more than adaquate for cooling a C-II. The .18 Intel core is very cool running as compared to older chips, and the ORB should prove more than satisfactory for convential cooling.

Robert Richmond

Edit: Looks like they already talked you out of it, which is probably a good thing. Wouldn't want to make a keychain out of that Celery, would ya'?!

[This message has been edited by RobRich (edited 06-14-2000).]

[Inferior]

Scotter has a site?

Can someone tell me the address please?

[Szech]

www.comppwizz.com